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

i

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

ii

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 In-

charge and staff for use Central Facilities, IIT Delhi for my research work.

iii

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

iv

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

v

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/kW-

hr 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.

vi

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 in-

cylinder 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 in-

line 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.

vii

CONTENTS

Page No.

Certificate i

Acknowledgement ii

Abstract v

Contents vii

List of Figures xv

Last of Tables xxvii

Nomenclature 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

and more probability of wall impingement in a biodiesel

13

viii

fuelled diesel engines

Closure 14

Chapter 2 LITERATURE SURVEY AND OBJECTIVES 16-49

2.1 Effect of biodiesel-diesel blends on injection and spray

characteristics of a diesel engine

17

2.2 Available models/correlations for analysis of spray

characteristics of a diesel engine for base diesel

20

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

(SMD)

24

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

using biodiesel-diesel blends

39

2.6 NOx emission reduction technology for diesel engines 43

2.7 Further improvement of performance and emission

characteristics of diesel engines using hydrogen as an

44

ix

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,

B50 and B100

62

3.2.5 Study of the effect of fuel spray penetration on wall

impingement on the piston bowl of the engine

63

3.2.6 Combustion characteristics of the diesel engine 64

3.2.7 Selection of optimum biodiesel-diesel blend for further

studies on the engine with hardware modification

65

3.2.8 Description of injection parameters for reduction in NOx and

wall impingement of biodiesel (B20) fuelled diesel engine

65

3.2.9 Further reduction in fuel consumption, smoke, CO2 and

NOx of biodiesel fuelled diesel engine using hydrogen as an

67

x

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

different biodiesel-diesel blends and base diesel

75

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

with respect to crank angle

93

4.1.1.7 Analysis of vaporization 98

4.1.2 Analysis of injection and spray characteristics with retarded

injection timing for B20 fuel

103

4.1.3 Analysis of injection and spray characteristics with different

diameters of pump plunger for B20 fuel

107

xi

4.1.4 Analysis of injection and spray characteristics with modified

nozzle configuration for B20 fuel

111

4.1.5 Analysis of injection and spray characteristics with different

nozzle opening pressures (NOP) for B20 fuel

117

4.1.6 Analysis of injection and spray characteristics with advanced

injection timing at NOP: 300 bar for B20 fuel

120

4.2 Combustion characteristics of the diesel engine 123

4.2.1 Analysis of combustion characteristics for B5, B10, B15,

B20, B25, B50, B100 and base diesel

123

4.2.2 Development of Physical and Chemical ignition delay

correlation

131

4.2.2.1 Development of Physical ignition delay (PID)

correlation

133

4.2.2.2 Development of Chemical ignition delay (CID)

correlation

134

4.2.2.3 Development of Total ignition delay (TID)

correlation

134

4.2.2.4 Validation of the developed ignition delay

correlation with measured experimental data

135

4.2.3 Analysis of combustion characteristics with retarded

injection timing for B20 fuel

139

4.2.4 Analysis of combustion characteristics of the engine with 142

xii

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

configuration (6 × 0.188mm) for B20 fuel

146

4.2.6 Analysis of combustion characteristics with different nozzle

opening pressures (NOP) for B20 fuel

149

4.2.7 Analysis of combustion characteristics with advanced

injection timing at NOP: 300 bar for B20 fuel

152

4.3 Performance and emission characteristics of the diesel

engine

155

4.3.1 Analysis of performance and emission characteristics for B5,

B10, B15, B20, B25, B50, B100 and base diesel fuel

155

4.3.2 Analysis of performance and emission characteristics of the

diesel engine with retarded injection timing for B20 fuel

167

4.3.3 Analysis of performance and emission characteristics of the

engine with different diameter of pump plunger for B20 fuel

170

4.3.4 Analysis of performance and emission characteristics with

modified nozzle configuration (6 holes) for B20 fuel

173

4.3.5 Analysis of performance and emission characteristics with

different nozzle opening pressures (NOP) for B20 fuel

175

4.3.6 Analysis of performance and emission characteristics with

advanced injection timing for 6 holes nozzle at 300 bar NOP

179

xiii

for B20 fuel

4.3.7 Further improvement of performance and emission

characteristics of the engine using hydrogen as an additive

182

4.4 Selection of suitable technology for BSEC and NOx

reduction of a biodiesel fuelled diesel engine

190

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

characteristics for biodiesel-diesel blends (B5, B10,

B15, B20, B25, B50 and B100) with base diesel

197

5.1.1.2 Comparison of injection and fuel spray

characteristics of a diesel engine with 5 holes (base)

and 6 holes (modified) nozzle

199

5.1.2 Combustion characteristics of the diesel engine 200

5.1.2.1 Comparison of combustion characteristics for

biodiesel-diesel blends (B5, B10, B15, B20, B25,

B50 and B100) with base diesel

200

5.1.2.2 Comparison of combustion characteristics of a

diesel engine with 5 holes (base) and 6 holes

200

xiv

(modified) nozzle configuration

5.1.3 Performance and emission characteristics of a diesel engine 200

5.1.3.1 Comparison of performance and emission

characteristics for biodiesel-diesel blends (B5, B10,

B15, B20, B25, B50 and B100) with base diesel

201

5.1.3.2 Comparison of performance and emission

characteristics of a diesel engine with 5 holes (base)

and 6 holes (modified) nozzle for B20

201

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