Study on PCCI-DI Combustion in a DME Engine

Experimental investigation on combustion and emission of DME PCCI-DI engine was carried out.The comparisons between the PCCI-DI and the HCCI combustion were also made.Results show that although,in some extend,the power output of DME PCCI-DI engine is limited by knocking,the range of power output is extended significantly in comparison to DME HCCI engine.NOx emission of HCCI engine maintains the very low value,while CO and HC emissions are higher than those of PCCI-DI engine.In addition,the operating range for HCCI is narrower than PCCI-DI engine.The rate of diffusion combustion increases due to the premixed combustion for PCCI-DI operation.PCCI-DI combustion has the lower values in the peak pressure,the rate of pressure rise and the noise.At the present stage of HCCI technology,the PCCI-DI combustion mode is regarded as an alternative approach by using the partial merits of HCCI engine and extending the operation range of HCCI engine.