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STUDIES ON STORAGE STABILITY OF BIO-DIESEL AND ITS UTILISATION IN A DIESEL ENGINE
by
DILIP KUMAR BORA Centre for Energy Studies
Submitted
in fulfillment of the requirements of the degree of Doctor of Philosophy
to the
INDIAN INSTITUTE OF TECHNOLOGY, DELHI
APRIL 2008
CERTIFICATE
This is to certify that the thesis entitled, "STUDIES ON STORAGE STABILITY OF BIO-DIESEL AND ITS UTILISATION IN A DIESEL ENGINE", being submitted by MR. DILIP KUMAR BORA to the Indian Institute of Technology Delhi, for the award 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.
Date: aq
Prof. L. M. Das
Centre for Energy Studies
Indian Institute of Technology Delhi New Delhi — 110016
India
e7n
Prof. M. M. K. Gajendra Babu Centre for Energy Studies Indian Institute of Technology Delhi New Delhi - 110016 India
ACKNOWLEDGEMENT
The first and foremost who needs to be recognized is the Almighty God. I would never be here if were not for Him. Even though He is unseen, I know His presence is always with me. He needs to be recognized due to the fact that too often He does go unacknowledged.
Next, I wish to express my unreserved gratitude to my supervisors, Prof. L.M.Das and Prof.M.K.Gajendra Babu for their valuable guidance, ever helping attitude, critical and encouraging comments throughout the completion of this research work. Their constructive criticisms and ideas have made this project worth reading. To say the least, I am very privileged to have them as my advisors.
Thanks are also due to my committee members, Prof. J.P. Subrahmanyam, Prof.S.C.Mullick and Prof.T.S.Bhatti. Their insightful suggestions and guidance are highly appreciated. I also want to thank them for joining the committee. It was a great honour for me to be recipient of professional and moral guidance of Dr.S.N.Naik and Prof. M.G.Dastidar throughout the research work. I am indeed thankful to Dr.R.K.Malhotra, IOCL, Faridabad for providing necessary guidance and help in experimental work.
I would like to thank all the staff at the Engines & Unconventional Fuel Lab.
Special word of thanks to Mr.G.P.Singh and Mr. Attar Singh for providing technical support during the experimentation work. I would also like to extend my sincere thank to Mr.Nabakrushna Behera and Mr. M. Senthil Kumar for the technical support guidance provided by them for the development of storage stability test setup. I thank Mr. Rakesh Kumar and Mr. Virendra Singh for their support durin experiments.
There are also some friends who have helped me along the way for the successful completion of this project and had given a good company during my stay at IIT Delhi. I take this opportunity to thank Mr. Bhargab Das, Dr. Yogesh Vishnu Agav, Dr.R.T.Naik,
Dr. Sunil Mahla, Mr. B. Baiju, Mr. Malaya Naik, Mr. Raghupati Karu, Mr. G. N. Kumar and Mr. Sudhir Ghai for their support and encouragement.
Due to the preoccupation with the priorities for the research project my parents, especially my beloved wife Rupanjali and my daughters Sowjanya and Pranayana who were deprived of the privileges and prerogatives which God has bestowed on them. Their patience and kind understanding and constant encouragement have always been a moral booster for me.
Lastly I would like to apologize to all those names, which do not figure here, but have helped me during the tenure of my research.
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New Delhi Dilip Kumar Bora
April 2008
ABSTRACT
Among several alternative fuels, biodiesel has been recognized as the one that has a significant potential for a diesel engine.
The biodiesel to be used in India will have to be obtained from non-edible sources and Karanja and Mahua oils recognized for this reason were chosen for the present studies. The biodiesel derived from Karanja and Mahua oils has been found to be good synergistic blending component with diesel as they enhanced properties like cetane rating, flash point. The poor properties of biodiesel linked to cold temperature flow do not create any problem for normal temperatures encountered in almost all over India.
Experimental test rig was developed to carry out engine performance, emission and combustion characteristic studies on selected fuel blends at different load conditions. On the basis of the results obtained during comprehensive engine testing, optimization of several engine operating parameters like different fuel injection pressures were carried out for various fuel blends. The engine performance studies have revealed that biodiesel even up to 20% has to some extent can lead to a better performance in respect of power output, thermal efficiency and emissions. However, NOx has a propensity to increase with the increase in biodiesel substitution in a direct injection diesel engine. As biodiesel proportion with diesel is increased, at higher fuel injection pressure, the performance, emission and combustion characteristics improve.
Although the commercial scenes for biodiesel have also grown, there remains some concern with respect to its resistance to oxidative degradation during storage. Due to the chemical structure of biodiesel the presence of the double bond in the molecule produce a higher level of reactivity with the oxygen, especially when it placed in contact with air. Consequently, storage of biodiesel over extended periods may lead to degradation of fuel properties that can compromise fuel quality. The present study used samples of biodiesel prepared by the process of transesterification from different
vegetable oils: karanja oil and mahua oil. These biodiesels are used to determine the effects of long time storage under different conditions on oxidation stability. Samples were stored in white (exposed) and amber (not exposed) plastic containers at room temperature. The study was conducted for a period of 12-months. At regular intervals, samples were taken to measure the following physicochemical quality parameters:
peroxide value (PV), viscosity (KV). Results showed that PV, KV increased with increasing storage time of biodiesel samples.
Karanja oil methyl ester (KOME) was used for long-term engine operations. A blend of 20 percent was selected as an optimum biodiesel blend. Two similar new engines were completely disassembled and subjected to dimensioning of several vital moving parts and then subjected to long-term endurance tests on 20 percent biodiesel blend and diesel oil, respectively. After completion of the test, both the engines were again disassembled for physical inspection and wear measurement of several vital parts.
The physical wear of several vital parts, injector coking, carbon deposits on piston, and ring sticking were found to be significantly lower in case of 20 percent biodiesel-fuelled engine. Various tribological tests on lubricating oil were conducted in order to correlate the comparative performance of the two fuels. Tribological tests confirmed substantially lower wear and thus have the potential to improve the life for biodiesel operated engines.
Hence it is concluded that biodiesel blending in diesel appears to be a more feasible option which can offer energy security, rural development and environmental protection in Indian scenario.
CONTENTS
Page No Certificate
Acknowledgements ii
Abstract iv
Contents vi
List of Figures xv
List of Plates xx
List of Tables xxiii
Nomenclature xxvi
Chapter:! INTRODUCTION 1- 76
L1 Background 1
1.1.1 Energy Scenario in India 4
1.1.2 International Scenario of Biodiesel 5 1.1.3 Biodiesel for Energy Security in India 9
1.1.4 Transport Scenario in India 11
1.1.5 Refineries Scenario in India 12
1.2 Need of Alternative and Renewable Fuel 13
1.2.1 Alternative Diesel Fuels 14
1.2.2 Triglyceride as Diesel Fuels 14
1.2.3 Structure of Vegetable Oils 15
1.2.4 Properties of Vegetable Oils as Fuel 17 1.2.5 Utilization of Vegetable Oils as Fuels 18 1.2.5.1 Use of Vegetable Oils as Diesel Fuel 18
1.2.5.2 Use of Biodiesel 19
vi
1.3 1.4 1.5
1.5.1
Non-Edible Oils for Producing Biodiesel Land Availability for Production of Biodiesel Process of Biodiesel Production: Chemistry of Transesterification Reaction
Variables Affecting Transesterification Process
20 23 23
26 1.5.1.1 Reaction Temperature 27 1.5.1.2 Molar ratio of alcohol to oil 28
1.5.1.3 Catalyst 30
1.5.1.4 Mixing Intensity 34
1.5.1.5 Purity of Reactants 35 1.5.1.6 Presence of moisture and free fatty
acid
35
1.5.1.7 Effect of reaction time 37 1.5.2 Other types of Transesterification 37 1.5.3 Transesterification using supercritical fluids 39
1.6 Chemical Composition of Biodiesel 39
1.7 Fuel Properties of Biodiesel 39
Storage Stability of Biodiesel 41 1.8.1 Effect of Storage Temperature 41
1.8.2 Effect of Antioxidants 42
1.8.3 Peroxide Levels 45
1.8.4 Viscosity 47
1.8.5 Composition 48
1.8.6 Free Fatty Acid Levels 48
1.8.7 Effect of Oxidation and Distillation on Cetane 49 Number
1.8.8 Acid Value 50
1.8.9 Density 51
1.8.10 Heat of Combustion 51
1.8.11 Iodine Number 51
1.8.12 Gum Number 52
vii
1.8.13 1.8.14 1.8.15
Flash Point Variation
Neutralization Value Variation Sediment
52 53 53 1.9 Economical Feasibility of Biodiesel Utilization 59
1.10 Rural Employment Opportunities 60
1.11 Environmental Considerations 61
1.12 CO2 Cycle for Biodiesel Fuel 61
1.13 Combustion Characteristics of Diesel Engine 63
1.13.1 Heat Release Rate Analysis 65
1.14 Tribological Studies on Lubricating Oil 67
1.15 Energy Content 75
Chapter: 2 LITERATURE REVIEW 77- 111
2.1 Introduction 77
2.2 Previous Studies 78
2.2.2 Storage Stability 89
2.2.3 Performance and Emission Characteristics 92
2.2.4 Combustion Studies 100
2.2.5 Endurance Tests 103
2.3 Major Unresolved Issues 109
2.4 Statement of the problem 110
Chapter: 3 TEST RIG DEVELOPMENT & 112-167
EXPERIMENTAL METHODOLOGY
3.1 Introduction 112
31 Fuel Development and Characterization 112
3.2.1 Density 118
3.2.2 Kinematic Viscosity 118
3.2.3 Flash Point 118
viii
3.2.4 Pour and Cloud Point 118
3.2.5 Cetane Number 119
3.2.6 Copper Strip Corrosion 119
3.2.7 Distillation 119
3.2.8 Acid value 120
3.2.9 Ash Content 120
3.2.10 Carbon Residue 120
3.2.11 Moisture Content 120
3.2.12 Sulphur 121
3.2.13 Phosphorus Content 121
3.2.14 Iodine Value 121
3.2.15 Saponification Value 122
3.2.16 Free Glycerin 123
3.2.17 Total glycerin 123
3.2.18 Calorific Value Determination 123 3.2.19 Preparation of Diesel -Biodiesel Blends 127 3.3 Engine Selection and Instrumentation 127 3.3.1 Development of Experimental Test Rig 128 3.3.1.1 Installation of the Instrument Control 130
Panel
3.3.1.2 Parameters Selection 132 3.3.2 Measurement Methods and Selection of Instruments 133
3.3.2.1 Brake Power 133
3.3.2.2 Engine Speed (RPM) 133
3.3.2.3 Crank Angle 134
3.3.2.4 Air Consumption 135
3.3.2.5 Fuel Consumption 136 3.3.2.6 Cylinder Gas Pressure 138 3.3.2.7 Computer Interfacing 139 3.3.2.8 Rate of Heat Release and Combustion 140
Characteristics
ix
3.3.2.9 Temperature Measurement 3.3.2.10 Exhaust Emission Analysis
142 142 3.3.3 Variation of Injection Pressure 144
3.4 Experimental Approach 145
3.4.1 Preliminary Runs 145
3.4.2 Long-term Endurance Test 146
3.4.3 Twelve Hours Rating Test 148
3.4.4 Wear Measurement of Vital Parts 148
3.5 Tribological Studies of Lubricating Oil 148
3.5.1 Density 151
3.5.2 Ash Content 151
3.5.3 Viscosity 151
3.5.4 Flash point 151
3.5.5 Moisture content 152
3.5.6 Pentane and Benzene Insolubles 152
3.5.7 Infrared Spectroscopy 154
3.5.8 Analytical Ferrography 158
3.5.9 Atomic Absorption Spectroscopy 161
3.6 Storage Stability Test of Biodiesel 164
3.6.1 Materials and Methods 165
Chapter: 4 RESULTS AND DISCUSSION 168-
4.1 Introduction 168
4.2 Biodiesel Development and Characterization 168 4.2.1 Production of Mahua Biodiesel 168 4.2.2 Acid Catalyzed Esterification Process 171 4.2.2.1 Effect of Methanol Amount and 172
Reaction Time on Acid Value
4.2.3 Experimental Setup 174
283
4.2.4 Transesterification 175 4.2.4.1 Production of Biodiesel by 176
Changing the Amount of Methanol Used in the Reaction
4.2.4.2 Production of Biodiesel by Changing 178 The Quantity of Catalyst Used in the Reaction
4.2.4.3 Production of Biodiesel by Changing 180 the Reaction Time
4.2.4.4 Production of Biodiesel by Changing 182 The Reaction Temperature
4.2.5 Production of Karanja Biodiesel 183 4.2.6 Acid catalyzed esterification reaction 186 4.2.6.1 Effect of molar ratio and reaction time 186
on acid value
4.2.7 Transesterification 188
4.2.7.1 Production of Biodiesel by Changing 188 the Amount of Methanol
Used in the Reaction
4.2.7.2 Production of Biodiesel by Changing 190 The Quantity of Catalyst Used in the Reaction
4.2.7.3 Production of Biodiesel by Changing 190 the Reaction Time
4.2.7.4 Production of Biodiesel by Changing 192 The Reaction Temperature
4.3 Physico- Chemical Studies 192
4.3.1 Density 195
4.3.2 Viscosity 195
4.3.3 Flash Point 196
xi
4.3.4 Pour point 196
4.3.5 Cloud point 197
4.3.6 Cetane number 198
4.3.7 Copper strip corrosion 198
4.3.8 Distillation property 199
4.3.9 Acid value 200
4.3.10 Ash content 200
4.3.11 Carbon residue 201
4.3.12 Moisture content 202
4.3.13 Sulfur content 202
4.3.14 Phosphorus content 203
4.3.15 Iodine value 203
4.3.16 Saponification value 203
4.3.17 Free Glycerin 204
4.3.18 Total Glycerin 204
4.4 Selection of Different Fuel Matrixes for Engine 204 Testing
4.5 Engine Performance Tests 205
4.5.1 Karanja oil methyl ester (KOME) 206 4.5.1.1 Brake Specific Energy Consumption 206 4.5.1.2 Brake thermal efficiency 207 4.5.1.3 Exhaust Gas Temperature 207 4.5.1.4 Brake specific fuel consumption 208 4.5.2 Mahua oil methyl ester (MOME) 209 4.5.2.1 Brake Specific Energy Consumption 209 4.5.2.2 Brake thermal efficiency 209 4.5.2.3 Exhaust Gas Temperature 211 4.5.2.4 Brake specific fuel consumption 211
4.6 Exhaust Emission Characteristics 211
4.6.1 Karanja oil methyl ester 212
4.6.1.1 NOx emissions 212
xii
4.6.1.2 Unburnt Hydrocarbon Emission 4.6.1.3 Carbon Monoxide Emission 4.6.1.4 Smoke Opacity
213 214 215
4.6.2 Mahua oil methyl ester 216
4.6.2.1 NOx emissions 216
4.6.2.2 Unburnt Hydrocarbon Emission 217 4.6.2.3 Carbon Monoxide Emission 217
4.6.2.4 Smoke Opacity 219
4.7 Effect of Injection Pressures on Engine Performance 219 Characteristics
4.7.1 Karanja oil methyl ester 220
4.7.2 Mahua oil methyl ester 226
4.8 Storage Stability of Biodiesel 231
4.8.1 Karanja oil methyl ester 232
4.8.1.1 Peroxide Value 232
4.8.1.2 Viscosity 232
4.8.1.3 Effect of antioxidants on PV 234
4.8.2 Mahua oil methyl ester 236
4.8.2.1 Peroxide Value 236
4.8.2.2 Viscosity 237
4.8.2.3 Effect of antioxidants on PV 238
4.9 Tribological Studies of Lube Oils 240
4.9.1 Density 240
4.9.2 Ash Content 241
4.9.3 Kinematic viscosity 242
4.9.4 Flash point 244
4.9.5 Moisture content 244
4.9.6 Pentane Insoluble 245
4.9.7 Benzene Insoluble 246
4.9.8 Wear Debris Monitorin 246
4.9.8.1 Ferrography 247
4.9.8.2 Atomic Absorption Spectroscopy 252 4.9.8.3 Infrared Spectroscopy 257
4.10 Long -Term Endurance Test 263
4.11 Wear Measurement of Vital Parts 270
4.12 Combustion Characteristics of diesel- Biodiesel 281 Fuel Blends
Chapter: 5 CONCLUSIONS AND SCOPE FOR FUTURE 284- 288 WORK
5.1 Conclusions 284
5.2 Scope for Future Work 288
REFERENCES APPENDICES
289- 308
Appendix I: Engine Specification
Appendix II: Specifications of Pressure Transducer
Appendix III: Specification OF Charge Amplifier
Appendix IV: Technical Specification of AVL 437 Smoke Meter
Appendix V: Technical Specification of AVL Di- Gas Analyzer Appendix VI: Sampling Instruction
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