An investigation of the effect of fuels stratification of DME and n- butane on reducing pressure rise rate in a HCCI engine using chemiluminescence imaging

The purpose of this study was to gain a better understanding of the effect of fuel stratification by using chemiluminescence imaging. In order to investigate the fundamental aspects of fuel stratification, Di-methyl ether (DME) that has large heat release in LTR and n-Butane that has small heat release in LTR were used as test fuels. By using these fuels, investigations were conducted on five mixing conditions depending on DME or «-Butane and homogeneity or stratification as parameters. It is found that combustion phasing is changed by the condition of charging fuel, and maximum pressure rise rate is also changed by the condition of charging fuel. In addition, from chemiluminescence imaging, in the condition of charging fuel that achieves the lowest maximum pressure rise rate, chemiluminescence start timing is dispersed and its duration is longer.