EXPERIMENTAL STUDIES ON THERMOCHEMICAL GASIFICATION OF HIGH LIGNIN BIOMASS
(PONGAMIA RESIDUE)
LALTA PRASAD
DEPARTMENT OF MECHANICAL ENGINEERING INDIAN INSTITUTE OF TECHNOLOGY DELHI
FEBRUARY 2015
© Indian Institute of Technology Delhi (IITD), New Delhi, 2015
EXPERIMENTAL STUDIES ON THERMOCHEMICAL GASIFICATION OF HIGH LIGNIN BIOMASS
(PONGAMIA RESIDUE)
by
LALTA PRASAD
Department of Mechanical Engineering
Submitted
In fulfilment of the requirements of the degree of
DOCTOR OF PHILOSOPHY to the
Indian Institute of Technology Delhi
February 2015
Dedicated to my Father
Late Shri Kanchhi Lal and My Family
i
CERTIFICATE
This is certify that the thesis entitled, “Experimental Studies on Thermochemical Gasification of High Lignin Biomass (Pongamia Residue)”, being submitted by Mr. Lalta Prasad to the Indian Institute of Technology Delhi, India, for award of degree of Doctor of Philosophy is a record of the bonafide research work carried out by him. He has worked under our guidance and supervision and has fulfilled the requirements for the submission of this thesis, which to our knowledge has reached the requisite standard.
The results contained in the thesis have not been submitted, in part or full, to any other university or institute for the award of any degree or diploma.
Dr. P.M.V. Subbarao Dr. J.P. Subrahmanyam
Professor Professor (Retd.)
Department of Mechanical Engineering Department of Mechanical Engineering Indian Institute of Technology Delhi, Indian Institute of Technology Delhi, New Delhi-110 016 (INDIA) New Delhi-110 016 (INDIA)
Date:
New Delhi
ii
ACKNOWLEDGEMENTS
I convey my deepest gratitude to my Research Supervisors Professor P.M.V.
Subbarao and Professor J.P. Subrahmanyam for their inspiring guidance, interest, constant encouragement and teaching me to make my own research decisions throughout my research work. I am indebted to them for their concern, skills and sincerity, drafting and presentation I acquired during my long association with them, which has brought this work in completion.
I am grateful to Prof. M.R. Ravi, Prof. Sangeeta Kohli, Prof. Anjan Ray, Prof. S.R.
Kale, Dr. Prabal Talukdar and Dr. B. Premchandran, Dept. of Mechanical Engineering; Prof.
V.K. Vijay and Prof. S.N. Naik of the Centre for Rural Development and Technology for their kind co-operation and help during my research work. I thank Prof. Bhuvanesh Gupta, Dept. of Textile Engineering for providing the necessary facilities for carrying out the TGA study.
I would like to thank Mr. Raj Kumar who helped me during the experimental work in Micro Model Complex. I would like to thank Micro Model staff: Mr. Birendar and Mr. Badri Prasad, IC Engine Lab staff: Mr. Kuldeep Singh (Sr. Superintendent), and Mr. Joginder who helped for overhaul the engine. I also appreciate the help provided by Mr. Shiv Kumar Upadhyay, Dept. of Chemical Engineering, Mr. P.S. Negi (Sr. Superintendent), Thermal Science Lab during the experimental work.
I am grateful to my fellow researchers in the Dept. of Mechanical Engineering Mr.
Virendra Kumar, Mr. Vinayak Hemadri, Mr. Kailash B. Suthar, Mr. Pranab Das, Mr.
Dushyant Kumar, Mr. S.K Soni, Mr. Amit Arora and Mr. Sachchit Majhi. Dept. of Chemical Engineering for their help, support and friendship without which, I could not have completed this work.
iii
I thank Principal Secretary, Mr. Rakesh Sharma (IAS), Technical Education Uttarakhand Government for permitting me to carry out my PhD work under QIP scheme.
The financial assistance received from the MHRD, under QIP scheme is also gracefully appreciated.
Last but not the least, I express my gratitude to my elders, in particular to my parents and in-laws Mr. & Mrs. P.S. Verma, to my dearest wife Pinky and my little daughters Rushali and Luvisha, who provided inspiration and constant support all along. I am indebted to them for all the sacrifices made to make my effort a success.
Lalta Prasad
iv
ABSTRACT
The present research work deals with the thermochemical gasification of high lignin biomass (Pongamia shell). A thermogravimetric analysis of Pongamia residue (shell and de- oiled cake) was carried out from room temperature to 700oC at varying heating rate to understand the thermal decomposition characteristics and to determine the kinetic parameters like the activation energy and the pre-exponential factor.
Only Pongamia shells were tried for gasification in the downdraft wood gasifier. It was found that the gasified Pongamia shells blocked the gasifier because the gap between conical grate and inner wall of the reactor was small. The solid residue of unconverted pongamia shells was higher due to low bulk density of the Pongamia shells and small gap between conical grate and inner wall of the reactor.
Pongamia residue was pelletized to 17 mm and 11.5 mm diameters length in the range of 30-60 mm. The bulk density of the Pongamia residue pellets increased significantly.
These pellets were gasified in the downdraft gasifier. S-type thermocouples were used to measure the temperatures of preheating, drying, pyrolysis, oxidation and reduction zones of the gasifier. The performance of the gasifier was optimized by varying opening of number of air nozzles for Pongamia residue pellets.
The gasification efficiency of Pongamia shell pellets and Pongamia mixture pellets of 17 mm diameter (1:1 by mass) was nearly same, but for Pongamia de-oiled cake pellets, it was rather poor. The complete gasification of these pellets (17 mm diameter) could not be achieved.
A spark ignition engine (converted from diesel engine) when tested in the gasoline mode at constant speed of 1450 rev/min and compression ratio of 10:1 with spark timing of 20obTDC, it produced 3.12 kW. The maximum power output for producer gas operation was
v
2.214 kW, 2.497 kW and 2.485 kW for shell pellets, mixture pellets and de-oiled cake pellets with 17 mm diameters respectively.
The heat transfer analysis study on shell pellets of 17 mm and 11.5 mm diameter also suggested that the smaller diameter pellets are better for gasification.
The producer gas generated from Pongamia mixture pellets of 11.5 mm diameter has calorific value higher than with shell pellets of same diameter. The gasification efficiency was calculated to be 84%.
De-oiled cake pellets with 11.5 mm diameter were also gasified in the gasifier. But gasification of these pellets was not achieved because the gasified pellets formed lumps and results the chocking of flow.
Performance and emission characteristics of the engine 100% fuelled with producer gas were measured at a constant speed of 1450 rev/min and a varying spark timing of 20o, 25o, 30o, 35o and 40obTDC.
Performance and emission characteristics of the engine 100% fuelled with producer gas were measured at a constant speed of 1450 rev/min and varying spark timing. The maximum power output for producer gas generated with 11.5 mm diameter were 2.975 kW and 2.982 kW at optimal spark timing of 35obTDC and 30obTDC for shell pellets and mixture pellets respectively . The BSEC values for shell pellets were marginally lower than for mixture pellets at their optimal spark timings. The equivalence ratios for producer gas operation generated with 11.5 mm diameter pellets were nearly same at optimal spark timings. The concentrations of CO and NOx in the engine exhaust were significantly lower for the producer gas operation as compared to gasoline operation. Pongamia mixture pellets (1:1 by mass) may be used as a potential renewable energy source for rural applications.
vi
CONTENTS
Sl. No. Title Page No.
Certificate i
Acknowledgements ii
Abstract iv
Contents vi-xii
List of Figures xiii-xvii
List of Tables xviii-xix
Symbols and Abbreviations xx-xxiii
Chapter-1 Introduction 1-11
1.1 India Biofuel Scenario 1
1.2 Salient Features of Biodiesel Program in India 3
1.3 Biodiesel Production in India 5
1.4 Mass and Energy analysis of Pongamia Pinnata 7 1.4.1 Pongamia Pinnata Residue as a Bio-energy Resource 9
1.5 Organization of the Thesis 10
Chapter-2 Literature Survey 12-54
2.1 Introduction 12
2.2 Thermal Degradation of Biomass 12
2.2.1 Biomass Drying 13
2.2.2 Biomass Pyrolysis 14
2.2.3 Volatile Composition 23
vii
2.3 Gasification Technology 24
2.3.1 Gasification 25
2.3.2 Type of Gasifiers 26
2.3.3 Reactions in a Gasifier 28
2.3.4 Biomass Gasification 31
2.4 Biomass Gasification Effort in India 39
2.4.1 Biomass Gasification Plants in India 40
2.5 Gas Cooling and Cleaning System 41
2.5.1 Physical Methods of Tar Removal 42
2.5.2 Control of Operating Parameters 44
2.5.3 Thermal cracking 45
2.5.4 Catalytic cracking 45
2.5.5 Ni-based catalyst 46
2.6 Gasifier-Engine Systems 47
2.7 Conclusions from Literature Survey 52
2.8 Objectives of the Present Work 53
2.9 Work Elements 54
Chapter-3 Thermogravimetry Analysis of Pongamia Residue 55-81
3.0 Introduction 55
3.1 Thermogravimetric Analysis 56
3.2 Preparation of Samples and Selection of Experimental Conditions 57
3.3 Kinetic Modelling for TGA 59
3.3.1 The Differential Method 59
3.3.2 The Flynn-Wall-Ozawa (FWO) Method 61
viii
3.4 TGA Results for Pongamia Shells 62
3.5 TGA Results for Pongamia De-oiled Cake 68
3.6 TGA Results for Pongamia Mixture (Shell and De-oiled Cake) 74 3.7 Conclusions from TGA Study of Pongamia Residue 79
Chapter-4 Experimental Setup for Gasifier and Engine 82-100
4.0 Introduction 82
4.1 Description of Gasifier System 82
4.1.1 Reactor 84
4.1.2 Cooling and Cleaning System 84
4.1.3 Water Bubbler and Burner 86
4.2 Measuring Instruments 87
4.2.1 Temperature Measurement 87
4.2.2 Pressure Measurement 89
4.2.3 Gas Flow Rate Measurement 89
4.2.4 Gas Composition Measurement 90
4.2.5 Moisture Content Measurement 90
4.3 Experimental Setup for Engine 91
4.3.1 Engine Considered for Producer Gas Operation 92
4.3.2 Dynamometer 93
4.4 Basic Measuring Systems 93
4.4.1 Fuel Flow Measurement 93
4.4.2 Brake Specific Energy Consumption (BSEC) Measurement 94 4.4.3 Brake Mean Effective Pressure (BMEP) Measurement 94 4.4.4 Fuel Gas Composition Measuring System 95
ix
4.4.5 Air Flow Measuring System 95
4.4.6 Equivalence Ratio(ER) Calculation 96
4.4.7 Air Intake and Fuel Mixing System 97
4.4.8 Temperature Measuring System 97
4.4.9 Engine Speed Measuring System 97
4.4.10 Spark Timing 97
4.4.11 Emission Measurements 98
4.5 Experimental Procedure 98
4.5.1 Phase 1: Preliminary Tests with Gasoline 98
4.5.2 Phase II: Tests with Producer Gas 99
4.5.3 Procedure for Operating Gasifier-Engine System 99
Chapter-5 Pelletization of Pongamia Residue 101-128
5.0 Biomass Pelletization Scenario 101
5.1 Pelletization of Pongamia Residue 102
5.2 Analysis of Heat Transfer in Pellets of Pongamia Shells 109 5.2.1 Heat Transfer around a Circular Cylinder for Cross Flow 109
5.2.2 Transient Heat Conduction 110
5.2.3 Experimental Setup and Procedure for Heat Transfer Analysis 113
5.2.4 Data Reduction and Analysis 114
5.3 Heat Transfer Analysis Calculations 114
5.3.1 Pongamia Shell Pellets (17 mm diameter) 114 5.3.2 Pongamia Shell Pellets (11.5 mm diameter) 118 5.4 Fabrication of New Die Plate for 11.5 mm Pellets 123 5.5 Conclusions from Pelletization of Pongamia Residue 127
x
5.6 Conclusions from Heat Transfer Analysis of SP (17 mm and 11.5 mm diameter) 127
Chapter-6 Gasification of Pongamia Residue Pellets 129-157
6.0 Downdraft Wood Gasifier 129
6.1 Calculation for Operating Parameters of the Gasifier 133
6.2 Performance of Gasifier 135
6.2.1 Pongamia Shell Pellets (17 mm diameter) Gasification 136 6.2.2 Pongamia De-oiled Cake Pellets (17 mm diameter) Gasification 139 6.2.3 Pongamia Mixture Pellets (17 mm diameter) Gasification 142 6.3 Pongamia Residue Pellets (11.5 mm diameter) Gasification 144
6.3.1 Pongamia Shell Pellets 144
6.3.2 Pongamia De-oiled Cake Pellets 147
6.3.3 Pongamia Mixture Pellets (3:1 by mass) 149 6.3.4 Pongamia Mixture Pellets (1:1 by mass) 150 6.4 Pressure Measurement across the Gasifier System 153 6.5 Conclusions from Pongamia Residue Pellets Gasification 154
Chapter-7 Engine Performance Tests 158-179
7.0 Introduction 158
7.1 Behaviour of Producer Gas Engine System Running with Large Diameter Pellets 158
7.1.1 Effect of BMEP on BSEC 159
7.1.2 Effect of BMEP on Exhaust Gas Temperature 160
7.1.3 Effect of BMEP on NOxEmissions 161
7.1.4 Effect of BMEP on Carbon Monoxide Emissions 161 7.1.5 Effect of BMEP on Hydrocarbons Emissions 162
xi
7.2 Results of the Engine Performance on Producer Gas Generated from SP
of 11.5 mm Diameter 163
7.2.1 Effect of BMEP on BSEC at Different Spark Timings 164 7.2.2 Effect of BMEP on Equivalence Ratio at Different Spark Timings 164 7.2.3 Effect of BMEP on Exhaust Gas Temperature at Different Spark Timings 165 7.2.4 Effect of Spark Timings on Maximum BMEP 166 7.2.5 Effect of BMEP on NOx Emissions at Different Spark Timings 166 7.2.6 Effect of BMEP on Carbon Monoxides Emissions at Different
Spark Timings 167
7.2.7 Effect of BMEP on Hydrocarbon Emissions at Different Spark Timings 167 7.3 Results of the Engine Performance on Producer Gas Generated from MP (1:1 by
mass) of 11.5 mm Diameter 169
7.3.1 Effect of BMEP on BSEC at Different Spark Timings 169 7.3.2 Effect of BMEP on Equivalence Ratio at Different Spark Timings 170 7.3.3 Effect of BMEP on Exhaust Gas Temperature at Different Spark Timings 170 7.3.4 Effect of Spark Timings on Maximum BMEP 171 7.3.5 Effect of BMEP on NOx Emissions at Different Spark Timings 172 7.3.6 Effect of BMEP on Carbon Monoxide at Different Spark Timings 172 7.3.7 Effect of BMEP on Hydrocarbon Emissions at Different Spark Timings 172
7.4 Comparison of BSEC 173
7.5 Compassion of Equivalence Ratios 174
7.6 Problems Encountered During Operation of the Gasifier-Engine System 176 7.7 Conclusions from Engine Performance Runs on Producer Gas 177
xii
Chapter-8 Conclusions 180-183
8.0 Overall Conclusions 180
8.1 The novelty of the present work 182
8.2 Recommendations for Future Work 183
REFERENCES 184-199
APPENDIX 200-210
RESEARCH PUBLICATIONS 211
AUTHOR BIOGRAPHY 212
xiii
LIST OF FIGURES
Figure No. Page No.
1.1 Pongamia Fruit Mass Distribution 7
1.2 Energy Content in Sub species of Pongamia Fruit Seed as Biodiesel Feedstock
8
2.1 Types of Fixed-bed Gasifiers 27
2.2 Schematic Diagram of a Downdraft Gasifier 28 2.3 Profiles of Temperature and Relative Mass of Lignin: (a) 1 K/s (b) 100K/s 36 2.4 Gas Evolution Rate from Lignin with a Heating Rate of 1 K/S During (a)
Pyrolysis (b) Steam Gasification
36
2.5 Cumulative Gas Yield vs. Temperature for Lignin: (a) CO (b) CO2 37 3.1 Control Volume Surrounding the Decomposing Material in TGA 57 3.2 Comparison of TGA Curves for Pongamia Shell at Different Heating Rates
(HR)
63
3.3 Comparison of DTGA Curves for Pongamia Shell at Different Heating Rates (HR)
64
3.4 Comparison of DTGA Curves for Pongamia Shell at Different Heating Rates (HR)
64
3.5 Plots of ln(dα/dt) Versus 1/T using Differential Method (Eq. 3.10) for Pongamia Shell
66
3.6 Plots of logβ Versus 1000/T using the Flynn-Wall-Ozawa (FWO) Method (Eq. 3.11) for Pongamia Shell
66
3.7 Calculated Activation Energies at Different Conversions for Pyrolysis of Pongamia Residue (Shell) by using FWO and Differential Methods
67
3.8 Comparison of TGA Curves for Pongamia De-oiled Cake at Different Heating Rates (HR)
69
3.9 Comparison of DTGA Curves for Pongamia De-oiled Cake at Different Heating Rates (HR)
70
xiv
3.10 Comparison of DTGA Curves for Pongamia De-oiled Cake at Different Heating Rates (HR)
71
3.11 Plots of ln(dα/dt) Versus 1/T using Differential Method (Eq. 4.10) for Pongamia De-oiled Cake
72
3.12 Plots of logβ Versus 1000/T using the Flynn-Wall-Ozawa (FWO) Method (Eq. 3.11) for Pongamia De- oiled cake
72
3.13 Calculated Activation Energies at Different Conversions for Pyrolysis of Pongamia Residue (De-oiled Cake) by using FWO and Differential Methods
73
3.14 Comparison of TGA Curves for Pongamia Mixture at Different Heating Rates (HR)
75 3.15 Comparison of DTGA Curves for Pongamia Mixture at Different Heating
Rates (HR)
75
3.16 Comparison of DTGA Curves for Pongamia Mixture at Different Heating Rates (HR)
77
3.17 Plots of ln(dα/dt) Versus 1/T using Differential Method for Pongamia Mixture
77
3.18 Plots of logβ Versus 1000/T using the Flynn-Wall-Ozawa (FWO) Method for Pongamia Mixture
78
3.19 Calculated Activation Energies at Different Conversions for Pyrolysis of Pongamia Mixture by using FWO and Differential Methods
78
4.1 Schematic Diagram of NETPRO I.I.Sc-DASAG Downdraft Gasifier 83
4.2 Water Spray System for Gas Cooling 85
4.3 Rusted (old) Sand Bed Filter 86
4.4 New Sand Bed Filters (a) Top View Opened (b) Front View 86
4.5 Details of S-Type Thermocouples 88
4.6 Location of the Thermocouples from the Top of the Reactor 89
4.7 Overall view of the Experimental Setup 92
4.8 Single Cylinder Producer Gas Spark Ignition Engine 93
4.9 Arrangement for Changing Spark Timing 98
5.1 Photograph of Pongamia Shells after Decortications 103
xv
5.2 Photograph of Hammer Mill 103
5.3 Photograph of Pelletizing Machine 103
5.4 Photographs of Original Die Plate 104
5.5 Photograph of SP (17 mm diameter) 106
5.6 Photograph of DOCP (17 mm diameter) 107
5.7 Photograph of Pongamia MP (17 mm diameter) 108 5.8 Engineering Drawing of SP with four thermocouples 113 5.9 Experimental set up for Heat Transfer Analysis of Pellet 113 5.10 Variation of the Specific Heat Vs λn for Different Temperatures and Time
for 17 mm pellet
115
5.11 Enlarged view of the previous Figure 5.10 115 5.12 Variation of Temperature at the Centre of the Pellet with Time 116 5.13 Variation of Thermal Conductivity of the Pellet with Time 116 5.14 Variation of Specific Heat Capacity of the Pellet with Time 117 5.15 Variation of the Specific Heat Vs λn for Different Temperate and Time for
11.5 mm pellet
118
5.16 Enlarge view of the previous Figure 5.15 119 5.17 Variation of Temperature at the Centre of the Pellet (11.5 mm) with Time 119 5.18 Variation of Thermal Conductivity and Thermal Conductivity of the Pellet
(11.5 mm diameter) with Time
120
5.19 Photographs of Die Plates Hole Diameter 12 mm 124
5.20 Photograph of SP (11.5 mm diameter) 125
5.21 Photograph of DOCP (11.5 mm diameter) 126
5.22 Photograph of MP (11.5 mm diameter) 126
6.1 Photographic View of the 20kWe Downdraft Gasifier 131 6.2 Temperature Variations in Various Zones of the Gasifier with time, after
15 minutes of Flaring
136
xvi
6.3 Temperature Variations in Various Zones of the Gasifier with time, after 15 minutes of Flaring
140
6.4 Temperature Variations in Various Zones of the Gasifier with time, after 15 minutes of Flaring
143
6.5 Temperature Variations in Various Zones of the Gasifier with time, after 15 minutes of Flaring
145
6.6 Flame from the Burner for Shell Pellets Gasification 146 6.7 Variation of Fuel Gas Compositions with time for Shell Pellets
Gasification
146 6.8 Variation of Calorific Value of the Producer Gas with time for Shell Pellets 147 6.9 Flame from the Burner for DOCP Gasification 148 6.10 Lumps Formed during Gasification of the DOCP 148 6.11 Variation of Fuel Gas Compositions with time for MP (3:1 by mass) 149 6.12 Temperature Variations in Various Zones of the Gasifier with time, after
15 minutes of Flaring
151
6.13 Variation of Fuel Gas Compositions with time for MP Gasification 151 6.14 Variation of Calorific Value of the Producer Gas with time for MP 152 6.15 Flame from the Burner for MP (1:1 ratio) Gasification 152 6.16 Pressure across the Exit of the Fine Filter for MP (1:1 ratio) 154 7.1 Comparison of BSEC of Engine at Different BMEP Conditions 159 7.2 Comparison of Exhaust Gas Temperature at Different BMEP Conditions 160 7.3 Comparison of NOx Emissions at Different BMEP Conditions 161 7.4 Comparison of Carbon Monoxide Emissions at Different BMEP
Conditions
162
7.5 Comparison of Hydrocarbon Emissions at Different BMEP Conditions 162 7.6 Effect of BMEP on BSEC at Different Spark Timings 164 7.7 Effect of BMEP on Equivalence Ratio at Different Spark Timings 165 7.8 Effect of BMEP on Exhaust Gas Temperature at Different Spark Timings 165
xvii
7.9 Effect of Spark Timings on Brake Mean Effective Pressure (BMEP) 165 7.10 Effect of BMEP on NOx Emissions at Different Spark Timings 167 7.11 Effect of BMEP on Carbon monoxide Emissions at Different Spark
Timings
168
7.12 Effect of BMEP on Hydrocarbon Emissions at Different Spark Timings 168 7.13 Effect of BMEP on BSEC at Different Spark Timings 169 7.14 Effect of BMEP on Equivalence Ratio at Different Spark Timings 170 7.15 Effect of BMEP on Exhaust Gas Temperature at Different Spark Timings 171
7.16 Effect of Spark Timings on BMEP 171
7.17 Effect of BMEP on NOx Emissions at Different Spark Timings 172 7.18 Effect of BMEP on Carbon Monoxide Emissions at Different Spark
Timings
173
7.19 Effect of BMEP on Hydrocarbon Emissions at Different Spark Timings 173 7.20 Comparison of BSEC for Maximum Power Output Condition 174 7.21 Effect of BMEP on Equivalence Ratio at Different Spark Timings 175 7.22 Tar Deposits on (a) Coarse Filter Material (b) Fine Filter Material 177
xviii
LIST OF TABLES
Table No. Page No.
1.1 Blending of Bio fuels in some Selected Countries 2 1.2 Mass and Energy Analysis of Pongamia Feedstock in Biodiesel Conversion 8
2.1 Gasifiers Recently Developed in India 40
2.2 The State -Wise/ Year-Wise List of Commissioned Biomass Power/Co- Generation Projects in India
41
2.3 Gas Quality Requirement for Power Generation 42 2.4 Typical Levels of Tar in Biomass Gasifier by Type 42 2.5 Reduction of Particles and Tars in Various Producer Gas Cleaning Systems 44 3.1 Proximate Analysis of Pongamia Residue (% as wet basis) 58 3.2 Ultimate Analysis of Pongamia Residue (% as air dried basis) 58 3.3 Average Structural Analysis of Biomass Materials 58 3.4 Thermal Degradation Temperature of Pongamia Residue (Shell) 65 3.5 Activation Energy of Various Biomass Materials Reported in Literature 68 3.6 Thermal Degradation Temperature of Pongamia De-oiled cake 70 3.7 Activation Energy of Various Biomass Materials Reported in Literature 74 3.8 Thermal Degradation Temperature of Pongamia Mixture (1:1 by mass ratio) 76 5.1 Constants of Equation 5.2 for the Circular Cylinder in Cross flow 110 5.2 Comparison of Thermal Properties of Pongamia shell Pellets with other
Materials
121
5.3 Numerical Value of Transient Heat Equation for Various Times 122 5.4 Comparison of power consumption and surface temperature of pelletization
machine for Pongamia shell Pellets
124
5.5 Bulk Density of Pongamia Residue Pellets 127
xix
6.1 Comparison of Producer Gas Composition (%) from Various Biomass Materials
131
6.2 Maximum Temperature Measured in Oxidation and Reduction Zones 132
6.3 Calorific Value of Compounds 134
6.4 Parameters of Producer Gas Calculated for Biomass Gasification in Downdraft Wood Gasifier
139
6.5 Parameters of Producer Gas Calculated for Biomass Gasification in Downdraft Wood Gasifier (using 17 mm diameter pellets)
142
6.6 Parameters of Producer Gas Obtained for Pongamia Residue Pellets Gasified in Downdraft Wood Gasifier
153
7.1 Base Line Operating Condition of the Spark Ignition (SI) Engine 158 7.2 Comparison of the Engine Parameters obtained for Pongamia Residue
Pellets of 11.5 mm diameter
176
8.1 Comparison of the Engine Parameters obtained for Pongamia Residue Pellets of 11.5 mm diameter
180
xx
Symbols and Abbreviations Common Notations
A Pyrolysis temperature, K E Activation Energy, kJ/mol k Pyrolysis rate constant, 1/s m Weight of sample at time, t, mg mi Initial weight of sample, mg mf final weight of sample, mg n reaction order
R universal gas constant = 8.314 J g/mol K Xc Char fraction
t pyrolysis time,
oC Degree Centigrade hw
' Manometers differential height (mm)
Cth Coefficient of Thermal Conversion or Gasification Efficiency P Power output (kW)
n no. of revs per power stroke (2 for 4 stroke) Dv Displacement volume (m3)
Cd Discharge coefficient of hole air drum (0.62) Ua Density of air at 1 atm. and 25 0C (1180 g/m3)
Uw Density of water at 1 atm. and 25 0C (1000 kg/m3)
stoic a f
m m ¸¸
¹
·
¨¨
©
§
x x
Stoichiometric fuel-air ratio
xxi
Actual a f
m m ¸¸
¹
·
¨¨
©
§
x x
Actual fuel-air ratio
x
ma Mass flow rate of air (g/s)
x
mf Mass flow rate of fuel (g/s) MWair Molecular Weight of Air
MWg Molecular Weight of Producer Gas Eg Energy Released per Kilogram of Fuel
QCVg Calorific value of Producer Gas (MJ/Nm3) QCVFuel Calorific value of Fuel Biomass (MJ/kg) d Diameter of cylindrical pellet (mm) r Radius of cylinder(mm)
Nu Nusselt number Pr Prandtl number Re Reynolds number Bi Biot number
T1 Ambient temperature for the first case (oC) T2 Hot air temperature for first case (oC)
T3 Ambient temperature for the second case (oC) T4 Hot air temperature for the second case (oC) Cp Specific heat capacity
t time(s)
h Heat transfer coefficient(W/m2K) k1 Thermal conductivity of air (W/mK)
k2 Thermal conductivity of Pongamia shell(W/mK)
xxii v Velocity of air(m/s)
Abbreviations
TGA Thermogravimetric Analysis
DTGA Differential Thermogravimetric Analysis TR Temperature Range
PT Peak Temperature FWO Flynn-Wall-Ozawa
BMEP Brake Mean Effective Pressure, kN/m2 BSFC Brake Specific Fuel Consumption, (g/kWh) bTDC Before Top Dead Centre
CO Carbon Monoxide HC Unburnt Hydrocarbon NOx Oxides of Nitrogen TDC Top Dead Centre Rg Producer Gas Constant
Patm Atmospheric pressure =101325 N/m2 SP Pongamia Shell Pellets
MP Pongamia Mixture Pellets DOCP Pongamia De-Oiled Cake Pellets
Greek Letters
α Conversion Fraction of the Mass Reacted in Time, t β Heating rate (oC/min)
ρg Density of Producer Gas(kg/m3) Φ Equivalence ratio
xxiii
~ Approximately
μ Dynamic viscosity of air(m2/s) Θ Dimensionless temperature Jo, J1 Bessel functions
τ Fourier number
