performance and design analysis of domestic lpg stove

A

Project Reporton

PERFORMANCE AND DESIGNANALYSIS OF DOMESTIC LPG STOVE

Submitted in Partial Fulfillment of

the Requirements for the Degree

of

Master of Engineering

in

Machine Design

to

North Maharashtra University, Jalgaon

Submitted by

Jagruti R. Surange

Under the Guidance of

Prof.N.K.Patil

DEPARTMENT OF MECHANICAL ENGINEERING

SSBT’s COLLEGE OF ENGINEERING AND TECHNOLOGY,

BAMBHORI, JALGAON - 425 001 (MS)2014-2015

SSBT’s COLLEGE OF ENGINEERING AND TECHNOLOGY,

BAMBHORI, JALGAON - 425 001 (MS)

DEPARTMENT OF MECHANICAL ENGINEERING

CERTIFICATE

This is to certify that the project entitled Performance and Design Analysis of Do-

mestic LPG Stove, submitted by Jagruti R. Surange in partial fulfillment of the

degree of Master of Engineering in Machine Design has been satisfactorily carried out

under my guidance as per the requirement of North Maharashtra University, Jalgaon.

Date: January 20, 2015

Place: Jalgaon

Prof.N.K.Patil

Guide

Prof. Dr. Dheeraj. S. Deshmukh Prof. Dr. K. S. Wani

Head Principal

SSBT’s College of Engineering and Technology, Bambhori, Jalgaon (MS) i

DECLARATION

I hereby declare that the work presented in this project entitled “Per-

formance and Design Analysis of Domestic LPG Stove”, submitted to the

Department of Mechanical Engineering, SSBT’s College of Engineering and Technol-

ogy, Bambhori, Jalgaon - 425 001 (MS), in partial fulfillment of the degree of Master

of Engineering in Machine Design of North Maharashtra University, Jalgaon, is my

original work.

Wherever contributions of others are involved, every effort is made to indicate this

clearly, with due acknowledgement and reference to the literature.

Date: January 20, 2015

Place: Jalgaon

(Jagruti R. Surange)

In my capacity as guide of the candidate’s project, I certify that the above statements

are true to the best of my knowledge.

(Prof.N.K.Patil)

SSBT’s College of Engineering and Technology, Bambhori, Jalgaon (MS) ii

Acknowledgements

The compilation of this Project would not have been possible without the support and

guidance of the Prof. N.K.Patil With my deep sense of gratitude; I thank my respected

teachers for supporting this topic of my Project.

My deep and most sincere feeling of gratitude to the Head of Department Prof. Dr. D. S.

Deshmukh who very kindly allowed me to work on this interesting topic. This Project report

provides me with an opportunity to put into knowledge of advanced technology. I thereby

take the privilege opportunity to thank all the Teachers for help and guidance for this study.

Above all I would like to put on record my special thanks to Principal Dr. K. S. Wani,

S.S.B.T’s, College of Engineering and Technology, Bambhori, Jalgaon (Maharashtra). and I

would like to express my gratitude with a word of thanks to all of those who are directly or

indirectly associated.

I would like to put on record my special thanks to Prof. Dr. S. P. Shekhawat, Prof. P.G.

Damle, Prof. D.B. Sadaphale, Prof. P. N. Ulhe,Prof. P.M. Solanki, Prof. D. C. Talele,

and Prof. K. G. Girase for their valuable co-operation. The experimental work is supported

by S.S.B.T’s, College of Engineering and Technology, Bambhori, Jalgaon (Maharashtra),

India. I express my gratitude to the Management, Principal and Director of Research and

Development of the institute for support and encouragement. At last I am also thankful to

my parents and son Rupesh for their valuable support to me for completion of project.

Jagruti R. Surange

SSBT’s College of Engineering and Technology, Bambhori, Jalgaon (MS) iii

Contents

Acknowledgements iii

Abstract 1

1 Introduction 3

1.1 Background of study . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

1.2 Need of Project . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

1.3 Scope of the Project . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

1.4 Burner . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

1.5 LPG: The Major domestic Fuel for Cooking . . . . . . . . . . . . . . . . . . 5

1.6 LPG Stove and Conventional Burner Structure . . . . . . . . . . . . . . . . . 7

1.7 Summary of the Project . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

2 Literature Review 10

2.1 Objectives of the Project . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

3 Design Analysis of Burner 20

3.1 Fuel Jet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

3.2 Behavior of free (unconfined) and confined jet . . . . . . . . . . . . . . . . . 22

3.3 Importance of primary and secondary air in Burner Design . . . . . . . . . . 23

3.4 Different Parts of a Burner System . . . . . . . . . . . . . . . . . . . . . . . 23

3.5 Injector Orifice . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

3.6 Gas flow through an injector orifice . . . . . . . . . . . . . . . . . . . . . . . 24

3.7 Combustion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

3.8 Air Entrainment in the burner system . . . . . . . . . . . . . . . . . . . . . . 27

3.9 Throat size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

3.10 Mixing Tube . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

3.11 Burner Top . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

3.12 Burner Ports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

SSBT’s College of Engineering and Technology, Bambhori, Jalgaon (MS) iv

3.13 Burner port design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

3.14 Flames . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

3.14.1 Burner Manifold (Combustion chamber) . . . . . . . . . . . . . . . . 34

3.14.2 Burner Top . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

3.15 Design Calculations for conventional burner . . . . . . . . . . . . . . . . . . 35

4 Performance analysis of conventional LPG stove Burner 40

5 CFD Analysis of Burner 47

6 Results and Discussion 55

7 Conclusion 59

Bibliography 61

SSBT’s College of Engineering and Technology, Bambhori, Jalgaon (MS) v

List of Tables

3.1 Star rating of stoves to be labeled [22] . . . . . . . . . . . . . . . . . . . . . 20

3.2 Theoretical and empirical correlations to estimate the vertical length of lam-

inar flames[11] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

4.1 Properties of LPG Gas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

4.2 Burners specification under considerations . . . . . . . . . . . . . . . . . . . 42

4.3 Burner Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

4.4 Experimental Results for cold Burner . . . . . . . . . . . . . . . . . . . . . . 44

4.5 Experimental Results for Warm Burner . . . . . . . . . . . . . . . . . . . . . 46

4.6 Experimental results for cold and warm burners . . . . . . . . . . . . . . . . 46

5.1 Comparison of Experimental results with CFD results . . . . . . . . . . . . . 54

SSBT’s College of Engineering and Technology, Bambhori, Jalgaon (MS) vi

List of Figures

1.1 consumption in Urban and Rural India[5] . . . . . . . . . . . . . . . . . . . . 6

1.2 Parts of a LPG stove . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

3.1 Mixing of air-fuel in a burner [31] . . . . . . . . . . . . . . . . . . . . . . . . 21

3.2 Spreading of an axis-symmetric jet in the surrounding[31] . . . . . . . . . . . 22

3.3 Entrainment of products of combustion in the jet. [31] . . . . . . . . . . . . 22

3.4 Combustion Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

3.5 Mixing tube and Burner Assembly . . . . . . . . . . . . . . . . . . . . . . . 29

3.6 Typical flame of a gas burner . . . . . . . . . . . . . . . . . . . . . . . . . . 31

3.7 Flame lift off . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

3.8 Flame flash back . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

3.9 Stability Diagram for Manufactured Gas Flames, displaying flashback, liftoff

and yellow tipping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

3.10 General combustion chamber structure of LPG stove burner. . . . . . . . . . 34

3.11 Possible flame arrangements . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

4.1 Experimental setup for performance analysis of conventional burner. . . . . . 43

5.1 2-D drawing for conventional burner . . . . . . . . . . . . . . . . . . . . . . 48

5.2 Burner Models a) Conventional Burner b) Burner B1 c) Burner B2 . . . . . 49

5.3 Create Named Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

5.4 Model after Meshing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

5.5 Model in Meshing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

5.6 Model Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

5.7 Boudary condition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

5.8 Number of iteratiions and calculation of solution . . . . . . . . . . . . . . . . 52

5.9 Scaled Residuals After solution . . . . . . . . . . . . . . . . . . . . . . . . . 53

5.10 Plot for Flame Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

5.11 Flame Temp experimental and Computational . . . . . . . . . . . . . . . . . 54

SSBT’s College of Engineering and Technology, Bambhori, Jalgaon (MS) vii

6.1 Effect of warm burner on thermal efficiency for CB . . . . . . . . . . . . . . 56

6.2 Effect of warm burner on thermal efficiency for B1 . . . . . . . . . . . . . . . 57

6.3 Effect of warm burner on thermal efficiency for B2 . . . . . . . . . . . . . . . 57

SSBT’s College of Engineering and Technology, Bambhori, Jalgaon (MS) viii

Abstract

As Liquefied petroleum gas (LPG) offers clean cooking environment as well as high heat

content, it is most popular fuel for domestic and commercial cooking in rural and urban

India. Along with rising population, increasing demand of LPG in India and its depleting

resources need for performance improvement in LPG cook stoves raised importance to design

stoves with improved higher efficiency. Designed thermal efficiency of LPG stove is 65-68

%. The work is relevant to study the parameters affecting the performance of a domestic

LPG stove Burner. Based on designed thermal efficiency and flame stability criterion, the

conventional burner is design is analyzed for its dimensions, and based. Number of ports

and spacing between the ports also known as quenching distance are the variables considered

for improvement of burner.

Design analysis of a conventional burner is carried out for its designed efficiency at given

power output. Burner top design is the basic intension for this work. Which ultimate give

arrangement of burner ports to give a continuous flame with complete combustion. Total

port area is the key decision factor.

For conventional burner, thermal efficiency is evaluated using water boiling test sug-

gested by the BIS (IS: 4246:2002). The test has been performed for three brass burners,

one of them is named conventional burner, and other two named as burners B1 and B2.

Thermal efficiency of these three is about 53 %, 49 % and 51 % respectively. All the three

burners were different in port numbers only, with 200, 180 and 165 no. of ports for CB

(Conventional Burner), B1 and B2. Flame blow off takes place in Burner B1. Port area and

ambient temperatures shows influence on burner performance.

The effect of warm (preheated) burner surface also shows a considerable gain in thermal

efficiency. For burner B1, about 11 % gain is observed when tests are performed for warm

burner. Maximum thermal efficiency for burner B2 is found about 61 % when used in warm

condition. All the burners showed accountable rise due to effect of warm burner surface.

SSBT’s College of Engineering and Technology, Bambhori, Jalgaon (MS) 1

Chapter 1

Introduction

1.1 Background of study

Increased standard of living and rising population in India has raised the energy consump-

tion in day to day life. But limited source of fossil fuels with increasing demand resulted in

rising prices. In order to face the upcoming challenge of shortcoming of fuels, efforts in the

field of improved performance of all apparatus in the field of combustion are necessary.

Being one of the primary needs of human being, conservation of cooking fuel is the prime

need. Traditional sources of cooking fuels are used rural India with first priority. But in

urban area, modern civilization it is shifted towards use of a clean, safe, efficient fuel. LPG

is the most commonly used cooking fuel in urban area now a-days. Compared with other

fuels, LPG is the most efficient fuel, but still in order to attain better utilization of this vital

fuel efforts are required.

Increased standard of living and rising population in India has raised the energy consump-

tion in day to day life. But limited source of fossil fuels with increasing demand resulted in

rising prices. In order to face the upcoming challenge of shortcoming of fuels, efforts in the

field of improved performance of all apparatus in the field of combustion are necessary.

Being one of the primary needs of human being, conservation of cooking fuel is the prime

need. Traditional sources of cooking fuels are used rural India with first priority. But in

urban area, modern civilization it is shifted towards use of a clean, safe, efficient fuel. LPG

is the most commonly used cooking fuel in urban area now a-days. Compared with other

fuels, LPG is the most efficient fuel, but still in order to attain better utilization of this vital

fuel, further improvements are needed.


In order to achieve better utilization of a fuel, performance of a stove becomes an im-

portant to consider. It becomes the major criterion to evaluate any apparatus. In LPG

stove performance of a stove is directly measured by its thermal efficiency, which gives direct

relation with a burner.

1.2 Need of Project

In the era of energy conservation, every fuel drop is valuable. In order to achieve their

better utilization, they must be used to their highest level of performance. Rising cost with

depleting sources of this vital fossil fuel, more efforts are required to accelerate the fuel

utilization. Any fuel can perform better when the appliance burning it has proper design;

hence ultimately for better utilization of fuel, burner design is important in a cooking stove

performance. Hence it is necessary to study the factors affecting a burner design and to

modify the existing burner for improved efficiency.

1.3 Scope of the Project

This research work shall focus on design analysis and performance evaluation of burners for

determination of features affecting thermal efficiency experimentally. The burner is modeled

using tool CATIA V5, and flow of fuel will be analyzed with computational method CFD

(Computational Fluid Dynamics). Validation of CFD results with experimental results.

1.4 Burner

A gas burner is a ”Device which enables a chemical reaction of fuel and oxidizer

(usually Oxygen from air) to produce heat in a controlled way.” In another word

it can be described as a device to generate a flame to heat up products using gaseous fuels.

A burner a mechanical device that performs following functions-

• It supplies required amount of fuel and air to combustion chamber.

• Creates condition for rapid mixing of fuel and air

• Produces a flame which transfers thermal energy to application


There are two types of burners as per fuels used, liquid fuel and gaseous fuel burners.

Based on their applications industrial burners and domestic burners are the anther criterion

of classification. In general all gas burners in domestic appliances are of blue flame type or

Bunsen type and are commonly referred as atmospheric burners or blue flame burners. [12]

Primary requisite of any appliance is that, it should be capable to burn the fuel completely.

It is observed that performance of any combustion apparatus decided by its design rather

than the fuel being used. For improved efficiency of any appliance, its burner must be center

of design purpose.

1.5 LPG: The Major domestic Fuel for Cooking

LPG is the abbreviation for liquefied petroleum gas. It is a light distillate obtained from

the processing of natural gas and crude oil. Its normal components are propane (C3H8) and

butane (C4H10)(Propane 57-60 %, Butane 40-43 %) . Other hydrocarbons and components

other than hydrocarbons may also be present in small concentrations.

It is an ideal energy source for a wide range of applications as it can be easily condensed,

packaged, stored and utilized. An American scientist Dr. Walter Snelling, discovered Liq-

uid petroleum gases in 1912, when realized that these gases could be changed into liquids

and stored under moderate pressure. Being low-carbon content, low-polluting fuel, reduced

greenhouse gas emissions, now a-days LPG has became a prime gaseous fuel for domestic

purpose world-wide. Along with cooking LPG has some applications as auto-fuel, Residen-

tial space heating, Residential Water Heating, Distributed Power Generation etc. [1]

Now a day’s LPG is known as: ”The Ideal Fuel for Modern Living” some additional

advantages of using LPG as a fuel gas are - availability globally, environmental benefits,

its natural by-product origin, diverse application and transportation flexibility, LPG plays

a pivotal role in the transition towards a more secure, sustainable and competitive energy.

Being more than 1000 applications of LPG, in India, it is the most widely-used domestic

fuel for cooking. LPG is the most widely-used alternative to automotive fuel. According to

a survey of Potential Market: Domestic Segment in Rural Areas, LPG connections are in

urban and rural areas are 83.81nd 31.2 million respectively [29]

India ranks fourth largest consumer of LPG in the world after USA, China and Japan.

In India LPG is majorally marketed by the three main public sector oil marketing companies

(OMCs), these are Bharat Petroleum Corporation Limited (BPCL), Indian Oil Corporation

Limited (IOCL), and Hindustan Petroleum Corporation Limited (HPCL). Around 80 %


LPG consumption is in domestic purpose.[ffs-india].Out of these major consumer is urban

household.

Figure 1.1: consumption in Urban and Rural India[5]

The industry of domestic LPG stove has grown considerably over the last 18 years and

offers a wide range of products in cooking stoves that is:

1. Gas stove with one burner,

2. Gas stove with two burners,

3. Gas stove with two burners, one grill also called as cooking grill,

4. Gas stove with three burners,

5. Gas stove with four burners etc.

Having a plenty of advantages, another side of coin is LPG is more explosive as it is

pressurized, its explosive power equivalent to 7 sticks of dynamite having a capacity to

destroy entire household and surrounding. [30] For this serious precaution, the Oil Industry

and LERC ( LPG Equipment Research Centre, Bangalore) focused in ensuring domestic

safety, actively involved in developing the following Indian Standards:

• IS- 14612: Specification for Commercial Burners

• IS- 14899: Specification for LPG containers for Automotive use

• IS- 15100: Specification for Multi-function Valve assembly for fixed cylinders for auto-

motive use.


• IS- 9573: Specification for LPG Rubber Hose (Developed specifically on LERC request)

• IS- 15558: Specification for instant gas water heaters.

Though this is an ideal fuel for domestic purpose, increasing demand with increased

population may create the shortcoming of LPG in future. As LPG is a non-renewable and

limited source of energy, we must try to conserve this environment friendly fuel and try

making its optimum use. A fuel is said to be work effectively if it utilized to its maximum

efficiency without emitting harmful byproducts to environment.

1.6 LPG Stove and Conventional Burner Structure

LPG stove is a simple and user friendly appliance for direct combustion. The body of the

stove is made of steel sheet for strength and durability and it is supported by adjustable

rubber grommets. Gas consumption in stove is regulated by means of a heat resistant knob.

A simmer orifice is provided in the gas tap to reduce the gas consumption rate within the

range. These stoves are available in variety of ignition system (Spark ignition, auto ignition),

no. of burners. Burner of a LPG stove is specified by premixed and multi-holed burning

ports type. Major parts of a LPG stove are gas supply tube (piping and fitting for use with

Liquefied Petroleum Gas at 30 gf/cm2 gas inlet pressure), gas taps and throat, gas mixing

tube/manifold, burner pan supports, single or multiple burners. The general structure of

domestic LPG with to burner stove is as given in the Figure 1.2

Figure 1.2: Parts of a LPG stove


Stove is connected to cylinder through a low pressure regulator. Regulator reduces pres-

sure from cylinder and supplied this reduced pressure to burner when needed. The gas

burner is connected to injector through a mixing tube. When gas supply is switched on,

LPG from the cylinder comes to a fixed injector orifice with certain speed; from orifice gas

moves towards mixing tube having two ports for primary air supply. As gas jet enters with

high velocity, it creates low static pressure in mixing tube and causes suction of primary air.

In mixing tube, gas and air mixes and passes to mixing chamber and then comes out in jet

form through burner ports. When the flame is propagated by spark ignition, secondary air

is supplied to combustion zone from bottom of mixing chamber.

Thermal efficiency of a stove decides its performance. As thermal efficiency of any stove

is nothing but the thermal efficiency of the burner. Hence if it is needed to improve per-

formance of any stove, burner should given first priority. Stoves are labeled and rated by

their performance in the form of thermal efficiency. Almost all stoves have designed thermal

efficiency 65-68 %. But actually it observed less than 50 %. All LPG appliances are manu-

factured and tested as per BIS (IS 4246: 2002). In order to utilize the fuel to its maximum

output, it’s necessary to look at different modification to improve performance of a stove. In

order to achieve higher thermal efficiency, it’s necessary to find out parameters affecting it.

1.7 Summary of the Project

The project is summarized as,

• Chapter 1 discusses about an background, objective, need, scope of project. intro-

duction to burner, LPG as the the major domestic Fuel for Cooking, LPG Stove and

Conventional Burner Structure.

• Chapter 2 contains literature review.

• Chapter 3 contains details of design analysis of a conventional burner used for cooking

stoves based on the power output of requirements. The design and combustion of

fuel gas are two different mechanisms to be blended in order to get better utilization

of fuel with satisfactory heat output. A conventional burner is designed for circular

shape combustion chamber. Burner port size, number of ports and distance between

ports are needed to consider for a burner design. The total port area is calculated

and this becomes a basic decision key for selection between number of ports and the

size of ports. The flame stability characterization is the decision factor for selecting an

optimum design based on power per unit area per port.


• Chapter 4 contains details of experimental method used, various measurement tech-

niques, equipments used with their characteristic features etc.

• Chapter 5 deals with computational method for flow analysis of LPG stove through

the burner

• Chapter 6 contains results and discussion.

• Chapter 7 contains an overview and concluding remarks.


Chapter 2

Literature Review

Pankaj P. Gohil et al. [1] investigate experimentally the performance of conventional LPG

cooking stove. They evaluate performance of cooking stove by using water boiling test and

emission test according to IS 4246:2002. Water boiling test gives thermal efficiency of stove

while emission test gives an account of exhaust gases in combustion. For the burner thermal

efficiency was 66.27 %. Heat generated by burner was 1.7849 KW. In exhaust gas analysis,

volume of CO2 was found 0.9 % CO was found to be 50 ppm.

Mohd. Yunus Khan et al. [2] worked on improvement of thermal efficiency of LPG stove

indirectly to save fuel. They combine effects of porous media and insulation of combustion

chamber of stove to reduce heat losses by radiation. The conventional burner used for the

test had 68 % designed thermal efficiency, but actual efficiency was found to be 49 %. Two

different methods were implemented by authors to improve performance of a burner. One of

them was use of porous media and another was the use of insulation to combustion chamber

to reduce radiation losses. Porous media is readily used in commercial burners, it improves

rate of heat transfer and improves thermal efficiency. In order to create a porous medium,

authors fill the mixing chamber with ball bearings. In another case they insulate the bottom

base and side of mixing chamber. In both cases they perform the water boiling test as per

BIS guidelines separately and in another test they perform same test for combined effect

of insulation and porous media. In each case rise in thermal efficiency has been found out.

Porous media gives rise in efficiency by 10 %, while insulation alone gives 6 %. In third

case of combination, thermal efficiency was found to rise by 18 %. They innovates a very

simple, effective, safe and economical method to improve efficiency of a burner. In all the

three cases, heat energy wasted by heat radiations was reused.

Mohd. Yunus Khan et al. [3] in their next work aimed to find out most efficient burner


design. They conduct experimental work for different burner heads available and studied

their effect on performance of LPG stove. Burner heads were different in shapes and ma-

terial. Thermal efficiency of the burners was carried out by using water boiling test as per

BIS4246:2002. They carried out tests for 4 different burners as regular burner (CI), regular

burner (Brass), Flat face burner and Flower face burner. They use regular cast iron burner

as reference for comparing results. Designed value and observed value of thermal efficiency

of the burner are found to vary about 20 %. Experiments were repeated thrice for a burner

and their average as final result. Thermal efficiency of brass burner is found to be 4 % more

than that of with cast iron material. Flat faced burner gives 58 % and Flower faced burner

gives 50 % thermal efficiency.

N. K. Mishra et al. [4] worked on porous radiant burner (PRB) where the combustion

of fuel and air mixture takes place inside a matrix of cavities in porous medium. The con-

tributions of radiation and conduction in the PMC found significant due to high thermal

conductivity and high emissivity of porous matrix. They worked on medium scale cooking

range appliances using LPG as fuel. The porous medium used was SiC with 90 % poros-

ity. Investigation of thermal efficiency and emission levels of RRB at different heat inputs

were performed. Thermal efficiency for RRB obtained was about 50 % which is 25 % more

compared to conventional burners. Emission levels observed were also lower than those

of conventional stoves. Experimental work was performed on the commercial two layered

burner, two layers named as preheating zone and a combustion zone. Combustion zone was

made up of SiC porous matrix with high porosity (90 %), highly radiating, and the preheat-

ing zone with low porosity (40 %) ceramic matrix. The ceramic block was supported by using

a wire mesh. The burner casing was fabricated using alumina powder and sodium silicate

as binder. Water boiling test was conducted to evaluate thermal efficiency by Bureau of

Indian Standard (BIS):4246:2002. The emission characteristics of flue gases were also noted.

TESTO 350 XL portable flue gas analyzer was used to measure the CO and NOx. The

sampling was done as per suggestions given by the BIS: 4246:2002. Three different types of

burners available in the market were tested for both thermal efficiency and emission char-

acteristics. Their study was concluded with about 10 % rise in thermal efficiency in PRB

and at 10 KW load maximum improvement of 34.3 %. For the same burners, emissions of

combustion byproducts observed to be lower.

P. Muthukumar et al. [5] worked on porous radiant burners in LPG cooking stoves. They

designed and investigate performance of PRB (Porous Radiant Burner) in cooking stoves at

different equivalence ratios and power intensities. Also influence of ambient temperature


on performance of a burner was also studied. The flue gas analysis was also carried out.

Authors considered the basic heat transfer modes. In PRB heat is transferred by convec-

tion, porous medium then recirculates and preheats incoming air fuel mixture. Burnet was

fabricated with following structure, the combustion zone made by SiC porous matrix with

90 % porosity, preheating zone was filled with ceramic block having 40 % porosity. For this

burner thermal efficiency was estimated using the water boiling test using 5 Kg gas cylinder.

Rota meters were used separately for controlling fuel flow rate and air flow rate. The surface

temp at 5 different locations on matrix was recorded. CO and NOX emissions were also

measured. For this sampling is done as per guidelines given by BIS, IS 4246:2002.

They carried out experiments at constant ambient temperature, constant power per set

of experiments and observed effect of equivalence ratio () on thermal efficiency. Thermal ef-

ficiency and equivalence ratio of the fuel-air mixture were found to be inversely proportional

to each other. At higher equivalence ratio, heat loss is due to radiation. In their second part

of experiments, they studied the influence of ambient temperature on the thermal efficiency

by keeping equivalence ratio and power intensity constant. For this purpose they carried out

a series of experiments for several months and at different temperatures. Thermal efficiency

is found to be directly proportional to ambient temperature. In emission characteristics of

PRB, CO and NOX emission found to very low as compared to conventional burners. In

next part of experiment, authors tested temperature on porous burner surface at different

radial positions. Temperature difference was higher at lowest power input; it was due to

lower flow rates. A double layered PRB was used for the experimental work, with ceramic

blocks in preheating zone, and equivalence ratio range was 0.5-0.8.

V. K. Pantagni et al. [6] also worked for performance test of PRB for LPG domestic

cooking stoves. In their study the preheating zone of two layered PRB was made up of SiC

and Alumina balls. Authors focused on effect of equivalence ratios, burner diameter s, and

wattages on PRB performance used in domestic LPG stoves. The PRB had two layers, Com-

bustion zone made up of SiC and Preheating zone was made up of Alumina balls. The PRB

had 90 % porosity. They fabricated burner casing using alumina powder and sodium silicate

binder. The complete burner assembly was made up of combustion zone, preheating zone,

wire mesh, burner casing and mixing tube. Variations in burner design were obtained by

varying diameters and thickness of combustion zone. 5 different burners were manufactured

for experimental work.

In experimental work, PRBs were tested at different air-fuel ratios; by performing water


boiling test guidelines of BIS: 4246:2002 and thermal efficiency has been measured. The

TESTO 350XL flue gas analyzer was used to measure the CO and NOX emissions. K-type

thermocouples were used to measure the temperatures of burner at 4 axial and 7 radial

locations and their outputs were acquired through DAS to computer.

Locations of reaction zone and combustion zone had found to be important aspects for

uniform surface temperature. Temperature fluctuations are found to be more in preheating

zone and decreases at the interfaces. More fluctuations are found in preheating zone due to

presence of alumina balls, it decreased at the interface and at burner surface no fluctuations

are observed. Surface temperatures are noted at 7 locations for 5 different thermal loads.

Uniform temperature is observed at higher wattages, while at lower wattage a temperature

difference is noted.

In thermal efficiency test, burners were tested at different equivalence ratio for differ-

ent wattages. For all burners maximum efficiency is observed at different equivalence ratio.

Equivalence ration and thermal efficiency are found to be inversely proportional to each

other at constant wattage. In emission characteristics, PRB gives low values of CO and

NOx emissions compared to values prescribed by World Health Organization (WHO). At

given wattage increased value of CO emission is found with equivalence ratio.

Apinunt Namkhat et al. [7] in their work on ”The Effect of Primary Air Preheat on the

Primary Aeration of a Self- aspirating Burner”, Combustion and Engine Research Laboratory

(CERL), Department of Mechanical Engineering, Faculty of Engineering, King Mongkut’s

University of Technology Thonburi (KMUTT), Bangkok, Thailand., investigate the effects of

changes in the combustion air temperature on primary aeration and flame structures. Their

studies were performed for both with and without preheat case of combustion air.

Self-aspirating burner with LPG as fuel was used to perform the tests. They observed

clearly that the primary aeration in both cases rapidly increases at the early stage with an

increasing heat input. After that, the primary aeration remains stable and independent on

the heat input. The primary aeration decreases with an increasing preheated air tempera-

ture. Static pressure also varies along the mixing tube for the without preheat case. It has

been observed that the vacuum magnitudes decreased with decreasing heat input, due to

low primary aeration. The flame image of a self-aspirating burner was also studied. They

found that the increase of thermal input leads to the increase of flame height, because of the

high velocity of the gas mixture.


Sumrerng Jugjai et al.[8] proposed a new design concept of burner to improve thermal

efficiency of conventional flame burner for domestic appliances with porous medium. Porous

Radiant Recirculating Burner (PRRB) was the innovation to recycle the heat of exit thermal

enthalpy of flames of burner to premixed mixture. A few changes were made in conventional

burner for providing a vent as provision for heat feedback mechanism from product to reac-

tant gases. Their work was concluding with significant improvement in thermal efficiency,

better combustion stability and emission characteristics compared to conventional burner.

Jose M. N. Rodrigues et al. [9] worked on stability analysis and flow characterization

of Multi-perforated plate premixed burners. Authors studied the flame stabilization for

methane and propane on different burner plates configurations. Increased distance between

holes on the hole pattern of the perforated plate degrades stabilization where as diameter of

holes and number of holes are not much relevant. PIV Measurements and Direct visualiza-

tion of the flow suggests that flame stabilization is affected by entrainment of cold air, and

chemical reaction rates. As gap between holes increases, more cold air get entrained giving

rise to less stable flame. They focused the work on blow off type burners, especially flow

velocity distribution on flame stabilization. A set of steel burning plates was analyzed for

stability investigation for three geometrical parameters and for 2 fuels. Three parameters

were hole diameter, number of holes and distance between holes, and fuels were methane

and propane. The flow characterization using visualization methods and PIV measurements,

focusing on the particular stability mechanisms is followed by stability limits of each burner

plate.

The combustor was made up of an aluminum mixing chamber, mixing and supplying the

air fuel mixture developed until it reaches the top exit. At top the burner plate distributes

reacting mixture in several jets for combustion. Different burners with different geometric

configurations and for different fuels were analyzed. Dantec 2D-PIV system was used for the

velocity measurements of the flow just downstream of the burner-plate. They plotted blow

off points in stability diagram for each burner and get diversion of blow off limit with no of

plates. They built a nonlinear model with equations forms to fit according to size of ports,

distance between ports and no of ports. From the results, the parameter of distance between

holes found a major effect on the model the other two, and became a stronger parameter

affecting the flame stability limit of the burners. The blow-off limit increases slightly at the

low power, but remains almost constant as the flow velocity is increased.


In next part of study, characterization of the reacting and isothermal flow with different

plates has been covered. Several measuring and visualization methods were used to analyze

the isothermal and the reacting flow around the burner. By tracking the position of small

seed particles injected in the flow, it was possible to observe the flow paths and picture an

overview of its structure as it crosses the flame front. The post-processing of the position

of the particles was achieved by a PIV algorithm and actual velocity field of the reacting

flows resulting from each burner plate and actual velocity field of the reacting flows resulting

from each burner plate was achieved. Direct photography technique was used to represent

resulting propane flame for different operating conditions on the plates.

Walter M. Berry et al [10] efficiently worked for the burner designs for improved effi-

ciency for better utilization of gas. Their work was based on several thousand observations

in order to study the effects of large number of variables affecting performance of a burner

at different operating conditions. Their results of investigations on the effect of design of

injecting tube and orifice on rate of consumption of burners are given. While doing so they

consider many depending parameters like relations between port area and rate of consump-

tion of burners, limit of velocity of efflux from the ports. Another important part of this

area including flame characteristics with different gases , efficiency of operation of burners

of various designs, completeness of combustion etc were not studied in their work. Based

on their large no of investigations, improved methods for studying burner operations were

developed. An apparatus developed by them can determine the volume of air injected for

any burner, under any condition accurately and quickly. For any burner, the limits of op-

eration can be determined with any gas quality. The principles governing air injection, the

injecting tube, the burner and burner ports, theory of flow of gas through different types of

orifices, the air shutter and the burner and burner ports are some parameters to investigate

the burner.

H. S. Couto et al. [11] in their work described the design procedure for domestic gas

cooking devices. The major criterion for burners design were flame stability, flash back

effect, flame lifting mechanism, as per Brazilian Society of Technical Norms. Authors ex-

plain design procedure with mathematical equations. They also provide stability diagrams

for natural gas and manufactured gas for making optimum burner selection on the basis of

flame stability with different criterion. The relation between hole diameter, no of holes and

power requirement gives starting of design process. For various fuels data is provided for

flammability limits, quenching distance and minimum energy required for ignition. Flame

size limits verification for different hole shapes can be performed. Design reliability can


also be checked by using chart provided for maximum CO emission in combustion products.

Along with burner, premixing pipe design is also covered by authors. They concluded their

work that flame aerodynamics is the most important parameter in burner design.

John H. Eiseman et al. [12] discussed the general conditions of satisfactory operation of

gas burner. Authors gave years for their experimental work. Limits of flame flashback and

for incomplete combustion were determined along with several design details for a typical

burner. They developed the laboratory apparatus for proposed work. The most favorable

combination of conditions was developed and effects of heat transferred on changes in effi-

ciency and rapidity were developed. Designs were provided with allowances for variations

in pressure and inaccuracy. The procedure of burner design for particular fuel gas was de-

scribed and the best design can be decided by considering efficiency of heating, safety and

the time required for the operation. The work concentrates on general design of a burner

based on the parameters affecting its performance. Flash Back, Blow off and yellow tipping

were the basic criterion to decide the satisfactory burner design. Using the apparatus, going

through so many trials, the data was presented graphically. Many variations for number

of parameters were obtained these parameters were port size, distance between burner and

utensil, heating time were prime parameters, for design.

Walter B. Kirk et al. [14] discussed some fundamentals concepts related with burner

design. The relationship developed using basic critical velocity gradient theory with flame

stability. Some burner design factors considered by them were port size, depth, and spac-

ing; port loading, primary aeration and gas composition. Lifting characteristics of flames

were considered for study using critical boundary velocity gradient theory. Effect of differ-

ent burner parameters like burning velocities, port dimensions, port sizes etc on the burner

performance in terms of with flash back, flame lift and yellow tipping are explained. They

observed within a span o loading, lifting limit curves for various gases were parallel.

Channing W. Wilson et al. [15] determine performance coefficient of a gas burner by

an indirect procedure. The method consists of prediction of limits of satisfactory perfor-

mance of a gas burner were combined with flame stability diagram for the fuel gas. Their

work concludes that the performance coefficient represents the influence of burner design

and construction alone on its performance and not reflects the properties of the fuel. Ex-

periments were conducted for 4different burners with more than one fuel gas. Burners were

different in geometrical properties, where as fuel gases were used for test with each burner.

Flash back limit and blow off limit were determined with different fuels mixtures prepared


in laboratory. A sound basis has been provided for further study of burner design parameters.

David Fulford et al. [16] had explained the basic design procedure for bio gas burner.

In the course material, every parameter of burner design elaborated very precisely. Various

possible designs of venture, ports, throats, possibilities of number of arrangements and the

precise way of selection of the perfect among these has been presented keenly. Requirement

and attainment of primary and secondary air also explained.

J.B. Singh et al. [17] in ”Experimental Investigation and Mathematical Modeling to

Study the Premixed Laminar Flame Propagation”, Defense Science Journal, Vol. 57, No. 5,

developed a test rig which can be used for different gaseous fuels with varying geometries of

burners. They perform experiments on a newly designed flame propagation test unit using

burners of different geometries. Burners used for test was premixed and was non-stationary

flame type. Tests were performed at different air-fuel ratios and with burners having different

Length to Diameter ratio. They calculated the flame speed. The flame stability zones un-

der different conditions have been studied using design plots from experimental data. They

derived a generalized mathematical equation for optimization of the flow and geometrical

condition in laminar flame propagation.

Catharine Tierney, et al. [18] worked for ultra lean methane combustion in porous

medium with a flame less type. Convective and Radiltaive transfer models were considered

which are not considered by previous authors. The combined use of CFD and a relatively

detailed skeletal chemistry was the attractive feature of this study. The minerals and pro-

cess industries were the target application for improvements. ANSYS CFX 12.0 was used

as CFD tool with Navier-Stokes equations; chemical species transport equations solid and

fluid energy equations. Also energy equations were implemented to model heat transfer.

A numerical model for materials design in ultra lean combustion design was the goal for

the work. Numerical model using CHEMKIN was done and the results were validated with

analytical validation of the heat transfer equations using fixed flux conditions. Chemical

mechanism in the numerical model was validated using CHEMKIN and this was achieved

by imposing a CFD fluid temperature output profile onto a plug flow reactor in CHEMKIN

with same inlet conditions.

Musthafa Abdul Mujeebu et al. [19] worked on development, numerical simulation and

characterization of compact premixed LPG burner based on surface combustion in porous

inert medium. Porous medium was made porous with two layers named preheating and


reaction zones, containing Alumina (Al2O3) foams with 26 ppcm and 8 ppcm respectively.

The flame stability, temperature distribution within the combustor, maximum flame tem-

perature, NO, CO and SO2 emissions and thermal efficiency were measured and compared

with those of conventional LPG stove. About 80 % fuel saving and 75 % reduced NOx

has been obtained with the advanced burner along with reduced emission of CO and SO2.

Computational methods were used in order to evaluate effect of porosity and thickness of

reaction layer, using a two dimensional simulation.

Obada David Olubiyi et al. [20] has designed fabricated and evaluate the portable biogas.

The performance of burner was evaluated using water boiling test, and basic design princi-

ples of flame stability were used to design the burner. For his thesis work he started designed

procedure very starting form biogas generation process. The complete stove assembly was

designed and manufactured by him. Invention was initiated to design an eco friendly and

environment friendly gas stove with biogas. The burner top along with throat, mixing tube

were designed and fabricated to give off a continuous blue flame. The flue gas analysis was

also performed; and observed less emission levels.

Shuhn-Shyurng Hou et al. [27] also worked for the energy efficient and low emission gas

burners. The major parameters to study were swirl angle and inclination angle of burner

and their effects on swirl flow. They proposed new designs with adjusting the two values

and compare these results with conventional burner. Prime factor for gas burner design was

the port design. Variations in swirl angles and inclination of outer ring were changed by

keeping changing other parameters. The effects of adding a shield enclosing the burner on

thermal efficiency and CO emission were also studied by using a circular shield of stainless

steel sheet. A higher efficiency was found to be gained by individual modifications.

2.1 Objectives of the Project

Form the above literature review it is found that for domestic range of LPG stove cooking

burners, thermal efficiency is the prime parameter for deciding its performance. Many re-

searchers have worked for thermal efficiency and emission characteristics of a burner, using

PMC (Porous Medium Combustion) for various gaseous fuels. A considerable work has been

done for Methane and Natural gas combustion burners. In case of domestic LPG stoves,

efficiency is evaluated and efforts are done to improve it by addition of PMC. Comparatively

less work is done in the area of design of a LPG stove burner.


Thermal efficiency completely depends on the material and design of a burner rather than

the fuel to be used. In burner design, various parameters like number of ports, size of ports,

quenching distance of ports has great influence. Flame stability criterion is the key param-

eter for any burner, as it decides acceptance limit for design selection. Proper selection of

these parameters is necessary to obtain a satisfactory design of a burner.

Maximum thermal efficiency of a LPG stove is in the range 65-68 %. However, there is need

for improved burner design in order to achieve better utilization of fuel indirectly utilization

of economy. Even 1 % rise in efficiency is attained for a single burner; it will contribute a lot

when integrated to a large scale for widely covered network of the most popular domestic

fuel. Therefore objective of present work is to analyze the burner design for domestic pur-

pose.

It is also decided to evaluate thermal efficiency of the domestic burner currently used, to

study effect of port area on it and to study the effect of ambient temperature and warm (pre-

heated) burner on its performance. Based on the experimental results the flow is analyzed

using computational methods.


Chapter 3

Design Analysis of Burner

Design of any burner is said to be best if it can give maximum utilization of a fuel. For

any burner design its very complex problem to design it to give satisfactory performance. In

case of stoves their performance is based on two factors, burner design and the combustion

of fuel i.e. LPG. Basic intension for this work is to study design procedure for a burner and

modify it in order to obtain improved efficiency.

In LPG stove thermal efficiency is considered as a coefficient to evaluate its performance.

All the stoves are labeled with certain thermal efficiency when manufactured. According to

BIS star rating the stoves are rated as per their thermal efficiency. The Star rating levels for

Domestic LPG Stoves is as given below-

Star rating of burners as per guidelines provides by BIS:

Table 3.1: Star rating of stoves to be labeled [22]

Star RatingThermal Efficiency

(As per IS 4246:latest)

1 Star If Thermal efficiency ≥ 68 % and < 72%

2 Star If Thermal efficiency ≥ 72% and < 75%



5 Star If Thermal efficiency ≥ 81%

It is required to attain minimum 68 % thermal efficiency to get a star label as per BIS.

Number of stars on the label reflects its better heat utilization. The stove efficiency is di-

rectly given from efficiency of the burner rather than the fuel is being used. Hence in order

to obtain a better performance of a stove, burners are the prime element to be considered


to modify.

When air-fuel mixture passes through the burner, the momentum flux of air is several

times greater than flux of fuel. Some fraction of total air is mixed with the fuel at entrainment

of fuel in mixing chamber; this air is known as primary air. Rest amount of air, known as

secondary air is supplied in the burner through an opening from its bottom. After combustion

started, mixing and combustion take place simultaneously. Free jet phenomenon takes place

at downstream in a burner as mixture of air and gaseous fuel passes through it. For complete

and efficient combustion, mixing of secondary air in the jet is important. If this does not

happen, it may give rise to formation of soot.

Figure 3.1: Mixing of air-fuel in a burner [31]

3.1 Fuel Jet

As a fluid is discharged through the nozzle a jet is produced. Velocity of the fluid is acceler-

ated in the jet. The characteristic feature of the jet is that it spreads due to the difference

in the density of the surrounding and the jet. A cold jet in hot surrounding spreads slower

than a hot jet in cold surrounding in the same surrounding. Jet spreading takes place due to

entrainment of the surrounding. . For any downstream axial distance, the velocity is maxi-

mum at the centre and minimum at the periphery such that a parabolic profile is developed

-


Figure 3.2: Spreading of an axis-symmetric jet in the surrounding[31]

In addition, jet carries with it momentum flux, which is given by the relation,

momentum flux = Mass of jet X velocity of jet

Mass of jet = Mass of air at exit of nozzle + Mass of surrounding

Mass of air at the exit is constant; but entrainment of the surrounding in the jet increases

the mass of the jet and decreases the velocity of the jet. Entrainment of the surrounding

depends on the difference in the momentum flux within the jet and that of surrounding.

And it will be continued till the difference in the momentum flux exists.

3.2 Behavior of free (unconfined) and confined jet

A free jet has no confinement and hence can spread till the difference between the surrounding

and the momentum flux of the jet becomes zero. Figure 3.3 shows the entrainment in the

free jet

Figure 3.3: Entrainment of products of combustion in the jet. [31]

In case of free jet, at the point secondary air is entrained. Beyond point A the products

of combustion entrain due to the excess momentum in the jet.


3.3 Importance of primary and secondary air in Burner

Design

In the design of burner for gaseous fuel it is important to design the primary air as per the

requirement. The amount of air is much greater than that of fuel; momentum flux within

the jet is controlled by the primary air. The primary air controls the air fuel mixing rate and

assists in stabilization of the jet and to control the recirculation. Secondary air is introduced

through an opening from bottom of burner top. When the secondary air is mixed completely

with the fuel, re-circulation in any burner sets.

3.4 Different Parts of a Burner System

In Domestic LPG stove, the burner is composed of assembly of injector, mixing tube and

burner top. Design considerations for each of these parts are discussed in this chapter.

Generally all gas burners used for domestic gas appliance are of Blue flame type or Bunsen

type also commonly known as atmospheric burners. A very prime requisite of any burner is

that it should be capable of burning the fuel completely. While designing burner for stoves,

laminar flow of gas through mixing tube is assumed. Performance of burner is decided on

quality of flame and its appearance.

3.5 Injector Orifice

An injector or orifice is a device made up of brass with micro drilled, screwed to the end of

gas line fitting with a provision for easy replacement. Its function is to control the gas flow

rate and separate burner from the gas supply. The flame could not enter the gas supply line

due to injector. When regulator valve is turned on gas from inlet pressure comes to injector

and when knob is switched on, gas gets injected into throat of mixing tube. Injector controls

the amount of a gas used by a burner. It is made up of brass thimble. It can separate burner

from gas supply pipe. The gas flow rate through the gas pipe is given as:

Q = V ∗ A (3.1)

Where , Q= Gas flow rate( m3h−1)

V= Gas flow velocity

A= Area of pipe through which gas flows.


3.6 Gas flow through an injector orifice

Gas flow through an injector orifice using empirical version of Bernoulli’s theorem is given

as

Q = 0.0467CdAo

√S

P(3.2)

Where, Q= Gas flow rate( m3h−1)

Ao = Area of orifice (mm2)

P= Gas pressure before orifice (mbar)

S= Specific gravity of gas

=coefficient of discharge for orifice =0.8 to 0.95.

3.7 Combustion

It is a process in which release of potential energy of fuel by combustion with air requires

several stages, namely-

• Mixing of air and fuel

• Ignition of the mixture

• Chemical reaction

• Disposal of products of combustion from the reaction site so that fresh reactants are

available.

Accordingly mixing is the slowest step in the process of combustion. Total efficiency is

defined as the effectiveness of any combustion apparatus to convert the internal energy con-

tained in the fuel into heat energy for use by the process. Complete combustion occurs when

all of the energy in the fuel being burned is extracted and leaves no Carbon and Hydrogen

compounds are left unburned [32]. Combustion efficiency is the difference of total energy

contained per unit of fuel and the energy carried away by the flue gas and unburned fuel.

Any heat losses within combustion lower the efficiency of the process. Fuel, oxygen, and heat

are the three essential components of combustion. Stochiometric combustion is defined as

ratio having just the right amount of oxygen and fuel mixture so the most heat is released.

In fossil fuels, the chemical elements that react with oxygen to release heat are carbon and

hydrogen. Generally all common fuels consist of compounds containing certain amounts of

hydrogen and carbon, which are commonly called hydrocarbons.


Any fuel is graded according to its combustion process. And for a good combustion, it is

necessary that it should be capable to release all of the heat in the fuel.

A complete combustion can be accomplished by controlling following three parameters -

1. High enough temperature to ignite and maintain ignition of the fuel,

2. Intimate mixing or Turbulence of the fuel and oxygen.

3. Sufficient time for complete combustion.

Heat will be carried away by exhaust while firing hydrocarbons in the form of water vapor

as by-product of burning hydrogen. Also amount of fuel with the available combustion air

may potentially result in unburned fuel and carbon monoxide generation. A very specific

amount of O2 is required for perfect combustion; some additional (excess) air is required

to ensure complete combustion. If too much air is supplied, it will results in loss heat and

efficiency.

The quality of combustion is decided by its byproducts and amount of heat, shown in figure

below-

Figure 3.4: Combustion Process

Liquefied petroleum gas (LPG) is an extract form crude oils consists of propane, propy-

lene, butane, and butylenes; the product used for domestic heating is composed primarily of

propane.

LPG is considered a ”clean” fuel because as it does not produce any visible emissions. How-

ever, gaseous pollutants such as nitrogen oxides (NOx), carbon monoxide (CO), and organic

compounds are produced as are small amounts of sulfur dioxide (SO2). The most significant

factors affecting NOx, CO, and organic emissions are burner adjustment, burner design,

apparatus operating parameters, and flue gas venting. Improper design, blocking and clog-

ging of the flue vent, and insufficient combustion air supply results in improper combustion

and the emission CO, hydrocarbons, and other organics. NOx emissions are a function of


a several number of variables, including temperature, excess air, fuel and air mixing, and

residence time in the combustion zone. The amount of SO2 emitted is directly proportional

to the amount of sulfur in the fuel. For household LPG stove burning, SO2 formation is

much low as it can be considered as negligible. During the combustion process, nearly all

of the fuel carbon in LPG is converted to CO2. This conversion is relatively independent of

firing configuration, although the formation of CO acts to reduce CO2 emissions; the amount

of CO produced is insignificant compared to the amount of CO2 produced. The majority

of the 0.5 percent of fuel carbon not converted to CO2 is due to incomplete combustion in

the fuel stream. Formation of N2o is dependent upon many factors. During the combustion

process is N2o formation is governed by a complex series of reactions and it is minimized

when combustion temperatures are kept high.

Stoichiometric Combustion - Stoichiometric combustion is the theoretical point at which

the fuel to air ratio is ideal so that there is complete combustion.

Fuel - Air Ratio - The fuel-air ratio is the proportion of fuel to air during the combustion.

The optimal ratio (the stoichiometric ratio) occurs when all of the fuel and all of the oxygen

in the mixing chamber balance each other perfectly. The ration is said to be rich burning is

when there is more fuel than air in the combustion chamber while it is lean burning occurs

when there is more air than fuel in the combustion chamber. Theoretical Stoichiometric

Combustion for complete oxidation of a fuel with no excess air for LPG (Mixture of Propane

and Butane). In combustion of Propane (C3H8) and Butane (C4H10), assuming complete

combustion, the stiochiometric air required is calculated by chemical reactions of combustion

and is given below-

C3H8 + 5O2 + 18.8N2 −→ 3CO2 + 4H2O + 18.8N2

C4H10 + 6.5O2 + 24.5N2 −→ 4CO2 + 5H2O + 24.5N2

Stoichiometric Air Requirement on the basis of 1 volume of the fuel gas, the propane

content requires 0.6 (5 + 18.8) = 14.28 volumes air

and the butane requires 0.4 (6.5 + 24.5) = 12.4 volumes air

Hence the stoichiometric air-to-fuel ratio is 26.68:1

Normally burners are run slightly lean with small excess air. It is an air premixed type

burner, where air and fuel are mixed in a tube before it burn. After burning to flame, post


aeration of flame takes place. The air from atmosphere is supplied at the flame surround-

ing at end of gas line. The amount of primary air supply depends on burner design. And

primary aeration decides the quality of combustion. Hence location and size of primary air

port is much important.

3.8 Air Entrainment in the burner system

Throat is region in mixing tube where gas emerging from injector enters the end of mixing

tube. It has larger diameter than that of an orifice, hence the velocity of gas stream get

reduced to a lower value. The velocity of gas Vo in injector orifice is given by- The gas

emerging from the injector enters the end of the mixing tube in a region, the ”throat”. The

throat has a much larger diameter than the injector, so the velocity of the gas stream is

much reduced. The velocity (Vo) of the gas in the injector orifice is given by:

VO =Q

3.6 ∗ 10−3A0

∗MS−1 (3.3)

Where, Q in m3h−1 and A0 in mm2.

while the velocity in the throat is reduced to:

Vt = VoAo

At

= Vo(do)

2

(dt)2(3.4)

Also the gas pressure just after nozzle becomes-

pt = po − ρ(Vo)

2

2g[1− [

dodt

4

]] (3.5)

The value of po is atmospheric pressure, as throat is open to air, giving a sufficient

pressure drop to draw in the primary air through the inlet port in order to mix with fuel gas

in the mixing tube.

po is atmospheric pressure, as throat is opened to atmosphere. Primary aeration is depend

on entrainment ratio (r), given by Prigg’s formula.

r =√S = (

√At

Ao

− 1) =√S(dtdo− 1) (3.6)

Where At and dt are the area and diameter of throat and Ao and dt are the area and

diameter of injector orifice. Prigg’s formula is applicable if Ap lies between 1.5 to 2.2 times.

The primary air is much enough to provide stochiometric air fuel ratio.


3.9 Throat size

The flow rate of mixture in the throat Qm is given by

Qm =Q(1 + r)

3600(3.7)

With Qm in m3/s and Q is in m3/h.

The pressure drop in mixing tube must be known, hence calculating of the Reynolds

number is necessary. The Reynolds number is given by-

Re = ρdtvtµ

=4ρQm

Πµdt(3.8)

where ρ and µ are the density and viscosity for the mixture respectively. The pressure

drop ∆p is given by,

∆p =f

2ρ

16

Π2

(Qm)2

(dt)5Lm =

f

2ρ

16(Qm)2

Π2(dt)5Lm (3.9)

Where,

f = 64/RewhenRe < 2000, and

f = 0.316/Re1/4whenRe > 2000.

The pressure drop calculated should be much less than driving pressure of fuel. Normally

burners are designed for greater than optimum aeration throat size. There is an arrangement

for restricting the air flow as per requirement.

3.10 Mixing Tube

Injector injects gas to atmospheric pressure from high inlet pressure in throat of mixing

tube; this pressure drop creates suction of primary air through air inlet ports. In design

point of view, throat diameter and length of mixing tube for necessary pressure drop are

important in mixing tube are necessary. Mixing tube material is Aluminum. Its dimensions

are derived from the throat diameter. Length of mixing tube is given by an empirical formula-

Lm = 10Xdt.


Figure 3.5: Mixing tube and Burner Assembly

3.11 Burner Top

Its designs are varying as per the shape of combustion chamber and incase of cooking stoves,

size and shape of utensil is decides the shape and size of a burner. for example pipe burner

are used for rectangular heating plate. Common shapes of burner ports are rectangular,

square, and circular or in special cases these could be in the form of slots too. Depending on

shape of a port, its size can be calculated. Here are some conditions which decide the shape

of a burner to be select.

3.12 Burner Ports

Burner is the prime part of an apparatus, as it is the part supplying heat to the application.

Major function of a burner is to direct heat to the application. Designs of burners can vary

as per the requirement of application.

Table 3.2: Theoretical and empirical correlations to estimate the vertical length of laminarflames[11]

Burner Geometry Conditions

Circle Momentum or Buoyancy Controlled

Square Momentum or Buoyancy Controlled

Slot Momentum controlled Buoyancy controlledMixed momentum-buoyancy Controlled


3.13 Burner port design

The burner port area is limited by flame stabilization theories. The size and position of

individual ports on a burner can define by various factors as spacing between the ports, heat

pattern required etc. As most of cooking utensils has circular base, burner ports of domestic

cooking stoves are arranged in circular pattern. Size of circle depends on average size of

utensils.

3.14 Flames

Appearance of a flame in any combustion plays a vital role, as it directly indicates the quality

of combustion. Flame velocity, flame height, its color directly indicates amount of fuel in air

fuel ratio. While some phenomenon like flame blow off, flame lift and sound during burning

decides quality of a burner. Ultimately quality of combustion depends on fuel intake and

burner.

As gas reaches to mixing chamber with low pressure and high velocity, atmospheric air

get sucked into tube with the gas through primary air ports, air and fuel mixture reaches to

its stiochiometric proportion burn when charged. The continuous flame of gas can remain

stable due to secondary aeration. The unburned gases heated up in an inner cone and

starts burning as a flame when ignited. The flame burns with inner cone shape; this cone

shape is a result of laminar flow in mixing tube. Size of inner cone is affected by primary

aeration. Smaller, concentrated and high temperature the flame indicates higher proportion

of primary air and vice versa. Hence primary as well as secondary air are important for a

complete combustion. The flame remains steady due to the supply of secondary air from

both sides of burner i.e. inner and outer. The shape of flame is combination of both parabolic

curves due to air.


Figure 3.6: Typical flame of a gas burner

There are three theories for burner port design based on flame stabilization namely- Blow

off (Flash back), lifting of flame and Yellow tipping. Quality of Combustion of any burner is

reflected by quality of flames. Stable, clean, blue and soundless flames are ideal. The flame

characteristic diagram for given gas is fixed, and it decides the limiting values for burner

design. There are different well-defined areas of operation for a burner that operates on

gaseous fuels. The three regimes may be distinguished as follows -

1. Yellow tipping- It is the direct representation of incomplete combustion. When

the airflow to burner is prevented, the flame will have a yellow tip and may produce

smoke. When the airflow is increased, yellow tip disappears and is replaced by a blue

non-luminous flame. Every fuel gas requires a certain amount of air to completely

eliminate yellow tips from appearing in its flames. This might be either in the form

of primary air or secondary air diffusing to the point where yellow tips appear in the

flames.

LPG burning is complete and clean, hence the problem of yellow tipping is rare in this

case. But sometimes if burner ports get blocked, they will restrict the mixture flow

out of port and may give rise to yellow tipping. Port size, spacing, and the number

of rows of ports affect the degree to which secondary air can be utilized in order to

eliminate yellow tipping.


2. Flame Lift off If the airflow to burner is gradually increased with a constant gas

flow, and if sufficient gas flow exists, the yellow tipping will disappear giving a blue

flame. Further increase in airflow will result in the lifting of the flame around the

surface of the burner port. At this moment, the velocity of mixture leaving the burner

approaches the mixture flame speed. If airflow is further increased, the flow velocity

will exceed the flame speed and the flame will lift off and be extinguished.

Figure 3.7: Flame lift off

Lifting tendencies can be reduced by use of larger, closely spaced ports and deeper

ports.

3. Flame flash back:- The back flow of flame at a burner port in the mixing tube is

commonly known as lighting back. As flames are dependent on the relative velocities

of air-gas mixture flowing out of the port and the counter propagation of flame into the

air-gas mixture in the ports and burner head. For a normal flame, there is equilibrium

between these factors takes place a short distance above burner port.


Figure 3.8: Flame flash back

To achieve a desired balance in burner design, knowledge of quantitative effects of all vari-

ables is necessary. [Applying] Port area for any application is dictated by limiting conditions

which produce the critical flame characteristics listed above. A typical flame characteristic

diagram describes limiting conditions in terms of primary aeration and port loading per unit

time per unit port area. Port size, depth or port spacing is the variables displace the limiting

curves in fact displace the area of stable and blue flame.

Figure 3.9: Stability Diagram for Manufactured Gas Flames, displaying flashback, liftoff and

yellow tipping

The stability diagrams are used as a reference to select the port area which can give the

burner designs with optimum use of fuel and better combustion. The specifications should

be selected in such a way that it will cover a wider area in above diagram. If primary air

entrainment increases, it will results in lean mixture. It will give rise to lifting flames, where


if it decreases, will result in blow off flames.

The mixture supply velocity, vp is

vp =Qm

Ap

� stiochiometricflamevelocity (3.10)

Where Qm = mass flow rate of fuel in m3/s and Ap is total port area in m2 and given by

Ap = n ∗ Πd2p4

(3.11)

Where n is the number of ports and dp is diameter in m.

3.14.1 Burner Manifold (Combustion chamber)

It is requirement of a burner that it’s each port should be of same size in order to maintain

uniform air fuel mixture flow. Also pressure drop should also be of same value. Cross section

al area of this combustion chamber should be much larger than the total port area. Outline

of a complete manifold is given below.

Figure 3.10: General combustion chamber structure of LPG stove burner.

Burners are designed in such a way that gives aeration greater than optimum.

Length of mixing tube is ten times of throat diameter, to allow good mixing of gas and air.

3.14.2 Burner Top

The air fuel mixture from combustion chamber penetrates through burner ports and burns

with a continuous flame when ignited. Shape and size of a burner top is basically decided

by combustion chamber shape and size. Generally all domestic cooking stoves in India have

circular burner tops with ports arranged in circular manner with no. of ports at different

pitch circle diameter. It is so designed that heat can be directed to where needed in appli-

cation.


Secondary airbasically helps for further combustion of flame and ensures complete com-

bustion. In order to assure an ample amount of secondary air, ports should be so arranged

that they should readily allow secondary air. Instead of continuous rows of ports, alternate

positions should be preferred.

Flame stabilization can be achieved by number of ways to avoid flame lift from burner

port. Major criterion for burner ports position should be maximum secondary air supply for

a better stable flame. Various port arrangements are possible in a burner as per the space

availability. While deciding the perfect arrangement, consideration of proper air supply to

the burner should be considered. Following are some possible arrangement of burner ports.

Figure 3.11: Possible flame arrangements

Normally burners are manufactured by using angled burner arrangement as this arrange-

ment assists the secondary air to support and its give a flame directing toward outer periphery

of a utensil on a burner. All such flames from all ports will collectively concentrate to utensil.

3.15 Design Calculations for conventional burner

Following the procedure explained this chapter; a burner can be designed for required power

output. Once total port area is calculated, a number of possible combinations are possible

for burner ports size and number of ports. In current case, the burner is designed for 2.81Kw

power, this is the power output evaluated from the mass flow rate of fuel when it flows from

the cylinder to orifice. Required data for calculations-

S= specific gravity of fuel

Cd = coefficient of discharge for orifice

r = entrainment ratio = stiochiometric ratio /2.

p= minimum gas supply pressure= 30Kg/cm2 = 2.942KN/m2


The gas flow through injector orifice, Q from equation no. 2 is given by-

Q = 0.0467CdAo

√s

p(3.12)

Substituting

Ao = Πd2o4,

and Cd = Coefficient of discharge for orifice, Cd =0.9,

s= specific gravity of LPG, 1.75 and

P = gas pressure before orifice = 29.412

Q = 0.036Cdd2o

√s

p(3.13)

As mass flow rate of LPG through orifice is 0.5 m3h−1

0.5 = 0.036 ∗ 0.9 ∗ d2o

√1.75

29.412(3.14)

Hence do = 1.8886 mm

Where do= Orifice diameter in mm. And area of orifice is - Ao =2.8 mm2

The velocity of gas in injector orifice from equation (1) is given by,

VO =Q

3.6 ∗ 10−3A0

∗MS−1 (3.15)

Substituting values of Q and Ao,

V0 = 49.60ms−1

Throat dimensions are derived from the injector orifice dimensions, with entrainment ratio.

It can be determined by area of throat and the injector given in equation 3.

Where r is the entrainment ratio, for LPG is 14,

dt = (r√s

+ 1)d0 (3.16)

dt = 21.89mm

For standard size of tube, its value is rounded to 22mm. Hence dt= 22 mm.

Area of throat can be calculated as At = 379.94 mm2 = 380 mm2.

With previous meanings of Q and Ao, while velocity of air fuel mixture in the throat is

Vt = VoAo

At

= Vo(do)

2

(dt)2(3.17)


On substituting values of velocity at orifice, orifice diameter and throat diameter,

V t = 0.3645m/s

Also gas pressure becomes,

pt = po − ρ(Vo)

2

2g[1− [

dodt

4

]] (3.18)

Where ρ = Gas density

pt = 105 − 2.011(49.60)2

2 ∗ 9.81[1− [

1.8666

22

4

]] (3.19)

pt = 105 − 252.147

pt = 99.75 ∗ 103Pa

This is gas pressure at throat at atmospheric conditions.

At throat the air from primary air port and high velocity fuel get mixed to stoichiometric

proportion and move towards combustion chamber. In combustion chamber, the mixture

dispersed with most probably with laminar velocity. When ignited, the mixture starts burn-

ing with a continuous flame. The flame propagates separately from each port; the continuous

flame is jumping of all such flames from port to port. The flow rate of mixture in throat

(Qm) is given by

Qm =Q(1 + r)

3600(3.20)

With Qm in m3/s and Q is in m3/h.

Qm = 2.08 ∗ 10−3m3/s.

In order to calculate pressure drop due to flow of mixture in mixing tube, Reynolds number

calculation is necessary. From equation 4.22, For a variety of port geometries over a broad

range fluid velocities expressed by The Reynolds’s number Re. It can be found out by either

theoretically or from pressure drop measurement. By using an indirect method of critical

flow rate of a gas, parameter f can be evaluated by using its flame stability diagrams. Re

can be calculated -

Re = ρdtvtµ

=4ρQm

Πµdt(3.21)

Substituting values of density and coefficient of friction, mass flow rate, throat diameter

in above equation, Re = 2201.86.


The parameter f, represents the influence of the burner port g geometry, has been found

to have the form

f =a

Rbe

(3.22)

In current burner case, pressure drop in mixing tube can be calculated based on Reynold’s

number, and 33

As for current condition, Re >2000, parameter f now can be -

f =a

R1/4e

= 0.0461 (3.23)

The pressure drop in mixing tube is given by

∆p =f

2ρ

16

Π2

(Qm)2

(dt)5Lm =

f

2ρ

16(Qm)2

Π2(dt)5Lm (3.24)

Pressure drop can be calculated by

∆p =0.0461

22.011

16

Π2

(2.08 ∗ 10−3)2

(0.022)50.22 (3.25)

∆p = 13.895Pa

Pressure drop in mixing tube is much less than the driving pressure in throat, (252.147Pa)

from equation (5).

As pressure drop is satisfactory, burner port area can now be selected. Mixture flow rate

and Stoichiometric flame speed of gas gives port area of burner as given below-

The air fuel mixture supply velocity is given by;

Pressure drop can be calculated by

vp =Qm

Ap

(3.26)

Where Ap is total port area of burner in m2

Ap = npΠ(dp)

2

4(3.27)

Where np and dp are number and diameter in m of ports.

The total flame port area must be chosen such that the mixture velocity through ports

should be lower than the stochiometric flame speed. Changes in entrainment ratio can change

the flame velocity.


Ap > Qm/4.26 > (2.08 ∗ 10−3)/4.26 > 0.0004896m2 > 489.6mm2

As port area total area of n ports of burner, it is given by

Ap = npΠ(dp)

2

4(3.28)

dp = port diameter

With reference to above equation, different combinations of burner port sizes and number

of burners can be derived. For conventional burner as number of ports 200, Port diameter

dp is evaluated and its value is 1.56 mm.

For the quenching distance between two ports an relation

While selecting the values either for or for number of ports, or vice versa, the flame stabi-

lization criterion is referred. Before selecting the above parameters the flame structure and

parameters affecting the stability of flames must be known. It designed in such a way that

it can balance the flow patterns within it to maintain a uniform flame size. For domestic

purpose, ports are circular in shape.

Cross lightening is important factor form for continuity of flame in short period of time. The

flame ignited at one end should immediately jump from one port to another to completely

lighten the burner. The distance between consecutive ports called as quench distance. [11]

Same procedure is followed and 5 burner designs are proposed at considered power, total

port area is obtained, and with varying number of ports, port diameter is obtained.


Chapter 4

Performance analysis of conventional

LPG stove Burner

Performance evaluation for any appliance plays a vital role in deciding its quantitative mea-

sure of satisfactory working. It has been observed that burner design and its construction

alone influences performance of an appliance. [15] In case LPG stove, performance of stove

is directly related to thermal efficiency of its burner. Larger the thermal efficiency better is

performance of stove. Now a day’s LPG is popular cooking fuel in urban as well as in rural

area too. Demand of LPG again directly related to population; but its source is limited. In

order to utilize the efficient fuel for cooking it must used to its maximum efficiency.

Properties of LPG Gas are given below:-

Burner design is the only factor affecting a stove performance. A burner design and

construction can serve as a quantitative index for further improved performance. Differ-

ent parameters in burner design are port depth, shape, slope, spacing, and provision for

secondary air flow. These parameters are divided in two parts as geometrical parameters,

which can be controlled by controlling dimensional parameters of a burner while designing.

And another groups contains parameters which partly depends on the fuel gas properties

and partly on atmospheric conditions. These are Flame lifting (Blow off), Flash back and

yellow tipping. These theories decide the acceptance limits of a burner design. A perfect

blend of geometric and flame stability limits gives an ideal burner. Ideally the flame for a

LPG stove burner is continuous, blue in color, without noise (silent) and stable. The blue

color indicates a complete combustion of fuel without giving rise to soot (carbon). Another

indication of blue color is it gives high temperature flame.

For improved design of a burner, efficiency of a burner currently used must be known.

Hence it is part of this work to evaluate the thermal efficiency of a stove. Performance of


Table 4.1: Properties of LPG Gas

Sr.No. Particulars LPG

1 Chemical Formulae60%Butane,

40% Propane Mix

2Max. Vapour Pressure Saturated in Kg/Cm2

16.87At 65 deg C

3 Gross calorific value in Kcal/kg. 11840

4 Specific gravity (liquid) at 15 deg C Water =1 0.543

5 Specific gravity (vapour) at 15 deg C air=1 1.75

6 Ideal combustion Ratio (Air to Gas) 28 to 1

7 Flammability limits (Upper) 9.10%

8 Flammability limits (Lower) 1.90%

9 Ignition Temperature (deg C) 488-502

10 Max. flame temperature (deg C) 1985

Volatility : evaporation temp.11 in 0C for 95(deg C) by vol. at 760 mm Hg pressure max. 2

12 Boiling Points (deg C) -22

16 Percent Gas in air for Maximum Flame Temperature 3.9

17Limits of Flammability (Lower)

1.95 9.75(% Gas in Gas /Air Mixture)( Upper)


a LPG stove is evaluated by the standard procedure given by Bureau of Indian standards

(BIS). Bureau of Indian Standards has published four Indian Standards for domestic LPG

Burning; out of these four, IS: 4246 covers the domestic LPG stove range. For different

cooking stove range manufacturing and testing various clauses are provided. The test has

been performed for different brass burners with varying no. of ports and at different ambient

temperatures.

The geometry of any burner includes internal diameter of burner, outer diameter, incli-

nation angels on inner and outer boundary and no of ports. The burner with the stove is

considered as reference for comparison purpose. The conventional burner is modeled in CA-

TIA V5 software with its actual dimensions. All the dimensions of the conventional burner

were measured using the Co-ordinate Measuring Machine (CMM) in Mechanical Engg. Dept.

Major dimensions like inner ring diameter and outer ring diameter and thickness are referred

by the dimensions of combustion chamber of a mixing tube, as the assembly of mixing tube

and burner top is known as burner system of a stove.

Another two brass burners are purchased which has identical geometry in all aspects

except no of ports on the flat surface. For the three burners thermal efficiency is evaluated

as per guidelines given by BIS. The precaution is taken to ignite a single burner at the time

of experiment.

Tests are performed on the PLANET, three burner stove, about three years old. The

designed thermal efficiency of the stove is 65%. The burners are made of brass material. Out

of the three, the larger burner of stove is chosen for performance analysis and this burner

is named as Conventional Burner (CB). For experimental work additional two burners are

purchased and named as B1 and B2. The burners B1 and B2 are identical in geometry, but

they differ in no of ports. Specifications of burner are given below.

Table 4.2: Burners specification under considerations

Material- Brass

No of Ports Total 200

Inner diameter 29.88mm

Outer diameter 93.24mm

Port size 1.766mm

Designed Thermal Efficiency 68%

Experiments are performed at different room temp to cover a wide range, with almost


similar pans. The digital weighing machine used for experimentation had least count 0.01

gm. A Digital thermometer with 0.01 0 C was used to note the temperature of water.

Table 4.3: Burner Types

Sr. No. Burner No. No. of ports Mass of Burner

1 CB(Conventional Burner ) 200 330 gm

2 B1 180 290gm

3 B2 169 310gm

The experimental set up for the test is given below.

Figure 4.1: Experimental setup for performance analysis of conventional burner.

Following procedure is followed for analysis:

• The gas cylinder mass by removing hose pipe is noted as M1 in Kg.

• Mass of water (Mw) and mass of aluminum vessel (Mal) are noted in Kg.

• Room Temperature (Rt) and Water temperature (T1) before experiment are noted in

0C .

• The gas is turned on for larger burner, when flame stabilized, the aluminum vessel

with water put on the pan support. Stirring is continued till final temp is noted.

• The water is heated till its temperature reaches up to 90 %. The flame put off. And

Maximum temperature of water is noted as (T2) in 0C .

• Cylinder again weighed and noted as M2 in Kg. Mass of fuel consumed is evaluated

from M1 and M2, as Mf = (M1- M2) in Kg.

ηth =(Mw ∗ Cw +MAl ∗ CAl) ∗ (T2 − T1)

Mf ∗ CV∗ 100 (4.1)

where

ηth = % thermal efficiency of burner,


Mw = Mass of water taken for experiment (Kg),

Cw = specific heat of water = 4190 kJ/kg-K,

MAl = Mass of water taken for experiment (Kg),

CAl = specific heat of aluminum vessel = 125 KJ/kg-K.

CV= Calorific value of LPG

The cylinder mass was noted before and after test every test by removing the hose pipe.

Only one burner of the appliance tested at a time. The pan was selected and loaded in

accordance with the requirements and placed centrally over the burner being tested.

Table 4.4: Experimental Results for cold Burner

Burner

Sr.Mass of Final Initial Cylinder Mass Thermal Flame Averagewater temp temp Before After Efficiency Temp. Thermal

No.test test degree C

(Kg) (0C) (0C) (Kg) (Kg) (%) EfficiencyMw (T2) (T1) (M1) (M2) η (%)

1 1.8 88 27.5 20.2 20 52.15 1932.45

53.61

Conventional 2 1.75 88.3 27 24.35 24.15 51.38 1930.23

Burner 3 1.8 91 29 20.4 20.2 53.45 1950.24

(CB) 4 1.95 90 30.8 20.5 20.3 55.26 1954.56

5 1.95 90 30.2 20.3 20.1 55.82 1955.71

1 1.58 95.3 19.1 3.61 3.587 49.3 1893.32

49.16

2 1.6 91.2 20 3.587 3.565 48.87 1895.23

Burner B1 3 1.55 89.9 19.8 3.565 3.545 51.19 1899.41

4 1.65 86.6 18.4 3.538 3.516 48.21 1896.27

5 1.55 92.4 20.1 3.515 3.493 48.23 1910.48

1 1.78 84.9 32.7 2.908 2.891 51.36 1932.361

Burner B2 2 1.8 84.5 32.3 2.888 2.87 49.03 1938.26 51.12

3 1.8 85.2 32.9 2.87 2.853 52.02 1941.24

4 1.82 85.8 32.6 2.852 2.835 53.48 1948.35

5 1.8 85.4 32.5 2.83 2.812 49.69 1936.14

Sample Calculation By using above given formula for thermal efficiency, a sample

calculation for a reading is - Thermal Efficiency = (1.6 X 4.187 + 0.333 X 0.91) X (91.2-

20)/(0.022 X 46350 ) * 100

= 498.55877/1019.7 * 100

= 48.892%


In order to notice the effect number of ports or distance between ports on its performance,

additional two burners (Burner B1 and Burner B2) are also tested with same procedure. As

the burners are different in port numbers only, their performance represents effect of port

area on thermal efficiency.

Variations are maintained in the test procedure by changing either the port area or ambient

temperature. 5 Efficiency tests are performed for a burner at constant temperatures for a

burner under observation. This is achieved by keeping a fixed time of experiment within a

day. The condition for the test was only the burner surface to be tested should be at room

temperature i.e. it should not preheat and only single burner should be ignited while testing.

Exact constant temperature maintaining is not attained due to environmental conditions.

Other burners also tested with same procedure.

Effect of Warm (preheated) Burner: In the theoretical efficiency calculated as per

BIS, only condition and convection are considered. Radiation mode is totally neglected.

To know the amount of heat emitted by burner surface, use of preheated burner named as

warm burner is focused. The common use any preheated quantity is generally to improve

the efficiency of an appliance. Here the same concept is decided to apply.

A Warm Burner (Preheated burner) is a burner which when tested has some initial sur-

face temperature higher than ambient temperature. This warming is due to use of the burner

before the experiment. In previous process experiments were performed for a complete cool

burner.

Preheated effect of burner was considered by adding some porous medium in previous lit-

eratures. In conventional burners this effect was untouched. Hence in order to study this

effect on efficiency, same test was carried out but with a little different way. For regular

testing, one burner was tested per day at specific time when burner was totally cool. That

is its walls are at room temperature. To conduct the test for effect of warming on thermal

efficiency, a series of experiments were performed within an interval of 15 min for the same

burner after the first reading is noted. Similar burner at same temperature was tested with

regular procedure. And the efficiency is calculated for both cases.

At constant temperatures, efficiency of a burner at ambient temp and same burner with

warm burner (Preheated Burner) are note down by following the same procedure. And a

considerable gain in every burner is observed. Such experiments are repeated for five times

for each burner.

The results are arranged in following table.


Table 4.5: Experimental Results for Warm Burner

Burner

Sr.Mass of Final Initial Cylinder Mass Thermal Averagewater temp temp Before After Efficiency Thermal

No.test test

(Kg) (0C) (0C) (Kg) (Kg) (%) EfficiencyMw (T2 ) (T1) (M1) (M2) η (%)

1 1.95 93.5 30.6 19.45 19.429 55

Burner 2 1.9 92.8 30.8 19.409 19.389 55.52

B2 3 1.89 92.6 30.2 19.389 19.37 58.52 57.91

4 1.95 91.8 30.8 19.37 19.351 58.95

5 1.98 93.5 30.7 19.351 19.332 61.58

Table 4.6: Experimental results for cold and warm burners

Burner Thermal Efficiency

At Ambient Temp With warm Burner

52.6 52.92

53.1 53.98

CB 52.4 55.59

52.87 58.38

53.1 62.46

49.82 51.96

B1 49.5 54.56

48.95 56.75

49.63 60.15

48.65 63.76

53.61 54.99

B2 52.3 55.52

53.36 58.522

52.45 58.94

53.84 61.58


Chapter 5

CFD Analysis of Burner

Computational fluid dynamics (CFD) is a computer-based mathematical modeling tool that

has proven to be a valuable tool in optimizing combustion equipments and gas burners. Us-

ing CFD simulation, it is easy to get accurate data measurement, and it incorporates the

solution of the fundamental equations of fluid flow and other allied equations. It also reduces

the times and cost of development new burner. The main reason for doing the simulation is

the measurement of the detailed distributions of velocity, temperature and gas composition

are very difficult for practical burner.

Computers are used to compute such task by using specific software that allows complex

calculation for simulation of intended flow process. CFD is distributed in three phases as-

• Pre-processing, in which geometry creation is performed using a CAD tool.

• Mesh generation of a suitable computational domain to solve the flow equations on

and

• Solving with post processing, or visualization of a CFD code’s predictions.

Now a-days CFD is widely accepted and validated engineering tool for industrial applica-

tions. In our case, CFD - FLUENT is used. It uses the science of predicting fluid flow, heat

and mass transfer, chemical reactions and related phenomena by solving numerically the sets

of governing mathematical equations. The results of CFD analysis are relevant in conceptual

studies of new design, detailed product development, troubleshooting and redesigning [15]

Advantages of CFD

1. The changes to analysis at any time during setup, solution, or post processing phase


are allowed by the software. This refines our designs efficiently and saves time. It

enables the interface easy. The CAD geometries are imported and adapted easily.

2. Solver enhancements and numerical algorithms that decrease the time of solution.

Bigger problems are solved faster. And it has been proven on the widest possible

variety of platforms in the industry.

3. FLUENT’s post processing provides several levels of reporting; hence it is possible

to satisfy the needs and interests of all audiences. Quantitative data analysis can be

as rigorous as we require. Results can be communicated with impact due to high

resolution images and animations. A numerous data export options are available for

integration with structural analysis and other computer aided engineering (CAE) soft-

ware programs. It is capable to complete meshing flexibility, solving flow problems

with unstructured meshes that can be generated through the complex geometries.

Modeling and Simulation

A conventional burner is modeled using CATIA-V5 software. And CFD - FLUENT 6.3 is

used for simulation in the flow and combustion of LPG. This software allows simulation of

flow of fluid and heat and mass transfer in complex geometries.

Modeling: Major dimensions of conventional burner are measured using CMM (Co-

ordinate Measuring Machine) in Mechanical Engg. Using sketcher a two dimensional geom-

etry is created. Later by using revolve command to 3600 the solid burner is modeled.

Figure 5.1: 2-D drawing for conventional burner


On the inclined flat surface the through holes (ports) are generated by pocket command.

The complete model of conventional burner and Burner B1 are shown below. Similarly

Figure 5.2: Burner Models a) Conventional Burner b) Burner B1 c) Burner B2

Simulation By using the CFD - FLUENT 6.3, the problem solving steps involves-

• The problem identification,

• Grid creation,

• Solver execution and

• Analysis of the result.

In current work, the conventional burner and other two burners were modeled and sim-

ulated. Velocity vector and flame temperatures are studied for these burners.

• Select Domain as a Fluid Domain for the analysis purpose before meshing of the burner

model.

• After the domain selection. create named selection such as Fuel inlet, Fuel Outlet, Air

Inlet to give inlet for fuel and air respectively


Figure 5.3: Create Named Selection

• Meshing:

In Meshing

– Use advanced size function: off

– Relevance centre: fine

– Element size:- 3e−2 mm

– Smoothing:- High

Figure 5.4: Model after Meshing

• import model in to the fluent


Figure 5.5: Model in Meshing

For the analysis setup, select model in fluent as follows

• Energy Equation: on

• K-Epsilon (2 equation)

• Radiation: P1

• Species: Non Premixed Combustion

• Species: Non Premixed Combustion

Figure 5.6: Model Selection

Boundary Conditions:-


• At Fuel inlet Mention the Mass flow rate of the fuel for respective case

• At Air inlet Mention the Mass flow rate of the air for respective case

Figure 5.7: Boudary condition

Figure 5.8: Number of iteratiions and calculation of solution


Figure 5.9: Scaled Residuals After solution

Results after analysis

Flame temperature

Figure 5.10: Plot for Flame Temperature


Table 5.1: Comparison of Experimental results with CFD results

Sr. No. Burner No. Of Ports Flame FlameTemperature Temperature

(0C) (0C)

1 Conventional Burner 200 1967.24 1944.63

2 B1 180 1896.34 1898.94

3 B2 165 1945.32 1939.27

Figure 5.11: Flame Temp experimental and Computational


Chapter 6

Results and Discussion

1. Burner of domestic LPG stove is designed based on blend of geometrical parameters

and flame stability criterion. Geometrical parameters normally associated with design of

a burner while flame stability criterion is to be considered for a complete combustion and

better utilization of fuel. Total burner port area is a key parameter to decide the combustion

quality. Hence for a range of power output burner port area is calculated. And then by

varying the number of ports, varying port area is obtained. And such combinations of Np

and Dp are designed.

2. The experiments were carried out for three burners at a wide range of temperatures.

The water boiling test given by BIS (IS: 4246:2002) was used to evaluate the thermal effi-

ciency as a measure of performance coefficient. Although the designed thermal efficiency of

a conventional burner specified on its label is 65%, experimentally it found to be about 53

% for a conventional burner i. e. The existing burner of stove.

A blue, clean and silent flame was the output foe CB and Burner B2. Yellow tipping was

totally absent in all cases. In Burner B1, the flame blow off was exist at joint of burner top

and the combustion chamber edge.

It is observed that Conventional burner (200 ports) gives about 53 % efficiency while for

burner B1 and Burner B2 it is found to be about 49% and 51% respectively. Low Th. Eff.

For burner B1 is due to the flame blow off during burning.

Variation in thermal efficiency directly relates the influence of port area on its perfor-

mance. The experiments were conducted at constant power output and about constant

ambient temperature, to study its effect on burner performance. It shows significant impact

on burner efficiency. Thermal efficiency found to directly relate with ambient temperature.

This is due to temperature gradient between the atmospheric temperature and the burner

surface. As temperature increases, the temperature gradient between burner surface and at-

mosphere decreases, reducing convective heat loss and resulting in higher thermal efficiency.


Figure 6.1: Effect of warm burner on thermal efficiency for CB

3. The term warm in this test is referred to a burner which has some initial higher tem-

perature before it is lighten. Radiation effects are neglected while calculating the efficiency

in current procedure. The amount of heat radiated by a burner is wasted. To account this,

the tests are repeated with a fixed and small interval of time. Once the first reading is noted,

next four tests were conducted in series. Every time the utensil was changed to avoid the

warming effect of the utensil to affect on burner performance. By this process a higher value

of efficiency for all burners is achieved compared with regular process. Maximum efficiency

for CB is attained is 61%, which is about 8 % higher than the previous one. Similarly Burner

B1 and B2 also show a considerable gain in thermal efficiency.

For conventional burner, maximum efficiency attained was about 62In all burners ambient

temperature gives direct influence on thermal efficiency.

During the operation of a stove, the burner will warm up, which in turn will preheat the

air-fuel mixture as it passes through the burner assembly. There are two effects, both of

them are: (a) The burning velocity of the Air-fuel mixture increases with temperature. This

leads to a better flame stability at high aeration and high port loading. (b) As the air-fuel

mixture passes through a hot burner assembly, the mixture temperature will rise, leading

to an increase in volume, a decrease in density and an increased flow resistance; hence air

entrainment decreases. Consequently the flames will become more stable as the appliance

warms up.

4. The flow analysis is performed using FLUENT 6.3, tool. Boundary conditions are

derived from the experimental analysis. Flame temperature of the flow of mass flow is

calculated using FLUENT. Flame temperatures results obtained from CFD and those from


Figure 6.2: Effect of warm burner on thermal efficiency for B1

Figure 6.3: Effect of warm burner on thermal efficiency for B2


experimental values are observed to be deviated b about 7


Chapter 7

Conclusion

With a plenty of advantages, LPG is has proven to the most popular fuel. Along with auto

fuel and several industrial applications it is used primarily for domestic cooking worldwide.

Due to its availability at subsidized price, it conquers the major market of cooking fuel in

India. Rising population and depleting sources of fuels, justifies the importance of conser-

vation of this ideal fuel. This may be possible if the fuel is at least used to its maximum

efficiency. The stoves manufactured in India are generally labeled with maximum thermal

efficiency in a range 65- 68 %. But the running efficiency is less. 1. Efficiency of any ap-

pliance is primarily depends on its design and the combustion of fuel is being used. Burner

design analysis is carried out in the present work for the designed thermal efficiency given

by manufacturer of stove. Based on Flame stability characteristics criterion, all parts of a

burner system is designed. Total Port area of a burner is the key decision factor. 2. Perfor-

mance of conventional domestic LPG stove burner was tested for a three burner gas stove,

as per the guidelines given by BIS (IS 4246: 2002). Larger burner of the three was selected

for investigation. The Conventional burner (CB), burner B1 and burner B2 are tested for

thermal efficiency. Experiments were performed at range room temperatures as well as with

different utensils of nearly similar dimension. For constant temperature effect no of ports

has been studied. Result shows considerable variations in thermal efficiency with varying

number of ports. For CB (200 ports), efficiency is about 53% where as for burners B1 (180

ports) and B2 (165 ports) its value is 49 % and 51 % respectively. Hence it is concluded that

thermal efficiency is directly related with burner port area. This indirectly denotes effect of

quenching distance between the ports on thermal efficiency. As the ports are reducing with

same size, quenching distance is increasing; flame takes a more time to jump from successive

ports to maintain the continuity. For burner B2, flame blow off phenomenon was observed.

And it gives its direct adverse effect on thermal efficiency. Also the performance of a burner

found to be affected by ambient temperature. As at higher temperature, the temperature


gradient between burner surface and atmosphere is low, it results in higher thermal efficiency.

The use of warm (preheated) burner, maximum thermal efficiency of burner B2 goes

up to 61From the results of warn burners, around 8-103. The computational results are

compared with the experimental flame temperatures. The numerical error of the prediction

of these quantities was verified to less than 5


Bibliography

[1] Pankaj P. Gohil, And Salim A. Channiwala, ”EXPERIMENTAL INVESTIGATION

OF PERFORMANCE OF CONVENTIONAL LPG COOKING STOVE ” Fundamen-

tal J. Thermal Science and Engineering, Vol. 1, Issue 1, 2011, Pages 25-34 Published

online at http://www.frdint.com/ Keywords and phrases : conventional burner, thermal

efficiency, emission. *Corresponding author Received June 21, 2011 2011. Fundamental

Research and Development International.

[2] Performance of Insulated LPG Burner with Ball Bearings as Porous Medium” PJST

Journal .

[3] Mohd. Yunus Khan And Anupriya Saxena, ”Performance Of LPG Cooking Stove Using

Different Design Of Burner Heads ” International Journal of Engineering Research and

Technology (IJERT) Vol. 2 Issue 7, July - 2013 ISSN: 2278-0181.

[4] N. K. Mishra, P. Muthukumar, Subhash C. Mishra, ”Performance Tests on Medium-

Scale Porous Radiant Burners for LPG Cooking Applications”, International Journal of

Emerging Technology and Advanced Engineering Volume 3, Special Issue 3: ICERTSD

2013, Feb 2013, pages 126-130 An ISO 9001:2008 certified Int. Journal, ISSN 2250-

2459, Presented at International Conference on Energy Resources and Technologies for

Sustainable Development, 07-09 February 2013, Howrah, India.

[5] P. Muthukumar, Piyush Anand, Prateek Sachdeva, ”Performance analysis of

porous radiant burners used in LPG cooking stove”, International Journal Of En-

ergy And Environment. Volume 2, Issue 2, 2011 pp.367-374 Journal homepage:

www.IJEE.IEEFoundation.org, ISSN 2076-2895.

[6] V.K. Pantangi, Subhash C. Mishra, P. Muthukumar, Rajesh Reddy ”Studies on porous

radiant burners for LPG (liquefied petroleum gas) cooking Applications”, journal home-

page: www.elsevier.com/locate/energy Energy 36 (2011) 6074e6080.


[7] Apinunt Namkhat and Sumrerng Jugjai , ”The Effect of Primary Air Preheat on the Pri-

mary Aeration of a Self- aspirating Burner”, The First TSME International Conference

on Mechanical Engineering 20-22 October, 2010, Ubon Ratchathani.

[8] Sumrerng Jugjai and Surachai Sanitjai, ” Parametric Studies of Thermal Efficiency in

a Proposed Porous Radiant Recirculated Burner(PRRB): A Design Concept for the

future Burner”, RERIC International Energy Jounal: Vol. 18, No. 2, Dec. 1996.

[9] Jos M. N. Rodrigues1, Edgar C. Fernandes, ”Stability Analysis and Flow Character-

ization of Multi-Perforated Plate Premixed Burners”, 17th International Symposium

on Applications of Laser Techniques to Fluid Mechanics Lisbon, Portugal, 07-10 July,

2014.

[10] Walter M. Berry, I. V. Brumbaugh, G. F. Moulton, G. B. Shawn,” Technologic Papers Of

The Bureau of Standards”, September 6 1921. Department Of Commerce, Washington.

[11] H. S. Couto, J.B. F.Duarte and D. Bastos-Netto, ”Domestic Range Burner Design

Procedure” , The Seventh Asia-Pacific International Symposium on Combustion and

Energy Utilization December 15-17, 2004, Hong Kong SAR.

[12] John H. Eiseman, Elmer R. Weaver, and Francis A. Smith, ”A Method For Determining

The Most Favorable Design Of Gas Burners”, RP446 Washington, March 19, 1932.

[13] C. Tierney and A.T. Harris, ”Materials Design and Selection Issues in Ultra-Lean Porous

Burners” Journal of the Australian Ceramic Society Volume 45[2], 2009, 20-29.

[14] Walter B. Kirk and James C. G r i f f i t h s, ” APPLYING FUNDAMENTAL CON-

CEPTS TO TEE EECINEXFIING DESIGN OF APPLIANCE BUIWEBS” American

Gas Association Laboratories, Cleveland, Ohio, Chicago, I l l i n o i s , Meeting, Septem-

ber 7-12, 1958.

[15] Channing W. Wilson and George E. McGowan ”Performance Coefficients and Flame

Stability of Gas Appliance Burners”, Research Department, Baltimore Gas and Electric

Company, Baltimore, Maryland.

[16] Dr David Fulford, ”Biogas Stove Design A short course” Kingdom Bioenergy Ltd Orig-

inally written August 1996 Used in MSc Course on ”Renewable Energy and the Envi-

ronment” at the University of Reading, UK for an Advanced Biomass Module.

[17] J.B. Singh and G.C. Pant , ”Experimental Investigation and Mathematical Modelling

to Study the Premixed Laminar Flame Propagation”, Defence Science Journal, Vol. 57,

No. 5, September 2007, pp. 661-668 2007, DESIDOC.


[18] Catharine TIERNEY, Susie WOOD, Andrew T. HARRIS and David F. FLETCHER,

”Computational Fluid Dynamics Modelling Of Porous Burners ”, Seventh International

Conference on CFD in the Minerals and Process Industries CSIRO, Melbourne, Aus-

tralia 9-11 December 2009.

[19] Musthafa Abdul Mujeebu, Mohammad Zulkifly Abdullah, and Mohammed Zuber, ”Ex-

periment And Simulation To Develop Clean Porous Medium Surface Combustor Using

Lpg”, Is? Bilimi ve Tekni?i Dergisi, 33, 1, 55-61, 2013, J. of Thermal Science and

Technology, ISSN 1300-3615.

[20] Obada David Olubiyi, ”Design, Construction And Performance Evaluation Of A Bio-

gas Burner”, (M.Sc/ENG/5665/09-10), An Msc Thesis Submitted To The Postgraduate

School, Ahmadu Bello University Zaria in Partial Fulfilment Of The Requirements For

The Award Of Masters Of Science (M.Sc) Degree In Mechanical Engineering Depart-

mentofmechanicalengineering, Faculty Of Engineering Ahmadu Bello University Zaria.

Nigeria June, 2012.

[21] DRAFT BUREAU OF INDIAN STANDARDS DRAFT MANUAL FOR CERTIFICA-

TION OF LPG GAS BURNING APPLIANCES, (IS 4246; IS 4473; IS 4760 AND IS

11480), Bureau of Indian Standards, Manak Bhavan, 9, Bahadur Shah Zafar Marg, New

Delhi.

[22] Schedule No- 9 Domestic Liquefied Petroleum Gas (LPG) Stoves, Revision: 2, Date:

11.12.2013.

[23] Jugjai, S. and Rungsimuntuchart, N. (2002). High efficiency heat-recirculating domestic

gas burners, Experimental Thermal and Fluid Science, vol. 26(5), April 2002, pp. 581 -

592.

[24] Dr. Gunther Bethold Managing Director, Dr.Luca Barozzi, Ing. Massimo Dotti, Ing.

Massimo Gilioli, Dr. Gabriele Gangale, ”Gas Burner Technology and Gas Burner Design

for Application”.

[25] Aruna Devadiga, Prof. Dr. T. Nageswara Rao, ” Optimizing Bunsen burner Perfor-

mance Using CFD Analysis” International Journal of Modern Engineering Research

(IJMER) www.ijmer.com Vol. 3, Issue. 5, Sep - Oct. 2013 pp-2773-2785 ISSN: 2249-

6645 www.ijmer.com 2773.

[26] Subsidies to Liquefied Petroleum, Gas in India: An overview of recent reforms, March

2014.


[27] Shuhn-Shyurng Hou and Ching-Hung Chou, ”Parametric Study of High-Efficiency

and Low-Emission Gas Burners”, Hindawi Publishing Corporation, Advances in

Materials Science and Engineering, Volume 2013, Article ID 154957, 7 pages

http://dx.doi.org/10.1155/2013/154957.

[28] Apurva Chandra, ” World LPG Forum 2010-MadridWorld 2010World 2010-Madrid ”


performance and design analysis of domestic lpg stove

Documents

jalgaon maharashtra

jalgaon ms ideclarationi

degree of masterof engineering

candidates project

project reportprovides

supportedby s

feeling of gratitude

myoriginal work