Abstract:  Homogeneous charge induced ignition (HCII) combustion mode can achieve higher thermal efficiency than gasoline SI combustion with lower soot emissions than diesel CI combustion. The combustion characteristics of HCII were investigated on a modified high-pressure common rail single-cylinder diesel engine. The concept of low temperature combustion was used to reduce NOx emissions with a two stage diesel injection strategy used to improve violent combustion of HCII for high  load conditions. The results show that HCII combustion mode has the characteristics of rapid heat release and short combustion duration at a high constant volume ratio. HCII combustion mode leads to complete combustion at richer fuel/air ratios, breaking through the rich limit of direct injection diesel engines for a higher power density. Combined with exhaust gas recirculation (EGR), HCII can achieve low temperature combustion with very low NOx and soot emissions. The two stage diesel injection can reduce the peak heat release rate, thus effectively inhibiting the maximum pressure rise rate.

Key words: homogeneous charge induced ignition (HCII), combustion, exhaust gas recirculation (EGR), thermal efficiency, emissions