抄録
In this study, ignition characteristics of dual fuel HCCI were investigated using a single cylinder HCCI engine. Fuels having different low temperature oxidation (LTO) reactivity, methane, propane, isobutane and n-butane, were used as a secondary fuel, and they were added to n-heptane/air mixture. Methane and propane having no LTO mechanism, isobutene having a weak LTO, and n-butane having the highest reactivity among the secondary fuels used in this study. As a result, it was verified that propane retarded the ignition timing more than methane when they were coexisted with n-heptane, although propane has lower octane number than that of methane. Based on chemical kinetic analysis, this is because propane has higher reactivity with OH than methane. Although coexisting alkanes retard LTO, alkanes with LTO mechanism decreases thermal ignition preparation process. The chemical kinetics analysis suggests that higher H2O2 mole fraction at the end of LTO advances the ignition timing.
