Multi-Step Ignition Mechanism of Gasoline Surrogate Fuel

Abstract

In the previous experimental and computational studies, gasoline surrogate fuel, such as binary or ternary fuel mixtures of n-heptane, iso-octane, and toluene, have been used for the purpose of analyzing the chemical kinetics in internal combustion engines. A part of these studies reported that multiple heat release has been observed other than the combination of low and high temperature oxidation heat release which was well known as two-stage ignition. In the present computational study, we have analyzed the ignition characteristics of n-heptane/toluene binary mixtures using our revised detailed chemical kinetic model of gasoline surrogate fuel. Extra heat release between low temperature oxidation and thermal ignition period, and two-step thermal ignition were observed at low equivalence ratio conditions. These heat releases are caused by the part of the thermal heat releases which failed to raise the temperatures high enough to be dominated by the chain branching reaction, H₂O2 = 2OH and H + O2 = O + OH.