Preface The diesel engine is one of the most efficient types of heat engines and is widely used as a prime mover for many applications. The most important process that determines the performance of the diesel engine is its combustion process. Since Rudolph Diesel invented the compression ignition engine more than a century ago@ our knowledge of the combustion process has increased tremendously. In recent years@ with the aid of computers@ we have made great progress in the study of engine combustion modeling. As a result@ our knowledge of the intricacies of the inner workings of engine cylinders has improved vastly. However@ because of the complexities of the processes involved in the practical diesel engine@ there are still too many unknowns that prevent computational predictions from having the accuracy level required by industry. Although practical development engineers can benefit from the knowledge gained by combustion modeling@ they still have to rely ultimately on the experimental development process to arrive at the final design. In the course of such development@ it is important to understand how the hardware changes affect the engine combustion process. In this sense@ practical combustion analysis is a powerful tool. Heat-release analysis@ which is based on actual@ collected cylinder-firing pressure@ is the essence of combustion analysis. A single-zone diagnostic type heat release (zero-dimension model) is used extensively in this book. When used consistently@ this calculation provides useful combustion cycle information. It can be used to understand not only the practical engine performance changes but also the direction for improvement. This book does not attempt to cover all the possible design problems that a diesel engine engineer might meet. Rather@ it demonstrates through many examples how to apply some basic combustion knowledge to understand the changes in engine performance. Practical heat-release analysis is also used to calibrate the specific engine computational model at various stages to shorten the development process. Many of the materials within this text are associated with the medium-speed diesel engine@ since this is the area in which I have the most experience. However@ the methods used and the basic knowledge needed for other types of diesel engines should be similar. This text aims to help readers to analyze their own practical combustion problems@ not necessarily to provide ready solutions. Chapter 1 deals with some basic characteristics of diesel engine combustion process. Chapter 2 describes a commonly used tool to analyze combustion?? heat-release analysis. The usefulness of heat-release analysis and some of the problems associated with acquiring the heat-release information are also included in this chapter. Chapters 3 and 4 discusses the materials that engineers encounter while conducting combustion design. Chapter 5 describes the performance changes that might be encountered in the engine user environment. Finally@ Chapter 6 covers the materials on some of the alternative fuel engines that I have had the opportunity to develop. I am greatly indebted to the General Electric Company@ especially the Transportation Systems division (GETS)@ where I had the opportunity to work on actual combustion problems in detail. In particular@ I am grateful for the longstanding and unreserved support from the previous GETS managers@ Martin J. Hapeman@ John G. Hoffman@ Thomas Hoover@ and Robert F. Fischer. Their support has made my work over the years possible. I am very grateful to Dr. Gong Chen and Dr. Paul Flynn of GETS for their encouragement in writing this book and their review of the original manuscript. I wish to express my deepest thanks to members of the GETS Diesel Engine Laboratory@ especially to Donald Lecker and Richard Beal@ without whose help all the useful data in this book could not have been collected. My gratitude also goes to those previously and presently with GE Corporate Research and Develeopment@ Dr. Gary Leonard@ Dr. Sudhir Savkar@ Roger Johnson@ and Eugene Kimura@ for their support of my work over the years. In addition@ I wish to acknowledge my alma mater@ Tsinghua University of Beijing@ China@ where the foundation of this work began while I was teaching there. My many colleagues and fellow professors there were always helpful and provided me with enlightening discussions. Last@ but not the least@ I would like to thank my wife Jane for her unselfish support and patience for over forty-six years@ without which I would not have had the chance to concentrate on my work. My son and daughter@ Ning and Ann@ have also strongly encouraged me to complete this book and provided me with considerable computer logistics support. I am truly grateful to them all.