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. NO_x, 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.