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Guest Editorial

SPECIAL ISSUE ON HOMOGENEOUS CHARGED COMPRESSION IGNITION ENGINE

New and exciting engine combustion concepts do not come around often. T

homogeneous charge compression ignition (HCCI) engine is one that has grown in

an important emerging technology. Instead of taking place in flame fronts, as in p

mixed flames in spark-ignition engines or in diffusion flames in diesel engines, co

bustion in an HCCI engine takes place in a distributed manner, often with high diluti

As such, the technology has demonstrated low emissions of NOx

and particulate mat

(PM), and high fuel economy. There are, however, significant technical hurdles that ne

to be overcome before the engine is viable for production. Thus intense research a

engineering efforts on the HCCI engine have been mounted in recent years, as evidenc

by the exponentially growing number of publications on the topic. It is, therefore, fitti

for the International Journal of Engine Research to archive the important developme

in this technology. In this special issue papers have been solicited from experts in t

field on various aspects of the HCCI engine. Many of the papers are an outgrowth

presentations to a well attended SAE TopTec meeting held in Berkeley, California, U

in August 2004. Motivated by the strong interest, solicitations to theInternational Jour

of Engine Research Special Issue were initiated in the Fall of 2004.

Since the mixture in an HCCI engine is auto-ignited through fuelair react

chemistry, the engine demands a higher level of control. The operating conditions

the engine in terms of charge temperature and composition have to sustain ignition anot cause severe knocking and noise/vibration/harshness (NVH). The heat rele

schedule has to be phased appropriately. Thus controlling the HCCI engine is critic

both in optimizing the engine at specific load and speed points, and in extending t

domain of operation. In the first of the two International Journal of Engine Resea

special issues on HCCI engines, eight papers on controlling the HCCI operation

published. The first two papers, from Ford Motor Co., and from collaboration betwe

the University of Michigan and GM, are on controlling the HCCI engines via the therm

environment using regenerative heating and using heat transfer respectively. Then

paper from Brunel University reports on using fuel stratification as means of contr

The papers from University of Tokyo and from Hokkaido University report on the u

of fuel additives for control. Last but not least in this issue, the paper from LoEngineering and two from Stanford University describe the use of fully flexible elect

hydraulic valves to control HCCI dynamically via residual gas trapping.

In the second of the International Journal of Engine Research special issues on HC

engines, nine papers are published covering the areas of fuel, diagnostics, and modelli

Fuel is an important variable for HCCI engines. For example, gasoline is resistant

auto-ignition but its volatility enables easy mixture preparation. Diesel fuel is the oth

way around. Papers respectively from Tokai University, Hokkaido University, and Ky

University report on HCCI engines operating on DiMethyl Ether, low distillation tempe

ture fuels, and natural gas. Since practical diagnostics will play an important role

controlling the engine, two papers from Okayama University and from University

California, Berkeley, report on the low-cost robust detection of ion currents associawith HCCI combustion. Because of the complexity of the phenomena involved, detai

modelling of the physical and chemical processes are needed for understanding

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ii Guest Editorial

dynamics (CFD) modelling; the paper from a collaboration between University

Michigan and Lawrence Livermore Laboratory provides a practical way of implement

a detailed kinetics model into a CFD model. Finally, since HCCI combustion is control

by many parameters, engine calibration is a formidable task. The paper from Univer

of Wisconsin describes a computer simulation-based method for optimizing the eng

performance.

Collectively, the group of papers in these two International Journal of Engine Resea

special issues demonstrates significant progress in HCCI engine technology. It has be

more than 30 years since the technology was reported in the literature, although inten

development only started in the last ten years or so. It will be interesting to see whe

these two International Journal of Engine Research issues stand in the timeline to wh

HCCI becomes a major automotive engine combustion technology.

Wai K Cheng, Bob Dibble, and Dennis Assa

Guest Edit

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