Potential of fuel stratification for reducing pressure rise rate in HCCI engines fueled with DME/n-Butane

We investigated the efficacy of fuel stratification in a pre-mixture of Di-methyl ether and n-Butane, which have different auto-ignition characteristics, for reducing the pressure rise rate of homogeneous charge compression ignition engines. A new chemical reaction model was created by mixing DME and n-Butane and compared to existing chemical reaction models to verify the effects. The rate of maximum pressure rise depends on mixture ratio. When DME was charged with stratification and n-butane was charged with homogeneity, the maximum pressure rise rate was the lowest. The calculations were performed using the SENKIN application of CHEMKIN-II.