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The boiling point curve of fatty acid methyl esters (FAME), or biodiesel fuel, can be adapted to that of diesel fuel by breaking FAME down into a low-molecular structure using a cross-metathesis reaction with a short-chain olefin. Reformulated FAME by a metathesis reaction consists mainly of medium-chain olefins and fatty acid methyl esters. In the present study, the engine performance and exhaust emissions from reformulated FAME were investigated through engine bench tests. Surrogate fuels made from typical chemical components of reformulated FAME were used to clarify the effects of respective components upon combustion. Surrogate fuels were made by mixing 1-decene, 1-tetradecene, methyl laurate, methyl palmitate, and methyl oleate to simulate the boiling point, oxygen mass concentration, and calorific value of reformed biodiesel of waste cooking oil methyl ester (WME). A single-cylinder diesel engine equipped with common-rail-type injection system was used.

The main aim of this study is to investigate the effect of NO and NO2 on the combustion characteristics such as pressure development and combustion phasing in natural gas HCCI engine. A secondary aim is to demonstrate a method of obtaining a significant sensitizing effect on methane oxidation reaction from small amounts of NOx. Experiments were conducted using a rapid compression-expansion machine that was constructed from a single-cylinder diesel engine. First, the sensitizing effect of NO and NO2 on the HCCI combustion of natural gas was investigated in a case where NOx was uniformly mixed into a charge. Obtained results show that the auto-ignition timing is significantly advanced and an acute heat release is promoted by adding either NO or NO2.

In this study, the influence of compression ratio on engine performance and variations of auto-ignition timing in each cylinder were evaluated in a 4-cycle multi-cylinder natural gas engine with PCCI combustion system. In experiment, the compression ratio was systematically changed from 19 to 25. From the result, it was clarified that an increase in compression ratio makes not only the improvement of engine output and fuel economy but also the reduction of NOx emission, even though the mechanical loss is increased. Simultaneously, the variation of auto-ignition timing in each cylinder can also be reduced.

In this study, it was attempted to operate the 4-cycle multi cylinder natural gas engine introduced PCCI combustion system without electric heater for intake air heating. In experiment, by optimization of the compression ratio and in addition to the control of spark ignition timing, the engine could be operated using only intake air heating with coolant water. The results showed that the suppression of the auto-ignition timing variations among cylinders owing to the independent spark timing control of each cylinder leads to the improvement of engine output, fuel economy and exhaust emissions. Furthermore, this paper describes the engine starting and corresponding change of engine load on electric demand on generator. The stable operation could be achieved by using spark ignition, controlling of excess air ratio and intake air temperature during change the engine load from idle to rated power.