4733 A Process of Thermal Flame Appearance in HCCI Engine
Details
The transition process from cool flame to thermal flame in homogeneous charge compression ignition is discussed It was confirmed in a simulation that an autoignition process exhibits three peaks in an Anhenius plot of heat release by a difference of key reaction or reaction mechanism so that low temperature oxidation, H_2O_2 decomposition reaction and H+O_2 reaction forming OH+O. A shoulder of H_2O_2 peak exhibits linear shape and an activation energy agrees with that of H_2O_2 decomposition under various fuels. In experiments, although broadened high temperature peak obscures the intermediate peak, other features obtained by simulations were observed From these observations, transition process from cool flame to thermal flame can be explained by thermal explosion theory in which rate determining reaction is H_2O_2 decomposition.
