(Hua_zhao) Homogeneous Charge Compression Ignition

i

HCCI and CAI engines for the
automotive industry


ii

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The science and technology of materials in automotive engines
(ISBN 978-1-85573-742-6)
This authoritative book provides an introductory text on the science and technology of
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The materials used in automotive engines are required to fulfil a multitude of functions,
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iii

HCCI and CAI
engines for the
automotive industry
Edited by
Hua Zhao

CRC Press
Boca Raton Boston New York Washington, DC

WOODHEAD

PUBLISHING LIMITED
Cambridge England


iv
Published by Woodhead Publishing Limited, Abington Hall, Abington,
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v

Contents

Contributor contact details

xiii

Preface

xvii

Part I Overview
1

Motivation, Definition, and History of HCCI/CAI
engines

3

H ZHAO, Brunel University West London, UK

1.1
1.2
1.3
1.4
1.5
1.6
1.7

Introduction
Current automotive engines and technologies
Historical background of HCCI/CAI type combustion
engines

Principle of HCCI/CAI combustion engines
Definition of HCCI and CAI combustion engines
Summary
References

3
5
6
10
15
16
16

Part II Gasoline HCCI/CAI combustion engines
2

Overview of CAI/HCCI gasoline engines

21

H ZHAO, Brunel University West London, UK

2.1
2.2
2.3
2.4
2.5
2.6

Introduction

Fundamentals of CAI/HCCI gasoline engines
Effects of use of exhaust gases as diluents
Approaches to CAI/HCCI operation in gasoline engines
Summary
References

21
21
29
35
40
40

3

Two-stroke CAI engines

43

P DURET, IFP, France

3.1

Introduction

43


vi

Contents

3.2
3.3
3.4

Principles of the two-stroke CAI combustion
How to control the two-stroke CAI combustion
The potential application of the two-stroke CAI
combustion
Future trends
Sources of further information and advice
References

67
72
74
75

Four-stroke gasoline HCCI engines with thermal
management

77

3.5
3.6
3.7
4

46

56

J YANG, USA

4.1
4.2
4.3
4.4
4.5
4.6

Introduction
The optimized kinetic process (OKP) HCCI engine
Strengths and weaknesses
Future trends
Sources of further information and advice
References

77
79
91
97
99
101

5

Four-stroke CAI engines with residual gas
trapping

103

H ZHAO, Brunel University West London, UK

5.1
5.2
5.3
5.4
5.5
5.6
5.7
6

Introduction
Principle of CAI operation with residual gas trapping
CAI operation in a four-stroke port fuel injection (PFI)
gasoline engine
Effect of direct injection on CAI combustion in the
four-stroke gasoline engine
Effect of spark ignition on CAI combustion in the
four-stroke gasoline engine
Summary
References
Four-stroke CAI engines with internal exhaust gas
recirculation (EGR)

103
103
107
115

129
132
134
136

A FÜRHAPTER, AVL List GmbH, Austria

6.1
6.2
6.3
6.4
6.5
6.6

Introduction
Principle of CAI with internal EGR
Engine concepts and layout
Thermodynamic results and analysis of CAI with
internal EGR
Transient operation with CAI and internal EGR
Future trends

136
137
141
146
155
162

Contents

vii

6.7
6.8

Sources of further information and advice
References

162
163

7

HCCI control

164

P TUNESTÅL and B JOHANSSON, Lund University, Sweden

7.1
7.2
7.3
7.4
7.5
7.6

Introduction
Control means

Combustion timing sensors
Methods
Summary and future trends
References

164
165
171
174
182
182

8

CAI control and CAI/SI switching

185

N MILOVANOVIC, Delphi Diesel Systems Limited, UK and J TURNER,
Lotus Engineering, UK

8.1

8.5
8.6

Introduction about requirements for the control of the
CAI engine
Problems in controlling the CAI engine
Transition between operating modes (CAI-SI-CAI)

The ‘mixed mode’ CAI-SI engine in operation:
presentation and discussion of the experimental results
obtained
Summary
References

9

Fuel effects in CAI gasoline engines

8.2
8.3
8.4

185
185
188

192
202
203
206

G T KALGHATGI, Shell Global Solutions, UK

9.1
9.2
9.3
9.4
9.5

9.6
9.7
9.8
9.9
9.10
9.11
9.12

Introduction
Practical transport fuels
Auto-ignition quality of fuels
The octane index and the K value
The auto-ignition requirement of an HCCI engine and
fuel effects in combustion phasing
Combustion limits
IMEP and indicated efficiency
Other approaches to characterising fuel performance in
HCCI engines
Fuel requirements of HCCI engines
Summary
References
List of notations
Appendix – HCCI predictor

206
207
210
217
222
224

226
228
230
233
234
236
237


viii

Contents

Part III Diesel HCCI combustion engines
10

Overview of HCCI diesel engines

241

J V PaSTOR, J M LUJÁN, S MOLINA and J M GARCÍA, CMT-Motores
Térmicos, Spain

10.1
10.2
10.3
10.4
10.5
10.6

Introduction
Conventional diesel combustion
Fundamentals of HCCI combustion
Overview of diesel HCCI engines
Summary
References

241
242
247
252
261
263

11

HCCI combustion with early and multiple injections
in the heavy-duty diesel engine

267

Y AOYAGI, New ACE, Japan

11.1
11.2
11.3
11.4
11.5
11.6
11.7

11.8
11.9
12

Introduction
Experimental apparatus
Early injection HCCI (PREDIC) by low cetane fuel
Multiple injections HCCI by low cetane fuel (two-stage
combustion, MULDIC)
HCCI for normal cetane fuel
Summary
Acknowledgements
References
Nomenclature
Narrow angle direct injection (NADI™) concept for
HCCI diesel combustion

267
268
271
274
277
285
286
286
288
289

B GATELLIER, IFP, France

12.1
12.2
12.3
12.4
12.5
12.6
12.7

Introduction
The NADI™ concept overview
First results and limitations
Development of the concept
Evaluation of the concept in a multi-cylinder engine
Future trends
References

289
290
292
296
307
318
320

13

Low-temperature and premixed combustion concept
with late injection

322

S KIMURA, Nissan Motor Company, Japan

13.1
13.2

Introduction
Basic concept of low-temperature and premixed combustion

322
323


Contents

13.3
13.4
13.5
13.6
13.7
14

Characteristics of combustion and exhaust emissions with
modulated kinetics (MK) combustion
Second generation of MK combustion
Emission performance improvement of second generation
of MK combustion
Future trends
References
HCCI fuel requirements

ix

324
330
334
337
340
342

T W RYAN III, SWRI, USA

14.1
14.2
14.3
14.4
14.5
14.6
14.7
14.8
14.9

Introduction
Background
Diesel fuel HCCI
HCCI fuel ignition quality
Gasoline HCCI
HCCI fuel specification
Fundamental fuel factors
Future trends

References

342
342
345
350
354
358
360
361
362

Part IV HCCI/CAI combustion engines with alternative fuels
15

Natural gas HCCI engines

365

N IIDA, Keio University, Japan

15.1
15.2
15.3
15.4
15.5
15.6
15.7
15.8
15.9

15.10
15.11
15.12
15.13
15.14

CNG HCCI engine experiment and calculation conditions
CNG composition
Influence of equivalence ratio
Auto-ignition timing and combustion duration
Auto-ignition temperature and auto-ignition pressure
Exhaust emission, maximum cycle temperature and
combustion efficiency
Influence of n-butane on auto-ignition and combustion in
methane/n-butane/air mixtures
Summary of naturally aspirated natural gas HCCI engine
Supercharged natural gas HCCI engine setup and
experiments
Performance and exhaust gas characteristics at a
compression ratio of 17
Performance and emission characteristics at a
compression ratio of 21
Potential of natural gas turbocharged HCCI engines
Summary
References

365
366
369
371

372
374
376
383
383
385
388
389
391
392


x

16

Contents

HCCI engines with other fuels

393

N IIDA, Keio University, Japan

16.1
16.2
16.3
16.4
16.5
16.6

16.7
16.8
16.9

Characterization of DME
DME HCCI engine
DME chemical reaction model
Combustion completeness in the DME HCCI engine
Combustion control system for a small DME HCCI
engine
Method of combining DME and other fuels
Reducing pressure rise rate by introducing ‘unmixed-ness’
of DME/air mixture
Summary
References

393
394
394
396
408
421
423
425
429

Part V Advanced modeling and experimental techniques
17

Auto-ignition and chemical kinetic mechanisms of

HCCI combustion

433

C K WESTBROOK and W J PITZ, Lawrence Livermore National
Laboratory, USA and H J CURRAN, National University of
Ireland, Galway

17.1
17.2
17.3
17.4
17.5
17.6
17.7
17.8
18

Introduction
Kinetics of auto-ignition
Reaction types
Temperature regimes of auto-ignition
Illustrations of auto-ignition in the rapid compression
machine
Kinetic models for HCCI ignition
Summary
References
Overview of modeling techniques and their
applications to HCCI/CAI engines

433
434
435
437
445
451
453
453
456

S M ACEVES, D L FLOWERS, R W DIBBLE and A BABAJIMOPOULOS,
Lawrence Livermore National Laboratory, USA

18.1
18.2
18.3
18.4
18.5
18.6
18.7
18.8

Introduction
Fundamentals of HCCI ignition and combustion
The chemistry of HCCI
Prediction of ignition in HCCI engines
Detailed calculation of HCCI combustion and emissions
Prediction of operating range
Summary and future trends
References

456
457
458
462
465
468
470
471


Contents

19

Overview of advanced optical techniques and their
applications to HCCI/CAI engines

xi

475

M RICHTER, Lund University, Sweden

19.1
19.2
19.3
19.4
19.5
19.6

19.7
19.8

Introduction
Diagnostic approaches
Spectroscopic environment
Chemiluminescence imaging
Laser induced fluorescence
Thermographic phosphors
Future trends
References

475
476
481
482
484
498
500
502

Part VI Future directions for CAI/HCCI engines
20

Outlook and future directions in HCCI/CAI engines

507

H ZHAO, Brunel University West London, UK

Index

510


xii


xiii

Contributor contact details

(* = main contact)

Editor

Chapter 4

Professor H. Zhao
School of Engineering and Design
Brunel University West London
Uxbridge
Middlesex, UB8 3PH
UK

J. Yang
582 Terrace Court
Canton, MI 48188
USA

E-mail:

Chapter 6

Chapters 1, 2, 5 and 20
H. Zhao
School of Engineering and Design
Brunel University West London
Uxbridge
Middlesex, UB8 3PH
UK
E-mail:

Chapter 3
P. Duret
IFP
228-232 avenue Napoléon
Bonaparte
92852 Rueil-Malmaison Cedex
France

E-mail:

A. Fürhapter
AVL List GmbH
Hans-List-Platz 1
A-8020 Graz
Austria
E-mail:

Chapter 7
Per Tunestål
Lund University
Faculty of Engineering
Dept. of Energy Sciences/
Combustion Engines
PO Box 118
221 00 Lund
Sweden
E-mail:

E-mail:


xiv

Contributor contact details

Chapter 8

Chapter 11

N. Milovanovic*
Combustion, NVH and Fuel
Department Manager
Delphi Diesel Systems
Courteney Road
Hoath Way
Gillingham ME8 ORU

Y. Aoyagi
Representative and Managing
Director
Research Department
New ACE. Institute Co., Ltd.
2530 Karima, Tsukuba-shi,
Ibaraki Pref.,
305-0822
Japan

J. Turner
Chief Engineer
Powertrain Advanced Concept
Lotus Engineering
Hethel
Norwich, NR14 8EZ
UK
E-mail:



Chapter 9
G. T. Kalghatgi
Shell Global Solutions, UK
Cheshire Innovation Park
PO Box 1
Chester, CH1 3SH
UK
E-mail:

Chapter 10
J. V. Pastor*, J. M. Luján,
S. Molina and J. M. García
CMT-Motores Térmicos
Universidad Politécnica de Valencia
Camino de Vera, s/n
46022 Valencia
Spain
E-mail:




E-mail:

Chapter 12
Bertrand Gatellier
IFP
1 et 4, avenue de Bois-Préau
92852 Rueil-Malmaison Cedex
France
E-mail: bertrand.gatellierfp.fr

Chapter 13
Shuji Kimura
Nissan Motor Co., Ltd.,
1 Natsushima-cho, Yokosuka-shi
Kanagawa 237-8523
Japan
E-mail:

Contributor contact details

Chapter 14
Thomas W. Ryan III
Institute Engineer
Southwest Research Institute
P.O. Drawer 28510
San Antonio
Texas 78228-0510
USA
E-mail:

Chapters 15 and 16
N. Iida
System Design Engineering Dept
Keio University
3-14-1 Hiyoshi
Kohoku-ku
Yokohama 223-8522
Japan
E-mail:

Chapter 17
C. K. Westbrook* and W. J. Pitz
Lawrence Livermore National
Laboratory
7000 East Avenue
L-644

Livermore, CA 94551
USA
E-mail:

xv

H. J. Curran
Chemistry Department
NUI Galway
University Rd
Galway
Ireland
E-mail:

Chapter 18
S. Aceves
Lawrence Livermore National
Laboratory
7000 East Avenue
L-644
Livermore, CA 94551
USA
E-mail:

Chapter 19
M. Richter
Dept. of Physics
Div. of Combustion Physics
PO Box 118
S-22100 Lund

Sweden
E-mail:


xvi


xvii

Preface

Controlled Auto-Ignition (CAI) and Homogeneous Charge Compression
Ignition (HCCI) combustion are radically different from the conventional
spark ignition (SI) combustion in a gasoline engine and compression ignition
(CI) diffusion combustion in a diesel engine. The combination of a diluted
and premixed fuel and air mixture with multiple ignition sites throughout the
combustion chamber eliminates the high combustion temperature zones and
prevents the production of soot particles, hence producing ultra-low NOx
and particulate emissions. The use of lean, or more often diluted, air/fuel
mixture with recycled burned gases permits unthrottled operation of a CAI/
HCCI gasoline engine, thus yielding higher engine efficiency and better fuel
economy than SI combustion. Therefore, CAI/HCCI combustion represents
for the first time a combustion technology that can simultaneously reduce
both NOx and particulate emissions from a diesel engine and has the capability
of achieving simultaneous reduction in fuel consumption and NOx emissions
from a gasoline engine.
Based on these promises, the interest in CAI/HCCI combustion exploded
at the turn of the new millennium and has since grown so much that the
HCCI session has consistently been the largest session in the world’s largest
annual gathering of automotive engineers, the annual SAE Congress in Detroit,

for the last five years. Each year, scores of papers are published at a number
of international conferences and in various journals. It would be a daunting
task to read every publication in this field. In addition, it presents a particular
challenge for someone to plan working in this field or for someone to make
a management decision on CAI/HCCI technology. In the meantime, the
research and development efforts in this field over the last ten years have
reached a stage that not only has better understanding of the underlying
physical and chemical process in CAI/HCCI combustion been achieved but
also several dominant and promising means have emerged for the adoption
of CAI/HCCI combustion in automotive applications. It is therefore timely
that the large volume of technical information should be made available in
an organised way so that the description of the fundamental processes, insights


xviii

Preface

on technical issues, and identification of future research and development
can be found between one set of covers.
Following the introduction and history of CAI/HCCI engines in Part I, the
main body of the book is organised in six parts: Part II on the CAI/HCCI
gasoline engines, Part III on diesel fuelled HCCI engines, Part IV on HCCI
engines with alternative fuels, Part V on latest developments in kinetics, and
analytical and experimental techniques for CAI/HCCI combustion research.
Part VI concludes the book with a brief discussion of future directions of
CAI/HCCI engines.
In Part II, a detailed description of CAI/HCCI combustion in the gasoline
engine is provided in Chapter 2. Chapter 3 presents an interesting account of
the discovery of this alternative and originally unwanted combustion mode

in two-stroke gasoline engines in the 1970s and its subsequent turnabout on
improving two-stroke engines’ performance and emissions. Chapter 3 also
serves as an introduction to the residual gas trapping method that was
subsequently adopted to achieve CAI combustion in the four-stroke gasoline
engine. Chapters 4 to 6 present and discuss three most promising approaches
to achieve CAI/HCCI combustion in the four-stroke gasoline engine. As
CAI/HCCI combustion does not have a direct means of controlling its
combustion process, closed loop control is necessary to achieve optimised
CAI/HCCI engine operation. Chapter 7 introduces the sensors and control
techniques and their applications for closed loop control of the CAI/HCCI
engine. Chapter 8 presents approaches to achieve switching between the
alternative combustion mode and the conventional SI mode, which would be
necessary to cover the whole operational range of a gasoline engine. Part II
concludes in Chapter 9 with a discussion on the fuel properties that are
relevant to the CAI/HCCI gasoline engine.
Part III starts with an overview on the HCCI combustion in direct injection
diesel engines in Chapter 10. A main challenge in achieving diesel HCCI
combustion is to obtain a sufficiently premixed air and fuel mixture before
the start of ignition. Due to the high pressure injection employed for fast
atomisation, wall wetting will occur with the very early fuel injection that is
desirable for premixed charge operation. Therefore, alternative solutions
have to be found. Chapter 11 provides a description of the progress made in
the research on premixed type HCCI combustion in heavy duty diesel engines
at New ACE institute over the last decade. The wall wetting was initially
avoided by the use of two side-mounted injectors, but later work focused on
the use of optimisation of fuel injection strategy and high exhaust gas
recirculation (EGR). Whilst at IFP, the wall wetting problem has been resolved
by the adoption of a narrow cone angle fuel injector, as discussed in Chapter
12, together with information on the radically different piston bowl design
and different injection strategies suited for high and low load operations.

Chapter 13 presents Nissan’s HCCI diesel combustion concept, MK, a HCCI


Preface

xix

combustion technology that has been employed in production engines for
several years. Late injection is employed to avoid the wall wetting. Together
with high EGR and high swirl, HCCI type diesel combustion has been achieved
at part-load operations in light-duty diesel engines. Part III ends in
Chapter 14 with an overview on fuel properties and their influence on HCCI
combustion.
Part IV focuses on HCCI engines with gaseous fuels. Due to its abundant
supply, natural gas is considered as a viable alternative fuel for automotive
applications. Its ignition and combustion characteristics in HCCI combustion
are discussed in Chapter 15. The other gaseous fuel considered is dimethyl
ether (DME), which can be produced from biomass as well as from coal or
natural gas. Chapter 16 presents the results of an analytical study of DME
HCCI combustion and then gives a detailed description of a prototype DME
HCCI engine.
Part V is concerned with the fundamentals of CAI/HCCI combustion. In
Chapter 17, the kinetic aspects of CAI/HCCI combustion are reviewed. Detailed
discussion is given regarding hydrocarbon oxidation chemistry and autoignition
processes leading to HCCI combustion. This is followed by an overview on
various HCCI engine modelling approaches with differing computational
complexity in Chapter 18. Finally, the advanced laser diagnostic techniques
for in-cylinder air/fuel distribution, autoignition, and combustion in CAI/
HCCI engines are presented in Chapter 19 with some excellent images taken
from HCCI combustion engines. The final part of the book explores the

current trends in the future development of CAI/HCCI engines.
This book has been written by the leading researchers in this field, who
have contributed with the intention of providing a systematic description and
personal insights on detailed technical issues in their field of expertise. It
would serve as an excellent base for anyone who is interested in the field.
The references listed at the end of each chapter will also provide a convenient
way for someone who needs to have ready access to the most relevant
literature.
I am delighted to have taken on such an enjoyable task, during which I
have had the pleasure of corresponding with the contributing authors, whom
I thank for agreeing to undertake the work and for sticking to the agreed
publication schedule. I would also like to thank Sheril Leich and Ian Borthwick
of Woodhead Publishing for initiating the project and their professional
support in preparing this book.
Hua Zhao
Brunel University, West London
2007


xx


Part I
Overview

1


2

HCCI and CAI engines for the automotive industry


1
Motivation, definition and history of
HCCI/CAI engines
H Z H A O, Brunel University West London, UK

1.1

Introduction

Since their introduction around a century ago, IC engines have played a key
role, both socially and economically, in shaping of the modern world. Their
suitability as an automotive power plant, coupled with a lack of practical
alternatives, means road transport in its present form could not exist without
them. However, in recent decades, serious concerns have been raised with
regard to the environmental impact of the gaseous and particulate emissions
arising from operation of these engines. As a result, ever tightening legislation,
that restricts the levels of pollutants that may be emitted from vehicles, has
been introduced by governments around the world. In addition, concerns
about the world’s finite oil reserves and, more recently, by CO2 emissions
brought about climate change has lead, particularly in Europe, to heavy
taxation of road transport, mainly via on duty on fuel. These two factors
have lead to massive pressure on vehicle manufacturers to research, develop
and produce ever cleaner and more fuel-efficient vehicles. Though there are
technologies that could theoretically provide more environmentally sound
alternatives to the IC engine, such as fuel cells, practicality, cost, efficiency
and power density issues will prevent them displacing IC in the near future.
Over the last 30 years, levels of NOx, CO and VOC emissions from

vehicles have been dramatically reduced and this has largely been achieved
by the use of exhaust gas after-treatment systems, such as the catalytic
converter. This has been motivated by a continually tightening band of
legislation related to emission of these pollutants that has been enforced in
the United States (USA), Japan and Europe (EU). Table 1.1 shows the permitted
emission levels for the EU and California Air Resources Board.
EU emissions legislation demands that all vehicles comply with the particular
standard that is in force at that time they are manufactured. The permitted
emission levels are given on a specific basis and are the maximum permitted
over a standard drive cycle, intended to be representative of a typical vehicle
journey. Legislation from CARB is included in Table 1.1 because it is currently
3


4

HCCI and CAI engines for the automotive industry

Table 1.1 Current and future EU and CARB legislated emission levels for passenger
cars [1, 2]
Euro
Standard

Year

Engine
type

CO
(g/km)

HC/NMOG
(g/km)

NOx
(g/km)

HC+NOx
(g/km)

PM
(g/km)

Euro III

2001

SI
CI

2.3
0.64

0.2
–

0.15
0.5

–

0.56

–
0.05

Euro IV

2005

SI
CI

1.00
0.5

0.1
–

0.08
0.25

–
0.3

–
0.025

Euro V

2008

SI
CI

–
–

0.05
0.05

0.08
0.08

–
–

0.0025
0.0025

2

0.033

0.04

–

–

–

4.2
2.1
1

–
0.056
0.034
0.006

–
0.07
0.07
0.02

–
–
–
–

–
0.01
0.01
–

CARB
(LEV II)
TLEV
LEV
ULEV
SULEV

2004–10

(CARB) for passenger cars [1, 2].

the most stringent in the world. The US legislation is significantly different
from the EU standards in that it operates a ‘fleet-averaged’ system, where
the average emissions output from the total sales of a manufacturer’s product
range must be within the prescribed limits. In this way, a manufacturer can,
for example, use sales of SULEVS to offset the higher emissions from TLEVS
to keep within the required limits. In addition, differences in the test drive
cycle and the measurement method of VOC’s make direct comparison of the
‘Euro’ and CARB standards impossible. Johnson [3] has shown, through
normalisation of the US and European standards, that the levels of uHC
permitted by the US LEV II and EURO IV standards are roughly similar.
However, he also concluded that the US standard permits approximately half
the amount of NOx emissions, which was likely to seriously limit the
penetration of HSDI Diesel and GDI engines into this market until adequate
exhaust gas after-treatment systems are developed.
In addition to standards concerned with limiting local pollution, government
policy is used to reduce global climate change by attempting to limit vehicle
CO2 emissions. In the UK and much of Europe this takes the form of heavy
taxation of fuel, discounts on Road Fund Duty for small capacity vehicles
and, most recently, the introduction of a sliding scale of ‘company car tax’
that heavily penalises the operation of vehicles with high CO2 emissions. As
part of this, CO2 emission levels for all new passenger cars and LGVs must
be published. Driven by this strong desire to reduce CO2 emissions, a voluntary
agreement has been reached between many of the major European car
manufacturers to reduce their fleet average fuel consumption from the current
160g/km to 120g/km by the year 2012, equivalent to a 25% reduction. In the