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TRANSCRIPT
Gaseous Species Measurements of Alternative Jet Fuels in
Sooting Laminar Coflow Diffusion Flames
by
Parham Zabeti
A thesis submitted in conformity with the requirements
for the degree of Master of Applied Science
Graduate Department of Mechanical and Industrial Engineering
University of Toronto
© Copyright by Parham Zabeti 2010
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Abstract
Gaseous Species Measurements of Bio-Jet Fuels in a Laminar Coflow Diffusion Flame
Parham Zabeti
Master of Applied Science
Graduate Department of Mechanical and Industrial Engineering
University of Toronto
2010
The gaseous species concentration of Jet A-1, GTL, CTL and a blend of 80 vol.% GTL and 20
vol.% hexanol jet fuels in laminar coflow diffusion flames have been measured and studied. These
species are carbon monoxide, carbon dioxide, oxygen, methane, ethane, ethylene, propylene, and
acetylene. Benzene and propyne concentrations were also detected in CTL flames. 1-Butene has
been quantified for the blend of GTL and hexanol flame.
The detailed experimental setup has been described and results from different flames are
compared. The CO is produced in a same amount in all the flames. The CTL flame had the
largest and GTL/hexanol flame had lowest CO2 concentrations. The results indicate that GTL
and GTL hexanol blend flames produce similar concentrations for all the measured hydrocarbon
species and have the highest concentration among all the jet fuels. The experimental results from
Jet A-1 fuel are also compared with numerical studies by Saffaripour et al.
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Dedication
To Tiam, my adorable new born nephew, and to all future generations.
May the world be a peaceful place for them to grow, fall in love and flourish.
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Acknowledgments
I would like to thank my mother whose patience and blessing made choosing the right path for
my life possible. My greatest appreciation to my always supportive brother, Pedram. Without his
encouragement and insight, I would never reach where I am today.
My extended gratitude goes to Professor Murray Thomson for his comprehensive prospect
and wise judgement on this project. Murray has been an inspiration to my academic and personal
lives throughout my studies at the University of Toronto.
I am grateful to know Mahsa, my best friend during last two years. With no doubt she will
be one of the most sincere, intelligent and friendliest characters I would ever encounter in my
life. My thesis also benefits from her artistic talents in some of the drawings in this dissertation.
Thank you for being there for me in all the ups and downs.
Gratefulness to my colleagues at Combustion Research Group, specifically my labmates,
Meghdad Saffaripour, Coleman Yeung and Carlos Martinez who created a warm and welcoming
work environment. A special thanks to my former colleague, Dr. Mani Sarathy who helped me
since the first days of my graduate studies from answering my endless questions to setting up my
experimental apparatus. His step by step teaching throughout my first year of Master’s is much
appreciated. I still always enjoy our conversations and try to learn from you. Also, I was fortunate
to learn a lot from other talented group members such as Dr. Seth Dworkin.
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I would also like to acknowledge OGS, ALFA-BIRD for funding this study and NRC for
donating the burner to the Combustion Research Group.
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List of Content
ABSTRACT ........................................................................................................................................................ II
DEDICATION ................................................................................................................................................. III
ACKNOWLEDGMENTS ................................................................................................................................ IV
LIST OF CONTENT ........................................................................................................................................ VI
LIST OF TABLES ............................................................................................................................................. IX
LIST OF FIGURES ............................................................................................................................................ X
LIST OF APPENDICES ................................................................................................................................ XIV
ACRONYMS ................................................................................................................................................... XV
1. INTRODUCTION ..................................................................................................................................... 1
1.1 RESEARCH MOTIVATION .............................................................................................................................. 2
1.2 RESEARCH OBJECTIVES ................................................................................................................................. 3
1.3 RESEARCH EXECUTION ................................................................................................................................. 4
2. BACKGROUND RESEARCH .................................................................................................................. 5
2.1 AVIATION FUELS ............................................................................................................................................ 5
2.1.1 Physical and Chemical Properties .............................................................................................................. 6
2.1.2 Proposed Alternative Jet Fuels .................................................................................................................. 9
2.1.2.1 Fischer-Tropsch Synthetic Kerosene ........................................................................................................... 9
2.1.2.2 Bio-Derived Synthetic Paraffinic Kerosene (or BTL) ............................................................................... 13
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2.1.2.3 Bio-Alcohols .............................................................................................................................................. 14
2.1.2.4 Other Blends .............................................................................................................................................. 15
2.1.3 Surrogate of Jet Fuels ............................................................................................................................. 15
2.2 JET ENGINE DESIGN .................................................................................................................................... 16
2.2.1 Emissions .............................................................................................................................................. 17
2.3 FUNDAMENTALS OF COFLOW LAMINAR DIFFUSION FLAME ................................................................... 18
2.3.1 Governing Equations for Laminar Diffusion Flame ............................................................................... 20
2.3.2 Flame Liftoff ......................................................................................................................................... 20
2.3.3 Flame Length (or Visible Flame Height) ................................................................................................ 20
2.4 SOOT FORMATION IN COFLOW FLAMES ................................................................................................... 22
3. EXPERIMENTAL APPARATUS & ANALYTICAL METHODOLOGY .......................................... 28
3.1 FUEL SUPPLY ................................................................................................................................................ 30
3.2 FUEL VAPORIZATION SYSTEM .................................................................................................................... 33
3.3 COFLOW DIFFUSION FLAME BURNER ........................................................................................................ 36
3.3.1 What is a Suitable Flame? ..................................................................................................................... 37
3.4 EXPERIMENTAL TEMPERATURE AND FLOW SETTINGS ............................................................................ 39
3.4.1 Flow Controls ....................................................................................................................................... 39
3.4.2 Temperature Settings ............................................................................................................................. 40
3.5 GAS SAMPLING SYSTEM .............................................................................................................................. 41
3.5.1 Sampling Apparatus .............................................................................................................................. 41
3.5.2 Sampling Procedure ............................................................................................................................... 44
3.5.2.1 Detecting the Leaks ................................................................................................................................... 44
3.5.2.2 Centring the Burner ................................................................................................................................... 46
3.5.2.3 Sampling the Flame ................................................................................................................................... 47
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3.6 ANALYTICAL TECHNIQUES ......................................................................................................................... 50
3.6.1 Principles of Gas Chromatography .......................................................................................................... 50
3.6.1.1 GC–TCD .................................................................................................................................................. 51
3.6.1.2 GC–FID .................................................................................................................................................... 53
3.6.1.3 Calibration of Gas Chromatography ......................................................................................................... 56
3.6.2 Non-Dispersive Infrared Analysis .......................................................................................................... 59
4. RESULTS & DISCUSSIONS .................................................................................................................. 61
4.1 JET A-1 FLAME............................................................................................................................................. 62
4.2 GAS-TO-LIQUID FLAME .............................................................................................................................. 70
4.3 COAL-TO-LIQUID FLAME ........................................................................................................................... 73
4.4 GAS-TO-LIQUID BLEND WITH HEXANOL FLAME .................................................................................... 76
4.5 SPECIES COMPARISON ................................................................................................................................. 78
4.6 COMPARISON WITH COFLOW ETHYLENE DIFFUSION FLAME ................................................................. 84
5. CONCLUSIONS & RECOMMENDATIONS ...................................................................................... 86
5.1 CONCLUSIONS .............................................................................................................................................. 86
5.2 IN-PROGRESS WORK ................................................................................................................................... 88
5.3 FUTURE WORKS ........................................................................................................................................... 88
5.3.1 Recommendations .................................................................................................................................. 89
BIBLIOGRAPHY .............................................................................................................................................. 91
APPENDICES ................................................................................................................................................. 100
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List of Tables
Table 2-1: Specific properties of aviation fuels including the experimented Jet A-1 ..................... 7
Table 2-2: Comparison between key thermochemical and physical properties of Shell Jet A-1,
ethanol and hexanol ...................................................................................................................... 14
Table 2-3: Surrogates for alternative jet fuels suggested by Dagaut et al .................................... 16
Table 2-4: Smoke point analysis of experimented jet fuel ........................................................... 27
Table 3-1: Summary of Jet A-1 composition analysis by group and carbon number ................. 31
Table 3-2: Specific heat capacity and thermal conductivity of experimental fuels ...................... 32
Table 3-3: Fuel flowrate settings on liquid flow controller in terms of C14H30 fuel flowrates ..... 39
Table 3-4: A sample of comparison between measured and literature FID relative molar response
factors for a range of organic molecules ....................................................................................... 59
Table 4-1: Acetylene level comparison in ethylene and Hex20-GTL coflow diffusion flames ... 84
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List of Figures
Figure 2.1: Simplified block diagram of GTL process to produce FT-SPK .............................. 11
Figure 2.2: Simplified block diagram of Sasol CTL process to produce FSJF ........................... 12
Figure 2.3: Simplified block diagram of thermochemical conversion route for Bio-SPK ......... 13
Figure 2.4: A typical jet engine drawing showing the three main steps: compression, combustion,
expansion ...................................................................................................................................... 17
Figure 2.5: Soot formation and destruction zones in laminar diffusion flames ........................... 23
Figure 2.6: The H-abstraction–C2H2-addition (HACA) mechanism of PAH formation . ........ 24
Figure 2.7: A rough picture of soot formation ............................................................................ 25
Figure 3.1: Schematic diagram of the experimental setup ........................................................... 29
Figure 3.2: Comparison between main HC groups composition in GTL and CTL fuels .......... 33
Figure 3.3: Bronkhorst® liquid delivery system with vapour control ........................................... 35
Figure 3.4: Schematic diagram and section cut of a coflow burner ............................................. 36
Figure 3.5: Schematic of microprobe head ................................................................................... 43
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Figure 3.6: The centring process ................................................................................................. 46
Figure 3.7: Schematic of dual column GC-TCD setup .............................................................. 52
Figure 3.8: Schematic of dual column GC-FID setup ................................................................ 54
Figure 3.9: GC-FID column oven temperature program ............................................................ 55
Figure 3.10: Permeation tube setup .............................................................................................. 57
Figure 4.1: Bottom portion of a typical Jet A-1 flame ................................................................ 62
Figure 4.2: Jet A-1 CO & CO2 centreline concentration profiles .............................................. 63
Figure 4.3: Jet A-1 CO & CO2 radial concentration profiles (a) z = 12 mm (b) z = 14 mm ..... 64
Figure 4.4: Jet A-1 centreline concentration profiles (a) CH4 & C2H6 (b) C2H4, C2H2 & C3H6 64
Figure 4.5: Jet A-1 species radial concentration profiles (a) z =12 mm, (b) z = 14 mm ............. 65
Figure 4.6: Computational (model) and experimental (exp) comparisons of CO & CO2 mole
fractions for Jet A-1 flame along (a) centreline and (b) radial (z = 12 mm) profiles ................... 66
Figure 4.7: Computational (model) and experimental (exp) comparison of species centreline
mole fractions for Jet A-1 flame along (a) CH4 & C2H6 (b) C2H4 & C2H2 (c) & C3H6 ........... 66
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Figure 4.8: Computed temperature isotherm for Jet A-1 laminar coflow diffusion flame by
Saffaripour et al. ........................................................................................................................... 67
Figure 4.9: GTL flame during sampling at the height of z = 30 mm in the flame ..................... 70
Figure 4.10: GTL jet fuel CO and CO2 centreline concentration profiles ................................. 71
Figure 4.11: GTL jet fuel species radial concentration profiles (a) z =14 mm, (b) z = 18 mm ... 71
Figure 4.12: GTL centreline concentration profiles (a) CH4 & C2H6 (b) C2H4, C2H2 & C3H6 . 72
Figure 4.13: CTL highly sooting flame ....................................................................................... 73
Figure 4.14: CTL jet fuel CO and CO2 centreline concentration profiles ................................. 74
Figure 4.15: CTL jet fuel centreline concentration profiles (a) CH4 & C2H6 (b) C2H4, C2H2 &
C3H6 (c) C3H4 & C6H6 ................................................................................................................ 75
Figure 4.16: Hex20-GTL jet fuel CO and CO2 centreline concentration profiles .................... 77
Figure 4.17: Hex20-GTL jet fuel centreline concentration profile (a) CH4 & C2H6 (b) C2H4,
C2H2 & C3H6 (c) C4H8 ................................................................................................................ 78
Figure 4.18: CO & CO2 centreline concentration profiles comparison of experimental fuels .. 79
Figure 4.19: Species centreline concentration comparison between CTL jet fuel and Jet A-1 ... 80
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Figure 4.20: Species centreline concentrations comparison between CTL & GTL jet fuels ..... 81
Figure 4.21: Species centreline concentrations comparison between Jet A-1 & GTL jet fuels .. 82
Figure 4.22: Species centreline concentrations comparison between GTL & Hex20-GTL jet
fuels ............................................................................................................................................... 83
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List of Appendices
Appendix A:
Part (I) – Jet A-1 Fuel Composition
Part (II) – Jet Fuels Thermophysical Properties
Part (III) – Jet A-1 Thermodynamic Properties
Appendix B:
Step by Step Sample Analysis of GC-TCD
Appendix C:
Sample Gas Chromatograms
Appendix D:
Governing Equations
Appendix E:
Sample Hand Calculation
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Acronyms
ALFA-BIRD Alternative Fuels and Biofuels for Aircraft Development
ARC Alberta Research Council
ASTM American Society for Testing and Materials
BTL Biomass-to-Liquid
CEM Controlled Evaporative Mixer
Ci Hydrocarbon with i number of carbon(s)
CTL Coal-to-Liquid
EFC Electronic Flow Control
FID Flame Ionization Detector
FS Fused Silica
FSJF Fully Synthetic Jet Fuel
FT Fischer-Tropsch
GC Gas Chromatography
GHG Green House Gas
GSV Gas Sampling Valve
GTL Gas-to-Liquid
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HC Hydrocarbon
Hex20-GTL 20 vol.% Hexanol and 80 vol.% Gas-to-Liquid Blend
IATA International Air Transport Association
IFP Institut Francais du Petrole
LOD Limit of Detection
LOQ Limit of quantification
LPG Liquefied Petroleum Gas
NDIR Non-Dispersive Infrared
NG Natural Gas
NRC-IAR National Research Council Canada-Institute for Aerospace Research
PAH Polycyclic Aromatic Hydrocarbon
PM Particulate Matter
RT Retention Time
SPK Synthetic Paraffinic Kerosene
SS Stainless Steel
STP Standard Temperature Pressure
TCD Thermal Conductivity Detector
VOC Volatile Organic Compound
1
Chapter 1
1. Introduction
There is an emerging demand for alternative and sustainable energy sources to replace the
conventional non-renewable energy supply. Currently, aviation consumes about 8% of total fossil
fuels burned. This amount is equivalent to 12% of the fuel consumption of the entire
transportation sector, compared to 75 – 80% dedicated to road transport [1]. Particulate matter
(PM), volatile organic compounds (VOC’s), and greenhouse gases (GHG), such as carbon
dioxide (CO2), nitrogen oxides (NOX) and unburned hydrocarbons (HC) (e.g. methane)
emissions are in direct proportion to the fuel consumption.
Nonetheless, air traffic is steadily increasing (a 60% increase by 2020 is expected [2]), and
energy supply from conventional mineral kerosene fuel is decreasing. Unlike other transportation
sectors, aviation currently has no viable alternative to burning fossil fuels. Nuclear and electric
power are not suitable alternatives with current technologies [3]. Besides these concerns, volatile
fuel prices are damaging the airline industry. For example, Air Canada, and most recently, Japan
Airlines Corp. filed for bankruptcy mainly as a result of unstable fuel costs1.
1 Various sources and articles from Reuter’s News website (ca.reuters.com). Accessed on May 2010.
2
1.1 Research Motivation
The reduction of GHG emissions is the top priority in tackling global warming. A major source
of emissions, the transportation sector, including aviation, is working hard towards this goal.
Based on the reasons mentioned on the last page, scientists, politicians and economists are
investigating alternative fuels for aviation. The combustion study of alternative fuels is a vital part
of this investigation. Recently, European programs, such as Sustainable Way for Alternative
Fuels and Energy for Aviation and ALFA-BIRD (Alternative Fuels and Biofuels for Aircraft
Development), and American programs by Defense Energy Support Center and Air Force
Certification Office have begun to study and certify novel renewable fuels [4].
Organizations and research institutes, for instance the Sustainable Aviation Fuel User
Group and the Institut Francais du Petrole (IFP), are among the pioneer supporters of
alternative jet fuels. The latest goal of International Air Transport Association (IATA) is for its
members to be using a 6% mix of sustainable 2nd generation biofuels by 2020 [5]. On the other
hand, there is an immediate need for investigating the products of combustion of these
alternative aviation fuels. The current research project, as a segment of a larger study conducted
at the Combustion Research Laboratory2, is aimed to fulfill this goal.
2 Department of Mechanical and Industrial Engineering, at the University of Toronto
3
Numerous computational and experimental studies of kerosene-based fuel combustion have
been conducted in jet stirred reactors, shock tubes and flow tubes [6,7]. There are also a few
studies of jet fuel surrogate in non-sooting counterflow flames, such as work done by Humer and
Cooke et al. [8,9]. However, experimental studies of sooting jet fuel flames, i.e. Jet A-1, JP-8 or
any blend of different jet fuels in a laminar coflow flame, are very limited if any exists. Most
coflow flame studies were either done on simple gaseous fuels (such as ethylene (C2H4), methane
(CH4) or non-sooting surrogates) or there was only a trace of jet fuel in the fuel stream [10].
Experimental data, also, can be used to validate models of combustion chemistry and soot
formation. Findings from Jet A-1 and other alternative jet fuels in coflow combustion will lead to
better understanding of species concentration profiles in the flame, thermo-chemical mechanism
of combustion reactions, polycyclic aromatic hydrocarbon (PAH) formation and soot studies.
1.2 Research Objectives
The goal of this research project is to measure gaseous species in different jet fuel coflow
diffusion flames along the centreline, and where possible, several radii. The fuels used in the
current study are divided into two groups of conventional and Fischer-Tropsch (FT) kerosene jet
fuels. For this study, Jet A-1 has been used as a base fuel (i.e. conventional kerosene-based jet
fuel as a reference jet fuel). The experimental FT kerosene fuels include: (1) Gas-to-Liquid
(GTL), (2) Coal-to-Liquid (CTL), and (3) a blend of 80 vol.% GTL and 20 vol.% hexanol jet
fuels (Hex20-GTL). The final goal may be divided into the following specific three objectives:
4
• to develop a robust technique to obtain a stable flame for these complex liquid fuels;
• to sample gases in the most accurate manner to avoid any sample loss and minimize the
flame disturbance;
• to measure and interpret the concentration of major species in the flames.
1.3 Research Execution
The Jet A-1 was obtained from National Research Council Canada-Institute for Aerospace
Research (NRC-IAR), Gas Turbine Laboratory. The alternative fuels were provided through the
ALFA-BIRD international collaborative program between University of Toronto and research
institutes and companies in European Union and South Africa.
Flame studies were carried out at atmospheric pressure in a coflow diffusion flame. Gas
samples from the flame were analyzed using a number of experimental techniques. Hydrocarbon
concentrations were obtained by gas chromatography (GC) equipped with flame ionization
detectors (GC-FID). The carbon monoxide (CO) and CO2 concentrations were measured using
thermal conductivity detector gas chromatography (GC-TCD). A non-dispersive infrared
(NDIR) spectroscope was used to measure CO and CO2 concentrations in real-time. Details of
experimental apparatus and analytical methodology are described in Chapter 3. The experimental
species concentrations for Jet A-1 flame were compared with the numerical results of Saffaripour
et al. [11].
5
Chapter 2
2. Background Research
The gas turbine engine, also commonly known as the jet engine, is derived from the steam
turbine adapted to a different working fluid. Since 1937 when Whittle’s prototype jet engine
used kerosene as fuel [12], the gas turbines has been tailored to utilize a wide variety of
combustible gases and liquids, including crude oil. An aircraft propulsion unit, however, only
accepts certain liquid distillates which meets certain criteria such as ASTM D1655.
2.1 Aviation Fuels
Because the jet aircraft is a weight-limited vehicle, hydrocarbon fuels with high gravimetric heat
content (i.e. high hydrogen-to-carbon ratio) are desired for aviation [13]. On the other hand,
some fuels with highest gravimetric energy content but low density, such as hydrogen and
methane, have low volumetric energy content and hence take large storage space. Among HC
fuels, paraffinic ones meet this requirement. They have high mass heat contents, while their
density is less than non-paraffinic fuels.
Conventional paraffinic jet fuels can be divided into two main categories: civilian (e.g. Jet B,
Jet A or Jet A-1) and military (e.g. JP-4 or JP-8) grade aviation fuels. The JP-4 fuel, which is a
wide-cut from distillate, was used mainly by US Air Force after World War II due to scarcity of
6
kerosene. Nowadays, US Air Forced has changed back to a kerosene-based jet fuel (JP-8) owing
to the disadvantages of a wide-cut fuel, for example its high volatility. Kerosene-based Jet A and
Jet A-1 are predominant civil aviation fuels. Jet A is mainly used in United States while most of
rest of countries, including Canada, use Jet A-1. The Jet A-1 has a lower maximum freezing
point than Jet A (-47 ºC for Jet A-1 versus -40 ºC for Jet A). Jet B, however, is still used in some
parts of Canada and Alaska because it is suited to cold climates [13,14]. Detailed specifications
of these fuels are described in the following section. For the purpose of this study, Jet A-1 has
been used to represent conventional jet fuel.
2.1.1 Physical and Chemical Properties
Fuel properties are mainly determined by the nature of the crude oil from which they are derived.
Some properties such as volatility (e.g. flash point and flammability) affect safety; whereas some
deal with fluidity (e.g. viscosity and freezing point). Aromatics composition likewise plays an
important role because of its effects on combustion. Aromatics cause greater elastomer swell
compared to aliphatic HC’s or other fuel constituents. A minimum amount of aromatics
concentration is required to improve sealing properties of fuel. Needless to say, the excess of
aromatic content links to degradation of elastomeric parts [15]. Sulphur content, along with
aromatics content is of a great importance due to health concerns that arise from their emissions
upon combustion. However, sulphur is necessary for fuel lubricity. Aromatics and sulphur
content may not exceed 25 vol.% and 0.3 wt.%, respectively. In the case of civil aviation fuel, for
7
aromatics above 20 vol.% [13] users must be notified. The aromatics content should not drop
below 8 vol.% [16]. The Jet A-1 used for this experiment contains 18.9 vol.% aromatics and
0.0577 wt% sulphur, determined by ASTM D 1319 and 4294 methods, respectively. Selected
specification properties of typical civil and military aviation fuels, along with Jet A-1 used for this
experiment are listed in Table 2.1. The information on the experimented Jet A-1 included in this
table, was provided by Shell Canada Ltd. (jet fuel supplier to NRC-IAR). These properties were
measured by standard ASTM methods included in square brackets in front of each property. The
fuel composition (refer to Table 3-1 and Appendix A for more detailed composition analyses)
and smoke point analysis on Jet A-1 was done by Alberta Research Council (ARC).
Table 2-1: Specific properties of aviation fuels [13] including the experimented Jet A-1
Characteristics [ASTM Test Method] Jet A JP-4 JP-8 Jet A-1
Flash point, (ºC) mina [D56] >38 >60 >38 40
Density @15 ºC (kg/m3) [D 4052] 775 – 840 751 – 802 775 – 840 807
Freezing point, (ºC) maxa [D 2386] -40 -58 -47 -53
Viscosity @-20 ºC, (cSt) maxa [D 445] <8.0 <8.5 <8.0 4
Smoke point, (mm) mina [D 1322] >26 >20 >19 21
a Limits for typical fuel except for Jet A-1 which has the exact value
8
Heat of combustion, the most important characteristic property of any fuel, for all these fuels
is above 42.8 MJ/kg. According to the information provided by Shell Canada on the
experimented Jet A-1, the estimated net heat of combustion (ASTM D 4529) for this fuel was
43.2 MJ/kg. Some of the fundamental properties of jet fuels are mentioned above. In addition,
some of the other significant properties are as follow:
Stability (ASTM D 3242)
A stable fuel is one whose properties remain unchanged through time (storage stability) and at
elevated temperature in the engine (thermal stability) [17].
Lubricity (ASTM D 5001)
Lubricity is a measure of liquid fuel’s effectiveness as a lubricant for reducing the friction between
solid surfaces in engine during relative motion. Jet fuel must possess a certain level of lubricity.
Volatility (ASTM D 5190 and 5191)
Volatility is important because a fuel must be vaporized before it burns. However, too high of a
volatility can result in evaporative losses.
Other properties such as non-corrosivity (ASTM D 130), cleanness (absence of water
(ASTM D 3240) and solids in fuel (ASTM D 5452)), and resistance against microbial growth in
fuel (ASTM D 6469) are also significant factors for fuels to be certified as aviation fuels
worldwide.
9
2.1.2 Proposed Alternative Jet Fuels
One of the suggested solutions in the effort to reduce the levels of GHG emissions, which has
attracted particular attention, is alternative fuels for aircrafts. According to the Air
Transportation Association (ATA), fuel is an airliner’s second largest expense. Historically, fuel
expenses have ranged from 10% – 15% of each US airline passengers’ cost, while recently it
reached as high as 35% in the third quarter of 2008 when oil prices peaked in July of that year
[18]. Fuel price instability can be detrimental to the airline industry. Alternative sources of jet
fuel might increase the price stability. However, not every alternative fuel can be employed due to
constraints specific to the use of aircraft. Sections 2.1.2.1 to 2.1.2.4 review a number of most
promising options, many of which have been experimented in this research.
2.1.2.1 Fischer-Tropsch Synthetic Kerosene
Gas-to-Liquid Process
Various carboniferous feedstocks can be converted to synthetic paraffinic kerosene (SPK)
through different synthetic fuel production processes, such as the Fischer-Tropsch (FT) process.
Fischer-Tropsch fuels are typically manufactured in a three-step process:
1) Syngas generation
The feedstock (e.g. coal, biomass or natural gas) is converted into synthetic gases (syngas) in a
few steps depending on the type of feedstock. Synthesis gas mainly consists of CO and H2.
10
2) Hydrocarbon synthesis
The syngases are catalytically converted into a mixture of C1-C40 liquid HC’s, producing
“synthetic crude”. This step is the actual FT synthesis. The general reaction dominating FT
process is,
�2n+1� H2+n COcatalyst (e.g. Ni, Co, Fe)���������������� CnH�2n+2�+n H2O �2.1�
This crude is then sent to distillation columns to separate different cuts.
3) Upgrading
The mixture of FT hydrocarbons from the distillation columns is then upgraded through
hydrotreating, hydrocracking and isomerization and finally fractionated into the desired fuels.
Natural gas (NG) is one type of feedstock for FT process. After separating methane from
the NG and mixing it with oxygen at 1,400 ºC – 1,600 ºC in a reformer, the produced syngases
undergo low-temperature FT process to produce Gas-to-Liquid (GTL) kerosene along with
liquefied petroleum gas (LPG), naphtha, diesel and base oils. Figure 2.1 summarizes the main
steps in a GTL process. Shell Ltd. has the world’s largest GTL production plant under
construction in Qatar (Pearl Project). Shell GTL Jet Fuel, also known as FT-SPK, was approved
for use in civil aviation in late September 2009 [19].
11
Figure 2.1: Simplified block diagram of GTL process to produce FT-SPK
The GTL kerosene is virtually sulphur- and aromatics-free. The GTL fuel mainly contains
normal (n-) and iso-paraffinics and a few (~8 wt.%) 2-cycle naphthenes [20]. On one hand, this
composition makes it an attractive option from environmental point of view. On the other hand,
this advantage results in poor lubricity and sealing properties. The low levels of aromatics in
GTL fuel can be overcome by the introduction of small quantities of additives and aromatics (or
naphthenic cut) to bring the level of these compounds in GTL fuel to the specification limits of
ASTM D 7566 standard criteria for new aviation fuel.
Coal-to-Liquid Process
A coal-to-Liquid (CTL) process shares many similarities with the GTL process, yet has
distinguished additional streams, shown in Figure 2.2, which add aromatics in the form of
naphthenic compounds to the final FT products. This process was initially developed by Nazi
Germany during World War II to produce fuels from coal. The CTL process was then further
developed by a South African oil company, Sasol, to produce kerosene type fully synthetic jet fuel
(FSJF). The terms of CTL jet fuel and FSJF have been used interchangeably in this report.
FT-SPK Upgrading
Heat
Pressure
NG Syngas Reforming
Heat
Pressure
+ O2
Low-Temperature
Fischer-Tropsch n-&i-Paraffinics
12
Figure 2.2: Simplified block diagram of Sasol CTL process to produce FSJF3
In this process, syngases are produced from coal in gasifiers, and then undergone a high-
temperature FT process to produce iso-paraffinic kerosene along with LPG, gasoline, diesel and
chemicals. The “coal tar” is a high viscose liquid left after gasification of coal and contains
complex mixture of phenols, PAHs and heterocyclic compounds. Light distillate and heavy
naphtha are produced by hydrocracking and hydrotreating the coal tar. These products are then
blended with i-paraffinic kerosene to produce FSJF [21]. As of April 2008, Sasol achieved
approval for 100% synthetic jet fuel for international use in commercial aviation [22]. Similar to
FT-SPK, the FSJF is sulphur-free. The CTL kerosene, however, has about 48.5 wt.%
naphthenes and 10.0 wt.% aromatics [20]. A more detailed GTL and CTL fuel composition
analyses are presented in Section 3.1.
3 Adapted and modified from Sasol Synfuels International (refer to [21])
Heat
Pressure
Heat
Pressure
+ Steam
Upgrading Coal Syngas Gasification High-Temperature
Fischer-Tropsch
FSJF
Distillate
Naphtha
Light Distillate
Heavy Naphtha Hydrotreating
Hydrocracking Arom.
Naph.
Coal T
ar
i-Paraffinics
13
2.1.2.2 Bio-Derived Synthetic Paraffinic Kerosene (or BTL)
The SPK can be derived from biomass feedstock (energy crops), such as switchgrass and napier
or woody biomass. Pyrolysis products from biomass feedstock can be then gasified to produce
syngas. The syngas products from gasification will then undergo FT process analogous to what
was described in the previous section. Bio-SPK benefits from diverse carbon-based input.
Gasification followed by FT process is capable of producing straight-chain molecules of variable
lengths, which can be then refined to obtain Bio-SPK. The product of FT process varies
depending on the catalyst, temperature and the pressure of the process. In other words, Bio-SPK
is a form of Biomass-to-Liquid (BTL) fuel. Bio-derived fuel (or any BTL) has this advantage
over CTL and GTL to be a relatively carbon neutral process. A simplified diagram of Bio-SPK
production is shown in Figure 2.3.
Figure 2.3: Simplified block diagram of thermochemical conversion route for Bio-SPK4
4 Adapted from IATA 2009 Report on Alternative Jet Fuel
CO2
Ash
Volatiles
Bio-SPK Biomass
Feedstock
Char, Volatile,
and Bio-oil Syngas Gasification Fischer-Tropsch Pyrolysis
Heat
Pressure
Heat
Pressure
+ Steam
Heat
Pressure
14
2.1.2.3 Bio-Alcohols
Bio-alcohols can be produced via fermentation of sugar, starch or lignocellulosic biomass.
Alcohols, in particular methanol and ethanol, have low heating content. The longer the carbon
chain, the higher the heating content of that alcohol would be. Low specific gravity and flash
point of both ethanol and methanol add to their impracticality as jet fuel. Nevertheless, higher
and/or branched alcohols, such as hexanol or iso-butanol, meet these specifications with a much
closer margin to common jet fuels. Table 2-2 compares some of these key properties.
Table 2-2: Comparison between key thermochemical and physical properties of Shell Jet A-1,
ethanol and hexanol
Property Jet A-1 Ethanol Hexanol
Energy Content (MJ/kg) 42.8 28.9 39.1
Flash point, (ºC) 40 9 59
Density @15 ºC (kg/m3) 807 789 814
Viscosity @-20 ºC, (cSt) 4.0 1.5 3.6
Boiling point, (ºC) 151- 270 78 157
15
There is ongoing research for developing production process of higher alcohols such as
butanol [23,24] and hexanol [25] on a commercial scale. The water solubility in alcohol,
however, poses a contamination issue. Based on the above, a higher alcohol combined with
kerosene is been recommended as a fuel. A blend of 80 vol.% GTL and 20 vol.% hexanol
(Hex20-GTL) was tested in the current study.
2.1.2.4 Other Blends
In order to avoid compromise of kerosene performance in jet engines, a blend of suggested
alternative fuels with mineral kerosene is advised. Together with the proposed blends mentioned
above (20 vol.% hexanol + 80 vol.% GTL), a fuel mixture of 50 vol.% naphthenic cut with GTL
kerosene was suggested by ALFA-BIRD program for examination as alternative jet fuel.
Naphthenic compounds are derived by liquefaction of coal or biomass [26]. Due to time
constraints, this fuel was left out of the scope of this research.
2.1.3 Surrogate of Jet Fuels
Jet fuel consists of hundreds of species, many of which are unidentified [refer to Appendix A for
complete analysis of Jet A-1 composition]. Surrogate fuel is defined as a simpler fuel which can
represent the combustion characteristics of an actual fuel. In terms of modeling the combustion
of complex fuels (e.g. jet fuel), it is suggested to use a surrogate fuel instead of a real fuel. Dagaut
et al. [27] used a surrogate mixture of 69% n-decane, 20% n-propylbenzene and 11% n-propyl-
16
cyclohexane (by mole) in their model which well-represented the combustion of Jet A-1 in a jet
stirred reactor. The surrogates for alternative jet fuels are listed [28] in Table 2-3.
Table 2-3: Surrogates for alternative jet fuels suggested by Dagaut [28]
Jet fuel Surrogate (mol %)
GTL (C9.81H21.62) 90.6% n-decane + 9.4% i-octane
CTL (C9.59H19.98) 72% n-decane + 13% i-octane + 15% propylbenzene
Hex20-GTL (C8.76H19.53O0.275) 65.7% n-decane + 6.8% i-octane + 27.5% hexanol
50 vol.% GTL + 50% naphthenics 45.3% n-decane + 4.7% i-octane + 50% propylcyclohexane
2.2 Jet Engine Design
While there are variations, every jet engine shares basic core components: a compressor, a
combustor, and a turbine. In a jet engine, air is compressed in series of stages, fuel is burned
continuously in compressed air and then the hot gas is expanded through a turbine. The turbine
extracts energy to run the compressor and also provides shaft power. The ejection of hot air from
back of the engine provides thrust in the opposite direction. The exhaust is composed of CO2
and water vapour. However, high concentrations of CO, PAH and PM emissions are expected
during takeoff [29].
17
Figure 2.4: A typical jet engine drawing showing the three main steps: compression, combustion,
expansion5
Since the adaptation of the modern gas turbine concept to aircraft in the early 20th century,
advance modifications have been done to jet engines to improve fuel efficiency. Enhancements in
aircraft design, airline operation, airspace and airport capacity have provided about 30% to 35%
improvement in fuel efficiency [1]. However, there is a boundary to technological advances in
engine design and its efficiency can be improved to a limited extent in the future.
2.2.1 Emissions
Complete combustion of hydrocarbons leads to the production of CO2 and water. Due to
presence of sulphur in jet fuel, formation of SO2 is also possible. Other significant emissions
5 Source: http://commons.wikimedia.org
Intake Compression Combustion Exhaust
Air Inlet Combustion Chambers Turbine
Cold Section Hot Section
18
include CO, unburned hydrocarbon and PM which are the results of incomplete combustion,
engine design, operating conditions and/or combination of all.
Carbon dioxide is a primary GHG. Carbon monoxide, on the other hand, is highly toxic.
Sulphur oxides (mainly SO2) are known to contribute to the formation of aerosols and
particulates. These compounds are also serious respiratory health hazards, especially for children
[30]. With regards to NOX emissions, there are two sources for NOX formation in engine: (1)
from the oxidation of atmospheric nitrogen (N2) at very high temperatures found in the
combustor (thermal NOX), and (2) from fuel bound nitrogen, which in trace amount improves the
lubricity of fuel. NOX emissions are considered as central contributors in the formation of ozone
near ground level [31].
2.3 Fundamentals of Coflow Laminar Diffusion Flame
Fuel combustion is a complex process; the understanding of which requires knowledge of fuel
chemistry, thermodynamics, mass and heat transfer, reaction kinetics and fluid dynamics of the
process. A diffusion flame is a flame in which fuel and oxidant are separately introduced and the
rate of fuel consumption is determined by the diffusion rate. Examples of diffusion flames are the
candle flame, gaseous fuel jets and the Bunsen-burner flame [32].
19
Coflow flame is a conical multi-dimensional flame. Coflow flame studies have also been
used to shed light on how soot is formed in diffusion burning, for example works done by
Santoro et al. [33,34,35] and others [36,37].
Although the coflow laminar flame study appears to be far from the reality of the turbulent
phenomena happening in a jet engine at high pressures, this study is essential to fully understand
the combustion of jet fuels in any condition in detail. Turbulent combustion is far from being
fully understood. “Since the flow is turbulent in nearly all engineering applications, the urgent
need to resolve engineering problems has led to preliminary solutions called turbulence models”
[38]. Turbulent models stem from equations governing laminar flames. In both laminar and
turbulent flames, the same physical processes are applied and many turbulent flame theories are
based on underlying laminar flame structure [39]. Because measuring gaseous species in a
turbulent flame, especially in sooting flames such as jet fuel flames, is difficult, the study of
gaseous species in laminar flames is necessary to understand and validate combustion models. A
coflow laminar flame, however, gives a steady, relatively simple axisymmetric flow field and thus
makes the understanding of the flow field amenable. Knowledge of the concepts developed and
results obtained from laminar flame is a necessary prerequisite to the study of turbulent flames
[39]. This research also couples with a numerical study (refer to [11]).
20
2.3.1 Governing Equations for Laminar Diffusion Flame
Chemically reacting flow problems, such as the laminar diffusion flame are mathematically
formulated using equations for species and mass continuity, momentum and conservation of
energy. This problem is considered at a steady flow for a two-dimensional axisymmetric (r- and z-
coordinates) geometry. These series of derived equations are shown in Appendix D.
2.3.2 Flame Liftoff
The distance from the base of a detached flame to its fuel nozzle is called liftoff. A minimum
liftoff is desired to avoid heat conduction back to the burner through the fuel nozzle. In order to
avoid partial premixing, a flame liftoff should not exceed a specific height. When the flame
approaches the maximum liftoff, inhomogeneous fuel-air premixing occurs [40]. If an optimal
size of liftoff is attained, appropriate simplification can be applied to the flame’s thermal
boundary conditions. This eases and accelerates the modeling process of the flame. Further liftoff
adds to turbulence or even causes blow-off.
2.3.3 Flame Length (or Visible Flame Height)
The most common definition of flame length is the distance from the tip of the fuel nozzle (or
the burner, if they are equally levelled) to the position on the flame centreline where the fuel and
oxidizer are in a stoichiometric ratio. Based on Roper analysis for a circular fuel port [39], the
21
flame length is independent of initial velocity (fuel velocity leaving the port) or diameter
exclusively, but proportional to initial volumetric flowrate, QF.
ℒ� ≈ 38�
�������,�����
�2.2�
Here, YF, stoic is the stoichiometric mass fraction of fuel. In highly diluted system, QF is mainly
driven by diluent flowrate.
In 1928, Burke and Schumann developed set of complex equations to calculate the flame
height theoretically. Since then, several studies were done to improve the accuracy of Burke-
Schumann equations by including, for instance, buoyancy and more reasonable assumptions [41].
For the purpose of this study, however, estimating the flame height visually was found
sufficiently indicative.
22
2.4 Soot Formation in Coflow Flames
The term soot refers to nano-meter sized carbonaceous particles produced as a result of HC fuel
combustion. Numerous studies have been conducted on the hazardous effects of soot emission
on the environment and the human respiratory system. Besides direct health effects of
combustion-generated soot, the temperature decrease due to radiant heat losses from soot affects
flame length and other temperature dependent processes, such as NOX formation in engine [36].
The formation and destruction of soot is a notable feature of non-premixed flames.
Carbon molecules emit a yellow-orange light when heated. This phenomenon is called soot
luminosity. Thus, a yellow flame indicates a sooting flame, while a blue flame does not contain
soot. Considering the complex chemistry and physics of soot formation, Turns [39] has
suggested that soot formation essentially proceeds in a four-step sequence:
1) Formation of precursor species,
2) Particle inception,
3) Surface growth and particle agglomeration, and
4) Particle oxidation.
The location of these steps is shown on the next page.
23
Figure 2.5: Soot formation and destruction zones in laminar diffusion flames [39]
Initially, the fuel breaks down to ethylene, acetylene and other active reactants [42]. In the
first step, molecular precursors are formed, which are thought to be heavy polycyclic aromatic
hydrocarbons (PAH). Chemical kinetics play an important role in this step. The growth route
from small ring molecules (e.g. benzene) to larger molecules and then PAH’s appear to involve
both addition of C2 (in particular acetylene), C3 or other HC chains to PAH radicals and
reactions among growing aromatic groups (such as PAH – PAH radical combination) [43]. One
of the main paths of PAH formation is the process of H-abstraction C-addition, also known as
HACA growth [44]. In this process, C2H2 molecules substitute hydrogen radicals on benzene
and form larger aromatic molecules. The principle of HACA mechanism is shown in Figure 2.6.
Majority of acetylene molecules in a flame are produced from ethylene β-scission.
Soot oxidation zone
Soot particle
growth zone
Soot particle inception
(nucleation) zone
z
r
24
Figure 2.6: The H-abstraction–C2H2-addition (HACA) mechanism of PAH formation [44]
The soot formation is indeed more prominent for fuels that contain benzene and
naphthalene than aliphatic fuels (paraffins, mono- and di-olefins). In the second step, heavy
PAH molecules form nascent soot particles with a molecular mass of approximately 2000 amu
and an effective diameter of about 1.5 nm. After the formation of the nascent soot particles, their
mass is increased by the addition of gas phase species such as C2H2 and PAH. This follows by
sticking collision between smaller particles during mass growth. Consequently, the number of
particles at this stage decreases while the total mass remains unchanged. At higher residence time
(in the post-flame regime), the initially amorphous soot converts to a more graphite carbon
material. Finally, during the oxidation step, PAH molecules and soot particles both form and
25
oxidize. Oxidation always happens at the flame tip and “wings” since the soot is always formed
interior to the flame sheet lower in the flame and the flow streamlines, which soot particles
follow, do not cross the reaction (oxidation) zone until near the flame tip [39]. A rough picture
of these steps is shown in Figure 2.7.
Figure 2.7: A rough picture of soot formation6 [43]
6 Special thanks to Rémi Cordonnier, a visiting student from France, who helped me with this drawing.
CO
CO2
O2
OH2
H2
50 nm
Coagulation
Surface Growth
Particle Inception
Zone
Reaction Time
0.5 nm
Molecular Zone
26
The formation of soot in diffusion flames can be reduced if the flame length is shortened.
Many studies have proved that fuel dilution with inert gases such as nitrogen reduces the amount
of soot [45]. Flame temperature and more importantly, the temperature field created by the
flame, influences the flame tendency to form soot considerably [42]. According to Milliken, the
cooler the flame is, the greater the tendency to soot would be [46].
Effect of Oxygen Content of Oxidizer
In coflow diffusion flames, altering the nitrogen to oxygen (O2) ratio in the oxidizer stream
changes the temperature and consequently, the soot tendency. The amount of oxygen in the
oxidizer has a strong influence on the flame length and liftoff. A small reduction in O2 content of
oxidizer stream results in longer flames and larger liftoff.
Wings
The term “wings” refers to the furthest point from centreline on the flame sheet (reactant sheet).
Smoke & Smoke Point
If some of the soot that is formed does not oxidize on its path through high-temperature
oxidizing region, soot wings may appear with the soot breaking through the flame. The soot that
breaks through is referred as smoke. Whether or not all the soot oxidizes while passing through
the oxidation zone, depends on the fuel type and flame residence time.
27
According to the American Society for Testing and Materials (ASTM), the smoke point of
aviation turbine fuel is “the maximum height, in millimetres, of a smokeless flame of fuel burned
in a wick-fed lamp of specified design”. The higher the smoke point is, the less sooting the fuel
would be. Smoke points for Jet A-1 and other fuels proposed by ALFA-BIRD program have
been analyzed by ARC using the ASTM D 1322 method. The results are shown in Table 2-4.
Table 2-4: Smoke point analysis of experimented jet fuel
Sample Type Smoke Point (mm)
Shell Jet A-1 21.5
Shell GTL >50
Sasol CTL 22.0
Shell GTL 80% + Hexanol 20% >50
Shell GTL 50% + Naphthenic Cut 50% a 29.0
a This fuel was not used for this study
If N2 or any inert gas is added to the fuel jet when the flame smokes, the luminous zone closes
and soot no longer emanates from the top of the flame [42]. If fuel flowrate increases, further
dilution is require to suppress smoking. According to Equation (2.2), diluting the fuel with an
inert gas also has an increasing effect on the flame length by decreasing the stoichiometric ratio
and increasing the QF.
28
Chapter 3
3. Experimental Apparatus & Analytical Methodology
The experimental setup and analytical technique for the present study are explained in detail in
this chapter. Figure 3.1 illustrates a schematic diagram of the experimental setup. This setup was
aimed to address four different areas of interest in any coflow flame study: (1) gaseous species
analyses (scope of current research), (2) PAH measurements, (3) temperature measurement, and
(4) soot concentration and morphological properties evaluation. The process of developing this
setup can be classified to two main categories: (1) tasks that were involved with getting a stable
coflow flame from liquid fuels, (2) sections dedicated to collecting and analyzing of samples from
flames. The setup consisted of a fuel delivery system combined with a vaporizer, a coflow
diffusion flame burner, a gas sample collection system and a number of analytical equipment, all
of which were connected by heated transfer lines. Once a stable flame was achieved, gaseous
samples were continuously withdrawn from the flame to be analyzed onsite and were pumped
first to a GC-FID, and second to a GC-TCD.
30
3.1 Fuel Supply
Jet fuels tested for this study were: (1) Jet A-1, (2) Shell GTL jet fuel, (3) Sasol CTL jet fuel,
and (4) a blend of 20% hexanol and 80% GTL by volume (Hex20-GTL) jet fuel. Knowing the
fuel chemistry is an asset for better realization of the fuel combustion. Hence, samples of Jet A-1
were sent to ARC for Hydrocarbon Group Type (ASTM 1319), Supercritical Fluid
Chromatography (CGB 3.0 No. 15.0) and Hydrocarbon Components (CGB 3.0 No. 14.3)
analyses. Since typical jet fuel is a cut from crude oil distillate, it contains countless of species.
More than 72 wt.% of species in Jet A-1 were identified in the report by ARC. The detailed
chemical analysis of Jet A-1 is attached as Appendix A. Table 3-1 on the following page
highlights some of the important compounds in this analysis. It is noticeable that n-decane had
the highest concentration and no oxygenates were found.
In addition to the Jet A-1 composition analysis, smoke points7 (refer to Table 2-4), constant
pressure specific heat capacity (CP) and thermal conductivity (k) of all fuels were evaluated8. The
thermophysical properties of jet fuels, CP and k, are necessary to calculate the actual fuel
flowrates, as discussed later in Section 3.2. Table 3-2 lists specific heat capacity and thermal
conductivity of all jet fuels available to Combustion Research Group.
7 Analysis performed by ARC
8 CP and k were determined by “Thermophysical Properties Research Laboratory, Inc.”, West Lafayette, IN
31
Table 3-1: Summary of Jet A-1 composition analysis by group and carbon number
Group C # wt.% vol.% mol.% Group C # wt.% vol.% mol.%
Aromatics C7 0.088 0.083 0.138 Olefins C8 0.224 0.256 0.289
C8 1.465 1.376 1.994 C9 1.341 1.495 1.536
C9 6.064 5.640 7.301 C10 0.607 0.670 0.626
C10 7.656 7.003 8.297 Total: 2.173 2.420 2.450
C11 8.873 8.038 8.764 n-Paraffinics C7 0.043 0.051 0.062
C12 3.512 3.267 3.125 C8 0.504 0.586 0.638
Total: 27.658 25.407 29.618 C9 2.558 2.908 2.882
i-Paraffinics C8 0.238 0.275 0.301 C10 5.041 5.639 5.121
C9 2.262 2.549 2.549 C11 4.720 5.208 4.365
C10 5.540 6.146 5.628 C12 3.798 4.140 3.223
C11 4.566 4.838 4.222 C13 3.061 3.306 2.400
C12 1.167 1.259 0.991 C14 1.722 1.842 1.254
Total: 13.774 15.067 13.690 C15 0.424 0.448 0.288
Naphthenics C7 0.139 0.148 0.205 C16 0.103 0.109 0.066
C8 0.872 0.916 1.124 Total: 21.974 24.237 20.299
C9 2.239 2.287 2.563 Unidentified N/A 27.868 26.202 26.646
C10 3.303 3.316 3.404
Total: 6.553 6.667 7.295
32
Table 3-2: Specific heat capacity and thermal conductivity of experimental fuels9
Sample Type Heat Capacity
CP (J/gK)
Thermal Conductivity
k (W/mK)
Shell Jet A-1 1.91 0.137
Shell GTL 2.13 0.148
Sasol CTL 1.95 0.135
Shell GTL 80% +
Hexanol 20% 2.35 0.146
Shell GTL 50% +
Naphthenic Cut 50% 2.00 0.130
Specific heat capacity and thermal conductivity were measured using ASTM E-1269 and ASTM
D-5334 methods, respectively.
The detailed fuel analyses for GTL and CTL fuels were obtained from the latest report of
Institut Francais du Petrole in the ALFA-BIRD meeting in July 2010 [20]. The detailed fuel
characterizations were carried out by implementing various analytical techniques; namely, gas
chromatography, mass spectroscopy and two-dimensional gas chromatography. The estimated
molecular formulas for GTL and CTL were suggested to be C10.08H21.97 and C11.38H21.04,
respectively. Note that these estimated molecular formulas for these fuels are slightly different
from the ones suggested by Daguat for surrogates (refer to Table 2-3).
9 measured at 23 ºC
33
Figure 3.2: Comparison between main HC groups composition in GTL and CTL fuels
3.2 Fuel Vaporization System
Kerosene fuels are complex mixtures of HC’s with relatively high boiling points, ranging between
145 – 300 ºC. Vaporization of heavy multi-component liquid fuels, such as the fuels for the
current study, is a significant challenge. To overcome this challenge, liquid fuels were highly
diluted with nitrogen (carrier gas) and vaporized in a unique vaporization system. The nitrogen
addition not only assists the vaporization process, but also reduces the overall amount of soot.
0
5
10
15
20
25
C9 C10 C11 C12 C13 C14 C15
wt. %
C #
i-Paraffinics
CTL
GTL
0
2
4
6
8
10
12
14
C9 C10 C11 C12 C13 C14 C15
wt. %
C #
n-Paraffinics
CTL
GTL
0
0.5
1
1.5
2
2.5
C7 C8 C9 C10 C11 C12 C13 C14 C15
wt. %
C #
AromaticsCTL
GTL
0
2
4
6
8
10
C9 C10 C11 C12 C13 C14 C15 C16 C17 C18
wt. %
C #
NaphthenicsCTL
GTL
34
A Bronkhorst® Controlled Evaporator Mixer (CEM) unit10 served as the fuel delivery
system. This unit consists of a temperature-controlled vaporizer chamber, a liquid mass flow
meter with control function (LIQUI-FLOW), and a gas mass flow controller (EL-FLOW).
The temperature of CEM and mass flows were controlled by a digital readout11. The maximum
capacity of this unit is 20 g/h of liquid (fuel) and 2 L/min of carrier gas (N2) flowrates. The
CEM temperature can reach up to 200 ºC. The N2 should be supplied at inlet gauge pressures
between 235 – 305 kPa (max. 163 kPa higher than outlet pressure). The inlet gauge pressure of
liquid mass flow controller must sustain at 295 kPa. In order to maintain this pressure, fuel was
pressurized by N2 (inert gas) in a Millipore12 pressurized tank. The solubility of N2 in HC liquids
similar to jet fuels (such as n-decane and n-dodecane) was reviewed [47,48]. Henry’s Law was
not applicable at this moderately low pressure. Thus, N2 solubility in fuel was negligible. The
liquid flow meter was calibrated by the manufacture for n-tetradecane (C14H30). The flow
properties of C14H30 match with those of jet fuel to a good extent. Nonetheless, Hoskin
Scientific, the vender of CEM unit, agreed to calculate the actual liquid flowrate for any fuel,
using the four fuel properties of CP, k, � and �. The liquid mass flow meter/controller was set to
values (on C14H30 basis) which corresponded to equal mass flowrates for all the fuels (i.e.
10 W-102A-NN0-K (midsize) model
11 E-7120 model
12 1 US Gallon size
35
�� �� ! " = �� �� ! $) (see Table 3-3 on Page 39). Gas and liquid streams were mixed in a mixing
device, which includes an atomizer and a control valve, before entering the heat exchanger. The
following drawing of vaporizer setup, elaborates how the CEM units communicate and function.
Figure 3.3: Bronkhorst® liquid delivery system with vapour control
The flow sensor assembled on the top of the control valve commends the valve to maintain the
liquid flow at the setpoint value, regardless of pressure change in the mixing device. This fine-
tuned control provides an accurate liquid flow which results in a uniform vapour mixture. The
desired flow and temperature values were set by the digital readout and control system power
supplier. Temperature and flowrate setpoints were specified on the digital readout power supply.
Control Valve
To Digital
Readout Box
Controlled
Evaporator
Mixer
Atomizer
Heated
Liquid Flow Meter Gas Flow Controller
36
In order to prevent fuel condensation, vapourized fuel/N2 mixture was transferred from the
CEM vaporizer to the burner via a 1.8 m long heated transfer line13.
3.3 Coflow Diffusion Flame Burner
Coflow diffusion flames, which are radially symmetric 2-D flames, offer a great deal of
information about the combustion of sooting flames in a more realistic environment. In the
present study, a coannular burner was utilized in which different jet fuels were burned in a
mixture of air and oxygen under atmospheric pressure condition. The drawings of the coflow
burner and its section cut are shown in Figure 3.4 below.
Figure 3.4: Schematic diagram and section cut of a coflow burner (Ox: Oxidizer)
13 Custom design by Unique Heated Products Instrument Grade Heating Sample Line
Fuel + N2 mixture
Ox
Glass beads
Metal foam
Ox
Ox
Ox
37
The burner is comprised of a 10.9 mm ID steel fuel nozzle (12.7 mm OD) surrounded by an
88 mm ID (100 mm OD) outer air passage. The thickness of burner’s wall is 6 mm. Before
exiting the nozzle, the oxidizer passes through a packed bed of 5 mm diameter glass beads and a
porous metal disk to provide a uniform laminar oxidizer flow and enhance flame stability. To
avoid vapour fuel condensation along the fuel tube, the bottom part of the fuel tube was heated
using Omega heating tapes14 and the top part using thin flexible Minco heaters. The fuel nozzle
was long enough to assure a fully developed fuel/N2 mixture flow. The flame was enclosed in a
30 cm clear cylindrical Plexiglas® to protect the flame from laboratory air movement. A narrow
vertical slot was machined in the chimney to provide access for gas sampling. A 10 cm long
ceramic honey comb was mounted at the exhaust of the chimney to straighten the flow exiting
the chimney. The flow straightener enhances the flame stability dramatically. There are four
equally spaced air inlet port located at the bottom of the burner.
3.3.1 What is a Suitable Flame?
A suitable flame in this study is defined as a stable flame with the desired flame length (min.
of 5 – 6 cm), liftoff (max. ~2 mm), and proper soot concentration. Since the fuel mixture was
highly diluted with N2, the fuel jet velocity was mainly determined by the flow of diluent N2. On
the other hand, stabilization of a lifted flame is very sensitive to the coflow air [40,49]. Hence,
14 Omega® Heavy Insulated Heating Tapes (STH series), 156 W
38
different air/fuel/N2 flowrate ratios were examined to find the most “suitable” flame. It was
concluded that the addition of a small amount of O2 to the oxidizer stream is crucial in achieving
the desired flame. The addition of O2 is critical in lowering the flame liftoff and it also changes
soot luminosity, as discussed in Section 2.4.
There are two main limitations on choosing the fuel and nitrogen flowrates and in general,
the fuel/N2 ratio: a) flame height and b) soot concentration.
a) A sufficiently long flame enables a generous number of sampling points, while too long of a
flame results in a flickering flame tip and instability of the whole flame. As shown by the
Equation (2.9), the flame height is highly dependent on the fuel-diluent mixture volumetric
flowrate and fuel mole fraction.
b) The soot concentration in the flame should be such that it allows for gaseous species
sampling without clogging the microprobe, while providing a high enough extinction of the
laser beam for accurate soot volume fraction measurements.
Besides the fuel nozzle, the enriched O2 oxidizer stream was also heated. The hot oxidizer
stream prevented the fuel from forming a cloud of fuel mist after exiting the tip of the fuel nozzle
and also improves flame stability. The oxidizer stream was distributed evenly through a 4-way
manifold within the four coflow air inlets.
39
3.4 Experimental Temperature and Flow Settings
3.4.1 Flow Controls
The optimal nitrogen and fuel flowrates were found to be 710 mL/min and 11.9 g/h,
respectively. As discussed in Section 3.2, the liquid flow meter used C14H30 as the reference
liquid. The conversion factors provided by Hoskin Scientific are listed in Table 3-3. The liquid
flow meter was set based on these factors so that the same mass flowrate of 11.9 g/h was
obtained for all the fuels. The volumetric flowrate of the coflow air was 55.0 L/min. To reduce
the flame liftoff and enhance the flame stability while increasing the nitrogen flow, the oxygen
concentration in oxidizer stream was increased by 25%. A flow of 3.0 L/min of pure oxygen was
added to the air stream which boosted the O2 content from 21% (O2% in air) to 26.5%. All the
volumetric flowrates are at room standard temperature and pressure (21 ºC and 1 atm).
Table 3-3: Fuel flowrate settings on the liquid flow controller in terms of C14H30 fuel flowrates
Fuel Conversion
Factor
Controller Setting
�� (g/h) Actual Fuel Flowrate
�� (g/h) n-tetradecane 1 11.90 11.90
Shell Jet A-1 0.94 11.20 11.90
Shell GTL 1.07 12.69 11.90
Sasol CTL 0.94 11.20 11.90
Shell GTL 80% +
Hexanol 20% 1.17 13.89 11.90
40
The dilution ratio for all the fuels were about 5% by mole of fuel and the remaining was
nitrogen. The sample hand calculations are attached in Appendix E.
The mean velocities of the fuel and oxidizer streams right at the exit were calculated to be
20.34 cm/s and 21.89 cm/s, respectively. The Reynold’s Number15 (Re) based on these velocities
confirmed a laminar flame (%&�� !'() = 48 and %&*�+ = 430)16 for this system.
3.4.2 Temperature Settings
The temperature of CEM vapourizer was set at 190 ºC for all the runs. The oxidizer stream was
heated to 150 ºC before entering the coflow burner. The fuel entrance tube to the burner was
kept to 210 ºC by heating tapes. The heated transfer lines were maintained at about 200 ºC,
while the fuel exit port from the vapourizer was sustained near 170 ºC with heating tapes. This
short vapourizer tube was kept at a lower temperature than other parts to avoid any damage to
the vapourizer. The output power of the heating tapes was controlled by variable voltage
transformers. The last two inches of the fuel tube, above the metal foam, was kept at 200 ºC by
Minco heaters17. The exit fuel temperature was roughly measured at around 180 ºC.
15 %& = ,�-.
16 %& ≤ 2300 is within laminar region 17 Minco heaters output power was manipulated by a DC power supply. The voltage was set to 11 V.
41
3.5 Gas Sampling System
The gas sampling system was designed in an optimal fashion to minimize the disturbance to the
flame and leakage through the transfer lines and all the units. Sampling was conducted by
continuously withdrawing gas from the flame using deactivated fused silica (FS) tubes18, typically
found in GC applications. This new design was developed by former colleague Dr. Sarathy for
collecting samples from non-sooting opposed-flow diffusion flames [50]. Minor adjustments in
its design were taken into consideration to adapt this technique for sampling from a sooting
coflow flame. The probe tips for this design are cheap and easy to replace in case of breakage or
clogging by soot. These qualities exhibit substantial advantages over old fashion quartz
microprobes, as formerly used in several flame studies [51,52]. Samples were pumped by an oil-
free, heated head, diaphragm vacuum pump19 and transferred by heated lines.
3.5.1 Sampling Apparatus
To investigate the flame chemistry accurately, reactions should be quenched at the moment
where gas is sampled. Fristrom [53] argues that rapid temperature drop is not mandatory for a
successful flame sampling. Instead, he explains how reactions halt with a large pressure drop
18 Agilent Deactivated Fused Silica Retention Gap
19 KNF oil-free heated vacuum pump Model N 036 ST. 11E (vacuum side: 24 in. Hg and pressure side: 20 psig)
42
along the probe and the destruction of the free radicals on the probe walls [54]. The discussion is
based on the fact that changes in pressure directly affects total gas density (P ∝ ρ), which is
function of mole (or mass) fraction, as shown in Equations (3.1) and (3.2). If M is used to denote
the concentration of species in a chemical reaction of nth order, the rate of reaction expression is,
2�3�24 = −6�3�7 �3.1�
where M can be written in terms of total density ρ times the mole (or mass) fraction of M, YM (or
XM). Hence, Equation (3.1) can be formulated in the following manner,
82�924 : = −6�97�7;" ∝ <7;" �3.2�
Therefore, for the 2nd order reactions, the reaction rate decreases with a decrease in pressure.
Schoenung and Hanson also showed that CO measurements in the premixed methane/air flame
were influenced by the pressure difference between the probe and sampling line [55]. In addition
to having a small orifice diameter, the probe tip must be long enough to achieve a large pressure
drop (∆P ≈ 1 atm) and destroy the free active radicals. For each experiment, an approximately
6.4 cm (2.5") long probe was cut from a 10 m long source, using a diamond cutter knife. This
length provides enough pressure drop along the probe. These fused silica microtubes are coated
with a polyimide (graphite-reinforced composite) resin on the outside to provide flexibility and
improve sealing. The coating on the microprobe tip quickly burns off once it is exposed to high
temperatures in a flame. The uncoated probe tip is quite brittle. The most suitable probe size,
43
with the least perturbation of flow fields, was found to be tubes with 200 µm ID and 350 µm
OD. As shown in Figure 3.5, the FS probe tip was connected to a 1/8" stainless steel (SS) tubes
using a 1/8"-to-1/16" SS reducing union20. One-piece polyimide21 (graphite) fused silica 1/16"
adapters22 were used to seal the connection between the FS tube and the SS reducing union.
Figure 3.5: Schematic of microprobe head (1/8"-to-1/16"reducing union)
A custom design stand was manufactured23 to hold the probe firmly on a single-axis translation
stage24. The stage was mounted on another 2-axis stage. This assembly allowed motion in the
XYZ directions. The 1/8" SS tubes were wrapped with Omega heating tapes and insulators.
20 VICI Valco 1/8"-to-1/16" microbore external HPLC column end fitting (Model ECEF211.0F)
21 Polyimide withstand high temperatures up to 350 ºC whereas other available option, PEEK, is for lower
temperature (up to 175 ºC) applications
22 VICI Valco 1/16" one piece FS adapter (Model FS 1.4-5 for tubing with 350 ≤ OD ≤ 400 µm)
23 At the Mechanical and Industrial Engineering machine shop, University of Toronto
24 LT1 Thorlabs 50 mm Travel Translation Stage
1/16”-350µm FS adapter 1/8” SS tubing
SS ferrule 350µm OD FS probe tip
Flow Direction From Flame To Vacuum Pump
44
The tubes were then connected to a 1/8", 8-ft long SS heated transfer line. The temperature of
transfer line was set at 210 ºC. The pressure of the line was monitored by a vacuum gauge placed
before the pump (on the vacuum side). Between the pressure gauge and the pump, a filter25 was
arranged to collect the fine particles (≥15 µm diameter soot particles), which were carried along
with sample from the flame, to prevent any damage to the pump and downstream instrument. A
high-temperature two-way ball valve was used between the filter and the pressure gauge to shut
off the line when needed (e.g. while checking for leakage). All the lines, from the heated transfer
line, to the pump, and from the pump, to the GC-FID, were heated by several heating tapes to
prevent fuel condensation, especially in the filter.
3.5.2 Sampling Procedure
To assure repeatability of the measurements, a precise sampling procedure was established to be
performed step-by-step throughout each experiment. Prior to sampling, the pump should be
warmed up at least 30 minutes.
3.5.2.1 Detecting the Leaks
Detecting and eliminating leaks in the sampling line is the most critical step in preparing for a
successful flame sampling. A leak from ambient air into the lines will dilute the collected sample
25 Model SS-4TF-15; sintered with nominal pore size of 15µm
45
gas and will result in lower species concentrations (particularly for those species identified on the
TCD). To prevent any leakage into the system, the following practice is advised.
Before inserting the FS tube into the front of probe, the front opening of the reducing union
was capped with a SS plug. The pump, which was turned on beforehand, then immediately
creates a vacuum in the line from the tip of probe (plugged) to the pump. At this point, the
pressure gauge should show the vacuum pressure of about 81 kPa (24 in. Hg), which is the
maximum possible vacuum pressure produced by the pump. Since suction side was heated, the
pressure might drop slightly below 81 kPa (~85 kPa). Next, the ball valve was closed and pump
was turned off to check for any major leakage(s). If a rapid change in the pressure was observed,
there must have been a major leakage (more than 10 sccm) in the line; otherwise, the line can be
checked for a minor leak (less than 10 sccm). Major leaks into the sampling line were detected
using a container filled with dry ice (i.e. solidified CO2) and a few drops of water (to expedite
CO2 sublimation). The container was placed near suspected leakage points (e.g. connections) for
several minutes. Unless a spike of CO2 was detected by NDIR analyzer downstream (see Section
3.6.2) at any point, this would indicate that there was not a major leak present in the sampling
line. If no major leak was observed, the flowrate at the end of the line was checked (see Figure
3.1). When the flow meter showed an absolute zero (0.0 sccm), the sampling probe and the
transfer line were considered leak-free and ready for the next step: centring. After an already
prepared FS tube was inserted into the probe, the tip of the tube was plugged and flow was
checked to assure no leak was caused by insertion of the FS tube.
46
3.5.2.2 Centring the Burner
Collecting reproducible data throughout experiments requires exact identification of the
centreline. The consistency in following an identical procedure prior to each experiment is
critical to find the centreline. Centring was accomplished with the aid of a laser beam generator
and a centring piece. The setup is shown in the following picture.
Figure 3.6: The centring process
The burner was fastened to a translation stage26, and the stage was mounted on a jack27. The
horizontal displacement was tuned by a micrometer knob and the changes in vertical motion
were measured by a calliper attached to the jack. The combined stage and jack manoeuvre,
enables measuring the radial and centreline profile species concentrations. As mentioned in
26 LT1 single-axis stage with a micrometer knob
27 Thorlabs Lab Jack (Model M EL-120)
Centring Piece
Sampling
Probe
Laser Beam
47
Section 3.5.1, the probe could move along the XYZ axes. Prior to getting a flame, the centring
piece was inserted into the opening of the fuel nozzle. Upon shining the laser over the burner, a
bright red dot appeared on the screen opposite to the laser. The burner, jointly with the centring
piece, was brought up to the point whereby the tip of the centring piece just covered the laser
point. Every precaution was taken to place the tip of the microprobe exactly on the top of
centring piece tip perpendicularly. Since the centre of the burner was essentially fixed visually,
human eye error was inevitable. To verify that the position of the probe was centred correctly,
the flame was generated while the probe should have already been at or adjacent to the
centreline. A number of CO and CO2 measurements were taken in the neighbourhood of
initially-estimated centre, by moving the burner in horizontal direction in small increments (e.g.
0.05 mm steps). At the same height, hypothetically, the minimum CO and CO2 (or any other
species) concentrations should occur at the centre of the flame sheet. The domain of this
adjustment usually did not go beyond ±0.5 mm of the initial position determined by laser. The
CO and CO2 measurements were done by TCD instead of NDIR, due to low sensitivity of the
NDIR (see Sections 3.6.1.1 and 3.6.2).
3.5.2.3 Sampling the Flame
Majority of the previous two steps in sampling procedure were done before a flame was lit. Once
the flame was generated, the sampling probe was inserted back into the flame. Having centred
the burner, the probe remained stationary during the experiment and instead the burner was
48
moved vertically and/or horizontally. As described in the previous section, preliminary
measurements were critical to verify the centreline location. It is recommended to start sampling
from mid-low section of the flame for two main reasons: (1) the upper region of the flame may
be highly sooting and result in fast clogging of the probe, and (2) too low in the flame contains
excessive amount of unburned fuel which can saturate the FID. Therefore, the starting point was
selected at either 16 mm or 14 mm above the fuel nozzle, depending on the type of the flame
and then throughout the experiment the burner was moved downward or if possible upward (for
z ≤14 mm).
Once a stable flame was obtained and the flame temperature field reached a steady state, the
heated vacuum pump was turned on and gases withdrawn from the flame continuously. The
heated sample line was flushed for at least 40 mins before the first run. The samples traveled
from the flame, passed through the heated vacuum pump and sent to the analyzer section. On
the way out to the ventilation, exhaust flow is measured by a gas flow meter28. The exhaust
flow29 was monitored to capture clogging or otherwise observe the flow trends at each point in
the flame. The lower in the flame, the lower the temperature, and consequently the higher the
gas density is. The flowrate is known to be a function of gas density. As the probe distanced from
28 Humonics Veri-Flow 500 Electronic Flow meter
29 Note that this flow could be lower than actual suction flowrate due to leaks in the line after the pump. However, a
relative flow is of the significance for the purpose of this study.
49
the fuel port (i.e. towards tip of the flame), the flowrate decreased from about 70 sccm in the
lower region, to less than 10 sccm at the maximum point of sampling. Another reason for this
drop in sampling flowrate was the increase in soot concentration and its coagulation at the probe
tip. The latter rationale, however, was dominating closer to the luminous region rather than
lower regions in the flame. As a result, the sampling and purge time varied depending on the
location of the probe in the flame. Lower in the flame, sampling points required short purge
times of about 5 – 10 minutes. In contrast, closer to the tip of the flame at least 40 – 50 minutes
were required to purge the line prior to sampling.
The burner’s position was adjusted with an accuracy of 0.01 mm in both vertical and
horizontal directions. Typically, a 2 mm vertical and 0.5 mm horizontal spacings were used
between each data point. More data points were chosen when further investigation was
necessary. The horizontal spacing was smaller than the vertical one due to sharper radial
concentration changes compared to the centreline profile.
The sampling process for sooting flames (e.g. CTL flame) was more challenging than a less
sooting flame (e.g. GTL flame). The effort to burn the soot mass accumulated on the tip of the
probe using a propane torch was unsuccessful. Larger probe size (320 µm ID) was also tested
with the hope to increase the sample collection time for sooting regions before clogging. Yet, not
only did the probe clog quickly, but it also disturbed the flame structure considerably (shortened
the flame length by extracting large amount of fuel).
50
3.6 Analytical Techniques
To analyze flame samples, a GC-FID was tied in series to a GC-TCD, followed by an NDIR
spectrometer. This set of analytical devices enabled us to measure C1 – C6 hydrocarbons, carbon
dioxide, carbon monoxide, oxygen and some oxygenated compounds.
3.6.1 Principles of Gas Chromatography
Gas chromatography is a technique used to separate compounds based on their differences in the
interactions with a flowing mobile phase (carrier gas) and a stationary phase (separation column). The
mobile phase carries the mixture of interest through a separation column in a controlled manner. Because
of the differences in interaction between the mixture’s components with both phases, the mobile phase
convey components at different rates, so they are retained on column for different times [56]. This
selective separation is known as partitioning. Usually, larger HC molecules arrive later to the end of the
column compared to the lighter ones. The amount of time that a given component spends in the
separation column is called the retention time (RT). To determine the RT for each component, detectors
are used at the end of column. A plot of detector response, which is in form of peaks versus time, is called
a chromatogram. Besides the RT, the size of the response peak can be obtained from a chromatogram.
The area underneath each peak corresponds to the concentration of that specific compound. The sharper
the peak, the better the separation is. Partitioning strongly depends on temperature. Therefore, for a
better separation, carrier gas passes through a separation column placed in a temperature controlled oven.
Separation of a sample with a range of boiling points is achieved by starting at a low temperature and then
increasing the temperature until less volatile compounds are eluted. Calibration gases are used as a
51
reference for the peak size or/and to find the RT. The flow of sample gas and carrier gas into the injector
and then the column is controlled by the rotary gas sampling valve (GSV). Gas chromatographs are
categorized according to their applications and the type of detectors used with them. The thermal
conductivity (TCD) and flame ionization (FID) detectors are the two most common detectors. The
requirement of a GC detector depends on its selectivity and separation application.
3.6.1.1 GC–TCD
The TCD operates on the principle that a hot body (the filament) loses heat at a precise rate
depending on the thermal properties of components that flow through the detector. This heat
loss is used to detect elution of analytes from the column. The main advantage of TCD over
most of other detectors is the ability to detect N2 and O2. Helium (He) is typically used as a
carrier gas because of its distinctive higher thermal conductivity than most organic compounds.
Since thermal conductivity of He and H2 are very close (6=) = 0.168 >?.@, 6= = 0.142 >
?.@),
detection of H2 with He as a carrier gas was not possible. Using other noble gases as carrier, such
as argon (Ar) (with 6A+ = 0.016 >?.@), sacrifices the detection of other important species such as
CO and CO2 with thermal conductivities similar to the argon’s (6BC = 0.023 >?.@ , 6BC) = 0.015
>?.@). For a TCD to be effective, the thermal conductivity of analytes must be significantly
different than that of carrier gas. One way to solve this problem is to use a dual TCD system,
one detector running on He as carrier gas (current experiment) and the other one on Ar to
identify hydrogen (H2) [57]. Another separate set of GSV and columns would be required.
52
Figure 3.7: Schematic of dual column GC-TCD setup
A Varian 450-GC was used in this study. Ultra pure He Grade 5.0 (99.999% purity), with
the minimum inlet pressure of 552 kPa (80 psig), was chosen as the carrier and make-up gas.
Instrument air at 414 kPa (60 psig) was used for the valve operation. The GC is equipped with
Electronic Flow Control (EFC) injector. Half a meter long Hayesep Q and 1.5 m long Molsieve
packed columns30 with 2 mm ID were used in series for separation. The maximum temperatures
that hayesepe and molecular sieve columns withstand are 165 ºC and 400 ºC, respectively. TCD
(filament) temperature limit is 390 ºC. The first GSV has ten ports, while the second one
(GSV2) has six. The GC-TCD was remotely controlled by Galaxie Ver. 1.9 chromatography
software.
30 Mesh size of 80-100 with UltiMetal® column material
53
Method and Oven Temperature Profile
Detailed drawings of gas analyzing steps of the GC-TCD are included in Appendix B. Samples
continuously flowed through a 1 mL sample loop and bypassed the columns to the ventilation.
The filament was fixed at 300 ºC. Once flame sample was injected, the column oven was kept at
an initial temperature of 50 ºC for 10.0 minutes. Then the temperature was increased with the
rate of 8 ºC/min for 5.0 minutes and held for one minute at the final temperature of 90 ºC.
Upon sample injection, analyte was swept with the carrier gas onto the pre-column. Lighter
molecules such as O2, N2, CH4, and CO were trapped on the molecular sieve column while CO2
and C2-isomers were directly sent to the TCD. In the final stage, smaller molecules on molsieve
column (O2, CO, etc.) were eluted. Consequently, CO2, C2H2 and C2H4 peaks showed up first
on chromatogram (see sample chromatogram of GC-TCD in Appendix C). Other peaks (i.e.
O2, N2, CH4 and CO peaks) eluted after 10 minutes when temperature of the oven rose.
3.6.1.2 GC–FID
The FID employs an ionization detection method. In an FID, organic compounds are burned in
a tiny H2/air flame. Ions generated are then attracted to a collector plate, which produces a
current depending on type and quantity of ions. In general, FID uses capillary columns and has a
higher detection limit (more sensitive) than TCD. The FIDs are insensitive to water, CO, CO2,
and NOX.
54
Figure 3.8 illustrates the schematic diagram of the GC-FID setup used in this experiment.
A Varian 3800 GC with electronic flow controllers, an injector, a methanizer, and two FID’s
were used in this study. The methanizer was connected to the rear column for detection of
oxygenated species. The inlet pressure of H2, air and He were 276, 414 and 552 kPa (40, 60 and
80 psig), respectively. The GC-FID’s GSV is a 10 port rotary valve. Samples passed through a
Y-splitter, where they were split into two 50 m-long Plot and Poraplot U columns with 530 µm
ID. Similar to GC-TCD, the device was controlled and acquired data by Galaxie software.
Figure 3.8: Schematic of dual column GC-FID setup
55
Method and Oven Temperature Profile
The carrier gas, helium, flowed at the rate of 2.0 mL/min in the columns. The oven temperature
was initially set at 50 ºC. The column oven temperature profile is shown in Figure 3.9
Figure 3.9: GC-FID column oven temperature program
Most of low molecular weight species (e.g. methane, ethane, ethylene, propylene, etc.) elute
during the first temperature ramp from the third to the eighth minutes. Less volatile species elute
during the five-minute constant temperature at 150 ºC. Finally, the temperature was held at
180 ºC for 20 minutes for the remaining high boiling point components to release and also bake
the column by forcing the least volatile compounds out of column. The GC-FID method is
more than twice as long as the GC-TCD method (34.5 mins vs. 16 mins). The rear column on
GC-FID (connected to a methanizer) was primary used for the detection of oxygenated
compounds for alcohol fuel blends.
0
50
100
150
200
0 5 10 15 20 25 30
Temperature (ºC)
Time (min)
High Boiling Point Components
Elution + Baking the Column
34.5 mins
180°C
56
3.6.1.3 Calibration of Gas Chromatography
Most of GC measurements were calibrated using calibration gases from Scotty® Specialty
Gases31. Calibrations were performed by flowing calibration gases at the average flowrate of the
flame sampling (approximately 50 sccm) directly into the GC sample loop. The GCs’ operating
conditions during calibration were the same as the conditions during sampling species from the
flame. A full set of calibration for all gases was performed each time prior to new fuel being
tested.
CO, CO2 and O2
A mixture of 0.5% CO, CO2, O2 and H2 was used for calibration of the lower concentrations of
CO, CO2 and O2 on the GC-TCD. Linde calibration gas containing a 10% CO and CO2
mixture was used for higher range of CO and CO2 levels. Note that the FID-methanizer can be
used for detecting low concentrations (ppm level) of CO and CO2 where TCD is not applicable.
Non-Oxygenated Hydrocarbons
A mixture of 1000 ppm C1 – C6 alkanes (methane, ethane, propane, n-butane, n-pentane, n-
hexane), C1 – C6 alkenes (ethylene, propylene, 1-butene, 1-pentene and 1-hexene) and acetylene
were used to calibrate these species on GC-FID. Some other alkynes, i.e. methylacetylene
31 48 Liters @ 300 psig, 21 ºC in balance of nitrogen
57
(propyne), 2-butyne and 1-butyne (also acetylene) were calibrated at the lower concentration of
15 ppm. Benzene was calibrated using a calibration tank containing 100 ppm of benzene in
balance of air.
Oxygenated Hydrocarbons
In addition to the above molecules, the GC-FID was calibrated for two important oxygenated
hydrocarbons in combustion: formaldehyde (CH2O) and acetaldehyde (C2H4O). These two
compounds should theoretically be present in Hex20-GTL flame in larger concentrations than
any other flame. Since these compounds are highly reactive and susceptible to rapid degradation,
using calibration gas cylinders is not a reliable method. In the current study, permeation tube
devices were used for calibration. The schematic diagram of a permeation tube device is displayed
below.
Figure 3.10: Permeation tube setup
58
The permeation device consists of a permeable tube filled with the chemical of interest, an
oven32, and a carrier gas. When the tube is placed in an oven and heated to a specific
temperature, the chemical compound permeates from the tube walls at a particular mass flowrate.
The temperature setting and corresponding permeation rate are provided by the supplier. An
inert carrier gas sweeps over the permeation tube and carries away a uniform concentration of the
chemical from the oven chamber towards the analyzer (GC-FID in this study). In this
experiment, nitrogen (carrier gas) was purified prior to entering the oven chamber. The
concentration of gas mixture can be determined by Equation (3.3).
D =< × F24.46
3I� JK�
�3.3�
where C is the concentration in ppm, MWi is the molecular weight of the species of interest in
g/mole, P is the permeation rate in ng/min provided by the manufacturer of tubes, Fc is the total
flow of the carrier gas in mL/min and 24.46 is the molar volume of nitrogen at STP.
Response Factors
Schofield has suggested that organic molecules have relative responses on FID according to their
effective FID carbon number (or also known as FID molar response factor) [58]. That is, the
32 VICI Dynacalibrator Model 150
59
chromatographic response signal for equivalent concentrations of many hydrocarbons can be
calculated based on the response signal of others. For example, if the FID response for X ppm
methane, with molar response factor of 1, is Y units, then the response for X ppm (same amount)
of ethylene with response factor of ~2, is ~2Y units. The FID relative molar response factors for
some of the applicable compounds for this study are listed in the following table. This method
was used to verify the calibration gases method quantitatively.
Table 3-4: A sample of comparison between measured and literature FID relative molar response
factors for a range of organic molecules [58]
Molecule Effective FID
Carbon Number
Measured
Response (µV.min)
Literature
Response (µV.min)
Methane 1.00 5256 5256
Ethylene 1.99 11428 10512
Acetylene 2.20 10842 11563
Benzene a 6.00 3748 3154
a Note that except benzene, which was calibrated at 100 ppm, other compounds calibrated at 1000 ppm
3.6.2 Non-Dispersive Infrared Analysis
The non-dispersive infrared (NDIR) sensor is a simple spectroscopic device used to measure gas
concentration based on infrared energy absorption characteristics of the gas [50]. In the current
60
study, the NDIR33 instrument was primarily exercised for the diagnosis of the steady state, based
on CO and CO2 concentration changes. It was zeroed each time prior to the experiment and
calibrated using a Linde 10% CO and CO2 mixture for the high range and a 0.5% Scotty gas for
the low range. The readouts for both high and low levels of CO and CO2 percentages are located
on the front panel of the device. NDIR was connected downstream from the GC-TCD and
before the sample exited to the ventilation. A water-bath cooling system and a filter were
implemented midway between GC-TCD and NDIR to remove condensed fuel from the gases.
The NDIR measurements are helpful for real-time analyses, yet, very crude assessment. For
instance, for centring the burner, which data points are only 0.1 mm apart from each other, GC-
TCD had to be used for sensitive comparisons between measurements, even though it took
much longer time to accomplish the centring task. The NDIR diagnosis, on the other hand,
provided sufficiently accurate information on whether steady state was reached. Upon changing
the sampling location (by moving the burner), it took between 5 to 45 minutes for the NDIR to
stabilize, depending on the probe location. Based on the previous discussion in Section 3.5.2.3,
as suction flowrates decreases for sampling points higher up in the flame, longer transition times
were perceived. A minimum time of 40 – 50 minutes was required to achieve steady state in
many cases where the flames were highly sooting (e.g. CTL and Jet A-1 flames).
33 NOVA NDIR Analyzer Model 7800P2A
61
Chapter 4
4. Results & Discussions
The primary goal of this study is to measure the gaseous species in coflow diffusion flames for
conventional and alternative jet fuels. The species profiles of these fuels are compared in this
chapter. The sampling analyses were carried out by gas chromatography and major species that
were identified included but not limited to carbon monoxide, carbon dioxide, oxygen, methane,
ethane (C2H6), ethylene (C2H4), propylene (C3H6), and acetylene (C2H2). For a number of fuels,
the concentration of other species, such as benzene (C6H6), propyne (C3H4), and 1-butene
(C4H8) were also reported. The GTL-hexanol blend flame was investigated for the presence of
acetaldehyde and formaldehyde. A few other species (e.g. propane, n-hexane or 2-butyne) were
identified but not reported because either they were below the limit of detection (LOD) or limit
of quantification (LOQ). Some of the lighter HC’s such as, CH4 and C2-isomers, can be
identified on both FID and TCD. Since the FID is more sensitive and accurate, measurements
determined by GC-FID were reported in this study. Both response factors and calibration gas
methods produced close results (within ±10%). The calibration gas method, however, was
preferred as the standard method of calibration for this study. Each experiment was repeated for
a minimum of three times. Since the results were reproducible within ±15%, the measured values
for each data point were averaged over the trials. The outliners are also reported separately.
62
4.1 Jet A-1 Flame
Jet A-1 was the first fuel to be tested and was used as the base fuel for the alternative jet fuels.
Preliminary studies were done on the first batch of fuel during early stages of developing the
present experimental setup. The second set of measurements was executed on a fresh batch of
fuel and the results were compared. Both results were identical. A numerical study of this
experiment was also performed and its results were published in a work by Saffaripour and
colleagues [11]. Later in this section, the experimental and numerical results are compared.
a) Flame Characteristics
Figure 4.1 shows a photograph of the bottom portion of Jet A-1 flame during sampling. A liftoff
of about 1.7 mm ± 0.2 mm was measured using digital processing of the picture. The flame was
moderately sooting and was composed of approximately 11 mm of blue flame front at the lower
region. The visible flame height was about 55 mm.
Figure 4.1: Bottom portion of a typical Jet A-1 flame (sampling in progress)
63
b) CO & CO2 Concentration Profiles
The centreline concentration profiles of CO and CO2 are shown in terms of mole fraction in
Figure 4.2. Soot accumulation on the probe tip limited sampling to the lower half (up to z = 28
mm) of the total centreline. Maximum concentrations of 2.4% and 4.9% were measured for
[CO]34 and [CO2].
Figure 4.2: Jet A-1 CO and CO2 centreline concentration profiles
Figure 4.3 on the next page, presents these two species concentration variations along the
flame radius at the heights (z) of 12 mm and 14 mm, respectively. The probe clogged as it
approached the flame wings at just after 3 mm and 2.5 mm away from the centre of the flame for
heights of 12 mm and 14 mm, correspondingly. The flame radius is larger at lower regions.
34 The symbol [X] is used interchangeably with “X concentration” to avoid the overuse of word “concentration”.
0
2
4
6
0 10 20 30
Mole Fraction
z (mm)
CO2
CO
×10-2
64
Figure 4.3: Jet A-1 CO and CO2 radial concentration profiles (a) z = 12 mm (b) z = 14 mm
c) Species Concentration Profiles
Figures 4.4 and 4.5 show the major species concentrations along the centreline and radial
profiles, respectively. Similar to CO and CO2 measurements, soot blockage of the probe tip
prevented further sampling. The measurements follow a smooth increasing trend, as expected.
Figure 4.4: Jet A-1 centreline concentration profiles (a) CH4 & C2H6 (b) C2H4, C2H2 & C3H6
0
1
2
3
4
5
0 0.5 1 1.5 2 2.5 3 3.5
Mole Fraction
r (mm)
(a)
CO2
CO
×10-2
0
1
2
3
4
5
0 0.5 1 1.5 2 2.5 3
Mole Fraction
r (mm)
(b)
CO2
CO
×10-2
0
2
4
6
8
10
0 10 20 30
Mole Fraction (ppm)
z (mm)
(a)
CH4
C2H6
×103
0
4
8
12
16
20
0 10 20 30
Mole Fraction (ppm)
z (mm)
(b)
C2H4
C2H2
C3H6
×103
65
Figure 4.5: Jet A-1 species radial concentration profiles (a) z =12 mm, (b) z = 14 mm
The benzene, 1-butene and propyne peaks co-eluted with other peaks, hence they could not be
quantified (lower than LOQ).
d) Modeling
The surrogate mixture mentioned in Section 2.1.3, and a detailed chemical kinetic mechanism
used by Dagaut et al. [27] combined with the mechanism developed by Appel et al. [59], which
contains the reactions describing the PAHs growth to pyrene, were used to model Jet A-1 in the
present study. The model consisted of 2265 reactions involving 304 species. The computational
domain extended 12.29 cm in the axial direction and 4.57 cm in the radial direction, and was
divided into 192 (z) × 88 (r) control volumes. The grid was finest in the flame region with the
maximum resolution of 0.2 mm between r = 0 and r = 8 mm in radial direction, and 0.25 mm
between z = 0 and z = 8 cm in the axial direction. The computational domain was solved using
192 × 4.7 GHz CPUs. Figures 4.6 and 4.7 compare measurements with the numerical model by
Saffaripour et al. [11].
0
2
4
6
8
0 0.5 1 1.5 2 2.5
Mole Fraction(ppm)
r (mm)
(a)
C2H4
C2H2
CH4
C3H6
C2H6
×103
0
2
4
6
8
10
0 0.5 1 1.5 2 2.5
Mole Fraction (ppm)
r (mm)
(b)
C2H4
C2H2
CH4
C3H6
C2H6
×103
66
Figure 4.6: Computational (model) and experimental (exp) comparisons of CO & CO2 mole
fractions for Jet A-1 flame along (a) centreline [11] and (b) radial (z = 12 mm) profiles
Figure 4.7: Computational (model) and experimental (exp) comparison of species centreline
mole fractions for Jet A-1 flame along (a) CH4 & C2H6 (b) C2H4 & C2H2 (c) & C3H6 [11]
0
2
4
6
0 10 20 30
Mole Fraction
z (mm)
(a)
CO2 (exp)
CO2 (model)
CO (exp)
CO (model)
×10-2
0
1
2
3
4
5
0 1 2 3
Mole Fraction
r (mm)
(b)
CO2 (exp)
CO2 (model)
CO (exp)
CO (model)
×10-2
0
2
4
6
8
10
12
0 10 20 30
Mole Fraction (ppm)
z (mm)
(a)CH4 (exp)
CH4 (model)
C2H6 (exp)
C2H6 (model)
× 103
0
10
20
30
40
0 10 20 30
Mole Fraction (ppm)
z (mm)
(b)C2H4 (exp)
C2H4 (model)
C2H2 (exp)
C2H2 (model)
×103
0
2
4
6
8
10
12
0 10 20 30
Mole Fraction (ppm)
z (mm)
(c)
C3H6 (exp)
C3H6 (model)
×103
67
The model predictions agree well with measured CO, CO2 (both radial and centreline),
C2H6 and C2H2 concentrations. The model moderately overpredicts CH4, C3H6 and C2H4
concentrations, in particular at higher sampling points. This overprediction of species can be
attributed to variety of reasons, one of which is the underestimation of liftoff by the model. The
computed temperature profile by Saffaripour et al. shows a smaller flame liftoff than observed
experimental liftoff. Figure 4.8 demonstrates the computed Jet A-1 temperature profile where
the flame sheet temperature rises to above 1,650 K at the height of 1.75 mm, a few millimetres
below visually observed liftoff.
Figure 4.8: Computed temperature isotherm for Jet A-1 laminar coflow diffusion flame by
Saffaripour et al. [11]
68
In addition to experimental (systematic and human) errors, three possible sources of errors in
the model may be present: (1) combined Appel and Dagaut jet fuel chemical kinetic
mechanisms, (2) input fuel and oxidizer exit temperature from nozzle, and (3) the fuel surrogate.
Dr. Dworkin, one of the coauthors on the modeling study by Saffaripour et al., suggests that the
error in the predicted liftoff may originate from elimination of a few essential ignition reactions
in mechanism [60]. The largest difference between model and experiments was observed in the
case of ethylene concentration. Ethylene, as one of the most important species in soot formation
(see Section 2.4), could have been miscalculated by the model. It should be noted that soot
concentration computation is one of the weaknesses of the model at the current stage. The liftoff
is also very sensitive to the temperature boundary conditions at the fuel and oxidizer exit [60].
Besides, surrogate fuel used in this model consists of normal paraffinic (69% n-decane) and no
branched paraffinic, while the analysis by ARC (Table 3-1) showed more than 13% of iso-
paraffinics in Jet A-1. The numerical and experimental works done by Sarathy et al. [61]
compared gaseous species from n-octane and 2-methylheptane (branched octane isomer) in
opposed-flow diffusion flames. This study showed that n-octane flame produces approximately
50% more ethylene than 2-methylheptane flame. Hence, it is expected that substituting a few
percentages of n-decane in the surrogate fuel with branched isomers of decane, for instance 2-
methylnonane, may noticeably reduce the predicted ethylene concentrations by the model. Note
that iso-decane was the largest iso-paraffinic compound in Jet A-1 analysis (refer to Table 3-1).
69
Error bars are shown in Figure 4.6 and 4.7. Based on a number of trials and sensitivity
analyses, different errors have been suggested for the comparisons between measured and
computed data. The +1 mm right-sided horizontal error bars show inaccuracy in centring the
probe (location in the z direction). The left-sided horizontal error bars, not only consider the
imprecision of centring the probe, but also includes ~ 2 mm liftoff which is not well represented
in the model predictions. Thus, the left-sided horizontal error bars are -3 mm. Another way to
represent the liftoff is to shift the model 2 mm to the right (positive direction of z axis). In
general, the ±1 mm error bars for each data point are below 15% of total covered sampling
height. For instance at the height of 10 mm, the horizontal error bar is 10% (1 mm/10 mm), and
at the height of 25 mm it is 4% (1 mm/25 mm). The vertical error bars of ±15%, on the other
hand, correspond to the errors involved with calibration, GC analyses and/or any possible leak.
The vertical error bars are determined based on relative standard deviation (RSD) of all four
trials. All things considered, the agreement is excellent between numerical and experimental
results.
In general, for all other fuels a conservative value of ±15% uncertainties were considered in
concentration calculation (vertical bars) and ±1 mm for errors associated with centring the probe
(horizontal bars). To avoid redundancy, the error bars are not shown on the graphs for other
fuels.
70
4.2 Gas-to-Liquid Flame
a) Flame Characteristics
Figure 4.9 shows sampling from a GTL flame at the height of 30 mm where soot starts to build
up on the probe tip. The blue flame region was noticeably longer than that of Jet A-1. As a result
of zero aromatics concentration in GTL fuel, the luminous sooting region of flame was brighter
yellow and in general the flame was visibly less sooting. Therefore, the available sampling
domain for the GTL flame was wider than that of Jet A-1 in the both horizontal and vertical
directions. The flame length was similar to the Jet A-1 visible flame height. The flame height
and liftoff were about 56 mm and 2 mm, respectively. The GTL flame was slightly less stable
than Jet A-1’s flame.
Figure 4.9: GTL flame during sampling at the height of z = 30 mm in the flame
71
b) CO & CO2 Concentration Profiles
Samples were collected in the locations as high as 36 mm in the flame, which was about 2/3 of
the total visible flame height. Figure 4.10 demonstrates [COX] changes along the centreline. The
radial concentration profiles in Figure 4.11 show a sudden drop in [CO], as CO converts to
CO2, while passing through the oxidation zone. The [CO2] decreased as the probe tip was
moved away from the flame wing in the radial direction.
Figure 4.10: GTL jet fuel CO and CO2 centreline concentration profiles
Figure 4.11: GTL jet fuel species radial concentration profiles (a) z =14 mm, (b) z = 18 mm
0
2
4
6
8
0 10 20 30 40
Mole Fraction
z (mm)
CO2
CO
×10-2
0
2
4
6
8
10
0 2 4 6
Mole Fraction
r (mm)
(a)
CO2
CO
×10-2
0
2
4
6
8
10
0 2 4 6
Mole Fraction
r (mm)
(b)
CO2
CO
×10-2
72
c) Species Concentration Profiles
Due to the larger available sampling domain, the species concentration profiles, shown in Figure
4.12, provide a good indication of the formation and destruction steps of different species (stable
or unstable) in the coflow diffusion flame. While most of major species peak around 30 mm
above the fuel nozzle, the acetylene, the most stable HC in the flame, concentration continues to
grow. In fact, [C2H2] should start to decrease higher up the flame based on HACA growth,
discussed in Section 2.4. The ethylene concentration was found to be the largest among other
measured species with the maximum of 40,400 ppm at the height of z = 30 mm.
Figure 4.12: GTL centreline concentration profiles (a) CH4 & C2H6 (b) C2H4, C2H2 & C3H6
It is noteworthy that GTL chromatogram on GC-FID had a much clearer spectrum with
less number of peaks (meaning fewer compounds) and a better separation compared to Jet A-1
flame. The benzene and 1-butene and propyne concentrations were lower than LOD of 100
ppm. At higher heights in the flame, 1-butene peak co-eluted with another peak.
0
5
10
15
0 10 20 30 40
Mole Fraction (ppm)
z (mm)
(a)
CH4
C2H6
×103
0
10
20
30
40
50
0 10 20 30 40
Mole Fraction (ppm)
z (mm)
(b)
C2H4
C2H2
C3H6
×103
4.3 Coal-to-Liquid
a) Flame Characteristics
The CTL flame was highly sooting
naphthenics (see Section 2.1.2.1
listed in Table 2-4. As shown in
a CTL flame, which distinguished
flame length was comparable to the ones of previous fuels.
about 55 mm and 2 mm, respectively.
Due to large soot concentration
at low heights. Note that at low heights
sampling from these regions
Flame
was highly sooting as the fuel contains large amount
2.1.2.1). This is also consistence with the low smoke point
As shown in Figure 4.13 below, high soot luminosity wa
which distinguished it from other flames. The blue flame front was
flame length was comparable to the ones of previous fuels. The flame height and lift
, respectively.
Figure 4.13: CTL highly sooting flame
Due to large soot concentrations in the flame sheet, radial measurements were unattainable, even
at low heights, there is an excessive amount of unburned fuel and
would not provide a useful insight towards the flame
73
large amounts of aromatics and
low smoke point of CTL,
below, high soot luminosity was the main feature of
. The blue flame front was minimal. The
The flame height and liftoff were
in the flame sheet, radial measurements were unattainable, even
excessive amount of unburned fuel and
flame structure.
74
b) CO & CO2 Concentration Profiles
According to Figure 4.14, the maximum concentrations of 2.5% and 4.6% were recorded for CO
and CO2, respectively, at the height of z = 26 mm. This height was the lowest maximum
sampling height among all the experimental fuels.
Figure 4.14: CTL jet fuel CO and CO2 centreline concentration profiles
c) Species Concentration Profiles
Figure 4.15 not only exhibits the trend among major species concentrations as in the previous
fuels, but also includes the propyne and benzene concentration profiles (Figure 4.15-c). The
benzene concentration could partly be from the benzene content of the fuel, especially in the
lower region of the flame. A benzene outliner in one of the trials, C6H6 (2), is shown separately
with a diamond sign. A sample chromatogram is attached in Appendix C.
0
1
2
3
4
5
0 10 20 30
Mole Fraction
z (mm)
CO2
CO
×10-2
75
Figure 4.15: CTL jet fuel centreline concentration profiles (a) CH4 & C2H6 (b) C2H4, C2H2 &
C3H6 (c) C3H4 & C6H6
The concentration data for the maximum sampling height, z = 28 mm (circled), are unusually
low. Soot partially clogging the probe can justify these low concentrations. When the probe is
partially clogged, the sampling suction flow drops from about 70 sccm to less than 10 sccm.
Hence, either the sampling line may have not been fully flushed at that point even after 50
minutes, or the fine leaks in the line had a noticeable effect on diluting the sampling. It should
also be noted that the calibration of species was done at higher flowrates (~ 50 sccm).
0
2
4
6
8
10
0 10 20 30
Mole Fraction (ppm)
z (mm)
(a)
CH4
C2H6
×103
0
2
4
6
8
10
12
14
0 10 20 30
Mole Fraction (ppm)
z (mm)
(b)
C2H4
C2H2
C3H6
×103
0
2
4
6
8
10
12
0 10 20 30
Mole Fraction (ppm)
z (mm)
(c)
C3H4
C6H6
C6H6 (2)
×102
76
4.4 Gas-to-Liquid Blend with Hexanol Flame
Similar to the GTL fuel, this blend has no aromatics and therefore, a low sooting flame was
expected. The Hex20-GTL fuel has a strong fruity (apple) odour, which is attributed to the
presence of hexanol. The 20 vol.% of hexanol in the fuel is large enough to potentially increase
the concentration of some important oxygenated compounds, such as acetaldehyde and/or
formaldehyde, in its flame. Therefore, the GC-FID was also calibrated for these two species
using the permeation tubes as discussed in Section 3.6.1.3. These compounds were expected to
appear on the rear column of GC-FID, after mixing with hydrogen, passing through the
methanizer and converting to ethane and methane, respectively. In the current study, CH2O and
C2H4O concentrations, however, were below LOQ and their peaks did not secure a certain RT.
Hence, no results are reported on these compounds in this study.
a) Flame Characteristics
The Hex20-GTL flame physical descriptions (e.g. flame height of about 55 mm ± 5 mm,
stability, soot luminosity, etc.) were identical to those of GTL flame. The flame liftoff was 1.8
mm ± 0.2 mm, similar to previous flames.
b) CO & CO2 Concentration Profiles
Figure 4.16 shows [CO] and [CO2] increasing along the centreline. The [CO] and [CO2] peak
at 3.8% and 6.2%, respectively, at the height of 36 mm.
77
Figure 4.16: Hex20-GTL jet fuel CO and CO2 centreline concentration profiles
c) Species Concentration Profiles
Major species concentration profiles for the Hex20-GTL flame are plotted against the location
of the probe in Figure 4.17. Similar to the GTL flame, a much wider domain was available for
sampling. Within the sampling range, all the major species’ peaks, including acetylene, were
captured. The [C4H8] was first among other measured species to climax at about 3,000 ppm,
between 28 – 30 mm above the fuel nozzle. Acetylene was the last species to reach a high plateau
of about 13,000 ppm at the height of approximately 32 mm. Besides CO and CO2, ethylene was
found to be the most abundant measured species with a peak concentration of 43,500 ppm at
about two-thirds of the flame length, z = 30 mm. Below the height of 14 mm, unburned fuel
saturated the GC-FID columns. Therefore, those data points were removed from analyses.
0
2
4
6
8
0 10 20 30 40
Mole Fraction
z (mm)
CO2
CO
×10-2
78
Figure 4.17: Hex20-GTL jet fuel centreline concentration profile (a) CH4 & C2H6 (b) C2H4,
C2H2 & C3H6 (c) C4H8
4.5 Species Comparison
Figure 4.18 compares the CO and CO2 concentration profiles for all the fuels along the
centreline. For all the cases, [CO2] is constantly higher than [CO] and higher up in the flame it
deviates even more. A linear increase for both [CO] and [CO2] was observed within the
sampling frame of z = [8 36] mm. The [CO2] increases, however, with about twice the rate of
0
5
10
15
20
0 10 20 30 40
Mole Fraction (ppm)
z (mm)
(a)
CH4
C2H6
×103
0
10
20
30
40
50
0 10 20 30 40
Mole Fraction (ppm)
z (mm)
(b)
C2H4
C2H2
C3H6
×103
0
10
20
30
40
0 10 20 30 40
Mole Fraction (ppm)
z (mm)
(c)
C4H8
×102
79
[CO]. The CO2 concentration is highest for CTL and Jet A-1 flames while it is lowest for the
Hex20-GTL flame.
Figure 4.18: CO and CO2 centreline concentration profiles comparison of experimental fuels
Figure 4.19 compares the major measured species concetrations for the CTL flame with
those of Jet A-1. The next three figures (Figures 4.20 – 4.22) compare the species in GTL
flames with those of CTL, Jet A-1 and Hex20-GTL flames, respectively.
Hex20-GTL CO2
(m = 0.2284)
R² = 0.9966
General CO
(m ≈ 0.1367)
R² ≈ 0.9950
CTL CO2
(m = 0.2645)
R² = 0.9827
0
1
2
3
4
5
6
7
8
0 5 10 15 20 25 30 35 40
Mole Fraction
z (mm)
CO2 (H20-GTL) CO (H20-GTL)
CO2 (Jet A-1) CO (Jet A-1)
CO2 (GTL) CO (GTL)
CO2 (CTL) CO (CTL)
×10-2
80
Figure 4.19: Species centreline concentration comparison between CTL jet fuel and Jet A-1
A closer look at Figure 4.19 reveals that CTL has slightly higher concentrations of CH4,
C2H6 and C3H6. Note that in the CTL and Jet A-1 flames, which have similar soot luminosity,
the C2H2 and C2H4 concentrations are very similar.
Figure 4.20 compares the GTL and CTL flame species. A group of data points on the GTL
are shown in Figure 4.20 graphs that are within the common sampling domain between both the
GTL and the CTL flames (i.e. 8 ≤ z ≤ 28).
0
2
4
6
8
10
0 10 20 30
Mole Fraction (ppm)
z(mm)
CH4
CTL
Jet A-1
×103
0
0.5
1
1.5
2
0 10 20 30z (mm)
C2H6
CTL
Jet A-1
×103
0
4
8
12
16
20
24
0 10 20 30z(mm)
C2H4
CTL
Jet A-1
×103
0
4
8
12
0 10 20 30
Mole Fraction (ppm)
z (mm)
C2H2
CTL
Jet A-1
×103
0
2
4
6
8
0 10 20 30z (mm)
C3H6
CTL
Jet A-1
×103
81
Figure 4.20: Species centreline concentrations comparison between CTL and GTL jet fuels
The comparison between species concentration of these two fuels did not exhibit a major
difference except in the cases of acetylene and in particular ethylene. Since GTL fuel has
considerably higher concentrations of n-paraffinics than CTL fuel (see Figure 3.2), the higher
concentrations of both ethylene and acetylene in the GTL flame compared to the CTL flame
agree with findings by Sarathy et al. [61].
The reasoning behind the unusually low concentrations for the last two CTL flame data
points (circled on the graphs) was previously discussed at the end of Section 4.3.
0
2
4
6
8
10
12
0 10 20 30
Mole Fraction (ppm)
z(mm)
CH4
CTL
GTL
×103
0
1
2
3
0 10 20 30z (mm)
C2H6
CTL
GTL
×103
0
10
20
30
40
0 10 20 30z(mm)
C2H4
CTL
GTL
×103
0
4
8
12
0 10 20 30
Mole Fraction (ppm)
z (mm)
C2H2
CTL
GTL
×103
0
2
4
6
8
10
12
0 10 20 30z (mm)
C3H6
CTL
GTL
×103
82
Figure 4.21: Species centreline concentrations comparison between Jet A-1 and GTL jet fuels
Figure 4.21 compares the major species concentration for Jet A-1 and GTL jet fuels. The
trends are similar to the ones from Figure 4.20 for the comparison of the GTL and the CTL
flames. Also, similar to the GTL and Jet A-1 species concentration comparison, the graphs only
show the limited common portion of data for both flames (i.e. 8≤ z ≤ 28). In general, the GTL
flame has larger concentrations of measured hydrocarbon species.
0
2
4
6
8
10
12
0 10 20 30
Mole Fraction (ppm)
z(mm)
CH4
Jet A-1
GTL
×103
0
1
2
3
0 10 20 30z (mm)
C2H6
Jet A-1
GTL
×103
0
10
20
30
40
0 10 20 30z(mm)
C2H4
Jet A-1
GTL
×103
0
4
8
12
0 10 20 30
Mole Fraction (ppm)
z (mm)
C2H2
Jet A-1
GTL
×103
0
2
4
6
8
10
12
0 10 20 30z (mm)
C3H6
Jet A-1
GTL
×103
83
Figure 4.22: Species centreline concentrations comparison between GTL and Hex20-GTL fuels
Figure 4.22 demonstrates the similarities among the measured species concentrations for the
GTL and Hex20-GTL fuels. As mentioned in Section 4.4, these two flames share a similar
physical appearance too. Except acetylene, all other species follow identical trend in both flames.
Acetylene concentration appears to peak at the height of z = 32 mm in the Hex20-GTL flame,
while its concentration still rises up to the highest sampling point, z = 36 mm in the GTL flame.
0
2
4
6
8
10
12
14
16
0 10 20 30 40
Mole Fraction (ppm)
z(mm)
CH4
Hex20-GTL
GTL
×103
0
1
2
3
4
0 10 20 30 40z (mm)
C2H6
Hex20-GTL
GTL
×103
0
10
20
30
40
50
0 10 20 30 40z(mm)
C2H4
Hex20-GTL
GTL
×103
0
4
8
12
16
20
24
0 10 20 30 40
Mole Fraction (ppm)
z (mm)
C2H2
Hex20-GTL
GTL
×103
0
2
4
6
8
10
12
0 10 20 30 40z (mm)
C3H6
Hex20-GTL
GTL
×103
84
4.6 Comparison with Coflow Ethylene Diffusion Flame
The coflow ethylene diffusion flame has been investigated extensively by many researchers due to
its importance in understanding of soot formation [34,36,45] . Most studies do not include
species measurements, however, Smooke et al. [62], measured centreline acetylene
concentrations, and thus was chosen for acetylene comparison between ethylene and these flames
of complex fuel mixtures.
Table 4-1: Acetylene level comparison in ethylene and Hex20-GTL coflow diffusion flames
Fuel Ethylene Ethylene Hex20-GTL
Chemical formula C2H4 C2H4 C8.76H19.53O0.27
Dilution ratio (mol %) 60 80 4.6
Hydrogen-to-Carbon (H/C) ratio 2.0 2.0 2.2
Carbon atom balance (atom mole /
100 moles of fuel mixture)
120 160 40.5
Flame height (Lf, mm) 50 71 55
Normalized peak acetylene (ppm) 14,500 12,700 12,800
Peak location (z, mm) 21 26 32
85
The Hex20-GTL flame data set was chosen because it includes the acetylene peak. Hence,
the maximum concentration of the C2H2 in Hex20-GTL flame was compared with the
normalized peak concentration of C2H2 in ethylene coflow flames. The normalized acetylene
peak was calculated based on maximum acetylene concentration in the mentioned study by
Smooke et al. multiplied by the ratio of dilution. The sample calculations is shown in Appendix
E. In the study by Smooke et al., ethylene was diluted with nitrogen at different dilution ratios.
As it can be seen from Table 4-1, the normalized peak for acetylene is relatively in a same range
as of acetylene concentration in Hex20-GTL flame. Note that the flames for this experiment are
lifted while the flames in mentioned study by Smooke et al. are not.
86
Chapter 5
5. Conclusions & Recommendations
This study investigated gaseous species concentration profiles in sooting laminar jet fuel coflow
diffusion flames. The developed method for vaporizing the jet fuel was proven to be robust, and
the flames produced were stable. Extra precaution was taken into consideration for centring the
burner and taking measurements in order to produce repeatable measurements. The results were
reproducible with a relative standard deviation (RSD) of 10%. The conservative ±15%
uncertainty was considered for the concentration measurements in this study. This value was
obtained based on rigorous sensitivity analyses and multiple trials.
5.1 Conclusions
The performance of the Controlled Evaporative Mixer unit in vapourizing jet fuels was
extremely satisfactory. The residence time for the vapourizer, the lag time between commending
a change on the control box and observing the result in the flame, was less than 10 seconds.
The new sampling setup has two main advantages. On one hand, the sampling flowrate was
large enough that steady state was often reached within 5 – 10 minutes, depending on the
location of the probe. The suction flowrate, on the other hand, was low enough to leave the
flame intact.
87
The visible flame heights for all the flames were observed about 55 mm. The liftoff was kept
below 2 mm at the maximum value of 1.8 mm ± 0.2 mm.
This study provides valuable set of experimental data on coflow flame characterization of Jet
A-1 and other alternative synthetic jet fuels used in this study. These data can be used to validate
the model similar to the ones shown for Jet A-1.
While CO2 centreline concentration varied from one fuel to another, CO concentrations
were almost identical for all the fuels. The Jet A-1 and CTL flames had the highest CO2
concentrations, while the lowest concentrations of CO2 were observed in the Hex20-GTL flame.
Concentration profiles of species, except ethylene, were relatively similar among all the fuels.
The concentrations of the most abundant species in the flame from the highest to the lowest
were; CO2, CO, C2H4, CH4, C2H2, C3H6 and C2H6. Results from both GTL and Hex20-GTL
flames indicate that the concentrations of measured species reached their maximums at the
heights between 28 mm to 32 mm. These two flames produced very close concentrations of
major species. C6H6 and C3H4 were measured in CTL flames, whereas 1-butene was quantified
only in Hex20-GTL flame. The higher concentration of C2H4 and C2H2 in GTL flames
compared to CTL flames can be attributed to the higher i-paraffinic content of GTL fuel.
The model by Saffaripour et al. [11] well reproduced the experimentally measured CO, CO2,
C2H6 and C2H2 concentrations in the Jet A-1 flame. Although the CH4 and C3H6 measured
concentrations were slightly overpredicted, they were within experimental uncertainties. The
88
model, however, moderately overpredicted C2H4 concentrations, in particular around the mid
height of the flame. It is concluded that this overprediction was partly due to underestimation of
liftoff by the model and/or lack of i-paraffinic compounds in the surrogate fuel. The comparison
between ethylene and experimental fuels in this study (1) shows that the measurements were
reasonable, (2) the original motivation behind studying the ethylene flames is confirmed.
5.2 In-Progress Work
Temperature measurement by rapid insertion method is under development. This method
employs a 75 µm diameter R-type thermocouple (Pt-Pt/13%Rh). The raw measurements must
be then corrected for radiation heat losses from the thermocouple wires and soot. The soot
volume fraction is also being measured and studied for all the fuels.
A thermal desorption method to measure heavy PAH (e.g. naphthalene, phenanthrene,
pyrene, etc.) concentrations is under investigation. The result of this work will be a valuable
complementary study to the current research. Also, our Combustion Research Group is currently
working on the modeling of GTL, CTL and Hex20-GTL flames.
5.3 Future Works
The study of GTL and naphthenics blend, the fourth alternative jet fuel provided by ALFA-
BIRD, would be very beneficial. This blend is a promising fuel for substituting conventional jet
89
fuel, as both GTL and naphthenic compounds are currently produced in large commercial scale.
Naphthenic HCs provide the missing saturated cyclic structure in SPK fuel.
The Hex20-GTL fuel requires further investigation, in particular, in case of oxygenated
species studies. The GC-FID should be recalibrated for acetaldehyde, formaldehyde and
additionally calibrated for butaldehyde (or any higher aldehydes) and esters.
5.3.1 Recommendations
• Since a more detailed composition of Jet A-1 is in hand for this experiment, a surrogate
fuel can be modified accordingly. For instance, iso-paraffinic group, which composed
more than 13% of Jet A-1, is suggested to be represented by branched alkanes in the new
surrogate fuel. It is also suggested to run experiments on the current surrogate fuel and
compare the results with both experimental and numerical study of Jet A-1.
• The jet fuel model well predicts most of the measurements. However, the model slightly
overpredicts some species concentrations, in particular, for ethylene. It is recommended
that the soot and chemical kinetics model be further refined for a better agreement
between model and experiment for poorly predicted species. Combustion Research
Group is actively working on improving the soot model.
• The temperature and the velocity of the fuel exit should be checked more precisely. This
would possibly improve liftoff prediction by model.
90
• Another GC-FID can be dedicated for detecting larger HC’s than C4-isomers and
expand the temperature ramp on the current GC-FID for better separation of lower
molecular weight species. Use of micro-GC for detection of single species, such as
acetaldehyde, is advised. Hydrogen can be identified by using another TCD running on
argon carrier gas.
• It is strongly recommended to reinvestigate the presence of CH2O and C2H4O in
Hex20-GTL flame. The oven temperature profile on GC-FID needs to be modified for
better separation method. The retention times for CH2O and C2H4O on rear column are
10 and 11.3 min, respectively, using the current method which coincides with many other
C4 and larger isomers’ peaks. By changing the method, achieving a better separation for
these two species and other oxygenated species on the rear column is foreseeable.
• As far as modeling, use GTL for comparison: (1) easier to model the soot because of its
lower concentrations, and (2) more data points in hand to validate model.
• The laser beam used for centring the burner can be more focused, thus, providing a
higher precision in centring.
91
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100
Appendices
Appendix A: Jet A-1 composition & thermophysical properties of all jet fuels ...................101
Appendix B: Step-by-Step sample analysis on GC-TCD .................................................... 129
Appendix C: Sample gas chromatograms ............................................................................ 133
Appendix D: Governing equations ...................................................................................... 137
Appendix E: Sample calculations ........................................................................................ 141
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Summary by Group
Recovery = 100.00
Group %Wgt %Vol %Mol
Aromatics 27.658 25.407 29.618
I-Paraffins 13.774 15.067 13.690
Naphthenes 6.553 6.667 7.295
Olefins 2.173 2.420 2.450
Paraffin 21.974 24.237 20.299
Oxygenates 0.000 0.000 0.000
Unidentified 27.868 26.202 26.646
Plus 0.000 0.000 0.000
102
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Summary by Carbon
Recovery = 100.00
C# %Wgt %Vol %MolC7 0.270 0.282 0.405C8 3.304 3.409 4.346C9 14.464 14.879 16.830C10 22.148 22.773 23.076C11 18.159 18.084 17.350C12 8.478 8.666 7.339C13 3.061 3.306 2.400C14 1.722 1.842 1.254C15 0.424 0.448 0.288C16 0.103 0.109 0.066
103
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Composite by Carbon
Recovery = 100.00
Group C# %Wgt %Vol %MolAromatics C7 0.088 0.083 0.138
C8 1.465 1.376 1.994C9 6.064 5.640 7.301
C10 7.656 7.003 8.297C11 8.873 8.038 8.764C12 3.512 3.267 3.125
I-Paraffins C8 0.238 0.275 0.301C9 2.262 2.549 2.549
C10 5.540 6.146 5.628C11 4.566 4.838 4.222C12 1.167 1.259 0.991
Naphthenes C7 0.139 0.148 0.205C8 0.872 0.916 1.124C9 2.239 2.287 2.563
C10 3.303 3.316 3.404
Olefins C8 0.224 0.256 0.289C9 1.341 1.495 1.536
C10 0.607 0.670 0.626
Paraffin C7 0.043 0.051 0.062C8 0.504 0.586 0.638C9 2.558 2.908 2.882
C10 5.041 5.639 5.121C11 4.720 5.208 4.365C12 3.798 4.140 3.223C13 3.061 3.306 2.400C14 1.722 1.842 1.254C15 0.424 0.448 0.288C16 0.103 0.109 0.066
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Component List
Recovery = 100.00
Pk# Time Group Component %Wgt %Vol %Mol1 14.671 ? Unidentified 0.002 0.003 0.0042 56.971 P7 200 n-Heptane 0.043 0.051 0.0623 60.378 N7 222 Methylcyclohexane 0.139 0.148 0.2054 67.957 A7 300 Toluene 0.088 0.083 0.1385 71.122 I8 326 2-Methylheptane 0.108 0.126 0.1366 71.375 I8 328 4-Methylheptane 0.034 0.039 0.0437 72.264 N8 335 t-1,4-DiMcycloC6 0.163 0.170 0.2118 72.457 I8 338 3-Ethylhexane 0.096 0.110 0.1229 72.620 O8 340 C8-Diolefin 0.089 0.102 0.115
10 73.525 N8 346 1,1-Dimethylcyclohexane 0.028 0.032 0.037
11 74.350 I9 354 2,2,5-Trimethylhexane 0.029 0.033 0.03312 74.702 N8 360 t-1-E-2-McyC5 0.031 0.033 0.04013 74.922 ? Unidentified 0.048 0.051 0.06214 75.620 O8 370 C8-Olefins 0.135 0.154 0.17415 76.888 N8 390 c-1,4-DiMcycloC6 0.081 0.084 0.10416 77.045 P8 400 n-Octane 0.504 0.586 0.63817 80.123 ? Unidentified 0.015 0.016 0.01618 80.524 N8 432 c-1,2-DiMcycloC6 0.044 0.045 0.05719 80.741 I9 434 2,4-Dimethylheptane 0.075 0.086 0.08520 81.342 N8 442 Propylcyclopentane 0.525 0.552 0.676
21 81.712 N9 450 1,1,3-TriMcycloC6 0.159 0.167 0.18222 82.155 O9 452 C9-Olefins 0.285 0.320 0.32623 82.510 ? Unidentified 0.036 0.041 0.04124 82.643 I9 458 2,5 & 3,5-DMheptane 0.126 0.142 0.14225 82.823 ? Unidentified 0.028 0.032 0.03226 82.947 O9 460 C9-Olefins 0.028 0.031 0.03227 83.128 I9 462 3,3-Dimethylheptane 0.050 0.057 0.05628 83.353 I9 466 C9-Isoparaffin 0.027 0.031 0.03129 83.947 A8 475 Ethylbenzene 0.240 0.226 0.32630 84.133 O9 482 C9-Olefins 0.099 0.111 0.113
31 84.350 I9 485 2,3,4-Trimethylhexane 0.179 0.197 0.20132 84.618 O9 490 C9-Olefins 0.021 0.023 0.02433 85.166 A8 500 m-Xylene 0.598 0.565 0.81534 85.323 A8 502 p-Xylene 0.186 0.176 0.25335 85.495 I9 503 2,3-Dimethylheptane 0.228 0.255 0.25736 85.750 ? Unidentified 0.021 0.023 0.02437 85.941 O9 508 C9-Olefin 0.099 0.111 0.11438 86.148 I9 510 3-Methyl-3-ethylhexane 0.060 0.066 0.06839 86.313 ? Unidentified 0.015 0.017 0.01740 86.555 I9 518 4-MC8+C9-Olefin 0.265 0.301 0.299
41 86.693 I9 520 2-Methyloctane 0.339 0.389 0.38242 87.089 O9 522 C9-Olefin 0.041 0.046 0.04743 87.560 I9 530 3-Methyloctane 0.590 0.664 0.66444 88.173 A8 550 o-Xylene 0.441 0.409 0.60045 88.315 ? Unidentified 0.051 0.057 0.058
105
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Component List
Recovery = 100.00
Pk# Time Group Component %Wgt %Vol %Mol46 88.428 O9 560 C9-Olefin 0.024 0.026 0.02747 89.018 N9 568 t-1-E-4-M-cyC6? 0.226 0.232 0.25948 89.164 N9 570 c-1-E-4-McyC6? 0.442 0.452 0.50649 89.466 I9 572 C9-Isoparaffin 0.294 0.328 0.33150 89.801 ? Unidentified 0.041 0.045 0.04751 89.984 O9 575 1-Nonene 0.073 0.082 0.08452 90.763 O9 590 cis-3-Nonene 0.048 0.053 0.05553 91.079 P9 600 n-Nonane 2.558 2.908 2.88254 91.551 N9 608 1 -M-2-PcycloC5 0.384 0.396 0.43955 91.898 O10 610 C10-Olefin 0.122 0.136 0.126
56 92.122 ? Unidentified 0.013 0.014 0.01357 92.392 I10 614 C10-Isoparaffin 0.166 0.183 0.16958 92.726 A9 616 Isopropylbenzene 0.078 0.074 0.09459 92.872 O9 618 cis-2-Nonene 0.328 0.362 0.37560 93.103 O9 624 C9-Olefin 0.296 0.327 0.33861 93.391 I10 628 3,3,5-Trimethylheptane 0.216 0.237 0.21962 93.649 ? Unidentified 0.104 0.107 0.10763 94.203 I10 638 2,6-Dimethyloctane 0.287 0.322 0.29264 94.356 I10 640 2,5-Dimethyloctane? 0.843 0.935 0.85665 94.541 ? Unidentified 0.076 0.079 0.087
66 94.685 ? Unidentified 0.077 0.080 0.08867 94.800 N9 644 Propylcylohexane 0.271 0.278 0.31068 94.983 ? Unidentified 0.068 0.076 0.06969 95.236 N9 648 1-M-2-EcycloC6 0.757 0.763 0.86770 95.388 ? Unidentified 0.184 0.185 0.21071 95.546 ? Unidentified 0.083 0.092 0.08672 95.665 O10 650 C10-Olefin 0.119 0.131 0.12273 95.867 A9 651 Propylbenzene 0.561 0.532 0.67574 96.082 I10 652 3,3-Dimethyloctane 0.572 0.634 0.58175 96.326 I10 653 3-Methyl-5-ethylheptane 0.061 0.067 0.062
76 96.463 O10 654 C10-Olefin 0.103 0.114 0.10677 96.589 ? Unidentified 0.044 0.041 0.05378 96.714 A9 655 1-Ethyl-3-methylbenzene 0.719 0.679 0.86579 96.954 A9 656 1-Ethyl-4-methylbenzene 0.450 0.427 0.54180 97.565 A9 658 1,3,5-Trimethylbenzene 1.174 1.108 1.41281 97.842 I10 659 2,3-Dimethyloctane 0.077 0.085 0.07882 97.966 ? Unidentified 0.122 0.135 0.12483 98.085 I10 660 5-Methylnonane 0.315 0.351 0.32084 98.271 I10 661 4-Methylnonane 0.786 0.871 0.79885 98.548 I10 662 2-Methylnonane 0.726 0.814 0.737
86 98.661 A9 663 1-Ethyl-2-methylbenzene 0.486 0.448 0.58587 98.923 I10 664 3-Ethyloctane 0.181 0.200 0.18488 99.045 ? Unidentified 0.071 0.078 0.07289 99.254 N10 666 C10-Naphthene 0.756 0.764 0.77990 99.361 ? Unidentified 0.123 0.124 0.127
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Component List
Recovery = 100.00
Pk# Time Group Component %Wgt %Vol %Mol91 99.439 ? Unidentified 0.175 0.195 0.17892 99.588 I10 668 3-Methylnonane 0.042 0.046 0.04293 99.733 O10 670 C10-Olefin 0.263 0.289 0.27194 100.058 I10 671 C10-Isoparaffin 0.092 0.102 0.09395 100.290 A9 673 1,2,4-Trimethylbenzene 1.362 1.269 1.63896 100.470 ? Unidentified 0.444 0.414 0.53497 100.641 I10 674 C10-Isoparaffin 0.415 0.461 0.42198 100.793 I10 675 C10-Isoparaffin 0.515 0.573 0.52399 100.948 I10 676 Isobutylcyclohexane 0.123 0.126 0.125
100 101.138 ? Unidentified 0.067 0.069 0.068
101 101.241 I10 677 C10-Isoparaffin 0.124 0.138 0.126102 101.386 ? Unidentified 0.058 0.064 0.059103 101.518 ? Unidentified 0.019 0.020 0.019104 101.717 N10 692 t-1-M-2-propylcyC6? 0.166 0.167 0.171105 101.922 I11 702 C11-Isoparaffin 0.344 0.381 0.318106 102.207 P10 700 n-Decane 5.041 5.639 5.121107 102.508 ? Unidentified 0.040 0.045 0.037108 102.591 I11 704 C11-Isoparaffin 0.063 0.070 0.058109 102.721 ? Unidentified 0.108 0.120 0.100110 102.968 ? Unidentified 0.091 0.083 0.109
111 103.066 ? Unidentified 0.067 0.061 0.080112 103.176 A9 705 1,2,3-Trimethylbenzene 0.870 0.795 1.047113 103.452 ? Unidentified 0.161 0.178 0.149114 103.605 A10 708 1-M-4-isopropylbenzene 0.209 0.200 0.225115 103.796 I11 709 C11-Isoparaffin 0.327 0.361 0.302116 104.013 ? Unidentified 0.075 0.083 0.070117 104.203 ? Unidentified 0.086 0.073 0.105118 104.354 A9 712 2,3-Dihydroindene 0.363 0.308 0.444119 104.477 ? Unidentified 0.100 0.085 0.122120 104.654 N10 714 sec-Butylcyclohexane 1.502 1.501 1.548
121 104.928 ? Unidentified 0.044 0.048 0.040122 105.019 I11 716 C11-isoParrafin 0.061 0.068 0.057123 105.154 A10 718 1-M-2-isopropylbenzene 0.228 0.213 0.246124 105.263 ? Unidentified 0.165 0.182 0.152125 105.420 N10 722 C10-Naphthene 0.880 0.883 0.906126 105.743 I11 723 C11-Isoparaffin 0.673 0.731 0.622127 105.930 A10 724 1,3-Diethylbenzene 0.220 0.208 0.237128 106.190 A10 725 1-M-3-propylbenzene 1.027 0.974 1.106129 106.380 ? Unidentified 0.163 0.154 0.175130 106.554 A10 727 1-M-4-propylbenzene 0.315 0.300 0.340
131 106.661 A10 728 Butylbenzene 0.291 0.276 0.313132 106.793 A10 729 3,5-DM-1-Ebenzene 0.320 0.303 0.345133 106.961 ? Unidentified 0.228 0.212 0.246134 107.071 A10 730 1,2-Diethylbenzene? 0.178 0.165 0.192135 107.331 A10 736 C10-Aromatic 0.246 0.231 0.265
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File: C:\Star\data\2010\cgsbgo-10-665.cdf FEB 12, 2010 - 08:17:36Sample: GO-10-665 Operator: CHERYL GOULETParameter: C:\SeparationSystems\HCE4\GO-09-5882JETA
Component List
Recovery = 100.00
Pk# Time Group Component %Wgt %Vol %Mol136 107.528 ? Unidentified 0.195 0.183 0.210137 107.632 A10 740 1-M-2-propyl benzene 0.835 0.780 0.900138 107.789 I11 746 5-Methyldecane 0.525 0.537 0.485139 107.945 ? Unidentified 0.062 0.063 0.057140 108.061 I11 750 2-Methyldecane 0.549 0.562 0.508141 108.367 I11 754 C11-Isoparaffin 0.680 0.698 0.628142 108.507 A10 756 1,4-DM-2-Ebenzene 0.342 0.319 0.368143 108.671 A10 758 1,3-DM-4-Ebenzene 0.498 0.464 0.536144 108.798 ? Unidentified 0.098 0.100 0.090145 108.918 I11 762 3-Methyldecane 0.614 0.674 0.567
146 109.062 ? Unidentified 0.030 0.028 0.033147 109.183 A10 764 1,2-DM-4-Ebenz+C1indan 0.518 0.483 0.558148 109.377 ? Unidentified 0.158 0.163 0.146149 109.554 A10 768 1,3-DM-2-Ebenzene 0.125 0.115 0.135150 109.648 ? Unidentified 0.136 0.125 0.147151 109.738 I11 770 C11-Isoparaffin 0.222 0.230 0.206152 109.876 ? Unidentified 0.117 0.121 0.108153 109.988 ? Unidentified 0.142 0.147 0.131154 110.163 I11 775 C11-Isoparaffin 0.509 0.526 0.470155 110.327 ? Unidentified 0.062 0.059 0.060
156 110.506 ? Unidentified 0.310 0.284 0.334157 110.660 A10 785 1,2-DM-3-ethylbenzene 0.242 0.221 0.260158 110.726 ? Unidentified 0.244 0.224 0.263159 110.849 A11 790 1-E-2-isopropylbenzene 0.395 0.364 0.385160 110.987 ? Unidentified 0.119 0.110 0.116161 111.208 P11 800 n-Undecane 4.720 5.208 4.365162 111.384 ? Unidentified 0.391 0.372 0.381163 111.588 ? Unidentified 0.211 0.221 0.179164 111.815 A10 806 1,2,4,5-TetraMbenzene 0.263 0.241 0.284165 111.927 ? Unidentified 0.131 0.120 0.141
166 112.079 A10 810 1,2,3,5-TetraMbenzene 0.520 0.477 0.560167 112.303 ? Unidentified 0.122 0.132 0.103168 112.425 ? Unidentified 0.521 0.482 0.508169 112.665 A11 822 1-tert-B-2-methylbenzen 0.617 0.566 0.602170 112.995 ? Unidentified 0.216 0.201 0.211171 113.079 ? Unidentified 0.117 0.108 0.114172 113.254 ? Unidentified 0.153 0.143 0.149173 113.382 A11 826 1-Ethyl-2-propylbenzene 0.581 0.543 0.567174 113.674 A11 828 C11-Aromatic 0.698 0.655 0.681175 113.817 A11 830 C11-Aromatic 0.330 0.306 0.322
176 113.960 A11 832 C11-Aromatic 0.774 0.732 0.754177 114.162 A11 834 1-Methyl-3-butylbenzene 0.446 0.424 0.435178 114.365 ? Unidentified 0.242 0.218 0.260179 114.430 A11 836 1,2,3,4-TetraMbz+C11aro 0.395 0.357 0.425180 114.525 ? Unidentified 0.111 0.105 0.108
108
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File: C:\Star\data\2010\cgsbgo-10-665.cdf FEB 12, 2010 - 08:17:36Sample: GO-10-665 Operator: CHERYL GOULETParameter: C:\SeparationSystems\HCE4\GO-09-5882JETA
Component List
Recovery = 100.00
Pk# Time Group Component %Wgt %Vol %Mol181 114.740 A11 842 C11-Aromatic 0.332 0.308 0.324182 114.946 A11 844 C11-Aromatic 0.703 0.653 0.686183 115.173 A11 846 C11-Aromatic 0.384 0.356 0.375184 115.253 ? Unidentified 0.443 0.411 0.432185 115.435 I12 848 C12-Isoparaffin 0.308 0.329 0.262186 115.512 ? Unidentified 0.462 0.492 0.392187 115.790 ? Unidentified 0.711 0.598 0.777188 115.910 A10 850 1,2,3,4-Tetrahydronapht 0.362 0.305 0.396189 116.246 A10 858 Naphthalene 0.915 0.729 1.032190 116.451 A11 865 C11-Aromatic 0.106 0.098 0.103
191 116.533 ? Unidentified 0.203 0.188 0.197192 116.701 ? Unidentified 0.161 0.149 0.157193 116.794 I12 875 C12-Isoparaffin 0.210 0.227 0.178194 116.932 I12 880 C12-Isoparaffin 0.249 0.269 0.211195 117.130 A11 884 C11-Aromatic 0.475 0.437 0.463196 117.253 I12 888 C12-Isoparaffin 0.130 0.141 0.110197 117.435 A12 890 1,3-Dipropylbenzene 1.093 0.976 0.972198 117.642 ? Unidentified 0.127 0.113 0.113199 117.754 ? Unidentified 0.257 0.281 0.218200 117.871 ? Unidentified 0.201 0.219 0.170
201 118.012 P12 895 n-Dodecane 3.798 4.140 3.223202 118.182 I12 898 C12-Isoparaffin 0.270 0.294 0.229203 118.275 ? Unidentified 0.121 0.131 0.102204 118.468 ? Unidentified 0.285 0.264 0.277205 118.618 A11 905 C11-Aromatic 0.313 0.291 0.305206 118.741 ? Unidentified 0.283 0.263 0.276207 118.855 ? Unidentified 0.059 0.056 0.053208 118.959 A12 910 1,3,5-Triethylbenzene 1.001 0.947 0.891209 119.101 ? Unidentified 0.512 0.484 0.456210 119.322 ? Unidentified 0.129 0.120 0.126
211 119.426 A11 915 C11-Aromatic? 0.270 0.250 0.263212 119.557 ? Unidentified 0.055 0.051 0.054213 119.712 A11 920 C11-Aromatic 0.302 0.280 0.294214 119.818 ? Unidentified 0.157 0.146 0.153215 119.937 ? Unidentified 0.089 0.082 0.087216 120.068 ? Unidentified 0.364 0.344 0.324217 120.179 ? Unidentified 0.262 0.248 0.233218 120.302 A12 925 1-t-B-4-ethylbenzene 0.223 0.210 0.198219 120.553 ? Unidentified 0.671 0.621 0.597220 120.615 A12 930 1,2,4-Triethylbenzene 0.216 0.200 0.192
221 120.715 ? Unidentified 0.176 0.163 0.157222 120.838 ? Unidentified 0.214 0.198 0.190223 121.057 ? Unidentified 0.431 0.410 0.383224 121.162 ? Unidentified 0.471 0.449 0.419225 121.426 A12 935 1-M-4-pentylbenzene 0.880 0.838 0.783
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File: C:\Star\data\2010\cgsbgo-10-665.cdf FEB 12, 2010 - 08:17:36Sample: GO-10-665 Operator: CHERYL GOULETParameter: C:\SeparationSystems\HCE4\GO-09-5882JETA
Component List
Recovery = 100.00
Pk# Time Group Component %Wgt %Vol %Mol226 121.662 ? Unidentified 0.586 0.558 0.521227 121.790 ? Unidentified 0.213 0.202 0.189228 121.947 ? Unidentified 0.169 0.161 0.150229 122.036 ? Unidentified 0.504 0.480 0.449230 122.262 ? Unidentified 1.099 1.046 0.978231 122.406 ? Unidentified 0.173 0.164 0.154232 122.547 A12 940 Hexylbenzene 0.100 0.095 0.089233 122.620 ? Unidentified 0.169 0.160 0.150234 122.835 ? Unidentified 0.158 0.129 0.160235 122.992 A11 942 2-Methylnaphthalene 1.060 0.866 1.078
236 123.206 ? Unidentified 0.570 0.466 0.580237 123.481 P13 945 n-Tridecane 3.061 3.306 2.400238 123.609 ? Unidentified 0.211 0.228 0.166239 123.711 ? Unidentified 0.094 0.101 0.074240 123.859 A11 947 1-Methylnaphthalene 0.689 0.552 0.701241 124.011 ? Unidentified 0.124 0.099 0.126242 124.142 ? Unidentified 0.300 0.240 0.305243 124.382 ? Unidentified 0.430 0.344 0.437244 124.484 ? Unidentified 0.574 0.459 0.583245 124.721 ? Unidentified 0.164 0.131 0.167
246 124.792 ? Unidentified 0.087 0.070 0.088247 124.890 ? Unidentified 0.109 0.115 0.113248 124.970 ? Unidentified 0.073 0.077 0.075249 125.078 ? Unidentified 0.151 0.159 0.156250 125.233 ? Unidentified 0.395 0.418 0.407251 125.505 ? Unidentified 0.180 0.190 0.185252 125.633 ? Unidentified 0.206 0.217 0.212253 125.756 ? Unidentified 0.118 0.125 0.122254 125.904 ? Unidentified 0.668 0.705 0.688255 126.082 ? Unidentified 0.209 0.221 0.215
256 126.198 ? Unidentified 0.104 0.110 0.107257 126.316 ? Unidentified 0.387 0.409 0.399258 126.535 ? Unidentified 0.537 0.437 0.496259 126.874 ? Unidentified 0.406 0.330 0.375260 127.059 ? Unidentified 0.159 0.129 0.147261 127.248 ? Unidentified 0.599 0.488 0.554262 127.403 ? Unidentified 0.083 0.068 0.077263 127.476 ? Unidentified 0.048 0.039 0.045264 127.565 ? Unidentified 0.068 0.056 0.063265 127.844 ? Unidentified 0.347 0.282 0.321
266 128.092 P14 965 n-Tetradecane 1.722 1.842 1.254267 128.246 ? Unidentified 0.108 0.115 0.078268 128.383 ? Unidentified 0.288 0.308 0.209269 128.475 ? Unidentified 0.161 0.172 0.117270 128.608 ? Unidentified 0.137 0.146 0.099
110
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File: C:\Star\data\2010\cgsbgo-10-665.cdf FEB 12, 2010 - 08:17:36Sample: GO-10-665 Operator: CHERYL GOULETParameter: C:\SeparationSystems\HCE4\GO-09-5882JETA
Component List
Recovery = 100.00
Pk# Time Group Component %Wgt %Vol %Mol271 128.706 ? Unidentified 0.060 0.049 0.056272 128.821 ? Unidentified 0.065 0.053 0.060273 128.873 ? Unidentified 0.086 0.070 0.079274 129.061 ? Unidentified 0.329 0.268 0.304275 129.236 ? Unidentified 0.237 0.193 0.219276 129.436 ? Unidentified 0.066 0.054 0.061277 129.545 ? Unidentified 0.039 0.032 0.036278 129.651 ? Unidentified 0.051 0.041 0.047279 129.743 ? Unidentified 0.040 0.032 0.037280 129.845 ? Unidentified 0.029 0.023 0.026
281 129.960 ? Unidentified 0.114 0.093 0.105282 130.114 ? Unidentified 0.132 0.108 0.122283 130.210 ? Unidentified 0.079 0.064 0.073284 130.334 ? Unidentified 0.092 0.074 0.085285 130.386 ? Unidentified 0.058 0.047 0.054286 130.470 ? Unidentified 0.118 0.095 0.109287 130.565 ? Unidentified 0.127 0.103 0.118288 130.812 ? Unidentified 0.362 0.292 0.334289 131.066 ? Unidentified 0.097 0.078 0.090290 131.218 ? Unidentified 0.014 0.011 0.012
291 131.307 ? Unidentified 0.012 0.013 0.008292 131.455 ? Unidentified 0.045 0.048 0.031293 131.586 ? Unidentified 0.019 0.021 0.013294 131.768 ? Unidentified 0.007 0.008 0.005295 131.981 ? Unidentified 0.034 0.036 0.023296 132.141 P15 980 n-Pentadecane 0.424 0.448 0.288297 132.398 ? Unidentified 0.009 0.010 0.006298 132.605 ? Unidentified 0.023 0.025 0.016299 132.789 ? Unidentified 0.009 0.009 0.006300 132.915 ? Unidentified 0.019 0.020 0.013
301 133.311 ? Unidentified 0.018 0.019 0.012302 133.472 ? Unidentified 0.034 0.036 0.023303 133.713 ? Unidentified 0.025 0.026 0.017304 133.934 ? Unidentified 0.021 0.023 0.015305 134.014 ? Unidentified 0.012 0.013 0.008306 134.149 ? Unidentified 0.010 0.011 0.007307 134.344 ? Unidentified 0.055 0.058 0.035308 134.530 ? Unidentified 0.040 0.042 0.025309 134.843 ? Unidentified 0.017 0.018 0.011310 135.818 P16 985 n-Hexadecane 0.103 0.109 0.066
311 136.238 ? Unidentified 0.008 0.009 0.005312 137.658 ? Unidentified 0.014 0.014 0.008313 138.057 ? Unidentified 0.004 0.004 0.002314 139.235 ? Unidentified 0.023 0.024 0.013315 139.625 ? Unidentified 0.011 0.011 0.006
111
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File: C:\Star\data\2010\cgsbgo-10-665.cdf FEB 12, 2010 - 08:17:36Sample: GO-10-665 Operator: CHERYL GOULETParameter: C:\SeparationSystems\HCE4\GO-09-5882JETA
Component List
Recovery = 100.00
Pk# Time Group Component %Wgt %Vol %Mol
112
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Components by Group
Recovery = 100.00
Group Time Component %Wgt %Vol %MolAromatics 67.957 300 Toluene 0.088 0.083 0.138
83.947 475 Ethylbenzene 0.240 0.226 0.32685.166 500 m-Xylene 0.598 0.565 0.81585.323 502 p-Xylene 0.186 0.176 0.25388.173 550 o-Xylene 0.441 0.409 0.60092.726 616 Isopropylbenzene 0.078 0.074 0.09495.867 651 Propylbenzene 0.561 0.532 0.67596.714 655 1-Ethyl-3-methylbenzene 0.719 0.679 0.86596.954 656 1-Ethyl-4-methylbenzene 0.450 0.427 0.54197.565 658 1,3,5-Trimethylbenzene 1.174 1.108 1.41298.661 663 1-Ethyl-2-methylbenzene 0.486 0.448 0.585
100.290 673 1,2,4-Trimethylbenzene 1.362 1.269 1.638103.176 705 1,2,3-Trimethylbenzene 0.870 0.795 1.047103.605 708 1-M-4-isopropylbenzene 0.209 0.200 0.225104.354 712 2,3-Dihydroindene 0.363 0.308 0.444105.154 718 1-M-2-isopropylbenzene 0.228 0.213 0.246105.930 724 1,3-Diethylbenzene 0.220 0.208 0.237106.190 725 1-M-3-propylbenzene 1.027 0.974 1.106106.554 727 1-M-4-propylbenzene 0.315 0.300 0.340106.661 728 Butylbenzene 0.291 0.276 0.313106.793 729 3,5-DM-1-Ebenzene 0.320 0.303 0.345107.071 730 1,2-Diethylbenzene? 0.178 0.165 0.192107.331 736 C10-Aromatic 0.246 0.231 0.265107.632 740 1-M-2-propyl benzene 0.835 0.780 0.900108.507 756 1,4-DM-2-Ebenzene 0.342 0.319 0.368108.671 758 1,3-DM-4-Ebenzene 0.498 0.464 0.536109.183 764 1,2-DM-4-Ebenz+C1indan 0.518 0.483 0.558109.554 768 1,3-DM-2-Ebenzene 0.125 0.115 0.135110.660 785 1,2-DM-3-ethylbenzene 0.242 0.221 0.260110.849 790 1-E-2-isopropylbenzene 0.395 0.364 0.385111.815 806 1,2,4,5-TetraMbenzene 0.263 0.241 0.284112.079 810 1,2,3,5-TetraMbenzene 0.520 0.477 0.560112.665 822 1-tert-B-2-methylbenzen 0.617 0.566 0.602113.382 826 1-Ethyl-2-propylbenzene 0.581 0.543 0.567113.674 828 C11-Aromatic 0.698 0.655 0.681113.817 830 C11-Aromatic 0.330 0.306 0.322113.960 832 C11-Aromatic 0.774 0.732 0.754114.162 834 1-Methyl-3-butylbenzene 0.446 0.424 0.435114.430 836 1,2,3,4-TetraMbz+C11aro 0.395 0.357 0.425114.740 842 C11-Aromatic 0.332 0.308 0.324114.946 844 C11-Aromatic 0.703 0.653 0.686115.173 846 C11-Aromatic 0.384 0.356 0.375115.910 850 1,2,3,4-Tetrahydronapht 0.362 0.305 0.396116.246 858 Naphthalene 0.915 0.729 1.032116.451 865 C11-Aromatic 0.106 0.098 0.103117.130 884 C11-Aromatic 0.475 0.437 0.463117.435 890 1,3-Dipropylbenzene 1.093 0.976 0.972118.618 905 C11-Aromatic 0.313 0.291 0.305118.959 910 1,3,5-Triethylbenzene 1.001 0.947 0.891
113
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File: C:\Star\data\2010\cgsbgo-10-665.cdf FEB 12, 2010 - 08:17:36Sample: GO-10-665 Operator: CHERYL GOULETParameter: C:\SeparationSystems\HCE4\GO-09-5882JETA
Components by Group
Recovery = 100.00
Group Time Component %Wgt %Vol %MolAromatics 119.426 915 C11-Aromatic? 0.270 0.250 0.263
119.712 920 C11-Aromatic 0.302 0.280 0.294120.302 925 1-t-B-4-ethylbenzene 0.223 0.210 0.198120.615 930 1,2,4-Triethylbenzene 0.216 0.200 0.192121.426 935 1-M-4-pentylbenzene 0.880 0.838 0.783122.547 940 Hexylbenzene 0.100 0.095 0.089122.992 942 2-Methylnaphthalene 1.060 0.866 1.078123.859 947 1-Methylnaphthalene 0.689 0.552 0.701
I-Paraffins 71.122 326 2-Methylheptane 0.108 0.126 0.13671.375 328 4-Methylheptane 0.034 0.039 0.04372.457 338 3-Ethylhexane 0.096 0.110 0.12274.350 354 2,2,5-Trimethylhexane 0.029 0.033 0.03380.741 434 2,4-Dimethylheptane 0.075 0.086 0.08582.643 458 2,5 & 3,5-DMheptane 0.126 0.142 0.14283.128 462 3,3-Dimethylheptane 0.050 0.057 0.05683.353 466 C9-Isoparaffin 0.027 0.031 0.03184.350 485 2,3,4-Trimethylhexane 0.179 0.197 0.20185.495 503 2,3-Dimethylheptane 0.228 0.255 0.25786.148 510 3-Methyl-3-ethylhexane 0.060 0.066 0.06886.555 518 4-MC8+C9-Olefin 0.265 0.301 0.29986.693 520 2-Methyloctane 0.339 0.389 0.38287.560 530 3-Methyloctane 0.590 0.664 0.66489.466 572 C9-Isoparaffin 0.294 0.328 0.33192.392 614 C10-Isoparaffin 0.166 0.183 0.16993.391 628 3,3,5-Trimethylheptane 0.216 0.237 0.21994.203 638 2,6-Dimethyloctane 0.287 0.322 0.29294.356 640 2,5-Dimethyloctane? 0.843 0.935 0.85696.082 652 3,3-Dimethyloctane 0.572 0.634 0.58196.326 653 3-Methyl-5-ethylheptane 0.061 0.067 0.06297.842 659 2,3-Dimethyloctane 0.077 0.085 0.07898.085 660 5-Methylnonane 0.315 0.351 0.32098.271 661 4-Methylnonane 0.786 0.871 0.79898.548 662 2-Methylnonane 0.726 0.814 0.73798.923 664 3-Ethyloctane 0.181 0.200 0.18499.588 668 3-Methylnonane 0.042 0.046 0.042
100.058 671 C10-Isoparaffin 0.092 0.102 0.093100.641 674 C10-Isoparaffin 0.415 0.461 0.421100.793 675 C10-Isoparaffin 0.515 0.573 0.523100.948 676 Isobutylcyclohexane 0.123 0.126 0.125101.241 677 C10-Isoparaffin 0.124 0.138 0.126101.922 702 C11-Isoparaffin 0.344 0.381 0.318102.591 704 C11-Isoparaffin 0.063 0.070 0.058103.796 709 C11-Isoparaffin 0.327 0.361 0.302105.019 716 C11-isoParrafin 0.061 0.068 0.057105.743 723 C11-Isoparaffin 0.673 0.731 0.622107.789 746 5-Methyldecane 0.525 0.537 0.485108.061 750 2-Methyldecane 0.549 0.562 0.508108.367 754 C11-Isoparaffin 0.680 0.698 0.628
114
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Components by Group
Recovery = 100.00
Group Time Component %Wgt %Vol %MolI-Paraffins 108.918 762 3-Methyldecane 0.614 0.674 0.567
109.738 770 C11-Isoparaffin 0.222 0.230 0.206110.163 775 C11-Isoparaffin 0.509 0.526 0.470115.435 848 C12-Isoparaffin 0.308 0.329 0.262116.794 875 C12-Isoparaffin 0.210 0.227 0.178116.932 880 C12-Isoparaffin 0.249 0.269 0.211117.253 888 C12-Isoparaffin 0.130 0.141 0.110118.182 898 C12-Isoparaffin 0.270 0.294 0.229
Naphthenes 60.378 222 Methylcyclohexane 0.139 0.148 0.20572.264 335 t-1,4-DiMcycloC6 0.163 0.170 0.21173.525 346 1,1-Dimethylcyclohexane 0.028 0.032 0.03774.702 360 t-1-E-2-McyC5 0.031 0.033 0.04076.888 390 c-1,4-DiMcycloC6 0.081 0.084 0.10480.524 432 c-1,2-DiMcycloC6 0.044 0.045 0.05781.342 442 Propylcyclopentane 0.525 0.552 0.67681.712 450 1,1,3-TriMcycloC6 0.159 0.167 0.18289.018 568 t-1-E-4-M-cyC6? 0.226 0.232 0.25989.164 570 c-1-E-4-McyC6? 0.442 0.452 0.50691.551 608 1 -M-2-PcycloC5 0.384 0.396 0.43994.800 644 Propylcylohexane 0.271 0.278 0.31095.236 648 1-M-2-EcycloC6 0.757 0.763 0.86799.254 666 C10-Naphthene 0.756 0.764 0.779
101.717 692 t-1-M-2-propylcyC6? 0.166 0.167 0.171104.654 714 sec-Butylcyclohexane 1.502 1.501 1.548105.420 722 C10-Naphthene 0.880 0.883 0.906
Olefins 72.620 340 C8-Diolefin 0.089 0.102 0.11575.620 370 C8-Olefins 0.135 0.154 0.17482.155 452 C9-Olefins 0.285 0.320 0.32682.947 460 C9-Olefins 0.028 0.031 0.03284.133 482 C9-Olefins 0.099 0.111 0.11384.618 490 C9-Olefins 0.021 0.023 0.02485.941 508 C9-Olefin 0.099 0.111 0.11487.089 522 C9-Olefin 0.041 0.046 0.04788.428 560 C9-Olefin 0.024 0.026 0.02789.984 575 1-Nonene 0.073 0.082 0.08490.763 590 cis-3-Nonene 0.048 0.053 0.05591.898 610 C10-Olefin 0.122 0.136 0.12692.872 618 cis-2-Nonene 0.328 0.362 0.37593.103 624 C9-Olefin 0.296 0.327 0.33895.665 650 C10-Olefin 0.119 0.131 0.12296.463 654 C10-Olefin 0.103 0.114 0.10699.733 670 C10-Olefin 0.263 0.289 0.271
Paraffin 56.971 200 n-Heptane 0.043 0.051 0.06277.045 400 n-Octane 0.504 0.586 0.63891.079 600 n-Nonane 2.558 2.908 2.882
102.207 700 n-Decane 5.041 5.639 5.121
115
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Components by Group
Recovery = 100.00
Group Time Component %Wgt %Vol %MolParaffin 111.208 800 n-Undecane 4.720 5.208 4.365
118.012 895 n-Dodecane 3.798 4.140 3.223123.481 945 n-Tridecane 3.061 3.306 2.400128.092 965 n-Tetradecane 1.722 1.842 1.254132.141 980 n-Pentadecane 0.424 0.448 0.288135.818 985 n-Hexadecane 0.103 0.109 0.066
OxygenatesUnidentified 14.671 Unidentified 0.002 0.003 0.004
74.922 Unidentified 0.048 0.051 0.06280.123 Unidentified 0.015 0.016 0.01682.510 Unidentified 0.036 0.041 0.04182.823 Unidentified 0.028 0.032 0.03285.750 Unidentified 0.021 0.023 0.02486.313 Unidentified 0.015 0.017 0.01788.315 Unidentified 0.051 0.057 0.05889.801 Unidentified 0.041 0.045 0.04792.122 Unidentified 0.013 0.014 0.01393.649 Unidentified 0.104 0.107 0.10794.541 Unidentified 0.076 0.079 0.08794.685 Unidentified 0.077 0.080 0.08894.983 Unidentified 0.068 0.076 0.06995.388 Unidentified 0.184 0.185 0.21095.546 Unidentified 0.083 0.092 0.08696.589 Unidentified 0.044 0.041 0.05397.966 Unidentified 0.122 0.135 0.12499.045 Unidentified 0.071 0.078 0.07299.361 Unidentified 0.123 0.124 0.12799.439 Unidentified 0.175 0.195 0.178
100.470 Unidentified 0.444 0.414 0.534101.138 Unidentified 0.067 0.069 0.068101.386 Unidentified 0.058 0.064 0.059101.518 Unidentified 0.019 0.020 0.019102.508 Unidentified 0.040 0.045 0.037102.721 Unidentified 0.108 0.120 0.100102.968 Unidentified 0.091 0.083 0.109103.066 Unidentified 0.067 0.061 0.080103.452 Unidentified 0.161 0.178 0.149104.013 Unidentified 0.075 0.083 0.070104.203 Unidentified 0.086 0.073 0.105104.477 Unidentified 0.100 0.085 0.122104.928 Unidentified 0.044 0.048 0.040105.263 Unidentified 0.165 0.182 0.152106.380 Unidentified 0.163 0.154 0.175106.961 Unidentified 0.228 0.212 0.246107.528 Unidentified 0.195 0.183 0.210107.945 Unidentified 0.062 0.063 0.057108.798 Unidentified 0.098 0.100 0.090109.062 Unidentified 0.030 0.028 0.033
116
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Components by Group
Recovery = 100.00
Group Time Component %Wgt %Vol %MolUnidentified 109.377 Unidentified 0.158 0.163 0.146
109.648 Unidentified 0.136 0.125 0.147109.876 Unidentified 0.117 0.121 0.108109.988 Unidentified 0.142 0.147 0.131110.327 Unidentified 0.062 0.059 0.060110.506 Unidentified 0.310 0.284 0.334110.726 Unidentified 0.244 0.224 0.263110.987 Unidentified 0.119 0.110 0.116111.384 Unidentified 0.391 0.372 0.381111.588 Unidentified 0.211 0.221 0.179111.927 Unidentified 0.131 0.120 0.141112.303 Unidentified 0.122 0.132 0.103112.425 Unidentified 0.521 0.482 0.508112.995 Unidentified 0.216 0.201 0.211113.079 Unidentified 0.117 0.108 0.114113.254 Unidentified 0.153 0.143 0.149114.365 Unidentified 0.242 0.218 0.260114.525 Unidentified 0.111 0.105 0.108115.253 Unidentified 0.443 0.411 0.432115.512 Unidentified 0.462 0.492 0.392115.790 Unidentified 0.711 0.598 0.777116.533 Unidentified 0.203 0.188 0.197116.701 Unidentified 0.161 0.149 0.157117.642 Unidentified 0.127 0.113 0.113117.754 Unidentified 0.257 0.281 0.218117.871 Unidentified 0.201 0.219 0.170118.275 Unidentified 0.121 0.131 0.102118.468 Unidentified 0.285 0.264 0.277118.741 Unidentified 0.283 0.263 0.276118.855 Unidentified 0.059 0.056 0.053119.101 Unidentified 0.512 0.484 0.456119.322 Unidentified 0.129 0.120 0.126119.557 Unidentified 0.055 0.051 0.054119.818 Unidentified 0.157 0.146 0.153119.937 Unidentified 0.089 0.082 0.087120.068 Unidentified 0.364 0.344 0.324120.179 Unidentified 0.262 0.248 0.233120.553 Unidentified 0.671 0.621 0.597120.715 Unidentified 0.176 0.163 0.157120.838 Unidentified 0.214 0.198 0.190121.057 Unidentified 0.431 0.410 0.383121.162 Unidentified 0.471 0.449 0.419121.662 Unidentified 0.586 0.558 0.521121.790 Unidentified 0.213 0.202 0.189121.947 Unidentified 0.169 0.161 0.150122.036 Unidentified 0.504 0.480 0.449122.262 Unidentified 1.099 1.046 0.978122.406 Unidentified 0.173 0.164 0.154122.620 Unidentified 0.169 0.160 0.150
117
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Components by Group
Recovery = 100.00
Group Time Component %Wgt %Vol %MolUnidentified 122.835 Unidentified 0.158 0.129 0.160
123.206 Unidentified 0.570 0.466 0.580123.609 Unidentified 0.211 0.228 0.166123.711 Unidentified 0.094 0.101 0.074124.011 Unidentified 0.124 0.099 0.126124.142 Unidentified 0.300 0.240 0.305124.382 Unidentified 0.430 0.344 0.437124.484 Unidentified 0.574 0.459 0.583124.721 Unidentified 0.164 0.131 0.167124.792 Unidentified 0.087 0.070 0.088124.890 Unidentified 0.109 0.115 0.113124.970 Unidentified 0.073 0.077 0.075125.078 Unidentified 0.151 0.159 0.156125.233 Unidentified 0.395 0.418 0.407125.505 Unidentified 0.180 0.190 0.185125.633 Unidentified 0.206 0.217 0.212125.756 Unidentified 0.118 0.125 0.122125.904 Unidentified 0.668 0.705 0.688126.082 Unidentified 0.209 0.221 0.215126.198 Unidentified 0.104 0.110 0.107126.316 Unidentified 0.387 0.409 0.399126.535 Unidentified 0.537 0.437 0.496126.874 Unidentified 0.406 0.330 0.375127.059 Unidentified 0.159 0.129 0.147127.248 Unidentified 0.599 0.488 0.554127.403 Unidentified 0.083 0.068 0.077127.476 Unidentified 0.048 0.039 0.045127.565 Unidentified 0.068 0.056 0.063127.844 Unidentified 0.347 0.282 0.321128.246 Unidentified 0.108 0.115 0.078128.383 Unidentified 0.288 0.308 0.209128.475 Unidentified 0.161 0.172 0.117128.608 Unidentified 0.137 0.146 0.099128.706 Unidentified 0.060 0.049 0.056128.821 Unidentified 0.065 0.053 0.060128.873 Unidentified 0.086 0.070 0.079129.061 Unidentified 0.329 0.268 0.304129.236 Unidentified 0.237 0.193 0.219129.436 Unidentified 0.066 0.054 0.061129.545 Unidentified 0.039 0.032 0.036129.651 Unidentified 0.051 0.041 0.047129.743 Unidentified 0.040 0.032 0.037129.845 Unidentified 0.029 0.023 0.026129.960 Unidentified 0.114 0.093 0.105130.114 Unidentified 0.132 0.108 0.122130.210 Unidentified 0.079 0.064 0.073130.334 Unidentified 0.092 0.074 0.085130.386 Unidentified 0.058 0.047 0.054130.470 Unidentified 0.118 0.095 0.109
118
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Components by Group
Recovery = 100.00
Group Time Component %Wgt %Vol %MolUnidentified 130.565 Unidentified 0.127 0.103 0.118
130.812 Unidentified 0.362 0.292 0.334131.066 Unidentified 0.097 0.078 0.090131.218 Unidentified 0.014 0.011 0.012131.307 Unidentified 0.012 0.013 0.008131.455 Unidentified 0.045 0.048 0.031131.586 Unidentified 0.019 0.021 0.013131.768 Unidentified 0.007 0.008 0.005131.981 Unidentified 0.034 0.036 0.023132.398 Unidentified 0.009 0.010 0.006132.605 Unidentified 0.023 0.025 0.016132.789 Unidentified 0.009 0.009 0.006132.915 Unidentified 0.019 0.020 0.013133.311 Unidentified 0.018 0.019 0.012133.472 Unidentified 0.034 0.036 0.023133.713 Unidentified 0.025 0.026 0.017133.934 Unidentified 0.021 0.023 0.015134.014 Unidentified 0.012 0.013 0.008134.149 Unidentified 0.010 0.011 0.007134.344 Unidentified 0.055 0.058 0.035134.530 Unidentified 0.040 0.042 0.025134.843 Unidentified 0.017 0.018 0.011136.238 Unidentified 0.008 0.009 0.005137.658 Unidentified 0.014 0.014 0.008138.057 Unidentified 0.004 0.004 0.002139.235 Unidentified 0.023 0.024 0.013139.625 Unidentified 0.011 0.011 0.006
Plus
119
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Sample Chromatogram
C:\S
tar\data\2010\cgsbgo-10-665.cdf
128118
10898
8878
68 300 Toluene
475 Ethylbenzene500 m-Xylene502 p-Xylene
550 o-Xylene
616 Isopropylbenzene
651 Propylbenzene655 1-Ethyl-3-methylbenzene656 1-Ethyl-4-methylbenzene658 1,3,5-Trimethylbenzene
663 1-Ethyl-2-methylbenzene673 1,2,4-Trimethylbenzene
705 1,2,3-Trimethylbenzene708 1-M-4-isopropylbenzene712 2,3-Dihydroindene
718 1-M-2-isopropylbenzene724 1,3-Diethylbenzene725 1-M-3-propylbenzene727 1-M-4-propylbenzene728 Butylbenzene729 3,5-DM-1-Ebenzene730 1,2-Diethylbenzene?736 C10-Aromatic740 1-M-2-propyl benzene
756 1,4-DM-2-Ebenzene758 1,3-DM-4-Ebenzene764 1,2-DM-4-Ebenz+C1indan768 1,3-DM-2-Ebenzene785 1,2-DM-3-ethylbenzene790 1-E-2-isopropylbenzene806 1,2,4,5-TetraMbenzene810 1,2,3,5-TetraMbenzene822 1-tert-B-2-methylbenzen826 1-Ethyl-2-propylbenzene828 C11-Aromatic830 C11-Aromatic832 C11-Aromatic834 1-Methyl-3-butylbenzene836 1,2,3,4-TetraMbz+C11aro842 C11-Aromatic844 C11-Aromatic846 C11-Aromatic850 1,2,3,4-Tetrahydronapht858 Naphthalene865 C11-Aromatic884 C11-Aromatic890 1,3-Dipropylbenzene905 C11-Aromatic 910 1,3,5-Triethylbenzene915 C11-Aromatic?920 C11-Aromatic925 1-t-B-4-ethylbenzene930 1,2,4-Triethylbenzene
935 1-M-4-pentylbenzene940 Hexylbenzene 942 2-Methylnaphthalene
947 1-Methylnaphthalene
120
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Sample Chromatogram
C:\S
tar\data\2010\cgsbgo-10-665.cdf
128118
10898
8878
68
400 n-Octane
600 n-Nonane
700 n-Decane
800 n-Undecane
895 n-Dodecane
945 n-Tridecane
965 n-Tetradecane
980 n-Pentadecane
121
Appendix A
Part II:
Jet Fuels Thermophysical Properties
Fuels are:
A: Sasol CTL
B: Shell GTL
C: 50 vol.% Shell GTL + 50 vol.% Naphthenic compounds
D: 80 vol.% Shell GTL + 20 vol.% Hexanol
E: Jet A-1
122
TPRL 4453
Thermophysical Properties of Jet Fuel
A Report to University of Toronto
by
J. Gembarovic and J. Freeman
February 2010
TPRL, Inc. 3080 Kent Avenue
West Lafayette, IN 47906 Phone: 765-463-1581
Fax: 765-463-5235
WWW.TPRL.COM
123
Thermophysical Properties of Jet Fuel
INTRODUCTION
Five jet fuel samples, identified as A, B, C, D, and E were submitted for
thermophysical properties determination. Specific heat (Cp) was measured using the
DSC. Heated probe technique was used for the thermal conductivity (λ) measurement.
Specific heat is measured using a standard Perkin-Elmer Model DSC-2
Differential Scanning Calorimeter with sapphire as the reference material (ASTM E-
1269). The standard and sample were subjected to the same heat flow as a blank and the
differential powers required to heat the sample and standard at the same rate were
determined using the digital data acquisition system. From the masses of the sapphire
standard and sample, the differential power, and the known specific heat of sapphire, the
specific heat of the sample is computed. The experimental data are visually displayed as
the experiment progresses. All measured quantities are directly traceable to NIST
standards.
In the heated probe method (ASTM Standard D-5334), which may be considered
as a variant of the hot wire method, the line source and temperature sensor are combined
in one small diameter probe. This probe is inserted into the sample and the heater turned
on for a preselected time interval. During this time interval, the rate of heating of the
probe is measured. This heating quickly becomes semi-logarithmic and from this rate, the
thermal conductivity (k) of the sample is calculated.
RESULTS AND DISCUSSION
Specific heat results are listed in Table 1 and plotted in Figure 1. Total relative
expanded uncertainty (coverage factor k = 2) of the specific heat measurement is ± 3 %.
Heated probe apparatus was checked by an internal standard - glycerol, and the
thermal conductivity results were within 1 % of the expected value. The samples were
tested in air at normal pressure. The thermal conductivity results are given in Table 2.
Several measurements were made and average values and standard deviations are
reported. Total relative expanded uncertainty (k = 2) of the thermal conductivity
measurement is ± 7 %.
124
2
Table 1 Specific Heat Results
T/C
A B C D E
23 1.95 2.13 2.00 2.35 1.91
40 2.02 2.24 2.10 2.41 2.00
60 2.11 2.34 2.21 2.46 2.09
80 2.19 2.39 2.29 2.48 2.17
100 2.26 2.45 2.35 2.51 2.23
Cp / (J/g K)
Table 2 Thermal Conductivity Results
T/C
A B C D E
23 0.138 0.149 0.127 0.145 0.140
23 0.133 0.149 0.134 0.147 0.137
23 0.133 0.147 0.130 0.147 0.135
Average 0.135 0.148 0.130 0.146 0.137
STDEV 0.003 0.001 0.004 0.001 0.003
Thermal Conductivity / (W/m K)
1.7
1.8
1.9
2.0
2.1
2.2
2.3
2.4
2.5
2.6
20 30 40 50 60 70 80 90 100 110
T/C
Cp /
(J/g
K)
A
B
C
D
E
Figure 1 Specific Heat
125
Mass Conservation
Total mass is conserved in this system. Therefore, the difference between mass in and out of the
control volume is the rate at which mass accumulates within the control volume; i.e., general
form of conservation of mass can be expressed as,
∂ρ∂t + ∇. �ρv�� = 0 �D. 1�
or can be expanded as,
∂ρ∂t + 1
r∂�ρrv��
∂r + 1r
∂�ρv��∂θ + ∂�ρv��
∂z =0 �D. 2� where ρ, t and v are the fluid density, time and velocity. Since the system is at steady state and
there is no variation of speed in θ direction (v� = 0), the equation above can be simplified to,
1r
∂�v�r�∂r + ∂v�∂z =0 (D.3)
Conservation of Momentum
The conservation of momentum can be expressed in both axial and radial direction. The
derivation of simplified axial momentum equation is shown below.
ρ �∂v�∂t + v�∂v�∂r + v�r
∂v�∂θ + v�∂v�∂z � = − ∂P
∂z + ρg� + μ �1r
∂∂r �r ∂v�∂r � + 1
r�∂�v�∂θ� + ∂�v�∂z� �D. 4�
Assuming steady state (""# = 0), no pressure drop (∂P + $%&
� = 0), no variation in θ direction, and neglecting second derivative of v� with respect to z (small based on dimensional analysis),
equation above yields simplified form of the axial momentum equation,
v�∂v�∂z + v�
∂v�∂r = ν 1r
∂∂r �r ∂v�∂r � �D. 5�
138
where ν (= μ$) is the kinematic viscosity. On the left hand-side, z-momentum flows by axial and
radial convection are shown. Right hand-side represents viscous forces. Equation (D.5) is per
unit of volume.
Species Conservation
The continuity equation above defines the conservation of total mass, but it does not provide any
information of the chemical species (fuel, oxidizer and combustion products) present in the flow.
Species diffuse as a result of concentration gradients. The difference between summation of mass
flow of species i in both radial and axial directions, and the mass flow of species i due to
molecular diffusion in radial direction, is equal to net mass production rate of species i by
chemical reaction in that control volume. In mathematical formulation, that is [39]:
1r
∂�rρv�Y*�∂r + ∂�ρv�Y*�∂z − 1r
∂∂r +rρD*,
∂Y*∂r - = m/ *000 �D. 6� where m/ *000 is the net production rate of species i and Yi is the mass fraction of the ith species and
2 Y* = 1.3
*45
The binary diffusivity, Dij (m2/s), is the property of mixture and can be estimated for any two
species. In the above equation, the axial diffusion is neglected in comparison with radial
diffusion.
Energy Conservation
The energy equation is used to describe the temperature profile of chemically reacting flows. The
general form of thermal energy equation, originates from the first law of thermodynamics with
the assumption of steady state and ideal gas law for low Mach numbers (Ma<<1).
C7 �ρv�∂T∂r + ρv�
∂T∂z� = 1
r∂∂r �rλ ∂T
∂r� + ∂∂z �λ ∂T
∂z� −
2 +ρC7,*Y* �v*,�∂T∂r + v*,�
∂T∂z�-
*
*45− 2 h*W*ω/ *
*
*45+ q�?@ �D. 7�
139
where CP is the constant pressure heat capacity, λ is thermal conductivity. The h*, W* and ω/ * are the enthalpy of formation, molecular weight and net molar production rate of the ith species,
respectively. The left hand-side of the equation above indicates the thermal energy convection by
the temperature gradient in the element. The first two terms on right hand-side of equation
represents the contribution of thermal heat conduction based on Fourier’s law. The third term,
which includes, vB*, the diffusion velocity of the ith species (in r- and z-directions), shows the contribution of thermal diffusivity on thermal energy. The term, ∑ h*W*ω/ ***45 , is the heat
released from all chemical reactions in which the ith species participated. The last term is
associated to the radiation heat transfer from the element.
140