Abstract
This study investigated the mechanism producing the multi-stage heat release behavior of a supercharged HCCI engine operated on blended fuels of DME and methane. These aspects were investigated by making spectroscopic measurements of in-cylinder gas, FTIR analysis of intermediate products and by conducting chemical kinetic analyses. The results revealed that the DME is mainly consumed during cool flame and accumulate HCHO. In addition, in the first-stage heat release of the main combustion, HCHO is consumed and CO is produced. Meanwhile, methane is not appreciably consumed in the first-stage heat release of the main combustion and consumed just prior to the second-stage heat release. That explains why the heat release of the hot flame occurred in two distinct stages.