Abstract
The aim of this study is to demonstrate a novel combustion system in which autoignition is induced by spark discharge into a pre-mixture formed during a long ignition delay time in a low compression ratio direct injection diesel engine. An experiment is conducted to investigate the potential of spark discharge on the autoignition process by changing the spark timing, injection timing, equivalence ratio, and fuel amount. The fuel used is lauric methyl ester (LaME), which is a fatty acid methyl ester (FAME) that has relatively high volatility and high ignition quality. The results of our study show that with a volumetric efficiency of 34%, spark-induced compression ignition (SICI) combustion is observed. In this study, the ignition delay time is advanced for about 5 deg. CA, and the ignition timing is controlled by spark timing within 5 deg. CA. In the paper, we also discuss the applicability of starting performance, which is a major problem in low compression ratio diesel engines due to lower temperature at the end of the compression stroke, compared with high compression ratio diesel engines
