In the present study,the detailed reaction mechanisms were developed and Chemkin 4.1.1 was implemented to predict the formation of pollutant species in compressed natural gas(CNG)fired internal combustion(IC)engine.The proposed mechanisms were developed by coupling the EXGAS(an automatic mechanism generation tool for alkane oxidation)mechanisms with the Leed's NOx mechanism(version 2.0).The simulation results of each proposed mechanism were validated by the experimental measurements for profiles of temperature,pressure and pollutant species(CO,NOx).The rate of production analysis of each mechanism identified the important reactions in each mechanism which contributed to the formation of pollutant species.In spite of some discrepancies,the experimental measurements indicate that Mechanism-Ⅳ (consisting of 208 reactions and 78 species)showed closer agreement for each of the predicted profiles of temperature,pressure and pollutant species(CO,NOx).
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