REDUCED MECHANISMS FOR PREDICTION of NO2 FORMATION in METHANE-AIR COMBUSTION

Two new 14-step and 16-step reduced mechanisms for methane-air combustion were developed with the emphasis on their capabilities to predict NO2 formation. The systematic reduction was carried out by assuming the quasi-steady state for 26~28 species in the starting mechanism with the help of a automatic mechanism reduction code. The two reduced mechanisms reproduce NO2 formation behaviors obtained with the starting mechanism both in post flame region and in opposed diffusion flames. The promotion of NO2 formation by hydrocarbon additive was also successfully predicted by the reduced chemistry. In addition, the reduced chemistry is accurate in predicting the diffusion flame structure and the ignition delay time.