Influence of Compression Ratio on Homogenous Charge Compression Ignition Combustion

Abstract

The HCCI concept is a promising combustion process for simultaneously obtaining low Nox and PM emissions and high thermal efficiency. With the engine technology currently available, however, the HCCI operating region is limited and compression ignition timing is difficult to control. Meanwhile, DME has attracted interest as a potential alternative fuel for compression ignition engines. This fuel has a negative temperature coefficient region in which the ignition delay is not shortened even if the compression-induced temperature rises. DME is thus characterized as producing multi-stage heat release through both low- and high-temperature combustion. This paper discusses the relationship between the compression ratio and these observed tendencies.