Comparisons of Performances and Emissions of Dual Combustion Mode Engine

The spark ignition(SI) and homogeneous charge compression ignition(HCCI) were conducted alternatively in a modified single cylinder engine.The operation regions of the two combustion modes and the knock and/or misfire boundary were defined.Experimental results show that the maximum load in HCCI mode is about half to that in SI mode load at the same speed solely diluted by preheated air.Compared with SI,the charge is lean in the operation region of HCCI,and NOx emission decreases greatly.Decreasing load leads to leaner charge and lower combustion temperature in the cylinder,but slightly higher in CO and HC emissions.