Experimental study on HCCI combustion characteristics of n-heptane and iso-octane fuel/air mixture by the use of a rapid compression machine

The purpose of this research is to get fundamental knowledge and to experimentally understand about combustion characteristics of the fuel mixture. This paper shows the Homogeneous Charge Compression Ignition (HCCI) characteristics of a mixture of n-Heptane and iso-Octane in a rapid compression machine. The experimental matrixes cover the n-Heptane mixing ratios, r _n-Heptane, ranging from 0 to 100vol% and the equivalence ratios ranging from 0.1 to 0.6. The experimental study on the effect of mixing fuels focuses on the low temperature oxidation reaction temperatures, T_L, the high temperature oxidation reaction temperatures, T_H, the low temperature oxidation reaction starting times, t_L, the high temperature oxidation reaction starting times, t_H, and the degeneration period. The results show that as r_n-Heptane decreases, t_L and t_H become longer and T_L and T _H increase by 30K. As the equivalence ratio increases, t_L becomes longer but t_H is not a function of equivalence ratio. Moreover, for the partial equivalence ratio of n-Heptane lower than 0.2, t _L, t_H, T_L and T_H are a function of partial equivalence ratio of n-Heptane, while for the partial equivalence ratio of n-Heptane higher than 0.2, there are no effects on any oxidation reaction.