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In the past decades, the diesel engines are considered as the major power source, not only because of their high thermal efficiency, high torque output, and easy maintenance; but also due to the improved exhaust emissions reduction technology. In order to increase the thermal efficiency, the low heat rejection ceramic coating engine is one of the possible solutions for future engine manufacturing. Due to the thermal insulating effects of the ceramic material (low thermal conductivity), the cylinder charge and engine components' temperatures are substantially increased. However, the thermal impact problem and the possible high friction characteristics of the new coating material can be deadly to the engine's lifetime. Various non-ceramic and ceramic materials are tested in this research to decide their thermal insulating effects on the engine performance and their downside on the friction and thermal impact problems.

The diesel engine in the past few years has improved its market sharing because the new engine technology has reduced the emissions and the diesel engine has relatively cheaper power cost. Nevertheless, in order to meet more restricted emission standards, the NOx, CO, HC, and particulate emissions must be further reduced. Thus, this study will explore the possible fuel additive technology to further reduce the emissions from the diesel engine. In this study the fuel additives EHN, DTBP, MTBE, DMC, Diglyme, Monoglyme, and Ethanol are added into the diesel fuel with two different dosages. These additives are classified into four categories. It is well believed that the fuel cetane number improver such as DTBP (di-t-butyl peroxide) or EHN (2-ethylhexyl nitrate) can increase the fuel cetane number and thus reduce the emission level.

The purpose of this research is to investigate the combustion characteristics in the diesel engine, the effect of engine operating parameters on the exhaust emissions, and the relationship between exhaust emissions and the engine deposit formation and composition. A YAMAHA ME200F 3-cylinder DI diesel engine is used in this study. A complex procedure is developed in this research to investigate the deposit formation in the piston and cylinder head and the deposit's physical factor (weight, color, etc.) and chemical composition analyses are also performed. In this study, a complete set of gas analyzer (including NOx, total HC, COx, smoke number, and smoke opacity) is used. After continuous operation of engine under different engine load and speed, the cylinder head is dissembled to allow inspection of deposits on the piston and cylinder head. The deposit is separate into soluble and insoluble fractions for weight analysis.