the effect of a guided enquiry based learning …

THE EFFECT OF A GUIDED ENQUIRY BASED LEARNING APPROACH ON MECHANICAL ENGINEERING STUDENTS’

UNDERSTANDING OF THERMODYNAMICS

by

CHRISTOFFEL LOUW

A thesis submitted in fulfilment of the requirements for the degree of

DOCTOR OF EDUCATION (D.Ed) (In Technology Education)

at

WALTER SISULU UNIVERSITY

SUPERVISOR: PROFESSOR K. J. MAMMEN

MAY 2012

ii

ABSTRACT

Personal experiences of almost 17 years as an academic in engineering education in South Africa indicate that with the current teaching methods which are in use, course outcomes as required by the South African Qualification Authority (SAQA) are not achieved in learning Thermodynamics 2 (MTHE 2). The purpose of this research was to investigate alternative methods of teaching and learning MTHE 2 which would assist to improve the students’ academic performance. The population for this research was students registered for National Diploma Mechanical Engineering and the accessible population was 40 students registered for MTHE 2 from Walter Sisulu University, Chiselhurst campus. Out of these 40 students, 20 voluntarily agreed to be the sample. The theoretical framework for this study was social constructivism. Social constructivism states that learning is an active process and the process of knowledge construction occurs in a socio-cultural context where the student and environment actively interact. The student involves himself/herself and does neither remain nor be allowed to remain just as a passive observer. This was an action research where students were exposed to Guided Enquiry Based Learning (GEBL) in groups. From a social constructivists approach to learning, GEBL was used to engage students in social groups during the teaching-learning process with specific focus on selected academic discipline. All ethical considerations applicable to a study of the present nature were adhered to and in addition, signed informed consent forms were obtained from participants prior to the study. Students were given an introduction to the concepts and principles as per the pre-set syllabus for MTHE 2 and this was followed by problem solving sessions in which they were divided into four groups of five students each. The students were given a guided enquiry- and work-based example with an additional list of questions on each module of the syllabus. They had to select the most relevant questions from the list to analyse and develop a solution for each problem. The lecturers’ role was that of a facilitator who assisted each group with problems which the group encountered. This approach engaged students more actively in the learning process and placed more responsibility on them for their own progress in learning. This process also created an atmosphere for interaction with peers and assisted them to develop interpersonal and group communication skills. Key performance indicators were developed to measure the extent to which these outcomes were achieved. The researcher made use of an instrument structured in terms of Likert-type scale in order to objectively assess the extent of achievement. Data collected from the pilot study done in 2009 indicated that GEBL improved the students’ understanding of course content and problem analysis. Quantitative data were collected by means of standard assessment i.e. semester tests, an oral test, final examination and a KPI instrument. The KPIs were formulated to measure the extent to which the outcomes for MTHE 2 had been achieved. Qualitative data were collected through 30-minute interviews, using an open-ended interview schedule, with each member of the sample. The interviews were done by a person who qualified both as an ‘insider and outsider’ in order to minimize the risk of bias and to maintain rigour in the research. In order to qualify as an ‘insider and outsider’, one ought to be as an insider: (a) from the same ethnic group, (b) qualified in Mechanical

iii

Engineering with Thermodynamics as a major course, (c) had no power disposition e.g. a former student or a laboratory assistant (excluding staff members within the mechanical engineering department) and as an outsider, one who was not part of the GEBL process. The quantitative scores from the assessments were analysed with Predictive Analysis Software (PASW) to determine the extent to which interventions had assisted student performance. The qualitative data from the interviews were analysed with N-Vivo to reveal the impact of GEBL on student learning and understanding of MTHE 2. The results indicated that with GEBL, the students’ overall scores improved from the first assessment score of 46% written on half of the first module to the final assessment score of 55% written on all seven modules. Students could handle larger volumes of work and still obtain a higher percentage. GEBL assisted students’ in recalling factual MTHE 2 concepts, understanding of MTHE 2 concepts, principles and applications. GEBL also enhanced students’ ability to communicate procedures and processes related to MTHE 2. KPIs formulated to measure the extent to which the outcomes were met in terms of student achievement indicated a 57% achievement thereof. The KPIs developed gave a percentage achievement of the specified outcomes for MTHE 2 with GEBL. Theses KPIs can be used in future to measure the effectiveness of different teaching and learning methods in terms of achieving the outcomes. It is therefore recommended that GEBL be introduced into other engineering courses also to assist students in understanding course content and in achieving the course outcomes.

iv

DECLARATION

I, Christoffel Louw declare that the thesis entitled ‘The Effect of a Guided Enquiry Based

Learning Approach on Mechanical Engineering Students’ Understanding of

Thermodynamics’ is my own work. All sources and resources I have used or quoted

have been indicated and acknowledged by means of complete references.

___________________

(Christoffel Louw)

_________________________

PROFESSOR K. J. MAMMEN

SUPERVISOR

v

PLAGIARISM DECLARATION

1. I am aware that plagiarism is defined at Walter Sisulu University (WSU) as the

inclusion of another’s or others’ ideas, writings, works, discoveries and inventions

from any source in an assignment or research output without the due, correct

and appropriate acknowledgement to the author(s) or source(s) in breach of the

values, conventions, ethics and norms of the different professional, academic and

research disciplines and includes unacknowledged copying from intra- and

internet and peers/fellow students.

2. I have duly and appropriately acknowledged all references and conformed to

avoid plagiarism as defined by WSU.

3. I have made use of the citation and referencing style stipulated by my

lecturer/supervisor.

4. This submitted work is my own.

5. I did not and will not allow anyone to copy my work and present it as

his/hers own.

6. I am committed to uphold academic and professional integrity in the

academic/research activity.

7. I am aware of the consequences of engaging in plagiarism.

_______________ _____________ Signature Date

vi

ACKNOWLEDGEMENTS

I would like to take this opportunity to acknowledge and thank the following people

who helped me throughout my Doctoral Studies:

My supervisor, Prof K. J. Mammen, for his continuous support, for showing

confidence in my abilities, for his guidance, advice and encouragement throughout

this study,

The Management of Walter Sisulu University (WSU) for allowing me to conduct this

research,

The WSU Research Development office for the research grants,

The WSU Faculty of Education for general academic support,

The WSU Faculty of Engineering for allowing me to conduct the research within the

Mechanical Engineering Department,

All my colleagues for their encouragement, assistance and support throughout this

study,

Messrs D. Bessinger and S. Mqayi for conducting the interviews,

Mr I. Saunderson for his assistance with data analysis,

The Thermodynamics 2 students who participated in the research for showing

commitment, dedication and willingness to achieve success and for not withdrawing

from the study before it was completed,

Friends and colleagues for their moral support,

My wife and sons for their patience, understanding and support,

To everyone who helped me in one way or the other to complete this study.

vii

ACRONYMS

ABET : American Board for Engineering and Technology

BEST : Board of European Students of Technology

CBL : Case Based Learning

CHE : Council on Higher Education

EC2000 : Engineering Criteria 2000

ECSA : Engineering Council of South Africa

GEBL : Guided Enquiry Based Learning

EBL : Enquiry Based Learning

NDME : National Diploma Mechanical Engineering

PBL : Problem Based Learning

SAQA : South African Qualifications Authority

PASW : Predictive Analysis Software

MTHE 2 : Thermodynamics 2

UCL – Belgium : Universite Catholique de Louvain Belgium

WSU : Walter Sisulu University

viii

CONTENTS

ABSTRACT ................................................................................................................ ii

PLAGIARISM DECLARATION ...................................................................................... v

ACKNOWLEDGEMENTS ............................................................................................. vi

ACRONYMS............................................................................................................. vii

CONTENTS ............................................................................................................ viii

LIST OF TABLES .................................................................................................... xiv

LIST OF FIGURES ................................................................................................. xviii

CHAPTER 1 ............................................................................................................... 1

INTRODUCTION ....................................................................................................... 1

1.1 General Statement of the Problem .................................................................... 1

1.2 Background at WSU and global trends .............................................................. 3

1.2.1 NDME at WSU .............................................................................................. 3

1.2.1.1 NDME is listed as a Registered Qualification by SAQA ................................... 4

1.2.1.2 Accreditation by the Engineering Council of South Africa (ECSA) ................... 5

1.2.2 Weaknesses of the NDME at WSU .................................................................. 6

1.2.3 Teaching and Learning at WSU ...................................................................... 6

1.2.4 Global Responses to Traditional Engineering Teaching .................................... 7

1.2.5 Global Trends in Engineering Education ....................................................... 10

1.3 Aim ............................................................................................................... 13

1.4 Rationale and Problem Statement ................................................................... 13

1.5 Theoretical Framework ................................................................................... 15

1.6. Research Questions ....................................................................................... 19

ix

1.7 Objectives ..................................................................................................... 20

1.8 Significance of the Study ................................................................................ 20

1.9 Methodology.................................................................................................. 21

1.9.1 Research Subjects ...................................................................................... 21

1.9.2 Instrument and Data Collection ................................................................... 22

1.10 Limitations and Delimitations of the Study .................................................... 22

1.11 Definitions of Terms .................................................................................... 23

1.12 Organisation of the Thesis ........................................................................... 26

1.13 Summary ................................................................................................... 27

CHAPTER 2 ............................................................................................................. 29

LITERATURE REVIEW .............................................................................................. 29

2.1 Social Constructivism in Education .................................................................. 29

2.2 Active Learning .............................................................................................. 30

2.2.1 Enquiry Based Learning (EBL) and Guided Enquiry Based Learning (GEBL) .... 35

2.3 Inductive and Deductive Teaching and Learning and Learning Styles ................ 38

2.3.1 Inductive and Deductive Teaching and Learning ........................................... 38

2.3.2 A Spectrum of Learning Styles ..................................................................... 40

2.4 Effective Teaching ......................................................................................... 41

2.5 Significant Learning ....................................................................................... 43

2.6 Deep and Surface Learning ............................................................................ 45

2.6.1 Deep Learning ............................................................................................ 45

2.6.2 Surface Learning ......................................................................................... 47

2.7 Kolb’s Learning Cycle ..................................................................................... 48

2.8 Bloom’s Taxonomy (Cognitive Domain) ........................................................... 52

x

2.9 Outcomes and Key Performance Indicators ..................................................... 53

2.9.1 Outcomes ................................................................................................... 53

2.9.1.1 ECSA’s View on Outcomes ........................................................................ 54

2.9.1.2 SAQA’s View on Outcomes ....................................................................... 55

2.9.1.3 Exit Level Outcomes of National Diploma Mechanical Engineering at WSU ... 58

2.9.2 Key Performance Indicators ......................................................................... 58

2.10 Summary ................................................................................................... 61

CHAPTER 3 ............................................................................................................. 64

METHODOLOGY ...................................................................................................... 64

3.1 Action Research ............................................................................................. 64

3.1.1 Participatory Action Research ...................................................................... 65

3.2 Modes of Enquiry ........................................................................................... 67

3.2.1 Qualitative mode of enquiry ........................................................................ 67

3.2.2 Quantitative mode of enquiry ...................................................................... 68

3.3 Population and Sample ................................................................................... 69

3.3.1 Population .................................................................................................. 69

3.3.2 Sample....................................................................................................... 69

3.4 Ethical Considerations .................................................................................... 69

3.5 Instrumentation ............................................................................................. 70

3.5.1 Instrument Construction.............................................................................. 70

3.5.1.1 Formative Assessments ............................................................................ 71

3.5.1.2 Oral Assessment ...................................................................................... 72

3.5.1.3 Summative Assessment ............................................................................ 73

3.5.1.4 Structured Questionnaire.......................................................................... 73

xi

3.5.1.5 Key Performance Indicators ...................................................................... 73

3.5.1.6 Open-ended Interviews ............................................................................ 74

3.6 Pilot Study ..................................................................................................... 74

3.7 Instrument Reliability and Validity ................................................................... 75

3.7.1 Reliability ................................................................................................... 75

3.7.2 Trustworthiness (Qualitative Rigour) ............................................................ 75

3.7.3 Validity ....................................................................................................... 77

3.7.4 Triangulation .............................................................................................. 78

3.8 Insider Outsider Position to Interviews ............................................................ 79

3.9 Intervention Process ...................................................................................... 81

3.10 KPIs for this Study ...................................................................................... 85

3.11 Procedures ................................................................................................. 87

3.12 Data Analysis and Interpretation .................................................................. 88

3.13 Summary ................................................................................................... 89

CHAPTER 4 ............................................................................................................. 90

DATA ANALYSIS AND INTERPRETATION .................................................................. 90

4.1 Demographics of the Study ............................................................................ 90

4.2 Qualitative Data Analysis, Interpretation and Discussion ................................... 91

4.2.1 Addressing the First and Second Research Question ..................................... 92

4.2.2 Addressing the Third Research Question .................................................... 111

4.2.3 Summary of Qualitative Data ..................................................................... 119

4.3 Quantitative Data Analysis, Interpretation and Discussion .............................. 119

4.3.1 Addressing the First and Second Research Question ................................... 120

4.3.2 Addressing the Third Research Question .................................................... 165

xii

4.3.3 Structured Questionnaire ........................................................................... 178

4.3.4 Summary of Quantitative Data from Formative and Summative Assessments 196

4.3.5 Addressing the Fourth Research Question .................................................. 198

4.3.6 Summary of Data from KPIs for Tests 1, 1b, 2, 3, and Final Examination ..... 229

4.3.7 Summary of Data from KPIs for Oral Tests 1 and 2 ..................................... 240

4.4 Summary of Highest Scored Data ................................................................. 241

4.4.1 Theory Questions from Written Assessments .............................................. 241

4.4.2 Structured Questionnaire (see Appendix 1)................................................. 242

4.4.3 Interviews (see Appendices 2 & 13): .......................................................... 242

4.4.4 Oral Test 1 (see Appendix 7) ..................................................................... 243


4.4.6 Calculation Questions from Written Assessments ........................................ 245

4.4.7 Structured Questionnaire (see Appendix 1)................................................. 246


4.5 Summary .................................................................................................... 248

CHAPTER 5 ........................................................................................................... 250

DISCUSSION OF FINDINGS, CONCLUSION AND RECOMMENDATIONS ..................... 250

5.1 GEBLs Impact on Student Performance ......................................................... 251

5.1.1 High Scores - Written Theory Assessments ................................................. 251

5.1.2 High Scores - Written Calculation Assessments ........................................... 253

5.1.2.1 Factual Knowledge ................................................................................. 255

5.1.2.2 Conceptual Knowledge ........................................................................... 256

5.1.3 High Scores - Oral Assessments ................................................................. 257

5.2 KPI Achievement with GEBL ......................................................................... 258

xiii

5.3 Conclusion ................................................................................................... 260

5.4 Recommendations ....................................................................................... 262

5.5 Proposed Louw’s Model for Thermodynamics 2 .............................................. 264

5.6 General Model ............................................................................................. 265

5.7 Proposed Louw’s General Model for Engineering Courses ............................... 267

ACKNOWLEDGEMENTS .......................................................................................... 268

REFERENCES ........................................................................................................ 269

APPENDICES......................................................................................................... 285

Appendix 1 – Structured Questionnaire testing students experience with GEBL ......... 285

Appendix 2 – Qualitative interviews with students participating in GEBL ................... 286

Appendix 3 – Formative assessment 1 (semester test 1) ......................................... 292

Appendix 4 – Formative assessment 1b (semester test 1b) ...................................... 296



Appendix 7 – Formative assessment (oral test) ....................................................... 312

Appendix 8 – Summative assessment (final examination) ........................................ 318

Appendix 9 – KPIs for measuring achievement in outcomes with formative assessments

1, 2 and 3 ............................................................................................................ 325

Appendix 10 – KPIs for measuring achievement of outcomes of oral test 1 ............... 330

Appendix 11 – KPIs for measuring achievement of outcomes of final examination ..... 333

Appendix 12 – Louw’s Guided Enquiry Based Learning Guide for assisting students’

learning ................................................................................................................ 337

Appendix 13 – Student responses to interviews ...................................................... 440

Appendix 14 – Electronic Thesis & Dissertations (ETD) and Plagiarism Requirements 445

xiv

LIST OF TABLES

Table 2.1: Features of Common Inductive Instructional Methods (Prince & Felder,

2006, p.125) ........................................................................................................... 34

Table 2.2: Kolb’s Learning Cycle and Engineering Education Activities ...................... 50

Table 2.3: Movement through Kolb’s Learning Cycle with Teaching and Learning

Activities................................................................................................................. 51

Table 4.1: Demographic data ................................................................................ 90

Table 4.2: Quantitative Statistics on the Students’ Overall Performance in Written

Assessments ......................................................................................................... 121

Table 4.3: Quantitative Statistics on Theory Questions in Test 1 ............................ 122

Table 4.4: Quantitative Statistics from Analytical Questions in Test 1 ..................... 125

Table 4.5: Quantitative Statistics on Overall Performance in Test 1 ........................ 128

Table 4.6: Quantitative Statistics on Theory Questions in Test 1b .......................... 130

Table 4.7: Quantitative Statistics on Analytical Questions in Test 1b ...................... 133

Table 4.8: Quantitative Statistics on Overall Performance in Test 1b ...................... 136

Table 4.9: Quantitative Statistics on Theory Questions in Test 2 ............................ 139

Table 4.10: Quantitative Statistics on Analytical Questions in Test 2 ........................ 142

Table 4.11: Quantitative Statistics on Overall Performance in Test 2 ....................... 145

Table 4.12: Quantitative Statistics on Theory Questions in Test 3 ........................... 148

Table 4.13: Quantitative Statistics on Analytical Questions in Test 3 ........................ 151

Table 4.14: Quantitative Statistics on Overall Performance in Test 3 ....................... 154

Table 4.15: Quantitative Statistics from Theory Question in Final Examination ......... 156

xv

Table 4.16: Quantitative Statistics from Analytical Question in Final Examination ..... 160

Table 4.17: Quantitative Statistics from Overall Performance in Final Examination ... 163

Table 4.18: Quantitative Statistics on Reliability for Tests 1, 1b, 2, 3 and Final

Examination .... ..................................................................................................... 165

Table 4.19: Quantitative Statistics from Oral Test 1 ................................................ 166

Table 4.20: Quantitative Statistics from Oral Test 2 ................................................ 171

Table 4.21: Quantitative Statistics from Overall Performance in Oral Tests 1 and 2 .. 176

Table 4.22: Quantitative Statistics from Question 1 in Structured Questionnaire ....... 178









Table 4.31: Quantitative Statistics from KPI Analysis Measurements in Test 1 .......... 199

Table 4.32: Quantitative Statistics from KPI Analytical Measurements in Test 1 ....... 201

Table 4.33: Quantitative Statistics from KPI Performance Measurements in Test 1 ... 203

Table 4.34: Quantitative Statistics from KPI Analysis Measurements in Test 1b ........ 205

Table 4.35: Quantitative Statistics from KPI Analytical Measurements in Test 1b ...... 207

Table 4.36: Quantitative Statistics from KPI Overall Performance Measurements in Test

xvi

1b...... ................................... .............................................................................. 209

Table 4.37: Quantitative Statistics from KPI Analysis Measurement in Test 2 ........... 211



2.......................................................................................................................... 215

Table 4.40: Quantitative Statistics from KPI Analysis Measurements in Test 3 .......... 217



3................. ......................................................................................................... 221

Table 4.43: Quantitative Statistics from KPI Analysis Measurements in the Final

Examination .......................... ............................................................................... 223

Table 4.44: Quantitative Statistics from KPI Analytical Measurements in the Final

Examination ................................. ........................................................................ 225

Table 4.45: Quantitative Statistics from KPI Overall Performance Measurements in the

Final Examination .................................................................................................. 227

Table 4.46: Summary of results from KPI Measurements of Tests 1, 1b, 2, 3 and Final

Examination ........................................ ................................................................. 229

Table 4.47: Quantitative Statistics from KPI Explanation Measurements in Oral Tests 1

and 2………………………… ........................................................................................ 231

Table 4.48: Quantitative Statistics from KPI Understanding Measurements in Oral Tests

1 and 2........ ........................................................................................................ 233

Table 4.49: Quantitative Statistics from KPI Discussion Measurements in Oral Tests 1

xvii

and 2............ ....................................................................................................... 235

Table 4.50: Quantitative Statistics from KPI Overall Performance Measurements in Oral

Tests 1 and 2........................................................................................................ 237

Table 4.51: Summary of results from KPI Measurements in Oral Tests 1 and 2 ........ 239

Table 4.52: Quantitative Statistics for reliability from KPI Measurements in Oral Tests 1

and 2………………. .................................................................................................. 239

xviii

LIST OF FIGURES

Figure 1.1: Modified Zone of Proximal Development (R.G. Tharp & R. Gallimore's, 1988,

p.35)…………… ........................................................................................................ 16

Figure 2.1: Movement through Kolb’s Learning Cycle which can be enhanced by Active

Learning……… ......................................................................................................... 49

Figure 3.1: GEBL intervention flow process .............................................................. 83

Figure 4.1: Theory Question 1.3 in Test 1 reflecting a low level of Conceptual

Knowledge….. ....................................................................................................... 123

Figure 4.2: Theory Question 2.1 in Test 1 reflecting a high level of Conceptual

Knowledge….. ....................................................................................................... 124

Figure 4.3: Analytical Question 1.2 in Test 1 reflecting a low level of Factual and

Conceptual Knowledge .......................................................................................... 126

Figure 4.4: Analytical Question 1.3 in Test 1 reflecting a high level of Factual

Knowledge…… ...................................................................................................... 127

Figure 4.5: Overall Performance in Test 1 with a combined Factual and Conceptual

Knowledge achievement of 46.2% ......................................................................... 129

Figure 4.6: Theory Question 1.2 in Test 1b reflecting a high level of Conceptual

Knowledge….. ....................................................................................................... 131

xix

Figure 4.7: Theory Question 1.4 in Test 1b reflecting a low level of Conceptual

Knowledge…… ...................................................................................................... 132

Figure 4.8: Analytical Question 1.3 in Test 1b reflecting a high level of Factual and


Figure 4.9: Analytical Question 1.4 in Test 1b reflecting a low level of Factual and


Figure 4.10: Overall Performance in Test 1 with a combined Factual and Conceptual

Knowledge achievement of 46.2% ......................................................................... 137

Figure 4.11: Theory Question in Test 2 reflecting a low level of Conceptual

Knowledge……. ..................................................................................................... 140


Knowledge…….. .................................................................................................... 141

Figure 4.13: Analytical Question in Test 2 reflecting a low level of Factual and



Knowledge……. ..................................................................................................... 144

Figure 4.15: Overall Performance in Test 2 reflecting a combined Factual and

Conceptual Knowledge of 42.2% ........................................................................... 146


Knowledge….. ....................................................................................................... 149

xx

Figure 4.17: Theory Question 4.5 in Test 3 reflecting a low level of Conceptual

Knowledge…… ...................................................................................................... 150

Figure 4.18: Analytical Question 1.4 in Test 3 reflecting a low level of Factual and



Knowledge……. ..................................................................................................... 153

Figure 4.20: Overall Performance in Test 3 reflecting a combined Factual and

Conceptual Knowledge 43.74%.............................................................................. 155

Figure 4.21: Theory Question 7 in the Final Examination reflecting a high level of


Figure 4.22: Theory Question 9 from the Final Examination reflecting a low level of


Figure 4.23: Analytical Question 4 in the Final Examination reflecting a low level of

Factual and Conceptual Knowledge ........................................................................ 161

Figure 4.24: Analytical Question 5 in the Final Examination reflecting a high level of

Factual and Conceptual Knowledge ........................................................................ 162

Figure 4.25: Overall Performance in the Final Examination reflecting a combined

Factual and Conceptual Knowledge achievement of 51.16% .................................... 164

Figure 4.26: Question 7 in Oral Test 1 reflecting a high level of Conceptual

Knowledge…… ...................................................................................................... 167

xxi


Knowledge……. ..................................................................................................... 168

Figure 4.28: Question 34 in Oral Test 1 reflecting a low level of Conceptual

Knowledge…… ...................................................................................................... 169


Knowledge……… ................................................................................................... 172


Knowledge……. ..................................................................................................... 173


Knowledge………. .................................................................................................. 174


Knowledge………. .................................................................................................. 175

Figure 4.33: Overall Performance in Oral Tests 1 and 2 reflecting a Conceptual

Knowledge level 58.47% ....................................................................................... 177

Figure 4.34: Question 1 from the Structured Questionnaire reflecting 67% of students

‘strongly agree’ ..................................................................................................... 179


‘strongly agree’ ..................................................................................................... 181


‘strongly agree’ and 27% ‘agree’ ............................................................................ 183

xxii

Figure 4.37: Question 4 from the Structured Questionnaire reflecting 67% of the

students ‘strongly agree’ ....................................................................................... 185


students ‘strongly agree’ and 67% ‘agree’ .............................................................. 187


students ‘strongly agree’ ....................................................................................... 189


students ‘strongly agree and 60% ‘agree’ ............................................................... 191





Figure 4.43: Students Analytical Performance with an increased workload and with

GEBL introduced after Second Assessment ............................................................. 197

Figure 4.45: Students Analysis Performance with an increased workload and with GEBL

introduced after Second Assessment ...................................................................... 198

Figure 4.46: Analysis Measurements with KPIs in Test 1 ......................................... 200

Figure 4.47: Analytical Measurements with KPIs in Test 1 ...................................... 202

Figure 4.48: Overall Performance Measurements with KPIs in Test 1 ....................... 204

Figure 4.49: Analysis Measurements with KPIs in Test 1b ....................................... 206

xxiii

Figure 4.50: Analytical Measurements with KPIs in Test 1b ..................................... 208

Figure 4.51: Overall Performance Measurements with KPIs in Test 1b ..................... 210







Figure 4.58: Analysis Measurements with KPIs in the Final Examination .................. 224

Figure 4.59: Analytical Measurements with KPIs in the Final Examination ................ 226

Figure 4.60: Overall Performance Measurements with KPIs in the Final Examination.228

Figure 4.61: Overall KPI Achievement with an increased workload, with GEBL being

introduced after the Second Assessment ................................................................ 230

Figure 4.62: Explanation Measurements with KPIs in Oral Tests 1 and 2 ................. 232

Figure 4.63: Understanding Measurements with KPIs in Oral Tests 1 and 2 ............. 234

Figure 4.64: Discussion Measurements with KPIs in Oral Tests 1 and 2 ................... 236

Figure 4.65: Overall Performance Measurements with KPIs in Oral Tests 1 and 2 ..... 238

1

CHAPTER 1

INTRODUCTION

This chapter gives a background to this study and explains the current situation of

mechanical engineering education at Walter Sisulu University (WSU).

1.1 General Statement of the Problem

Personal experiences of almost 17 years as an academic in engineering education in

South Africa (SA) indicates that with the current teaching methods, course outcomes as

required by the South African Qualification Authority (SAQA) are not achieved in

learning Thermodynamics 2 (MTHE 2). Reports from various employers indicated that

students lack important skills required in the engineering field. The purpose of this

research was to investigate alternative methods of teaching and learning MTHE 2 which

might assist learning and improve academic performance.

The challenges contributing to engineering students’ poor performance are not unique

to SA. For example, the observations depicting experiences from India, the United

States of America and Ireland vividly indicate the challenges which engineering

education faces globally. The Indian Express newspaper reported that a large number

of engineering students from all 60 colleges across one of the states in India have failed

their examinations as declared on 27th February 2009 (Indian express.com, 2009, p.1).

2

This newspaper further reported that “250 candidates of a college who appeared for the

semester examination, 209 have failed in a paper” (Indian express.com, 2009, p.1).

Worldwide, institutions are investigating alternative methods of teaching engineering

students in order to improve their performance. According to Nicklow, Kowalchuk,

Gupta, Tezcan and Mathias (2009, p.1), an innovative programme was developed to “...

improve the overall graduation rate of engineering students from 37% to 67% over a

five-year period at the College of Engineering, Southern Illinois University, Carbondale,

(SIUC)”. Tully and Clarke (2008, p.3) state that “... graduation rates are often less than

40%” in the Dublin Institute of Technology (DIT) in Ireland.

The University of Massachusetts, Dartmouth, developed a completely new first year

programme to improve first year engineering education (Pendergrass, Kowalczyk,

Dowd, Laoulache, Nelles, Golen & Fowler, 1999, p.13c2-9). A research conducted on

Active Learning in Transportation Engineering and submitted to the Worcester

Polytechnic Institute indicated that active learning did have a positive impact on student

performance as measured by exam scores (Weir, 2004, p.2).

In SA the situation is not dissimilar and research has continuously been done to address

the challenges. In the Council on Higher Education’s (CHE, 2007, pp.25-26) annual

report it was stated that only 32% of first time entering students at ‘Traditional

Universities’ complete their engineering B-degree in four years and only 5% of first time

entering students at ‘Comprehensive Universities’ complete their engineering Diploma in

3

three years. Many of the engineering students are therefore not performing expected

and various factors might be contributing to this such as students’ attitudes towards

their studies and their background knowledge in the particular course as well as clashes

between lecturers’ teaching styles and students’ learning styles. This study investigated

teaching and learning factors and possible alternative innovations to address some of

the challenges.

1.2 Background at WSU and global trends

This section gives an overview of the National Diploma Mechanical Engineering (NDME)

at WSU in terms of its structure, accreditation, weaknesses, method of offering as well

as global responses to traditional teaching in engineering and global trends in

engineering education.

1.2.1 NDME at WSU

This study was carried out at WSU which is a public university in the Eastern Cape of

SA. The NDME offered at WSU is a three year full-time programme. Level one of the

diploma consists of two semester programmes (S1 and S2) each consisting of six

courses. Level two of the diploma is a semester programme (S3) consisting of six

courses and a six months Mechanical Engineering Practice 1 (MEEP 1). The final year of

the diploma is a semester programme (S4) consisting of six course and a six month

Mechanical Engineering Practice 2 (MEEP 2). The total number of courses required for

4

the theory part of the diploma is 24. Each course has a credit value of 0.083. Each of

MEEP 1 and MEEP 2 carry a credit value of 0.5 which gives a total credit of ‘3’ for the

diploma (WSU Faculty Prospectus, 2010, pp.119-120).

1.2.1.1 NDME is listed as a Registered Qualification by SAQA

NDME offered by WSU is listed by SAQA as a registered qualification. According to

SAQA (2009, p.1):

SAQA must develop and implement policy and criteria, after consultation

with the Quality Councils (QCs) for the development, registration and

publication of qualifications and part-qualifications, which must include the

following requirements:

- The relevant sub-framework must be identified on any document

relating to the registration and publication of a qualification or part-

qualification;

- Each sub-framework must have a distinct nomenclature for its

qualification types which is appropriate to the relevant sub-framework

and consistent with international practice.

SAQA must register a qualification or part-qualification recommended by a

QC if it meets the relevant criteria;

SAQA must develop policy and criteria, after consultation with the QCs, for

assessment, recognition of prior learning and credit accumulation and

5

transfer.

1.2.1.2 Accreditation by the Engineering Council of South Africa (ECSA)

The Engineering Council of South Africa (ECSA) is a professional statutory body that

visits tertiary institutions on a four year cycle to inspect the credibility of the

engineering programmes. The NDME at WSU is fully accredited by ECSA.

Recognition of National Diploma Programmes Accredited by ECSA via Dublin Accord

(2010, p.1) states:

This type of programme is a three-year programme, including two years of

academic study and one year of experiential training.

Engineering programmes listed in document E-20-PN have been accredited by

ECSA and are recognised as meeting the initial academic requirements for

registration as a Professional Engineering Technologist in South Africa.

Signatories are advised that accreditation of National Diploma programmes by

ECSA is subject to an appropriate choice of subjects by the student in each case.

On the E-20-PN document ND Accreditation List, Revision 1.1, 1 June 2010, p.6 of ECSA

(2009), the NDME at WSU is listed as accredited from 1996 when the first visit took

6

place. During every visit thereafter the NDME at WSU received full accreditation. The

next visit will take place in 2014.

1.2.2 Weaknesses of the NDME at WSU

Students’ pass rates in NDME at WSU in general are very low as revealed by the data

captured by Higher Education Management Information System (HEMIS, 2009).

According to the Integrated Tertiary Software (ITS) records, WSU, 2000-2009 the

average pass rate in MTHE 2 over the past 17 years is below 40%. Recorded pass rates

from 2006-2009 are as follow: semester two 2006-16%, 2007-20% and 2009-9%.

Records of feedback from various employers over the years also indicated that

graduates from WSU lack certain skills such as communication and group work crucial

for an engineering career.

1.2.3 Teaching and Learning at WSU

The fact that most of the mechanical engineering lecturers are more of professional

engineers than educators/academics and have not been exposed to or formally trained

in educational practices results in teaching and learning methods which do not cater for

a diverse group of students (WSU Faculty Prospectus, 2010, pp.14-18). Traditional

lecturing involves the lecturer presenting the course to the students verbally and the

students listen and take notes. Traditional lecturing is still considered as the most

effective method of sharing factual information with large groups. This method gives

7

the students guidance on what to concentrate on and can be sometimes inspirational

also. The student however needs to have good listening, reading, writing and speaking

skills to ensure that the learning process is effective (Holford & Moore, 1994, p.1). Good

note-taking skills are also crucial. According to Bales (1996, p.1) students remember

only five percent of what they have been taught during a traditional lecture.

Employers expect engineering graduates and diplomates to deliver immediately in terms

of high level of technical comprehension and application, technical communication and

presentation and professional behaviour. Employers mainly offer only specialised-skills

courses (e.g. a software simulation programme for a specific application) to them. As

such, the new graduates need to be prepared to deal with these expectations. For the

students, the only back-up is knowledge and the skills acquired at the university.

1.2.4 Global Responses to Traditional Engineering Teaching

Universities should not only teach students to “memorise knowledge”, but also focus on

developing their complex thinking and reasoning skills (Fink, 2003, p.2). According to

Kabir, Khan and Mahmud (2008, p.15), “... to successfully deal with the challenges of

the 21st century, engineers must possess three tools: knowledge, skills and attitude”.

Traditional teaching and learning approaches do not address these three tools with the

result that they are not developed by the time a student graduates. In September 2000,

Universite Catholique de Louvain Belgium (UCL-Belgium) introduced a new approach

which was more active and student-centred into their engineering curriculum, which

8

modified the traditional lecturer-centred teaching. This decision was inspired by, among

others, the high drop-out rates, low student motivation and shallow mastery of course

material, low retention rate, little demonstration of higher-order skills, not enough

initiative and autonomy (Aquirre, Jacmot, Milgrom, Raucent, Soucisse & Vander Borght,

2001, p.29). With reference to the traditional teaching and learning approaches Alters

and Nelson (2002, p.1893) state that “Problems with such instruction become evident

when student retention and understanding of even the most fundamental concepts in

the course is shockingly limited, as reflected in the low levels of scientific literacy even

among college graduates...”

Chang, Stern, Sondergaard and Hadgraft (2009, p.2) state that “Internationally, as

engineering schools grapple with how best to prepare effective engineers in the twenty-

first century, we are seeing a move away from transmission models of learning and

teaching, towards more constructivist models”. Chang et al. (2009, p.2) also explain

that “... the social dimensions of learning suggest that formal class time with academic

staff is not the only opportunity for engineering students to learn”. With regard to the

new challenges which the tertiary education faces in the 21st century, Salmi (2001,

p.106) states that “There are three major, intertwined new challenges which bear

heavily on the role and functions of higher education: (i) economic globalization; (ii) the

increasing importance of knowledge as a driver of growth, and (iii) the information and

communication revolution”. Quality control in higher education in Africa aims to address

a new range of competences also which graduates must acquire. These are

9

adaptability, team work, communication skills and lifelong learning. Countries which

want to address these competences must be willing to make changes in their content

and pedagogy (Materu, 2007, p.7). In SA, the traditional method of learning and

teaching the chemical engineering degree at University of Cape Town was changed and

it was accredited as an outcomes-based degree by the Engineering Council of South

Africa (ECSA) in 2001. Report from the research done by Martin, Maytham, Case and

Fraser (2005, p.179) on the preparedness of graduates following this outcomes-based

degree state that:

The study confirms the importance of technical skills as a basis of engineering

practice, as well as the need for communication, team-work and interpersonal

skills in the workplace. It also points to the complex interactions between these

different skills, specifically that the non-technical skills area built on a technical

basis, and therefore that a lack of confidence in the technical arena would

hamper abilities in these other areas.

As shown above, researchers indicate that more universities are considering active

learning methods in their quest to find a solution to the crisis. From those who have

introduced these new methods, favourable results have been experienced (Prince,

2004; Junglas, 2006). This study which was carried out at WSU would add value to

other national and international institutions.

10

1.2.5 Global Trends in Engineering Education

In the outcomes of the 1998 Global Congress on Engineering Education at Cracow

(Poland), it was stated that “... the integration of lectures with laboratory experiences

and project work was identified as an ideal scenario” (Jones, 1998, p.1). This author

further states that the “... one basic set of skills that must be developed in engineering

students is critical thinking and problem solving” (Jones, 1998, p.2). The Ministry of

Education in New-Zealand, called for a research culture that will have a research-based

approach (Spronken-Smith, Angelo, Matthews, O’Steen & Robertson, 2007, p.1).

“Critical instructional objectives for the 21st century engineering students include

problem-solving, design, communication, teamwork, self-assessment, ethics, lifelong

learning” (Criteria for Accrediting Engineering Programmes 2006-2007 cited in Huet,

Mourtos, Costa, Pacheco & Tavares, 2007, p.2).

With regard to the effectiveness of traditional teaching methods versus alternative

teaching techniques, Rugarcia, Felder, Woods and Stice (2000, p.10) state:

In the traditional approach to teaching, the professor lectures and assigns

readings and well-defined convergent single-discipline problems, and the

students listen, take notes, and solve problems individually. Alternative

pedagogical techniques have repeatedly been shown to be more effective and

much more likely to achieve the objectives.

11

Gibson (2002, p.470) states that there is “... a steady movement away from traditional,

formal teaching and examination methods across Western Europe towards a more

informal, PBL environment, which demands a variety of appropriate assessment

mechanisms”. Universities in America changed their Engineering Education approach to

fall in line with the Engineering Criteria 2000 (EC2000) approved by the Accreditation

Board for Engineering and Technology (ABET) in 1996. This required engineering

programme evaluation to move its emphasis from curricular specifications to student

learning outcomes and accountability. Course offering was changed to less lecturing

and textbook problem solving to more active learning approaches, for example, group

work, design projects, case studies, and application exercises. Lattuca, Terenzini,

Volkwein and Peterson (2006, pp.5-13) further emphasise:

The most frequent and influential programmatic changes were an increase in

emphasis on foundational knowledge and project skills in program curricula, less

reliance on traditional pedagogies, an increase in active and collaborative

pedagogies, and an increase in programmatic emphasis on assessment for

improvement.

ABET has changed the accreditation criteria and has placed more emphasis on the

project-based learning approach and also self-directed learning which will enhance life-

long learning. For students to be successful engineers in the 21st century they must be

well equipped. The ability to solve problems from a system-level perspective, to

12

communicate effectively, to be technically versatile, to be able to function in an ethnic

diverse team and to demonstrate social responsibility are some of the important skills

these engineers must poses (Savage, Chen & Vanasupa, 2007, p.2). These authors

further state that:

... undergraduate engineering educational curricula are facing a number of

challenges including a rapid growth in what is perceived by the technical

community to be a necessary foundation of knowledge, the realization that our

workforce must be able to operate in a diverse global society and the recognition

that the implementation of technology can have an enormous impact on the

sustainability of our global resources (Savage et al., 2007, p.2).

At the Durban University of Technology in SA, a study was conducted on an alternative

presentation of a chemical engineering design module. In this regard Ramsuroop (2011,

p.174) states that “... the chemical engineering design module in the national diploma

has focused on developmental projects associated with sustainability, which emphasise

hands-on learning”. This author explains that:

The primary objective was to adopt active learning methods that would: improve

students‘ physical interpretation and understanding of real engineering systems,

expose students to the notion that chemical engineering can provide solutions to

many of the challenges facing our society, develop the engineering hand skills

13

(especially since very few students engage in any DIY activities), improve

motivational levels in students, provide a platform for students to show creativity

and innovation, and giving students a sense of ownership of their learning.

It is in line with the above innovative attempts, this research was designed to see the

effect of GEBL on MTHE 2.

1.3 Aim

To assess the effect of GEBL approach, on Mechanical Engineering students’

understanding of MTHE 2.

1.4 Rationale and Problem Statement

In Higher Education Institutions (HEI’s) the achievement of course outcomes is the goal

of the institution and the reason for their being. Learning and teaching methods in

these institutions play a crucial role in the fulfilment of these goals.

Traditional teaching methods do not address individual needs in a diverse group and

this serves as a detriment to the learner (Felder & Silverman, 1988, p.674). According

to Gibson (2002, p.470), “a constructivist view of learning and a consequent move

away from the traditional chalk and talk teaching methods will benefit the student (and

society) through a recognition and development of his/her multiple intelligences”.

14

Gibson (2002, p.470) continues to state, “… that traditional teaching methods are

ineffective and, in any case, neither encourage nor measure student understanding

even when teachers think otherwise”. Most classes in engineering are auditory,

deductive and intuitive. However, many engineering students are visual learners (they

prefer to see diagrams, pictures, equipment and processes), and inductive and

sequential learners and these render an immediate mismatch between teaching and

learning styles (Kapadia, 2008, p.2). Different backgrounds and childhoods deliver

learners with different reference frameworks. The gaps and shortcomings among the

learners within the same group must be bridged by applying multiple teaching methods.

Engineers are required to do much more than just recalling formulas, substituting

values and finding answers. In their daily operations, they must be able to

communicate fluently, explain problems or situations clearly and analyse complex

problems, to name a few. These are skills that universities should aim to develop during

a student’s career so that the graduate is prepared for the industry. In order to achieve

this, a combination of teaching and learning methods which accommodate different

learning styles are necessary.

Over the past 17 years, the present researcher has observed a worrying trend with

decreasing throughput rates of the WSU NDME students as reflected in HEMIS, 2009.

The methods that are used to lecture to the students do not address the students’

needs and often new course materials are presented in a manner that make it

15

impossible for students to understand and follow. In Mechanical Engineering, the aim is

to produce graduates with problem solving skills, who can express themselves in

technical conversations and who can present themselves professionally as outlined in

the outcomes of the WSU NDME in chapter 2 pp.53-54. Achievement of these

characteristics was the inspiration to engage in a process of finding alternative methods

of presenting courses to them to check if the shortcomings of the current practices

could be addressed.

The problem is that the NDME students have difficulties in performing academically well

in the course. The study is focused on the effect of GEBL approach on students’

understanding of MTHE 2.

1.5 Theoretical Framework

The theoretical framework is based on active learning which subsumes cognitive

theories such as social constructivism and enquiry-based learning (EBL) theories.

Vygotsky was a social constructivist who believed that learners used the input of others

as they formulate their constructions and not relied solely on themselves. In Vygotskian

theory:

Learning is a social and collaborative activity;

Learners utilize the input of others;

These “others” include more importantly ‘significant others’ such as peers,

16

parents, friends;

Sources of information, such as the internet, books, videos and movies

also contribute to learning;

The teacher is the facilitator (Martin, 2009, p.214).

Figure 1.1: Modified Zone of Proximal Development (R.G. Tharp & R. Gallimore's, 1988, p.35)

Tharp and Gallimore (1988, p.35) draw from social constructivism to explain proximal

development. The zone of proximal development (ZPD) is defined as “the distance

between the actual development level as determined by independent problem solving

and the level of potential development as determined through problem solving under or

in collaboration with more capable peers” (Lipscomb, Swanson & West, 2004 cited in

Hardjito, 2010, p.131). Hardjito further states that “In the view of ZPD, the role of

teachers is to provide assistance or support to students with tasks that are just beyond

students’ current capability. When students’ gradually develop their mastery, teachers

17

start the process of ‘fading’, or gradual removal of the temporary support” (Lipscomb et

al., 2004 cited in Hardjito, 2010, p.131).

Reagan and Osborn (2002, p.60), explain that in social constructivism, which is the

alternative to radical constructivism, “... the process of knowledge construction

inevitably takes place in a socio-cultural context, and that therefore knowledge is in fact

socially constructed”. Fraser and Tobin (1997, p.8) explain that in social constructivism,

“... learning is not viewed as transfer of knowledge but the learner actively

constructing, or even creating, his or her knowledge on the basis of the knowledge

already held”. Active teaching and learning methods are based on social constructivism

as appose to behaviourism. Behaviourism is a more teacher-centred approach, where

student performance directly depends upon teacher performance. According to Jones

and Brader-Araje (2002, p.1) behaviourism “... placed the responsibility for learning

directly on the shoulders of teachers”. Yaman (2005, p.25) explains further:

... people may react to the same information in very different ways while

learning. Importantly, constructivism sees learning as an internal process of

interpretation, rather than a process of knowledge transmission. In this point, we

should distinguish constructivism from behaviourism. In behaviourism, learning is

seen as the conditioning of human behaviour through habit formation. It implies

the dominance of the teacher, with learners characterized as essentially passive,

which constructivism strongly disagrees.

18

De Graaf, Saunders-Smits and Nieweg (2005, p.38) state that “... students bring to

their learning understandings (and misunderstandings), skills and propensities to

behave in certain ways, and that they build upon them or modify them in learning

situations; construct new understandings, skills and behaviours”. Adams, Kaczmarczyk,

Picton and Demian (2007, p.2) explain in the context of Bloom’s taxonomy, “... the

higher level cognitive skills of analysis, synthesis and evaluation are relevant to our

ability to effectively solve problems. The effective development of these skills, however,

requires mediation”. According to Ma (2009, p.164) in active learning, “... high levels of

social interaction and collaboration contributed to the establishment of a community of

learning, nurturing a space for fostering higher order thinking through co-creation of

knowledge processes”. Pundak, Herscovitz, Shacham and Wiser-Biton (2009, p.226)

state that “... one of the major goals of science and technology education today is to

promote students' active learning as a way to improve students' conceptual

understanding and thinking skills”.

The core ingredients of an EBL approach that some researchers are in agreement with

are: learning is stimulated by enquiry, i.e. driven by questions or problems; learning is

based on a process of seeking knowledge and new understanding; a learning-centred

approach to teaching in which the role of the teacher is to act as a facilitator; a move to

self-directed learning with students taking increasing responsibility for their learning and

the development of skills in self-reflection; an active approach to learning (Spronken-

Smith, et al., 2007, p.2). Geer and Rudge (2004, p.3) state:

19

... knowledge is fluid, not static; therefore, instructional practices reiterating

knowledge as static should not be promulgated as sole efficacious pedagogy,

because such instructional practices serve to tacitly inform future generations of

ill-conceived notions regarding science and knowledge of the world within the

disciplines it encompasses.

Social constructivism and its impacts on student learning therefore are adopted as the

main theoretical framework for this study.

1.6. Research Questions

1.6.1 What would be the effect of a guided enquiry-based learning (GEBL) approach

on mechanical engineering students’ factual recall of MTHE 2 concepts?


on mechanical engineering students’ conceptual understanding of MTHE 2

concepts, principles and applications?


on mechanical engineering students’ ability to communicate procedures and

processes related to MTHE 2?

1.6.4 To what extent would the formulation and use of key performance indicators

(KPIs) be an effective tool for ascertaining students’ attainment of desired

educational outcomes in MTHE 2?

20

1.7 Objectives

1.7.1 To investigate the effect of a guided enquiry-based learning (GEBL) approach on

mechanical engineering students’:

1.7.1.1 ability to recall factual information related to the topic: thermodynamics;

1.7.1.2 conceptual understanding of thermodynamics concepts, principles and

applications;

1.7.1.3 ability to communicate procedures, processes and applications related to

thermodynamics.

1.7.2 To apply the principle of key performance indicators (KPIs) as a tool for

ascertaining students’ attainment of intended educational outcomes in

thermodynamics.

1.8 Significance of the Study

The students can benefit from an investigation into improved teaching methods.

Students can be better prepared for their future careers which will result in more

productive engineers and technicians entering the industry. Most of these students have

a disadvantaged background and are therefore battling even more with the rapidly

developing technology. A different approach to address these shortcomings if more

effective and efficient than the present more traditional methods will definitely lay a

sound foundation and build a proper framework for future reference as suggested by

Strangman and Hall (2004, p.1).

21

Students in other engineering courses at WSU and students from other Institutions can

benefit from the findings of this study. Being able to come up with a solution to the

problem or to improve student performance and delivering a graduate more ready for

employment by industry will definitely be welcomed by all.

1.9 Methodology

This study was a Participatory Action Research (PAR) with the researcher (change

agent) being part of this study through his academic responsibility for MTHE 2. The

purpose of this study was to assess the effect of GEBL approach on Mechanical

Engineering students’ understanding of MTHE 2. The intervention was then reviewed

and evaluated to improve the manner in which MTHE 2 was presented to students. The

focus was to empower students and measure students’ performance not just in terms of

academic scores but also in the development of multiple skills necessary for an

engineering career. The achievement of outcomes in MTHE 2 was also measured to

determine the extent to which this intervention assisted in achieving these outcomes.

1.9.1 Research Subjects

It was made up of 20 students registered for MTHE 2 at WSU Chiselhurst campus in

East London out of a population of 40. The sample consisted of fulltime students who

voluntarily agreed to participate in the GEBL.

22

1.9.2 Instrument and Data Collection

Both quantitative and qualitative data were collected. The semester tests, oral test, final

examination and structured questionnaire were used to gather the quantitative data.

The interviews were used to gather the qualitative data.

The instruments were three formative assessments, an oral test, summative

assessment, KPIs, a structured questionnaire and interviews. The three formative

assessments and the summative assessment were designed to test not only analytical

abilities but also the students’ understanding, interpretation and analysis of questions.

The oral test was designed to determine the students’ knowledge on certain aspects of

MTHE 2 course content. Key performance indicators were developed to measure the

extent to which the course outcomes were achieved. These indicators were designed to

measure the selected outcomes which were relevant to this course. The structured

questionnaires were used to measure the students’ rating of various aspects of the

intervention. This was designed to gather quantitative responses from the students

regarding their experience with GEBL. Finally, students were also interviewed to gather

qualitative data on their experiences and opinions on this alternative presentation of

MTHE 2.

1.10 Limitations and Delimitations of the Study

1.10.1 The students’ social and economic backgrounds were not considered, although

23

they were recognized that these factors may have an influence on their academic

performance.

1.10.2 These students had all passed the pre-requisite for this course and were starting

their second semester. Secondary schools attended were therefore not

considered.

1.10.3 The study did not consider factors such as lighting, ventilation, indoor air quality

and acoustics.

1.10.4 The students’ commitment during the semester could influence the study and

everything possible was done to ensure that they stayed committed.

1.10.5 The student’s attitude could influence the study and everything possible was

done to ensure that all subjects in the sample had a focused and positive

attitude.

1.10.6 In order to avoid the research bias, interviews were done by a person who

qualified both as an insider and an outsider as explained in this document. This is

a delimitation.

1.10.7 The venue suitable and available for group sessions could only accommodate 20

students.

1.11 Definitions of Terms

A number of terms are defined to assist the reader in understanding the specific context

and meaning in which they appear and are used in this document.

24

Active Learning – “... an instructional method which engages students in the learning

process. In short, active learning requires students to do meaningful learning activities

and think about what they are doing” (Prince, 2004, p.223).

Guided Enquiry Based Learning – “... refers to an array of classroom practices that

promote student learning through guided and, increasingly independent investigation of

complex questions and problems. Rather than teaching the results of others'

investigations, which students learn passively, instructors assist students in mastering

and learning through the process of active investigation itself” (Lee, 2004, p.9).

Enquiry – “... generally refers to a process of asking questions, generating and pursuing

strategies to investigate those questions by generating data, analyzing and interpreting

those data, drawing conclusions from them, communicating those conclusions, applying

conclusions back to the original question, and perhaps following up on new questions

that arise” (Krajcik et al., 1998; NRC, 1996; White & Frederiksen, 1998 cited in

Sandoval, 2005, p.635).

Inductive Learning – “... effective instruction must set up experiences that induce

students to construct knowledge for themselves, when necessary adjusting or rejecting

their prior beliefs and misconceptions in light of the evidence provided by the

experiences” (Prince & Felder, 2006, p.126).

25

Outcomes – “Anticipated or achieved results of programs or the accomplishment of

institutional objectives, as demonstrated by a wide range of indicators such as student

knowledge, cognitive skills, and attitudes” (Vlasceanu, Grunberg & Parlea 2007, p.63).

Key Performance Indicators (KPIs) – “A range of statistical parameters representing a

measure of the extent to which a higher education institution or a program is

performing in a certain quality dimension” (Vlasceanu et al., 2007, p.60).

Traditional Teaching and Learning – “Traditional instruction in engineering and science

frequently treats new courses and new topics within courses as self-contained bodies of

knowledge, presenting theories and formulas with minimal grounding in students’ prior

knowledge and little or no grounding in their experience” (Prince & Felder, 2006,

p.125).

University of Technology – Former Technikons in South Africa, now being renamed

Universities of Technology, are higher education institutions that provide and promote,

in co-operation with the private and public sectors, quality career and technology

education and research for the developmental needs of a transforming South Africa and

the changing world. As institutions of technological higher education, their tertiary

educational programmes cover a variety of specialised occupations and careers in the

applied engineering; biological, chemical and physical sciences; and applied commercial

sciences; humanities, arts and teacher education (Committee of Technikon Principals

26

(CTP), 2001, p.1).

1.12 Organisation of the Thesis

Chapter 1

In this chapter a background to the study was given, highlighting the problems that

engineering education experiences globally and the reasons for this research. The

problem statement, objectives of the study, theoretical framework, research question

and sub-questions, significance of the proposed study, limitations and delimitations and

rationale were presented and explained. A list with definitions of pertinent terms used,

were listed.

Chapter 2

In this chapter the literature related to this study is cited. The terms effective teaching

and significant learning are also discussed. The reason for selecting GEBL is also

explained. A definition of outcomes and the particular outcomes for NDME as specified

by SAQA is discussed and from these outcomes certain outcomes are selected which

applies to MTHE 2.

Chapter 3

In this chapter the methodology is discussed. The modes of enquiry are explained as

well as the population and sample. A detailed explanation and discussion of how the

intervention was introduced is given as well as a detailed description of how the

instruments were used to assess the students. Specific KPIs which were developed to

27

address the achievement of the selected outcomes for MTHE 2 are given.

Chapter 4

In this chapter the data collection, data analysis, interpretation and discussions are

given. The findings from the data and its meaning to engineering education are also

elaborated on. The evidence gathered from this data is discussed in detail and

arguments are made, based on this data. Lessons learned from the research and the

impact it had on Thermodynamics 2 education at WSU are also discussed.

Chapter 5

In this chapter conclusions are drawn from the results of the study. The effect that

GEBL had on student learning in terms of test and examination scores as well as the

development of multiple skills such as communication, team work, the improvement of

technical vocabulary and responsibility developed towards their own studies will be

highlighted. Recommendations based on these findings are made for future

consideration and implementation within the Mechanical Engineering Department of

WSU. A model is proposed for MTHE 2 and a general model is proposed for other

mechanical engineering courses.

1.13 Summary

In the introduction and background to this study, a need for this investigation was

established. The aims and objectives were stipulated which indicated that a more

28

effective method of teaching and learning engineering students needed to be developed

and the impact of these methods on student learning would be evaluated. The problem

statement highlighted the shortcoming of current teaching and learning practices at

WSU. The epistemological approach to acquiring knowledge will be active learning and

social constructivism. It was indicated under the research questions that the effect of

GEBL approach on mechanical engineering students’ ability to recall factual and

conceptual knowledge and communicate procedures and processes in MTHE 2 will be

investigated. The significance of this study was to ultimately develop an effective

teaching and learning method to benefit the students.

The research was PAR with group sessions to deal with course content and the

instruments were formative assessments, an oral test, a summative assessment, a

structured questionnaire and an interview. Both qualitative data and quantitative data

were collected and studied. Certain limitations and delimitations were listed which could

have impacted on the study. A brief rationale was given to indicate to the reader what

inspired the researcher to undertake this study. Definitions of important terms used in

this study were also given to clarify the use of these terms and their meaning in the

context of this study. The organisation of this study was given to briefly indicate to the

reader the various chapters and the information each one deals with.

29

CHAPTER 2

LITERATURE REVIEW

This chapter reviews pertinent literature for this study to address the themes suggested

by research objectives. In addressing the themes of the first three objectives, the focus

will be on social constructivism, inductive/deductive teaching and learning and research

where active learning, EBL and GEBL in engineering were used and the findings from

such reports. Kolb’s Learning Cycle, Bloom’s Taxonomy (Cognitive Domain), effective

teaching and significant learning will also be discussed as well as the meaning of deep

and surface learning and how it assists student development. In addressing the fourth

theme, SAQA and ECSA’s views on outcomes will be presented and KPIs to measure

these outcomes will be discussed. This review will seek to indicate how the research

objectives can be addressed by different teaching and learning styles and how different

approaches and strategies can influence learning experiences.

2.1 Social Constructivism in Education

Social constructivism has many applications in education. This section will look at

research done with social constructivism as the underpinning theory and its impact on

teaching and learning in engineering education. On social constructivism, Hyslop-

Margison and Strobel (2008, p.84) state, “Through language acquisition and guided

30

instruction, then, Vygotsky’s model of social constructivism leads students toward

educational objectives designed to provide them with certain crucial forms of social and

cultural knowledge”.

Social constructivism is widely used in engineering education by researchers (Nicol &

Boyle, 2003; Ferreira & Mueller, 2004; Michaelides, Eleftheriou & Muller, 2004; Brodie &

Gibbings, 2007) as the epistemology of how knowledge is acquired. A study done on

students in an Engineering Mechanics course, used activities called Active Learning

Products (ALPs) to engage the students in a more active learning process. These ALPs

were situated within social constructivism and results indicated that it improved student

learning and that the students needed more learning activity in courses (Linsey, Talley,

White & Jensen, 2009, pp.18-19). According to Kitto (2010, p.S3G-6) in a research

done in Material Engineering course, “... the improved outcomes were all based on the

basic principles of social and cognitive constructivism”. Kitto further explains that “...

collaboration improves outcomes, especially in higher order thinking skills, on term-long

research papers”. Constructivism in general and social constructivism in particular argue

for learning processes which include individual learning, active participation by the

learner and collaborative learning as suggested by Reagan and Osborn (2002, p.59).

2.2 Active Learning

Active learning is learning with understanding. It is enhanced by learning through

activity. This means that the students are using more senses and that there is

31

interaction between them and the information in the form of discussions, exchanging of

ideas and sharing of views. According to Prince (2004, p.223) the definition of active

learning is, “... any instructional method which engages students in the learning

process. In short, active learning requires students to do meaningful learning activities

and think about what they are doing”.

Felder and Brent (2003, p.282) suggested that active learning may increase the

performance percentage, and simultaneously work well even in large groups despite the

difficulty to get most of the students actively involved in the process. The advantage of

social learning too kicks in. Furthermore, as Felder and Brent (2003, p.282) emphasise,

a self study session even for a few minutes during the lecturing session, may inspire

students on the topic under discussion and motivate and stimulate student

participation.

Although active learning is rather a fairly new method of teaching and learning process,

this move away from the traditional ‘chalk and talk’ and lecturer-centred approach, has

already proven to be more fruitful. The more the students are actively involved with the

learning process, the more they will want to experience, find out, discover, learn,

realise and understand the concepts. Above all, many engineering principles which are

usually difficult to comprehend become easier to handle. The Board of European

Students of Technology (BEST), (2006, p.6) corroborates the above view.

32

Prince (2004, p.229), based on his study on active teaching methods, states that “...

this study has found support for all forms of active learning examined”. Prince (2004,

p.229) continues, “... students will remember more content if brief activities are brought

into the lecture”. In Introductory Thermodynamics, where Computer-based Instruction

(CBI) was used as an intervention, Anderson, Taraban and Sharma (2005, p.1168)

state, “We believe that a current challenge in engineering education is to develop active

learning exercises that are simple, relate to the learner's experience level, and that can

be incorporated into and synchronized with other teaching pedagogies”. In a study at

Purdue University College of Technology, United States of America (USA), it was

claimed that the data collected from an active learning experience in Mechanical

Engineering Technology course “... clearly showed evidence of increased learning with

the active learning elements” (Fuehne, 2007, p.6).

In Australia, Junglas (2006, p.175) introduced active learning into a Thermodynamics

class and found that “... students gained a better understanding of thermodynamic

processes and achieved higher scores in the final examinations”. In Saudi Arabia a

study done with active learning tools in a Thermo-Fluid course created the opportunity

for, “... discussion boards that allow for student interaction among themselves... it has

elements of critical thinking, discussions and deliberation of various course elements...

This helped actually to motivate the students to further explore various aspects of

thermo-fluid problems”. This view was also supported by (Zubair & Antar, 2004, p.4).

According to De Weck, Young and Adams (2003, p.11), with regard to an active

33

learning approach at the Massachusetts Institute of Technology, USA, “Presenting

problems in such an active learning format enabled us to address secondary learning

objectives such as technical communications, system modelling and qualitative

estimation”.

In the Mechanical Engineering Department of North-West University (NWU), Pair

Problem Solving (PPS) was used as a co-operative learning strategy to enhance the

conventional teaching method which was used to offer Thermodynamics. During

interviews, students indicated that PPS improved their understanding of

Thermodynamics (van Niekerk, Mentz & Smit, 2011, p.178). At the Witwatersrand

University (WITS), an alternative teaching approach was introduced and this was

according to Woollacott (2011, p.322):

... an innovative, active-learning methodology termed mediated-interaction-

groups or MIGs for the enhancement of learning by means of students

articulating their ideas and thinking in an interactive learning environment

which is strongly mediated by a knowledgeable facilitator.

34

Table 2.1 gives a summary of some active learning methods.

Method Feature

Enquiry Problem

based

Project

based

Case

based

Discovery JiTT

Questions or problems provide context

for learning

1 2 2 2 2 2

Complex, ill-structured, open-ended

real-world problems provide context

for learning

4 1 3 2 4 4

Major projects provide context for

learning

4 4 1 3 4 4

Case studies provide context for

learning

4 4 4 1 4 4

Students discover course content for

themselves

2 2 2 3 1 2

Students complete & submit

conceptual exercises electronically;

instructor adjusts lessons according to

their responses

4 4 4 4 4 1

Primarily self-directed learning 4 3 3 3 2 4

Active learning 2 2 2 2 2 2

Collaborative/cooperative (team-

based) learning

4 3 3 4 4 4

1 – by definition, 2 – always, 3 – usually, 4 – possibly

Table 2.1: Features of Common Inductive Instructional Methods (Prince & Felder, 2006, p.125)

35

2.2.1 Enquiry Based Learning (EBL) and Guided Enquiry Based Learning

(GEBL)

EBL is also referred to as research-based teaching, inductive learning and teaching or

discovery learning. There is some agreement with regard to what will form the core

ingredients of an EBL approach and the main factors are:

EBL stimulates the learning process;

Students experience learning through their actions of investigating, discovery and

understanding;

EBL shifts the emphasis to the student with the lecturer merely facilitating the

process;

EBL puts the responsibility on the student who must take charge of his/her own

learning;

EBL is active involvement in learning on the students’ behalf making it definitely a

more active process (Spronken-Smith, et al., 2007, p.2).

Prince and Felder (2006, p.124) explain that the, “... support for the use of EBL comes

from the strong theoretical underpinning of the approach including constructivism,

cognitive research on motivating learners, intellectual development and approaches to

learning”.

36

Lee (2004, p.1) states that EBL also promotes:

... the ability to formulate good questions, identify and collect appropriate

evidence, present results systematically, analyse and interpret results, formulate

conclusions and evaluate the worth and importance of those conclusions. It may

also involve the ability to identify problems, examine problems, generate possible

solutions, and select the best solution with appropriate justification.

There is however a negative attitude towards EBL approach which is driven by the

perception that it requires more work. However, lecturers can also benefit from EBL

through the enhanced active involvement and interaction with students and

incorporating theoretical lectures with research engagement, still some lecturers may

find a paradigm shift very difficult (Spronken-Smith, et al., 2007, p.4). In a study done

with EBL in a Engineering Mechanics course, Miller–Young (2007, p.9) states that “...

this project incorporated all the principles for supporting critical thinking, and stimulated

student interest in the course as well as engineering in general”. Hanson (2006, p.3)

states in an Instructors’ Guide to Guided-Oriented Process Enquiry Learning (POGEL)

that “To support this research-based learning environment, POGEL uses learning teams,

guided enquiry activities to develop understanding, questions to promote critical and

analytical thinking, problem solving, reporting, meta-cognition, and individual

responsibility”.

37

Prince and Felder (2006, p.134) state that “... enquiry learning is the simplest of the

inductive approaches and might be the best one for inexperienced or previously

traditional instructors to begin with”. Edwards and Recktenwald (2008, p.8) explain that

“... guided enquiry learning provides a rich environment for enhancing the learning

experience”. Edwards and Recktenwald (2008, p.8) continues to state, that the GEBL

experiences were, “... giving them more exposure to the topics than they would

otherwise get from a traditional lecture format”.

Charelvoix, Strey and Mills (2009, p.25) explain that:

... the multi-media, coupled with the guided enquiry activity worksheets,

provided students with a tangible way to engage the material as well as provided

a break from the typical college-course format. Students were given the valuable

opportunity to work on activities and discuss them with their peers, broadening

their understanding by engaging in a dialogue that required them to explore

other students’ interpretations of the situation. The in-class learning activities

were also an opportunity for students to directly interact with the professor and

teaching assistants.

Research done in a science class based on GEBL found that students understood

concepts explained to them better. There was also sufficient evidence that the

classroom discussions and the science notebooks used as part of the GEBL approach

38

assisted students in achieving a deeper understanding of course content and also

developed complex reasoning abilities (Klentschy & Thompson, 2008, p.7). GEBL has

been used widely by researchers as an alternative pedagogy to offer courses in

engineering education in an attempt to make teaching more effective and to improve

student learning (Thompson, Alford, Liao, Johnson & Matthews, 2005; Donath, Spray,

Thompson, Alford, Craig & Matthews, 2005; Richards & Schnittka, 2007; Taraban,

Anderson, De Finis, Brown, Weigold & Sharma, 2007).

2.3 Inductive and Deductive Teaching and Learning and Learning Styles

The following section deals with inductive and deductive teaching and learning and the

different learning styles.

2.3.1 Inductive and Deductive Teaching and Learning

Inductive teaching presents a student with a problem which must be solved and as the

student works through the problem he/she will learn the principles, rules, procedures

and theories related to the problem. In deductive teaching and learning, the student is

first supplied with principles and theories and is later introduced to their application.

The method of Inductive teaching and learning places more emphasis on the student. It

involves the student in the learning process through asking questions, investigating

problems, discussions in groups and conducting research. Prince and Felder (2006,

p.125) corroborate this view. An inductive teaching and learning approach is being used

39

more and more as an alternative to traditional deductive teaching by researchers

(Hesketh, Farrell & Slater, 2002; Kitto, 2009; McKenna, Yalvac & Light, 2009; Felder &

Brent, 2010) in engineering education to enhance teaching practices, improve student

learning and to develop multiple skills. Elshorgaby and Schonwetter (2002, p.297) state

that “The most prevalent form of teaching is still the traditional lecture, or deductive

instruction ... this format of instruction is the least effective in promoting learning”.

In engineering education, where a heat and mass transfer course was presented to

students in an inductive manner, Farrell and Hesketh (2000, p.3) state, “We have found

that this inductive approach to heat and mass transfer has naturally created

opportunities for active learning via laboratory experiments and in-class discussions of

experimental observations, thus contributing further to students’ understanding and

retention of new material...” Bardet and Ragusa (2009, p.2) explain that “Inductive

teaching refers to pedagogical approaches that include active engagement by students

in collaborative problem solving rather than disengaging lecturing, which is the

traditional pedagogical approach of engineering education”.

The School of Mechanical and Nuclear Engineering at the NWU in SA changed their

conventional didactic approach to a group project-based inductive learning approach

which resulted in positive feedback with regard to stimulation of interest, increased

ability to do research, enhancing professional engineering competencies in terms of

report writing and audiovisual presentation and debating skills (Serfontein & Fick, 2011,

40

p.183).

2.3.2 A Spectrum of Learning Styles

Previous studies have also shown that learning styles play a very important role in how

information is presented by a lecturer and how that information is perceived by the

learner. Many researchers (Goldfinch, Carew & McCarthy, 2008; Kapadia, 2008;

Lamancusa, Zayas, Soyster, Morell & Jorgensen, 2008; Naher, Brabazon & Looney,

2008; O’Dwyer, 2008) have investigated the importance of teaching and learning styles

on engineering students’ academic performance. They have found that learning styles

and the teaching styles have a direct influence on students’ learning. Reid (2005, p.21)

states that “... learning styles can therefore be a vehicle for ensuring that the

individuality of all learners is paramount, particularly in an inclusive educational

environment”.

In a study conducted at the Dublin Institute of Technology on learning styles of first

year mechanical and electrical students, O’Dwyer (2009, p.5) concludes, “... it is

desirable to create an overall learning environment across all subjects to appeal to as

wide a range of learning styles as possible”. If lecturers (teachers) know about the

different learning styles and where their own learning style fits in the spectrum of

learning styles, it will help them to recognise and accommodate students with different

learning styles. It will help in the way they present a lecture to cater for various

learning styles. It will also improve student learning when information is presented to

41

them in a manner that falls in line with their learning styles (Davis, 1993, p.189).

Felder, Woods, Stice & Rugarcia (2000, p.33) state that:

Most intuitive professors and even many of the sensing professors teach in an

intuitor-oriented manner, emphasizing theories, mathematical models and

abstract prose to students who respond best to concrete examples, well-

established problem-solving procedures... This mismatch has several

unfortunate consequences for the sensing learners.

2.4 Effective Teaching

Alternative non-traditional methods of course presentations are being considered by

researchers to improve the effectiveness of presentations which, in turn, can promote

student learning and the development of skills in various engineering courses (Ditcher,

2001; Qualters, Sheahan, Mason, Navick & Dixon, 2008; Su, 2008; Felder et al., 2010).

Effective teaching and learning can be achieved by focusing on the following points

during preparation and presentation of a lecture, as presented by Carbone, Conway and

Farr (2004, p.3):

Strategic preparation, Tactical Preparation, Mental Preparation, Delivery,

Enthusiasm, Relationship with the class, Demonstrating and encouraging

competency, Clarity, Humour, Jargon, Understanding the students’ context,

Linking, Metaphors, Teaching inductively and Interaction.

42

Killen (2006, p.3) lists in his book the effective teaching strategies which indicate that

high quality learning has occurred:

students are able to apply their knowledge to solve problems;

students are able to communicate their knowledge to others;

students are able to perceive relationships between their existing knowledge and

the new thing they are learning;

students retain newly acquired knowledge for a long time;

students are able to discover or create new knowledge for themselves;

students want to learn more.

To teach higher order thinking in a classroom as part of effective teaching strategies,

students must be made aware of how to focus at all times in lectures. The lecturer must

therefore instruct the class in a way that will encourage the students to think more

effectively. Active teaching and learning methods engage students more directly and

effectively in their learning process and will assist the lecturer in presenting material to

the students in a manner which will be more effective than the traditional teaching

(Orlich, Harder, Callahan, Trevisan & Brown, 2010, p.288).

Students must make use of the correct learning strategies to achieve effective learning.

Learning strategies can involve any activity which the students use to achieve a learning

goal e.g.; cognitive, meta-cognitive, motivational and affective. Cognitive strategies can

43

be rehearsal, elaboration and organisation. Rehearsal helps the student’s attention and

the ability to encode information. Elaboration helps the student to improve his/her long-

term memory and to make a connection between existing (old) and new information.

The student uses what he/she already knows to understand the new information.

Organisation helps the student to select appropriate information and to make a

connection between the parts of the information (De La Harpe & Radloff, 2007, pp.2-3).

2.5 Significant Learning

In this section Fink’s (2003) taxonomy of significant learning will be discussed as well as

the requirements for learning to be regarded as being significant is explained. There is

a clear connection between the active teaching and learning process and the different

areas of development which defines significant learning. Fink in his ‘taxonomy of

significant learning’ defined various aspects of personal development which will result in

significant learning taking place to a more or lesser degree.

‘What is significant learning?’ - It is a learning process that consists of one or more of

the following six kinds of learning:

Foundational knowledge: this is basic knowledge that the students have about

a specific topic or area, which will in turn assist them in their learning of further

aspects of that particular topic or area. More complex learning will therefore be

enhanced by the prior knowledge;

44

Application learning: here the student must be able to learn how to think for

example critically and practically from a safety point of view. Application goes

hand-in-hand with the development of skills such as communication;

Integration: here the student is able to make a connection between what has

been taught in class and the practical application or significance of it in

engineering. The student can relate the theory to practical applications and will

therefore realise the value of what has been taught;

The Human dimension of learning: the student realises how he/she is learning.

The student can also come to realise how other students interpret or understand

a problem or how they approach a problem;

Caring: the student changes his/her ‘attitude’ about something and start caring

more for something e.g., if a student understands a particular course he/she will

spend more time on it;

Learning how to learn: the student learns something about the process of

learning. For example, the student learns how to analyse a problem by following

a certain process, or the student learns how to analyse a problem through an

enquiry process Fink (2003, pp.4-6).

Fink (2003, pp.7-8) further states that “... the more that these kinds of learning occur,

the more significant the learning experience is. In fact, the most significant kind of

learning experience is one in which students achieve all six kinds of significant

learning”.

45

2.6 Deep and Surface Learning

In research done in engineering education Ditcher (2001, p.25) explains that:

Two main categories of learning have been identified: a deep approach and a

surface approach. In a deep approach of learning, the student is looking for

underlying meaning and structure and taking a holistic view. In contrast, a

surface approach focuses on discrete pieces of knowledge, without attempting to

integrate them.

According to Mazumder (2010, pp.1-2):

... An important characteristic of successful students is that they are capable of

assessing and regulating their own learning behaviour. They strive for deep

understanding and assess how well they know the material in addition to what

they learned. They demonstrate higher levels of confidence in their knowledge

that can only be achieved by deep learning, rather than the surface learning by

some of their peer students.

2.6.1 Deep Learning

Researchers in engineering education make use of various interventions in an attempt

to achieve deep learning in their course offers. This will result in the development of

46

multiple skills necessary for the profession (Qualters, 2008; Felder, 2010; Litzinger,

Lattuca & Hadgraft, 2011).

In China, an electrochemistry course was offered using a more student-centred

approach. Ying (2003, p.44) suggests that “... we need to change our teaching

approach from a teacher-centred model to a more student-centred one in order to

encourage our students to adopt a deep level approach to their learning, and to

encourage them to master a competence in problem solving”. Fowler (2004, p.72)

states in her dissertation that “The results of the data regarding retention and the

approach to learning indicated a very strong trend toward higher retention for students

with a deeper approach to learning and lower retention for students with a surface

approach to learning”.

Case and Marshall (2009, p.11) explain in her study on deep and surface learning that

“The deep approach is defined by a search for understanding, using whatever

strategy...” While comparing the achievement of learning outcomes, Case and Marshall

(2009, p.13) state, “Students who were identified as using a deep approach were also

seen to have qualitatively superior learning outcomes, as well as greater recall of facts”.

In summary Cope (2003, p.415) states, “Only deep learning approaches have been

associated with the development of deep levels of understanding”. Lublin (2003, p.3)

explains that “Students who take a deep approach have the intention of understanding,

engaging with, operating in and valuing the subject...” Robbins and Ardebili (2006, p.6)

suggest that “Engineering students need effective problem-solving abilities and these

47

come by deep conceptual understanding of the fundamental physical understanding”.

In the USA, Rose, Kumar, Aleven, Robinson and Wu (2006, p.8) found that “... the

student has the potential to gain a deeper understanding of the design space and

underlying thermodynamics principles...” using an active learning approach by creating

a simulation based exploratory learning environment.

2.6.2 Surface Learning

Surface learning does not link new knowledge to prior knowledge and it replaces one

set of knowledge with another without actually understanding it (Hay, 2007, p.50).

According to Floyd, Harrington and Santiago (2009, p.187):

... a surface learning strategy is a survival technique – the student is simply

trying to pass the course with minimal effort. Since engagement has no

relationship to a surface learning strategy, whereas perceived course value does,

the importance of course value in getting the unmotivated student to expend

effort to go beyond surface learning is an important finding of this study.

Lublin (2003, p.4) suggests that:

Students who take a surface approach tend not to have the primary intention of

becoming interested in and of understanding the subject, but rather their

48

motivation tends to be that of jumping through the necessary hoops in order to

acquire the mark, or the grade, or the qualification.

Maier, Barnett, Warren and Brunner (1998, p.23) explain that “Surface learning, as the

name suggests, applies to learning where the student takes on board ideas from the

teacher, but does not ‘translate’ or adapt those ideas in any way”. McKenna et al.

(2009, p.19) state that “Students with surface learning approaches are more likely to

have negative attitudes toward learning”. According to Armarego (2007, p.4),

... Those with a surface orientation tend to take an approach characterised as

instrumental, reproductive and minimalist, relying on rote memorisation and

mechanical formula substitution, making little or no effort to understand the

material being taught.

2.7 Kolb’s Learning Cycle

According to Nilson (2010, p.231) Kolb’s learning cycle, “... portrays the process of

meaningful learning as a series of events that integrates the functions of feeling,

perceiving, thinking and acting”.

49

Concrete Experience

CE - (Feeling) Active Experimentation Reflective Observation AE - (Doing) RO - (Watching)

Abstract Conceptualization AC - (Thinking)

Figure 2.1: Movement through Kolb’s Learning Cycle which can be enhanced by Active Learning

According to Kuri (2000, p.5) Kolb’s learning cycle as illustrated in figure 2.1, “...

increases the students' motivation with learning styles that are not assisted by the

lecturing”. Kuri (2000, p.5) continues to say that:

... the model here described supplies that opportunity, because besides helping

the students become independent, it stimulates the reasoning, the development

of the necessary abilities for the resolution of problems and the communication

to each apprenticeship of the cycle. The problem solving promotes the

development of analysis abilities, synthesis and evaluation, abilities which are not

encouraged by lecturing, but that are clearly necessary in the engineering

teaching.

What if? Why?

Accommodators Divergers

(Do and feel) (Feel and watch)

How? What?

Convergrers Assimilators

(Think and do) (Watch and think)

50

Kolb’s Learning Cycle Engineering Education Process/Activity

Concrete Experience

Having an experience

(Demonstration of boiler plant operation)

Reflective Observation

Reflecting on the experience

(Comments, feedback, discussions)

Abstract Conceptualization

Learning from the experience

(Boiler plant theory, literature, diagrams)

Active Experimentation

Apply what has been learnt

(New approach to addressing plant problems)

Table 2.2: Kolb’s Learning Cycle and Engineering Education Activities

Table 2.2 illustrates the movement through Kolb’s learning cycle in engineering

education.

51

Movement through Kolb’s Learning

Cycle

Teaching and learning process/activity

Concrete Experience - Reflective Observation

(Why do I need to know this?)

Demonstration

Introduction and explanation

Reflective Observation - Abstract

Conceptualization

(What do I need to solve this?)

Lectures

Learning concepts, principles and theories

Abstract Conceptualization - Active

Experimentation

(How can I solve this?)

Doing

Experimenting with concepts

Practicing problem solving

Active Experimentation - Concrete Experience

(What if I use this approach?)

Using

Applying what have been learned to new

problems

Table 2.3: Movement through Kolb’s Learning Cycle with Teaching and Learning Activities

Kolb’s learning cycle is widely used as pedagogy for teaching students engineering in

courses. Researchers in engineering education (Ogot & Okudan 2006; Kapranos, 2007;

Aziz & Chassapis, 2008; Altuger, Tumkor & Chassapis, 2009; Stappenbelt, 2010) use

the movement through Kolb’s cycle to plan and structure course presentation to

students. Elshorbagy and Schonwetter (2002, p.297) suggested that if engineering

students can be taught in a manner which promotes the movement through Kolb’s

learning circle, “... students can retain this knowledge for longer periods of time and

apply it to different cases and in different situations. This is ideal for the training future

52

engineers”.

2.8 Bloom’s Taxonomy (Cognitive Domain)

Bloom’s taxonomy on how we learn presents different hierarchical levels of learning,

starting from low at the bottom to high at the top. The lower level has to occur before

the next higher one can be achieved and progressively the learner will work his/her way

through the different levels from ‘knowledge’ > ‘comprehension’ > ‘application’ >

‘analysis’ > ‘synthesis’ > ‘evaluation’. Rutkowski, Moscinska and Jantos (2010, p.2)

listed the six levels in Bloom’s cognitive domain with equivalent key words as follows:

1. Knowledge: define, list, name, order, recognize, relate, recall, repeat,

2. Comprehension: classify, discuss, explain, identify, indicate, report, review, select,

3. Application: apply, choose, demonstrate, sketch, solve, use, write,

4. Analysis: analyze, calculate, compare, contrast, discriminate, examine, experiment,

5. Synthesis: assemble, construct, create, design, develop, formulate, prepare,

propose, write,

6. Evaluation: assess, attach, choose, compare, predict, rate, select, evaluate.

Many researchers use Bloom’s taxonomy in engineering research to improve, gauge and

evaluate course offerings to students (Terry & Harp, 1993; Reeves, Courter, Nickels,

Noyce, Pearce, Schaefer, Wickramasinghe & Lyle, 1998; Prince & Hoyt, 2002;

Elshorbagy & Schonwetter, 2002; Hopson, Simms & Knezek, 2002; Żywno, 2003; Boles,

53

Beck & Hargreaves, 2005; Uziak, Oladiran & Moalosi, 2010). The various levels in

Bloom’s cognitive domain of educational activities are seen to be important for the

development of critical thinking skills and the enhancement of learning outcomes in

engineering education. This view is corroborated by Boles et al. (2005, p.3). With

regard to the cognitive objectives of Bloom’s taxonomy, Irish (1999, p.84) states that

“Ideally, engineers need to function at all levels”. The effectiveness and impact of

interventions in mechanical engineering education are also used in conjunction with

Bloom’s taxonomy. Researchers make extensive use of the lower and higher order

thinking skills in the cognitive domain to determine the success of their intervention in

terms of student learning and achievement (Kaw, Besterfield & Eison, 2005; Craig,

Joines, Miller, C., Miller, T., Raubenheimer, Rouskas, Silverberg & Wiebe, 2008; Castles,

Lohani & Kachroo, 2009; Kaw & Garapati, 2010).

2.9 Outcomes and Key Performance Indicators

2.9.1 Outcomes

‘Outcomes’ are described by Vlasceanu, Grunberg and Parlea (2007, p.63) as

“Anticipated or achieved results of programs or the accomplishment of institutional

objectives, as demonstrated by a wide range of indicators such as student knowledge,

cognitive skills, and attitudes”. Vlasceanu et al. (2007, p.63) further state that

“Outcomes are direct results of the instructional program, planned in terms of learner

growth in all areas”. The term ‘student learning outcomes’ was defined by Vlasceanu, et

54

al. (2007, p.64) as, “Statements of what a learner is expected to know, understand, and

be able to demonstrate after completion of a process of learning as well as the specific

intellectual and practical skills gained and demonstrated by the successful completion of

a unit, course, or program”.

2.9.1.1 ECSA’s View on Outcomes

Hanrahan (2007, p.51) explains from an ECSA point of view the outcomes which must

be achieved in engineering education:

The Stage 2 outcomes that demonstrate that a person has the competence to fulfil the

purpose fall into five groups as indicated below:

Knowledge-based engineering problem solving, including the analysis and

identification of problems, synthesis of solutions and the use of

fundamental, specialist and contextual knowledge;

Management of engineering activities, focussing on people, resources,

finances, processes, teamwork, leadership and communication;

Recognising and addressing the effects of engineering activities; meeting

legal and regulatory requirements; protecting the health and safety of

persons in the course of engineering activities; and conducting

engineering activities ethically;

55

Exercising sound judgement in the course of engineering activities and

being responsible for making decisions;

The ability to undertake professional development activities sufficient to

maintain and extend competence.

2.9.1.2 SAQA’s View on Outcomes

The SAQA document on National Diploma Mechanical Engineering (SAQA, Registered

Qualifications, 2010) states the following exit level outcomes:

Apply mechanical engineering principles to diagnose and solve

engineering problems;

Demonstrate mechanical engineering knowledge and skills in one or more

specialised areas;

Engage in mechanical engineering design work individually and as part of

a team;

Communicate effectively in a technological environment;

Apply management principles in an engineering environment.

The SAQA document (SAQA, Registered Qualifications, 2010) states the following under

critical level outcomes:

Identify and solve problems in which responses show that responsible

56

decisions, using critical and creative thinking, have been made;

Collect, organize, analyse and critically evaluate information;

Work effectively with others as a member of a team, group, organization

or community;

Organize and manage oneself and one’s activities responsibly and

effectively;

Communicate effectively, using visual, mathematical and/or language

skills in oral or written presentation;

Develop entrepreneurial and career opportunities;

Use science and technology effectively and critically, showing

responsibility towards the environment and health of others;

Demonstrate an understanding of the world as a set of related systems by

recognizing that problem-solving in the field of explosives does not exist in

isolation;

Participate as responsible citizens in the life of local, national and global

communities;

Be culturally sensitive across a range of social contexts.

From the above list of outcomes, the following outcomes apply to MTHE 2 and at this

level students are not required to demonstrate their ability in the remaining exit level

outcomes.

57

Exit level outcomes:

Apply mechanical engineering principles to diagnose and solve engineering

problems;

Demonstrate mechanical engineering knowledge and skills in one or more

specialised areas;

Engage in mechanical engineering design work individually and as part of a

team;

Communicate effectively in a technological environment.

Critical cross-field outcomes (SAQA, Registered Qualifications, 2010):

Identify and solve problems in which responses show that responsible decisions,

using critical and creative thinking, have been made;

Collect, organize, analyse and critically evaluate information;

Work effectively with others as a member of a team, group, organization or

community;

Organize and manage oneself and one’s activities responsibly and effectively;

Communicate effectively, using visual, mathematical and/or language skills in

oral or written presentation.

58

2.9.1.3 Exit Level Outcomes of National Diploma Mechanical Engineering

at WSU

The programs’ exit level outcomes are aimed at providing graduates with the following

attributes, skills, and competencies:

Ability to apply Mechanical Engineering principles to systematically

diagnose and solve defined Mechanical Engineering problems;

Demonstrate the application of knowledge and the requisite skills in a

Mechanical Engineering environment;

Perform procedural design of well-defined elements/components to meet

desired needs within applicable standards, codes of practice and

legislation;

Communicate technical, supervisory and general management information

effectively, both orally and in writing, using appropriate language,

structure, style and graphical support;

Acquire knowledge of self-management principles and concepts for

managing projects and/or operations within the Mechanical Engineering

environment (WSU Faculty Prospectus, 2010, pp.113-114).

2.9.2 Key Performance Indicators

‘Performance indicators’ used in higher educational institutions are defined by

59

Vlasceanu, et al. (2007, p.60) as, “A range of statistical parameters representing a

measure of the extent to which a higher education institution or a program is

performing in a certain quality dimension”. Vlasceanu et al. (2007, p.60) further explain

some examples, “… of frequently used performance indicators, covering various

institutional activities, include the number of applications per place, the entry scores of

candidates, the staff workload, the employability of graduates, research grants and

contracts, the number of articles or studies published, the staff/student ratio…”

According to Gaither, Nedwek & Neal (1994, p.1), “... the main advantage of such

performance indicator systems is their usefulness as points of reference for comparing

quality or performance against peers over time, or achievement against a desired

objective”.

A list of examples of measures being considered by the Scottish Higher Education

Institutions when developing impact and KPIs are presented by Schofield (2007, p.15):

In relation to retention: performance data collected over time on the

retention rates of students admitted through different routes and

receiving different kinds of preparatory support, thus enabling decisions to

be made about what preparation for study works best, and why;

In relation to employability: performance data collected over time on key

employability skills achieved by students on graduation, correlated with

subsequent employer satisfaction;

60

In relation to international students: performance data collected over time

on the impact of enhanced support services (including preparation for

study) for international students (by category and subject), and the

correlation with subsequent academic performance;

In relation to staff: building in questions on the impact of enhancement

activities in regular staff satisfaction surveys, thus enabling trend data to

be determined, and taking institutional action on the results.

The Australian Catholic University (ACU) summarised the purpose of their KPIs as

below:

To improve the quality of learning and teaching across all programs of the

University;

To enhance assessment and evaluation processes and outcomes;

To enhance the ACU student experience (ACU Learning and Teaching Plan

2009-2011, p.2).

In the Strategic Planning and Resourcing report of the University of Johannesburg (UJ),

KPIs are expected to measure the extent to which 10 goals (outcomes) have been

achieved. Some of the goals (outcomes) more relevant to teaching and learning are as

follows:

To promote and sustain excellence in teaching and learning by quality

61

assurance practices and actively developing and implementing innovative

teaching, learning and assessment strategies;

To establish the University of Johannesburg among the top research

universities in the country in terms of nationally and internationally

accepted research criteria;

To promote the holistic development of the student in preparation for the

world of work and responsible citizenship (UJ Strategic Planning and

Resourcing, 2007, pp.10-13).

KPI must therefore measure to what extent the desired outcomes have been achieved.

KPI can be used as a management tool to measure the institutions performance and

also on the academic side of higher education institutions, as a tool to measure the

effectiveness of teaching practices. KPIs in this research were developed based on the

selected outcomes for MTHE 2.

2.10 Summary

Social constructivism as the underpinning theory and its use in higher education was

explained. Inductive and deductive teaching and learning was discussed and their

differences were pointed out. The role that individual learning styles play in teaching

and learning approaches, were also explained. The influence of the active teaching and

learning methods, in particular EBL and GEBL on students’ development were

discussed. There was also a look at what effective teaching and learning meant and

62

how this can be achieved and measured. This was done to show the compatibility

between active teaching and learning methods and the components of effective

teaching and learning.

A description of significant learning was also given and all the components which

constitute it were addressed, together with active teaching and learning. The terms

‘deep’ and ‘surface’ learning were defined and the results and students’ aims with each

approach were explained. The importance of the movement through Kolb’s learning

cycle during a course offering to enhance student learning and to address the different

learning styles were also discussed, as well as the use of Bloom’s taxonomy for

improvement of engineering education.

SAQA and ECSA’s views on outcomes for NDME were discussed. From the SAQA listed

outcomes, those applicable to MTHE 2 were selected. The exit level outcomes listed in

WSU prospectus for NDME as well as the exit level and critical level outcomes for the

NDME as listed by SAQA were presented. The exit level outcomes listed in WSU

prospectus for NDME were presented. KPIs were formulated based on these selected

outcomes in chapter three.

The literature review has set the scene to view GEBL as an active learning approach

within the constructivist framework in general and social constructivist framework in

particular. GEBL also has all the ingredients for deep learning to occur which translates

63

into significant learning. Furthermore, the KPI’s within the context of engineering

education in general and the South African context in particular have been delineated in

this chapter.

64

CHAPTER 3

METHODOLOGY

This chapter deals with the methodology and related aspects such as the modes of

enquiry, population and sample, ethical considerations, reliability and validity, and the

methods of data analysis. The insider-outsider position to interviews will be discussed

and the selection of a specific position will be given with reasons.

3.1 Action Research

Bryman (1989, p.149) states that “Action research can reasonably be conceptualized as

a research design which entails a particular framework within which the relationship

between the researcher and the subject takes place”. In this particular study the

relationship was between the researcher as the lecturer and the students taking MTHE

2.

Reason and Bradbury (2008, p.4) define action research as:

... a participatory process concerned with developing practical knowing in the

pursuit of worthwhile human purposes. It seeks to bring together action and

65

reflection, theory and practice, in participation with others, in the pursuit of

practical solutions to issues of pressing concern to people, and more

generally the flourishing of individual persons and their communities.

Avison, Lau, Myers, and Nielsen (1999, pp.95-96) state that action research can be

categorised in four different types:

• Action research focusing on change and reflection;

• Action science trying to resolve conflicts between espoused and applied theories;

• Participatory action research emphasizing participant collaboration;

• Action learning for programmed instruction and experiential learning.

This study used the third type which was suitable to test the impact of the intervention

and to reflect on, and to take the necessary remedial action. It was also found suitable

to make changes for future teaching and learning approaches.

3.1.1 Participatory Action Research

This study was Participatory Action Research (PAR) with the researcher (change agent)

being part of this study through his academic responsibility for MTHE 2. The purpose of

this study was to develop an intervention and to implement that particular intervention.

The intervention that was chosen as a departure point was GEBL. The intervention was

then reviewed and evaluated to improve the manner in which each module of MTHE 2

66

was presented to students. The focus was to empower students, measure students’

performance not just in terms of academic scores but also in the development of

multiple skills necessary in an engineering career. The achievement of outcomes in

MTHE 2 was also measured to determine the extent to which this intervention assisted

in achieving these outcomes. Huizer (1997, p.2) states that “Participatory action

research mostly had as a purpose to find a solution to problems and conflicts”.

The aims of PAR are explained by Reason (1980, p.336) as follows:

... One aim is to produce knowledge and action directly useful to a group of

people through research, through adult-education, and through socio-political

action. The second aim is to empower people at a second and deeper level

through the process of constructing and using their own knowledge: they "see

through" the ways in which the establishment monopolizes the production and

use of knowledge for the benefit of its members.

The students were given feedback at the end of each assessment to highlight problem

areas and to make them aware of the areas in which they needed to spend more time

on. They were also encouraged to use what they have learnt from group members (e.g.

different approaches to problem solving) and to apply it during individual sessions. This

approach gave immediate feedback and allowed for sufficient time for corrective action.

67

3.2 Modes of Enquiry

This study made use of both qualitative and quantitative modes of enquiry to measure

the correlations between the quantitative data collected through assessments and

qualitative data collected with interviews. This also determined whether the data were

in support of each other and whether it was consistent. A discussion of qualitative and

quantitative modes of enquiry will be given to highlight the type of data that were

collected by means of the various instruments.

3.2.1 Qualitative mode of enquiry

According to Creswell (2003, p.179), “… qualitative enquiry employs different

knowledge claims, strategies of enquiry, and methods of data collection and analysis”.

Qualitative research involves people, their opinion, perceptions and experiences of a

particular event. There is no fixed method which can be used for all studies and

whatever the method used by one researcher may be accepted, partly accepted or

completely changed by another. To make sense of the data collected during a study

using the process of analysis may be the only thing that qualitative researchers are in

agreement with (Tesch, 1990, p.4). The 20 students who took part in this research

were interviewed individually to gather qualitative data regarding their experiences

during the intervention.

Kirk and Miller (1986, p.9) defined qualitative research as, “... a particular tradition in

68

social science that fundamentally depends on watching people in their own territory and

interacting with them in their own language, on their own terms”. Interviews were done

with the students at the end of the semester, to find out from them what their views

were regarding GEBL and how it impacted on their learning and skills development.

3.2.2 Quantitative mode of enquiry

Quantitative enquiry is in the form of numbers as opposed to qualitative enquiry which

is in the form of words (Punch, 2005, p.3). According to Burns and Grove (2004, p.21):

... Quantitative research is formal, objective, systematic process in which

numerical data are used to obtain information about the world. This research

method is used to describe variables, examine relationships among variables and

determine cause-and-effect interactions between variables.

Formative assessments, an oral test, a summative assessment and KPIs were used to

gather quantitative data from the students. These quantitative data were then analysed

to determine to what extent the intervention negatively or positively affected the

students’ performance in terms of assessment scores and to what extent the outcomes

for the course were achieved.

69

3.3 Population and Sample

The population and sample of this research study are discussed below. The process

followed to select the sample is also explained.

3.3.1 Population

The population for this study were all the students enrolled for NDME in SA. The

accessible population were 40 students who enrolled for the NDME at WSU Chiselhurst

site.

3.3.2 Sample

Marshall and Rossman (2006, p.64) state that a “... sample selection should be planned

around practical issues, such as the researcher’s comfort level, ability to fit into some

role during participant observation, and access to a range of subgroups and activities”.

The sample drawn from this population was 20 students who voluntarily agreed to take

part in this study.

3.4 Ethical Considerations

With regard to ethics in qualitative research, the research should avoid harming

participants, which includes not invading their privacy and also not deceiving them

about the research aims (Flick, 2006, p.46). The participants in this research were

70

properly informed about the purpose of the research, the methods of instructions which

they would be subjected to and the need for the voluntary participation of individuals.

With regard to ethics when performing a survey the following three important points as

suggested by Druckman (2005, p.160) were considered:

The survey should do no harm;

The information must be kept confidential;

The survey should not waste but rather respect the time of the respondents which

they set aside for someone else’s research.

All data gathered from participants for this study were treated with the strictest

confidence. WSU Mechanical Engineering classes are predominantly homogenous. The

interventions were aimed at benefiting all students.

3.5 Instrumentation

The instruments used to gather data are now discussed.

3.5.1 Instrument Construction

The instruments will be discussed in the following sequence: firstly the formative

assessments (written and oral), secondly the summative (written) assessments, thirdly

the structured questionnaire, fourthly the KPIs and a finally the open-ended interviews.

71

3.5.1.1 Formative Assessments

Three formative assessments (see Appendices 3-6) were done on six of the seven

modules in the syllabus (written tests: the duration of tests 1 and 1b were 90 minutes,

test 2 was 90 minutes and test 3 was 2 hours). These tests were designed to test the

students’ ability to interpret a problem, analyse it and develop a solution following a

certain number of steps. The students were also required to explain their understanding

of certain aspects of the syllabus and in some questions the students had to give a brief

explanation of what they understood. They also had to discuss the significance of

answers to certain questions from safety and engineering point of views. This was done

in order to determine the students’ conceptual knowledge of the course and the

application thereof. So the focus was not just on their ability to perform analytical

procedures.

Most of the questions required students to explain their understanding of what they

were to calculate before actually performing the calculation. The reason for presenting

the questions in this manner was to find out whether students actually knew what they

were doing. The aim was to teach them not just to do something without knowing the

reason or its significance. This also tested their conceptual knowledge regarding a

specific section of the work. Here the student could not obtain any mark if he/she could

not explain what was expected. These tests were allocated an ‘analysis’ score as well as

an ‘analytical’ score. The analysis scores depended on the students’ ability to recall

facts, to explain certain concepts and to give an accurate description of the processes

72

and procedures. The analysis scores were also influenced by the accuracy of

accompanying diagrams. The analytical scores were determined by the students’ ability

to analyse a problem accurately and to indicate step-by-step the process which was

followed to solve it. Structuring the questions in this way, the researcher was able to

determine whether the student understood the question and from that, whether the

student was able to identify the appropriate process or processes and then, by means

of a diagram whether the student could demonstrate what the particular process or

processes would be.

3.5.1.2 Oral Assessment

An oral test (see Appendix 7) was on the entire syllabus and the duration of each oral

test was 40 minutes. The oral test was constructed to determine the students’

understanding of certain concepts, theories and principles. They were also tested on

the functions of certain components and plants in Thermodynamics and their

application in engineering. Through the oral assessments, the understanding of

concepts by each student, his/her overall conceptual knowledge and problem areas

could be identified. The student was placed in the hot seat and could only rely on

his/her knowledge in the particular area under discussion. Although the oral tests were

very time-consuming, much was learnt from individual interaction through this method.

Joughin (2003, p.14) emphasised that literature on oral assessment is in agreement

that knowledge and understanding, applied problem solving ability, personal

competency and personal qualities can be tested with oral assessment.

73

3.5.1.3 Summative Assessment

A summative assessment (see Appendix 8) was written on the entire syllabus and the

examination duration was 3 hours. The examination followed the same structure as the

formative assessments which allowed for the testing of factual and conceptual

knowledge (analysis of questions, synthesising of data, evaluation of processes) on the

entire syllabus and the ability to perform analytical procedures.

3.5.1.4 Structured Questionnaire

A structured questionnaire (see Appendix 1) was given to the students and its duration

was 30 minutes. The questionnaire was designed to determine the students’ experience

of the GEBL approach to MTHE 2. The students could indicate what they had enjoyed

and what they found of value in terms of their learning and understanding of the

course. They also had the opportunity to indicate which aspects of the intervention they

found less helpful and where changes could be made to improve the process as well as

their rating of certain aspects of it.

3.5.1.5 Key Performance Indicators

KPIs (see Appendices 9-11) were designed to test the extent to which the outcomes

specified for this course had been achieved and to identify the poor performances in

certain areas. The course presentations in those areas were then revisited and decisions

were then made to alter the method of presentation in an attempt to make the learning

74

process more effective. This served as a gauge of how effective the teaching and

learning method of the course was.

3.5.1.6 Open-ended Interviews

Interviews (see Appendix 13) with duration of 20-30 minutes for each interview were

designed to gather qualitative data from the students’ experiences and on how they

experienced the process, what worked for them and why, and what did not work for

them and reasons for them. The interviews were also useful to find out which skills the

students acquired from the process and how they applied those skills in new situations.

3.6 Pilot Study

A pilot study which was done in 2009 with the MTHE 2 group of students to establish

the need for the study. These students were exposed to the GEBL intervention for one

semester. The GEBL intervention process was the same as the one described in this

research, however no data were recorded during this intervention to determine its

impact on students’ ability to recall factual knowledge or to demonstrate conceptual

understanding of MTHE 2 concepts, processes and procedures. Only a structured

questionnaire was given to them to find out what their opinions were regarding GEBL.

From the data collected there were positive responses regarding the need for such an

intervention where students could more actively get involved in the learning process

(e.g. group sessions) to assist them in understanding engineering courses better.

75

3.7 Instrument Reliability and Validity

This section will first describe issues around validity and reliability for quantitative data.

The trustworthiness of the qualitative data will be discussed and the measures taken to

ensure the trustworthiness.

3.7.1 Reliability

According to Carmines and Zeller (1979, p.12), “... tendency toward consistency found

in repeated measurements of the same phenomenon is referred to as reliability”. “The

reliability of an instrument is the degree to which that instrument produces the

equivalent results for repeated trials” (Bless, Higson-Smith & Kagee, 2006, p.150).

A reliability test was done of the instruments used in this study as a measure of internal

consistency. Cronbach’s Alpha is a statistical test to determine the reliability of the

instruments used in a research study (Cronbach, 1951, pp.297-334). For written

assessments the value was = 0.88 while it was 0.80 for the KPIs.

3.7.2 Trustworthiness (Qualitative Rigour)

Trustworthiness of qualitative studies refers to the extent to which the credibility,

transferability, dependability and confirmability of the research can be ensured (Lincoln

& Guba, 1985, p.301). Activities increasing the probability that credible finding will be

produced are prolonged engagement, persistent observation and triangulation (Lincoln

76

& Guba, 1985, p.301). In so far as addressing the credibility of this study, the

researcher was personally involved with the sample twice a week for 120 minute over a

period of 13 weeks. During these contact sessions constant observations and

interactions took place to guide and assist the groups during problem solving sessions

on each module of the syllabus. The quantitative assessments were all supported with

detailed memoranda, indicating the mark allocation clearly which would ensure

consistency with regard to scores. Quantitative and qualitative data were compared to

look for similarities and differences to ensure a high degree of credibility.

According to Ary et al. (2008, p.501), in addressing the transferability, “The researcher

must strive to provide accurate, detailed, and complete descriptions of the context and

participants to assist the reader in determining transferability”. The sample from the

accessible population was 20 students registered for NMDE MTHE 2 at WSU,

Chiselhurst. In section 3.9 of this chapter the researcher gave a detailed description of

how the intervention was carried out and how the researcher was involved in the study.

Dependability was addressed by the construction of an interview schedule with clear

statements as well as follow-up statements/questions done by a person who served as

an insider-outsider (this is explained in section 3.8). Participants were given the

opportunity to withdraw at any time and were taking part purely out of their own free

will. Data transcriptions were also made available to participants to check the accuracy

of what they have said. To address confirmability an in-depth methodological

description of the research process and data collection procedure were given.

77

Confirmability can be achieved by “... in-depth methodological description to allow

integrity of research results to be scrutinised” (Shenton, 2004, p.73).

3.7.3 Validity

With reference to validity, Carmines and Zeller (1979, p.17) state that “... validity, then,

is evidenced by the degree that a particular indicator measures what it is supposed to

measure rather than reflecting some other phenomenon”. On the issue of validity Cano

(2000, p.4) states that it, “... measures what you said you would be measuring or

explaining. It therefore deals with the appropriateness of the method to the research

question”. Ary, Jacobs, Razavieh and Sorensen (2008, p.225) explain that “... validity

was defined as the extent to which an instrument measured what it claimed to

measure”.

The researcher has taken the necessary steps with the development of the instruments

to ensure their validity. Assessment criteria and mark allocations were clearly indicated

to ensure that the instruments measured what they claimed to.

There are also other terms associated with validity such as content or face validity,

internal validity and construct validity. As stated by Mohammadi (2008, p.343),

“Content validity, also called 'face validity', has to do with items seeming to measure

what they claim to”. Instruments were designed to collect data on the entire MTHE 2

syllabus.

78

According to Merriam (1995, p.53), “Internal validity asks the question: how congruent

are one’s finding with reality?” Roe and Just (2009, p.3) define internal validity, “... as

the ability of a researcher to argue that observed correlations are causal”. The sample

for the purpose of this study constituted students whom voluntarily agreed to take part.

The sample also represented 50% of the accessible population. This research was

action research with only one group of students undergoing GEBL.

According to Thiѐtart (2001, p.198) construct validity is a measure of, “... whether the

variables used to measure the phenomenon being studied are a good representation of

it”. Detailed memorandums with mark allocations were developed for each formative

and summative assessment. The questionnaire had a Likert-type scale with five

different ratings.

Before the questionnaire was handed out to the students it was given to a professor in

the field who analysed its suitability in terms of the research questions. Feedback from

the professor was positive in terms of the suitability of the questionnaire and for

ensuring its validity.

3.7.4 Triangulation

Triangulation was made use of used integrate and corroborate the qualitative data from

the interviews and the quantitative data from the questionnaires and assessments.

“Triangulation can, under certain assumptions, be argued to unite research

79

contributions in such a way as to transcend the use of specific methods in a disciplinary

sense” (Downward & Mearman, 2006, p.2). Both the formative and summative

assessments were used during the triangulation process. “... it is important for

engineering education classroom researchers to consider other sources for

triangulation, such as scores on specific assignments or test questions, concept

inventories or focus groups that complement the principal measurement procedure, and

retention or passing rates in subsequent courses” (Borrego, Douglas & Amelink, 2009,

p.62).

3.8 Insider Outsider Position to Interviews

To avoid the research bias, the insider/outsider position for interviewing the students

was decided upon. If interviews were conducted by the researcher (MTHE 2 lecturer)

there would have been an authority disposition. This could have led to students giving

answers out of fear of being judged. During the semester, a certain relationship

developed between the researcher and the students which might have affected their

responses. They might have felt that the researcher wanted to hear certain favourable

answers (whether true or false), or that the researcher would have liked to hear

positive responses with regard to the intervention, which might have led to specific

questions and follow-up questions being formulated to achieve this goal.

The insider position – a disadvantage of the research being conducted by someone who

qualifies as an insider is that he/she does not maintain enough distance and objectivity

80

necessary for research validity (Brannick & Coghlan, 2007, p.60). An advantage when

conducting interviews is that the, “... insider status may enhance the quality and

effectiveness of qualitative interviews” (Hodkinson, 2005, p.138). This however did not

apply in this context, because the interviewer was not part of the research and

therefore had no reason not to be objective in his/her behaviour.

The interviews were conducted by a part time laboratory assistant (former student)

who was busy with his B.Tech in Mechanical Engineering but had already passed

Thermodynamics 4. The interviewer was therefore well equipped in terms of

understanding MTHE 2 content. This also created a more relaxed atmosphere for the

students being interviewed by a former student and someone from the same ethnic

group. In this context the interviewer was an insider and this relationship allowed the

interviewees to behave naturally and relaxed and highly disposed to give honest

responses. Another contribution to the insider stance was that there was also no major

difference in authority.

The outsider position – allowed for interviews to be conducted without preconceptions

or any vested interest (Ritchie, Zwi, Blignault, Bunde-Birouste & Silove, 2009, p.108).

According to Tinker and Armstrong (2008, p.58), “... outsider status could potentially

limit a researcher’s understanding of the material but it can also improve data analysis

by allowing him or her to maintain a sense of critical distance from the topic of

investigation”. Training was therefore done to prepare the interviewer for conducting

81

interviews and how to pose follow-up questions. Not being part of the MTHE2 group

who underwent the intervention allowed the interviewer to ask questions without

predicting what the responses could be. The interviewer’s interpretation of the

responses was from a neutral position and follow-up questions were guided by the type

of response from a particular question. In this context the interviewer was an outsider.

This finally resulted in interviews being conducted by someone who qualified as an

insider as well as an outsider giving more validity to the data collected.

3.9 Intervention Process

A detailed explanation of the intervention process is given below:

Lecturing was done on the first module, to introduce basic concepts and to explain the

outcomes at the end of the module to the students. An example was done by the

lecturer by writing the information given in the problem on the board and then solving

it the way he understood it and with the method most obvious to him. Most students

were completely lost during this exercise. The students were then given a problem/s to

solve on their own and the lecturer was available to assist those experiencing difficulty.

The first formative assessment (see Appendices 3 & 4) was done on module one and

the results were analysed. KPIs (see Appendices 9-11) were developed to measure the

achievement of the course outcomes on the first module (these KPIs are discussed

later). Lecturing was done on the rest of the modules with GEBL being used in problem

solving exercises. An introduction to the new course material was done to ensure that

82

the students could connect with what was about to be discussed. The introduction

normally took between 30-45 minutes of the 120 minute session. This enabled the

students to follow the explanations and discussions without being lost. By laying this

foundation, the students could then build further on it by reading reference material,

and discussing it with peers. The students were also given a booklet (see Appendix 12)

with an enquiry-based learning worked-out example on each module of the syllabus. In

this example, a problem was given and certain unknowns had to be calculated. The

procedure was then to analyse the problem by asking questions on and about the

problem. Answers to these questions would then make the process more

understandable or would lead to other questions. Following-up on all the new questions

would eventually give answers to all the unknown information in the problem. This

would result in the student understanding the problem, as well as what is required to

be determined and the steps to follow to find a solution. The GEBL flow process is

presented below:

83

Figure 3.1: GEBL intervention flow process

The purpose of the worked-out examples was not only to demonstrate the enquiry-

based approach of problem solving to the students, but also for each student who

worked through these examples to learn more about a specific topic and to show and

assist him/her to develop the ability to pose well-formulated questions and follow-up

1. Lecturer introduced basic

concepts, principles and

theories in MTHE 2

Students listened and took

notes

3. Lecturer presented groups with a

new problem to solve using GEBL

approach

Students were given a few minutes

to formulate three to five most

relevant questions in their groups

2. Lecturer did an example with the

class applying GEBL principles

Students took part in formulating

questions to analyse the problem

5. Students worked in groups and

analysed the problem with

questions and follow-up questions

Lecturer acted as a facilitator and

moved between the groups to give

assistance

4. Lecturer received feedback

from all the groups on the

questions they had formulated

and gave assistance to those

groups with difficulties

6. Lecturer compared different

approaches to a solution and

rectified misunderstandings

84

questions. These questions were goal directed and were formulated to take the student

through the analysis process as fast and effectively as possible.

A second formative assessment was done (see Appendix 5). The results were analysed

and problem areas were identified. Corrective action was taken to address these

problems. Because these modules were so vastly different, each module required a

unique approach in terms of question selection. Continuous assistance had to be given

to the students in their attempt to identify, select and formulate questions for problems

in each of the modules. KPIs were used again to measure the extent to which the

outcomes had been achieved. A third formative assessment was done (see Appendix 6).

The results were analysed and problem areas were identified. Corrective action was

taken to address these problems. KPIs were used to test the achievement of the

outcomes. Finally an oral assessment (see Appendix 7) was done on the entire syllabus.

The purposes of the oral assessment were to hear from the students on their

understanding and explanations of various MTHE 2 processes and procedures, to find

out whether they actually knew what they were doing when they performed certain

calculations and what the engineering significance of the item/factor was. This detail

was not always clear from written assessments. KPIs formulated to test the

achievement of certain abilities as required by the various outcomes were applied to the

oral tests performances. A summative assessment (see Appendix 8) was written on the

entire syllabus. KPIs were used to determine the overall achievement of the course

outcomes with the final examination. At the end of the course, a structured

85

questionnaire (see Appendix 1) was handed-out to gather quantitative data from group.

3.10 KPIs for this Study

Based on the outcomes and KPIs referred to in chapter two, the following KPIs were

formulated by the researcher based on the selected outcomes listed below:

1. Students’ ability to apply MTHE 2 principles to analyse and solve problems

accurately:

KPI ‘1’ measured the extent to which the student could recall information (facts,

theories, formulas), the student’s skill to analyse a problem and develop a solution

using his/her subject (factual and conceptual) knowledge.

2. Students’ ability to explain/discuss the operation of a system, components or

parts of a Thermodynamics system, component function in the overall plant

which it forms part of and treatment and maintenance procedures of specific

components:

KPI ‘2’ measured the extent to which the student understood the course content

(conceptual knowledge), how Thermodynamic systems operated, what the function of

each component in a plant was, which factors affected the plant operation, how and

why treatment is done and what the result would have been if the treatment was not

86

done effectively.

3. Students’ ability to perform technical discussions on MTHE 2 topics, to

communicate fluently and explain and demonstrate concepts effectively in MTHE

2:

KPI ‘3’ measured the extent to which can the student carried out discussions on course

related topics, the extent to which the student communicated fluently with his/her

peers and whether a student could do a demonstration or perform and explain a

specific concept or theory.

4. Students’ ability to analyse a complex problem and produce a solution, taking

into account crucial factors in a systematic approach towards the solution:

KPI ‘4’ measured the extent to which the student could analyse complex problems

where certain factors were crucial and without which an optimum solution could not be

achieved. Here, the student also needed to demonstrate his/her ability to develop the

solution systematically.

The three formative assessments and the final summative assessment were designed to

test the student’s ability to analyse a problem, explain the information given and what

needed to be determined, reflect the process on a detailed diagram and to decide on an

87

approach to find the solution. KPI numbers ‘1’ and ‘4’ were used to measure the extent

to which the outcomes for these activities had been achieved. The final oral test was

designed to test the student’s ability to interpret a question, explain his/her

understanding of the problem; explain how systems, components and engineering

processes function and their purposes; and discuss the effects and influences on output

and performance when certain variables were altered. KPI numbers ‘2’ and ‘3’ were

used to measure the extent to which the outcomes for these activities were met.

The KPIs used a scale of 1 to 5 with full and half mark allocation as indicated in

Appendices 9-11. It is also important that the reader examines these KPIs in

conjunction with relevant outcomes for clarity and relevance.

3.11 Procedures

For the quantitative data collection assessment, duration varied from 30 minutes for the

structured questionnaire to 3 hours for the summative assessment. For qualitative data

the interviews took approximately 30 minute per interview. KPIs were then used to

evaluate the scores for each category (theoretical: content knowledge, explanation

understanding and discussions; and analytical: knowledge to recall formulas, substitute

values and calculate answers) to determine the overall achievement of the course

outcomes. The structured questionnaire made use of a Likert-type scale with five

different ratings. The total student responses per rating were then determined and

expressed as a percentage of the total number of students. The students’ score in the

88

formative and summative assessments were also expressed as a percentage of the total

for that particular component (i.e. ability to analyse, ability to analytically solve and

overall). The students’ interview responses were then compared to the quantitative

scores to determine whether what has been stated by the student actually occurred.

Individual as well as overall comparisons were made.

3.12 Data Analysis and Interpretation

Data were collected over a period of six months from the research sample as follows:

Formative assessments (three written tests) – quantitative data

Oral test on entire syllabus – quantitative data

Summative assessment (written examination) – quantitative data

KPIs – quantitative data

Questionnaires – quantitative data

Interviews – qualitative data

Predictive Analysis Software (PASW) programme was used to evaluate the quantitative

data collected during this research and N-Vivo was used for the qualitative data. A

statistician was also consulted for assistance in the accurate interpretation of data.

The data were analysed to find out to what extent the research questions had been

answered. This analysis also provided information which was used to test reliability and

89

validity of this study.

3.13 Summary

Action research created the scenario for the researcher to get involved with the

intervention process and to be part of the development process, constantly giving

assistance and support during the group sessions but also allowing the students’ to

drive their own learning processes. This design allowed for rigorous testing of students’

conceptual understanding and problems solving abilities. The instruments for this study

were the semester tests and final examination with the addition of an oral test,

structured questionnaire, KPIs and interviews. KPIs based on the outcomes for MTHE 2

were formulated. All data gathered from these instruments were quantitative and only

the data collected from the interviews were qualitative. Both types of data were used to

ensure reliability of the study.

90

CHAPTER 4

DATA ANALYSIS AND INTERPRETATION

This chapter presents the analysed data and the interpretation thereof. The

demographics of the study will first be presented, then the qualitative data, followed by

quantitative data on formative and summative assessments, quantitative data from KPIs

and finally a summary of the data presented.

4.1 Demographics of the Study

The sample (n = 20) consisted of:

Frequency Gender Age

1 Female 18

1 Male 19

5 Male 20

1 Female 20

3 Female 21

2 Male 21

3 Male 22

1 Female 22

1 Male 23

1 Female 24

1 Male 26

Table 4.1: Demographic data

The sample comprised 13 males and seven females. While 19 were Xhosa speaking one

was English speaking. Students’ age ranged between 18 and 26 years (M = 21.1 years,

SD = 1.78)

91

4.2 Qualitative Data Analysis, Interpretation and Discussion

This section focuses on the qualitative data gathered during the interviews (see

Appendices 2 & 13). These interviews were done with students to find out more about

what they had learnt during the intervention and to determine what they found useful

in GEBL and whether it did assist them in their learning.

From the Interview Questions:

Students’ responses (see Appendix 13) are included (verbatim) to indicate to the reader

what their opinion and experience was with regard to GEBL and their responses to the

interview questions (see Appendix 2).

The interview questions were categorised under the following headings with emerging

themes listed under each:

Group sessions

Enquiry Based Learning (EBL)

Communication

Active learning

Notes

Problem analysis

Understanding

92

Teaching atmosphere

4.2.1 Addressing the First and Second Research Question

With reference to the first and second research questions ‘What would be the effect of

a guided enquiry-based learning (GEBL) approach on mechanical engineering students’

factual recall of MTHE 2 concepts?’ and ‘What would be the effect of a guided enquiry-

based learning (GEBL) approach on mechanical engineering students’ conceptual

understanding of MTHE 2 concepts, principles and applications?’, the following themes

emerged and the students’ responses are given under each theme beginning with the

researcher’s summary which is followed by quotes from selected students to illustrate at

least one example of response.

The following themes emerged from the heading, ‘group sessions’ and ‘active learning’:

4.2.1.1 Group sessions helped understanding of other courses

Many students found the group sessions helpful and effective in learning new work to

such an extent that they then adopted the same approach in other courses too. During

group sessions, students exchanged views and discussions took place at a level that

most students could understand and follow. Understanding the work enabled them to

solve problems in groups and also on their own. The gap between students’ reference

frameworks is much smaller than between the lecturer’s reference framework and that

of the students. The gap between students’ and lecturers’ reference frameworks can

93

lead to departure points of new work being introduced to the students that may be

above their level of understanding and as a result students can get lost from the word

go. In this regard, student A’s sentiments epitomize the students’ views when he said:

“Yo! Very much so! Hence I am saying that even in the other courses I am also

using it and it is really working for me. Last semester I did the same approach

and it is still working, you see”.

4.2.1.2 Group sessions encouraged preparation and participation

Once a section of work was covered in class, the students were given homework to do

to prepare for the following lecture. Most students indicated that they did their

homework so that they could participate and explain to their peers how they had

tackled a specific problem. They also stated that if they came unprepared they would

be left behind by the others.

GEBL differs from the traditional approach in the sense that more is expected from the

students attending classes. During the group sessions students had to deliver, produce

evidence of what they did, how they approached certain questions or how and why

their approach differed from those of others. Students indicated that with other

courses, not much was really expected from them from one session to another. So

whether did his/her homework and prepared for the next class was entirely up to the

94

student-nothing was there to encourage them other than just the normal talk and

chalk. In this regard, student B’s sentiments epitomize the students’ views when he

said:

“Because I know that I have to work at home, I have to do problems then I can

explain when with the groupmates, so I have to explain what I understand and

they will gain something from me”.

In this regard, student C’s sentiments epitomize the students’ views when he said:

“Unlike the method that we are using in other courses, you can’t actually go to

the class if you didn’t prepare because there is nothing much expected from you,

all you do is just staying in the class and listening to the lecturer”.

In this regard, student D’s sentiments epitomize the students’ views when he said:

“... so I have to come prepared so that I can’t be left behind so that I can work

together’.

The fact that they actually understood the work inspired students to work harder and to

learn more about the course – this gave them a sense of belonging and motivated them

to do more than just taking notes which was normally the case in other courses. In this

95

regard, student E’s sentiments epitomize the students’ views when she said:

“Ja it actually involves you as a student, you know you want to do this thing

cause you understand it and you want to learn now. It gives you that positive

drive – now I want to study I want to learn not just sit in the classroom and

taking notes...”

Active participation is the main reason for the group sessions. This forced the students

to concentrate and apply their minds to what was being discussed. Sitting in a class did

not necessarily mean that the student was concentrating on what is being presented by

the lecturer. Being part of a discussion, they had to concentrate, which made these

sessions much more effective. In this regard, student I’s sentiments epitomize the

students’ views when she said:

“... because group working is all about all the students participating...”


“... because you’re going to be in group sessions and you’re going to have to

discuss and not just listening to your group members”.

96

4.2.1.3 Group sessions allowed for explanations in mother tongue

Students who were not fluent in English also had the opportunity to explain and

participate in their mother tongue during the group sessions. These students were

therefore not excluded from the discussions which would have been the case in the

traditional teaching method where most of the time a discussion would take place

between the lecturer and the entire class. In this regard, student A’s sentiments

epitomize the students’ views when he said:

“So now as we were working in groups, it was well effective such that we were

well able to explain everything and maybe in Xhosa now to explain to one

another how this is, how the processes are going and then it was well

understood...”

4.2.1.4 Individual problem areas

When students did their preparation for the lecture that followed the previous one, they

would pick up the part of the work with which they struggled. During the session that

followed they asked for assistance from their peers or the lecturer. These problem

areas were then addressed and rectified upon and those students were not left behind

as the course progressed. In traditional teaching, students did not have this opportunity

and in many instances were left behind and eventually dropped out of the course. In

97

this regard, student C’s sentiments epitomize the students’ views when he said:

“Yes of course, because if you didn’t come to the session prepared, you wouldn’t

really know which area you need help on and which one you’re fine in...”

4.2.1.5 Students used group session experience

When students did their homework they used their group session experience and

approaches to solve new problems. The questions that they asked, served as a ‘guide’

on how to analyse problems. There was no fixed rule, but they had to systematically

work through a set of questions which they had formulated in order for them to

understand the process/processes in the problem, what information is supplied with and

how they could use that information in developing a solution to the problem. In this

regard, student C’s sentiments epitomize the students’ views when he said:

“Ja it helped me a lot because in group sessions before we actually tackle the

problem we would have a list of certain questions that we ask to ourselves.

Questions like what information is given and how do I use information, what’s

the problem, where do I start in solving the problem. Those questions helped us

a lot in groups and we would use those questions even when you’re alone, the

same method we used in the group”.

98

The following themes emerged from the heading ‘understanding’:

4.2.1.6 EBL encouraged understanding

Students said that they had developed the skills to read a problem and then interpret

and analyse it correctly. The fact that they discussed and listened to each others’ views

made them aware of different approaches to the same problem and that the problem

could be approached from different angles. This interaction resulted in the development

of their ability to read a problem and ask questions like: what is given? What must be

determined? What the process or processes are involved? The answers to these and

other questions were then developed in order to systematically find a solution to the

problem.

In contrast with the norm, students found it easier to actually understand certain

theories, principles and concepts. They said that GEBL assisted them in understanding

the work better than before which then also helped them in their discussions and

analysis tasks. Students stated that they really understood the work this time to such

an extent that they could explain it to others. In this regard, student C’s sentiments


99

“... when you understand the subject it becomes easy to pass it... this method

gives us that ability to understand it and not just guessing or memorizing it, but

to actually understand it”.

In this regard, student A’s sentiments epitomize the students’ views when he said:

“So now that way of, the traditional way of teaching it is just them giving us

information and you just don’t understand, you’re just completely lost...”

4.2.1.7 Traditional method allowed for little peer support

Students indicated that with the other courses (traditional teaching method) there was

no opportunity for group interaction and that these interactions actually assisted them

in understanding new work by sharing ideas and explaining to one another. In this

regard, student F’s sentiments epitomize the students’ views when he said:

“... if it can be introduced in other courses, because you will find that in other

courses the lecturer stand in front of the class, he teaches and then he goes

out...”

100

4.2.1.8 EBL developed the ability to manipulate information to solve

problems

Responses from students indicated that they were now in a position to manipulate

information supplied in questions. They were also able to look at different approaches

to solve problems, because they actually understood the work they were dealing with.

It was no more a case of using any formula that came to mind, but using the

information supplied and their understanding of the problem (process/processes) to

develop a specific approach for a solution to the problem. In this regard, student A’s

sentiments epitomize the students’ views when he said:

“Now I am in a position of even if they change the question around I will be well

able to use my own information you see I am in a position to analyse the

question and getting to manipulate whatever it is that I have”.

The following themes emerged from the heading ‘enquiry-based learning’:

4.2.1.9 EBL linked theory and practice

Students expressed their satisfaction with the EBL method. EBL did not just assist them

in understanding course content but it also helped them to put the theory taught in

class in perspective with its application and the relevance in industry. Being able to link

101

what has been taught in class to a practical application made understanding of certain

concepts or processes also easier and more effective than was the case in the past. In

this regard, student A’s sentiments epitomize the students’ views when he said:

“... not just knowing what you calculate but what is it in the engineering field

what significance does it have...”

Student’s expressed their opinion on the atmosphere created by GEBL as compared to

the traditional teaching and learning method. In this regard, student A’s sentiments


“... the teachers as well, they should also create that atmosphere for us to be

free to ask questions, because at times it can be very tense in class...”

In this regard, student H’s sentiments epitomize the students’ views when she said:

“... sometimes I find that I don’t understand and I don’t want to ask the lecturer

can you please explain to me but if I ask in my group session and the lecturer

comes to the group session and then I ask him privately because I am a shy

person”.

102

4.2.1.10 EBL was a more effective way of learning

Responses from the interview questions indicated that students found EBL more

effective and that according to them they learned more with this method than the

traditional one. At the end of a session they understood the work better than from the

traditional approach and could analyse and solve problems more effectively than in

other courses. In this regard, student A’s sentiments epitomize the students’ views

when he said:

“Yes, all I can say it is a fact that this has really been very, very effective for me

and I believe even for the other rest of the students that we are telling”.

4.2.1.11 EBL required active engagement

During group sessions every student got the opportunity to express themselves and to

share their views. This resulted in all students being actively engaged in the learning

process during these sessions. Lecturing time was reduced to allow for more time to be

spent on problem solving. This resulted in students being passive for a fraction of the

time when the lecturer was introducing a new concept. Once again students indicated

that active involvement improved learning and understanding. In this regard, student

I’s sentiments epitomize the students’ views when she said:

103


The following themes emerged from the heading ‘notes’:

4.2.1.12 Search for information

In the notes there were additional questions on each section of the syllabus. This

guided the students through a process of reading the questions and studying the

answers. Being stimulated by these questions students engaged themselves in a

research process to find out more about the topic under discussion – eventually this

leads to an expansion of the overall knowledge on the topic. In this regard, student J’s


“In the booklet we are given extra questions to be asked at the end of each

module, so basically those questions kind of push you in researching more of the

module itself”.

4.2.1.13 Notes contained relevant information which assisted in

understanding

According to the students the manner in which the course material was presented in

the booklet (questions on theory, principles and procedures) made the content easier

for them to understand. They stated that the booklet explained the course material in

104

such a way that they could actually follow and understand it. Students also mentioned

that some of the text books were written in advanced English and that they found it

difficult to follow discussions. Being able to follow the course and understanding what

they are doing made them feel good about themselves and gave them a more positive

feeling towards MTHE 2. In this regard, student J’s sentiments epitomize the students’

views when he said:

“... the questions in the booklet also were very relevant to the main question

asked to understand the work not just to memorise the formulas”.


“First of all they help you to understand the topic that you are dealing with, it

gets you to understand it much better, it elaborates everything you see. It is like

it enhances your knowledge and it makes you understand problems much

easier... Yes, it just gets you to understand that particular subject much easier –

like it just expands everything to you - you get to know everything...”

4.2.1.14 Notes had questions to assist in understanding problems and

theory

When a new section was introduced, the students had to work through the example as

well as the additional questions in the notes to gain a better understanding of the work.

105

The worked out examples in the notes showed the students how to go about analysing

a problem, how to find out what information was given and how this information could

be used to find a solution to the problem. There was a list of questions in the notes

which the students could use or alter to suit their particular situation. Working with

these questions also developed the students’ skills to formulate relevant and

appropriate questions to address specific issues. These questions were then used to

analyse problems and to get to understand problems before attempts were made to

solve them. In this regard, student K’s sentiments epitomize the students’ views when

he said:

“It shows how to approach a problem and then it gives you a certain question

that you must ask in order to understand and approaching the question”.

In this regard, student F’s sentiments epitomize the students’ views when he said:

“Yes this booklet we have with questions and answers you read through the

theory and you read the questions and answers so that at the end of the day you

end up being aware of what you are being taught in class, what is it that the

lecturer told us about not just calculate, calculate, calculate as we are used to

doing in other subjects”.

106

In this regard, student I’s sentiments epitomize the students’ views when she said:

“... this booklet with additional questions helped me because it helped me to

analyse the questions very easily because of the explanation it had”.


“First of all they help you to understand the topic that you are dealing with, it

gets you to understand it much better, it elaborates everything you see”.

4.2.1.15 Notes guided students in question formulation

The workout examples in the booklet helped the students to learn how to approach a

problem with enquiry based method. Then they applied this systematic approach when

they did the exercise questions and that helped them in their analysis and

understanding of new problems. In this regard, student L’s sentiments epitomize the

students’ views when he said:

“Yes they helped me because if you are solving a problem I learned a skill that

you should ask questions, based on that question so that you can get each and

every information that you were given...”

107

In this regard, student J’s sentiments epitomize the students’ views when he said:

“... it makes it easy and work, we had a textbook which had questions and how

to draw the diagrams and how to ask questions and what you should consider

doing first...”

4.2.1.16 Notes stimulated interest

The GEBL notes were aimed at making a connection between theory and practice to

improve understanding. The examples were presented in such a manner that the

students could understand the practical relevance and importance of what was being

taught. This also stimulated student interest which resulted in students’ spending more

time on that which they found interesting and enjoyed. In this regard, student F’s


“In that book, that the lecturer gave us, they offer explanation of even about

boilers, I want to learn about boilers, then I got interested to work with boilers

when I finish my course, even now he gave us a project to do about boilers”.

108

The following themes emerged from the heading ‘problem analysis’:

4.2.1.17 Sequences to problem solving

When the students were given new problems to solve, the process was that they had to

write down individually some question which they felt could help them in analysing the

problem. These questions were then discussed in the group and later in the class in

general to compare the similarity of questions formulated between the groups. This was

basically the approach during all the sessions and that gave the students a certain

departure point when they faced a new problem. They then worked systematically

through the questions and once all the questions were answered they would be in a

position to develop the solution to the problem. In this regard, student C’s sentiments


“We were encouraged to write down a certain sequence of each question and

how to answer the question and we were given time before each problem to

evaluate how we were going to actually answer the question, not just looking at

the question and trying to answer that specific question, cause you have to find

a number of things before you answer the actual question that’s asked... before

we actually tackle the problem we would have a list of certain questions that we

ask to ourselves”.

109


“... to know which step you should move to and how you should approach the

question. In a way it gives us a start in approaching the questions...”

4.2.1.18 Students used certain sequences when working individually

At the end of the module, students had to become capable of solving problems without

relying on their peers. This approach to problem solving where they had to pose a

number of questions to which they had to find answers were then also used very

effectively by individual students when they did their home work. In this regard,

student E’s sentiments epitomize the students’ views when she said:

“... when you are at your own, doing homework or something you know how to

tackle a question, how to start from the beginning – you know how to solve

problems step by step...”


“... when we solve problems as a group session, there’s a rule then, and then

when I solve the problem on my own I use the same thing...”

110

4.2.1.19 Peers’ problem solving approaches

Sharing problem solving approaches with peers in the group made students aware that

there could be more than one approach to solving a problem and that they should

always bear in mind possibilities of different approaches. Being aware that a problem

could be analysed and solved from different angles enabled students to consider the

given information in the problem first, before they started to plan a specific approach.

In this regard, student K’s sentiments epitomize the students’ views when he said:

“I enjoyed working with other students and to see how other students are

approaching the sum... you learn a lot of skills in approaching the sum because

you are dealing with different people with different styles of approaching the

sum...”

In this regard, student I’s sentiments epitomize the students’ views when she said:

“... in groups you know you get more information because all of us we come up

with different types of information...”

111

The following themes emerged from the heading ‘understanding’:

4.2.1.20 Explored alternative problem solving approaches when

understanding

Students stated that they have realised if they understood a section of the work

properly and they had to solve a problem under that particular section, they could use

their knowledge to consider different methods of solving the problem. Manipulating

given information and formulas gave them the freedom to solve problems in more than

one way. In this regard, student K’s sentiments epitomize the students’ views when he

said:

“... so if you do understand you know how to approach a problem in other

ways... so you have the ability to analyse the question and explore others ways

how to approach this problem”.

4.2.2 Addressing the Third Research Question

In addressing the third research question ‘What would be the effect of a guided

enquiry-based learning (GEBL) approach on mechanical engineering students’ ability to

communicate procedures and processes related to MTHE 2?’ the following themes

emerged from the heading ‘communication’:

112

4.2.2.1 Group sessions assisted communication with strangers

During discussions in their groups students were given the opportunity to speak in

English, expressing their views and understandings. They also had to listen to their

peers’ explanations and understandings. This was an opportunity to improve their

English proficiency as they were part of the discussion and they were exposed to how

others expressed themselves as well as new terms and new words that were used.

During group sessions the students were rotated which also exposed the students to an

exercise where they had to communicate with strangers. In this regard, student C’s


“In the group we had to first raise your suggestion in approaching the problem...

first had to like explain how do you understand the problem and you can

establish where you can start in trying to solve the problem and we would do

that in talking, so that helps us then in communication skills”.

4.2.2.2 Peers could explain to one another

Students had their own ideas when it came to problem solving and these ideas they

shared with each other. In the case of different approaches or interpretations to a

problem they debated their differences and had to convince their peers that their

approach is the correct one based on facts. This placed further pressure on the

113

students to come prepared to class and to have their facts ready during these

discussions. These discussions could not be convincing if students only memorised the

work, but they really had to understand it to be able to present a convincing argument.


“Everyone in the group would come with their own ideas... You know in

discussions you would go through in groups, debates and we are challenging

each other in the groups someone gets to be disagreeing with you in the group

and you will have to try to convince and explain to him exactly how you really

view this...”

In this regard, student N’s sentiments epitomize the students’ views when she said:

“... we communicate about the question and if someone does not understand the

question you explain so that he/she can understand the question”.

4.2.2.3 EBL developed multiple skills

Students indicated that they not only learned content but were also developed in other

areas. They were encouraged to participate in group discussions with strangers which in

turn gave them confidence to express themselves in front of other people. This is an

important skill in the engineering field and if the students’ communication skills can be

114

developed to its full potential it will only be to their benefit. In this regard, student L’s


“I think in this method you gain a lot of skill other than solving the problem, first

you get a chance to communicate and be motivated to be not shy in class

because you have to solve problems with other people in the class... I think this

method we used in Thermodynamics is better, because you don’t just gain a

chance to solve the problem, but you can gain other skills other than solving

problems like talking in front of the people because in Thermo you have to share

the information with the group members”.

4.2.2.4 Thermodynamic terms

With regard to communication, students indicated that when participating in group

discussions they learned to use Thermodynamic terms which resulted in them becoming

more familiar with these terms which in turn helped them in understanding the course

content and problems better and this they would not have done when working alone.

Talking about various Thermodynamic aspects in group discussions, they had to say out

the terms loud, and this helped them in improving their pronunciation of these terms. It

also gave them more confidence in discussing Thermodynamic related concepts,

because now they were able to use the terminology correctly. In this regard, student

M’s sentiments epitomize the students’ views when he said:

115

“In Thermodynamics there are a number of terms and well just terms you need

to know that you don’t really pick up if you do work without talking about the

work. So the fact that you were talking about the work helped you to understand

these terms and in turn helped you understand more Thermodynamics”.

4.2.2.5 Explained problems to peers

When students explained problems to their peers and communicated in the group

sessions, they felt that communication skills improved and their language proficiency

actually improved. They indicated that they learned new words and that their ability to

express themselves improved. This would not have been the case with the traditional

teaching method. In this regard, student K’s sentiments epitomize the students’ views

when he said:

“It helped develop our communication skills because you get to speak out,

explaining what is happening about the sum...”

4.2.2.6 Shared views with others

Communicating with their class mates during the problem solving sessions, created the

opportunity to share their views which helped them in their understanding and

strategies to analyse and solve problems. These group sessions developed multiple

skills of students i.e. problem solving skills, communications skills and confidence to

116

express themselves in front of strangers. In this regard, student K’s sentiments


“... you can share your views with other people...”

In this regard, student F’s sentiments epitomize the students’ views when he said:

“When you are working in a group you gain something and you give something

to the others, you get some ideas how to tackle the problem...”

4.2.2.7 Group sessions improved communication

For all students except one, English was not the mother tongue. All these students

indicated that taking part in group session discussions helped them develop their

communication skills. They felt more confident in expressing themselves in technical

discussions. In an engineering occupation one must be able to communicate fluently,

be able to express oneself in technical areas, and be able to explain and demonstrate

certain processes effectively. In this regard, student B’s sentiments epitomize the

students’ views when he said:

117

“Because I have to talk to others and they must talk to me too. When doing this

on my own I don’t communicate with someone so when I am with them I can

communicate”.


“Because as we share that information, so when we speak we know how to

speak with another and it helped me a lot because now I know that I can explain

that to another person and then we can share”.

The following themes emerged from the heading ‘teaching atmosphere’:

4.2.2.8 Group sessions allowed students to speak freely

In the traditional teaching method, the lecturer posed a question to the class or to an

individual who would simply respond ‘I don’t know.’ This made it difficult for the

lecturer to determine whether the student understood the work but was just shy or

whether he/she really did not understand the work. With the group sessions they could

speak freely to their peers and ask questions if they did not understand something.

Those with more confidence would then call the lecturer for further help if needed. In

this regard, student J’s sentiments epitomize the students’ views when he said:

118

“Yes, discussing in the groups – firstly it is not like answering your lecturer so

basically you can speak freely confidently...”


“I think the lecturer was able to make the environment free. He made the

environment so free that you were so more able to ask questions anyhow and at

anytime...”

4.2.2.9 Feeling relaxed during problem solving

Comparing the classroom atmosphere between the traditional lecturing method and

GEBL method, students stated that they felt much more relaxed and free to participate,

ask questions to peers and the lecturer and to give their views to their peers. The

learning environment created with the GEBL approach was more student-friendly and

students could concentrate on learning and gaining knowledge. In this regard, student

A’s sentiments epitomize the students’ views when he said:

“You just don’t have that platform, you are not free at all, you are afraid of the

other students, you are afraid, but this way, I am more free you see. I think the

lecturer was able to make the environment free. He made the environment so

free that you were so more able to ask questions anyhow and at any time...”

119


“... now you are feeling relaxed and analyse what is in front of you...”

4.2.3 Summary of Qualitative Data

From the qualitative data presented in section 4.2.1 and 4.2.2 and their subsections,

there is indication that students found that GEBL assisted them in learning factual

knowledge and understanding concepts, processes and procedures. Their problem

solving skills were also developed following the GEBL approach to analyse problems.

Their ability to communicate and to use MTHE 2 terms in groups was developed during

the group sessions.

4.3 Quantitative Data Analysis, Interpretation and Discussion

This section deals with quantitative data recorded with the relevant instruments

developed for this study. The mean is the sum of the values divided by the number of

values. The skewness is a measure of the asymmetry of the probability distribution of a

real-valued random variable. When the skewness value is negative the Bell-curve will lie

more to the right and the bulk of the values will lie to the right of the mean. The curve

will also have a longer tail on the left side caused by low number extreme cases. A

positive skew indicates that the tail on the right side is longer than the left side and the

http://en.wikipedia.org/wiki/Probability_distribution

http://en.wikipedia.org/wiki/Real_number

http://en.wikipedia.org/wiki/Random_variable

120

bulk of the values lie to the left of the mean. A zero value for skewness indicates that

the values are relatively evenly distributed on both sides of the mean. The curve will

have a symmetrical shape around the mean. Low values will be those below 40% and

high values those above 60%.

4.3.1 Addressing the First and Second Research Question

With reference to the first research question ‘What would be the effect of a guided

enquiry-based learning (GEBL) approach on mechanical engineering students’ factual

recall of MTHE 2 concepts?’ and the second research question: ‘What would be the

effect of a guided enquiry-based learning (GEBL) approach on mechanical engineering

students’ conceptual understanding of MTHE 2 concepts, principles and applications?’,

the following section gives a breakdown of the quantitative data presented.

In this section an overview of the descriptive statistics is given to show commonalities

and differences which occurred during the assessments. With regard to the tests and

final examination, all the lowest scored questions and all the highest scored questions

are presented and discussed. The overall performance of each test is highlighted and

discussed. Possible causes for poor the performance in certain questions are discussed.

Following this, suggestions to rectify the poorly performed section are made and

possible approaches to achieve this are explained.

121

Overall descriptive statistics

Statistics

T1 T1B T2 T3 FINALEXAM

N Valid 20 20 20 20 20

Missing 0 0 0 0 0

/Mean 46.2000 46.2000 42.4000 41.5505 48.6005

Standard. Error of Mean 3.52331 3.62782 1.77319 4.27973 4.76109

Median 45.5000 47.0000 43.5000 46.0000 55.5000

Mode 46.00a 45.00a 47.00 46.00a 58.00

Standard. Deviation 15.75670 16.22409 7.92996 19.13954 21.29224

Variance 248.274 263.221 62.884 366.322 453.359

Skewness .168 -.582 -.614 -.338 -.791

Standard. Error of Skewness .512 .512 .512 .512 .512

Kurtosis -1.111 .704 .243 .034 .316

Standard. Error of Kurtosis .992 .992 .992 .992 .992

Range 52.00 65.00 30.00 77.99 84.99

Minimum 20.00 8.00 25.00 .01 .01

Maximum 72.00 73.00 55.00 78.00 85.00

Sum 924.00 924.00 848.00 831.01 972.01

a. Multiple modes exist. The smallest value is shown

Table 4.2: Quantitative Statistics on the Students’ Overall Performance in Written Assessments

Test 2 had the lowest median (the middle value of all the results) of 43.5 with the final

examination showing the highest median of 55.5. The skewness of the histograms

shifted progressively from Test 1 to the Final Examination more to the right resulting in

a higher number of student concentration in the higher percentages. The exception

here was Test 3 which had a skewness of -0.338 which indicated a low number of

extreme cases below the mean (the average of all the results). This can be attributed to

the intervention improving student learning and knowledge retention as time

progressed even with larger volumes of work and increased degrees of difficulty.

122

Traditional teaching and learning methods were used to present the first module which

was covered in Test 1 and Test 1b. Low and high overall scores will be discussed and

possible cause and reasons for these low and high overall scores will be explained:

Data from Test 1 Theory Questions:

Statistics

T1.1 T1.2 T1.3 T1.4 T2.1 T2.2

N Valid 20 20 20 20 20 20

Missing 0 0 0 0 0 0

Mean 51.500 20.000 7.500 46.250 63.350 35.000

Standard. Error of Mean 5.5930 6.6886 3.1933 8.9360 3.6240 6.3867

Median 43.000 .000 .000 50.000 73.000 50.000

-Mode 43.0 .0 .0 .0 73.0 50.0

Standard. Deviation 25.0126 29.9122 14.2810 39.9630 16.2068 28.5620

Variance 625.632 894.737 203.947 1597.039 262.661 815.789

Skewness .370 1.041 1.845 .185 -1.523 .038

Standard. Error of Skewness .512 .512 .512 .512 .512 .512

Kurtosis .312 -.655 2.861 -1.524 1.950 -.395

Standard. Error of Kurtosis .992 .992 .992 .992 .992 .992

Range 100.0 75.0 50.0 100.0 64.0 100.0

Minimum .0 .0 .0 .0 18.0 .0

Maximum 100.0 75.0 50.0 100.0 82.0 100.0

Sum 1030.0 400.0 150.0 925.0 1267.0 700.0

Table 4.3: Quantitative Statistics on Theory Questions in Test 1

123

Figure 4.1: Theory Question 1.3 in Test 1 reflecting a low level of Conceptual Knowledge

In this question students had to explain their understanding of the gas constant. Many

of the students answered the question by giving a formula in terms of specific heat

capacities. This was mainly an interpretation error of what they had to do although

clear instructions were given to them prior to the commencement of the test. It can

also be mentioned that the relationships between gas constant and specific heat

capacities given by the students were in general correct although this was not asked.

The majority of the students interpreted the questions incorrectly and the mode (the

result most often recorded) was 0%. Question 1.3 had the lowest mean of 7.5 and the

124

highest positive skewness of 1.845. The low number extreme outliers (above or below

the mean) pushed the standard deviation up to 14.281.

Figure 4.2: Theory Question 2.1 in Test 1 reflecting a high level of Conceptual Knowledge

This question required the students to analyse the problem, explain which processes

were involved, which variables remained constant and which ones changed. They then

had to draw the pressure-volume diagram of the complete process. Most of the

students were able to analyse the problem correctly. They were also able to indicate

which variables remained constant and which ones changed and could reflect the

processes correctly on a pressure-volume diagram. Their conceptual knowledge in this

section of the work was of a high standard which enabled them to give the correct

125

response. Question 2.1 had the highest mean of 63.35 and highest negative skewness

of -1.523. The low number extreme cases pushed the standard deviation up to 16.207.

However, the central tendency (median) was 73% and the score that was recorded

most often (mode) was also 73%.

Data from Test 1 Analytical Questions:

Statistics

C1.2 C1.3 C2.2

N Valid 20 20 20

Missing 0 0 0

Mean 32.450 62.500 55.400

Standard. Error of Mean 6.5476 10.1793 7.8464

Median 25.000 100.000 50.000

Mode .0 100.0 100.0

Standard. Deviation 29.2817 45.5233 35.0900

Variance 857.418 2072.368 1231.305

Skewness .207 -.552 .108

Standard. Error of Skewness .512 .512 .512

Kurtosis -1.470 -1.632 -1.435

Standard. Error of Kurtosis .992 .992 .992

Range 75.0 100.0 94.0

Minimum .0 .0 6.0

Maximum 75.0 100.0 100.0

Sum 649.0 1250.0 1108.0

Table 4.4: Quantitative Statistics from Analytical Questions in Test 1

126

Figure 4.3: Analytical Question 1.2 in Test 1 reflecting a low level of Factual and Conceptual Knowledge

In this question, the students had to calculate the specific heat capacity of the gas in

the problem. Most of the errors occurred due to the incorrect approach to the solution

which resulted in an incorrect selection of formulae. Some students used standard

properties of air and applied it to an unknown gas which enabled them to use another

formula which would have had too many unknowns had they substituted correct data

for this gas. Some of the students used the wrong formula to determine the unknowns

by also assuming standard values for air which could not be applied to the gas in

question. The central tendency was 25% and the score most often recorded was 0%.

More attention must be given to this section emphasizing the fact that each gas has its

127

own unique properties and that these properties cannot be mixed up. Question 1.2 had

the lowest mean of 32.45, the lowest standard deviation of 29.2817 and the second

lowest skewness of 0.207.

Figure 4.4: Analytical Question 1.3 in Test 1 reflecting a high level of Factual Knowledge

In this question most students understood what needed to be determined and they

selected the correct formula to determine the answer. Here, the students were required

to tap into their memory and retrieve the correct formula taking into account the

information supplied in the problem and the variables available. The central tendency as

well as the score recorded most frequently was 100%. The data indicated that the

128

knowledge level of students varied from very low to high and that only a few students

could not solve the problem. Question 1.3 had the highest mean of 62.5, the highest

standard deviation of 45.5233 and the highest negative skewness of -0.512.

Data on Overall Results Test 1:

Statistics

TOTAL

N Valid 20

Missing 0

Mean 46.200

Standard. Error of Mean 3.5233

Median 45.500

Mode 46.0a

Standard. Deviation 15.7567

Variance 248.274

Skewness .168

Standard. Error of Skewness .512

Kurtosis -1.111

Standard. Error of Kurtosis .992

Range 52.0

Minimum 20.0

Maximum 72.0

Sum 924.0

a. Multiple modes exist. The smallest value is

shown

Table 4.5: Quantitative Statistics on Overall Performance in Test 1

129

Figure 4.5: Overall Performance in Test 1 with a combined Factual and Conceptual Knowledge achievement of 46.2%

From the data, 68% of the students scored between 30.443% and 61.775%. The

standard deviation is clearly influenced by the extreme cases in the tail on the right of

the histogram. The diagram has also small tails which explain the low values for the

kurtosis and the skewness. The positive skewness indicated that more students had

lower scores than higher scores for this assessment. The score most frequently

recorded was 46% which is 0.2% less than the mean score.

130

Data from Test 1b Theory Questions:

Statistics

T1.1 T1.2 T1.3 T1.4 T2.1 T2.2 T2.3

N Valid 20 20 20 20 20 20 20

Missing 0 0 0 0 0 0 0

Mean 47.700 94.350 27.500 2.000 44.700 6.000 16.500

Standard. Error of Mean 6.5386 2.9888 4.4054 2.0000 4.8678 2.5547 3.6473

Median 50.000 100.000 25.000 .000 40.000 .000 20.000

Mode 25.0 100.0 25.0 .0 33.0 .0 .0a

Standard. Deviation 29.2415 13.3664 19.7017 8.9443 21.7694 11.4248 16.3111

Variance 855.063 178.661 388.158 80.000 473.905 130.526 266.053

Skewness -.117 -3.307 -.186 4.472 1.217 1.845 .552

Standard. Error of Skewness .512 .512 .512 .512 .512 .512 .512

Kurtosis -1.278 12.275 -1.308 20.000 .649 2.861 -.714

Standard. Error of Kurtosis .992 .992 .992 .992 .992 .992 .992

Range 88.0 57.0 50.0 40.0 73.0 40.0 50.0

Minimum .0 43.0 .0 .0 20.0 .0 .0

Maximum 88.0 100.0 50.0 40.0 93.0 40.0 50.0

Sum 954.0 1887.0 550.0 40.0 894.0 120.0 330.0


Table 4.6: Quantitative Statistics on Theory Questions in Test 1b

131

Figure 4.6: Theory Question 1.2 in Test 1b reflecting a high level of Conceptual Knowledge

In this question the students were required to draw a pressure-volume diagram of the

complete process. To be able to do this a correct understanding of the various

processes involved was necessary as well as the ability to reflect the data on this

diagram correctly. Most students were able to answer this question correctly with only

certain individuals giving incorrect responses. Question 1.2 had the highest mean of

94.35, the third lowest standard deviation of 13.3664 and the highest negative

skewness of -3.307.

132

Figure 4.7: Theory Question 1.4 in Test 1b reflecting a low level of Conceptual Knowledge

This question consisted of three processes with process one followed by process two

and process two followed by process three. The question required from the students to

use their conceptual knowledge of the processes in question to determine the

relationship between two points. This would enable them to explain the process

between the two points and how the heat flow in this process would be determined.

However, to be able to give a correct response, a correct interpretation of the first two

processes had to be made. From the data it became clear that very few of them had

the correct understanding of what the process was and therefore could not give the

133

correct answer. The class as a whole scored low marks thus causing the skewness

leaning toward the left in the lower percentages. A possible cause could be the

students’ inability to use the pressure-volume diagram as a support to determine the

type of process involved in this question. More detailed exercises on this particular type

of approach could assist in handling similar problems. Question 1.4 had the lowest

mean of 2.0, the lowest standard deviation of 8.9443 and the highest positive skewness

of 4.472.

Data from Test 1b Analytical Questions:

Statistics

C1.3 C1.4 C2.2 C2.3

N Valid 20 20 20 20

Missing 0 0 0 0

Mean 76.550 .000 70.000 46.400

Standard. Error of Mean 7.4549 .0000 5.3311 7.4690

Median 92.000 .000 80.000 43.000

Mode 100.0 .0 80.0 43.0

Standard. Deviation 33.3395 .0000 23.8416 33.4025

Variance 1111.524 .000 568.421 1115.726

Skewness -1.438 -1.553 .148

Standard. Error of Skewness .512 .512 .512 .512

Kurtosis .819 2.766 -.929

Standard. Error of Kurtosis .992 .992 .992 .992

Range 100.0 .0 100.0 100.0

Minimum .0 .0 .0 .0

Maximum 100.0 .0 100.0 100.0

Sum 1531.0 .0 1400.0 928.0

Table 4.7: Quantitative Statistics on Analytical Questions in Test 1b

134

Figure 4.8: Analytical Question 1.3 in Test 1b reflecting a high level of Factual and Conceptual Knowledge

This question required the students to calculate the total heat flow for the complete

process. To be able to answer this question correctly, the students had to understand

what was meant by the term total heat flow and then they had to recall the correct

formula. Most of the students understood what total heat flow was and recalled the

correct formula. Question 1.3 had the highest mean of 76.55, the second highest

standard deviation of 33.3395 and the second highest skewness of -1.438.

135

Figure 4.9: Analytical Question 1.4 in Test 1b reflecting a low level of Factual and Conceptual Knowledge

All students scored zero for this question which explained the poor data. In this

question, the students needed an understanding of the process in question and which

variables (in this case pressure and temperature) would pose a danger to the device

and people. Very few students had a practical experience with this device and had

therefore to rely on their understanding and interpretation of the theory which they

have studied. An incorrect interpretation resulted in the use of incorrect and

inappropriate formulas. It became clear that more attention needed to be given to this

particular section and possibly an introduction of an experiment in the laboratory to

136

demonstrate the process from the initial point to the final position and then a return to

the original condition. A laboratory experiment would also allow for active participation

and group discussions for the students. Question 1.4 had the lowest mean of 0, the

lowest standard deviation of 0 and no skewness.

Data on Overall Results Test 1b:

Statistics

TOTAL

N Valid 20

Missing 0

Mean 46.200


Median 47.000

Mode 45.0a


Variance 263.221

Skewness -.582


Kurtosis .704


Range 65.0

Minimum 8.0

Maximum 73.0

Sum 924.0


shown

Table 4.8: Quantitative Statistics on Overall Performance in Test 1b

137

Figure 4.10: Overall Performance in Test 1 with a combined Factual and Conceptual Knowledge achievement of 46.2%

The standard deviation indicated that 68% of the students scored between 29.976%

and 62.424%. In this case the standard deviation was influenced by the lower extreme

cases as indicated by the tail on the left. The central tendency in this case was 47%

which was not affected by these low number extreme cases. The low value for the

skewness and kurtosis was as a result of the small tails. The negative skewness

indicated that more students scored higher values than lower values. The most frequent

score obtained by the students was 45%, very close to the mean of 46.2%. In this

138

question the majority of the students scored above 40% with only certain individuals

who scored between 0% and 20%.

GEBL was introduced and used for the remainder of the syllabus (modules 2-7). Low

and high scores will be discussed and possible reasons for the performance will be

given as well as possible solution to prevent poor performances in future. It is

important to draw the readers’ attention again to the fact that Test 2 was written on

four times more work (2 complete modules) than Test 1 and 1b (0.5 module each). The

degree of difficulty also increased progressively throughout the modules.

139

Data from Test 2 Theory Questions:

Statistics

T1.1 T1.2 T1.3 T1.4 T1.5 T1.6 T2.1 T2.2 T2.3

N Valid 20 20 20 20 20 20 20 20 20

Missing

0 0 0 0 0 0 0 0 0

Mean 20.000 42.600 52.500 60.000 20.000 18.350 5.000 28.350 77.000 Standard. Error of Mean

3.8899 7.2134 8.4876 11.2390

5.4290 6.1748 5.0000 7.3854 5.8535

Median 25.000 58.500 50.000 100.000

10.000 .000 .000 16.500 80.000

Mode 25.0 67.0 50.0 100.0 .0 .0 .0 .0 100.0 Standard. Deviation

17.3963

32.2595

37.9577

50.2625

24.2791

27.6144

22.3607

33.0283

26.1775

Variance

302.632

1040.674

1440.789

2526.316

589.474

762.555

500.000

1090.871

685.263

Skewness

1.333 -.405 -.086 -.442 .981 1.082 4.472 .696 -1.103

Standard. Error of Skewness

.512 .512 .512 .512 .512 .512 .512 .512 .512

Kurtosis 4.442 -1.647 -1.154 -2.018 .186 -.555 20.000 -.870 .380 Standard. Error of Kurtosis

.992 .992 .992 .992 .992 .992 .992 .992 .992

Range 75.0 83.0 100.0 100.0 80.0 67.0 100.0 100.0 80.0 Minimum

.0 .0 .0 .0 .0 .0 .0 .0 20.0

Maximum

75.0 83.0 100.0 100.0 80.0 67.0 100.0 100.0 100.0

Sum 400.0 852.0 1050.0 1200.0 400.0 367.0 100.0 567.0 1540.0


140

Figure 4.11: Theory Question in Test 2 reflecting a low level of Conceptual Knowledge

The question required from the students to explain the type of process in the question

bearing in mind all the information given. All students except one gave an incorrect

response. The majority of these responses were explaining the process which they had

to follow in answering the sub-questions posed, but did not answer sub-question in this

particular case. A possible cause of this could be the misinterpretation of the question.

In an attempt to illuminate this misunderstanding, in future the question must be

reworded so that it became clear regarding what was expected from the students.

Question 2.1 had the lowest mean of 5 and the highest positive skewness of 4.472.

141


In this question the students had to explain all the calculations which they had to

perform before they could do a volumetric analysis. The majority of the students gave

the correct answer showing that the group’s conceptual knowledge of this section of the

work was satisfactorily and that they used this to formulate their answers. Question 2.3

had the highest mean of 77 and the highest negative skewness of -1.103.

142


Statistics

C1.3 C1.4 C2.4 C2.5

N Valid 20 20 20 20

Missing 0 0 0 0

Mean 30.000 5.000 84.150 31.450

Standard. Error of Mean 9.8675 3.4412 4.9843 3.6088

Median .000 .000 91.000 27.000

Mode .0 .0 100.0 46.0

Standard. Deviation 44.1290 15.3897 22.2906 16.1391

Variance 1947.368 236.842 496.871 260.471

Skewness .939 2.888 -1.994 .397

Standard. Error of Skewness .512 .512 .512 .512

Kurtosis -1.046 7.037 3.839 -.690

Standard. Error of Kurtosis .992 .992 .992 .992

Range 100.0 50.0 82.0 59.0

Minimum .0 .0 18.0 8.0

Maximum 100.0 50.0 100.0 67.0

Sum 600.0 100.0 1683.0 629.0

Table 4.10: Quantitative Statistics on Analytical Questions in Test 2

143

Figure 4.13: Analytical Question in Test 2 reflecting a low level of Factual and Conceptual Knowledge

This question required the students to calculate the temperature at exit from the

compressor. Here, the students had to understand the process in and through the

compressor as well as the given information and how the given information could be

used to determine the temperature at exit. Except for two students, everybody gave the

wrong answer. Most of the students did not realise that the working fluid was air and

that standard properties could be used (not supplied in the question). Without these

properties, the question could not have been answered because the relevant formulae

would render too many unknowns. Possible means of overcoming this inability on the

144

student’s side would be to emphasise to the students the use of a systematic approach

in developing a solution, with the first step being to identify the working fluid. Question

1.4 had the lowest mean of 5.0 and the highest positive skewness of 2.888.


This question required the students to perform the calculations which they had listed in

Question 2.3. Question 2.3 was a theory question and the students had a very high

score for it which obviously resulted in the high score for Question 2.4. Here, the

students demonstrated their ability to physically perform the calculations which they

explained in the previous question. Question 2.4 had highest mean of 84.15 and the

145

highest negative skewness of -1.994. The small number of outliers between 0% and

20% pushed the standard deviation up to 22.291.


Statistics

TOTAL

N Valid 20

Missing 0

Mean 42.400


Median 43.500

Mode 47.0


Variance 62.884

Skewness -.614


Kurtosis .243


Range 30.0

Minimum 25.0

Maximum 55.0

Sum 848.0


146

Figure 4.15: Overall Performance in Test 2 reflecting a combined Factual and Conceptual Knowledge of 42.2%

Data for the overall performance in Question 2 indicated that 68% of the students

scored between 34.47% and 50.33%. The small tails in the histogram explain the low

values for the kurtosis and skewness. The median in this case is 43.5% with a

skewness of -0.614 which meant that this was the central tendency of the scores and

the score most frequently obtained by the students was 47% which was 5.4% higher

than the mean. The negative skewness indicated more high scores than lower scores

from the students.

147

The performance in Test 3 must be observed bearing in mind the fact that this test was

written on 3 modules of work which had six times more content than Test 1 and 1b and

also one module more than Test 2. The modules were still progressively becoming more

difficult and complex.

148

Data Test 3 Theory Questions:

Statistics

T1.1 T1.2 T1.3 T1.4 T1.5 T2.1

T2.2.

1

T2.2.

2 T2.3 T3.1 T3.2 T3.3 T4.1 T4.2 T4.3 T4.4 T4.5

N Vali

d

19 19 19 19 19 19 19 19 19 19 19 19 19 19 19 19 19

Miss

ing

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Mean 67.1

05

35.26

3

60.5

26

13.1

58

31.5

79

22.6

32

43.42

1

39.47

4

57.89

5

22.0

53

55.47

4

28.0

53

73.05

3

62.15

8

32.89

5

28.94

7

7.89

5

Stand

ard.

Error

of

Mean

6.90

70

8.284

7

6.70

92

5.18

95

6.85

11

5.28

94

7.845

9

7.481

9

10.99

12

7.23

11

7.301

5

6.40

43

8.668

2

8.340

8

8.122

9

7.709

8

3.84

87

Media

n

50.0

00

40.00

0

75.0

00

.000 25.0

00

20.0

00

50.00

0

50.00

0

100.0

00

.000 63.00

0

33.0

00

100.0

00

83.00

0

25.00

0

25.00

0

.000

Mode 50.0 .0 75.0 .0 .0a .0 .0a 50.0 100.0 .0 63.0 .0 100.0 83.0a .0 .0 .0

Stand

ard.

Deviat

ion

30.1

070

36.11

22

29.2

449

22.6

207

29.8

632

23.0

560

34.19

93

32.61

28

47.90

95

31.5

198

31.82

66

27.9

155

37.78

37

36.35

67

35.40

70

33.60

63

16.7

760

Varian

ce

906.

433

1304.

094

855.

263

511.

696

891.

813

531.

579

1169.

591

1063.

596

2295.

322

993.

497

1012.

930

779.

275

1427.

608

1321.

807

1253.

655

1129.

386

281.

433

Skewn

ess

-

.379

.470 -

.719

1.17

0

.524 .826 .096 .227 -.346 1.30

9

-.410 .341 -

1.142

-.623 .682 .908 1.99

8

Stand

ard.

Error

of

Skewn

ess

.524 .524 .524 .524 .524 .524 .524 .524 .524 .524 .524 .524 .524 .524 .524 .524 .524

Kurtos

is

-

.521

-

1.116

.257 -

.718

-

.329

-

.098

-

1.156

-.613 -

1.952

.526 -.403 -

1.46

9

-.066 -.988 -.780 -.015 2.81

1

Stand

ard.

Error

of

Kurtos

is

1.01

4

1.014 1.01

4

1.01

4

1.01

4

1.01

4

1.014 1.014 1.014 1.01

4

1.014 1.01

4

1.014 1.014 1.014 1.014 1.01

4

Range 100.

0

100.0 100.

0

50.0 100.

0

70.0 100.0 100.0 100.0 100.

0

100.0 67.0 100.0 100.0 100.0 100.0 50.0

Minim

um

.0 .0 .0 .0 .0 .0 .0 .0 .0 .0 .0 .0 .0 .0 .0 .0 .0

Maxim

um

100.

0

100.0 100.

0

50.0 100.

0

70.0 100.0 100.0 100.0 100.

0

100.0 67.0 100.0 100.0 100.0 100.0 50.0

Sum 127

5.0

670.0 115

0.0

250.

0

600.

0

430.

0

825.0 750.0 1100.

0

419.

0

1054.

0

533.

0

1388.

0

1181.

0

625.0 550.0 150.

0



149


This question required the students to draw a flow diagram of the Rankine cycle. Here,

the students had to use their conceptual knowledge of the operation of the Rankine

cycle and all the components it consisted of as well as the relationship between the

various components within the plant. The standard deviation was increased by the

outliers and the highest concentration of scores was in the upper limits. The majority of

the students had a good understanding of this section and could give a correct

response. The central tendency for this question and the score most frequently

150

recorded was 100%. Question 4.1 had the highest mean of 73.05 and the highest

negative skewness of -1.142.

Figure 4.17: Theory Question 4.5 in Test 3 reflecting a low level of Conceptual Knowledge

This question required the students to explain their understanding of the brake thermal

efficiency of the Rankine cycle and what exactly it measured. From the data it was clear

that not many students had a proper understanding of what the brake thermal

efficiency was or what it was used for. A possible strategy to rectify this would be to

spend more time on this particular section during problem solving sessions and to

present students with more problems which incorporate the brake thermal efficiency.

151

Question 4.5 had the lowest mean of 7.89 and the highest positive skewness of 1.998.


Statistics

C1.3 C1.4 C1.5 C2.2.1 C2.2.2 C2.3 C3.3 C4.3 C4.4 C4.5

N Valid 19 19 19 19 19 19 19 19 19 19

Missing 0 0 0 0 0 0 0 0 0 0

Mean 26.368 8.789 11.474 67.105 61.474 76.316 89.421 68.368 46.053 10.000

Standard.

Error of

Mean

5.8715 5.0144 4.5917 7.6598 9.6325 7.0175 4.2270 10.0374 9.6092 3.4918

Median 17.000 .000 .000 75.000 67.000 100.000 100.000 100.000 50.000 .000

Mode 17.0 .0 .0 100.0 100.0 100.0 100.0 100.0 .0 .0

Standard.

Deviation

25.5934 21.8571 20.0149 33.3881 41.9873 30.5888 18.4250 43.7521 41.8854 15.2206

Variance 655.023 477.731 400.596 1114.766 1762.930 935.673 339.480 1914.246 1754.386 231.667

Skewness 1.320 2.366 2.790 -.599 -.609 -.924 -1.251 -.765 .119 .902

Standard.

Error of

Skewness

.524 .524 .524 .524 .524 .524 .524 .524 .524 .524

Kurtosis 2.416 4.385 9.284 -.998 -1.334 .038 -.402 -1.369 -1.671 -1.289

Standard.

Error of

Kurtosis

1.014 1.014 1.014 1.014 1.014 1.014 1.014 1.014 1.014 1.014

Range 100.0 67.0 83.0 100.0 100.0 100.0 43.0 100.0 100.0 33.0

Minimum .0 .0 .0 .0 .0 .0 57.0 .0 .0 .0

Maximum 100.0 67.0 83.0 100.0 100.0 100.0 100.0 100.0 100.0 33.0

Sum 501.0 167.0 218.0 1275.0 1168.0 1450.0 1699.0 1299.0 875.0 190.0

Table 4.13: Quantitative Statistics on Analytical Questions in Test 3

152

Figure 4.18: Analytical Question 1.4 in Test 3 reflecting a low level of Factual and Conceptual Knowledge

This question required the students to determine the percentage of heat that was

converted into work done. To be able to answer this question correctly, the students

had to have an understanding of the relationship between heat, work done and change

in internal energy. This was a case of conceptual understanding and factual recall of the

specific formula. From the data it is clear that most students could not answer this

question correctly. The central tendency in this case was 0% with the score that was

recorded most frequently also at 0%. The low number of extreme cases pushed the

standard deviation up to 21.857. Looking at the responses in their scripts, a possible

cause was the misinterpretation of the question. Some of the students could give the

153

formula correctly but could not perform the percentage calculation. It was not that they

did not know how to do it but they were definitely not aware that this was what had to

be done. In future, similar question would have to be worded differently to reduce

possible misunderstandings. Question 1.4 had the lowest mean of 8.79 and the second

highest positive skewness of 2.366.


This question required the students to determine the degree of dryness in a steam

pipeline. The standard deviation was increased by the outliers and the central tendency

154

as well as the score recorded most often was 100%. Here the students demonstrated

their ability to correctly interpret the question and also to recall the formulas correctly

for this section of the work. Question 3.3 had the highest mean of 89.42 and the

highest negative skewness of -1.251.


Statistics

TOTAL

N Valid 19

Missing 0

Mean 43.737


Median 46.000

Mode 46.0a


Variance 285.760

Skewness -.035


Kurtosis -.212

Standard. Error of Kurtosis 1.014

Range 62.0

Minimum 16.0

Maximum 78.0

Sum 831.0


shown


155

Figure 4.20: Overall Performance in Test 3 reflecting a combined Factual and Conceptual Knowledge 43.74%

The data indicated that 68% of the students scored between 26.836% and 60.644%.

The small number of outliers pushed the standard deviation up to 16.904, however the

central tendency for the scores was 46% regardless of a small number of high values

that were recorded between 50% and 60%. The small tails gave low values for

skewness. The small negative skewness of -0.35 indicated that only a few more

students obtained higher scores than those whom obtained lower scores.

156

Data from Final Examination Theory Questions:

Statistics

T1 T2 T3 T4 T5 T6 T7 T8 T9

N Valid 15 15 15 15 15 15 15 15 15

Missing 0 0 0 0 0 0 0 0 0

Mean 32.493 42.133 50.000 56.733 57.333 32.800 65.133 34.667 6.667

Standard. Error of

Mean

7.9737 9.1879 11.9523 5.1533 8.0750 8.5106 7.3672 6.8914 2.9547

Median 30.000 33.000 50.000 67.000 60.000 33.000 72.000 40.000 .000

Mode .1a .0a .0a 67.0 30.0a .0 72.0 .0a .0

Standard. Deviation 30.8820 35.5846 46.2910 19.9588 31.2745 32.9614 28.5329 26.6905 11.4434

Variance 953.699 1266.267 2142.857 398.352 978.095 1086.457 814.124 712.381 130.952

Skewness .503 .514 .000 .233 -.184 .495 -1.196 -.061 1.176

Standard. Error of

Skewness

.580 .580 .580 .580 .580 .580 .580 .580 .580

Kurtosis -1.045 -.597 -1.974 -.181 -1.046 -1.053 .892 -1.226 -.734

Standard. Error of

Kurtosis

1.121 1.121 1.121 1.121 1.121 1.121 1.121 1.121 1.121

Range 90.0 100.0 100.0 67.0 100.0 92.0 100.0 80.0 25.0

Minimum .0 .0 .0 33.0 .0 .0 .0 .0 .0

Maximum 90.0 100.0 100.0 100.0 100.0 92.0 100.0 80.0 25.0

Sum 487.4 632.0 750.0 851.0 860.0 492.0 977.0 520.0 100.0


Table 4.15: Quantitative Statistics from Theory Question in Final Examination

157

Figure 4.21: Theory Question 7 in the Final Examination reflecting a high level of Conceptual Knowledge

This question required the students to complete an attached diagram and fill in all the

relevant detail. The students needed their conceptual knowledge (recalling the detailed

diagram that were presented to them in the notes) of this particular section to complete

the diagram of the wet and dry air pumps. In this question only three students scored

below 40% with the rest achieving a score above 60%. The outliers in the lower

percentages pushed the standard deviation up to 28.533. The central tendency in this

case was 72% and the score recorded most frequently was also 72%. A satisfactory

level of understanding of the theory was demonstrated as revealed by the data.

158

Question 7 had the highest mean of 65.13 and the highest negative skewness of -

1.196.

Figure 4.22: Theory Question 9 from the Final Examination reflecting a low level of Conceptual Knowledge

This question required the students to explain what the products of combustion will be

with insufficient air supplied and how the heat released during combustion will be

affected. The section on combustion mainly concentrated on complete combustion, but

the effects of too much and too little air supplied were discussed. The students had to

have a proper understanding of the conceptual process and knowledge and ability to

use the information to determine what result, the insufficient air supply would cause.

159

Only four students had an idea, although vague, regarding what was required from

them. In future, more time must be spent on discussing non-standard conditions which

was not normal or ideal so that the students could develop the ability to think outside of

the box, manipulating the knowledge which they had with respect to the ideal

conditions. This can be assisted through big group or small group discussions or even a

group assignment. Question 9 had the lowest mean of 6.67 and the highest positive

skewness of 1.176.

160

Data from Final Examination Analytical Questions:

Statistics

C1 C2 C3 C4 C5 C6 C7 C8 C9 C10 C11 C12 C13 C14 C15 C16

N Vali

d

15 15 15 15 15 15 15 15 15 15 15 15 15 15 15 15

Miss

ing

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Mean 42.00

0

52.00

0

22.66

7

3.33

3

89.2

67

74.46

7

6.66

7

83.3

33

66.66

7

80.00

0

31.0

00

15.53

3

44.6

67

53.33

3

79.40

0

65.66

7

Standa

rd.

Error

of

Mean

11.43

10

8.462

8

9.127

0

3.33

33

4.54

03

9.608

5

6.66

67

7.96

82

8.333

3

9.511

9

7.61

76

9.120

8

7.85

99

13.33

33

8.175

9

8.658

4

Media

n

50.00

0

60.00

0

.000 .000 100.

000

100.0

00

.000 100.

000

50.00

0

100.0

00

33.0

00

.000 50.0

00

100.0

00

100.0

00

70.00

0

Mode .0 40.0a .0 .0 100.

0

100.0 .0 100.

0

50.0a 100.0 33.0 .0 50.0a 100.0 100.0 100.0

Standa

rd.

Deviati

on

44.27

19

32.77

63

35.34

86

12.9

099

17.5

844

37.21

34

25.8

199

30.8

607

32.27

49

36.83

94

29.5

030

35.32

48

30.4

412

51.63

98

31.66

52

33.53

39

Varian

ce

1960.

000

1074.

286

1249.

524

166.

667

309.

210

1384.

838

666.

667

952.

381

1041.

667

1357.

143

870.

429

1247.

838

926.

667

2666.

667

1002.

686

1124.

524

Skewn

ess

.302 -.148 1.380 3.87

3

-

1.71

1

-

1.220

3.87

3

-

1.79

2

-.426 -

1.632

.876 2.179 .327 -.149 -

1.486

-.590

Standa

rd.

Error

of

Skewn

ess

.580 .580 .580 .580 .580 .580 .580 .580 .580 .580 .580 .580 .580 .580 .580 .580

Kurtosi

s

-

1.791

-.984 .443 15.0

00

1.88

1

.164 15.0

00

2.62

5

-.666 1.320 .675 3.471 -

.091

-

2.308

1.422 -.742

Standa

rd.

Error

of

Kurtosi

s

1.121 1.121 1.121 1.12

1

1.12

1

1.121 1.12

1

1.12

1

1.121 1.121 1.12

1

1.121 1.12

1

1.121 1.121 1.121

Range 100.0 100.0 100.0 50.0 50.0 100.0 100.

0

100.

0

100.0 100.0 100.

0

100.0 100.

0

100.0 100.0 100.0

Minim

um

.0 .0 .0 .0 50.0 .0 .0 .0 .0 .0 .0 .0 .0 .0 .0 .0

Maxim

um

100.0 100.0 100.0 50.0 100.

0

100.0 100.

0

100.

0

100.0 100.0 100.

0

100.0 100.

0

100.0 100.0 100.0

Sum 630.0 780.0 340.0 50.0 1339

.0

1117.

0

100.

0

1250

.0

1000.

0

1200.

0

465.

0

233.0 670.

0

800.0 1191.

0

985.0


Table 4.16: Quantitative Statistics from Analytical Question in Final Examination

161

Figure 4.23: Analytical Question 4 in the Final Examination reflecting a low level of Factual and Conceptual Knowledge

This question required the students to determine the overall change in enthalpy of the

gas. The students had to use both their factual and conceptual knowledge of this

section of the work in order for them to be able to give the correct answer. They had to

understand the complete process as well as the relationship between initial and final

enthalpy of the gas. Only one student scored 50% and the rest obtained a score of 0%.

These results indicated a definite lack of knowledge in this particular area and in the

future, problem solving group sessions would have to concentrate more on this.

Students must also be made aware of the fact that they must look at specific details

162

when they dealt with a problem, and should also consider the bigger picture to find

relationships between initial and final conditions. Question 4 had the lowest mean of

3.33 and the highest positive skewness of 3.873.

Figure 4.24: Analytical Question 5 in the Final Examination reflecting a high level of Factual and Conceptual Knowledge

This question required the students to determine the work done by steam during

heating thereof at constant pressure. The students had to understand the conceptual

process and knowledge and had to recall the correct formula (factual knowledge) and

substitute the correct values to determine the answer. Question 5 had the highest mean

of 89.27 and the second highest negative skewness of -1.711.

163

Data from Final Examination Overall Results:

Statistics

TOTAL

N Valid 19

Missing 0

Mean 51.158


Median 56.000

Mode 58.0


Variance 340.474

Skewness -.625


Kurtosis .309


Range 74.0

Minimum 11.0

Maximum 85.0

Sum 972.0

Table 4.17: Quantitative Statistics from Overall Performance in Final Examination

164

Figure 4.25: Overall Performance in the Final Examination reflecting a combined Factual and Conceptual Knowledge achievement of 51.16%

From the data 68% of the students scored between 32.706% and 69.91%. The central

tendency in the scores was 56% although a small number of extreme high values were

recorded in the vicinity of the median. The score most often recorded was 58% as

indicated on the histogram, which was 7.16% higher than the mean. Low skewness

resulted in an almost normal curve. The negative skewness also indicated that a larger

number of high scores than lower scores were obtained.

165

Reliability statistics on Tests 1, 1B, 2, 3 and Final Examination:

Reliability Statistics

Cronbach's

Alpha

Cronbach's

Alpha Based on

Standardized

Items N of Items

.879 .936 10

Table 4.18: Quantitative Statistics on Reliability for Tests 1, 1b, 2, 3 and Final Examination

The Cronbach’s Alpha test for internal consistency of the instruments gave a score of

= 0.88 for the written assessments. The Cronbach’s Alpha reliability coefficient ranges

from 0 to 1. The closer the value of alpha is to 1.0 the greater the internal consistency

of the instruments.

4.3.2 Addressing the Third Research Question

In this study, the third research question ‘What would be the effect of a guided enquiry-

based learning (GEBL) approach on mechanical engineering students’ ability to

communicate procedures and processes related to MTHE 2?’ the following section

presents data from oral tests:

166

Data from Oral Test 1:

Statistics

T1 T4 T7 T11 T22 T26 T31 T33 T34 T39 T41 T42 T43

N Valid 7 7 7 7 7 7 7 7 7 7 7 7 7

Missin

g

0 0 0 0 0 0 0 0 0 0 0 0 0

Mean 85.714 42.85

7

91.42

9

91.42

9

67.857 38.000 71.429 7.143 .000 57.000 28.571 57.143 32.143

Standard

. Error of

Mean

14.285

7

9.607

6

5.947

6

4.040

6

16.104

5

13.494

3

14.869

0

7.142

9

.000

0

14.494

7

14.869

0

20.203

1

13.041

0

Median 100.00

0

33.00

0

100.0

00

100.0

00

100.00

0

33.000 100.00

0

.000 .000 50.000 .000 100.00

0

25.000

Mode 100.0 33.0a 100.0 100.0 100.0 33.0 100.0 .0 .0 33.0a .0 100.0 .0

Standard

.

Deviatio

n

37.796

4

25.41

93

15.73

59

10.69

04

42.608

4

35.702

5

39.339

8

18.89

82

.000

0

38.349

3

39.339

8

53.452

2

34.503

3

Variance 1428.5

71

646.1

43

247.6

19

114.2

86

1815.4

76

1274.6

67

1547.6

19

357.1

43

.000 1470.6

67

1547.6

19

2857.1

43

1190.4

76

Skewnes

s

-2.646 -.559 -1.760 -.374 -.796 .782 -1.115 2.646

-.151 1.115 -.374 .359

Standard

. Error of

Skewnes

s

.794 .794 .794 .794 .794 .794 .794 .794 .794 .794 .794 .794 .794

Kurtosis 7.000 -.458 2.361 -2.800 -1.301 .246 .273 7.000 -1.405 .273 -2.800 -2.090

Standard

. Error of

Kurtosis

1.587 1.587 1.587 1.587 1.587 1.587 1.587 1.587 1.58

7

1.587 1.587 1.587 1.587

Range 100.0 67.0 40.0 20.0 100.0 100.0 100.0 50.0 .0 100.0 100.0 100.0 75.0

Minimum .0 .0 60.0 80.0 .0 .0 .0 .0 .0 .0 .0 .0 .0

Maximu

m

100.0 67.0 100.0 100.0 100.0 100.0 100.0 50.0 .0 100.0 100.0 100.0 75.0

Sum 600.0 300.0 640.0 640.0 475.0 266.0 500.0 50.0 .0 399.0 200.0 400.0 225.0


Table 4.19: Quantitative Statistics from Oral Test 1

167

Figure 4.26: Question 7 in Oral Test 1 reflecting a high level of Conceptual Knowledge

In this question, the students had to explain to the examiner which components

constituted the steady flow energy equation. The scores varied between 60% and

100% with the majority of the students getting 100% for the question which resulted in

the mode being 100%. One student obtained 60% and one 80% which resulted in the

standard deviation being pushed up by these outliers. Question 7 had the highest mean

of 91.43 and the second highest negative skewness of -1.760.

168


In this question, the students had to explain which products would appear in the table

for the mass analysis of a specific fuel. The histogram showed closeness to a normal

curve with the mode and the median being 100. Most students could express

themselves clearly and could list the products of combustion correctly. The scores

varied between 80% and 100%. Question 11 together with question 7 had the highest

mean of 91.43 and a low negative skewness of -0.374.

169

Figure 4.28: Question 34 in Oral Test 1 reflecting a low level of Conceptual Knowledge

In this question, the students had to explain how the water treatment of an electrode

boiler differed from that of a normal coal fired boiler. On this particular section of the

work, the students were given a project with certain questions to which they had to find

answers. One of these questions was to investigate the difference between coal fired

and electrode boilers with regard to their construction, operation and water treatment.

Here the students hat to tap into their memory and retrieve the information which they

had found during their project. Not a single student could answer this question correctly

as revealed by the data. A possible cause to the problem could be that students did not

170

regard the contents of their project to be included in assessments and once they have

submitted it, they forget about it. To overcome this, feedback sessions can be

introduced on completed projects as part of a group activity and in this way discussing

their findings and making them aware of the importance and relevance of project work

to enrich the content knowledge in the course work modules. Question 34 had the

lowest mean of 0, and a skewness of 0.

171

Data from Oral Test 2:

Statistics

T2 T3 T5 T8 T9 T10 T13 T21 T25 T30 T37 T38 T40 T44 T46

N Valid 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8

Missi

ng

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Mean 31.25

0

100.0

00

93.75

0

83.25

0

86.25

0

56.25

0

12.50

0

65.12

5

37.50

0

71.87

5

12.50

0

83.25

0

50.00

0

12.50

0

50.12

5

Standa

rd.

Error

of

Mean

13.15

26

.0000 6.250

0

9.480

7

12.38

34

17.51

91

9.449

1

8.463

0

13.23

28

11.01

69

12.50

00

4.410

8

12.50

00

12.50

00

12.32

95

Median 25.00

0

100.0

00

100.0

00

100.0

00

100.0

00

75.00

0

.000 75.00

0

25.00

0

75.00

0

.000 83.00

0

50.00

0

.000 50.00

0

Mode .0 100.0 100.0 100.0 100.0 100.0 .0 75.0 .0a 100.0 .0 83.0 50.0 .0 50.0

Standa

rd.

Deviati

on

37.20

12

.0000 17.67

77

26.81

55

35.02

55

49.55

16

26.72

61

23.93

70

37.42

80

31.16

06

35.35

53

12.47

57

35.35

53

35.35

53

34.87

30

Varianc

e

1383.

929

.000 312.5

00

719.0

71

1226.

786

2455.

357

714.2

86

572.9

82

1400.

857

970.9

82

1250.

000

155.6

43

1250.

000

1250.

000

1216.

125

Skewn

ess

.824

-

2.828

-

1.384

-2.775 -.312 2.339 -.647 .790 -.286 2.828 .080 .404 2.828 -.574

Standa

rd.

Error

of

Skewn

ess

.752 .752 .752 .752 .752 .752 .752 .752 .752 .752 .752 .752 .752 .752 .752

Kurtosi

s

-.152

8.000 .399 7.756 -2.358 5.469 .753 -.728 -

1.984

8.000 -.698 -.614 8.000 -.930

Standa

rd.

Error

of

Kurtosi

s

1.481 1.481 1.481 1.481 1.481 1.481 1.481 1.481 1.481 1.481 1.481 1.481 1.481 1.481 1.481

Range 100.0 .0 50.0 67.0 100.0 100.0 75.0 79.0 100.0 75.0 100.0 33.0 100.0 100.0 88.0

Minimu

m

.0 100.0 50.0 33.0 .0 .0 .0 21.0 .0 25.0 .0 67.0 .0 .0 .0

Maxim

um

100.0 100.0 100.0 100.0 100.0 100.0 75.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 88.0

Sum 250.0 800.0 750.0 666.0 690.0 450.0 100.0 521.0 300.0 575.0 100.0 666.0 400.0 100.0 401.0


Table 4.20: Quantitative Statistics from Oral Test 2

172


In this question, the students had to define the term ‘reversible process.’ Here, the

students had to use their conceptual knowledge of this section to explain the answer

correctly. As indicated by the data everybody had 100% for this question. Question 3

had the highest mean of 100 and a skewness of 0.

173


In this question, the students had to explain to the examiner how the amount of vapour

would be determined in the case of a liquid and gaseous fuel when calculating the

lower calorific values of the fuels. Only one student scored 75% and another 25%, the

rest had 0%. As indicated on the histogram, most students failed this question. The

standard deviation was pushed up by the single outliers in the high percentages. To be

able to answer this question correctly, students had to use their factual and conceptual

knowledge of this section of the work. The data revealed that most students could not

do this, which showed that students had to spend more time on this section during

problem solving sessions with a variety of problems containing higher and lower

174

calorific values. Question 13 had the lowest mean of 12.5 and a high positive skewness

of 2.339.


In this question, the students had to explain the reasons for carrying out ‘blow-down’

on boiler plants. This was part of a boiler project which students had to do by visiting

industry and finding answers to a list of questions given to them. Student’s general

response during the oral test was ‘it is done automatically’ which is not the answer to

the question although their statement was correct for some plants. Only one student

gave the correct answer and rest did not know why blow-down was carried out. One

possible reason for this poor performance is that the students did not regard the

175

content of project work as being part of the syllabus on which they would be assessed

upon. Another reason could be that project work was normally done in groups and that

some of the group members were passive and copied the work done by the others. In

future feedback on these projects must be introduced into the group sessions for

discussion. Question 37 had the lowest mean of 12.5 and the highest positive skewness

of 2.828.


In this question, the students had to explain how air entered a surface condenser. This

question required the students to use their conceptual knowledge on this section of the

syllabus to give the correct explanation. One student could do this, which meant that all

176

the others did not understand how air entered the system, resulting in the central

tendency to be 0. This resulted in a median and mode of 0. The low number of outliers

in the higher percentages increased the standard deviation to 35.355. During the

introduction of condensers to the students, all important aspects were covered and

explained. However students should be given extra time to work on this in their groups

and more time for discussion must be allowed. Question 44 had the lowest mean of

12.5 and highest positive skewness of 2.828.

Data from Oral Tests 1 and 2 Overall Results:

Statistics

TOTAL

N Valid 15

Missing 0

Mean 58.467


Median 61.000

Mode 64.0a


Variance 254.124

Skewness -.830


Kurtosis -.241


Range 51.0

Minimum 26.0

Maximum 77.0

Sum 877.0


shown

Table 4.21: Quantitative Statistics from Overall Performance in Oral Tests 1 and 2

177

Figure 4.33: Overall Performance in Oral Tests 1 and 2 reflecting a Conceptual Knowledge level 58.47%

The attention of the reader is once again drawn to the fact that the final examination

was written on the entire syllabus (seven modules) which was covered over a period of

13 weeks. Students used the GEBL approach when preparing for the examination in

groups.

178

4.3.3 Structured Questionnaire

A questionnaire (see Appendix 1) was handed out to 15 students to determine their

opinion regarding the GEBL process which they were subjected to for one semester.

The research question/s addressed by each item will be indicated in brackets. From the

data the following findings were made:

Item 1 (RQ 3):

Statistics

Q1

N Valid 15

Missing 0

Mean 1.4667

Standard. Error of Mean .21529

Median 1.0000

Mode 1.00

Standard. Deviation .83381

Variance .695

Skewness 2.253


Kurtosis 5.776


Range 3.00

Minimum 1.00

Maximum 4.00

Sum 22.00

Table 4.22: Quantitative Statistics from Question 1 in Structured Questionnaire

179

Figure 4.34: Question 1 from the Structured Questionnaire reflecting 67% of students ‘strongly agree’

The questionnaire had a Likert-type scale of 1 to 5 with 1 = strongly agree, 2 = agree,

3 = neutral, 4 = disagree, 5 = strongly disagree. From the data 67% of the students

scored 0.636 (rounded off to 1) to 2.304 (rounded off to 2). The most common score

was indicated by the mode as ‘1’. The students therefore ‘strongly agreed’ that they

enjoyed the group sessions, 27% ‘agreed’ that they enjoyed the group sessions and 6%

‘disagreed’ that they enjoyed the group sessions. The standard deviation was influenced

by the single high score of ‘4’ (disagree). The skewness had a high positive value which

meant that the concentration of responses was in the lower scale between ‘1’ and ‘2’

180

and the high positive kurtosis (2.776 higher than the normal) indicated a peak in this

area.

Item 2 (RQ 1 & 2):

Statistics

Q2

N Valid 15

Missing 0

Mean 1.2667


Median 1.0000

Mode 1.00


Variance .210

Skewness 1.176


Kurtosis -.734


Range 1.00

Minimum 1.00

Maximum 2.00

Sum 19.00


181

Figure 4.35: Question 2 from the Structured Questionnaire reflecting 73% of students ‘strongly agree’

73% ‘strongly agreed’ that the EBL helped them to analyse problems more effectively

and 27% ‘agreed’ and no other responses were recorded. The data indicated that both

the median and mode was ‘1’ (strongly agree) and that 68% of the students gave this

response. The positive skewness indicated a higher concentration of students in the

lower percentages of the scale.

182

Item 3 (RQ 1 & 2):

Statistics

Q3

N Valid 15

Missing 0

Mean 2.0667


Median 2.0000

Mode 3.00


Variance .781

Skewness -.142


Kurtosis -1.783


Range 2.00

Minimum 1.00

Maximum 3.00

Sum 31.00


183

Figure 4.36: Question 3 from the Structured Questionnaire reflecting 33% of students ‘strongly agree’ and 27% ‘agree’

33% of the students ‘strongly agreed’ that when working alone, the EBL approach

helped them to analyse problems more effectively, 27% ‘agreed’ and 40% assumed a

‘neutral’ position.

184

Item 4 (RQ 1 & 2):

Statistics

Q4

N Valid 15

Missing 0

Mean 1.4000


Median 1.0000

Mode 1.00


Variance .400

Skewness 1.407


Kurtosis 1.264


Range 2.00

Minimum 1.00

Maximum 3.00

Sum 21.00


185

Figure 4.37: Question 4 from the Structured Questionnaire reflecting 67% of the students ‘strongly agree’

67% of the students ‘strongly agreed’ that the EBL method helped them to understand

work better and not to just memorise it, 27% ‘agreed’ and 6% assumed a ‘neutral’

position.

186

Item 5 (RQ 1 & 2):

Statistics

Q5

N Valid 15

Missing 0

Mean 1.8000


Median 2.0000

Mode 2.00


Variance .314

Skewness -.112


Kurtosis .378


Range 2.00

Minimum 1.00

Maximum 3.00

Sum 27.00


187

Figure 4.38: Question 5 from the Structured Questionnaire reflecting 27% of the students ‘strongly agree’ and 67% ‘agree’

27% of the students ‘strongly agreed’ that the EBL method helped them to develop the

ability to solve problems on their own, 67% ‘agreed’ and 6% assumed a ‘neutral’

position.

188

Item 6 (RQ 1 & 2):

Statistics

Q6

N Valid 15

Missing 0

Mean 1.5333


Median 1.0000

Mode 1.00


Variance .695

Skewness 2.012


Kurtosis 4.867


Range 3.00

Minimum 1.00

Maximum 4.00

Sum 23.00


189

Figure 4.39: Question 6 from the Structured Questionnaire reflecting 60% of the students ‘strongly agree’

60% of the students ‘strongly agreed’ that the Thermodynamics booklet with questions

answer and discussions helped them to understand the work better, 33% ‘agreed’ and

6% ‘disagreed’.

190

Item 7 (RQ 1 & 2):

Statistics

Q7

N Valid 15

Missing 0

Mean 1.8667


Median 2.0000

Mode 2.00


Variance .410

Skewness .103


Kurtosis -.127


Range 2.00

Minimum 1.00

Maximum 3.00

Sum 28.00


191

Figure 4.40: Question 7 from the Structured Questionnaire reflecting 27% of the students ‘strongly agree and 60% ‘agree’

27% of the students ‘strongly agreed’ that the Thermodynamics booklets’ additional

questions and answers helped them to understand and analyse new problems better,

60% ‘agreed’ and 13% assumed a ‘neutral’ position.

192

Item 8:

Statistics

Q8

N Valid 15

Missing 0

Mean 1.8000


Median 2.0000

Mode 2.00


Variance .743

Skewness 1.205


Kurtosis 1.800


Range 3.00

Minimum 1.00

Maximum 4.00

Sum 27.00


193


40% of the students ‘strongly agreed’ that the EBL method and help them understand

other courses better, 47% ‘agreed’, 6% assumed a ‘neutral’ position and 6%

‘disagreed’.

194

Item 9:

Statistics

Q9

N Valid 15

Missing 0

Mean 1.6000


Median 1.0000

Mode 1.00


Variance 1.114

Skewness 2.640


Kurtosis 8.173


Range 4.00

Minimum 1.00

Maximum 5.00

Sum 24.00


195


60% of the students ‘strongly agreed’ that the EBL method should also be introduced

into other course, 33% ‘agreed’ and 6% ‘strongly disagreed’. However one student who

indicated ‘strongly disagreed’ on the Likert-type scale gave an explanation contradicting

this in the open-ended questions. Comparing these responses with the interview

responses, all students were in favour of introducing this method into their other course

and a conclusion could therefore be made that the single response of ‘strongly disagree’

was due to a misinterpretation of the questionnaire question.

196

The overall impression from the responses indicated that students enjoyed working

together in groups, listening to each others’ opinions and views. They also enjoyed

sharing their opinions with their peers. An exchange of information took place during

discussions benefiting all group members. There was also a strong indication that this

approach helped them to solve problems in groups and on their own more effectively.

This could be as a result of the skill which they had developed to analyse problems

following the systematic approach illustrated in the EBL booklet. The students also

wanted this method of teaching and learning to be introduced into other courses which

meant that students found this to be a more effective method of transferring

knowledge and that also made MTHE2 which seemed to be a ‘difficult course’ to be

easier and more understandable.

4.3.4 Summary of Quantitative Data from Formative and Summative

Assessments

From the quantitative data presented above there is an indication that GEBL assisted

the students in dealing with larger more complex volumes of work. The students’

performance improved with an increased work load and more complex modules of the

syllabus. There was an improvement in their ability to factual recall of MTHE 2 concepts

as indicated in the Fig. 4.43. This answered the first research question.

197

Factional Knowledge

Line

No.

Test/

Exam

Modules Score %

1

1

0.5

50

2

1b

0.5

48

3

2

2

38

4

3

3

47

5

FE

7

51

Figure 4.43: Students Analytical Performance with an increased workload and with GEBL introduced after Second Assessment

The data also indicated an improvement of the students’ conceptual understanding of

MTHE 2 concepts, principles and applications as indicated in Fig. 4.45. This answered

the second research question. From the oral test data there was indication that GEBL

assisted students in explaining certain concepts and procedures related to MTHE 2 as

indicated in Fig. 4.45. This answered the third research question. The students’

responses gathered from the structured questionnaires were also in support of the data

recorded by the formative and summative assessments. There was an indication that

GEBL assisted them in learning and this was evident from the improvement in

assessment scores.

50 4838

47 51

0

20

40

60

1 2 3 4 5

PE

RC

EN

TA

GE

TESTS 1, 1B, 2, 3 & FINAL EXAMINATION

ANALYTICAL PERFORMANCE WITH

INCREASED WORKLOAD

198

Conceptual Knowledge

Line

No.

Test/

Exam

Modules Score %

1

1

0.5

50

2

1b

0.5

48

3

2

2

38

4

3

3

47

5

FE

7

51

Figure 4.45: Students Analysis Performance with an increased workload and with GEBL introduced after Second Assessment

4.3.5 Addressing the Fourth Research Question

In addressing the fourth research question ‘To what extent would the formulation and

use of key performance indicators (KPIs) be an effective tool for ascertaining students’

attainment of desired educational outcomes in MTHE 2?’; the measurements were

taken with the KPIs and analysed with PASW. These will be discussed to point out the

degree of achievement of the outcomes in each of the assessments performed.

37

34

36

40 40

30

32

34

36

38

40

42

1 2 3 4 5

PE

RC

EN

TA

GE

TESTS 1, 1B, 2, 3 & FINAL EXAMINATION

ANALYSIS PERFORMANCE WITH

INCREASED WORKLOAD

199

Data from KPI Analysis Measurements Test1:

Statistics

ANALYSIS

N Valid 20

Missing 0

Mean 49.600


Median 48.500

Mode 43.0a


Variance 101.200

Skewness .200


Kurtosis -.619


Range 34.0

Minimum 33.0

Maximum 67.0

Sum 992.0


shown

Table 4.31: Quantitative Statistics from KPI Analysis Measurements in Test 1

200

Figure 4.46: Analysis Measurements with KPIs in Test 1

KPIs analysis measurement for Test 1 had a mean of 49.6 and a positive skewness of

0.200. These KPIs measured the ‘Students’ ability to apply MTHE 2 principles to analyse

and solve the problem accurately’ and the ‘Students’ ability to analyse a problem and

produce a solution, taking into account crucial factors in a systematic approach towards

the solution’. The data indicated that the central tendency was about 48.5% with the

score which was most often recorded being 43%. Outcomes were achieved by 49.6%

as a result of traditional teaching and learning approaches. The students’ ability to

acquire conceptual knowledge and understanding and the ability to use this knowledge

201

during problem solving needs to be developed.

Data from KPI Analytical Measurements Test1:

Statistics

ANALYTICAL

N Valid 20

Missing 0

Mean 61.050


Median 63.500

Mode 33.0a


Variance 502.787

Skewness -.123


Kurtosis -1.488


Range 66.0

Minimum 27.0

Maximum 93.0

Sum 1221.0


shown

Table 4.32: Quantitative Statistics from KPI Analytical Measurements in Test 1

202

Figure 4.47: Analytical Measurements with KPIs in Test 1

KPIs analytical measurement of Test 1 had a mean of 61.05 and a negative skewness

of 0.123. These KPIs measured the ‘Students’ ability to apply MTHE 2 principles to

analyse and solve the problem accurately’ and the ‘Students’ ability to analyse a

problem and produce a solution, taking into account crucial factors in a systematic

approach towards the solution’. A few extreme cases were recorded in the upper and

lower percentages. The central tendency was 63.5% which was approximately 2.5%

higher than the mean. However, the score most often recorded was 33%. In this case

the students achieved the outcomes measured by these KPIs by 61.05% with traditional

teaching and learning approaches. The students’ ability to acquire factual and

203

conceptual knowledge and understanding and the ability to use this knowledge during

problem solving was well developed for this low volume of work.

Data from KPI Overall Measurements Test1:

Statistics

OVERALL

N Valid 20

Missing 0

Mean 53.500


Median 51.000

Mode 51.0


Variance 181.316

Skewness .088


Kurtosis -1.186


Range 43.0

Minimum 33.0

Maximum 76.0

Sum 1070.0

Table 4.33: Quantitative Statistics from KPI Performance Measurements in Test 1

204

Figure 4.48: Overall Performance Measurements with KPIs in Test 1

The overall KPI measurement for Test 1 had a mean of 53.5 and a low positive

skewness of 0.088. The central tendency was 51% and the score most often recorded

was also 51%. Therefore, the extent to which the outcomes have been achieved in Test

1 as measured by the KPIs were 53.5% using traditional teaching and learning

approaches on the first half of module 1. The extent to which traditional teaching and

learning assisted the students in acquiring factual and conceptual knowledge and

understanding and the ability to use this knowledge during problem solving needs to be

developed more effectively.

205

Data from KPI Analysis Measurements Test 1b:

Statistics

ANALYSIS

N Valid 20

Missing 0

Mean 47.000


Median 46.000

Mode 43.0


Variance 59.474

Skewness -.171


Kurtosis -.281


Range 29.0

Minimum 31.0

Maximum 60.0

Sum 940.0

Table 4.34: Quantitative Statistics from KPI Analysis Measurements in Test 1b

206

Figure 4.49: Analysis Measurements with KPIs in Test 1b

KPIs analysis measurement for Test 1b had a mean of 47 and a negative skewness of -

0.171. These KPIs measured the ‘Students’ ability to apply MTHE 2 principles to analyse


produce a solution, taking into account the crucial factors in a systematic approach

towards the solution’. The central tendency was 46% and the score which was most

often recorded was 43%. Single cases of outliers were recorded in the upper and lower

percentages and the outcomes which were achieved in Test 1b was 47% with

traditional teaching and learning approaches. The students’ ability to acquire conceptual

knowledge and understanding and the ability to use this knowledge during problem

207

solving needs to be developed.

Data from KPI Analytical Measurements Test 1b:

Statistics

ANALYTICAL

N Valid 20

Missing 0

Mean 57.000


Median 60.000

Mode 65.0


Variance 174.737

Skewness -1.091


Kurtosis 2.469


Range 60.0

Minimum 20.0

Maximum 80.0

Sum 1140.0

Table 4.35: Quantitative Statistics from KPI Analytical Measurements in Test 1b

208

Figure 4.50: Analytical Measurements with KPIs in Test 1b

KPIs analytical measurement for Test 1b had a mean of 57 and a negative skewness of

-1.091. These KPIs measured the ‘Students’ ability to apply MTHE 2 principles to



approach towards the solution’. Isolated cases in the upper and lower percentages were

recorded which pushed the standard deviation up to 13.219. The central tendency was

60% which was 3% lower than the mean as a result of the skewness and the score

most often recorded was 65%. The students’ ability to acquire factual and conceptual

knowledge and understanding and the ability to use this knowledge during problem

209

solving needs to be developed.

Data from KPI Overall Measurements Test 1b:

Statistics

OVERALL

N Valid 20

Missing 0

Mean 50.650


Median 52.000

Mode 49.0a


Variance 78.871

Skewness -.917


Kurtosis 1.808


Range 38.0

Minimum 27.0

Maximum 65.0

Sum 1013.0


shown

Table 4.36: Quantitative Statistics from KPI Overall Performance Measurements in Test 1b

210

Figure 4.51: Overall Performance Measurements with KPIs in Test 1b

The overall KPI measurement for Test 1b had a mean of 50.65 and a negative

skewness of -0.917. The central tendency was 52% with the score which was the most

often recorded being 49%. Isolated cases of outliers pushed the standard deviation up

to 8.881. The extent to which the outcomes have been achieved as measured by the

KPIs in Test 1b was 50.65% with the traditional teaching and learning approach. The

extent to which traditional teaching and learning assisted the students in acquiring

factual and conceptual knowledge and understanding and the ability to use this

knowledge during problem solving resulted in students not being able to achieve most

the selected outcomes on the second half of module one.

211

Data from KPI Analysis Measurements Test 2:

Statistics

ANALYSIS

N Valid 20

Missing 0

Mean 50.100


Median 49.000

Mode 42.0


Variance 105.568

Skewness .100


Kurtosis -.869


Range 38.0

Minimum 31.0

Maximum 69.0

Sum 1002.0

Table 4.37: Quantitative Statistics from KPI Analysis Measurement in Test 2

212



0.1 These KPIs measured the ‘Students’ ability to apply MTHE 2 principles to analyse



the solution’. The central tendency here was 49% and the score most often recorded

was 42%. The degree of achievement of the outcomes was however higher than in

Test 1b which can be contributed to the fact that GEBL did assist student learning and

knowledge retention despite the larger volumes of work. It can also be pointed out that

GEBL assisted the students in developing the ability to deal with more complex work

213

and master it.

Data from KPI Analytical Measurements Test 2:

Statistics

ANALYTICAL

N Valid 20

Missing 0

Mean 52.250


Median 50.000

Mode 60.0


Variance 114.408

Skewness .023


Kurtosis -.926


Range 35.0

Minimum 35.0

Maximum 70.0

Sum 1045.0


214


KPIs analytical measurement for Test 2 had a mean of 52.25 and a small positive

skewness of 0.023. KPIs measured the ‘Students’ ability to apply MTHE 2 principles to



approach towards the solution’. The central tendency in this case was 50% and the

score that was recorded the most often was 60%. The degree of achievement of the

outcomes was however lower than with traditional teaching and learning which can be

215

contributed to the fact that the GEBL intervention took some time before its full effect

was realised and experienced by the students.

Data from KPI Overall Measurements Test 2:

Statistics

OVERALL

N Valid 20

Missing 0

Mean 51.850


Median 50.500

Mode 59.0


Variance 51.503

Skewness -.261


Kurtosis -.706


Range 26.0

Minimum 37.0

Maximum 63.0

Sum 1037.0

Table 4.39: Quantitative Statistics from KPI Overall Performance Measurements in Test 2

216


The overall KPI measurement for Test 2 had a mean of 51.85 and a negative skewness

of -0.261. The central tendency here was 50% with the score that was the most

recorded being 59%. The extent to which the course outcomes for these two modules

have been achieved by GEBL was 51.85%. The average of the first two tests on just

one module was 52.075%. However, although the work load and the degree of

difficulty increased in Test 2, they were able to get 51.85%. Without GEBL this would

not have been possible. 51.85% is lower than the 52.075% which was achieved

through traditional teaching and learning.

217

Data from KPI Analysis Measurements Test 3:

Statistics

ANALYSIS

N Valid 19

Missing 0

Mean 51.632


Median 52.000

Mode 40.0a


Variance 193.357

Skewness .363


Kurtosis .012


Range 53.0

Minimum 31.0

Maximum 84.0

Sum 981.0


Table 4.40: Quantitative Statistics from KPI Analysis Measurements in Test 3

218



0.363. KPIs measured the ‘Students’ ability to apply MTHE 2 principles to analyse and

solve the problem accurately’ and the ‘Students’ ability to analyse a problem and


the solution’. In this case the central tendency was 52% and the score that was

recorded most often was 40%. The outliers at the extreme ends of the scale pushed

the standard deviation up to 13.905. The degree of achievement of the outcomes was

however higher than in Tests 1b and 2, which can be contributed to the fact that GEBL

did assist student learning and knowledge retention despite the larger volumes of work.

219

It can also be pointed out that the students developed the ability to deal with more

complex work and could master it.

Data from KPI Analytical Measurements Test 3:

Statistics

ANALYTICAL

N Valid 19

Missing 0

Mean 58.000


Median 62.000

Mode 62.0


Variance 244.000

Skewness .142


Kurtosis .384


Range 64.0

Minimum 30.0

Maximum 94.0

Sum 1102.0


220


KPIs analytical measurement for Test 3 had a mean of 58 and a positive skewness of

0.142. KPIs measured the ‘Students’ ability to apply MTHE 2 principles to analyse and

solve the problem accurately’ and the ‘Students’ ability to analyse a problem and


the solution’. The central tendency in this case was 62% with the score recorded most

often also being 62%. The low number outliers on the scale pushed the standard

deviation up to 15.62. The degree of achievement of the outcomes was however higher

than in Tests 1b and 2 which can be contributed to the fact that GEBL did assist student

221

learning and knowledge retention despite the larger volumes of work. It can also be

pointed out that the students developed the ability to deal with more complex work and

could master it.

Data from KPI Overall Measurements Test 3:

Statistics

OVERALL

N Valid 19

Missing 0

Mean 53.842


Median 56.000

Mode 50.0a


Variance 175.363

Skewness -.107


Kurtosis -.468


Range 47.0

Minimum 32.0

Maximum 79.0

Sum 1023.0


shown

Table 4.42: Quantitative Statistics from KPI Overall Performance Measurements in Test 3

222


The overall KPI measurement for Test 3 had a mean of 53.84 and a negative skewness

of -0.107. The central tendency in this case was 56% and the score recorded most

often was 50%. The outliers in this case pushed the standard deviation up to 13.242.

The extent to which the outcomes have been achieved in Test 3 as measured by the

KPIs was 53.84% which is an improvement from the 51.85% in Test 2. Again attention

must be drawn here to the fact that Test 3 was written on three modules which were

more complex than module 1 for Tests 1 and 1b and more complex than the two

modules for Test 2. The degree of achievement of the outcomes was however higher

than in Tests 1b and 2 which can be contributed to the fact that GEBL did assist student

223

learning and knowledge retention despite the larger volumes of work. It can also be

pointed out that the students developed the ability to deal with more complex work and

could master it.

Data from KPI Analysis Measurements Final Examination:

Statistics

ANALYSIS

N Valid 15

Missing 0

Mean 52.467


Median 53.000

Mode 60.0


Variance 169.981

Skewness -.081


Kurtosis .657


Range 51.0

Minimum 29.0

Maximum 80.0

Sum 787.0

Table 4.43: Quantitative Statistics from KPI Analysis Measurements in the Final Examination

224

Figure 4.58: Analysis Measurements with KPIs in the Final Examination

KPIs analysis measurement for the final examination had a mean of 52.47 and a

negative skewness of -0.81. KPIs measured the ‘Students’ ability to apply MTHE 2

principles to analyse and solve the problem accurately’ and the ‘Students’ ability to

analyse a problem and produce a solution, taking into account crucial factors in a

systematic approach towards the solution’. The central tendency here was 53% and the

score that most often recorded was 60%. The low number outliers pushed the standard

deviation up to 13.038. The degree of achievement of the outcomes was however

higher than that of all the previous assessments, which can be contributed to the fact

that GEBL did assist student learning and knowledge retention despite the larger

225

volumes of work. It can also be pointed out that the students developed the ability to

deal with more complex work and could master it

Data from KPI Analytical Measurements Final Examination:

Statistics

ANALYTICAL

N Valid 15

Missing 0

Mean 59.600


Median 59.000

Mode 58.0a


Variance 179.400

Skewness -.997


Kurtosis 3.094


Range 59.0

Minimum 24.0

Maximum 83.0

Sum 894.0


shown

Table 4.44: Quantitative Statistics from KPI Analytical Measurements in the Final Examination

226

Figure 4.59: Analytical Measurements with KPIs in the Final Examination

KPIs analytical measurement for the final examination had a mean of 59.6 and a

negative skewness of -0.997. KPIs measured the ‘Students’ ability to apply MTHE 2

principles to analyse and solve the problem accurately’ and the ‘Students’ ability to

analyse a problem and produce a solution, taking into account crucial factors in a

systematic approach towards the solution’. The central tendency here was 59% and the

score that was recorded most often was 58%. The low number of outliers pushed the

standard deviation up to 13.394. The degree of achievement of the outcomes was

however higher than Tests 1b, 2 and 3, which can be contributed to the fact that GEBL

did assist student learning and knowledge retention despite the larger volumes of work.

227

It can also be pointed out that the students developed the ability to deal with more

complex work and could master it

Data from KPI Overall Measurements Final Examination:

Statistics

OVERALL

N Valid 15

Missing 0

Mean 56.867


Median 58.000

Mode 58.0a


Variance 124.838

Skewness -.504


Kurtosis .353


Range 43.0

Minimum 33.0

Maximum 76.0

Sum 853.0


shown

Table 4.45: Quantitative Statistics from KPI Overall Performance Measurements in the Final Examination

228

Figure 4.60: Overall Performance Measurements with KPIs in the Final Examination

The overall KPI measurement for the final examination had a mean of 56.867 and a

negative skewness of -0.504. The central tendency in this case was 58% and the score

recorded most often was also 58%. The low number of outliers on the extreme end of

the scale pushed the standard deviation up to 11.1731. The extent to which the

outcomes for MTHE 2 have been achieved as measured with the KPIs was 56.867%.

This is a significant improvement from the previous tests and what made it even more

significant was the fact the final examination was on seven modules (progressively

more difficult and a larger volume of work) which was covered over a period of 13

229

weeks. Here it was quite evident that GEBL made the lecturing process a more effective

one looking at the above results. Even with a larger volume of work with increased

complexities, the higher was the degree of achievement.

Results obtained from the KPIs for the formative as well as summative

assessments:

KPIs

Percentage

Assessment Analysis Analytical Overall

Test 1 49.6 61.05 53.5

Test 1b 47 57 50.65

Test 2 50.1 52.25 51.85

Test 3 51.63 58 53.84

Final examination 52.47 59.6 56.87

Total 50.16 57.58 53.34

Table 4.46: Summary of results from KPI Measurements of Tests 1, 1b, 2, 3 and Final Examination

4.3.6 Summary of Data from KPIs for Tests 1, 1b, 2, 3, and Final Examination

50.16% of the analysis component as defined in the course outcomes for MTHE 2 had

been achieved as indicated in Table 4.46. It also showed that the students’ ability to

analyse problems improved from an average of 48.3% in the first module (traditional

teaching) to an average of 51.4% in the modules offered with GEBL.

57.58% of the analytical component of MTHE 2 outcomes has been achieved as

230

indicated in Table 4.46. It showed that the students’ ability to perform analytical

procedures on one module of the syllabus was 59.03% on one module covered with

traditional teaching and their ability to perform analytical procedure was an average of

56.62% on 2, 3 and 7 modules covered with GEBL.

The first module’s outcomes were 52.08% and that of the GEBL modules was 54.19%

as indicated in Table 4.46. These results indicated that the GEBL intervention had a

50.16% success rate in developing the students’ ability to analyse problems. There was

a 57.58% success rate in terms of students’ ability in developing an analytical solution

to a particular problem. The overall achievement of course outcomes measure by KPIs

‘1’ and ‘4’ was 53.34%. The KPIs achievements of the selected course outcomes are

indicated in Fig. 4.61.

KPI Achievement with GEBL

Line Number Number of modules

Score %

1

0.5

55

2

0.5

52

3

2

52

4

3

54

5

7

57

Figure 4.61: Overall KPI Achievement with an increased workload, with GEBL being introduced after the Second Assessment

49

50

51

52

53

54

55

56

57

58

T1 T1b T2 T3 FE

Pe

rce

nta

ge

s

KPIs Percentage Achievements

231

Data from KPI Explanation Measurements Oral Tests 1 and 2:

Statistics

EXPLANATION

N Valid 15

Missing 0

Mean 54.6667


Median 60.0000

Mode 20.00a


Variance 412.381

Skewness -.808


Kurtosis -.323


Range 60.00

Minimum 20.00

Maximum 80.00

Sum 820.00


shown

Table 4.47: Quantitative Statistics from KPI Explanation Measurements in Oral Tests 1 and 2

232

Figure 4.62: Explanation Measurements with KPIs in Oral Tests 1 and 2

The KPI explanation measurement for oral Tests 1 and 2 had a mean of 54.67 and a

negative skewness of -0.808. KPIs measured the ‘Students’ ability to explain/discuss;

the operation of a system, components or parts of a system in MTHE 2, components

function in the overall plant which it forms part of, treatment and maintenance

procedures in specific components’ and the ‘Students’ ability to perform technical

discussions on MTHE 2 topics, communicates fluently, explains and demonstrates

concepts effectively in MTHE 2’. The outliers in the lower percentages pushed the

standard deviation up to 20.307. The central tendency in this case was 60% and the

scored most often recorded was about 20%. GEBL assisted the students in developing

233

the ability to explain concepts and procedures related to MTHE 2 accurately.

Data from KPI Understanding Measurements Oral Tests 1 and 2:

Statistics

UNDERSTANDING

N Valid 15

Missing 0

Mean 50.6667


Median 55.0000

Mode 20.00a


Variance 356.667

Skewness -.394


Kurtosis -.074


Range 65.00

Minimum 20.00

Maximum 85.00

Sum 760.00


shown

Table 4.48: Quantitative Statistics from KPI Understanding Measurements in Oral Tests 1 and 2

234

Figure 4.63: Understanding Measurements with KPIs in Oral Tests 1 and 2

The KPIs understanding measurement for Oral Tests 1 and 2 had a mean of 50.67 and

negative skewness of -0.394. KPIs measured the ‘Students’ ability to explain/discuss;

the operation of a system, components or parts of a system in MTHE 2, components


procedures in specific components’ and the ‘Students’ ability to perform technical

discussions on MTHE 2 topics, communicates fluently, explains and demonstrates

concepts effectively in MTHE 2’. The outliers in the upper and lower percentages

pushed the standard deviation up to 18.886. The central tendency in this case was 55%

and the score most often recorded was 20%. GEBL assisted the students in

235

understanding MTHE 2 concepts, processes and procedures by expressing it in their

own words.

Data from KPI Discussion Measurements Oral Tests 1 and 2:

Statistics

DISCUSSION

N Valid 15

Missing 0

Mean 68.6000


Median 71.0000

Mode 71.00a


Variance 269.114

Skewness -.614


Kurtosis .011


Range 55.00

Minimum 36.00

Maximum 91.00

Sum 1029.00


shown

Table 4.49: Quantitative Statistics from KPI Discussion Measurements in Oral Tests 1 and 2

236

Figure 4.64: Discussion Measurements with KPIs in Oral Tests 1 and 2

The KPI discussion measurement for Oral Tests 1 and 2 had a mean of 68.6 and a

negative skewness of -0.614. KPIs measured the ‘Students’ ability to explain/discuss the

operation of a system, components or parts of a system in MTHE 2, components


procedures in specific components and the ‘Students’ ability to perform technical

discussions on MTHE 2 topics, communicate fluently, explain and demonstrate concepts

effectively in MTHE 2’. The central tendency in this case was 71% and the score most

often recorded was also 71%. GEBL assisted the students develop the ability to perform

technical discussions effectively.

237

Data from KPI Overall Measurements Oral Tests 1 and 2:

Statistics

OVERALL

N Valid 15

Missing 0

Mean 57.9333


Median 64.0000

Mode 69.00


Variance 183.924

Skewness -.906


Kurtosis .012


Range 46.00

Minimum 28.00

Maximum 74.00

Sum 869.00

Table 4.50: Quantitative Statistics from KPI Overall Performance Measurements in Oral Tests 1 and 2

238

Figure 4.65: Overall Performance Measurements with KPIs in Oral Tests 1 and 2

The overall KPI measurement for Oral Tests 1 and 2 had a mean of 57.93 and a

negative skewness of -0.906. The central tendency in this case was 64% and the score

most often recorded was 69%. The low number of outliers in the lower percentages

pushed the standard deviation up to 13.562. The extent to which the outcomes of

MTHE 2 have been achieved as measured by the KPIs was 57.93%. This was the first

time that oral assessments on the entire syllabus were done in MTHE 2 and also the

first time that the KPI measurement was used. The data showed that the students

achieved the outcomes by demonstrating their ability as stipulated in the KPIs in

explaining, understanding and discussing various topics of the syllabus satisfactorily.

239

Future studies can be done to compare the difference in achievement of the course

outcomes by means of the traditional teaching and learning methods and GEBL.

Results obtained from Oral Tests 1 and 2 were as follow:

KPIs

Percentage

Assessment Explanation Understanding Discussion Overall

Oral Tests 1 and 2

55 51 69 58

Table 4.51: Summary of results from KPI Measurements in Oral Tests 1 and 2

Reliability statistics for KPIs:

Reliability Statistics

Cronbach's

Alpha

Cronbach's

Alpha Based on

Standardized

Items N of Items

.801 .818 10

Table 4.52: Quantitative Statistics for reliability from KPI Measurements in Oral Tests 1 and 2

The Cronbach’s Alpha test for internal consistency of the instruments gave a score of

0.80 for the KPIs. The Cronbach’s Alpha reliability coefficient ranges from 0 to 1.

The closer the value of alpha is to 1.0 the greater the internal consistency of the

instruments.

240

4.3.7 Summary of Data from KPIs for Oral Tests 1 and 2

55% of the students could give a satisfactory explanation of the questions posed to

them. This also indicated that these students could express themselves properly and

could use the correct terms during explanations (see table 4.51).

51% of the students understood the questions posed to them. They could make a

connection between the theory and what happened in practice of what was being

asked. These students understood how the plant operated, what the function of each

component was and how the one component affected the other. They also knew which

factors could influence the overall operation and with regard to safety which reading

should be monitored closely (see table 4.51).

69% of the students were able to perform discussions on various issues and could

express themselves satisfactory. Here the students were able to discuss operations,

processes and procedures satisfactory (see table 4.51).

KPIs ‘2’ and ‘3’ were used to measure the extent to which the relevant outcomes were

achieved, which was 58% as indicated in table 4.51.

241

4.4 Summary of Highest Scored Data

4.4.1 Theory Questions from Written Assessments

From the data collected, a summary of the highest scored theory questions are given

below.

Test 2 (see Appendix 5)

Question 2.3

“Explain the steps to be followed to calculate all that is required to do an analysis”.


Question 4.1

“Draw a detailed flow diagram of the Rankine cycle”.

Final Examination (see Appendix 8)

Question 4.1 (T7)

“Complete the attached diagram/s, indicate clearly the wet and dry air pump units and

fill in all relevant detail as well as the directions of flow for the air, water and steam”.

In the questions listed above, students had achieved scores of 77%, 73% and 65%,

respectively. Here they demonstrated a clear understanding of the problem presented

to them as well as the ability to analyse the information provided in the problem. The

majority were also able to use that information to accurately address the questions

242

posed, which shows a high level of conceptual knowledge. The students were also able

to link the theory of processes with diagrams successfully (see tables 4.9, 4.12 & 4.15).

4.4.2 Structured Questionnaire (see Appendix 1)

Student responses to the following questions:

Questions Strongly agree

Agree Neutral Disagree Strongly disagree

4. This method helped me to understand the work and not to just memorise it.

66.7%

26.7%

6.7%

0%

0%

5. This method helped me develop the ability to solve problems on my own.

26.7%

66.7%

6.7%

0%

0%

1. 7. The Thermodynamics booklets’ additional questions and answers helped me to understand and analyse new problems better.

26.7%

60%

13.3%

0%

0%

4.4.3 Interviews (see Appendices 2 & 13):

Item 1a: The group sessions motivated you to come prepared to class.

Positive responses: So that I can work together and not be left behind/I will have to explain what I understand/it was like a competition and nobody wants to look stupid 18 (N = 18)

Neutral or negative responses: Group sessions did not motivate me to come prepared to class 0 (N = 18)

Item 1b: The group sessions helped developing your communication skills.

Positive responses: In the group you use English so you become use to the language/I can explain to others and we can share/because I have to talk to others and on my own I do not communicate 18 (N = 19)

Neutral or negative responses: It was difficult to take part in the group sessions because I am a shy person 1 (N = 19)

Item 4: This method helped me to understand the work and not to just memorise it.

Positive responses: We share information and analyse the problem so we understood what to do/group discussions helped us to understand the work/we were able to use questions to analyse new problems 20 (N = 20)

Neutral or negative responses: This method did not help me to understand the work and I still have to memorise it 0 (N = 20)

Student A

“... not just knowing what you calculate but what is it in the engineering field what

significance does it have...”

243

Student C

“... this method gives us the ability to understand it and not just guessing or

memorizing it... You know in discussions you would go through in groups, debates

and we are challenging each other in the groups someone gets to be disagreeing

with you in the group and you will have to try to convince and explain to him

exactly how you really view this...”

Student I


4.4.4 Oral Test 1 (see Appendix 7)

Question 7

“Explain which components constitute the steady flow energy equation”.

Question 11

“Which products of combustion appear in the table for a mass analysis?”

Oral Test 2 (see Appendix 7)

Question 3

“What are the differences between the following processes: adiabatic, polytropic and

isothermal?”

In the questions listed above the students had achieved scores of 91.4%, 91.4% and

244

100%, respectively. The students were able to give clear and accurate explanations.

They also had a good understanding of the process/processes involved and could list

the differences clearly (see tables 4.19 & 4.20).



Positive responses: In the group you use English so you become use to the language/I can explain to others and we can share/because I have to talk to others and on my own I do not communicate 18 (N = 19)

Neutral or negative responses: It was difficult to take part in the group sessions because I am a shy person 1 (N = 19)

Item 2: The enquiry based sessions helped me to analyse problems effectively.

Positive responses: The questions given help me to analyse the problems/I have to ask myself what do I understand about the problem/we were taught how to tackle problems and how to get answers to our questions/when I work on my own I try to ask myself questions about what is given and what do I understand about the problem 20 (N = 20)

Neutral or negative responses: The enquiry based sessions did not help me to analyse problems more effectively 0 (N = 20)


Positive responses: We share information and analyse the problem so we understood what to do/group discussions helped us to understand the work/we were able to use questions to analyse new problems 20 (N = 20)

Neutral or negative responses: This method did not help me to understand the work and I still have to memorise it 0 (N = 20)

Student responses from interviews regarding GEBL and in particular its influence on

communication, the ability of students to express themselves and to interact:

Student B

“In Thermodynamics there are a number of terms and well just terms you need to

know that you don’t really pick up if you do work without talking about the work.

So the fact that you were talking about the work helped you to understand these

terms and in turn helped you understand more Thermodynamics”.

245

Student K


explaining what is happening...’’

Student L

“I think in this method you gain a lot of skill other than solving the problem, first

you get a chance to communicate and be motivated to be not shy in class... you

gain other skills other than solving problems like talking in front of the people...”

4.4.6 Calculation Questions from Written Assessments


Question 2.4

“Perform the calculations as explained in 2.3”.


Question 3.3

“Determine the degree of dryness in the main supply line”.

Final Examination (see Appendix 8)

Question 2.2 (C5)

“Determine the work done by the steam during the heating process”.

246

In the questions listed above, the students had achieved scores of 84.15%, 89.42%

and 89.27%, respectively. The students were able to manipulate and use the

information supplied in the problem to determine the required solution. It shows that

they understood the relationship between the information presented (variables supplied

in problems) as well as the particular process involved and how to work systematically

to find a solution (see tables 4.10, 4.13 & 4.16).

4.4.7 Structured Questionnaire (see Appendix 1)

Questions Strongly agree

Agree Neutral Disagree Strongly disagree

2. The enquiry based sessions helped me to analyse problems effectively.

73.7%

26.7%

0%

0%

0%

3. When working alone the enquiry based approach helped me to analyse problems effectively.

33.3%

26.7%

40%

0%

0%


26.7%

66.7%

6.7%

0%

0%

247



Positive responses: The questions given help me to analyse the problems/I have to ask myself what do I understand about the problem/we were taught how to tackle problems and how to get answers to our questions/when I work on my own I try to ask myself questions about what is given and what do I understand about the problem 20 (N = 20)

Neutral or negative responses: The enquiry based sessions did not help me to analyse problems more effectively 0 (N = 20)

Item 3: When working alone the enquiry based approach helped me to analyse problems effectively.

Positive responses: I used the information which I have learned during the group sessions/I follow the same approach in analysing the question that we have used in group sessions/I asked myself similar questions to those that we have asked during group sessions, when working alone 20 (N = 20)

Neutral or negative responses: The enquiry bases approach did not help me to solve problems when working alone 0 (N = 20)

Item 5: This method helped me develop the ability to solve problems on my own.

Positive responses: When alone use the same approach that have been used during group sessions, analyse the new problem by asking questions/you have many methods of approaching the problem and how to ask questions that leads you to ways to solve the problem/asking question gives me more information about a problem 20 (N = 20)

Neutral or negative responses: This method did not help me to develop the ability or to improve my ability to solve problems 0 (N = 20)

Item 6: The Thermodynamics booklet with questions and answer helped me to understand the work better.

Positive responses: The layout and explanations in the booklet helped us to understand new work better/

Neutral or negative responses: The Thermodynamics booklet did not help to understand the work better 0 (N =20)

Item 7: The Thermodynamics booklet’s additional questions and answers helped me to understand and analyse new problems better.

Positive responses: The additional questions in the booklet assisted us to analyse new problems/the additional questions helped me to gain more information about the problem 4 (N = 4)

Neutral or negative responses: The booklet with the additional questions and answers did not help to understand and analyse new problems better 0 (N = 4)

Student A

“... I am in a position to analyse the question and to manipulate whatever it is that

I have...”

248

Student C

“We were encouraged to write down a certain sequence of each question and how

to answer the question and we were given time before each problem to evaluate

how we were going to actually answer the question, not just looking at the

question and trying to answer that specific question, cause you have to find a

number of things before you answer the actual question that’s asked... before we

actually tackle the problem we would have a list of certain questions that we ask

to ourselves”.

Student J



4.5 Summary

From the data presented there are several significant findings.

Firstly, GEBL assisted the students in factual recall of MTHE 2 concepts. There was

evidence that students’ performance increased with an increased work load. These

were supported by the data from the structured questionnaires as well as the interview

responses (see subsections 4.3.3, 4.4.2 & 4.4.3).

Secondly, GEBL assisted the students in understanding MTHE 2 concepts, principles and

249

applications. Students were also able to learn new material, understand it and apply

this knowledge in solving problems. These were also supported by the data from the

structured questionnaires and the students’ responses to the interviews (see

subsections 4.3.3, 4.4.2 & 4.4.3).

Thirdly, GEBL assisted the students in their communication skills and the use of MTHE 2

terms. Students were also able to explain concepts, processes and procedures

accurately as indicated in assessment scores (see subsections 4.3.3, 4.4.2 & 4.4.5).

250

CHAPTER 5

DISCUSSION OF FINDINGS, CONCLUSION AND RECOMMENDATIONS

This chapter discusses and highlights the findings from the data collected in chapter 4.

Both qualitative and quantitative finding are discussed in relation to the literature

reviewed and the research questions and objectives. The performance of the students

during these assessments as well as their interview responses are also compared to

determine whether there was a correlation between the quantitative and qualitative

data. These findings are then compared with what is reported in literature.

The discussion first concentrates on how the students performed in the theoretical

components of the assessments. Secondly their performances in the questions where

they had to perform certain calculations are discussed. Finally the achievements of the

KPIs will be discussed.

A conclusion will also be made on how the findings from this study addressed the aim

and objectives of this research study and how these findings are congruent with those

from similar studies. This chapter will then be concluded by recommendations and a

proposed future model for presenting MTHE 2 and mechanical engineering courses in

general.

251

5.1 GEBLs Impact on Student Performance

Discussions with regard to the findings will now be made in an attempt to address the

research questions.

5.1.1 High Scores - Written Theory Assessments

In addressing the first and second research question: ‘What would be the effect of a

guided enquiry-based learning (GEBL) approach on mechanical engineering students’



understanding of MTHE 2 concepts, principles and applications?’ the mean values from

the following tables will be considered:

Table 4.9: Question T2.3 mean 77%;

Table 4.12: Question T4.1 mean 73.053%;

Table 4.18: Question T7 mean 65.133%.

Students’ responses on how GEBL assisted their learning:

“... this method gives us the ability to understand it and not just guessing or

memorizing it...”

252

“... not just knowing what you calculate but what is it in the engineering field

what significance does it have...”

From the structured questionnaire item ‘This method helped me to understand the work

and not to just memorise it’, 66.7% of the students strongly agreed and from the item

‘This method helped me develop the ability to solve problems on my own’ 26.7%

strongly agreed and 66.7% agreed.

With regard to the above results and responses: These results suggested that the

students gave satisfactory answers to the various questions. They were also able to

recall factual knowledge and demonstrate understanding of conceptual knowledge.

These performances are also supported by the students’ interview responses. Similar

findings where students had to recall facts, explain processes and procedures are

consistent with those from other studies done on active learning in engineering

education (Prince, 2004; Felder & Brent, 2003; Spronken-Smith, 2007). Findings from

studies done on Kolb’s learning cycle as pedagogy for teaching students in engineering

to address different learning styles, are similar and in support of those found by this

study (Ogot & Okudan, 2006; Kapranos, 2007; Aziz & Chassapis, 2008; Altuger et al.,

2009; Stappenbelt, 2010; Elshorbagy & Schonwetter, 2002). The process followed with

GEBL i.e. introducing new concepts and principles; performing a class example

engaging students during question formulation; group sessions with interaction

between group members and group members and lecturer; feedback on group

253

approaches and progress; individual homework and problem solving, allowed for

students with different learning styles to be catered for by one or more of the stages of

GEBL approach. It has different learning approaches which cater for a larger spectrum

of learning styles which is not the case with the traditional teaching and learning

method. This resulted in the increase of the class average from 46% to 55%. The

above observations are also supported by researchers who investigated the impact of

learning styles on student performance (Goldfinch et al., 2008; Kapadia, 2008;

Lamancusa et al., 2008; Naher et al., 2008; O’Dwyer, 2008). GEBL has also resulted in

an effective teaching strategy of MTHE 2. GEBL as an effective teaching strategy is

supported by Killen (2006, p.3). Findings from this study that GEBL also assists deep

learning which resulted in higher retention rates are in line with those from other

studies done on deep learning in engineering education (Ying, 2003; Fowler, 2004;

Qualters et al., 2008; Felder & Brent, 2010).

5.1.2 High Scores - Written Calculation Assessments

In addressing the first and second research question: ‘What would be the effect of a

guided enquiry-based learning (GEBL) approach on mechanical engineering students’



understanding of MTHE 2 concepts, principles and applications?’ the mean values from

the following tables will be considered:

254

Table 4.10: Question C2.4 mean 84.15%;

Table 4.13: Question C3.3 mean 89.421%;

Table 4.19: Question C5 mean 89.267%.

Students’ responses on how GEBL assisted them when they had to solve problems:

“... I am in a position to analyse the question and to manipulate whatever it is

that I have...”

“... before we actually tackle the problem we would have a list of certain

questions that we ask to ourselves”.



From the structured questionnaire item ‘The enquiry based sessions helped me to

analyse problems effectively’, 73.7% of the students strongly agreed and from item

‘This method helped me develop the ability to solve problems on my own’, 26.7% of the

students strongly agreed and 66.7% agreed.

With regard to the above results and responses: GEBL gave the students a departure

point when they were facing new problems. This view is also expressed by the students

255

during the interviews. It assisted them to start the analysis process which helped them

to understand the process involved and what variables were given and also what the

relationships between those variables were. GEBL also sought to develop students’

ability to manipulate information supplied in questions and to approach a particular

problem from different angles in order to find a solution. Here, the students used

critical thinking skills to achieve their goal. Studies done on the importance of Bloom’s

taxonomy for the development of critical thinking skills and the achievement of learning

outcomes in engineering education (Boles et al., 2005, p.3) are in agreement with the

findings, presented above, from this study. The results from the tables 4.10, 4.13 and

4.19 suggest that GEBL assists deep learning which, results in effective problem solving

abilities. Similar views are corroborated by researchers who have done studies on deep

learning in engineering education (Robbins & Ardebili, 2006, p.6). GEBL also assisted in

the achievement of significant learning to a certain degree, by guiding students through

a number of steps which they had to follow when solving problems. This corresponds

with the ‘learn how to learn’ described in Finks taxonomy of significant learning (Fink,

2003, pp.4-6). GEBL promoted the movement through Kolb’s learning circle which

resulted in students retaining information for longer periods of time and being able to

apply it in different problem-solving situations. This view is supported by Elshorgaby et

al., (2002, p.297).

5.1.2.1 Factual Knowledge

There was an improvement in the students’ ability to use factual knowledge (formulas,

256

relationships between variables) as indicated in Fig. 4.62. It also indicated that students

were more competent in using their background knowledge and experience gained

through the group sessions to analyse and solve new problems which suggested that

they had achieved deeper learning. These findings are in line with similar studies on

deep learning approaches (Ying, 2003; Fowler, 2004). Results found by this study

correspond well with findings from studies done on active learning approaches which

showed an improvement in student learning (Junglas, 2006; Fuehne, 2007). This

suggested that a GEBL approach of learning new material by means of interactions,

group discussions, sharing ideas and interpretations and using systematic enquiry-

based approaches to solving new problems as showed by the evidences provided by

this study improved students learning.

5.1.2.2 Conceptual Knowledge

Correct understanding of concepts form building blocks of principles and relationships.

With regard to the theoretical part of the course where students had to understand new

theories, processes, principles and relationships the enquiry-based approach also

assisted in the improvement of the students’ knowledge retention ability. This can be as

a result of the way in which the students encountered new information and how the

new information was discussed and shared which made their understanding of the new

information more effective. From the scores in Fig. 4.63 it is quite evident that GEBL

helped the students in understanding new concepts, theories and enabled them to

analyse problems effectively so that they understood the process/processes involved

257

and were able to reflect these process/processes on diagrams accurately. GEBL also

improved the students’ ability to deal with larger complex volumes of work successfully.

These results are in line with findings from other studies that active student-centred

learning improve students’ knowledge retention, the development of (higher) order

thinking skills, group work, problem solving, the formulation of good questions,

analysing problems and developing solutions (see for example, Lee, 2004; Prince, 2004;

Prince & Felder, 2006; Huet et al., 2007; Ma, 2009).

5.1.3 High Scores - Oral Assessments

In addressing the third research question: ‘What would be the effect of a guided

enquiry-based learning (GEBL) approach on mechanical engineering students’ ability to

communicate procedures and processes related to MTHE 2?’ the mean values from the

following tables will be considered:

Table 4.15: Question T7 mean 91.42%, Question T11 mean 91.42%;

Table 4.16: Question T3 mean 100%.

258

Students’ responses to the influence of GEBL on communication skills:

“In Thermodynamics there are a number of terms and well just terms you need

to know that you don’t really pick up if you do work without talking about the

work. So the fact that you were talking about the work helped you to understand

these terms and in turn helped you understand more Thermodynamics”.


explaining what is happening...’’

With regard to the above results and responses: During the Oral tests the majority of

the students could give a satisfactory answer to many of the questions, thereby

showing a high level of conceptual knowledge on relevant sections of the work.

Students who were normally shy and not confident in using Thermodynamic terms

could express themselves and actively participate in technical discussions. Other studies

done on the impact of active learning in engineering education also found that it

enhanced student interaction and assisted technical communication. This view is

corroborated by many researchers in the field (Weck, 2003; Zubair & Antar, 2004;

Charelvoix, 2008).

5.2 KPI Achievement with GEBL

In addressing the fourth research question: ‘To what extent would the formulation and

259

use of key performance indicators (KPIs) be an effective tool for ascertaining students’

attainment of desired educational outcomes in MTHE 2?’ the mean values from the

following tables will be considered:

Table 4.33 Test 1 mean 53.5%;

Table 4.36 Test 1b mean 50.65%;



Table 4.45 Final Examination mean 56.867%;

Table 4.50 Oral Tests 1 and 2 mean 57.9333%;

With regard to the above results: The data collected from these KPI measurements

indicated a drop in achievement of outcomes from Test 1 to Test 1b with the traditional

lecturing approach as indicated in Fig. 4.64. The GEBL was introduced after Test 1b and

there was an improvement in achieving the outcomes from 50.65% to 51.85%. These

scores progressively improved over the remainder of the modules. There was no control

group in this study, so a comparison with traditional teaching and learning outcomes

could not be made. However these findings gave an indication of the extent to which

the outcomes of MTHE 2 had been achieved in the respective modules. Follow-up

studies can use these KPIs in a control/experimental group design to determine the

effectiveness of GEBL compared to the traditional approach of teaching and learning.

This however, lies outside the scope of this research.

260

5.3 Conclusion

From the qualitative and quantitative data collected in this study and the data

presented by similar studies the following conclusions can be made:

In this study active learning had a positive impact on student learning and the

introduction of GEBL in MTHE 2 resulted in a fruitful experience with the improvement

of overall scores. It was found that when students were more actively involved in the

learning process, they learned new concepts easier than what was in the past and

understood the work better. All types of presented data show these factors. Similar

views are corroborated by other researchers (Lee, 2004; Prince, 2004; Fuehne, 2007).

The students were also able to apply the information in new situations. This in turn

resulted in an improved academic performance. GEBL also exposed the students more

often to situations which required them to communicate and to use MTHE 2 terms

compared to the traditional teaching and learning approach as transcriptions of

interview data in particular point to. This also assisted them in developing

communication skills. The assistance that active learning had on the improvement of

communication skills are supported also by other researchers in the field (De Weck et

al., 2003; Zubair & Antar, 2004).

From the twenty students in the GEBL group, 75% qualified for the final examination.

80% of those who wrote the final examination passed which resulted in 60% of the

original GEBL group who passed the course overall. The average pass rate for this

261

course with traditional teaching method was below 40% which indicated a significant

improvement in student performance with GEBL.

The KPIs that were developed can be used for future measurements of the

achievement of MTHE 2 course outcomes and will give an indication of the effectiveness

of the teaching and learning method used in terms of achieving the specified outcomes.

These KPIs can also be used for the other mechanical engineering courses which have

similar outcomes to that of MTHE 2.

In conclusion, it is clear that GEBL improved student learning and the development of

professional skills in this study. However the degree to which this approach is more

effective than the traditional practices can only be determined through comparative

studies in future although the 60% pass of GEBL students when compared to 40% pass

for traditional method students show the better effectiveness of GEBL. There was also

sufficient evidence that GEBL improved students’ factual recall of thermodynamics

concepts; students’ conceptual understanding of thermodynamics concepts, principles

and applications; and students’ ability to communicate procedures and processes

related to thermodynamics. The measurements obtained from the KPIs gave feedback

to the researcher regarding the effectiveness of GEBL in achieving the specified

outcomes in each section of the syllabus of MTHE 2. This can be used for future

improvement of teaching and learning methods. In summary, the aim and objectives

stated for this study have therefore been successfully achieved.

262

5.4 Recommendations

Recommendations resulting from the findings of this study are as follows:

Lecturers need to pay more attention to the atmosphere which is created in the

classrooms. Students need to feel being welcomed and comfortable during a lecturing

session. Attention must be paid to the relationship between the lecturer and the

students. Although this should remain professional, the atmosphere created must allow

students to feel free to approach the lecturer. Lecturing venues should also be

equipped with re-groupable standing desks and chairs to allow for group work.

Suggested future presentations of MTHE 2:

The lecturer supplies the students with GEBL notes prior to the commencement

of the lecture. The lecturer introduces new concepts, principles and theories in

MTHE 2 to students. Students listen and take the necessary notes. This part of

the lecture must be minimised to allow for maximum interaction from students;

The lecturer does an example with the whole class following the EBL approach.

Students are involved by formulating questions to analyse the example;

The students are randomly divided into groups to avoid clicks to be formed

within any group. The students are then presented with a new problem to solve.

They work in groups and are given a few minutes to formulate the three to five

most relevant questions pertaining to the problem. This can be done by selecting

questions from the GEBL notes, formulating questions, interacting and discussing

all the detail needed to understand the process or processes involved.

The lecturer stops the whole class to get feedback from each group regarding

263

the questions they have formulated. Any irrelevant question or problems are

dealt with.

The students then use the information gathered from the questions and

discussions to develop a solution to the problem within a specified time. The

lecturer moves between the groups and assists individuals or groups with

problems.

At the end of the time feedback is given from each group and problems are dealt

with. The process is repeated until the lecture comes to ends.

Students are given homework to do for the next lecture and the lecturer

motivate them to do the homework and also needs to check and ensure that

they do the work as assigned.

The models (see subsections 5.5 & 5.6 that follow) proposed below and the

Appendices, especially Appendix 12 will help to implement GEBL effectively and

efficiently.

264

5.5 Proposed Louw’s Model for Thermodynamics 2

Student

group interaction

Introduction to basic


theories in MTHE 2

Lecturer

Student 1

Do an example with class

applying GEBL principles

Student 5 Student 4

Student 3

Student 2

Present groups with

new problems to solve

using GEBL approach

Students listen and

take notes

Students take part

in formulating

questions to

analyse problem

1

1

2

3

2

3

Students work in groups and lecturer acts as facilitator

265

5.6 General Model

From the above model, a possible pragmatic general model can be implemented in an

inductive approach. Lecturers must pay attention to the time that they spend on

lecturing. This time must be kept to a minimum to allow more time for group-work.

Suggested future presentations of mechanical engineering courses (see the general

model below):

The lecturer supplies the students with GEBL notes prior to the commencement

of the lecture. The lecturer introduces new concepts, principles and theories in

the particular course to students. Students listen and take the necessary notes.

This part of the lecture must be minimised to allow for maximum interaction

from students;

The lecturer does an example with the whole class following the EBL approach.

Students are involved by formulating questions to analyse the example;

The students are randomly divided into groups to avoid clicks to be formed

within any group. The students are then presented with a new problem to solve.

They work in groups and are given a few minutes to formulate the three to five

most relevant questions pertaining to the problem. This can be done by selecting

questions from the GEBL notes, formulating questions, interacting and discussing

all the detail needed to understand the process or processes involved.

The lecturer stops the whole class to get feedback from each group regarding

the questions they have formulated. Any irrelevant question or problems are

266

dealt with.

The students then use the information gathered from the questions and

discussions to develop a solution to the problem within a specified time. The

lecturer moves between the groups and assists individuals or groups with

problems.

At the end of the time feedback is given from each group and problems are dealt

with. The process is repeated until the lecture comes to ends.

Students are given homework to do for the next lecture.

267

5.7 Proposed Louw’s General Model for Engineering Courses

Student

group interaction

Introduction to basic


theories in engineering

courses

Student 1

Do an example with class

applying GEBL principles

Student 5 Student 4

Student 3

Student 2

Present groups with

new problems to solve

using GEBL approach

Students listen and

take notes

Students take part

in formulating

questions to

analyse problem

1

1

2

3

2

3

Students work in groups and lecturer acts as facilitator

Lecturer

268

ACKNOWLEDGEMENTS

The opportunity granted by WSU’s Faculty of Education to enroll for this study, the

professional and academic support from WSU’s Directorate of Postgraduate Studies and

the financial support from WSU’s Directorate of Research Development are gratefully

acknowledged.

269

REFERENCES

Adams, J. T., Kaczmarczyk, S., Picton, P. & Demian, P., 2007. Improving problem solving and encouraging creativity in engineering undergraduates. In: International Conference on Engineering Education. 3-7 September 2007. Portugal: Coimbra. Alters, B. J. & Nelson, C. E., 2002. Perspective: Teaching evolution in higher education. International Journal of Organic Evolution, 56(10), pp.1891-1901. Altuger, G., Tumkor, S. & Chassapis, C., 2009. Introduction to the mechanical engineering discipline through hands-on product development case studies, US – Turkey workshop on rapid technologies, 24 September 2009, pp.59-62. Anderson, E. E., Taraban, R. & Sharma, M. P., 2005. Implementing and assessing computer-based active learning materials in introductory thermodynamics. International Journal of Engineering Education, 21(6), pp.1168-1176. Aquirre, E., Jacmot, C., Milgrom, E., Raucent, B., Soucisse, A. & Vander Borght C., 2001. Meeting the needs of our stake holders. In: Engineering a new engineering curriculum at UC Louvain SEFI conference. 12-14 September 2001. Netherlands: Copenhagen. Armarego, J., 2007. Deconstructing students’ attitude to learning: A case study in IT education. In: Proceedings of the 2007 computer science and IT education conference. 16-18 November 2007. The Republic of Mauritius. Ary, D., Jacobs, L. C., Razavieh, A. & Sorensen, C., 2010. Introduction to research in education. 8th ed. Belmount, CA: Wadsworth. Australian Catholic University Learning and Teaching Plan 2009-2011. Avison, D., Lau, F., Myers, M. & Nielsen, P. A., 1999. Action research. Communications of the ACM, 42(1), pp.94-97. Aziz, E. & Chassapis, C., 2008. Introduction to the ME curriculum through product engineering case studies. In: 38th ASEE/IEEE Frontiers in education conference, 22-25 October 2008. USA: Saratoga Springs, NY. Bales, E., 1996. Corporate universities versus traditional universities: friends or foes? Third annual EDINEB (Educational Innovations in Economics and Business)

270

international conference. USA: Orlando, Florida. Bardet, J., & Ragusa, G., 2009. Analysis of body of knowledge in civil engineering. American Society for Engineering Education. Barrows, H. S., 1986. ‘A Taxonomy of Problem Based Learning Methods’, Medical education, 20, pp.481-486. Bless, C., Higson-Smith, C. & Kagee, A., 2006. Fundamental of social research: An african perspective. 4th ed. Cape Town: Juta. Board of European Students of Technology, 2006. “Active Learning in Engineering Education”. Symposium on education. 1-6 May 2006. Portugal: Porto. Boles, W., Beck, H. & Hargreaves, D., 2005. Deploying Bloom’s taxonomy in a work integrated learning environment, ASEE/AAEE 4th global colloquium on engineering education. Borrego, M., Douglas, E. P. & Amelink, C. T., 2009. Quantitative, qualitative, and mixed research methods in engineering education. Journal of Engineering Education, 98(1), pp.53-66. Boud, D. & Felleti, G., 1998. The challenge of problem-based learning. 2nd ed. London: Routledge. Bower, K. C., Mays, T. W. & Miller, C. M., 2004. Small group, self-directed problem based learning development in a traditional engineering program. In: 34th ASEE/IEEE frontiers in education conference. 20-23 October 2004. GA: Savannah. Brannick, T. & Coghlan, D., 2007. In defense of being ‘native’: The case for insider academic research. Organizational Research Methods, 10(1), pp.59-74. Brodie, L. & Gibbings, P., 2007. Developing problem based learning communities in virtual space. In: Connected 2007 international conference on design education. 9-12 July 2007. Australia: Sydney. Bryman, A. ed., 1989. Research methods and organization studies. London: Routledge. Burns, N. & Grove, S. K., 2004. The practice of nursing research: conduct, critique, and utilization. 5th ed. St Louis: Elsevier Saunders. Cano, V., 2000. Reliability & Validity in Qualitative Research. Available at: http://www.qmu.ac.uk/psych/Rtrek/study_notes/web/sn5.htm.

271

Carbone, A. C., Conway, D. & Farr, G., 2004. Techniques for effective tertiary teaching, school of computer science and software engineering, Monash University. Carmine, E. G. & Zeller, R. A., 1979. Reliability and validity assessment. London: Sage. Case, J. M. & Marshall, D., 2009. Approaches to learning. In: Tight, M., Huisman, J., Mok, K. H. & Morpew, C. ed. The Routledge International Handbook of Higher Education. London and New York: Routledge Falmer. Castles, R., Lohani, V. K. & Kachroo, P., 2009. Utilizing hands-on learning to facilitate progression through Bloom’s taxonomy within the first semester. In: 39th ASEE/IEEE frontiers in education conference, 18-21 October 2009. TX: San Antonio. Chang, R. L., Stern, L., Sondergaard, H. & Hadgraft, R., 2009. Places for learning engineering: A preliminary report on informal learning spaces. In: Proceedings of the research in engineering education symposium, 2009. Australia: Palm Cove, QLD. Charlevoix, D., Strey, S. & Mills, C., 2009. Design and implementation of enquiry-based, technology-rich learning activities in a large enrollment blended learning course. Journal of the Research Centre for Educational Technology, 5(3), pp.15-28. Committee of Technikon Principals (CTP), 2001, What is a Technikon? Available at: http://www.technikons.co.za/whatistech/techintro.html. Cope, C., 2003. Educationally critical characteristics of deep approaches to learning about the concept of an information system. Journal of Information Technology Education, 2, pp.415-427. Council on Higher Education, 2007. Higher education monitor, a case for improving teaching and learning in South African higher education, HE Monitor no.6, pp.26- 27. Craig, A., Joines, J., Miller, C., Miller, T., Raubenheimer, D., Rouskas, G., Silverberg, L. & Wiebe, E., 2008. Computing across curricula. In: ASEE Annual conference. June 2008. USA: Pittsburgh, PA. Creswell, J. W., 2003. Research design: qualitative, quantitative, and mixed method approaches. 2nd ed. Thousand Oaks, CA: Sage. Cronbach, L. J., 1951. Coefficient alpha and the internal structure of tests. Psychometrika, 16, pp.297-334.

272

Davis, B. G., 1993. Tools for teaching. San Francisco: Jossey-Bass. Davis, C. & Wilcock, E., 2008. Teaching materials using case studies, UK centre for materials education. De Graaf, E., Saunders-Smits, G. & Nieweg, M., 2005. Research and practice of active learning in engineering education. 1st ed. Netherlands: Amsterdam University Press. Delaney, K. & Kelleher, J., 2008. Real-world process design for mechanical engineering students: A case study of PBL in Dublin Institute of Technology. In: International symposium for engineering education, ISEE-08. Ireland: Dublin. De La Harpe, B. & Radloff, A., 2007. The value of assessing learning strategies for effective learning and teaching: strengthening the partnership between learners and teachers. Curtin business school, Curtin University of Technology. Faculty of Life Sciences, RMIT University. De Weck, O. L., Young, P. W. & Adams, D., 2003. The three principles of powered flight: An active learning approach. In: American society for engineering education annual conference & exposition. 22-25 June 2003. USA: Nashville, Tennessee. Ditcher, A. K., 2001. Effective teaching and learning in higher education, with particular reference to the undergraduate education of professional engineers. International Journal of Engineering Education, 17(1), pp.24-29. Donath, L., Spray, R., Thompson, N. S., Alford, E. M., Craig, N. & Matthews, M. A., 2005. Characterizing discourse among undergraduate researchers in an enquiry-based community of practice. Journal of Engineering Education, 94(3), pp.403-417. Downward, P. & Mearman, A., 2006. Retroduction as mixed-methods triangulation in economic research: reorienting economics into social science. Cambridge Journal of Economics, pp.1-23. Druckman, D., 2005. Doing research: methods of enquiry for conflict analysis. London: Sage. Edwards, R. & Recktenwald, G., 2008. Guided enquiry in an engineering technology classroom. In: American society for engineering education annual conference and exposition. USA: Pittsburgh, PA. Elshorgaby, A. & Schonwetter, D. J., 2002. Engineering morphing: bridging the gap

273

between classroom teaching and the engineering profession. International Journal of Engineering Education, 18(3), pp.295-300. Elston, R. & Johnson, W., 1994. Populations, samples and study design. In: Essentials of biostatistics. 2nd ed. Philadelphia: Davis Company. Engineering Council of South Africa, 2009. Criteria for accreditation of engineering programs meeting stage 1 requirements. Available at: http://www.ecsa.co.za/documents/080207_E-03- P_Criteria_For_Accreditation.pdf Farrell, S. & Hesketh R. P., 2000. An inductive approach to heat and mass transfer. In: American society for engineering education annual conference. USA: Glassboro, New Jersey. Felder, R. M. & Brent, R., 2003. Learning by doing. Chemical Engineering Education, 37(4), pp.282-283. Felder, R. M. & Brent, R., 2010. The national effective teaching institute: assessment of impact and implications for faculty development. Journal of Engineering Education, 99(2), pp.121-134. Felder, R. M. & Silverman, L. K., 1988. Learning and teaching styles in engineering education. Journal of Engineering Education, 78(7), pp.674-681. Felder, R. M., Woods, D. R., Stice, J. E. & Rugarcia, A., 2000. The future of engineering education II: teaching methods that work. Chemical Engineering Education, 34(1), pp.26-39. Ferreira, J. M. & Mueller, D., 2004. The Marvel EU project: a social constructivist approach to remote experimentation. Fink, L. D., 2003. What is “Significant Learning”? Author of creating significant learning experiences: an integrated approach to designing college courses. San Francisco, CA: Jossey-Bass. Flick, U., 2006. An introduction to qualitative research. 3rd ed. London: Sage. Floyd, K. S., Harrington, S. J. & Santiago J., 2009. The effect of engagement and perceived course value on deep and surface learning strategies. Informing Science: The International Journal of an Emerging Transdiscipline, 12, pp.181- 190.

274

Fowler, D. A., 2004. Defining and determining the impact of a freshman engineering student’s approach to learning (surface versus deep). Ph. D. Texas: A & M University. Fraser, B. J. & Tobin, K., 1997. International handbook of science education hardback. Netherlands: Kluwer Academic Publishers Group. Fuehne, J., 2007. Experience with active learning, frequent assessment and student evaluations. In: American society for engineering education Illinois-Indiana section conference. Spring 2007. USA: Indianapolis, Indiana. Gaither, G., Nedwek, B. P. & Neal, J. E., 1994. Measuring up: the promises and pitfalls of performance indicators in higher education. ASHE-ERIC Higher Education Report Series, 94-5, volume 23-5. Available at: http://www.ntlf.com/html/lib/bib/94-5dig.htm Gallow, D., 2000. Problem-Based Learning Faculty Institute, What is Problem-Based Learning? Available at: http://www.pbl.uci.edu/whatispbl.html Geer, U. C. & Rudge, D. W., 2004. A review of research on constructivist-based strategies for large lecture science classes. Available at: http://wolfweb.unr.edu/homepage/crowther/ejse/geer.pdf Gibson, I. S., 2002. Assessment in engineering education, a European perspective. International Journal on Engineering Education, 18(4), pp.465-471. Goldfinch, T., Carew, A. L. & McCarthy, T., 2008. Improving learning in engineering mechanics: the significance of understanding. In: Australasian association for engineering education conference. Australia: Yeppoon, Queensland. Hanrahan, H., 2007. Developing engineering qualifications within the South African NQF: a view from ECSA. In: Proceedings of the 7th Q-Africa conference. Available at: http:// www.saqa.org.za/docs/conference/qafrica/2007/developing.pdf Hanson, D. M., 2006. Instructor’s guide to process-oriented guided-enquiry learning. Lisle, IL: Pacific Crest. Hardjito, D., 2010. The use of scaffolding approach to enhance students’ engagement in learning structural analysis. International Education Studies, 3(1), pp.130-135. Hay, D. B., 2007. Using concept maps to measure deep, surface and non-learning outcomes. Studies in higher education, 32(1), pp.39-57.

275

Hester, E. L., 1995. Successful marketing research: the complete guide to getting and using essential information about your customers and competitors. Canada: Wiley & Sons. Hesketh, R. P., Farrell, S. & Slater C. S., 2002. The role of experiments in inductive learning. In: Proceedings of the American society for engineering education annual conference & exposition. June 2002. Canada: Montreal. Heukelom, F., 2009. Origin and interpretation of internal and external validity in economics. Nijmegen center for economics, working paper 09-111, August 2009. Available at: http://www.ru.nl/nice/workingpapers Higher Education Management Information System, 2009. Hodkinson, P., 2005. ‘Insider Research’ in the study of youth cultures. Journal of Youth Studies, June 2005, 8(2), pp.131-149. Holford, K. M. & Moore, C. J., 1994. Engineers fit for industry. Staff and educational development association, the new academic volume 3(1993/4), Vol. 3.2. Holloway, I., 1997. Basic concepts for qualitative research. New Jersey: Wiley – Blackwell. Hopson, M. H., Simms, R. L. & Knezek, G. A., 2002. Using a technology-enriched environment to improve higher-order thinking skills. Journal of Research on Technology in Education, 34(2), Winter 2001-2002, pp.109-119. Huet, S., Mourtos, N. J., Costa, N., Pacheco, O. & Tavares, J., 2007. Models for research-based teaching in engineering courses: a case study at the University of Aveiro (PT) and San Jose University (USA). In: International conference on engineering education. 3-7 September 2007. Portugal: Coimbra. Huizer, G., 1997. Participatory action research and people's participation: introduction and case studies. Available at: http://www.fao.org/WAICENT/FAOINFO/SUSTANDARDEV/PPdirect/PPre0020.htm

Hyslop-Margison, E. J. & Strobel, J., 2008. Open forum, constructivism and education: misunderstandings and pedagogical implications. The Teacher Educator, 43, pp.72-86. Indian Express.com, 2009. August 10th.

276

Irish, R., 1999. Engineering thinking: using Benjamin Bloom and William Perry to design assignments. Language and Learning Across the Disciplines, 3(2), pp.83-102. Integrated Tertiary Software records, WSU, 2008. Jollands, M., McCallum, N. & Bondy, J., 2009. If students want feedback why don’t they collect their assignments? In: 20th Australasian association for engineering education conference. 6-9 December 2009. Australia: Adelaide. Jones, M. G. & Brader-Araje, L., 2002. The impact of constructivism on education: language, discourse, and meaning, school of education, University of North Carolina, Chapel Hill. American Communication Journal, 5(3). Available at: http://acjournal.org/holdings/vol5/iss3/special/jones.htm Jones, R. C., 1998. World expertise llc, global status of engineering education, outcomes of the global congress on engineering education at Cracow, Poland. Available at: http://www.worldexpertise.com/global_status_of_engineering_edu.htm

Joughin, G., 2003. Oral assessment from the learner’s perspective: the experience of oral assessment in the post-compulsory education. Ph. D. Brisbane: Griffith University. Available at: http://www4.gu.edu.au:8080/adt-root/uploads/approved/adt- QGU20031125.091403/public/02Whole.pdf

Junglas, P., 2006. Simulation programs for teaching thermodynamics. Global Journal of Engineering Education, 10(2), pp.175-180. Kabir, K. B., Khan, M. S. & Mahmud, I., 2008. Novel ideas on engineering education in Bangladesh. Chemical Engineering Research Bulletin, (12), pp.11-19. Kapadia, R. J., 2008. Teaching and Learning Styles in Engineering Education. In: 38th ASEEIEEE frontiers in education conference. 22-25 October 2008. USA: Saratoga Spring, New York. Kapranos, P., 2007. 21st Century teaching & learning: Kolb’s cycle & reflective thinking as part of teaching, creativity, innovation, enterprise and ethics to engineers. In: International symposium for engineering education 2007. Ireland: Dublin. Kaw, A. K., Besterfield, G. H. & Eison, J., 2005. Assessment of a web-enhanced course in numerical methods. International Journal on Engineering Education, 21 July, 21(4), pp.712-722.

277

Kaw, A. & Garapati, S., 2010. Development of digital audiovisual lectures for an engineering course: a you tube experience. In: American society for engineering education southeast section conference. USA: South Florida. Killen, R., 2006. Effective teaching strategies: lessons from research and practice. 4th ed. Spain: Social Science Press. Kirk, J. & Miller, M. L., 1986. Reliability and validity in qualitative research. 8th ed. Beverly Hills, CA: Sage. Kitto, K. L., 2009. Using cooperative writing and oral presentations as peer teaching - evaluating the effectiveness of elements of inductive teaching and social constructivism on student outcomes. In: 39th ASEE/IEEE frontiers in education conference. 18-21 October 2009. Texas: San Antonio. Kitto, K. L., 2010. Understanding the effectiveness of cognitive and social constructivism, elements of inductive practice, and student learning styles on selected learning outcomes in materials engineering. In: 40th ASEE/IEEE frontiers in education conference. 27-30 October 2010. USA: Washington, DC. Klentschy, M., & Thompson, L., 2008. Scaffolding science enquiry through lesson design: using a research-based template to plan classroom instruction. Portsmouth, NH: Heinemann. Kok-Soo, T., 2003. Project-based learning in engineering education: an approach used by Monash University Malaysia. In: International conference on engineering education, 21-25 July 2003, Spain: Valencia. Kuri, N. P., 2000. Kolb’s learning cycle: an alternative strategy for engineering education. Available at: http://www.ineer.org/Events/ICEE1998/ICEE/papers/225.pdf Lamancusa, J. S., Zayas, J. L., Soyster, A. L., Morell, L. & Jorgensen, J., 2008. The learning factory: industry-partnered active learning. Journal of Engineering Education, 15 May, 97(1), pp.1-15. Lattuca, L. R., Terenzini, P. T., Volkwein, J. F. & Peterson, G. D., 2006. The changing face of engineering education. The Bridge, 36(2), pp.5-13. Lee, V. S., 2004. Teaching and learning through enquiry: a guidebook for institutions and instructors. Sterling, VA: Stylus. Lincoln, Y. S. & Guba, E. G., 1985. Naturalistic enquiry. London: Sage.

278

Linsey, J., Talley, A., White, C. & Jensen, D., 2009. From tootsie rolls to broken bones: an innovative approach for active learning in mechanics of materials. In: American Society for Engineering Education - Advances in Engineering Education, 1(3), pp.18-19. Litzinger, T. A., Lattuca, L. R. & Hadgraft, R. G., 2011. Engineering education and the development of expertise. Journal of Engineering Education, 100(1), pp.123-150. Lublin, J., 2003. Deep, surface and strategic approaches to learning. centre for teaching and learning good practice in teaching and learning, University College Dublin, pp.1-11. Ma, A. W. W., 2009. Computer supported collaborative learning and higher order thinking skills: a case study of textile studies. Interdisciplinary Journal of E- Learning and Learning Objects, 5, pp.145-167. Maier, P., Barnett, L., Warren, A. & Brunner, D., 1998. Using technology in teaching and learning. New York: Routledge. Marshall, C. & Rossman, G. B., 2006. Designing qualitative research. 4th ed. Thousand Oaks, CA: Sage. Martin, D. J., 2009. Elementary science methods: a constructivist approach. 5th ed. Belmount, CA: Wadsworth. Martin, R., Maytham, B., Case, J. & Fraser, D., 2005. Engineering graduates’ perceptions of how well they were prepared for work in industry. European Journal of Engineering Education, 30(2), pp.167-180. Materu, P. N., 2007. Higher education quality assurance in Sub Saharan Africa: status, challenges, opportunities, and promising practices. Washington: The World Bank. Mazumder, Q. H., 2010. Metacognition approaches to enhance student learning in mechanical engineering classroom. In: World congress on engineering, 2, June 30-July 2, U.K: London. McKenna, A. F., Yalvac, B. & Light, G. J., 2009. The Role of collaborative reflection on shaping engineering faculty teaching approaches. Journal of Engineering Education, 98, pp.17-26. Merriam, S. B., 1995. What can you tell from an N of 1?: issues of validity and reliability in qualitative research – theory to practice. PAACE Journal of Lifelong Learning, 4, pp.51-60.

279

Michaelides, I., Eleftheriou, P. & Muller, D., 2004. A remotely accesseble solar energy laboratory - a distributed learning experience. In: 1st Remote engineering and virtual instrumentation international symposium (REV'04), 28-29 September 2004. Austria: Villach. Miller-Young, J., 2007. CSI (Crash Scene Investigation): An inquiry-based learning project. American society for engineering education. 2007. USA: Hattiesburg, MS. Mohammadi, I. M., 2008. Department of agricultural extension education, college of agriculture, University of Tehran, Karaj, Iran, variables refinery process to ensure research unbiasedness (validity) and invariance (reliability) in agricultural extension and education. American Journal of Agricultural and Biological Sciences, 3(1), pp.342-347. Naher, S., Brabazon, D. & Looney, L., 2008. Affects of student attendance on performance in undergraduate materials and manufacturing modules. International symposium for engineering education. 8-10 September. Ireland: Dublin. Nicklow, J., Kowalchuk, R., Gupta, L., Tezcan, J. & Mathias, J., 2009. A short-term assessment of a multi-faceted engineering retention program, Southern Illinois University. In: 39th ASEE/IEEE frontiers in education conference. 18-21 October 2009. TX: San Antonio. Nicol, D. J. & Boyle, J. T., 2003. Peer instruction versus class-wide discussion in large classes: a comparison of two interaction methods in the wired classroom. Studies in Higher Education, 28(4), pp.457-473. Nilson, L. B., 2010. Teaching at its best: a research-based resource for college instructors. 3rd ed. San Francisco, CA: Jossey-Bass. O'Dwyer, A., 2008. Learning styles of first year level 7 electrical and mechanical engineering students at DIT. In: Proceedings of the international symposium for engineering education ISEE-08, 1 January, pp.69-74. O’Dwyer, A., 2009. Analysis of learning styles of first year engineering students on two Level 7 programmes. In: All-Ireland society for higher education (AISHE) conference. Ireland: NUI, Maynooth. Ogot, M. & Okudan, G. L. E., 2006. Systematic creativity methods in engineering education: a learning styles perspective. International Journal of Engineering Education, 22(3), pp.566-576.

280

Orlich, D. C., Harder, R. J., Callahan, R. C., Trevisan, M. S. & Brown, A. H., 2007. Teaching strategies: a guide to effective instruction. 9th ed. Boston, MA: Wadsworth. Pendergrass, N. A., Kowalczyk, R. E., Dowd, J. P., Laoulache, R. N., Nelles, W., Golen, J. A. & Fowler, E., 1999. Improving first-year engineering education. In: 29th ASEE/IEEE frontiers in education conference, 10-13 November 1999. USA: San Juan, Puerto Rico. Prince, M., 2004. Does active learning work? Review of research, department of chemical engineering Bucknell University. Journal of Engineering Education 93(3), pp.223-231. Prince, M. J. & Felder, R. J., 2006. Inductive teaching and learning methods: definitions, comparisons and research bases. Journal of Engineering Education, 95(2), pp.123-138. Prince, M. & Hoyt, B., 2002. Helping students make the transition from novice to expert problem-solvers. In: 32nd ASEE/IEEE frontiers in education conference. 6-9 November 2002. USA: Boston, MA. Punch, K., 2005. Introduction to social research: quantitative and qualitative approaches. 2nd ed. London: Sage. Pundak, D., Herscovitz, O., Shacham, M. & Wiser-Biton, R., (2009) Instructors' attitudes toward active learning. Interdisciplinary Journal of E-Learning and Learning Objects, (5), pp.215-226. Purcell, P., 2007. Engineering student attendance at lectures: effect on examination performance, University College Dublin, Ireland. In: International conference on engineering education. 3-7 September 2007. Portugal: Coimbra. Qualters, D. M., Sheahan, T. C. Mason, E. J., Navick, D. S. & Dixon M., 2008. Improving learning in first-year engineering courses through interdisciplinary collaborative assessment. Journal of Engineering Education, 97(1), pp.37-45. Ramsuroop, S., 2011. Developing engineering conceptual competencies in chemical engineering students through socially relevant diy projects. In: Proceedings of the 1st Biennial conference of the South African society for engineering. 10-12 August 2011. SA: Stellenbosch. Reagan, T. G. & Osborn, T. A., 2002. The foreign language educator in society: toward a critical pedagogy. Mahwah, NJ: Lawrence Erlbaum Associates.

281

Reason, P., 1994. Three approaches to participative enquiry. Research and action enquiry: three approaches to participative enquiry. Prepared for the handbook of qualitative research, edited by Denzin, N. K. & Lincoln, Y. S. Thousand Oaks: Sage. Reason, P. & Bradbury, H., 2008. The Sage handbook of action research: participative enquiry and practice. 2nd ed. London: Sage. Reid, G., 2005. Learning styles and inclusion. London: Sage. Reeves, J., Courter, S., Nickels, K., Noyce, D., Pearce, A., Schaefer, L., Wickramasinghe, R. & Lyle, R., 1999. Change agents: immediately implementable teaching and educational hints from the engineering education scholars program. In: American society for engineering education annual conference. 20-23 June 1999. USA: Charlotte, North Carolina. Richards, L. G. & Schnittka, C. G., 2007. Workshop - bringing engineering into middle schools: learning science and math through guided enquiry and engineering design. In: 37th ASEE/IEEE frontiers in education conference. 10-13 October 2007. USA: Milwaukee, WI. Ritchie, J., Zwi, A. B., Blignault, I., Bunde-Birouste, A. & Silove, D., 2009. Insider- outsider positions in health-development research: reflections for practice. Development in Practice, 19(1), pp.106-112. Robbins, D. & Ardebili, M., 2006. Engineering students’ conceptions of heat and temperature pre and post thermodynamics course. American Society of Engineering Education, pp.1-9. Roe, B. E. & Just, D. R., 2009. Internal and external validity in economics research: tradeoffs between experiments, field experiments, natural experiments and field data. In: 2009 ASSA annual meeting. USA: San Francisco, CA. Rose, C. P., Kumar, R., Aleven, V., Robinson, A. & Wu, C., 2006. Cycle talk: data driven design of support for simulation based learning. International Journal of Artificial Intelligence in Education Special Issue of the Best of ITS ’04, 16, pp.195-223. Rugarcia, A., Felder R. M., Woods D. R. & Stice J. E., 2000. The future of engineering education. 1. A vision for a new century. Chemical Engineering Education, 34(1), pp.16-25.

282

Rutkowski, J., Moscinska, K. & Jantos, P., 2010. Application of Bloom’s taxonomy for increasing teaching efficiency – case study. In: International conference on engineering education. 18-22 July 2010. Poland: Gliwice. Salmi, J., 2001. Tertiary education in the 21st century: challenges and opportunities. Journal of the Programme on Institutional Management in Higher Education, 13(2), pp.105-131. Sandoval, W. A., 2005. Understanding students’ practical epistemologies and their influence on learning through enquiry. 27 May, pp.634-656. Available at: http://www.interscience.wiley.com Savage, R. N., Chen, K. C. & Vanasupa, L., 2007. Integrating project-based learning through-out the undergraduate engineering curriculum, submitted to the J. STEM education, October 2006. Schofield, A., 2007. The Higher education academy - embedding strategies to enhance learning and teaching in Scottish HEIs: an approach to self-assessment. Serfontein, D. E. & Fick, J. I. J., 2011. Implementation experience with project-based inductive learning in an introductory undergraduate module in nuclear engineering. In: Proceedings of the 1st Biennial conference of the South African society for engineering. 10-12 August 2011. SA: Stellenbosch. Shenton, A. K., 2004. Strategies for ensuring trustworthiness in qualitative research projects. Education for Information, 22(2), pp.63-75. Smith, B. L. & MacGregor, J. T., 1992. What is collaborative learning?: A sourcebook for higher education, University Park, national center on postsecondary teaching, learning, and assessment, Pennsylvania State University. South African Qualifications Authority document on the registered National Diploma Mechanical Engineering, 2009. Spronken-Smith, R., Angelo, T., Matthews, H., O’Steen, B. & Robertson, J., 2007. How Effective is enquiry-based learning in linking teaching and research? Available at: http://portal-live.solent.ac.uk/university/rtconference/colloquium_papers.aspx

Stappenbelt, B., 2010. The influence of action learning on student perception and performance. Australasian Journal of Engineering Education, 16(1), pp.1-12. Strangman, N. & Hall, T. E., 2004. Background knowledge, MA: national center on accessing the general curriculum. Available at: http://www.cast.org/publications/ncac/ncac_backknowledge.html

http://www.cast.org/publications/ncac/ncac_backknowledge.html

283

Su, K. D., 2008. An integrated science course designed with information communication technologies to enhance university students’ learning performance. Computers & Education, 51(2008), pp.1365-1374. Available at: http://www.sciencedirect.com Taraban, R., Anderson, E. E., De Finis, A., Brown, A. G., Weigold, A. & Sharma, M. P., 2007. First steps in understanding engineering students’ growth of conceptual and procedural knowledge in an interactive learning context. Journal of Engineering Education, 96(1), pp.57-68. Terry, R. E. & Harb, J. N., 1993. Kolb, Bloom, creativity, and engineering design. In: ASEE Annual Conference Proceedings. 20-24 June 1993. USA: Illinois-Urbana. Tesch, R., 1990. Qualitative research: analysis types and software tools. London: Routledge. Thiétart, R. A., 2001. Doing management research: a comprehensive guide. Thousand Oaks, CA: Sage. Thompson, N. S., Alford, E. M., Liao, C., Johnson, R. & Matthews, M. A., 2005. Integrating undergraduate research into engineering: a communications approach to holistic education. Journal of Engineering Education, 94(3), pp.297- 307. Tinker, C. & Armstrong, N., 2008. From the outside looking in: how an awareness of difference can benefit the qualitative research process. The Qualitative Report, (13)1, pp.53-60. Tharp, R. & Gallimore, R., 1988. Rousing minds to life. New York: Cambridge University Press. Tully, M. F. & Clarke, D. P., 2008. Use of the infinity project to improve student recruitment and retention on university engineering programmes and apprenticeship training in Ireland. In: International conference on engineering education, 2008. Hungary: Budapest. University of Johannesburg, strategic planning and resourcing, 2007. Uziak, J., Oladiran, M. T. & Moalosi, R., 2010. Reviewing and developing course descriptions to comply with accreditation requirements. Global Journal of Engineering Education, 12(1), pp.30-37. van Niekerk, W., Mentz, E. & Smit, W., 2011. Co-operative learning in thermodynamics: solving problems in pairs. In: Proceedings of the 1st Biennial

http://www.sciencedirect.com/

284

conference of the South African society for engineering. 10-12 August 2011. SA: Stellenbosch. Vlasceanu, L., Grunberg, L. & Parlea, D., 2007. Quality assurance and accreditation: a glossary of basic terms and definitions. UNESCO-CEPES 2007. Romania: Bucharest. Walter Sisulu University faculty prospectus, 2010. Weir, J. A., 2004. Active learning in transportation engineering. Ph. D. Massachusetts: Worcester Polytechnic Institute. Woollacott, L., 2011. MIGs: Mediated interaction groups for enhancing learning among engineering students. In: Proceedings of the 1st Biennial conference of the South African society for engineering. 10-12 August 2011. SA: Stellenbosch. Yaman, S., 2005. Teacher learning and change: consistency between personal theories and behaviours. Mersin University Journal of the Faculty of Education, 1(1), pp.24-47. Ying, Y., 2003. Using problem-based teaching and problem-based learning to improve the teaching of electrochemistry. The China Papers, pp.42-47. Zubair, S. M. & Antar, M. A., 2004. Project-based teaching and learning in thermo- fluid courses. Available at: http://www.engconfintl.org/8axabstracts/Session%205A/rees08_submission_84.doc

Żywno, M. S., 2003. Hypermedia instruction and learning outcomes at different levels of Bloom’s taxonomy of cognitive domain. Global Journal of Engineering Education, 7(1), pp.59-70.

285

APPENDICES

Appendix 1 – Structured Questionnaire testing students experience with

GEBL

Items Strongly

agree

Agree Neutral Disagree Strongly

disagree

1. I enjoyed the group sessions. 10 4 0 1 0

2. The enquiry based sessions helped me to analyse problems effectively.

11

4

0

0

0

3. When working alone the enquiry- based approach helped me to analyse problems effectively.

5 4 6 0

0

4. This method helped me to understand the work and not to just memorise it.

10

4

1

0

0


4

10

1

0

0

6. The Thermodynamics booklet with questions and answer discussions helped me to understand the work better.

9

5

0

1

0

2. 7. The Thermodynamics booklets’ additional questions and answers helped me to understand and analyse new problems better.

4

9

2

0

0

3. 8. This method can help me to understand other courses better.

6 7 1 1 0

9. This method should also be introduced in other courses.

9

5

0

0

1

286

Appendix 2 – Qualitative interviews with students participating in GEBL

Interview schedule

The interview will be based on the students involved with GEBL group sessions and who

made use of the MTHE2 booklet on enquiry learning. The purpose of the interview will

be to determine the students experience and opinions with regard to this method of

teaching. The interviews will be approximately twenty minutes.

Please state for the record your Name, Surname, Age, Race, Gender, Student number

and whether you were enrolled for MTHE2 with Mr Louw.

Could you kindly confirm that you were thoroughly briefed about the purpose of this

interview, that you received a letter explaining its purpose and that you signed an

informed consent form. You also realise that your participation is voluntary and that you

are under no obligation to answer all the questions and that you may withdraw at any

time during the interview.

Items Follow-up

Item 1

The group sessions were very

enjoyable.

If yes, explain what

exactly you enjoyed.

In terms of interaction

with peers did the

sessions made the

course more enjoyable?

If no, explain why not.

287

Item 1a

The group sessions motivated you

to come prepared to class.

If yes, explain why the

group sessions made

you feel responsible to

come prepared to the

next class?

If no, explain why not.

Item 1b

The group sessions helped

developing your communication

skills.

If yes, explain how did

the group sessions

develop your

communication skills?

If not, explain why not.

Did you not take part in

group discussions?

Item 2

The enquiry based sessions helped

me to analyse problems

effectively.

If yes, explain how the

group sessions helped

you in analysing

problems.

Are you not relying too

much on group member

support?

What exactly about this

method helped you to

analyse problems more

effectively?

If not, explain why it

did not help.

What could have been

done to change this?

Item 3

If yes, explain how the

If not, explain why it

288

When working alone the enquiry

based approach helped me to

analyse problems effectively.

enquiry based approach

helped you in analysing

problems when working

on your own.

Explain briefly how you

applied the IB method

when working on your

own.

did not help.



Item 4

This method helped me to

understand the work and not to

just memorise it.

If yes, explain how this

approach helped you to

understand the subject

content better.

Was this better

understanding because

of the different approach

you use in studying the

work?

If no, explain why you

think it did not help.



Item 5

This method helped me develop

the ability to solve problems on

my own.

If yes, explain this ability

that you have developed

to solve problems on

your own – how are you

now more able?

If no, explain why it did

not help.



289

Did the systematic

approach in analysing a

problem together with

your better

understanding of the

course content made

you feel confident that

you are on the correct

track?

Item 6

The Thermodynamics booklet with

questions and answer helped me

to understand the work better.

If yes, explain what in

the booklet helped you

to understand the work

better.

Are you saying you were

manipulating your

approach to get to the

answer?

Did you not find the way

of explaining the work

easier to follow,

understand and to

apply?


not help.

What can be done to

make the booklet more

helpful?

290

Item 7

The Thermodynamics booklet’s

additional questions and answers

helped me to understand and

analyse new problems better.

If yes, explain how

these additional

questions with answers

helped you understand

and analyse problems

better.

Did the additional

questions with answers

helped you to develop

the skill to interpret and

analyse new more

complex problems

easier?

Have you developed the

skill to deal with

problems that you have

never seen before or

that are not similar to

those that you have

done?


not help.

What can be done to

make the booklet more

helpful in understanding

and analysing

problems?

Item 8

This method can help me to

If yes, explain why you

think it will help you

understand other

If no, explain why it will

not help you.

291

understand other courses better.

courses better.

How will you use this

approach to make other

courses easier to

understand?

What intervention can

help you understand

the other courses

better?

Item 9

Any positive or negative

comments on your overall

experience compared to the

traditional teaching method.

Any positive comments

on your overall

experience.

Any negative comments

on your overall

experience.

Item 10

Did this method give you positive

attitude towards the course?

If yes, explain why this

method gave you a

positive attitude towards

the course.

If not, explain why not.

292

Appendix 3 – Formative assessment 1 (semester test 1)

NATIONAL DIPLOMA ENGINEERING: MECHANICAL

DIPLOMA CODE: 3208110

THERMODYNAMICS 2

SUBJECT CODE: 81908922

Student No:__________________

EXAMINER: C LOUW

Surname:____________________

MARKS: 46

Group:______________________

TIME: 90 min

TEST 1

FEBRUARY 2010

Read the problems carefully and answer the questions in the respective spaces

on the answer sheet:

QUESTION 1

An experiment was conducted with a certain gas. It was found that when the

gas is maintained in a constant volume container, 70 kJ/kg of energy are

required to raise the temperature 830C. It is known that = 1,5 for the gas.

1.1 Analyse this question and make a neat drawing of the process before

293

and after the energy was supplied. Indicate all relevant detail

clearly. Explain which variables changed and which ones

remained unchanged during this process;_____________________

______________________________________________________

______________________________________________________

(7)

Explain and calculate:

1.2 the specific heat capacity at constant pressure for the gas;_______

_____________________________________________________

_____________________________________________________

(8)


1.3 the gas constant for this gas.______________________________

____________________________________________________

____________________________________________________

(6)

1.4 During the operation of this device, which readings/factors will

have to be monitored to ensure the safety of the equipment and

people. Explain why these reading/factors can pose a danger to the

equipment and people:___________________________________

_____________________________________________________

_____________________________________________________

294

_____________________________________________________

_____________________________________________________

_____________________________________________________

_____________________________________________________

_____________________________________________________

_____________________________________________________

_____________________________________________________

_____________________________________________________

_____________________________________________________(4)

[25]

QUESTION 2

A closed system undergoes a polytropic process in which the heat added is

17kJ and the internal energy increases by 48kJ. The initial state is 130kPa and

0,15m3 and the final pressure is 800kPa. The gas used in the process was air

and the initial temperature was 300K.

2.1 Analyse this question and make a neat pressure-volume diagram of

the process with all relevant detail indicated clearly. Explain why

the values changed the way they did (e.g. if volume decreased

explain why);___________________________________________

______________________________________________________

______________________________________________________

295

P

V

(11)


2.2 the final volume in the process;_____________________________

______________________________________________________

______________________________________________________

(10)

[21]

296

Appendix 4 – Formative assessment 1b (semester test 1b)



THERMODYNAMICS 2


Student No:__________________

Examiner: C Louw

Surname:____________________

MARKS: 85

Group:______________________

TIME: 2 Hrs

TEST 1b

February 2010



QUESTION 1

A piston-cylinder device with stops is used during an experiment. The

following data was recorded during:

Heat supplied:

mass of air = 0.465kg

297

initial temperature = 270C

initial pressure 200kPa

V1 = 0.2m3

V2 = 0.5m3

P1 = P2

Compression:

T3 = 6000C

V3 = V1

Solution:

1.1 Explain the type of process or processes involved in the question;_______________________________________________

______________________________________________________

______________________________________________________

_____________________________________________________

_____________________________________________________

_____________________________________________________

_____________________________________________________

_____________________________________________________(8)

298

1.2 Reflect the process or processes on the pressure-volume diagram,

with all given information clearly indicated;

P

V

(7)

Explain and determine:

1.3 the total heat flow;

_______________________________________________________

_______________________________________________________

_______________________________________________________

(17)

Explain and determine:

1.4 the amount of heat removed from the air to return it to the initial condition;_____________________________________________

_____________________________________________________

_____________________________________________________

_____________________________________________________

299

_____________________________________________________

_____________________________________________________

_____________________________________________________

_____________________________________________________

_____________________________________________________

(9)

[41]

QUESTION 2

A piston-cylinder device, with a set of stops on the top, initially contains

3kg of air at 200kPa and 270C. Heat is now transferred to the air, and the

frictionless piston rises, keeping the pressure constant, until it hits the stops,

at which point the volume is twice the initial volume. More heat is transferred

until the pressure inside the cylinder also doubles.

Solution:

2.1 Analyse this question and make a neat pressure-volume diagram of the

process with all relevant detail indicated clearly. Explain why the values

changed the way they did (e.g. if volume decreased explain why). Explain

also the type of process or processes involved in the question;

___________________________________________________________

___________________________________________________________

___________________________________________________________

___________________________________________________________

___________________________________________________________

300

P

V

(15)


2.2 the work done;

_____________________________________________________________

_____________________________________________________________

_____________________________________________________________

_____________________________________________________________

_____________________________________________________________

_____________________________________________________________

(10)


2.3 the amount of heat transfer during the complete process.

___________________________________________________________

___________________________________________________________

___________________________________________________________

(19)

[44]

301




THERMODYNAMICS 2


Student No:__________________

Examiner: C Louw

Surname:____________________

MARKS: 55

TIME: 1hr

SEMESTER TEST 2

19 MARCH 2010



QUESTION 1

Air is compressed from 100kPa and 220C to a pressure of 1MPa while being

cooled at a rate of 16kJ/kg by circulating water through the compressor

casing. The volume flow rate of the air at inlet conditions is 150m3/min and

the power input to the compressor is 500kW. Determine:

1.1 Explain the type of process or processes involved in this question;_______

____________________________________________________________

302

____________________________________________________________

____________________________________________________________

____________________________________________________________(4)

1.2 Draw a sketch of the device used in the question with all given information reflected as well as directions of flow;

(3)

Explain and determine the following:

1.3 the mass flow rate of the air; ___________________________________________________________

___________________________________________________________

___________________________________________________________

(4)


1.4 the temperature at the compressor exit:

____________________________________________________________

____________________________________________________________

____________________________________________________________

(4)

1.5 How does the outlet temperature compare to the inlet temperature and what

causes this difference?

_____________________________________________________________

_____________________________________________________________

_____________________________________________________________

303

_____________________________________________________________

_____________________________________________________________

_____________________________________________________________

_____________________________________________________________(5)

1.6 Explain the importance of cooling the compressor during operation and also explain what will be the effect if cooling is not done effectively:

_____________________________________________________________

_____________________________________________________________

_____________________________________________________________

_____________________________________________________________

_____________________________________________________________

_____________________________________________________________

_____________________________________________________________

_____________________________________________________________

_____________________________________________________________(3)

[23]

QUESTION 2

A furnace gas has the following volumetric analysis: H2 15%, CO 24%, CO2 6%,

CH4 12%, O2 3% and N2 40%. Calculate the volumetric analysis of the dry

products of combustion with 30% excess air.

2.1 Explain the type of process or processes involved in the

question;____________________________________________________

___________________________________________________________(1)

2.2 Explain what is required in order for one to be able to do an analysis of

304

products of combustion;________________________________________

___________________________________________________________(3)

2.3 Explain the steps to be followed to calculate all that is required to

do an analysis;_______________________________________________

___________________________________________________________

_____________________________________________________

_____________________________________________________

___________________________________________________________(5)

2.4 Perform the calculations as explained in 2.3:

(11)

2.5 Tabulate your results and explain what these values mean:

(12)

[32]

305




Group: ______________

THERMODYNAMICS 2


Student No:__________________

EXAMINER: C LOUW

Surname:____________________

MARKS: 113 [110 = 100%]

TIME: 3 HRS

SEMESTER – TEST 3

April 2010



QUESTION 1

A quantity of steam at a pressure of 3MPa has a dryness fraction of 0.72.

The steam occupies a volume of 0.4m3. Heat is transferred into the steam

while the pressure remains constant until the steam is dry saturated. The steam

is then cooled at constant volume until the pressure becomes 1.8MPa.

1.1 Explain the type of process or processes involved in the question;________

306

________________________________________________________________

________________________________________________________________(4)

1.2 Reflect the process or processes on the pressure-volume diagram and a

temperature-entropy diagram, with all given information clearly indicated;

P T

V S

(5)


1.3 the heat transfer during the constant pressure process;

____________________________________________________________

____________________________________________________________

____________________________________________________________

(9)


1.4 the percentage of heat flow which is converted into work done; ____________________________________________________________

____________________________________________________________

____________________________________________________________

(7)

307


1.5 the heat transferred during the constant volume process.

____________________________________________________________

____________________________________________________________

____________________________________________________________

(10)

[35]

QUESTION 2

Feed water at 290C is fed to a boiler at a rate of 500 l/h. The isobaric boiler

pressure is 700kPa. The super-heater receives the steam which is 90% dry

and superheats the steam to 4000C.

2.1 Draw a fully detailed pressure-volume and temperature-entropy

diagram of this process.

P T

V S

(5)

308


2.2 energy absorbed by the steam per minute in the:

2.2.1 evaporator;

________________________________________________________

________________________________________________________

________________________________________________________

(8)

2.2.2 super-heater.

_____________________________________________________

______________________________________________________

______________________________________________________

______________________________________________________

(7)


2.3 Calculate the overall efficiency of the plant for a fuel consumption of

70kg/hr. The calorific value of the fuel is 38MJ/kg.

___________________________________________________________

___________________________________________________________

___________________________________________________________

___________________________________________________________

(6)

[26]

309

QUESTION 3

The mass of water accumulated in the separator of a combined separating and

throttling calorimeter during a dryness test is 2.24kg and the mass of the

condensate 24kg. The pressure in the main supply line is 1300kPa and after

throttling the pressure and temperature are 100kPa and 1050C.

3.1 Explain the process or processes involved in the problem;______________

_______________________________________________________________

_______________________________________________________________

_______________________________________________________________(6)

3.2 Make a neat diagram of the unit and indicate the given information clearly;

(4)


3.3 the degree of dryness in the main supply line.

____________________________________________________________

____________________________________________________________

____________________________________________________________

(10)

[20]

310

QUESTION 4

A Rankine cycle power plant has a feed pump, economiser, steam generator,

super-heater, turbine and condenser. Steam enters the turbine at 800kPa and

4000C. Steam leaves the turbine at 40kPa after undergoing reverseble

adiabatic expansion through the turbine. The steam is condensed to saturated

liquid and is pumped back through the system.

4.1 Draw a detailed flow diagram of this plant fully labelled; (4)

4.2 Draw a detailed T-S diagram of the plant. (6)

T

S

311


4.3 the work done by the turbine; _______________________________________________________________

_______________________________________________________________

______________________________________________________________

______________________________________________________________

(7)


4.4 the heat supplied per kg of steam;

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

(8)


4.5 the brake thermal efficiency for a steam consumption of 7.2kg/h

and with a condensate temperature of 340C.

_____________________________________________________________

_____________________________________________________________

_____________________________________________________________

_____________________________________________________________

_____________________________________________________________

(7)

[32]

312

Appendix 7 – Formative assessment (oral test)



THERMODYNAMICS 2


Student No:__________________

EXAMINER: C LOUW

Surname:____________________

TIME: 15 MIN.

SCHEDULED ORAL TEST QUESTIONNAIRE

MAY 2010

Non-flow processes

1. Explain what a non-flow process is. 2 –

2. Define the term ‘reverseble process.’ 2 –

3. What are the differences between the following process: adiabatic,

polytropic and isothermal? 3 –

4. What does the adiabatic index of compression or expansion

mean and how can this value be determined? 3 –

Marks

______

5

313

Flow processes

5. Explain what a flow process is. 2 –

6. List five devices through which flow processes takes place. 5 –

7. Explain the components which constitutes the steady flow

energy equation. 5 –

8. Under which conditions are the kinetic energy, heat flow and

work done neglected when applying this equation? 3 –

Combustion

9. What is meant by ‘the minimum amount of oxygen’? 1 –

10. What is the difference between mass analysis and

volumetric analysis? 2 –

11. Which products of combustion appear in the table for a mass

analysis? 5 –

12. Explain the difference between the HCV and LCV of active

elements. 2 –

13. How is this amount of vapour determined in the case of liquid

and gaseous fuels? 2 –

______

5

314

14. What is the difference in terms of POC when ma and when mT

is supplied? 4 -

15. What is meant by ‘the minimum amount of oxygen’? 1 –

16. What is the difference between mass analysis and

volumetric analysis? 1 –

17. Which products of combustion appear in the table for

a mass analysis? 5 –

18. Explain the difference between the HCV and LCV of active

elements. 2 –

19. How is this amount of vapour determined in the case of liquid

and gaseous fuels? 2 –

20. What is the difference in terms of POC when ma and when mT

is supplied? 4 –

Steam and throttling

21. Explain the different phases of steam and when these

conditions are reached. 2 –

22. What is the meaning of the following terms: saturation

temperature, degree of superheat? 2 -

______

5

315

23. Explain why calorimeters are used. Why is this measurement

important? 3 –

24. Explain when a throttling calorimeter is used and the process

followed to determine the condition of the steam. 2 –

25. Illustrate and explain an adiabatic compression of dry

saturated steam on a T-s diagram. 3 –

26. Illustrate and explain an isothermal expansion process of dry

saturated steam on a T-s diagram. 3 -

27. Explain why it is important to measure the quality of steam

produced by a boiler plant and what instrument is used for

this purpose. 2 –

28. Explain when a separating calorimeter is used and the process

followed to determine the condition of the steam. 2 –

Boiler plant

29. Explain the operation of a boiler plant. Support your answer

with a line diagram 5 –

30. Why is the treatment of feed water important? 4 –

31. What does the boiler efficiency measure? 1 –

32. What does the efficiency of a component e.g. evaporator

______

5

316

mean? 1 –

33. Explain how water is heated in an electrode boiler. 2 –

34. How does the water treatment of an electrode differ from a

fuel boiler? 2 –

35.How does the wrong calorific value of the fuel affect the

performance of the boiler plant? 4 –

36. List important safety devices on a boiler and explain their

function. 3 –

37. Explain the reason for blow-down. 1 –

Rankine cycle

38. Explain the operation of a Rankine cycle. Support you answer

with a diagram. 3 –

39. What is the difference between isentropic and actual

expansion through the turbine? Support your answer

with a sketch. 3 –

40. Explain what is the difference between the Rankine efficiency

and the Brake-thermal efficiency? 2 –

41. What do you understand under the term ‘specific

steam consumption’? 2 –

_____

5

317

Condensers

42. Explain the difference between a surface condenser

and a jet condenser. 1 –

43. What is the advantage in using a surface condenser in terms

of water treatment and turbine work done? 4 –

44. How does the air get into the system? 1 –

45. Why is it important to get rid of the air? 1 –

46. Explain the difference between a dry and a wet air pump. 4 –

PERCENTAGE: __

SIGN:___________

______

5

______

5

______

35

318

Appendix 8 – Summative assessment (final examination)


FACULTY OF SCIENCE, ENGINEERING AND TECHNOLOGY

JUNE 2010

SUBJECT : THERMODYNAMICS II

MAIN EXAMINATION

SUBJECT CODE : MTHE 2/0

SAPSE CODE : 81908922

QUALIFICATION : NATIONAL DIPLOMA: MECHANICAL

ENGINEERING

DIPLOMA CODE : 3208110

EXAMINER : C. LOUW

MODERATOR : I. SUNJKA

INSTRUCTIONS : 1. ANSWER ALL QUESTIONS.

319

2. START EACH QUESTION ON A NEW

PAGE.

3. MARK QUESTIONS CLEARLY.

ANNEXTURES : 1. STEAM TABLES

2. ENTHALPY/ENTROPY CHART.

DURATION : 3 HOURS

MARKS : 117 [110 = 100%]

NUMBER OF PAGES : 3 (INCLUDING COVERPAGE BUT EXCLUDING

ANNEXTURE)

EXAMINATION RULES ARE NOW IN EFFECT.

DO NOT TURN THE PAGE BEFORE TOLD TO DO SO.

320

PAGE 1 OF 3 PAGES SUBJECT: THERMODYNAMICS II

QUESTION 1

A 0.3m3 pressure vessel is used to perform a test on a certain

gas. During the test the gas was first heated and then cooled

to a temperature lower than the initial temperature. The

pressure and temperature at the start of the test was 100kPa

and 400K. At the end of the heating process the temperature

was 700K. The gas was then cooled until the pressure inside the

vessel has dropped to 75kPa. The gas constant of this gas is

0.27kJ/kgK and the adiabatic index of compression and

expansion for this gas is 1.35.

1.1 Analyse this question and make a neat drawing of the complete process. Indicate all relevant symbols and

values supplied; (5)

1.2 Explain which variables changed and which ones

remained unchanged during the processes with reasons; (3)

Calculate:

1.3 the pressure at the end of the heating process; (2)

1.4 the amount of heat supplied to the vessel; (5)

1.5 the amount of heat removed from the vessel; (5)

321

1.6 the overall change in enthalpy of the gas. (2)

1.7 Which reading/s must be closely monitored during the

operation of a pressure vessel to ensure the safety of

equipment and people? Explain why? (2)

[24]

QUESTION 2

Steam at 3000kPa and with a dryness fraction of 0.7 is heated

at constant pressure until the temperature was 4000C. The

steam is now cooled down at constant volume until it is just dry.

2.1 Explain the process or processes involved, which variable/s

stays constant, which ones changes and how does the

condition of the steam changed during each process; (3)


QUESTION 2

Determine:

2.2 the work done by the steam during the heating process; (8)

2.3 the heat supplied to the steam; (6)

2.4 the pressure at which the steam becomes just dry. (2)

322

2.5 Draw a detailed pressure-volume and temperature-entropy

diagram of the complete process reflecting all symbols.

Indicate the area which represents the work done during

the heating process as well as the area which represents

the heat flow during the cooling process. (5)

[24]

QUESTION 3

Water is converted into steam by a boiler plant for the purpose

of melting re-cycled plastic items. The plant consist of an

evaporator, super-heater and air pre-heater. The air pre-heater

increases the incoming air temperature from 250C to 1500C.

Water enters the plant at 140C and leaves the super-heater at 3000C.

The plant operating pressure is 3000kPa and the steam leaving

the evaporator has a dryness fraction of 0.85. The melting process

requires 2000kg/hr of steam and the plant is driven be crude oil at

a rate of 420kg/hr and with a calorific value of 30MJ/kg. The air/fuel

ratio can be taken as 12/1.

Calculate:

3.1 the thermal efficiency of the plant; (4)

3.2 the heat absorbed by the steam in the evaporator in kW; (4)

3.3 the heat absorbed by the steam in the super-heater

expressed per kilogram fuel; (2)

323

3.4 the heat absorbed by the air in the air pre-heater in kJ/hr; (3)

3.5 the percentage of total heat absorption which takes place in the super-heater. (4)


QUESTION 3

3.6 Study the attached flow diagram, and fill in the relevant information (symbols and values) on the diagram. Indicate on the diagram corrections which need to be made to reflect the plant described in the question. (6)

[23]

QUESTION 4

A surface condenser is used to condense process steam for

re-circulation. Air was removed from the system by means of a

wet air pump. This system was then replaced by a dry air pump.

Steam enters the unit at 10kPa and with a dryness fraction of

0.9. Condensate leaves at 290C and the air suction spout

temperature is 24.10C. Cooling water temperature increases from

140C to 250C across the unit. Air leakage into the unit at a rate of

20kg/hr.

4.1 Complete the attached diagram/s, indicate clearly the wet

and dry air pump units and fill in all relevant detail as well

as the directions of flow for air, water and steam; (9)

324

4.2 Explain in terms running cost why it was an improvement

to install a dry air pump. (5)

Calculate:

4.3 the extra amount of condensate lost when using a wet air

pump in kg/hr; (10)

4.4 the condenser efficiency. (2)

[26]

QUESTION 5

A fuel sample consist of the following:

45% H2, 50% C, 1% S, 2% O2 and 2% N.

Calculate:

5.1 the amount of oxygen required for complete combustion

of 1kg of this fuel (show balanced reaction equations); (6)

5.2 the mass analysis of the products of combustion. (10)

5.3 What will be the effect in terms of available heat and the

type of combustion products, if insufficient air was

supplied to the combustion chamber? (4)

[20]

325

Appendix 9 – KPIs for measuring achievement in outcomes with formative

assessments 1, 2 and 3



THERMODYNAMICS 2


EXAMINER: C LOUW

Student No:__________________

Surname:____________________

KPI MEASUREMENT RESEARCH GROUP 2010

TEST NO.: _ QUESTION No.:__

KPIs PERFORMANCE RATING

Students

’ ability

to apply

MTHE 2

principle

s to

analyse

and

solve the

problem

accuratel

y.

Analysis

completely

correct

Minor

misinterpretations

(explanation,

discussion,

definition)

Student made a

single error

Some

misinterpretations

(explanation,

discussion,

definition)

Student made more

than one error

Point values are

indicated correctly

on graph but graph

is incorrect or

partially correct

Major

misinterpretations

(explanation,

discussion,

definition)

Student have one

correct statement

Graph/sketch does

not correspond with

interpretation

Analysis completely

incorrect

5 4 3 2 1

Full mark Full mark allocation Full mark allocation Full mark allocation Full mark allocation

326

allocation

Point

s

1

2

3

4

5

6

7

8

9

10

11

etc

Ou

t

of

1

2

3

4

5

6

7

8

9

10

11

etc

Points

2

3

4

5

6

7

8

9

10

Etc

Out of

3

4

5

6

7

8

9

10

11

etc

Points

1

2

3

4

5

6

Out of

2

4, 5, 6

etc

5, 6, 7

etc

6, 7, 8

etc

7, 8, 9

etc

8, 9, 10

etc

Points

1

Out of

3, 4, 5

etc

Points

0

Out of

1, 2, 3

etc

Halve

mark

allocation

Halve mark

allocation

Halve mark

allocation

Halve mark

allocation

Halve mark

allocation

Point

s

1

2

3

4

5

6

7

8

9

10

11

etc

Ou

t

of

1

2

3

4

5

6

7

8

9

10

11

etc

Points

1.5

2.5

3.5

4.5

5.5

6.5

7.5

8.5

9.5

10.5

etc

Out of

2

3

4

5

6

7

8

9

10

11

etc

Points

1

1.5

2

2.5

3

3.5

4

4.5

5

5.5

6

6.5

etc

Out of

2

3, 4, 5

etc

4, 5, 6

etc

4, 5, 6

etc

5, 6, 7

etc

5, 6, 7

etc

6, 7, 8

etc

6, 7, 8

etc

7, 8, 9

etc

7, 8, 9

etc

8, 9, 10

etc

8, 9 10

etc

Points

0.5

Out of

1, 2, 3

etc

Points

0

Out of

1, 2, 3

etc

327

Analytical

solution

completely

correct

Minor

calculation/substitu

tion errors

Student made one

error

Some


tion errors

Student made more

than one error

Major


tion errors

Student have one

correct


tion

Completely

incorrect


tion

5 4 3 2 1

Full mark

allocation

Full mark allocation Full mark allocation Full mark allocation Full mark allocation

Point

s

1

2

3

4

5

6

7

8

9

10

11

etc

Ou

t

of

1

2

3

4

5

6

7

8

9

10

11

etc

Points

2

3

4

5

6

7

8

9

10

etc

Out of

3

4

5

6

7

8

9

10

11

etc

Points

1

2

3

4

5

6

etc

Out of

2

4, 5, 6

etc

5, 6, 7

etc

6, 7, 8

etc

7, 8, 9

etc

8, 9, 10

etc

Points

1

Out of

3, 4, 5

etc

Points

0

Out of

1, 2, 3

etc

Halve

mark

allocation

Halve mark

allocation

Halve mark

allocation

Halve mark

allocation

Halve mark

allocation

Point

s

1

2

3

4

5

6

7

8

9

Ou

t

of

1

2

3

4

5

6

7

8

9

Points

1.5

2.5

3.5

4.5

5.5

6.5

7.5

8.5

9.5

10.5

etc

Out of

2

3

4

5

6

7

8

9

10

11

etc

Points

1

1.5

2

2.5

3

3.5

Out of

2

3, 4, 5

etc

4, 5, 6

etc

4, 5, 6

etc

5, 6, 7

etc

5, 6, 7

etc

Points

0.5

Out of

1, 2, 3

etc

Points

0

Out of

1, 2, 3

etc

328

10

11

etc

10

11

etc

4

4.5

5

5.5

6

6.5

etc

6, 7, 8

etc

6, 7, 8

etc

7, 8, 9

etc

7, 8, 9

etc

8, 9, 10

etc

8, 9 10

etc

SCORE:

Students

’ ability

to

analyse

a

problem

and

produce

a

solution,

taking

into

account

crucial

factors

in a

systemat

ic

approac

h

towards

the

solution.

Considere

d all

crucial

factors

Considered most

crucial factors

Considered some

crucial factors

Considered one

crucial factor

Considered no

crucial factors

5 4 3 2 1

Full mark

allocation

Full mark allocation Full mark allocation Full mark allocation Full mark allocation

Point

s

1

2

3

4

5

6

7

8

9

10

11

etc

Ou

t

of

1

2

3

4

5

6

7

8

9

10

11

etc

Points

2

3

4

5

6

7

8

9

10

etc

Out of

3

4

5

6

7

8

9

10

11

etc

Points

1

2

3

4

5

6

etc

Out of

2

4, 5, 6

etc

5, 6, 7

etc

6, 7, 8

etc

7, 8, 9

etc

8, 9, 10

etc

Points

1

Out of

3, 4, 5

etc

Points

0

Out of

1, 2, 3

etc

Halve

mark

allocation

Halve mark

allocation

Halve mark

allocation

Halve mark

allocation

Halve mark

allocation

Point

s

Ou

t

of

Points

1.5

2.5

Out of

2

3

Points

1

1.5

Out of

2

3, 4, 5

Points

0.5

Out of

1, 2, 3

etc

Points

0

Out of

1, 2, 3

etc

329

1

2

3

4

5

6

7

8

9

10

11

etc

1

2

3

4

5

6

7

8

9

10

11

etc

3.5

4.5

5.5

6.5

7.5

8.5

9.5

10.5

etc

4

5

6

7

8

9

10

11

etc

2

2.5

3

3.5

4

4.5

5

5.5

6

6.5

etc

etc

4, 5, 6

etc

4, 5, 6

etc

5, 6, 7

etc

5, 6, 7

etc

6, 7, 8

etc

6, 7, 8

etc

7, 8, 9

etc

7, 8, 9

etc

8, 9, 10

etc

8, 9 10

etc

SCORE:

330

Appendix 10 – KPIs for measuring achievement of outcomes of oral test 1



THERMODYNAMICS 2


EXAMINER: C LOUW

Student No:__________________

MARKS:

Surname:____________________

KPI MEASUREMENT RESEARCH GROUP MAY2010

ORAL TEST NO.: __ QUESTION No.:__


Students’ ability

to

explain/discuss;

the operation of

a system,

components or

parts of a

system in MTHE

2, components

function in the

overall plant

which it forms

part of,

treatment and

Explanation of

operations

clear and

correct

Minor errors in

understanding

unit operations

but overall

correct

A number of errors

in understanding

unit operations

Major errors in

understanding of

unit operations

Explanation of

unit operation

completely

incorrect

5 4 3 2 1

Points

1

2

3

4

5

6

7

Out of

1

2

3

4

5

6

7

Points

1.5

2.5

3.5

4.5

5.5

6.5

7.5

Out of

2

3

4

5

6

7

8

Points

1

1.5

2

2.5

Out of

2

3, 4, 5

etc

4, 5, 6

etc

4, 5, 6

etc

Points

0.5

Out of

1, 2, 3

etc

Points

0

Out of

1, 2, 3

etc

331

maintenance

procedures in

specific

components.

8

9

10

11

etc

8

9

10

11

etc

8.5

9.5

10.5

etc

9

10

11

etc

3

3.5

4

4.5

5

5.5

6

6.5

etc

5, 6, 7

etc

5, 6, 7

etc

6, 7, 8

etc

6, 7, 8

etc

7, 8, 9

etc

7, 8, 9

etc

8, 9, 10

etc

8, 9, 10

etc

Excellent

understanding

of units

function in

overall plant

operations

Minor

misconceptions

in units

function in

overall plant

operations

Some

misunderstandings

with regard to units

function in overall

plant operations

Major

misunderstandings

with regard to units

function in overall

plant operations

No clear

understanding

of units

function in

overall plant

operations

5 4 3 2 1

Points

1

2

3

4

5

6

7

8

9

10

11

etc

Out of

1

2

3

4

5

6

7

8

9

10

11

etc

Points

1.5

2.5

3.5

4.5

5.5

6.5

7.5

8.5

9.5

10.5

etc

Out of

2

3

4

5

6

7

8

9

10

11

etc

Points

1

1.5

2

2.5

3

3.5

4

4.5

5

5.5

Out of

2

3, 4, 5

etc

4, 5, 6

etc

4, 5, 6

etc

5, 6, 7

etc

5, 6, 7

etc

6, 7, 8

etc

6, 7, 8

etc

7, 8, 9

etc

7, 8, 9

etc

Points

0.5

Out of

1, 2, 3

etc

Points

0

Out of

1, 2, 3

etc

332

6

6.5

etc

8, 9, 10

etc

8, 9, 10

etc

SCORE:

Students’ ability

to perform

technical

discussions on

MTHE 2 topics,

communicates

fluently,

explains and

demonstrates

concepts

effectively in

MTHE 2.

Completely

able to

discuss,

demonstrate

or explain

MTHE 2 topics

clearly

Minor problems

in discussion,

demonstration

or explanation

of MTHE 2

topics clearly

Considerable

problems in

discussion,

demonstration or

explanation of

MTHE 2 topics

clearly

Major problems in

discussion,

demonstration or

explanation of

MTHE 2 topics

clearly

Unable to

discuss,

demonstrate

or explain

MTHE 2 topics

clearly

5 4 3 2 1

Points

1

2

3

4

5

6

7

8

9

10

11

etc

Out of

1

2

3

4

5

6

7

8

9

10

11

etc

Points

1.5

2.5

3.5

4.5

5.5

6.5

7.5

8.5

9.5

10.5

etc

Out of

2

3

4

5

6

7

8

9

10

11

etc

Points

1

1.5

2

2.5

3

3.5

4

4.5

5

5.5

6

6.5

etc

Out of

2

3, 4, 5

etc

4, 5, 6

etc

4, 5, 6

etc

5, 6, 7

etc

5, 6, 7

etc

6, 7, 8

etc

6, 7, 8

etc

7, 8, 9

etc

7, 8, 9

etc

8, 9, 10

etc

8, 9, 10

etc

Points

0.5

Out of

1, 2, 3

etc

Points

0

Out of

1, 2, 3

etc

SCORE:

333

Appendix 11 – KPIs for measuring achievement of outcomes of final

examination



THERMODYNAMICS 2


EXAMINER: C LOUW

Student No:__________________

Surname:____________________

KPI MEASUREMENT RESEARCH GROUP 2010

FINAL EXAMINATION: _ QUESTION No.:__


Students

’ ability

to apply

MTHE 2

principle

s to

analyse

and

solve the

problem

accuratel

y.

Analysis

completely

correct

Minor

misinterpretations

(explanation,

discussion,

definition)

Student made a

single error

Some

misinterpretations

(explanation,

discussion,

definition)

Student made more

than one error

Points values are

indicated correctly

on graph but graph

is incorrect or

partially correct

Major

misinterpretations

(explanation,

discussion,

definition)

Student have one

correct statement

Graph/sketch does

not correspond with

interpretation

Analysis completely

incorrect

334

5 4 3 2 1

Point

s

1

2

3

4

5

6

7

8

9

10

11

etc

Ou

t

of

1

2

3

4

5

6

7

8

9

10

11

etc

Points

1.5

2.5

3.5

4.5

5.5

6.5

7.5

8.5

9.5

10.5

etc

Out of

2

3

4

5

6

7

8

9

10

11

etc

Points

1

1.5

2

2.5

3

3.5

4

4.5

5

5.5

6

6.5

etc

Out of

2

3, 4, 5

etc

4, 5, 6

etc

4, 5, 6

etc

5, 6, 7

etc

5, 6, 7

etc

6, 7, 8

etc

6, 7, 8

etc

7, 8, 9

etc

7, 8, 9

etc

8, 9, 10

etc

8, 9, 10

etc

Points

0.5

Out of

1, 2, 3

etc

Points

0

Out of

1, 2, 3

etc

Analytical

solution

completely

correct

Minor


tion errors

Student made one

error

Some


tion errors

Student made more

than one error

Major


tion errors

Student have one

correct


tion

Completely

incorrect


tion

5 4 3 2 1

Point

s

1

2

3

4

5

6

Ou

t

of

1

2

3

4

5

6

Points

1.5

2.5

3.5

4.5

5.5

6.5

7.5

8.5

Out of

2

3

4

5

6

7

8

9

Points

1

1.5

2

2.5

3

Out of

2

3, 4, 5

etc

4, 5, 6

etc

4, 5, 6

etc

5, 6, 7

Points

0.5

Out of

1, 2, 3

etc

Points

0

Out of

1, 2, 3

etc

335

7

8

9

10

11

etc

7

8

9

10

11

etc

9.5

10.5

etc

10

11

etc

3.5

4

4.5

5

5.5

6

6.5

etc

etc

5, 6, 7

etc

6, 7, 8

etc

6, 7, 8

etc

7, 8, 9

etc

7, 8, 9

etc

8, 9, 10

etc

8, 9, 10

etc

SCORE:

Students

’ ability

to

analyse

a

problem

and

produce

a

solution,

taking

into

account

crucial

factors

in a

systemat

ic

approac

h

towards

Considere

d all

crucial

factors

Considered most

crucial factors

Considered some

crucial factors

Considered one

crucial factor

Considered no

crucial factors

5 4 3 2 1

336

the

solution.

SCORE:

337

Appendix 12 – Louw’s Guided Enquiry Based Learning Guide for assisting

students’ learning

A guide to learn and understand

THERMODYNAMICS 2

C LOUW

?

338

Contents

Background……………………………………………………………………….……………..5

Chapter 1………………………………………………………………………...................6

Introduction to Thermodynamics……………………………………………….…......6

Non-flow processes…………………………………………………………………………..8

Example 1………………………………………………………………………………………..8

More relevant questions on this section…………………………………………….10

Exercise 1………………………………………………………………………………………16

Tutorial………………………………………………………………………………………….17

Chapter 2 - Flow processes - Example 1…………………..……………………….23

More relevant questions on this section…………………………………………….25

Exercise 2………………………………………………………………………………………30

Tutorial……………………………………………………………………………………….…31

Chapter 3 – Steam - Example 1…………………………...……………………….…35

More relevant questions on this section……………………………………………40

Exercise 3……………………………………………………………………………………...43

Tutorial……………………………………………………………………………………….…46

Chapter 4 - Throttling of steam - Example 1…………………………………….52

More relevant questions on this section…………………………………………..54

Exercise 4……………………………………………………………………………………..59

Tutorial…………………………………………………………………………………………60

Chapter 5 - Boiler and steam plant - Example 1…………………………….…64

Boiler plant flow diagram……………………………………………………………...64a

More relevant questions on this section…………………………………………..67

Exercise 5.1.…………………………………………………………………………………72

Tutorial………………………………………………………………………………………..74

339

Rankine cycle - Example 2……………………………………………………………..80

More relevant questions on this section……………………………………….…83

Exercise 5.2………………………………………………………………………………...86

Tutorial……………………………………………………………………………………….88

Chapter 6 – Condensers - Example 1…………………………………………..…92

Surface condenser diagrams……………………………………………………....92a

More relevant questions on this section………………………………………...95

Exercise 6………………………………………………………………………….........100

Tutorial……………………………………………………………………………..........101

Chapter 7 – Combustion - Example 1…………………………………………..107

More relevant questions on this section……………………………………….111

Exercise 7……………………………………………………………………………......117

Tutorial…………………………………………………………………………….........118

Revision Exercise……………………………………………………………………….123

340

Nomenclature

A area (m2)

A/F air fuel ratio

c velocity (m/s)

Cp specific heat capacity at constant pressure (kJ/kgK)

Cv specific heat capacity at constant volume (kJ/kgK)

CV calorific value (kJ/kg, MJ/kg)

EE equivalent evaporation from and at 1000C (kg steam/kg fuel)

h enthalpy (kJ)

h specific enthalpy (kJ/kg)

h1 specific enthalpy of steam leaving the boiler plant (kJ/kg)

h0 specific enthalpy of water entering the boiler plant (kJ/kg)

hsup superheated steam specific enthalpy (kJ/kg)

hg saturated steam specific enthalpy (kJ/kg)

hfg specific latent heat of vaporization (kJ/kg)

hf saturated liquid specific enthalpy (kJ/kg)

KE kinetic energy (kJ/kg)

M Molar mass (kg/kmol)

m mass (kg)

ma minimum mass of air (kg)

me excess air mass (kg)

mf mass of fuel (kg)

mS mass of steam or condensate (kg)

mT total mass of air (kg)

mW mass of water (kg)

nT number of tubes

P pressure (kPa, MPa, bar)

Pa partial pressure of the dry air (kPa)

341

Pc condenser pressure (kPa, mmHg)

Pv partial pressure of the vapour (kPa)

PE potential energy (kJ/kg)

POC products of combustion

Q heat flow (kJ)

Ro universal gas constant (kJ/kgK)

R gas constant (kJ/kgK)

rW work ratio

Ssc specific steam consumption (kg/kWhr)

T temperature (0C, K)

TF superheated temperature (0C, K)

Tk temperature of condensate (0C, K)

TS saturation temperature (0C, K)

tw temperature of cooling water (0C, K)

u internal energy (kJ)

u change in internal energy (kJ)

U overall heat transfer coefficient (kW/m2 0C)

V volume (m3)

Va volume of air (m3)

Vg specific volume of dry saturated vapour (m3/kg)

Vs specific volume (m3/kg)

WD work done (kJ)

WDT turbine specific work done (kJ/kg)

x dryness fraction

x0 dryness fraction of steam in separating calorimeter

x1 dryness fraction of steam in throttling calorimeter

efficiency (%)

R Rankine efficiency (%)

density (m3/kg)

342

Background

The purpose of this guide is to help engineering learners to solve problems using the

Enquiry Based Learning (EBL) approach. To be able to solve a problem, one needs to

understand the process or system’s operations in question completely. Questions must

be asked to guide the learner through an information gathering process relevant to the

process or system under discussion. Answers to these questions can be found only if

the learner is actively involved in the learning process i.e. if action is taken to find

answers to these questions and learn how the process or system functions. Reference

material listed at the end of the study guides, text books, websites, papers or journals

can be used to gather information. Each problem has a specific solution or in some

cases more than one. The questions asked must be structured such that with every

answer of a question asked, the solution is a step closer. This process might seem very

time consuming at first, but with more practice and more knowledge gained in a

particular field, the skill to ask goal-directed questions will be developed.

The type of examples used is aimed at first year second semester students (S2) and

based on the fact that these learners has completed their first semester in engineering

and has therefore been exposed to background, terms and expressions used. Only one

example per chapter is given with a guide as to how to go through the process of

asking questions in order for the learner to gain more information about the problem

and to understand it completely so that a solution can be developed. At the end of each

example more relevant questions pertaining to the section under study are given with

answers for further assistance. The content of this guide should be regarded as merely

a support document to learners to learn Thermodynamics 2.

Develop an enquiry mind – solve problems by asking questions – BE ACTIVE!

Ask questions pertaining to the problem. On each question asked you must ‘ACT’, by

343

this I mean you must read, investigate and search to find an answer to the question.

This will guide you through the process of gathering information and learning. This will

enable you to learn more about the problem understand the problem and eventually

solve it. Questions with no action from the learner results in no knowledge gained. The

information in this guide will only be of help if the learner is actively involved in the

learning process. Ask until you understand the problem completely only then can you

effectively solve it. Initially this may take some time, until you have developed the skill

to read a question, define the problem and ask specific questions to guide you

effectively to the solution (depending on the complexity of the problem this may only

take a few seconds):

Example of relevant questions: Examples of irrelevant questions:

What is the process under discussion? Who set the question?

How does this process work? Why is this question asked?

What is the working fluid in the process? What colour is the equipment?

344

CHAPTER 1

Introduction to Thermodynamics

Terms and Definitions

1. Units

Heat - Joules = J = Nm

Pressure = Pascals or kilo-pascals or bar

1bar = 100kPa

1kPa = 1000 Pa

Temperature = Kelvin or Degrees Celsius

Kelvin (K) = Degrees Celsius (oC) + 273

Degrees Celsius (oC) = Kelvin (K) + 273

S.T.P. = standard temperature and pressure = 101,3kPa and 273 K

Volume = m3 specific volume = m3/kg

2. Specific heat capacity (C) [kJ/kgK]

Def.: The specific heat capacity of an object is the amount of thermal energy required

to give a unit mass of the object a unit temperature rise.

Eg. C of water is 4,187kJ/kgK

2.1 Specific heat capacity at constant volume (Cv) [kJ/kgK]:

It is the amount of thermal energy required to give a unit mass of the gas by one

degree, with the volume remaining constant.

345

2.2 Specific heat capacity at constant pressure (Cp) [kJ/kgK]:

It is the amount of thermal energy required to give a unit mass of the gas by one

degree, with the pressure remaining constant.

3. Gas laws

3.1 Boyle’s law

Boyle found by means of an experiment that the volume of a mass of gas is inversely

proportional to the pressure on it, if the temperature remains constant.

PV = c or P1V1 = P2V2 = P3V3 ….

3.2 Charles’ law

Charles found by means of an experiment that the volume of a mass of gas, at constant pressure, changes by 1/273 of its volume at 00C for every degree change in temperature.

V/T = c or V1/T1 = V2/T2 = V3/T3 … 3.3 Combined or general law

A combination of the previous laws, results in: PV/T = c or P1V1/T1 = P2V2/T2 = P3V3/T3 …

3.4 Gas constant (R)

The universal gas constant Ro has a value 8,314 kJ/kgK

346

Each gas has its own gas constant R value determined as follows:

R = Ro/M R = gas constant in kJ/kgK M = molar mass of the gas in (kg/kmol)

3.5 Characteristic gas constant

According to Boyle and Charles PV/T = c and c = mR

This equation becomes then: PV/T = mR PV = mRT where m is the mass of gas in kilogram

3.6 First law of Thermodynamics

This law basically states that energy cannot be created or destroyed, but can only be changed from on form to another. For a non-flow process: heat gained or lost = work done + change in internal energy of the gas Q = WD +Δu U is the symbol for the internal energy of an ideal gas and is mainly determent by the temperature of the gas. Internal energy is also a point function and is independent of the rout followed to get from one point to another. For this reason is the change in internal energy always calculate with the next formula: Δu = mCv(T2 – T1)

347

Non-flow processes

Example 1

Oxygen is heated up in a sealed container. The original pressure was 10kPa and the final pressure is 100kPa. The container has an inside diameter of 0.3m and an internal height of 0.5m. The temperature at the beginning of the process was 1100C. Take the molecular mass of oxygen as 32. Determine: 1.1 the mass of oxygen in the container; 1.2 the final temperature of the oxygen. 1.1 Questions to ask in order for me to understand the problem and to come up

with a solution:

Q: what process is this? A: a heating process

Q: what type of heating process is it if it takes place inside a container? A: a constant volume heating process and because the process takes place inside a

sealed container, which means the gas is trapped inside the container it is therefore also a non-flow process.

Q: what exactly is a constant volume process? A: it is a process that takes place such that the volume remains unchanged during

the duration of the process, but the temperature and pressure changes, these changes in temperature causes the gas to expand or contract due to more or less rapid movement of the molecules, this in turn results in an increase or decrease in pressure.

Q: can this process be illustrated on a diagram? A: yes. A pressure volume diagram can be used to show the relationship between

the pressure, volume and temperature at the various points in the process.

348

P T2 P2 2 T1 P1 1 V1 = V2 V Q: what is the relationship between pressure, volume and temperature during this

process? A: P1V1/T1 = P2V2/T2 but V1 = V2

» P1/T1 = P2/T2

Q: what type of gas is oxygen? A: it is a perfect gas, so the characteristic equation applies:

PV = mRT Q: The mass of the oxygen must be calculated. Which formulas contain mass that

can be a posseble option? A: PV = mRT Δu = mCv(T2 – T1) Q: can the first equation be used? A: yes, because in P1V1 = mRT1 the unknowns are m and R, but R can be solved by

using the universal gas constant equation R = Ro/M R = Ro/M R = 8.314/32 = 0.2598kJ/kgK 10 * π/4 * 0.32 * 0.5 = m * 0.2598 * (110 + 273)

349

m = 3.55 *10-3 kg → answer Q: can the second equation be used? A: no, because Δu, Cv and T2 are unknown. 1.2 Q: Determine the final temperature T2 of the gas. Which formulas contain T2 that

can give a posseble solution? A: P2V2 = mRT2 it is a constant volume process therefore V1=V2 and hence

everything is known except T2 and it can be solved: 100 * π/4 * 0.32 * 0.5 = 3.55 *10-3 * 0.2598 * T2

T2 = 3832.08 K → answer

P1/T1 = P2/T2 this is the most straight forward solution to the question, because everything is known except T2:

10/383 = 100/T2

T2 = 3830 K → answer Δu = mCv(T2 – T1) this equation also contains T2, but Cv and Δu are unknown. Cv can be calculated but not Δu and therefore this will not be an option. More relevant questions and answers on this section Q: What are the different types of non-flow processes? A: Constant volume process (CVP), constant pressure process (CPP), isothermal process (IP), adiabatic process (AP), polytropic process (PP). Q: What is the relationship between pressure, volume and temperature for each process? A: CVP: P1/T1 = P2/T2 CPP: V1/T1 = V2/T2

IP: P1V1 = P2V2 AP: P1V1 = P2V2

PP: P1V1

n = P2V2n

Q: What is and n? A: is the adiabatic index of compression or expansion and can be determined

350

from the relationship of the specific heat capacities of the gas: = Cp/Cv

n is the polytropic index of compression or expansion: n ≠ Cp/Cv Q: What are the characteristics of each of these processes? A: CVP volume remains constant throughout the process no work is done during this process CPP pressure remains constant throughout the process IP temperature remains constant throughout the process all heat flow to the system or away from the system is equal to the work done on or by the gas AP no heat flow across the boundary of the system this process takes place on a constant entropy line PP during this process all state point values change, work is done on or by the gas, heat flow to or away from the system and the internal energy of the gas increase or decrease Q: Where are they used or applied in practice? A: CVP heating or cooling of a gas in a pressure vessel CPP heating or cooling of a gas in a cylinder with a frictionless piston

IP compression or expansion of a gas (work done on or by the gas) in a cylinder such that temperature stays unchanged e.g. heat engines

AP compression or expansion of a gas (work done on or by the gas) without any heat flow e.g. a diesel engine PP compression or expansion of gas (work done on or by the gas) where heat flow to or away from the system e.g. air compressor Q: What are the relevant formulas for each of these processes i.e. how is heat flow (Q), work done (WD), change in internal energy (Δu) and enthalpy (h)

351

calculated for each one? (The derivations of these formulas are left to the learner to investigate)

A: CVP Q = WD + Δu WD = ∫PdV = 0 Δu = mCv(T2 – T1) h = PV + u _______________________________________________________________ CPP Q = WD + Δu WD = ∫PdV = P(V2 – V1) = mR(T2 – T1) Δu = mCv(T2 – T1) h = PV + u _______________________________________________________________ IP Q = WD + Δu WD = ∫PdV = PVln r = mRTlnr

Δu = mCv(T2 – T1) h = PV + u _______________________________________________________________

AP Q = WD + Δu WD = ∫PdV

(P1V1 – P2V2) =------------------ γ - 1 mR(T1 – T2) =------------------ γ - 1

Δu = mCv(T2 – T1) h = PV + u _______________________________________________________________

PP Q = WD + Δu WD = ∫PdV (P1V1 – P2V2)

=------------------ n - 1 mR(T1 – T2) = ----------------- n - 1

352

Δu = mCv(T2 – T1) h = PV + u

Q: How is each one illustrated on a pressure volume diagram? A: CVP P 1 B 1 – 2 cooling A – B heating

2 A

V CPP P 1 2 1 – 2 heating B A A – B cooling

WD V

IP P B 1 1 – 2 expansion A – B compression 2 WD A

V AP P 2 A 1 – 2 compression A – B expansion B

WD 1 V

PP P 2 A 1 – 2 compression A – B expansion B

WD 1 V

353

Exercise 1

1.1 A mass of 1.2kg of air at 150kPa and 120C is contained in a gas-tight, frictionless piston-cylinder device. The air is now compressed to a final pressure of 600kPa. During the process heat is transferred from the air such that the temperature inside the cylinder remains constant. Calculate the work done during this process. (-136kJ)

1.2 A student living in a 4m x 6m x 6m dormitory room turns on her 150W fan

before she leaves the room on a summer day, hoping that the room will be cooler when she comes back in the evening. Assuming all the doors and windows are tightly closed and disregarding any heat transfer through the walls and windows, determine the temperature in the room when she comes back 10hrs later. Assuming the room to be at 100kPa and 150C when she leaves. (58.20C)

1.3 A piston device contains 0.1m3 of air at 400kPa and 500C. Heat is transferred

to the air in the amount of 40kJ as the air expands isothermally. Determine the amount of boundary work done during this process. (40kJ)

1.4 A piston-cylinder device whose piston is resting on a set of stops, initially

contains 3kg of air at 200kPa and 270C. The mass of the piston is such that a pressure of 400kPa is required to move it. Heat is now transferred to the air until its volume doubles. Determine:

1.4.1 the work done by the air; (516kJ) 1.4.2 the total heat transferred to the air during this process. (2674kJ)

1.5 A piston-cylinder device, with a set of stops on the top, initially contains 3kg

of air at 200kPa and 270C. Heat is now transferred to the air, and the piston rises until it hits the stops, at which point the volume is twice the initial volume. More heat is transferred until the pressure inside the cylinder also doubles. Determine:

1.5.1 the work done; 1.5.2 the amount of heat transfer for this process.

1.6 A certain gas has a density of 1.925kg/m3 at 101.3kPa and 160C.

1.6.1 Calculate the gas constant ’R’. (0.182kJ/kgK)

If 0.86kg of this gas is heated from 160C to 2550C, at constant pressure,

354

205.54kJ is needed. Calculate:

1.6.2 the specific heat capacity at constant pressure; (1kJ/kgK) 1.6.3 the specific heat capacity at constant volume; (0.818kJ/kgK) 1.6.4 the total work done. (37.4kJ)

1.7 A quantity of gas is compressed from 103.5kPa and a volume of 0.12m3 to a

temperature of 1170C. The original temperature of the gas was 190C and 3.85kJ heat was rejected to the atmosphere during the process. Take R = 0.228kJ/kgK, Cp = 0.92kJ/kgK and calculate:

1.7.1 the value of the index of compression; (n = 1.252) 1.7.2 the final pressure. (435.87kPa)

Tutorial

1.1 A mass of 1.2kg of air at 150kPa and 120C is contained in a gas-tight,

frictionless piston-cylinder device. The air is now compressed to a final pressure of 600kPa. During the process heat is transferred from the air such that the temperature inside the cylinder remains constant. Calculate the work done during this process. (-136kJ)

Questions relevant to understand and solve this problem: Is this a flow or non-flow process? What initial and final information is given in the question? Is there any relationship between these values during the execution of the process? If the air is compressed in this cylinder device, what happens to the pressure, volume and temperature and which processes are included or eliminated by this? What is the relationship between pressure, volume and temperature for this process? By answering the above questions, you will be able to identify the process. You can now apply all the formulas pertaining to this process to find the answer. You can also draw the process on a pressure-volume diagram and indicate the area which represents the work done. The following steps are suggested for drawing the diagram:

1. Identify the process in the question – in this case it is a constant temperature (isothermal) process.

355

2. Draw the p-v axis and the constant temperature curve. 3. Remember that the process must stay on the isothermal curve and

movement between the initial and final point is restricted to this line. 4. Now the type of isothermal process must be identified – in this case it is a

compression process. 5. During compression the volume decreases and the pressure increases. 6. To be able to reflect this on the isothermal curve, make a point ‘1’ at the

lower right hand side and then move up with the curve to a position higher which will be point ‘2’.

7. Draw vertical dotted lines from these points to the volume axis. 8. The enclosed area under the graph represents the work done the gas during

the process.

NOTE: This systematic approach can be applied to all processes and even to problems consisting of more than one process. In a case where there are more than one process involved, remember that the end point of the first process is the starting point of the second process and so on.

Find answers to these questions and use them as a guide to solve this problem. You can add more questions if necessary. Apply the same approach to the remaining questions in the exercise.

356

Chapter 2

Flow processes

Example 1

Air flows through a compressor with an initial velocity of 10m/s and an exit velocity of 100 m/s. At inlet the air has a pressure of 100kPa and a specific volume 0.83m3/kg. The exit pressure is 200kPa and the specific volume 0.66m3/kg. During is passage through the compressor, the internal energy is increased by 100kJ/kg. Calculate the heat flow to or away from the compressor if it requires 25kW to compress the air at a flow rate of 2kg/s. Q: what is a flow process? A: it is a process whereby the fluid undergoing the process crosses the boundaries

of the system. Units through which flow processes occurs are: pipelines, heat exchangers, nozzles, condensers, compressors and turbines. During a flow process the fluid will enter the system at a specific monitoring point with specific values with regard to its velocity, pressure, specific volume, temperature and flow rate. The fluid will leave the system at another monitoring point with different values except for the mass flow rate. The mass flow rate will be constant measured at any state and therefore these processes are referred to as steady state flow processes.

Q: what is an air compressor and how does it function? A: air compressors are devices that compress the air entering the unit to a higher

pressure according to its application. Different compressors are widely used and can be classified as radial flow, axial flow, screw and positive displacement units.

Q: what are the relationships between the inlet and outlet conditions and how can

this be expressed in terms of an equation? A: draw up an energy balance across the compressor. This is an equation which

states that all energy entering the compressor must be equal to all energy leaving the unit. This is based on the first law of thermodynamics which states that energy can not be created or destroyed but can only change from one form to another. This equation is as follows:

KE1 + PE1 + P1Vs1 + u1 + Q = KE2 + PE2 + P2Vs2 + u2 + WD KE1 = kinetic energy at inlet, considering a mass flow rate of 1 kg/s = c1

2/2000(kJ/kg)

PE1 = potential energy at inlet, measured from a specific datum line for a mass flow rate of 1 kg/s

357

= gh (kJ/kg)

P1*Vs1 + u1 = this is the total energy or heat value of the fluid and is also referred to as its enthalpy (h)

Q = during the operation of the compressor heat will either flow towards the unit or away from the unit. When it flows away from the unit it is designated by a negative sign. The unit for heat flow can be kJ/kg or kW. KE2 = kinetic energy at outlet, considering a mass flow rate of 1 kg/s = c2

2/2000 (kJ/kg)

PE2 = potential energy at outlet, measured from a specific datum line for a mass flow rate of 1 kg/s

= gh (kJ/kg) Note: due to the small values for potential energy and its influence on

the final answer, it is sometimes omitted from the energy equation. This is however individually evaluated

P2*Vs2 + u2 = this is the total energy or heat value of the fluid and is

also referred to as its enthalpy (h) Note: In the energy equation either enthalpy (h) or the term P*Vs + u is

used WD = during the compression of the fluid work is being done on the fluid and an external source is required to drive the compressor unit. The unit for work done is kJ/kg or kW Q: there is no specific value given for the internal energy at inlet or outlet, how are these two unknowns dealt with in a single equation? A: in some cases specific values are not necessary, but merely a relationship of what happens between inlet and outlet with regard to that specific property. In this specific case the internal energy is increased a 100 kJ/kg and this gives the following relationship: u2 = u1 + 100 Q: can all the values be substituted into the energy equation? A: Make sure that all the variables in the equation are in the same units i.e. kJ/kg or kW. In this particular problem the power generated by the compressor is given in kW and all other variables are in kJ/kg, therefore the power must be converted into kJ/kg.

358

Q: how is kW converted into kJ/kg? A: in this problem mass flow is also given in kg/s: kW = kJ/s

kJ/kg = kJ/s * s/kg i.e. power in kW is simply divided by the given mass flow in kg/s to convert it to kJ/kg

Q: calculate the heat flow to or away from the compressor A: substitute and solve for Q:

102/2000 + 100*0.83 + u1 + Q = 1002/2000 + 200*0.66 + u1 + 100 + 25/2

Q = 166.45 kJ/kg → answer

Q: is the heat flowing to or away from the compressor? A: the compressor is driven by an external source such as an electric motor and therefore it is doing work on the air. Compressing the air will generate friction within the air molecules and also friction between the cylinder and piston surfaces during the up and downward motion. This friction will cause the temperature of the air and that of the compressor to rise above that of the surrounding air. Therefore heat will flow from the compressor (high temperature) to surrounding air (low temperature). → answer More relevant questions on this section Q: What is the relationship between the mass flow rate at inlet and the mass flow rate at outlet? A: m1 = m2 and the unit is kg/s Q: How can this mass flow rate be calculated? A: m1 = c1A1/Vs1 = m2 = c2A2/Vs2

Q: Which factors affect the mass flow rate? A: The diameter (cross sectional area) of the inlet and outlet pipes The velocity at inlet and outlet The specific volume of the fluid at inlet and outlet Q: What are the characteristics of the other units operating on a flow

359

process? A: Pipelines: 1. No work done through a rigid pipe 2. If pipes are perfectly thermally insulated no heat flows Heat exchangers: The purpose of these units is to transfer heat No work done Nozzles: 1. The purpose of this device is to accelerate the fluid as the pressure drop No work done 2. If the nozzles is perfectly thermally insulated no heat flows 3. If inlet velocity is small it can be neglected (c < 70m/s) Diffusers: 1. The purpose of this device is to retard the fluid velocity No work done 2. If the diffuser is perfectly thermally insulated no heat flows 3. If exit velocity is small it can be neglected Condensers: The purpose of these units is to remove heat from hot fluid No work done Compressors: 1. The purpose of this device is to increase the pressure of the fluid by means of mechanical work 2. If the compression is adiabatic no heat flows Turbines: The purpose of this device is to utilize the kinetic energy of the fluid flowing through it to develop mechanical power on the output shaft Q: How does this affect the steady flow energy equation? A: Pipelines: 1. KE1 + PE1 + P1Vs1 + u1 + Q = KE2 + PE2 + P2Vs2 + u2 2. KE1 + PE1 + P1Vs1 + u1 = KE2 + PE2 + P2Vs2 + u2 Heat exchangers: KE1 + PE1 + P1Vs1 + u1 + Q = KE2 + PE2 + P2Vs2 + u2 Nozzles: 1. KE1 + PE1 + P1Vs1 + u1 + Q = KE2 + PE2 + P2Vs2 + u2 2. KE1 + PE1 + P1Vs1 + u1 = KE2 + PE2 + P2Vs2 + u2

360

3. PE1 + P1Vs1 + u1 + Q = KE2 + PE2 + P2Vs2 + u2 + WD Diffusers: 1. KE1 + PE1 + P1Vs1 + u1 + Q = KE2 + PE2 + P2Vs2 + u2 2. KE1 + PE1 + P1Vs1 + u1 = KE2 + PE2 + P2Vs2 + u2

3. KE1 + PE1 + P1Vs1 + u1 + Q = PE2 + P2Vs2 + u2 + WD Condensers: KE1 + PE1 + P1Vs1 + u1 + Q = KE2 + PE2 + P2Vs2 + u2 Compressors: 1. KE1 + PE1 + P1Vs1 + u1 + Q = KE2 + PE2 + P2Vs2 + u2

+ WD 2. KE1 + PE1 + P1Vs1 + u1 = KE2 + PE2 + P2Vs2 + u2 + WD Turbines: KE1 + PE1 + P1Vs1 + u1 + Q = KE2 + PE2 + P2Vs2 + u2 + WD Q: When the fluid undergoing the flow process is not a perfect gas e.g. steam, how are the properties at inlet and outlet calculated? A: For steam the inlet pressure, volume and temperature will be used to determine the condition from steam table or the Mollier chart. The approach for outlet will be the same using outlet values.

361

Exercise 2

2.1 Air enters an adiabatic nozzle steadily at 300kPa, 2000C, and 30m/s and

leaves at 100kPa and 180m/s. The inlet area of the nozzle is 80cm2. Determine:

2.1.1 the mass flow rate through the nozzle; (0.5304kg/s) 2.1.2 the exit temperature of the air; (184.60C) 2.1.3 the exit area of the nozzle. (38.7cm2)

2.2 Air enters a nozzle steadily at 300kPa, 770C, and 50m/s and leaves at

100kPa and 320m/s. The heat loss from the nozzle is estimated to be 3.2kJ/kg of air flowing. The inlet area of the nozzle is 100cm2. Determine:

2.2.1 the exit temperature of air; (24.20C) 2.2.2 the exit area of the nozzle.(39.7cm2)

2.3 Air at 600kPa and 4000C enters an adiabatic nozzle that has an inlet-to-exit

area ratio of 2:1 with a velocity of 120m/s and leaves with a velocity of 380m/s. Determine:

2.3.1 the exit temperature; (436.5K) 2.3.2 the exit pressure of the air. (330.8kPa)

2.4 Air at 80kPa and 1270C enters an adiabatic diffuser steadily at a rate of

6000kg/hr and leaves at 100kPa. The velocity of the air stream is decreased from 230m/s to 30m/s as it passes through the diffuser. Find:

2.4.1 the exit temperature of the air; 2.4.2 the exit area of the diffuser.

2.5 Air at 80kPa and -80C enters an adiabatic diffuser steadily with velocity of

200m/s and leaves with a low velocity at a pressure of 95kPa. The exit area of the diffuser is 5 times the inlet area. Determine:

2.5.1 the exit temperature; 2.5.2 the exit velocity of the air.

2.6 Air at 80kPa, 270C, and 220m/s enters a diffuser at a rate of 2.5kg/s and

leaves at 420C. The exit area of the diffuser is 400cm2. The air is estimated to lose heat at a rate of 18kJ/s during this process. Determine:

2.6.1 the exit velocity; (62m/s)

362

2.6.2 the exit pressure of the air. (91.1kPa) 2.7 Air flows steadily through an adiabatic turbine, entering at 1MPa, 5000C, and

120m/s and leaving at 150kPa, 1500C, and 250m/s. The inlet area of the turbine is 80cm2. Determine:

2.7.1 the mass flow rate of the air; 2.7.2 the power output of the turbine.

2.8 Air enters the compressor of a gas turbine plant at ambient conditions of

100kPa and 250C with a low velocity and exits at 1MPa and 3470C with a velocity of 90m/s. The compressor is cooled at a rate of 1500kJ/min and the power input to the compressor is 250kW.Determine the mass flow rate of air through the compressor. (0.68kg/s)

2.9 Air is compressed from 100kPa and 220C to a pressure of 1MPa while being

cooled at a rate of 16kJ/kg by circulating water through the compressor casing. The volume flow rate of the air at inlet conditions is 150m3/min and the power input to the compressor is 500kW. Determine:

2.9.1 the mass flow rate of the air; (2.95kg/s) 2.9.2 the temperature at the compressor exit. (1740C)

2.10 In a centrifugal compressor air flows steadily at a rate of 2.1kg/s and 81m/s

with a pressure of 90kPa and specific volume of 0.85m3/kg. The exit conditions are: speed 200m/s, pressure 900kPa and specific volume of 0.13m3/kg. The internal energy of the air at exit is 90kJ/kg greater than that of the air at inlet. Heat is lost during compression at a rate of 95kJ/s. Calculate:

2.10.1 the power required to drive the compressor; (404kW) 2.10.2 the diameters of the inlet and outlet pipes. (167.5mm, 41.7mm)

Tutorial

2.1 Air enters an adiabatic nozzle steadily at 300kPa, 2000C, and 30m/s and leaves

at 100kPa and 180m/s. The inlet area of the nozzle is 80cm2. Determine:

2.1.1 the mass flow rate through the nozzle; (0.5304kg/s) 2.1.2 the exit temperature of the air; (184.60C) 2.1.3 the exit area of the nozzle. (38.7cm2)

Questions relevant to understand and solve this problem:

Is this a flow or non-flow process?

363

What is the fluid flowing through the nozzle? What are the inlet and outlet conditions and what information is supplied at these points? What is the process through this nozzle? By answering the above questions, you will be able to identify the process. You can now apply all the formulas pertaining to this process to find the answer. Find answers to these questions and use them as a guide to solve this problem. You can add more questions if necessary. Apply the same approach to the remaining questions in the exercise.

364

Chapter 3

Steam

Example 1

Water at 100kPa and 150C is heated up in a pressure cooker on a stove. The location at which the exercise takes place is at sea level i.e. 100kPa. 1.1 What will be the condition of the steam when the pressure gauge reads 300kPa and 2000C? 1.2 How much heat has been given to the steam? 1.3 Plot the process on a temperature-entropy diagram. 1.1 Questions to be asked in order for one to understand the problem and be able to answer the questions: Q: what is a pressure cooker? A: it is a pressure vessel that allows pressure to build up within it, in order for the temperature to increase so that the food inside the cooker can be cooked faster.

The volume of the cooker remains unchanged during the process. This means that the specific volume of the steam before and after the process is unchanged: Vs1 = Vs2 (m3/kg)

Q: will the pressure cooker not explode at some stage? A: no, because it has safety valves fitted to the lid. These safety valves will open

and ensure that steam is blown once maximum operating pressure is reached. This value is normally indicated on the lid and the bottom of the pot. E.g. a 7l Tedelex pressure cooker has a maximum operating pressure of 80kPa.

Q: why will the food cook faster when the pressure inside the vessel increases? A: there is a direct relationship between pressure and temperature. The more the pressure increases the higher the temperature at which the water will boil. At 100kPa water boils at 990C, if the pressure of the container is increased to 200kPa, the water will only start boiling at 1200C. The temperature at a specific pressure where the water will start boiling is referred to as the saturation temperature and these are the values listed in the steam tables. This higher temperature allows the food to be cooked faster than in the normal pot. Q: what does the term ‘condition of the steam’ mean? A: when dealing with water and steam the condition of the steam refers to the quality of the steam. This means the amount of water and the amount of steam at the particular condition that co-exists in the same container and it is normally expressed in terms of a fraction called the ‘dryness fraction x’. The

365

water and the steam represent different phases. Water represents the liquid phase and steam, the vapour phase. At any pressure water temperature will increase until it reaches the saturation temperature corresponding to that pressure. At this point the water is said to be saturated liquid. If water at atmospheric conditions is heated up it will reach saturation point at sea level (100kPa) at approximately 99.60C. At this point bubbles are forming within the water and any heat addition will start changing some of the water into steam. Now there are two phases in one container and this is referred to as wet steam. The relationship between the amount of liquid and the amount of vapour will determine the condition (dryness fraction) of the steam. Q: how does one find this condition? A: there are steam tables and enthalpy/entropy charts (Mollier charts) available which reflects the relationship between steam at a certain pressure and temperature. From these tables or chart the reading will be taken at 300kPa and 2000C. On the steam tables the following values are listed: Temperature; pressure; specific volume; saturated liquid enthalpy; latent heat of evaporation; saturated vapour enthalpy. For any specific pressure there is a temperature at which water will boil. If the pressure is increased the boiling temperature also increases. At a specific pressure water will reach saturation point when its temperature is raised to the temperature corresponding to the saturation temperature listed in the tables. At this point the enthalpy of the water will be that of saturated liquid (hf). Any more heat supplied to the water will start transforming the water into steam. It will be noted that during this transformation process the temperature of the water remains constant. This is because the heat supplied to the water is used to transform the water from water into steam which is a phase change. This heat is then also called latent heat of vaporization (hfg). Once this phase change process is completed, the steam is said to be saturated vapour (hg) and any further addition of heat will increase the temperature of the steam. The steam will now enter the superheated region and will be referred to as superheated steam and the enthalpy denoted as hsup. Once the temperature of the steam is higher than the saturation temperature listed in the steam tables, then the superheated tables or the Mollier chart must be used to determine the enthalpy, specific volume etc. To answer the question, the saturation temperature corresponding with 300kPa is 133.50C and therefore if the steam temperature is 2000C, it is definitely superheated. → answer 1.2 To be able to answer the second question the following questions need to asked:

366

Q: what was the initial heat value of the water/steam? A: when the process started, the water was at 150C and 100kPa. The total heat value is the enthalpy of the water and it is calculated from: hf = 4.187 * 15 = 62.81kJ/kg or read from the table at hf The final enthalpy of the superheated steam can be read of the superheated steam tables or Mollier chart or calculated if the specific heat capacity for the steam was available: hsup = hg + Cp ( TF – TS); TF = final temperature; TS = saturation temperature; Cp = specific heat capacity at constant pressure. However Cp is not given, therefore the value for hsup is read from the table or chart: hsup = 2866kJ/kg The heat supplied to the steam is therefore the difference between the original and the final heat value of the steam: Heat supplied = final heat - initial heat = hsup - hf

= 2866 – 62.81 = 2803.19kJ/kg → answer 1.3 to be able to answer this question the following questions need to be asked: Q: what is a temperature-entropy diagram? A: it is a diagram with the vertical axis the temperature scale and the horizontal axis the entropy scale. On this diagram there is also a saturation curve (OAB) which indicates the liquid, wet and superheated regions. The line OA represents the saturated liquid line, the point ‘B’ represents the critical point and the line AB represents the saturated vapour line. Different pressure lines are also indicated and run from bottom left to the top right. The curved line indicates the constant volume lines.

367

T (temp) A Volume liquid Pressure wet steam superheated steam hfg hf hg B O s (entropy)

The area under a curve on this diagram will represent the heat flow (Q) during the process. If it is a constant pressure process the process will remain on one pressure line from the start to the end of the process. In the case of the question the process starts at a pressure of 100kPa and end at 200kPa. To be able to plot the process on this diagram some information regarding the initial and end conditions are required. Again a number of questions must be asked: Q: What was the condition of the steam when the process started? A: the steam was pure water at atmospheric pressure; Q: What route did it followed to get to the end point? A: a pressure cooker was used and therefore the specific volume before and after the process remained unchanged. Q: What was the condition of the steam at the end point? A: the temperature of the steam at the end of the process was higher than

the saturation temperature corresponding with the pressure and that means that the steam was superheated.

Now the process can be plotted:

368

T 2 T2 = 2000C Tsat = 120.20C 200kPa V 100kPa Tsat = 990C T1 = 150C 1 s More relevant questions on this section Q: What other non-flow processes can steam be subjected to?

A: Constant volume process (CVP), constant pressure process (CPP), isothermal process (IP), adiabatic process (AP), polytropic process (PP).

Q: What are the relevant relationships between pressure, volume and

369

temperature for these processes?

A: CVP: P1/T1 = P2/T2 CPP: V1/T1 = V2/T2

IP: P1V1 = P2V2 AP: P1V1 = P2V2

PP: P1V1

n = P2V2n

Q: How is the steam’s condition determined at various points of the process?

A: By using any two of the following properties pertaining to the specific point: enthalpy, pressure, specific volume, temperature, dryness fraction and entropy. Note that if the steam is at the saturation temperature, its dryness fraction can be between 0 and 1 and therefore it must be determined exactly.

This information can then be used with the Mollier chart or the steam tables. Q: How is heat flow, work done, change in internal energy and enthalpy during these processes determined? A: CVP Q = WD + Δu WD = 0 Δu = (h2 – h1) – (P2V2 – P1V1) h = PV + u _______________________________________________________________ CPP Q = WD + Δu WD = P(V2 – V1) Δu = (h2 – h1) – (P2V2 – P1V1) h = PV + u _______________________________________________________________ IP Q = WD + Δu Q = T(s2 – s1) Δu = (h2 – h1) – (P2V2 – P1V1) h = PV + u _______________________________________________________________ AP Q = WD + Δu Q = 0 s1 = s2

Δu = (h2 – h1) – (P2V2 – P1V1) h = PV + u

_______________________________________________________________ PP Q = WD + Δu WD (P1V1 – P2V2) = ----------------- n - 1 Δu = (h2 – h1) – (P2V2 – P1V1) h = PV + u

370

Q: How can these processes be illustrates on temperature-entropy and pressure-volume diagrams? A: CVP P T 1 B 1 – 2 cooling 1 B A – B heating

2 2 A A Q

V s _______________________________________________________________ CPP P T 2 A 1 2 1 – 2 heating 1 B A A – B cooling

B Q WD V s

_______________________________________________________________ IP P T P1

1 – 2 expansion P2 1 A – B compression 1 2 B B A 2 Q WD A

V s _______________________________________________________________

AP P T 2 A 1 – 2 compression A – B expansion 2 A B

WD 1 B 1 V s

_______________________________________________________________ PP P T

2 A 1 – 2 compression 2 A A – B expansion 1 B WD B Q

1 V s

371

Note: steam is not a perfect gas and therefore phase changes occur. It is important to identify the initial and final condition of the steam when using the above formulas to ensure that the correct phase is represented when substituting values. Q: What is entropy and what is it used for? A: for the purpose of this course we will only give an introduction to entropy (s). Entropy is a measure of the amount of disorder or the amount of energy which is not available to do work or the amount of energy which can not be converted into work. Entropy is also a point function and is not influenced by the process followed to get to the point. This is also the property which remains constant during an adiabatic process, i.e. an adiabatic process takes place on a constant entropy line. From a engineering point of view the change

in entropy (s) is most of the time of more value than the actual entropy value at a specific point. s = Q/T

s = Q/T

372

Exercise 3

3.1 Determine the specific enthalpy of steam at 600kPa and 0.96 degrees of

dryness. (2671.6kJ/kg) 3.2 At a pressure of 1.5MPa steam has a specific volume of 0.1982m3/kg.

Determine the specific enthalpy and temperature of the steam. (3228kJ/kg, 3900C)

3.3 A closed container with a volume of 0.035m3 contains dry saturated steam at a

pressure of 750kPa. Determine:

3.3.1 the mass of the steam; (0.137kg) 3.3.2 the enthalpy of the steam. (378.8kJ)

3.4 Superheated vapour at 1MPa and 3000C is allowed to cool at constant volume

until the temperature drops to 1500C. At the final state, determine:

3.4.1 the pressure; (475.8kPa) 3.4.2 the quality; (0.656) 3.4.3 the enthalpy. (2019kJ/kg)

3.5 Steam at 7bar, dryness fraction of 0.9, expands reversebly at constant

pressure until the temperature is 2000C. Calculate:

3.5.1 the work input per kilogram of steam; (38.2kJ/kg) 3.5.2 the heat supplied per kilogram of steam. (288.7kJ/kg)

3.6 A quantity of steam at a pressure of 3MPa has a dryness fraction of 0.72. The

steam occupies a volume of 0.4m3. Heat is transferred into the steam while the pressure remains constant until the steam is dry saturated. The steam is then cooled at constant volume until the pressure becomes1.8MPa. Determine:

3.6.1 the heat transferred during the constant pressure process;

(4189.95kJ) 3.6.2 the percentage of heat transfer which appears as work transfer;

(11.4%) 3.6.3 the heat transferred during the constant volume process. (-

5708.44kJ)

3.7 Steam at a pressure of 2MPa and with a temperature of 2500C is expanded to a pressure of 0.4MPa, the law of expansion being PV1.2 = C. After expansion the steam is cooled at constant volume to a pressure of 0.2MPa.

373

Determine:

3.7.1 the condition of the steam after expansion according to the law PV1.2 = C; (0.921)

3.7.2 the heat transfer per kilogram of steam during the expansion; (-91kJ/kg)

3.7.3 the condition of the steam after the constant volume cooling; (0.481)

3.7.4 the heat transferred per kilogram of steam during the constant volume cooling. (-921kJ/kg)

3.8 Determine the enthalpy, volume and density of 4.5kg of steam at a pressure

of 2MPa and with a temperature of 3000C. (13612kJ, 0.5625m3, 7.97kg/m3) 3.9 Determine the specific enthalpy and specific volume of steam at a pressure

of 18bar and with a temperature of 3200C. (3075.16kJ/kg, 0.149m3/kg) 3.10 1kg supply water at 00C is changed at 1.4MPa to wet steam with a dryness

fraction of 0.82. The wet steam is heated still further, at constant pressure, to a final volume of 0.1568m3. Calculate:

3.10.1 the work done to form super heated steam from wet steam;

(58kJ/kg) 3.10.2 the heat supplied to form super heated steam from wet steam.

(455.7kJ/kg) 3.11 5220kJ of heat is required to form 2kg wet steam at 1.3MPa from supply

water at 290C. The wet steam is heated still further, at constant pressure, until the final temperature is 2500C. Calculate:

3.11.1 the work done to form super heated steam from wet steam;

(38.74kJ/kg) 3.11.2 the heat supplied to form super heated steam from wet steam.

(204kJ/kg) 3.12 Steam at 500kPa and 2500C expands isentropically to a pressure of 70kPa.

Using the Mollier chart, determine the dryness fraction of the steam. (0.96)

3.13 Steam at 1400kPa and 2160C expands isentropically to a pressure of 100kPa. Calculate the dryness fraction of the steam after expansion. (0.86)

3.14 A quantity of steam enters a condenser operating at a pressure of 5kPa,

and is condensed to water. Calculate the heat removed per kilogram of steam. (2557kJ/kg)

374

Tutorial

3.3 Superheated vapour at 1MPa and 3000C is allowed to cool at constant

volume until the temperature drops to 1500C. At the final state, determine:

3.3.1 the pressure; (475.8kPa) 3.3.2 the quality; (0.656) 3.3.3 the enthalpy. (2019kJ/kg)


Is this a flow or non-flow process? What type of non-flow process is this? What information is supplied for initial and final state points? Can this information be used to determine the condition of the steam at any of the state points? By answering the above questions, you will be able to identify the process. You can now apply all the formulas pertaining to this process to find the answers.

This process can also be plotted on a pressure-volume and temperature- entropy diagram. Find answers to these questions and use them as a guide to solve this problem. You can add more questions if necessary. Apply the same approach to the remaining questions in the exercise.

375

Chapter 4

Throttling of steam

Example 1

Steam is supplied by a boiler plant to drive a turbine which in turn drives a generator that generates power for consumption. The absolute pressure in the main supply line was 1.5MPa. The pressure after throttling was 120kPa and the temperature 1100C. The mass of the water accumulated was 0.48kg and that of the condensate 4.58kg. For the quality of steam used, the specific heat capacity at constant pressure can be taken as 2.1kJ/kgK. A combined separating and throttling calorimeter was used during the test. Calculate the quality of steam in the main supply line. Questions to be asked in order for one to understand the problem and be able to answer the question: Q: what is meant by absolute pressure? A: on the pipe line will be a pressure gauge reading the pressure inside the pipe.

This reading on the pressure gauge added to the atmospheric pressure will give the absolute pressure in kPa. Atmospheric pressure can be given in kPa or mmHg. To convert mmHg to kPa simply divide the mmHg by 7.5. The pressure values used to take readings from tables and charts are the absolute values.

Q: how does a combined separating and throttling calorimeter works? A: to be able to understand the meanings of the readings taken during the test and

how to use it, it is important to understand the operation of a combined separating and throttling calorimeter. A combined separating and throttling calorimeter is a device that first separates the excess water from the steam by a sharp change in direction of flow. The heavier water droplets can not accomplish this and separates from the steam and is collected in the bottom of the device. The second process then allows the steam to flow through a throttling device which works very much the same as a needle valve. A certain amount of steam is allowed to slip through the opening created by the needle valve into a space at a lower pressure. This allows some of the water in the steam to vaporise further, changing the steam either into wet or superheated steam.

Q: how are the readings taken, used in calculating the quality of the steam? A: throttling is a flow process. Steam enters the device at a certain point with

specific properties and leave at another with different properties. The definition of throttling can be worded as follows:

376

Q 1 2

When there is flow in a rigid pipe (WD = 0), and there is a restriction to this flow, but the velocity before and after the restriction is the same (c1 = c2) and the heat flow during the flow is so small that it can be neglected (Q = 0), then we have a throttling process. From the steady flow energy equation: KE1 + PE1 + h1 + Q = KE2 + PE2 + h2 + WD

h1 = h2 for steam In the throttling calorimeter the enthalpy of the steam before and after throttling

remains unchanged, however the condition of the steam changes. During the throttling process the steam is more dried out, completely dried or superheated. Form the above steady flow energy equation it is clear that only one unknown can be present. During throttling the lowest value in terms of quality of the steam that can be used to solve the equation is dry steam. If the steam is throttled to the dry saturation line, its enthalpy value can be read of the steam tables or Mollier chart. The equation will be as follows:

h1 = h2 hf1 + x1hfg1 = hg2 all these values can be found and the unknown is the dryness fraction ’x1’ If the steam was throttled into the superheated region, the equation will look as

follows: h1 = h2

hf1 + x1hfg1 = hg2 + Cp(TF – TS) In this case the final pressure (P2) and temperature (TF) can be used to

determine the enthalpy value of the superheated steam from the Mollier chart. If Cp is given then the above formula must be used and hg2 and TS can be read of the steam table at the corresponding pressure. Again the only unknown will be the dryness fraction ‘x1’.

377

For the separating calorimeter the following relationship is used to determine the

dryness fraction of the wet steam passing through it: x0 = ms/(ms + mw) ms = mass of steam or condensate; mw = mass of water The product of x0 in the separating calorimeter and x1 in the throttling

calorimeter will give the dryness fraction in the supply line: x = x1 * x0 Now the question can be answered: x0 = ms/(ms + mw) = 4.58/(4.58 + 0.48) = 0.905 h1 = h2

hf1 + x1hfg1 = hg2 + Cp(TF – TS) 845 + x1*1945 = 2683 + 2.1*(110 – 104.8) x1 = 0.951 x = x1 * x0

x = 0.951*0.905 x = 0.86 → answer More relevant questions on this section

Q: How does a separating calorimeter works? A: A steam sample collected from the main supply enters the calorimeter. At the end of the collection tube a perforated dish ensures a change in flow direction. Here the heavier water droplets are separated from the lighter vapour droplets. This separated water is collected in a container. The dried out steam flows

378

further in the tube. It enters a condenser where it is completely condensed and collected in another container. (Read this while studying the sketch) Q: How is the steam quality determined when using a separating calorimeter? A: x0 = ms/(ms + mw) Q: How does a throttling calorimeter works? A: A steam sample collected from the main supply enters the calorimeter. At the throttling valve, small amounts of wet steam on the high pressure side, is allowed through to the low pressure side. This allows the steam to vaporize further. Depending on the pressure and temperature after throttling, the steam can be just dry or superheated. Q: How is the steam quality determined when using a throttling calorimeter? A: The definition of throttling states that enthalpy does not change during throttling. Therefore:

h1 = h2

hf1 + x1hfg1 = hg2 + Cp(TF – TS)

In these equations everything is known except the dryness fraction x1 which can be determined. Note that if the specific heat capacity of the superheated steam is not given, the value of the superheated enthalpy must be read off the Mollier chart or steam tables. In this case the equation on the right can not be used. Q: What is the least dryness fraction which can be theoretically determined under a given pressure? A: The steam must be dry saturated at least after throttling. This will give one equation with one unknown x1. If the steam is wet after throttling there will be two unknowns which make it imposseble to solve:

h1 = h2

hf1 + x1hfg1 = hf2 + x2hfg2 Both x1 and x2 are unknown and can not be solved. If the steam is dry saturated after throttling:

h1 = h2

379

hf1 + x1hfg1 = hg One unknown and x1 can be solved. Q: How is the pressure values given in a throttling calorimeter used during calculation? A: This depends upon the information given in the particular question. If the pressure values are absolute, then it can be read off the steam table directly. If the pressure values are gauge pressure, with atmospheric pressure available, then the absolute pressure value must be calculated: Pabs = PG + Patm = PG + mmHg/7.5 if atmospheric values are given in mmHg To find the absolute pressure value after throttling, when atmospheric pressure (barometer reading in mmHg) is given and the manometer reading in mmHg (gauge pressure after throttling) is available: Pabs = (Bh + Mh)/7.5

380

Exercise 4

4.1 The manometer reading of a throttling calorimeter is 70.5mmHg. The

barometer reading is 754.5mmHg and the gauge pressure in the main supply line is 940kPa. Determine the pressure of the calorimeter and the absolute pressure in the main supply line. (110kPa, 1040kPa)

4.2 A combined separating and throttling calorimeter is used to determine the

dryness fraction of steam in a main. The pressure of the steam in the main and the separator is 6.9bar. After throttling to 1.5bar the temperature is 1270C. During a ten-minute test 0.09kg of water is collected at the separator and 1.53kg of condensate is collected after throttling. Calculate the dryness fraction of the steam in the main. (0.927)

4.3 A combined separating and throttling calorimeter is used in test to determine

the dryness fraction of some steam. The following results were obtained during the test:

Pressure of the test steam = 1.2MPa Pressure of the steam after throttling = 150kPa Temperature of the steam after throttling = 1150C Mass of water collected in separator = 0.12kg Mass of condensate collected after throttling in the same time = 3.4kg From these results, determine the dryness fraction of the steam. (0.933) 4.4 A throttling calorimeter is used to determine the quality of steam which is at

a pressure of 2.2MPa. The pressure and the temperature after throttling are 0.12MPa and 109.60C, respectively. Determine:

4.4.1 the dryness fraction of the steam at 2.2MPa; (0.943) 4.4.2 the least dryness fraction which can be theoretically determined under the given pressure conditions. (0.938)

4.5 Wet steam was throttled in a throttle calorimeter and a manometer reading

of 97.5mmHg was obtained. If the barometer reading is 690mmHg, determine the pressure in the calorimeter. (105kPa)

4.6 Determine the degree of dryness of steam in a separator calorimeter which

has 0.2kg of water in the separator and 1.8kg of condensate. (0.9) 4.7 Steam at a gauge pressure of 640kPa was subjected to a throttle calorimeter

test and the following readings were obtained:

381

Barometer height = 750mmHg Manometer height = 75mmHg Thermometer reading 1150C Specific heat capacity Cp for superheated steam = 2.1kJ/kgK Calculate the dryness fraction of the steam. (0.972) 4.8 The mass of water accumulated in the separator of a combined separating

and throttling calorimeter during a dryness test is 2.24kg and the mass of the condensate 24kg. The pressure in the main supply line is 1300kPa and after throttling the pressure and temperature are 100kPa and 1050C. Calculate the degree of dryness in the main supply line. (0.87)

4.9 The following results were obtained during a dryness test using a separating

– throttling calorimeter:

Gauge pressure in the main supply line = 1.2kPa Mass of water accumulated = 0.46kg Mass of condensate = 5.54kg Barometer reading = 750mmHg Manometer reading = 150mmHg Temperature after throttling = 1200C Calculate the degree of dryness in the main supply line. (0.892)

Tutorial

4.1 The manometer reading of a throttling calorimeter is 70.5mmHg. The

barometer reading is 754.5mmHg and the gauge pressure in the main supply line is 940kPa. Determine the pressure of the calorimeter and the absolute pressure in the main supply line. (110kPa, 1040kPa)


What type of calorimeter is this? What information is supplied in the question? Are the pressure values supplied absolute or gauge values? Can the absolute values be determined? What must be determined and what are the formulas that can be used? By answering the above questions, you will be able to identify the process. You can now apply all the formulas pertaining to this process to find the answers.

The position of the steam after throttling can also be pinpointed on the Mollier

382

chart using the pressure and temperature values after throttling. The initial position can then be traced from this point to the left, where the horizontal line intersects the main pressure line. Find answers to these questions and use them as a guide to solve this problem. You can add more questions if necessary. Apply the same approach to the remaining questions in the exercise.

383

Chapter 5

Boiler and steam plant

Example 1

The following data refers to a test done on a water tube steam boiler: Mass of water evaporated = 4800kg/hr Mass of coal burnt = 9kg/min Calorific value of coal = 32 MJ/kg Air/fuel ratio = 12:1 Boiler pressure = 3MPa Supply water temperature = 47.70C Inlet temperature to evaporator = 850C Dryness fraction of steam leaving evaporator = 0.8 Superheated temperature of steam = 2500C Specific heat capacity of superheated steam = 2.15kJ/kgK Specific heat capacity of flue gas = 2.5kJ/kgK Calculate: 1.1 the efficiency of the boiler; 1.2 the equivalent evaporation from and at 1000C; 1.3 the amount of heat absorbed by the steam in the evaporator. Questions to be asked in order for one to understand the problem and be able to answer the question: Q: what is a steam boiler? A: it is a pressure vessel that converts water into steam. Q: how does this process take place inside the plant? A: water is supplied to the boiler plant which consists of a number of components.

There are water tube and flame tube boilers. In the water tube boilers the water flows inside the tube and in the flame tube boilers the hot flue gas from the fire flows inside the tubes. At the end of the day the purpose is to convert water into steam with the available heat. The plant may have an economizer, the plant will have a boiler (evaporator) and it may have a super heater. These components are necessary to convert the supply water into steam. The plant may have an air cooler to preheat the air before it enters the combustion chamber to improve the combustion efficiency. As the water flow through these components the temperature is increased up to the desired temperature at outlet. The process through a boiler plant is a constant pressure process and once the outlet

384

temperature is increased above the boiler pressure is the steam superheated. The heat required to increase the water temperature is receive from the heat of the combustion chamber. Different types of boilers are available for e.g. coal fire boilers, electrode boilers, diesel/crude oil boilers. Once the steam has reached its desired temperature, it leaves the boiler plant to be applied at the consumption point.

1.1 Q: what is the efficiency of a boiler plant? A: it is the ratio of the heat absorbed by the water as it flows through the plant, to

the heat generated by the combustion chamber. The heat generated by the combustion chamber depends upon the calorific value of the fuel used by the plant, in the case of a coal or diesel fuel/crude oil boiler, or the wattage (or current) generated by the electrodes of the electrode boiler. The ratio is express in the following equation:

η = [ms(h1 – h0)]/[mf*CV)] where, ms = mass flow rate of steam generated in kg/s or kg/min or kg/hr or kg

steam generated per kg fuel burnt h1 = the enthalpy of the steam leaving the plant at boiler pressure and final

temperature h0 = the enthalpy of the water entering the plant mf = the mass flow rate of the fuel supplied to the combustion chamber in

kg/s or kg/min or kg/hr or kg /kg steam generated CV = the calorific value of the fuel used in the combustion chamber. This is

the heat released per kg of fuel burnt. To answer the first question: η = [ms(h1 – h0)]/[mf*CV)] h1 = 2858 kJ/kg from table or chart h0 = 4.187*47.7 = 199.72 kJ/kg from tables η = [4800(2858 – 199.72)]/[9*60*32000] = 73.84% → answer

385

Note: the mass of fuel and steam must be in the same units when substituted

into the equation. Q: what will influence the efficiency of the boiler plant? A: there are a number of factors that can influence the efficiency of the boiler plant.

A few are listed for this example: The quality of coal, if the calorific value of the coal supplied is different than the correct value, the heat given of during combustion will be different and that will affect the quality of steam produced. Dirty components (economizer, evaporator, super heater), if these components have dirty tubes (inside or outside or both sides of the tubes) then the heat transfer process will be delayed and the necessary heat will not be given to the water/steam circulating through the components. This can be reduce to a large extent by feed water treatment with different chemicals (read about the chemicals used and their purpose) to purify the water. This purification process will reduce scale built-up on tube walls and reduce corrosion of boiler components which will prolong the plants’ lifespan. Worn feed pump, this will not supply the correct amount of water to the plant which can cause overheating and bursting of tubes. Dirty air pre-heater, this will affect the combustion efficiency and the heat given of to the steam.

1.2 Q: what is the equivalent evaporation of a boiler plant? A: it is the amount of water at 1000C that this plant can convert to steam at 1000C

by the heat of 1kg of fuel burnt. Remember that the heat required to change water into steam is called latent heat and that during this process the temperature of the water remains constant, it is merely a phase change. The expression for equivalent evaporation is as follows:

EE = [ms(h1 – h0)]/[mf*2257)]

hfg = 2257kJ/kg is the latent heat of evaporation required to change 1kg of water at 1000C into steam at 1000C.

EE = [4800(2858 – 199.72)]/[9*60*2257] EE = 10.47kg steam/kg fuel → answer 1.3 Q: the amount of heat absorbed by the steam in the evaporator? A: to be able to answer this question it is important to know what the general

386

process in a boiler plant is. Heat transfer takes place in each of the components that the plant consists of until the steam leaves the plant at the correct temperature. In each of the components a different amount of heat is absorbed by the water/steam. This is determined by the design of the component. To calculate this heat absorption, it is important to know what happens in the component under discussion. In this case the water enters the evaporator at temperature near boiling point. During its passage through the evaporator, the water absorbs heat from the flue gas and is converted into steam (wet). The amount of heat absorbed during the process can be determined by the inlet and outlet temperature of the water/steam or the temperature drop of the flue gas across the evaporator. The equation for this is:

Qevap = mflue*Cpflue*(Tb – Te) = ms*Cpsteam*(Ts – T1) where Qevap = heat supplied absorbed in the evaporator mflue = mass flow rate of the flue gas Cpflue = specific heat capacity of the flue gas Tb = temperature of flue gas at entry to the evaporator Te = temperature of flue gas at exit from the evaporator ms = mass flow rate of the steam Cpsteam = specific heat capacity of the steam Ts = temperature of the steam leaving the evaporator T1 = temperature of the steam leaving the evaporator Qevap = 4800/3600*2.15*(233.8 – 85) = 426.56kJ/s → answer More relevant questions on this section

Q: How is the heat transfer in each component calculated? A: Economiser: Qecon = mflue*Cpflue*(Te – Tex) = ms(h01 – h0)

387

Evaporator: Qevap = mflue*Cpflue*(Tb – Te) = ms(hwet – h01) Super heater: Qsuph = mflue*Cpflue*(Tc – Tb) = ms(h1 – hwet) Air pre-heater: Qair = mflue*Cpflue*(Tex1 – Tex) = maCpa(Ta2 – Ta1) Q: How is the performance of these components expressed as a percentage of total heat absorbed, as a percentage of total heat available and per kilogram of fuel burned? A: Expressed as a percentage of total heat absorbed: Qtot abs = ms(h1 – h0) % absorbed in economiser:

%Qecon = Qecon/Qtot abs * 100 % absorbed in evaporator:

%Qevap = Qevap/Qtot abs * 100 % absorbed in super heater:

%Qsuph = Qsuph/Qtot abs * 100 Expressed as a percentage of total heat available: Qin = mf * CV

% absorbed in economiser:

%Qecon = Qecon/Qin * 100 % absorbed in evaporator:

%Qevap = Qevap/Qin * 100

388

% absorbed in super heater:

%Qsuph = Qsuph/Qin * 100 Expressed per kilogram fuel burnt: In economiser: Qecon = ms(h01 – h0)/mf

In evaporator: Qevap = ms(hwet – h01)/mf

In super heater: Qsuph = ms(h1 – hwet)/mf

In air pre-heater: Qair = maCpa(Ta2 – Ta1)/mf

Q: What other types of boiler/steam generating plant are there? A: Water tube boilers: Electric boilers, gas/oil boilers, coal boilers Fire tube boilers: Coal boilers (fossil fuel)

Q: Which different types of fuel or methods of converting water into steam can be used?

A: Electricity (electrode boilers), coal, gas/oil, nuclear power (Boiling water reactors – BWR and Pressurized water reactors - PWR)

Nuclear boilers are becoming a more attractive alternative – find out how do these units convert water into steam, what is the fuel used and what are the health and safety risks posed by these plants. How are these problems overcome? Q: How do these plants generate steam from water? A: Water tube boilers: In the combustion chamber heat is generated by burning the fuel and forming

389

flue gas (hot combustion gas). Water flows inside the tubes and is heated up by the flue gas from the combustion chamber which heats up the tube walls on the outside, until it is converted into steam. This process can take place in different section of the tubes called the economiser, evaporator and super heater. These boilers can operate at high pressures and can supply large amounts of steam over 1000 000kg/hr. Fire tube boilers: In the combustion chamber heat is generated by burning the fuel and forming flue gas (hot combustion gas). Water flows on the outside of the tubes and is heated up by the flue gas from the combustion chamber which heats up the tubes from the inside as it flows through it. These boilers are not suitable for high pressure and are much smaller in capacity e.g. a size of 500kg/hr. Q: Which chemicals are used to purify water? A: Advantage is a corrosion and deposit inhibitor.

Drewplex AT to control scale and deposits, and Drewplex OX corrosion inhibitor.

GC (concentrated alkaline liquid) to prevent calcium scale deposits, by converting calcium hardness into soft, non-adherent sludge that is easily removed by blow down.

Q: Which safety devices are required on these plants to make them legal? A: Two water level indicators Two water supply pumps High pressure safety valves Thermometers Blow down valves Q: which additional chemical is used in electric boilers and for what reason? A: THIS ANSWER IS LEFT TO THE READER TO INVESTIGATE AS PART OF

PROJECT 1. Q: What is the environmental impact of the exhaust gases produced by these plants? A: THIS ANSWER IS LEFT TO THE LEANER TO INVESTIGATE AS PART OF

PROJECT 1.

390

Q: How can this negative impact be reduced? A: By reducing the amount of flue gas released to atmosphere and by improving the efficiency of the plant so that more heat absorption takes place and the flue gas exit temperature is lower. Q: What are the start-up procedures and shut-down procedures for such a plant? A: THIS ANSWER IS LEFT TO THE LEANER TO INVESTIGATE AS PART OF

PROJECT 1. Q: What maintenance is done to ensure effective operation and prolonged lifetime? A: Treatment of supply water to the plant. Safety devices to ensure operation stay within the design specifications. Scheduled maintenance to ensure all components are in good working

order. Testing the quality of fuel supplied.

391

Exercise 5.1

5.1.1 A boiler with super heater generates 6000kg/hr of steam at a pressure of

1.5MPa, 0.98 dry at exit from the boiler and at a temperature of 3000C on leaving the super heater. If the feed water temperature is 800C and the overall efficiency of the combined boiler and super heater is 85%, determine:

5.1.1.1 the amount of coal of calorific value 30MJ/kg used per hour; (636kg/hr) 5.1.1.2 the equivalent evaporation from and at 1000C for the combined unit; (11.3kg/hr) 5.1.1.3 the heating surface required in the super heater if the rate of heat transmission may be taken as 450 000kJ/m2 of heating surface per hour. (3.85m2)

5.1.2 A boiler is to produce 6250kg/hr of steam superheated by 400C at a

pressure of 2.1MPa. The temperature of the feed water is 500C. If the thermal efficiency of the boiler is 70%, how much fuel oil will be consumed in one hour? The calorific value of the fuel oil used is 45MJ/kg, Cp for superheated steam = 2.093kJ/kgK (531kg)

5.1.3 The feed water to a boiler enters an economizer at 320C and leaves at

1200C, being fed into the boiler at this temperature. The steam leaves the boiler 0.95 dry at 2.0MPa and passes through a super-heater where its temperature is raised to 2500C without change in pressure. The steam output is 8.2kg/kg of coal burned and the calorific value of the coal is 28MJ/kg. Take the specific heat capacity of superheated steam = 2.093kJ/kgK and that for the feed water = 4.18kJ/kgK. Determine the energy received per kilogram of water and steam in the following components and express your answers as percentages of the energy supplied by the coal:

5.1.3.1 the economizer; (10.77%) 5.1.3.2 the boiler; (64.5%) 5.1.3.3 the super-heater. (5.07%)

5.1.4 In a test on a boiler, the following observations were made:

Coal burned per hour = 480kg Water evaporated per hour = 4375kg

Boiler pressure = 3.0MPa Feed water temperature = 950C Temperature of steam leaving the boiler = 2600C Calorific value of coal used = 30.7MJ/kg

392

Take: Cp of superheated steam = 2.093kJ/kgK Determine:

5.1.4.1 the efficiency of the boiler; (73%) 5.1.4.2 the equivalent evaporation from and at 1000C. (4769kg/hr)

5.1.5 The equivalent evaporation of a boiler from and at 1000C is 10.4kg

steam/kg fuel. The calorific value of the fuel is 29800kJ/kg. Determine the efficiency of the boiler. (78.8%)

If the boiler produces 15000kg steam/hr at 24bar from feed water at 400C, and the fuel consumption is 1650kg/hr, determine the condition of the steam produced. (0.972)

5.1.6 A boiler produces steam at a pressure of 3.0MPa and with a temperature of

3000C from feed water at 600C. The steam is supplied to a turbine developing 2.5MW with a steam consumption of 15120kg/MWhr (i.e.4.2kg/MJ). The coal burned in the boiler has a calorific value of 31.6MJ/kg and the boiler efficiency is 82%. Determine the required grate area of the furnace for a firing rate of 215kg/m2 of grate area/hour. (18.6m2)

5.1.7 A boiler uses supply water at 37.70C. Steam leaves the boiler 0.93 dry at a

pressure of 2MPa and passes through a super-heater at constant pressure where its temperature is raised to 3100C. The steam output is 9.5kg/kg coal burnt with a calorific value of 37.5MJ/kg. Calculate:

5.1.7.1 the boiler efficiency; (73.26%) 5.1.7.2 the equivalent evaporation from and at 1000C; (12.2kg/kgf) 5.1.7.3 the heat transfer per kilogram fuel in the evaporator; (23638kJ/kg) 5.1.7.4 the heat transfer per kilogram fuel in the super-heater. (3660kJ/kg)

Tutorial

5.1.1 A boiler with super heater generates 6000kg/hr of steam at a pressure of

1.5MPa, 0.98 dry at exit from the boiler and at a temperature of 3000C on leaving the super heater. If the feed water temperature is 800C and the overall efficiency of the combined boiler and super heater is 85%, determine:

5.1.1.1 the amount of coal of calorific value 30MJ/kg used per hour; (636kg/hr)

393

5.1.1.2 the equivalent evaporation from and at 1000C for the combined unit; (11.3kg/hr) 5.1.1.3 the heating surface required in the super heater if the rate of heat transmission may be taken as 450 000kJ/m2 of heating surface per hour. (3.85m2)

Questions relevant to understand and solve this problem: Which components are involved in this plant? How can the given information be used? Where does the information feature on the diagram? What must be determined and which formulas can be used? By answering the above questions, you will be able to identify the process. You can now apply all the formulas pertaining to this process to find the answers. Find answers to these questions and use them as a guide to solve this problem. You can add more questions if necessary. Apply the same approach to the remaining questions in the exercise.

394

Rankine Cycle

Example 2

A steam plant operates on a Rankine cycle between a pressure of 75kPa and 4000kPa. The steam enters the turbine at a temperature of 4500C and expansion through the turbine takes place isentropically. Determine:

2.1 the work done by the turbine; 2.2 the Rankine efficiency, neglecting pump work; 2.3 the specific steam consumption; 2.4 the work ratio.

Questions to be asked in order for one to understand the problem and be able to answer the question: Q: what is a Rankine cycle? A: first the name Rankine was the surname of the person who developed this cycle,

William John Rankine from Glasgow University Professor. This cycle consists of a number of components with each a specific function. The components are: condenser, feed pump, boiler plant, turbine and cooling tower with all its accessories. The condenser condenses the wet steam coming from the turbine (read about the different type of condensers and how they operate). The feed pump pumps the condensate back to the boiler (read about the different types of feed pumps and how they function). The boiler converts the condensate to steam at the required superheated temperature at boiler pressure (read about the different type of boilers and how the operate. This will be revision because the section on boilers has just been completed). The turbine is driven by the steam and drives a power generator which generates power (read about the different types of turbine and how they function). The cooling tower cools the hot water which circulates through the condenser tubes and in the process absorbs heat from rejected by the steam, to enable the steam to condense (read about different types of cooling towers and how they function). The circulating fluid through the Rankine cycle is obviously water converted to steam.

Q: what are the two pressure values given in the question? A: the lower pressure (P2) the condenser pressure and the higher pressure (P1) the

boiler pressure. The boiler pressure will be the design pressure for a particular boiler and is the safe operating pressure for that plant. Remember the higher the water pressure, the higher the boiling point and the higher the enthalpy (energy) value of the steam produced. This steam must drive a specific turbine which requires a certain amount of energy to operate it at optimum capacity. The condenser pressure is lower than atmospheric pressure and this allows the turbine to generate more power. The higher the pressure drops across the

395

turbine the higher the energy given of to the turbine. By dropping the condenser pressure to a value below atmospheric pressure allows for this.

Q: what is the meaning of the temperature value at entry to the turbine? A: this value together with the pressure value enables one to determine the

enthalpy of the steam at entry to the turbine. Q: what is isentropic expansion through the turbine? A: the process through the turbine is a flow process. The steam enters with specific

properties and leaves with specific properties. During this expansion there is no heat flow to or away from the turbine. This means that the process can be plotted on a Mollier chart and temperature-entropy diagram by a vertical line (no area under the graph, no heat flow).

2.1 Q: how is the turbine work done calculated? A: steam enters the turbine with a certain enthalpy and leaves with a different

enthalpy. The difference between these values is the work done per kilogram of steam flow through the turbine. There is no mass flow indicated in the question and hence the work done will be expressed per kilogram.

Q: how is the outlet enthalpy determined? A: on the Mollier chart the entry point is marked by using the 4000kPa and 4500C

values. A vertical line is drawn from this point until it intersects with the 75kPa condenser pressure line. This point is marked and the enthalpy is read off. At this point the dryness fraction line running through the point indicated the condition of the steam at outlet from the turbine.

WDT = h1 – h2

= 3330 – 2470 = 860kJ/kg → answer 2.2 Q: what is the Rankine efficiency? A: it is a ratio between the useful work done by the turbine and the amount of heat

supplied to convert the water to steam in the boiler plant. It can be expressed as follows:

ηR = [(h1 – h2) –( h4 – h3)]/[( h1 – h3) –( h4 – h3)] where

396

h1 – h2 positive work done through turbine h4 – h3 negative work done by feed pump h1 – h3 heat supplied to water in boiler plant h4 – h3 heat supplied to water by feed pump Q: how is the value of h3 and h4 determined? A: the process inside the condenser is complete condensation. The wet steam

enters the condenser and latent heat is removed until the steam is condensed to saturated water. The temperature during this process is constant (latent heat) and the pressure inside the condenser is constant. The exit point from the condenser is the point where the condenser pressure line intersects with the saturated liquid line and the enthalpy at this point is hf, read of the tables. The work done through the feed pump can be expressed by the following equations:

WDf/p = h4 – h3 = (m/ρ)/(P1 – P2) = Vs/(P1 – P2) m = mass of water (kg) Vs = specific volume of water (m3/kg) ρ = density of water (kg/m3) Q: what does the statement ‘neglect pump work’ means? A: this means that the difference between the inlet and outlet enthalpy value of the

water though the feed pump is so small and ha so little influence on the calculations that the value of h3 and h4 for calculation purposes can be taken as being equal. This will simplify the Rankine efficiency formula to the following:

ηR = (h1 – h2)/( h1 – h3) = (3330 – 2470)/(3330 – 385) = 29.2% → answer 2.3 Q: what is the specific steam consumption of a plant? A: it is the amount of steam at the boiler pressure and outlet temperature required

to generate 1kW and it is indicated by the symbol Ssc. The unit for specific steam consumption is kg/kWhr (read about this particular unit and why it is expressed in this form). Specific steam consumption can be expressed as follows:

Ssc = 3600/(h1 – h2) = 3600/(3330 -2470)

397

= 4.186kg/kWhr → answer 2.4 Q: what is the work ratio of a plant? A: the ratio (rw) of the net work output to the gross work output is called the work

ratio. This ratio gives an indication of the plant size. The following equation can be used to express this relationship:

rw = (net work done)/(positive work done) = [(h1 – h2) –( h4 – h3)]/ (h1 – h2) = [(3330 - 2470) – (1/1000(4000 – 75)]/(3330 – 2470) = 0.995 → answer P1

T 1 1 – 2 turbine work done 2 – 3 heat removed in

condenser 4 P2 3– 4 feed pump work

done

4 – 1 heat supplied by 3 2 boiler

s1 = s2 s

398

1 Turbine Sup/h Evap 2 Econ Cond 4 3 Feedpump

More relevant questions on this section Q: How does the quality of the steam at entry to the turbine impact on the plant performance? A: The higher the enthalpy of the steam the more energy is available for driving the turbine. Therefore super heated steam will drive a larger unit more effectively than saturated or even wet steam. Q: How can the quality of steam at exit from a multi-stage turbine impact on the life span and performance of the unit? A: If the steam is to wet at exit from the turbine it can cause corrosion in the unit which will result in a reduction in the lifespan. If the steam starts to condense inside the unit it will result in power lost due to the fact that the heavier water molecules have different flow characteristics to that of the lighter vapour molecules. Q: What can be done to overcome this? A: In large units (many stages) the steam is tapped off at a specific point and return to the boiler plant to be re-heated again. This will ensure that steam leaves the unit with the correct dryness fraction. Q: If expansion through the turbine is not isentropic, how will this impact on the power developed by this unit? A: Isentropic expansion through the unit means that no heat flows and that the process takes place on a constant entropy line. Point 2 will also be the lowest point achieved, which makes the enthalpy difference between point 1 and 2 a

399

maximum. If the expansion is not isentropic, it means that heat flow exits and that it is because of friction between the steam molecules internally and between the steam molecules and the metal surfaces. This means that the enthalpy value of the steam at exit (numbered as 2’) is closer to point 1 then that of the isentropic value and therefore the energy available for driving the turbine is less. On the temperature-entropy diagram line 1-2’ is slightly curved to the right and not vertical like line 1-2. The area under this line indicates the heat flow because of friction. Q: What can cause the expansion through the turbine not to be isentropic? A: Lubrication, internal friction between molecules and between molecules and the metal surface finishes and difference in density between water and vapour molecules. Q: How can this new power be calculated?

A: I = (h1 – h2’)/(h1 – h2) = isentropic efficiency Enthalpy h1 and h2 can be read off the Mollier chart and substituted into this equation to determine h2’. The actual turbine work done is the calculated as follow:

WDT = h1 – h2’

Q: Why can the steam from the turbine not be exhaust into the atmosphere?

A: Condensers operates at pressures lower than atmospheric pressure to allow for a greater enthalpy change across the turbine. The exhaust from the turbine must therefore be directly into the condenser to maintain this condition. The steam used in these plants is treated water and is therefore kept in a close system to minimize treatment costs. The temperature at exit from the condenser is also much higher than the make-up water temperature which further reduces the amount of heat required to achieve the desired exit conditions. Q: What will the influence be on the plant performance if the condenser is under-cooling the condensate too much? A: Under-cooling in a condenser means that the water leaves the condenser at a lower temperature then the saturation temperature corresponding with pressure 2. This will result in ‘cooler’ water entering the boiler plant, which means more energy will be required to achieve the required exit conditions from the plant. This in turn means more heat required, i.e. more fuel burn which results in

400

higher running costs.

401

Exercise 5.2

5.2.1 Steam is supplied dry saturated at 40bar to a turbine and the condenser pressure is 0.035bar. If the plant operates on the Rankine cycle, calculate per kilogram of steam:

5.2.1.1 the work output neglecting the feed pump work; (982.4kJ) 5.2.1.2 the work required for the feed pump; (4kJ) 5.2.1.3 the heat transfer to the condenser cooling water, and the amount of cooling water required through the condenser if the temperature rise of the water is assumed to be 5.5K; (1706.6kJ, 74.1kJ) 5.2.1.4 the heat supplied; (2685kJ) 5.2.1.5 the Rankine efficiency; (36.6%) 5.2.1.6 the specific steam consumption. (3.66kg/kWhr)

5.2.2 A steam turbine is supplied with steam at a pressure of 2.5MPa and a

temperature of 3000C and exhausts into a condenser where the pressure is 20kPa. The steam consumption is 6000kg/hr and the thermal efficiency is 20%. Determine the power developed by the turbine. (920kW)

If the dryness fraction of the exhaust steam is 0.95, the temperature of the condensate is 600C and the mass of the cooling water is 90 000kg/hr, determine the rise in temperature of the cooling water in passing through the condenser. (35.70C)

5.2.3 Steam at a pressure of 4MPa and a temperature of 3500C expands to

100kPa in a steam turbine. Calculate the Rankine efficiency and steam consumption per kWhr. (26%, 5.1kg)

5.2.4 A steam plant operating on the Rankine cycle has a supply to the turbine,

superheated with a temperature of 2500Cand a pressure of 900kPa. After expansion in the turbine the steam has a dryness fraction of 0.9. Determine:

5.2.4.1 the condenser pressure; (45kPa) 5.2.4.2 the steam enthalpies at the main points; (2948kJ/kg, 2415kJ/kg, 330kJ/kg, 331kJ/kg) 5.2.4.3 the thermal efficiency of the plant; (20.36%) 5.2.4.4 the efficiency ratio with a rate of steam used at 7.5kg/kWhr and the condensate temperature 700C. (0.88)

5.2.5 Consider a 300MW steam power plant which operates on a simple ideal

Rankine cycle. Steam enters the turbine at 10MPa and 5000C and is cooled in the condenser at a pressure of 10kPa. Determine:

402

5.2.5.1 the quality of steam at the turbine exit; (0.793) 5.2.5.2 the mass flow rate of the steam.(235.4kg/s)

Tutorial

5.2.1 Steam is supplied dry saturated at 40bar to a turbine and the condenser

pressure is 0.035bar. If the plant operates on the Rankine cycle, calculate per kilogram of steam:

5.2.1.1 the work output neglecting the feed pump work; (982.4kJ) 5.2.1.2 the work required for the feed pump; (4kJ) 5.2.1.3 the heat transfer to the condenser cooling water, and the amount of cooling water required through the condenser if the temperature rise of the water is assumed to be 5.5K; (1706.6kJ, 74.1kJ) 5.2.1.4 the heat supplied; (2685kJ) 5.2.1.5 the Rankine efficiency; (36.6%) 5.2.1.6 the specific steam consumption. (3.66kg/kWhr)

Questions relevant to understand and solve this problem: What is the inlet condition of the steam to the turbine? Is the expansion through the turbine isentropic? How can the given information be used? What must be determined and what are the formulas that can be used? By answering the above questions, you will be able to identify the process. You can now apply all the formulas pertaining to this process to find the answers. Find answers to these questions and use them as a guide to solve this problem. You can add more questions if necessary. Apply the same approach to the remaining questions in the exercise.

403

Chapter 6

Condensers

Example 1

A steam turbine discharges 5000kg of steam per hour at 400C and with a dryness of 0.85. The estimated air leakage is 15 kg/hr. The temperature at the suction of the air pump is 320C and the temperature of the condensate is 350C. The barometer reading is 760mm Hg. Calculate:

1.1 the vacuum gauge reading;

1.2 the loss of condensate in kilogram per hour;

1.3 the quantity of cooling water required if the rise temperature of the cooling

water is limited to 100C. Questions to be asked in order for one to understand the problem and be able to answer the question: Q: what do I do with the values given in the question? A: the turbine in the question forms part of the Rankine cycle and therefore the

discharged steam will enter the condenser where it will be condensed. The information in this question is that for the condenser in the cycle and will be used to answer the questions asked.

Q: what is a condenser and how does it function? A: condensers can be divided into two main groups: surface condensers and jet

condensers. A surface condenser consists of a shell with a large number of tubes inside. The steam will enter the condenser at the top and leave at the bottom as condensate (hot water). Cooling water will flow through the tubes and will completely condense the steam. The steam and cooling water does not mix and this makes this type of condenser very popular (read about jet condensers, their construction, how they operate and their application). The steam is treated feed water to the boiler and is more pure than the circulating cooling water. Mixing the two will require more water treatment, pushing up running costs. During the flow of steam and cooling water, heat is rejected by the steam and absorbed by the cooling water. The cooling water will therefore enter with a specific temperature and leave with a specific higher temperature. This is referred to as the temperature rise of the cooling water. It is also clear to see that there is a direct relationship between the amount of cooling water and the amount of

steam circulating through a specific condenser. This relationship can be expressed as follows:

404

Heat rejected by steam = heat absorbed by cooling water ms*[x*hfg + 4.187*(Ts – Tk)] = mw*4.187*(tw2 – tw1) where ms = mass of steam entering the condenser or the mass of condensate leaving x = the quality of the steam entering hfg = latent heat of evaporation of steam at condenser pressure Ts = saturation temperature of steam corresponding to condenser pressure Tk = condensate temperature at exit from the condenser mw = mass flow rate of the cooling water tw1 = cooling water temperature at entry

tw2 = cooling water temperature at exit The condenser also operates at a pressure lower than atmospheric pressure

which means it is pressurized by the air surrounding it. This results in air leaking into the system, which must be removed to prevent it from lowering the boiler efficiency. The device used to remove the air is called an air pump. (Read more about the different types of air pumps and their operation). The air leakage value in this question indicates the air leaking into the condenser.

2.1 Q: what is the vacuum gauge reading? A: the condenser operates at a pressure lower than atmospheric pressure. Any

pressure lower than atmospheric pressure, is referred to as a vacuum. The vacuum gauge reading is therefore the condenser gauge pressure reading, normally expressed in millimeters mercury (mmHg). There is also a relationship between the condenser pressure, atmospheric pressure and vacuum gauge reading and can be expressed in the following relationship:

Pc = (Bh – Vm)/7.5 where Pc – condenser pressure in kPa Bh – atmospheric pressure at the specific location in mm Hg Vm – vacuum gauge reading on the condenser in mm Hg Q: how is condenser pressure determined? A: the steam in this question enters the condenser as wet steam and will therefore

be at the saturation temperature corresponding with the condenser pressure. The temperature is 400C and the condenser pressure can be read of the steam table from this value as 7.384kPa.

To answer the question:

405

Pc = (Bh – Vm)/7.5

7.384 = (760 – Vm)/7.5 Vm = 704.95mm Hg → answer 2.2 Q: what is the loss of condensate kilogram per hour? A: it is the amount of treated boiler feed water (condensed steam) which is pumped

away by the air pump drawing the air from the system. Q: how is this condensate loss value calculated? A: the loss of condensate is the amount of feed water extracted with the air by the

air pump. To determine the amount of condensate loss it is important to know what the air pump suction spout temperature is. If this temperature is the same as that of the condensate it is called a wet air pump. If the suction spout temperature is different to that of the condensate then it will be given in the question and this air pump is called a dry pump. This is the case in the given question. The mass of condensate is calculated from the following relationship:

mv = Va/Vg where mv = mass of condensate in kg/hr Va = volume of the air at air pump suction in m3/hr at the partial pressure of

the air at this point Vg = volume of the dry saturated vapour at air pump suction in m3/kg at the

partial pressure of the vapour at this point Q: what is the partial pressure of the air and the vapour at a specific point? A: according to Dalton-Gibbs law of partial pressures the total pressure of a space is

made up by the sum of the partial pressures of the individual gases in the space at the same temperature. Look at the following example. A container is filled with two gases, A and B. The total pressure (PT) in the cylinder will then be PT = PA + PB, where PA and PB are the partial pressures of gases A and B individually where both these gases are at the same temperature.

Pc = Pv + Pa where Pc = condenser pressure

406

Pv = partial pressure of the vapour at the suction spout temperature Pa = partial pressure of the air Q: how are Pa and Pv determined? A: Pv is found from the steam tables at the air pump suction temperature. Pa is then

determined from the above equation. The following steps can be followed: Pc = Pv + Pa 7.384 = 4.799 + Pa Pa = 2.59kPa PaVa = maRaTa

2.59 * Va = 15 * 0.287 * (32 + 273) Va = 507.9 m3/hr Vg is read off from the steam tables at 320C as 29.82m3/kg. mv = 507.9/29.82 = 17.031kg/hr → answer 2.3 Q: what is the amount of cooling water required if the temperature rise of the

cooling water is kept to 100C? A: from the explanation of the condenser operation the following relationship is

made between the heat rejected by the steam and the heat absorbed by the cooling water:

ms*[x*hfg + 4.187*(Ts – Tk)] = mw*4.187*(tw2 – tw1) 5000*[0.85*2406.72 + 4.187*(40 – 32)] = mw * 4.187 * (10) mw = 248293.29kg/hr → answer

More relevant questions on this section Q: Which different types of condensers are there?

407

A: The main categories for condensers are: surface condensers and jet condensers. Types of surface condensers: Single pass, two pass condensers Regenerative condensers Evaporative condensers Types of let condensers: Low level jet condensers (parallel flow or counter flow) High level jet condensers THE INVESTIGATION OF THE FOLLOWING IS LEFT TO THE READER: THE TYPES OF SURFACE AND JET CONDENSERS AND THEIR OPERATION; THE ADVANTAGES AND DISADVANTAGES OF EACH CATEGORY; THE INDUSTRIAL APPLICATION OF EACH CATEGORY Q: How does the inside configuration of these categories differs from one another? A: Surface condensers: In these units the hot and cold water circuits are not mixing which allows for the re-use of treated condensate from the turbine. The one fluid will enter the shell and flow over the tubes and the other will enter the tubes and flow through them. This reduces the water treatment of the boiler plant. Jet condensers: The hot and cold fluid enters a common chamber and mixes. The mixture is then re-circulated to the plant for use. Q: Heat flows from the hot fluid to the tube and from the tube to the cold fluid, what are the formulas to determine this relationship of heat transfer?

A: Heat rejected by steam = heat flow through tube walls = heat absorbed by cooling water

ms*[x*hfg + 4.187*(Ts – Tk)] = AUTln = mw*4.187*(tw2 – tw1)

408

Q: What is the overall heat transfer coefficient ‘U’ for a unit? A: It is a heat transfer coefficient which includes the convection heat transfer coefficient between the hot fluid and the tube walls, the thermal conductivity of the tube walls for conduction heat transfer through the tube walls and the convection heat transfer between the tube walls and the cold fluid. The formula also caters for the effect of scale built-up on the tube inside and outside walls which act as an insulator which reduces the heat transfer rate. The calculation of the overall heat transfer coefficient will be done at a later stage and does not form part of this syllabus. Q: What is the logarithmic mean temperature difference? A: This is a formula used to trace the average temperature difference between the hot and cold fluid as they flow through the condenser. Q: How is the logarithmic mean temperature difference determined for a specific unit? A: Tln = [T1 - T2]/[ln(T1/T2)]

Parallel flow: Counter flow: Tcold in

Thot in Thot in Tcold in

409

Thot in Thot in

T1 Tcold out Thot out

T1 Tcold out T2 Thot out

T2

Tcold in

T cold in

Q: How does the internal configuration impact on this calculation? A: If there are more than one tube pass a correction factor must be brought in because the above calculation is for pure parallel or pure counter flow units. This will be done at a later stage and is not included in this syllabus. Q: How is the condenser efficiency determined? A: c = (tw2 – tw1)/(Ts – tw1) Q: Why will a wet air pump be replaced with a dry air pump? A: The dry air pump suction temperature is lower than that of the wet air pump which means that less vapour will be pumped out. This means a reduction in make-up water as well as water treatment costs. The size of the dry air pump is also smaller than that of the wet air pump, which also means a saving in electricity due to the smaller electrical drive motor.

410

Exercise 6

6.1 A surface condenser is fitted with separate air and condensate outlets. A portion of the cooling surface is screened from the incoming steam and the air is passes over these screened tubes to the air extraction and becomes cooled below the condensate temperature. The condenser receives 20 000kg/hr of dry saturated steam at 36.20C. At the condensate outlet the temperature is 34.60C and at the air extraction the temperature is 290C. The volume of air and vapour leaving the condenser is 3.8m3/min. Assume constant pressure throughout the condenser, calculate:

6.1.1 the mass of air removed per 10 000kg of steam; (2.63kg) 6.1.2 the mass of steam condensed in the air cooler per minute; (0.5kg/min) 6.1.3 the heat rejected to the cooling water. (13451kW)

6.2 A condenser condenses 2700kg steam per hour while air leaks into it at

2.2kg/hr. The condensate and air suction spout temperatures are 32.90C. The barometer and vacuum gauge readings are 765mmHg and 690mmHg respectively. The condenser uses 125.55Mg of cooling water per hour to condense steam with a dryness fraction of 0.86 and the air pump has a volumetric efficiency of 82.5%. Take R = 0.287kJ/kgK for air and calculate:

6.2.1 the temperature rise of the cooling water; (10.850C) 6.2.2 the air pump capacity in m3/min. (0.78m3/min)

6.3 5595kg of steam with a dryness fraction of 0.85 is condensed per hour by a

surface condenser while air leaks into it at a rate of 0.87kg/1000kg of steam condensed. The barometer reading is 745.5mmHg and the vacuum gauge reading 674.25mmHg. The temperature of the air suction spout of the air pump and condensate are each 37.70C and R for air is 0.287kJ/kgK. The cooling water enters and leaves the condenser at 17.50C and 40.50C respectively. Calculate:

6.3.1 the cooling water required in m3/min; (2m3/min) 6.3.2 the capacity of the air pump in m3/min if an air cooler which cools the air to 21.10C before it is pumped out, is fitted; (0.978m3/min) 6.3.3 the percentage saving in pump volume by cooling the air from 37.70C to 21.10C. (59.4%)

6.4 A condenser works under a vacuum of 700mmHg while air leaks into it at a

4.25kg/hr. The air pump extraction spout has a temperature of 32.90C and the barometer reading is 760mmHg. Take r for air 0.287kJ/kgK and calculate:

411

6.4.1 the volume of air removed per hour; (124.37m3/hr) 6.4.2 the mass of vapour present in the air per hour. (4.41kg/hr)

6.5 A condenser condenses wet steam which enters it at 49.50C and leaves it at

37.70C, while the cooling water absorbs 1838MJ heat per kilogram steam. Take R for air 0.287kJ/kgK and calculate:

6.5.1 the dryness fraction of the wet steam; (0.75) 6.5.2 the air leakage per kilogram of steam. (1.358kg air/kg steam)

6.6 The temperature of the cooling water in a condenser rises from 15.30C to

25.80C while condensing 12 500kg steam per hour, 0.94 dry and at a pressure of 4.5kPa absolute. The temperature of the condensate is 290C and the heat transfer coefficient 4kW/m2 0C. The condenser has two passes and contains tubes with outside diameter 20mm and wall thickness 1.5mm with cooling water at 0.8m/s through it. Calculate the number and the length of the tubes. (1992, 2m)

6.7 18 000kg of steam is condensed per hour by a condenser while air leaks into

it at 0.35kg per 1000kg of steam. The steam enters the condenser dry saturated at 37.70C and the condensate leaves it at 34.60C. The loss of condensate is made up by addition of water at 60C. An air pump, fitted with an air cooler extracts the air from the condenser at 24.10C. Calculate:

6.7.1 the saving in condensate by using a dry air pump; (18.22kg/hr) 6.7.2 the heat supplied by the boiler. (2182kJ/hr)

Tutorial

6.1 A surface condenser is fitted with separate air and condensate outlets. A

portion of the cooling surface is screened from the incoming steam and the air is passes over these screened tubes to the air extraction and becomes cooled below the condensate temperature. The condenser receives 20 000kg/hr of dry saturated steam at 36.20C. At the condensate outlet the temperature is 34.60C and at the air extraction the temperature is 290C. The volume of air and vapour leaving the condenser is 3.8m3/min. Assume constant pressure throughout the condenser, calculate:

6.1.1 the mass of air removed per 10 000kg of steam; (2.63kg) 6.1.2 the mass of steam condensed in the air cooler per minute;

(0.5kg/min) 6.1.3 the heat rejected to the cooling water. (13451kW)

412

Questions relevant to understand and solve this problem: What category of condenser is involved in this question? What information is given and how can this be used? From the given information is it posseble to determine which type of air pump (dry or wet) is used? What is the mass of air removed and how is it determined? What is the mass of steam condensed and how is it determined? What is the relation ship between heat rejected by the steam and heat absorbed by the cooling water? By answering the above questions, you will be able to identify the process. Make a neat sketch of the unit and fill in all the information supplied and the correct positions. This will ensure that the correct values are used during calculations. You can now apply all the formulas pertaining to this process to find the answers.


413

Chapter 7

Combustion

Example 1

A fuel contains 4% hydrogen, 89% carbon, 1% sulphur, 2.5% oxygen and 3.5% ash. The fuel is supplied with 20% excess air. Calculate: 1.1 the air-fuel ratio (A/F); 1.2 the products of combustion for complete combustion; 1.3 The dry products of combustion (POC) by volume. Questions to be asked in order for one to understand the problem and be able to answer the question: Q: what is the air-fuel ratio? A: in combustion calculations this is the ratio of the amount of air (kg) in the

combustion chamber to the amount of fuel (kg) in the combustion chamber. Combustion calculations are always expressed in terms of one kilogram of fuel burnt. If the exact amount of air (ma) is supplied to burn the one kilogram of fuel out completely, it called the stoichiometric air-fuel ratio (theoretical air-fuel ratio). At this point only complete combustion processes are considered. The ratio will be expressed as follows:

ma:1 If more air is supplied than the required amount, then the extra air supplied is

called the excess air (me). To be able to determine the air-fuel ratio the total amount of air (mT) in the combustion chamber must be determined. The total mass of air is made up of the exact amount and the excess air supplied:

mT = ma + me

The air-fuel ratio is now termed the actual air-fuel ratio and expressed as follows: mT:1

Q: how are these different masses of air calculated? A: first the oxygen required for complete combustion of the must be determined. In

each fuel sample there are active elements that require oxygen to take part in the combustion process. Solid and liquid fuels will normally have active elements

414

such as carbon, hydrogen and sulphur. The sulphur content in the fuel is normally kept to a minimum because of its corrosive nature which can damage the engine components. Gaseous fuels will have active element such as methane, hydrogen and carbon-dioxide. The fuel sample in the question is either a solid or liquid fuel looking at the elements that it consists of. In this fuel sample the active elements are hydrogen, carbon and sulphur. To determine the oxygen required for complete combustion of each element a chemical reaction equation and the molecular mass of the element is required:

H2 + O2 » H2O Balance the equation and determine the amount of oxygen per kilogram of

hydrogen required. Molar mass of hydrogen (H) is 1 and that of oxygen (O) is 16.

2H2 + O2 » 2H2O 2*1*2 + 16*2 » 2*(1*2 + 16) 4 + 32 » 36 divide by 4 to express per kilogram of fuel: 1 + 8 » 9

This means that 1kg of hydrogen requires 8kg of oxygen to burn out completely and form water.

Repeat this process for carbon and sulphur. Molar mass of carbon (C) is 12 and that of sulphur (S) is 32. For carbon: C + O2 » CO2 C + O2 » CO2 12 + 32 » (12 + 32) 12 + 32 » 44 1 + 32/12 » 44/12 This means that 1kg of carbon requires 32/12 kg of oxygen to burn out completely and form carbon-dioxide.

415

For sulphur: S + O2 » SO2

32 + 32 » (32 + 32) 32 + 32 » (64) 1 + 1 » 2

This means that 1kg of sulphur requires 1kg of oxygen to burn out completely and form sulphur-dioxide. To determine the total amount of oxygen required, add up the amount of oxygen for each element: mO2 = %H2*8/100 + %C*32/1200 + %S*1/100 (kg oxygen/kg fuel)

Q: what is purpose of the oxygen in the fuel sample? A: this fuel sample contains an amount of oxygen which will react with the

hydrogen at room temperature and pressure (250C and 101.325kPa) to form water. The other active elements will not react with oxygen at these conditions. This means that a certain amount of the hydrogen is already supplied by oxygen. The rest of the hydrogen will require in the supplied air to burn. In the above equation this amount of oxygen in the fuel must then be subtracted from the total amount supplied:

mO2 = %H2*8/100 + %C*32/1200 + %S*1/100 - %O2 in fuel/100 (kg oxygen/kg fuel)

= 4*8/100 + 89*32/1200 + 1*1/100 – 2.5/100

= 2.678 kgO2/kg fuel Q: how is this mass of oxygen converted into mass of air? A: by mass air mainly consists of 23.3% oxygen and 76.7% nitrogen. To determine

the amount of oxygen in the air the following relation ship is used: ma = mO2/23.3*100 = 2.678/23/3*100 = 11.494kg air/kg fuel

416

20% excess air is supplied in this question and therefore the mass of this excess air must be calculated. The following relationship is used:

me = ma*%excess air/100 = 11.949*20/100 = 2.299kg air /kg fuel The total amount of air supplied to the combustion chamber is now calculated: mT = ma + me = 11.949 + 2.299 = 13.793kg air/kg fuel 1.1 To answer the question:

The actual air-fuel ratio is: mT:1 13.793:1 → answer

1.2 Q: what are the products of combustion? A: during the combustion process the active elements react with the oxygen to form

stable products like water, carbon-dioxide and sulphur. The nitrogen in the supplied air does not take part in the combustion process and will leave the combustion chamber with these stable products. All the extra air supplied also contains oxygen which will not have any active products to react with therefore this oxygen will also leave the combustion chamber. All the products that are formed and those that did not take part in the combustion process are named the products of combustion. These products will be tabulated indicating their mass and percentages as follows:

417

Elements Mass /kg fuel

percentage %

N2

mT * %N2 in air/100 + %N2 in fuel/100 13.793 * 76.7/100 + 0

10.579

10.579/14.758*100

71.68

O2

me * %O2 in air/100 2.299 * 23.3/100

0.536

0.536/14.758*100

3.6

CO2

%C * 44/1200 + %CO2 in fuel/100 89 * 44/1200 + 0

3.263

3.263/14.758*100

22.11

SO2

%S * %/100 1 * 2/100

0.02

0.02/14.758*100

0.14

H2O

%H2 * 9/100 + %H2O in fuel/100 4 * 9/100 + 0

0.36

0.36*14.758/100

2.44

Total mass of products: 14.758 100

→ answer Q: what are dry products of combustion by volume? A: the above table gives the product of combustion in kilograms and is called a

mass analysis. If the products of combustion had to be tabulated in terms of volume it is called a volumetric analysis of product of combustion. The same table as above is used, but the molecular mass, volume and percentage volume columns replace the last two columns. The question also specifies dry products which mean that the table should not include hydrogen which forms water during the combustion. The table will look as follows:

418

Elements Mass /kg f M Volume %

N2


10.579

28

10.579/28 = 0.378

0.378/0.469*100 = 80.597

O2

me * %O2 in air/100 2.299 * 23.3/100

0.536

32

0.536/32 = 0.0168

0.0168/0.469*100 = 3.58

CO2

%C * 44/1200 + %CO2 in fuel/100 89 * 44/1200 + 0

3.263

44

3.263/44 = 0.074

0.74/0.469*100 = 15.78

SO2

%S * %/100 1 * 2/100

0.02

64

0.02/64 = 0.000313

0.000313/0.469*100 = 0.067

Total volume of dry products: 0.469 100

→ answer

More relevant questions on this section Q: If no excess air is supplied how does it impact on the calculations of POC? A: In this case the total mass or volume of N2 in the POC will be determined from ma or Va. There will also be no O2 in the POC present, because me is zero. Q: How does too much air influence the performance of an internal combustion engine? A: If there is too much air supplied the mixture is called lean (weak) and the engine will have poor performance in term of power developed. Q: How does too much fuel influence the performance of an internal combustion engine?

419

A: If there is too much fuel supplied, the mixture is called rich and the engine will not be able to burn all the fuel, because there is not enough air supplied for the amount of fuel. This will result in the engine having a high fuel consumption. Q: How is the minimum amount of oxygen determined if different fuels burn completely in a specific ratio? A: Let the two fuels be liquids with a composition: Benzene (C6H6) and octane (C8H18) and the specific ratio for the purpose of explaining C6H6 : C8H18 = 3:4 From first principles: C6H6 + O2 » CO2 + H2O

C6H6 + 7.5O2 » 6CO2 + 3H2O

(12*6 + 1*6) + (7.5*32) » 6*(12 + 32) + 3*(2 + 16)

78 + 240 » 264 + 54 divide by 78 to express per kilogram of fuel:

1 + 3.08 » 3.38 + 0.69 This means that 1kg of benzene requires 3.08kg of oxygen to burn out completely and form water and carbon-dioxide. The amount of benzene present in the sample is not 1kg but 3 parts out of a total of 7 parts. The amount of O2 required is then: 3.08 * 3/7 = 1.32kg C8H18 + O2 » CO2 + H2O

C8H18 + 12.5O2 » 8CO2 + 9H2O

(12*8 + 1*18) + (12.5*32) » 8*(12 + 32) + 9*(2 + 16)

114 + 400 » 352 + 162 divide by 114 to express per kilogram of fuel:

1 + 3.51 » 3.09 + 1.42 This means that 1kg of octane requires 3.51kg of oxygen to burn out completely and form water and carbon-dioxide.

420

The amount of octane present in the sample is not 1kg but 4 parts out of a total of 7 parts. The amount of O2 required is then: 3.51 * 4/7 = 2.01kg The total amount of O2 required for complete combustion of the sample: mO2 = 1.32 + 2.01 = 3.33kg

Q: How are the POC determined in such a case? A: No excess air is supplied therefore me = 0 ma = mO2/23.3 * 100 = 14.29 mT = ma

Elements Mass /kg fuel

percentage %

N2


10.96

10.96/15.28*100

71.72

O2

me * %O2 in air/100 0 * 23.3/100

0

0

0

CO2

CO2 from C6H6*3/7 + CO2 from C8H18 * 4/7 3.38 * 3/7 + 3.09 * 4/7

3.21

3.21/15.28*100

21.01

SO2

0

0

0

0

H2O

H2O from C6H6*3/7 + H2O from C8H18 * 4/7

421

0.69 * 3/7 + 1.42 * 4/7

1.11 1.11/15.28*100 7.26

Total mass of products: 15.28 100

Q: If the fuel is a gas, how does it influence the balancing of the chemical

reaction?

A: Let the two fuels be: Ethane (C2H6) and Propane (C3H8) From first principles: C2H6 + O2 » CO2 + H2O

C2H6 + 3.5O2 » 2CO2 + 3H2O

1 + 3.5 » 2 + 3 equation is per m3 fuel:

This means that 1m3 of ethane requires 3.5m3 of oxygen to burn out completely and form water and carbon-dioxide. C3H8 + O2 » CO2 + H2O

C3H8 + 10O2 » 3CO2 + 4H2O

1 + 10 » 3 + 4 equation is per m3 fuel:

This means that 1m3 of propane requires 10m3 of oxygen to burn out completely and form water and carbon-dioxide.

Q: How will the minimum amount of air in this case be determined?

A: For gaseous fuel the volume of O2 will be determined. Let assume that the sample consists of the following ratio for this explanation: C2H6 : C3H8 = 2:3

The amount of ethane present in the sample is not 1m3 but 2 parts out of a total of 5 parts. The volume of O2 required is then: 3.5 * 2/5 = 1.4m3

The amount of octane present in the sample is not 1m3 but 3 parts out of a total of 5 parts. The volume of O2 required is then:

422

10 * 3/5 = 6m3

The total volume of O2 required for complete combustion of the sample: VO2 = 1.4 + 6 = 7.4m3

Va = VO2/21*100

= 7.4/21*100 = 35.24m3 Q: How will the POC in such a case be determined? A: No excess air is supplied therefore Ve = 0 VT = Va + Ve = Va

Elements Volume /m3fuel percentage %

N2

VT * %N2 in air/100 + %N2 in fuel/100 35.24 * 79/100 + 0

44.61

44.61/50.81*100

87.9

O2

Ve * %O2 in air/100 0 * 21/100

0

0

0

CO2

CO2 from C2H6*2/5 + CO2 from C3H8 * 3/5 2 * 2/5 + 3 * 3/5

2.6

2.6/50.81*100

5.12

H2O

H2O from C2H6*2/5 + H2O from C3H8 * 3/5 3 * 2/5 + 4 * 3/5

3.6

3.6/50.81*100

7.09

Total volume of products: 50.81 100

423

Exercise 7 7.1 A sample of coal gave the following analysis by mass: C 81.9%; H2 4.9%; O2

6%; N2 2.3%; ash 4.9%. Calculate:

7.1.1 the stoichiometric air/fuel ratio; (10.8/1) 7.1.2 the analysis by volume of the wet and dry products of combustion when the air supplied is 25% in excess of that required for complete combustion. (CO2 14.16%, H2O 5.07%, O2 4.04%, N2 76.7%, CO2 14.9%, O2 4.24%, N2 80.9%)

7.2 Calculate the air/fuel ratio for benzene (C6H6), and the wet and dry analysis

of the products of combustion. (13.2/1, CO2 16%, H2O 8.05%, N2 75.8%, CO2 17.5%, N2 82.5%)

7.3 The coal supplied to a boiler has the following composition by mass:

hydrogen 4%, carbon 84%, moisture 5%, the remainder ash. The air supplied is 40% in excess of that required for complete combustion and coal is burned at the rate of 2000kg/hr. Assuming that the specific volume of the flue gases at entrance to the flue stack is 1.235m3/kg and that the maximum permisseble flue gas velocity is 7.75m/s, find the area of the cross-section of the stack at entrance. Assume that air contains 23% oxygen by mass. (1.47m2)

7.4 A furnace gas has the following volumetric analysis: H2 15%, CO 24%, CO2

6%, CH4 12%, O2 3% and N2 40%. Calculate the volumetric analysis of the dry products of combustion with 30% excess air. (N2 81.46%, O2 4.17%, CO2 14.37%)

7.5 The volumetric analysis of a furnace gas is: CO 17.8%, H2 51.3%, CH4

22.5%, O2 0.8%, CO2 5.2% and N2 2.4%. Calculate the air/fuel ratio with 20% excess air. (4.5m3/m3f)

7.6 A fuel with a formula of C7H16 is burned with air. Calculate the minimum

mass and volume of air required for complete combustion of 1kg and 1m3 fuel respectively. (15.1kg, 52.38m3)

7.7 A fuel with a formula of C4H10 is burned with air. Calculate the minimum

mass and volume of air required for complete combustion of 1kg and 1m3 fuel respectively. (21.3kg, 42.86m3)

7.8 Coal with a mass analysis of C 85%, H2 10%, O2 2%, S 1% and 2% ash is

used in a boiler. If 25% excess air is supplied calculate:

424

7.8.1 the stoichiometric air/fuel ratio; (13.12/1) 7.8.2 the percentage composition according to mass of the products of combustion; (N2 72.38%, O2 4.4%, CO2 17.93%, SO2 0.12%, H2O 5.18%) 7.8.3 the volume of the exhaust gas at S.T.P. with R = 0.28kJ/kgK; (13.12m3/kgf) 7.8.4 the heat rejected to the atmosphere by the dry exhaust gas in the form of a vapour with the pressure 120kPa and temperature 186.80C at the chimney. Take Cpex = 1.23kJ/kgK (1662kJ/kgf)

7.9 A fuel contains according to mass carbon 82%, hydrogen 11%, sulphur

1.5%, oxygen 3.5% and the remainder ash. Calculate the higher and lower calorific values of the fuel if the partial pressure of the steam in the exhaust gas is 6kPa. (42.8MJ/kg, 40.4MJ/kg)

7.10 The volumetric analysis of a gas is: CO 24.5%, CO2 4.5%, H2 5.5%, CH4

34.5%, O2 2.2% and N2 28.8%. Calculate the higher and lower calorific values of the fuel per m3, if every m3 vapour that formed absorbs 2.4 MJ of heat. (16.62MJ/m3, 16.49MJ/m3)

Tutorial

7.1 A sample of coal gave the following analysis by mass: C 81.9%; H2 4.9%; O2

6%; N2 2.3%; ash 4.9%. Calculate:

7.1.1 the stoichiometric air/fuel ratio; (10.8/1) 7.1.2 the analysis by volume of the wet and dry products of combustion when the air supplied is 25% in excess of that required for complete combustion. (CO2 14.16%, H2O 5.07%, O2 4.04%, N2 76.7%, CO2 14.9%, O2 4.24%, N2 80.9%)


What information is given and how can this be used to determine the type of fuel? What is a stoichiometric air/fuel ratio and what is an actual air/fuel ratio? What is a volumetric analysis of POC? What is the difference between a dry and wet analysis? By answering the above questions, you will be able to identify the type of fuel. You can now apply all the formulas pertaining to this process to find the answers. When doing a mass or volumetric analysis of POC, a table format is suggested.

425


426

Revision exercise Apply your enquiry based learning skills which you have been developing throughout the course to solve the following problems. At this point you should also be able to formulate questions and answers based on your knowledge gained in this course. This will also be an exercise to indicate to you the effectiveness of your learning process in terms of knowledge retention, understanding and application in solving problems. Briefly list all your questions with answers below each question before solving the problem: 1. During a moulding process, air is compressed from a pressure of

150kPa to a pressure of 500kPa and a temperature of 400K. During this process the volume is reduced to one third its original value. Calculate:

1.1.1 the value of the index of compression ‘n’. Round-off to three decimals; (2) 1.1.2 the work done during compression per kilogram of air; (4) During the second stage of the process is reversed and the air is expanded polytropically to double the initial volume. Calculate: 1.1.3 the pressure at the end of expansion; (2) 1.1.4 the temperature at the end of expansion; (2) 1.1.5 heat flow during expansion per kilogram of air; (6)

1.1.6 Sketch a neat fully detailed pressure-volume diagram. Shade the area which represents the compression work done. (5) [21] List your questions and answers below:

427

2. The pressure of a certain gas in the cylinder of an engine rises from 75kPa to 1.15MPa during the compression stroke. During this stroke the volume decreases from 0.5m3 to 0.06m3 and the compression takes place according to the law PVn = constant. The initial temperature of the gas is 390C. Assume R = 0.285kJ/kgK for the gas and Cv = 0.715kJ/kgK. Calculate:

2.1.1 the value of the index of compression ‘n’; (3) 2.1.2 the work done during compression; (2) 2.1.3 the mass of the gas in the cylinder; (2) 2.1.4 the change in internal energy; (4) 2.1.5 the heat exchange with the surroundings. (2) 2.1.6 Sketch a fully detailed PV-diagram indicating clearly the area which represents the work done. (4) 2.2 A quantity of gas occupies a volume of 1.4m3 at a pressure of 96.5kPa and temperature of 930C. The gas is compressed according to the law PV1.25 = constant to a pressure of 860kPa, and then heated at constant volume to a pressure of 3.1MPa. Take Cp = 1.255kJ/kgK and R = 0.29kJ/kgK. 2.2.1 Draw a fully detailed PV-diagram of the process and indicate the area which represents the polytropic work done. (5) 2.2.2 Calculate the volume and temperature at the end of heat addition. (6) [28] List your questions and answers below:

428

3. In a steady flow system, 1kg of fluid per second enters the control volume at a pressure of 1 bar and it leaves the system at a pressure of 10bar. The inlet and exit velocities are 40m/s and 20m/s respectively. During the process 36000kJ of heat is transferred per hour to the control volume. The rise in enthalpy of the fluid is 15kJ/kg. Calculate the power developed by the system. [4] List your questions and answers below:

429

4. A steam turbine receives a steam flow of 25 000 kg/hr and its power output is 500 kW. Neglecting any heat loss from the turbine, find the change in specific enthalpy of the steam flowing through the turbine taking inlet and outlet velocity as 80 m/s and 300 m/s. (3) List your questions and answers below:

430

5. Determine how much energy is required to change 3.5kg of water at 150C into superheated steam in a rigid vessel. The degree of superheat is 300C at a pressure of 500kPa. [5]

List your questions and answers below:

431

6. Steam at a pressure of 400kPa and with a dryness fraction of 0.85 expands according to the law PV1.2 = C to a volume of 0.7m3/kg. Determine:

6.1 the pressure at the end of expansion; (3) 6.2 the condition of the steam at this point; (2)

6.3 the heat flow during this process. (6)

6.4 Draw a pressure-volume and a temperature-entropy diagram of this

process. Also indicate the area which represents the work done and heat flow.(Hint compare entropy values) (6)

[17] List your questions and answers below:

432

7. A combined separating and throttling calorimeter was used to determine the dryness fraction of the steam in the main steam pipe in which the pressure was 860kPa. The observations were:

Water collected in separator - 0.3kg/min

Steam condensed after throttling - 10kg/min Steam pressure after throttling - 140kPa Steam temperature after throttling - 1300C Specific heat capacity of steam - 2.1kJ/kgK

Determine: 7.1 the dryness fraction of the steam in the main steam pipe. (8) 7.2 Draw the throttling process on a Mollier chart with all relevant detail. (3)


433

8. A boiler fitted with a super-heater generates 1800kg of steam per hour at a pressure of 11bar and temperature of 2500C, from feed water at 900C. The dryness fraction of the steam as it enters the super-heater is 0,98. The has a calorific value of 26 000kJ/kg, and is consumed at a rate of 467kg/hr. Calculate:

8.1 the thermal efficiency of the boiler; (4) 8.2 the percentage of the fuel heat supplied in the combustion chamber,

absorbed by the steam in the super-heater tubes; (5)

8.3 the equivalent evaporation from and at 1000C. Briefly discuss the meaning of this value. (3) [12] List your questions and answers below:

434

9. A steam plant consists of an economiser, boiler, super-heater and air pre-heater. The coal used has a calorific value of 3600kJ/kg and the ratio of air to fuel by mass is 18:1. Air enters the air pre-heater at 160C and leaves at 200C. Feed water enters the economiser at 460C and leaves at 1800C. Steam enters the super-heater 0.97 dry and leaves at 2600C. The pressure in the boiler is 2MPa. Steam is generated at the rate of 2300kg/hr. The specific heat capacity for air is 1.005kJ/kgK and that for the flue gas is 1.045kJ/kgK. The fuel consumption is 2000kg/hr.

9.1 Make a neat line sketch of the plant indicating the flow of air, steam and flue gases. (5)

9.2 Calculate the heat transfer per kilogram of fuel used, in the economiser, boiler, super-heater and air pre-heater. (9)

9.3 Calculate the plant efficiency. (2) 9.4 Calculate the equivalent evaporation from and at 1000C per kilogram fuel burnt. (2)

9.5 Calculate the temperature of the flue gases leaving the combustion chamber. (2)


435

10 Consider a steam power plant that operates on a simple ideal Rankine cycle and has a net power output of 20MW. Steam enters the turbine at 7MPa and 5000C and is cooled in the condenser at a pressure of 10kPa by running cooling water from a lake through the tubes of the condenser at a rate of 1750kg/s. 10.1 Illustrate this process on a temperature-entropy diagram with all relevant detail. (3) Determine: 10.2 the Rankine efficiency of the cycle; (5) 10.3 the mass flow rate of steam; (2) 10.4 the temperature rise of the cooling water (2)


436

11. A condenser receives wet steam at a pressure of 7kPa. The air leakage is 20kg/hr and take R = 0.287kJ/kgK. Mass of cooling water is 1140kg/min

and mass of the condensate is 2360kg/hr at a temperature of 36.20C. The barometer reading is 641mmHg and the rise in the cooling water temperature is 18.10C.

Calculate: 11.1 the volume of air removed per minute if: 11.1.1 a wet air pump is used; (4) 11.1.2 a dry air pump is used with a suction tube temperature of 32.90C; (4) 11.2 the dryness fraction of the exhaust steam; (3) 11.3 the vacuum gauge reading; (2) 11.4 the number of tubes for this two pass surface condenser, if the internal diameter of the pipes is 13 mm and the water speed is 3 m/s. (3) [16]


437

12. The air leakage into a surface condenser operating with a steam turbine

is estimated as 84kg/hr. The vacuum near the inlet of the air pump is

700mmHg when the barometer reads 760mmHg. The temperature at

the inlet of the air pump is 200C. Calculate:

12.1 the minimum capacity of the air pump; (7)

12.2 the dimensions of the reciprocating air pump to remove the air if it runs at 200rpm. Take diameter: stroke = 3:2 and the

volumetric efficiency as 100 %; (4)

12.3 the mass of vapour extracted per minute. (3)

12.4 If the air suction spout temperature is reduced to 160C, determine

the how much condensate is saved over a period of 30 days with the

plant running continuously. (7)

[21]


438

13. During a test, the following analysis by mass were obtained from a given sample:

4% oxygen, 7% sulphur, 5% hydrogen, 84% carbon Air contains 23% oxygen by mass and the atomic masses are: carbon - 12, sulphur - 32, hydrogen - 1, oxygen - 16, nitrogen - 14 The calorific value of carbon is 33.7MJ/kg, hydrogen is 146MJ/kg and sulphur 9.5MJ/kg. Calculate: 13.1 the oxygen required to burn 3kg of this fuel; (4) 13.2 the air required; (2) 13.3 the air required if 30% excess air is supplied; (4) 13.4 the calorific value of this fuel per kilogram of fuel; (4) 13.5 the dry products of combustion, considering the 30% excess air. (8)


439

14. An experiment was performed with a fuel mixture consisting of the following: 44% C8H18 (n-octane), 1% S, 55% C6H6 (benzene), 5% O2 Air contains 23% oxygen by mass and the atomic masses are: carbon - 12, sulphur - 32, hydrogen - 1, oxygen - 16, nitrogen - 14 Calculate from first principles (show chemical reactions): 14.1 the air required; (10) 14.2 the amount of nitrogen released into the atmosphere after complete combustion of each kilogram of this fuel; (1) 14.3 the products of combustion, by volume. (10) [21] List your questions and answers below:

440

Appendix 13 – Student responses to interviews

Item 1: The group sessions were very enjoyable.

Positive responses:

Groups sessions were very enjoyable/I have

enjoyed groups sessions/it was very

enjoyable

20 (N = 20)

Neutral or negative responses:

Groups sessions were not enjoyable

0 (N = 20)

Item 1a: The group sessions motivated you to come prepared to class.

Positive responses:

So that I can work together and not be left

behind/I will have to explain what I

understand/it was like a competition and

nobody wants to look stupid

18 (N = 18)


Group sessions did not motivate me to come

prepared to class

18 (N = 18)


Positive responses:

In the group you use English so you become

use to the language/I can explain to others

and we can share/because I have to talk to

others and on my own I do not communicate

18 (N = 19)


It was difficult to take part in the group

sessions because I am a shy person

1 (N = 19)

441


Positive responses:

The questions given help me to analyse the

problems/I have to ask myself what do I

understand about the problem/we were

taught how to tackle problems and how to

get answers to our questions/when I work

on my own I try to ask myself questions

about what is given and what do I

understand about the problem

20 (N = 20)


The enquiry based sessions did not help me

to analyse problems more effectively

0 (N = 20)

Item 3: When working alone the enquiry based approach helped me to analyse problems

effectively.

Positive responses:

I used the information which I have learned

during the group sessions/I follow the same

approach in analysing the question that we

have used in group sessions/I asked myself

similar questions to those that we have

asked during group sessions, when working

alone

20 (N = 20)


The enquiry bases approach did not help me

to solve problems when working alone

0 (N = 20)


Positive responses: Neutral or negative responses:

442

We share information and analyse the

problem so we understood what to do/group

discussions helped us to understand the

work/we were able to use questions to

analyse new problems

20 (N = 20)

This method did not help me to understand

the work and I still have to memorise it

0 (N = 20)

Item 5: This method helped me develop the ability to solve problems on my own.

Positive responses:

When alone use the same approach that

have been used during group sessions,

analyse the new problem by asking

questions/you have many methods of

approaching the problem and how to ask

questions that leads you to ways to solve the

problem/asking question gives me more

information about a problem

20 (N = 20)


This method did not help me to develop the

ability or to improve my ability to solve

problems

0 (N = 20)

Item 6: The Thermodynamics booklet with questions and answer helped me to understand

the work better.

Positive responses:

The layout and explanations in the booklet

helped us to understand new work better/


The Thermodynamics booklet did not help to

understand the work better

0 (N =20)

443

Item 7: The Thermodynamics booklet’s additional questions and answers helped me to

understand and analyse new problems better.

Positive responses:

The additional questions in the booklet

assisted us to analyse new problems/the

additional questions helped me to gain more

information about the problem

4 (N = 4)


The booklet with the additional questions

and answers did not help to understand and

analyse new problems better

0 (N = 4)

Item 8: This method can help me to understand other courses better.

Positive responses:

Yes because in other course the lecturer just

talks and walk out/ in other subjects you

don’t get a chance to analyze the question

but you just memorize the formulas and

substitute it, but the core information you

don’t know

20 (N =20)


This method cannot help to understand

other course better

0 (N = 20)

Item 9: Any positive or negative comments on your overall experience compared to the

traditional teaching method.

Positive responses:

I think this one is very good, because when

you are going to school or class what you

need most is understanding/now I learnt


Any negative comments on your overall

experience

0 (N =20)

444

how to tackle questions I learned to do

things

20 (N = 20)

Item 10: Did this method give you positive attitude towards the course?

Positive responses:

because in understanding Thermodynamics

that made me enjoy it a lot in fact I realized

it is a very exciting course/ I mean you

always like something that you are good at/

it gave me a way of how to approach a sum

how to ask questions that are relevant that

will lead you to answer the question

20 (N = 20)


This method did not give me a positive

attitude towards the course

0 (N = 20)

445

Appendix 14 – Electronic Thesis & Dissertations (ETD) and Plagiarism

Requirements


DIRECTORATE OF POSTGRADUATE STUDIES

MANDATORY CONSENT FORM: ELECTRONIC THESES & DISSERTATIONS (ETD) AND PLAGIARISM

REQUIREMENT (For postgraduate research outputs from 2009 September)

THE STUDENT AND SUPERVISOR CONSENT FOR PUBLICATION OF ELECTRONIC RESEARCH OUTPUT ON INTERNET

AND WSU INTRANET

FACULTY: EDUCATION

QUALIFICATION NAME: DOCTOR OF EDUCATION ABBREVIATION: D.Ed. YEAR: 2012

STUDENT’S FULL NAME: CHRISTOFFEL LOUW STUDENT NUMBER: 209187158

TYPE OF RESEARCH OUTPUT: THESIS

TITLE OF THE RESEARCH OUTPUT: ‘THE EFFECT OF A GUIDED ENQUIRY BASED LEARNING APPROACH ON

MECHANICAL ENGINEERING STUDENTS’ UNDERSTANDING OF THERMODYNAMICS’

CONSENT: I HEREBY GIVE MY CONSENT TO WALTER SUSULU UNIVERSITY TO PUBLISH MY RESEARCH OUTPUT FOR

THE QUALIFICATION ABOVE ON THE WSU INTRANET AND INTERNET. I CERTIFY THAT TO THE BEST OF MY

KNOWLEDGE, THERE IS NO PLAGIARISM IN THE RESEARCH OUTPUT AS SUBMITTED. I HAVE TAKEN REASONABLE

CARE TO ENSURE THAT THE RESEARCH OUTPUT MEETS THE QUALITY LEVEL EXPECTED FOR THE PRESENT

QUALIFICATION LEVEL BOTH IN TERMS OF CONTENT AND TECHNICAL REQUIREMENTS. I FULLY UNDERSTAND THE

CONTENTS OF THIS DECLARATION.

___________________________________ _______________________________

SIGNATURE OF STUDENT DATE

ENDORSEMENTS BY:

SUPERVISOR:

FULL NAME: ____________________________________SIGNATURE:___________________________

DATE: _______________

446

CO-SUPERVISOR(S):

1 FULL NAME: _________________________________SIGNATURE:________________________________

DATE: _______________

2. FULL NAME: ________________________________SIGNATURE:___________________________________

DATE: _______________

the effect of a guided enquiry based learning …

Documents