Chemical aspects of the autoignition of hydrocarbonair mixtures

Some aspects of the chemistry of knock in internal combustion engines have been examined within the context of a model of autoignition of hydrocarbonair mixtures at high pressure. The basic model follows an earlier one developed by workers at Shell Research Ltd., which has been refined and extended using reactions and rate parameters which are compatible with the expanding body of kinetics information on the type of elementary processes involved. This model was able to predict moderately well the temperature, fuel, and O 2 dependence of ignition delay time observed in previous experiments in a rapid compression machine, thus providing further support for the validity of the knock mechanisms. Fuel-structure dependent parameters were identified, and first indications of a rational basis for the stability ranking of alkane fuels with respect to autoignition have been found.