Abstract
Homogeneous Charge Compression Ignition (HCCI) combustion has attracted much interest as a combustion system that can achieve both low emissions and high efficiency. However, combustion proceeds extremely rapidly in the HCCI process due to simultaneous ignition at multiple locations in the cylinder. That characteristic makes it necessary to moderate the rapidity of HCCI combustion under high-load operation. In the present study, a blended fuel of dimethyl ether (DME) and methane, with each component having different ignition characteristics, and a supercharged HCCI engine were used to investigate the effects of the ignition timing and the ratio of the intake air volume and injected heat value on the heat release characteristics of the hot flame. The results suggest that a certain ratio of injected heat value and intake air volume is required to induce two-stage heat release from the hot flame when a blended fuel of DME and methane is used.
