EFFECTS OF INJECTION PARAMETERS ON FUEL SPRAY AND COMBUSTION CHARACTERISTICS OF A BIODIESEL FUELLED DIESEL ENGINE LAHANE SUBHASH VASUDEO CENTRE FOR ENERGY STUDIES INDIAN INSTITUTE OF TECHNOLOGY DELHI OCTOBER 2012
Indian Institute of Technology Delhi (IITD), New Delhi, 2012
EFFECTS OF INJECTION PARAMETERS ON FUEL SPRAY AND COMBUSTION CHARACTERISTICS OF A BIODIESEL FUELLED DIESEL ENGINE by LAHANE SUBHASH VASUDEO CENTRE FOR ENERGY STUDIES Submitted In fulfillment of the requirements of the degree of Doctor of Philosophy to the INDIAN INSTITUTE OF TECHNOLOGY DELHI OCTOBER 2012
Dedicated to my beloved Parents, Wife, Son and Daughter
CERTIFICATE The thesis entitled Effects of Injection Parameters on Fuel Spray and Combustion Characteristics of a Biodiesel Fuelled Diesel Engine being submitted by Mr. Lahane Subhash Vasudeo to the Indian Institute of Technology Delhi, for the award of the degree of Doctor of Philosophy, is a record of bona fide research work carried out by him. He was worked under my supervision, and has fulfilled the requirements for the submission of this thesis, which has attained the standard required for a Ph. D. degree of the Institute. The results presented in this thesis have not been submitted elsewhere for the award of any degree or diploma. I certify that he has pursued the prescribed course of research. October 2012 Dr. K. A. Subramanian Associate Professor, Centre for Energy Studies Indian Institute of Technology Delhi Hauz Khas, New Delhi 110 016 i
ACKNOWLEDGEMENTS With all due respect, I would like to express my deep sense of gratitude, indebtedness, and thankfulness to my supervisor and guide Dr. K. A. Subramanian for his constant and consistent, inspiring guidance and utmost co-operation at every stage, which culminated in successful completion of my research work. I, without any doubt in my mind, consider myself most fortunate to work under Dr. K. A. Subramanian s guidance. I heartily thank almighty God to give me an opportunity to work under Dr. K. A. Subramanian s able guidance. To him, I am forever, indebted. I am very much thankful to Prof. R. P. Sharma, Head, CES for providing me required research facilities. I would also thank Prof. S. C. Kaushik (Former Head, CES) for providing me facilities during the initial period of my research work. My sincere thank to all my Student Research Committee (SRC) members of Prof. R. P. Sharma (SRC-Chairman), Prof. T. S. Bhatti (Ph. D. Coordinator, CES), Prof. (Retd.) J. P. Subrahmanyam and Prof. (Retd.) M. K. G. Babu for their valuable suggestions on my research work. Their suggestions helped me immensely to improve the quality of my research work. I would like to thank Prof. L. M. Das for his encouragement on my research work. I thank to Prof. M. G. Dastidar for permitting me to use her lab facilities for certain measurement required for my research work. I also would like to thank Faculty Incharge and staff for use Central Facilities, IIT Delhi for my research work. ii
My sincere thank to Department of Science and Technology (DST), Council of Scientific and Industrial Research (CSIR) and Industrial R & D, IIT Delhi for supporting fund for presenting my research work at American Society of Mechanical Engineering (ASME) International Conference at Torino, Piemonte, Italy. I thank Centre for Energy Studies staff member Mrs. N. K. Puri and Mrs. Harjeet Kaur Narula for official work related to my research work. I am grateful to my colleagues and my friends Dr. C. H. Biradar, Dr. Reji Mathai, Dr. Karu Ragupathy, Mr. Venkateswrlu Chintala, Mr. Sunmeet Singh, Mr. Chandu Madankar, Dr. Lalit Joshi, Mr. R. Balasubramanian, Mr. Salvi, Mr. Ramesh Jeeragal and Mr. Ashok for their cooperation. My special thanks go to Mr. Charan R., Mr. Vaibhav V. Jadhav and Mr. Vinaya C. Mathad for their support and conducive cooperation during my experimental work. I also would like to convey my sincere thanks to Mr. Batra and Mr. Attar Sing from of Engines and Unconventional Fuels Laboratory, Mr. Bhaskar and Mr. Ramakrishna from Workshop and Mr. Shankar Lal Sharma from IT Lab, CES for their kind support and help in completing this research work. I have no word to express my sentiments for my parents and in-laws, Shri Vasudeo S. Lahane, Smt Rukhmina V. Lahane and Shri Prabhakar N. Kakde, Smt. Shalini P. Kakde who always loved and encouraged me for higher education. I have no befitting words to express deep sentiments towards my Wife: Smt. Sheetal Subhash Lahane, Son: Mr. Bhargav Subhash Lahane and Daughter: Ms. Nityasree iii
Subhash Lahane for their whole hearted support and patience during the period of my study/research work. I also would like to extend my sentiments towards my Brother: Shri. Narendra Vasudeo Lahane, Sister- in- law: Smt. Anjali Narendra Lahane and Niece: Ms. Shrusti Lahane for their kind support during the period of my study. Last but not least, I would like to express my thanks and deep gratitude to the omnipresent almighty God by whose grace, my dream of completing this thesis has come true. New Delhi Lahane Subhash Vasudeo October 2012 iv
ABASTRACT This research work is aimed at study of effect of injection parameters (in-line fuel injection pressure, injection delay, dynamic injection timing (DIT) and injection duration) on fuel spray, combustion, performance and emission characteristics of a diesel engine (7.4 kw rated power output) for different biodiesel-diesel blends (B5 to B100). CO, HC and smoke emissions decreased with all biodiesel-diesel blends at all loads. However, NOx emission increased with all biodiesel-diesel blends due to higher spray penetration, oxygen content, advancement in dynamic injection timing and increase in in-cylinder temperature. At the rated load, NOx and spray penetration increased from 6.24 g/kw-hr and 34.28 mm with base diesel to 7.39 g/kw-hr and 36.29 mm with B20 and 8.07 g/kwhr and 37.5 mm with B100 respectively. The spray penetration increases with biodiesel due to increase in in-line fuel injection pressure (due to higher bulk modulus) resulting in a probability of wall impingement and high NOx emission. The optimum biodiesel-diesel blend based on no wall impingement and less increase in NOx emission (B15: 4.1 %; B20: 15.6 % and B100: 22.8 %) in an unmodified (conventional) diesel engine is up to B15 whereas B20 is found to be the critical limit of wall impingement (within uncertainty limits of ±1. 3 %). However, the wall impingement and NOx emission is higher with higher biodiesel-diesel blends beyond B20. Further experimental tests were conducted on the diesel engine with a hardware modification (injection timing (retard and advance), injection pump s plunger size, nozzle configuration (number of holes and size) and nozzle opening pressure) for B20 in order to reduce wall impingement and NOx emission at source level. The retarded injection timing in a modified engine decreases the in-line fuel injection pressure resulting in lower spray penetration. No wall impingement was observed with retarded injection timing due to higher distance between the bowl and injector tip than spray penetration. However, the retarded injection timing does not give desirable results except no wall impingement and NOx (4.82 g/kw-hr) as it increases BSEC, CO, HC, and smoke. v
The pump s plunger diameter was varied from 9.5 mm (base) to 9 mm and 8.7 mm. As the volume of fuel pumped by the plunger per unit crank angle would influence the injection pressure at the nozzle, the decrease in plunger diameter decreases the in-line fuel injection pressure. The modification of pump s plunger diameter gives beneficial results in terms of lower NOx (5.01 g/kw-hr) and no probability of wall impingement. However, BSEC, CO, HC and smoke emissions increased with modified pump s plunger. The injector nozzle configuration was changed from 0.19 mm (hole diameter) 5 holes (base) to 0.188 mm (hole diameter) 6 holes (modified). The in-line fuel injection pressure decreased with modified nozzle due to lower fuel quantity per hole results in lower spray penetration and no wall impingement. NOx and smoke emissions decreased with modified nozzle configuration. The reasons for reduction in NOx emission is mainly due to the automatic retardation of DIT, lower spray penetration, and lower localized incylinder temperature. The smoke emission decreased due to the smaller sauter mean diameter (SMD) resulting in better mixing and vaporization. In the final phase, the tests were conducted with hydrogen as an additive (7.7 % and 11.2 % energy share). The inline fuel injection pressure decreased with hydrogen energy share due to reduction in main fuel quantity results in lower spray penetration and no wall impingement. All the emissions decreased up to 11.2 % energy share. However, NOx emission increased with 14 % energy share due to dominant effect of higher in-cylinder pressure and temperature. The salient points emerged from the study are that the diesel engine fueled with B5 to B15 does not have a probability of wall impingement where as it is critical (uncertainty: ±1.3%) with B20 but the probability increases with higher biodiesel-diesel blends (B25, B50 and B100). Techniques such as the injection timing retardation and plunger modification do not give desirable results except no wall impingement and NOx reduction. The modified injector configuration gives the best results in terms of lower NOx and wall impingement probability as compared to the all techniques. Overall, it can be concluded that modification of injector nozzle configuration of a diesel engine for use of biodiesel-diesel blend is necessary for reducing NOx emission at source level along with the additional benefit of BSEC and smoke reduction without problem of wall impingement. vi
CONTENTS Page No. Certificate Acknowledgement Abstract Contents List of Figures Last of Tables Nomenclature i ii v vii xv xxvii xxix Chapter 1 INTRODUCTION 1-15 1.1 Injection and fuel spray characteristics of diesel engines 2 1.1.1 Spray break-up length 5 1.1.2 Spray cone angle 5 1.1.3 Sauter mean diameter (SMD) 5 1.1.4 Spray penetration 6 1.1.5 Wall impingement 6 1.1.6 Air entrainment 7 1.2 Combustion characteristics of diesel engines 7 1.3 Performance and emission characteristics of diesel engines 9 1.4 Control strategies for solving problems higher NOx emission 13 and more probability of wall impingement in a biodiesel vii
fuelled diesel engines Closure 14 Chapter 2 LITERATURE SURVEY AND OBJECTIVES 16-49 2.1 Effect of biodiesel-diesel blends on injection and spray 17 characteristics of a diesel engine 2.2 Available models/correlations for analysis of spray 20 characteristics of a diesel engine for base diesel 2.2.1 Available models for analysis of spray break-up length 20 2.2.2 Available models for analysis of spray cone angle 22 2.2.3 Available models for analysis of sauter mean diameter 24 (SMD) 2.2.4 Available models for analysis of spray penetration 26 2.2.5 Available models for analysis of air entrainment 29 2.2.6 Available models for analysis of vaporization 30 2.3 Wall impingement 32 2.4 Ignition and combustion characteristics of a diesel engine 36 2.5 Performance and emission characteristics of a diesel engine 39 using biodiesel-diesel blends 2.6 NOx emission reduction technology for diesel engines 43 2.7 Further improvement of performance and emission 44 characteristics of diesel engines using hydrogen as an viii
additive 2.8 Research gap 45 Closure 48 2.9 Objectives 49 Chapter 3 METHODOLOGY AND EXPERIMENTAL DETAILS 50-72 3.1 Methodology 51 3.2 Experimental details 54 3.2.1 Biodiesel preparation using Transesterification process 54 3.2.2 Fuel quality analysis of biodiesel and base diesel 55 3.2.3 Development of experimental setup 59 3.2.4 Baseline data generation for diesel, B5, B10, B15, B20, B25, 62 B50 and B100 3.2.5 Study of the effect of fuel spray penetration on wall 63 impingement on the piston bowl of the engine 3.2.6 Combustion characteristics of the diesel engine 64 3.2.7 Selection of optimum biodiesel-diesel blend for further 65 studies on the engine with hardware modification 3.2.8 Description of injection parameters for reduction in NOx and 65 wall impingement of biodiesel (B20) fuelled diesel engine 3.2.9 Further reduction in fuel consumption, smoke, CO2 and 67 NOx of biodiesel fuelled diesel engine using hydrogen as an ix
additive 3.3 Uncertainty analysis 69 3.3.1 Uncertainty analysis of measured parameters 69 3.3.2 Uncertainty analysis of calculated parameters 71 Closure 72 Chapter 4 RESULTS AND DISCUSSION 73-195 4.1 Injection and fuel spray characteristics of the diesel engine 74 4.1.1 Analysis of injection and fuel spray characteristics for 75 different biodiesel-diesel blends and base diesel 4.1.1.1 Analysis of spray break-up length 84 4.1.1.2 Analysis of spray cone angle 86 4.1.1.3 Analysis of sauter mean diameter (SMD) 87 4.1.1.4 Analysis of spray penetration 90 4.1.1.5 Analysis of air entrainment 92 4.1.1.6 Analysis of wall impingement on piston bowl 93 with respect to crank angle 4.1.1.7 Analysis of vaporization 98 4.1.2 Analysis of injection and spray characteristics with retarded 103 injection timing for B20 fuel 4.1.3 Analysis of injection and spray characteristics with different 107 diameters of pump plunger for B20 fuel x
4.1.4 Analysis of injection and spray characteristics with modified 111 nozzle configuration for B20 fuel 4.1.5 Analysis of injection and spray characteristics with different 117 nozzle opening pressures (NOP) for B20 fuel 4.1.6 Analysis of injection and spray characteristics with advanced 120 injection timing at NOP: 300 bar for B20 fuel 4.2 Combustion characteristics of the diesel engine 123 4.2.1 Analysis of combustion characteristics for B5, B10, B15, 123 B20, B25, B50, B100 and base diesel 4.2.2 Development of Physical and Chemical ignition delay 131 correlation 4.2.2.1 Development of Physical ignition delay (PID) 133 correlation 4.2.2.2 Development of Chemical ignition delay (CID) 134 correlation 4.2.2.3 Development of Total ignition delay (TID) 134 correlation 4.2.2.4 Validation of the developed ignition delay 135 correlation with measured experimental data 4.2.3 Analysis of combustion characteristics with retarded 139 injection timing for B20 fuel 4.2.4 Analysis of combustion characteristics of the engine with 142 xi
modified plunger (9.5 mm (base) to 9 mm and 8.7 mm diameter) for B20 fuel 4.2.5 Analysis of combustion characteristics with modified nozzle 146 configuration (6 0.188mm) for B20 fuel 4.2.6 Analysis of combustion characteristics with different nozzle 149 opening pressures (NOP) for B20 fuel 4.2.7 Analysis of combustion characteristics with advanced 152 injection timing at NOP: 300 bar for B20 fuel 4.3 Performance and emission characteristics of the diesel 155 engine 4.3.1 Analysis of performance and emission characteristics for B5, 155 B10, B15, B20, B25, B50, B100 and base diesel fuel 4.3.2 Analysis of performance and emission characteristics of the 167 diesel engine with retarded injection timing for B20 fuel 4.3.3 Analysis of performance and emission characteristics of the 170 engine with different diameter of pump plunger for B20 fuel 4.3.4 Analysis of performance and emission characteristics with 173 modified nozzle configuration (6 holes) for B20 fuel 4.3.5 Analysis of performance and emission characteristics with 175 different nozzle opening pressures (NOP) for B20 fuel 4.3.6 Analysis of performance and emission characteristics with 179 advanced injection timing for 6 holes nozzle at 300 bar NOP xii
for B20 fuel 4.3.7 Further improvement of performance and emission 182 characteristics of the engine using hydrogen as an additive 4.4 Selection of suitable technology for BSEC and NOx 190 reduction of a biodiesel fuelled diesel engine Closure 193 Chapter 5 CONCLUSIONS 196-203 5.1 Conclusions 197 5.1.1 Injection and fuel spray characteristics of the diesel engine 197 5.1.1.1 Comparison of injection and fuel spray 197 characteristics for biodiesel-diesel blends (B5, B10, B15, B20, B25, B50 and B100) with base diesel 5.1.1.2 Comparison of injection and fuel spray 199 characteristics of a diesel engine with 5 holes (base) and 6 holes (modified) nozzle 5.1.2 Combustion characteristics of the diesel engine 200 5.1.2.1 Comparison of combustion characteristics for 200 biodiesel-diesel blends (B5, B10, B15, B20, B25, B50 and B100) with base diesel 5.1.2.2 Comparison of combustion characteristics of a 200 diesel engine with 5 holes (base) and 6 holes xiii
(modified) nozzle configuration 5.1.3 Performance and emission characteristics of a diesel engine 200 5.1.3.1 Comparison of performance and emission 201 characteristics for biodiesel-diesel blends (B5, B10, B15, B20, B25, B50 and B100) with base diesel 5.1.3.2 Comparison of performance and emission 201 characteristics of a diesel engine with 5 holes (base) and 6 holes (modified) nozzle for B20 5.1.4 Fuel modification: Hydrogen as additive 202 5.2 Future scope of the study 202 References 204-217 Appendices 218-225 Appendix 1 219 Appendix 2 220 Appendix 3 221 Appendix 4 223 Appendix 5 224 Publication 226 Bio-data 228 xiv