Reduction of large detailed chemical kinetic mechanisms for autoignition using joint analyses of reaction rates and sensitivities

This study describes a new technique of reduction of detailed mechanisms for autoignition. It is based on two analysis methods. An analysis of reaction rates is coupled to an analysis of reaction sensitivity for the detection of redundant reactions. Thresholds associated with the two analyses have a great influence on the size and efficiency of the reduced mechanism. Rules of selection of the thresholds are defined. The reduction technique has been successfully applied to detailed autoignition mechanisms of two reference hydrocarbons: n-heptane and isooctane. The efficiency of the technique and the ability of the reduced mechanisms to reproduce well the results generated by the full mechanism are discussed. A speedup of calculations by a factor of 5-9 for n-heptane mechanism and by a factor of 16.7 for isooctane mechanism is obtained without losing accuracy of the prediction of autoignition delay times and concentrations of intermediate species. (c) 2007 Wiley Periodicals, Inc.