A Comparative Study of Chemical-Kinetic Mechanisms for Combustion of Methane/Hydrogen/Air Mixtures

Eighteen chemical kinetic mechanisms for combustion of methane/hydrogen mixtures are compared for various burning conditions. The 18 mechanisms include eight detailed mechanisms, nine reduced mechanisms, and one global mechanism. Six of the reduced mechanisms are derived in this study. In the methane/hydrogen mixture, the blending ratio of hydrogen increases from 0 to 100% by 20% point in mole fraction. Calculated ignition delay times and laminar burning velocities are compared with available experimental data over the wide ranges of pressure and equivalence ratio as variables, respectively. Ignition delay times with NO2 are also evaluated by several mechanisms to compare their prediction accuracy for NOx emission. The aim of this study is to provide information for the purpose of choice of particular kinetic mechanism to obtain accurate results at a reasonable computational cost. The results show that although the reduced reaction mechanisms developed in this study have a narrower applicable range for predicting ignition delay times with hydrogen blending, they present higher accuracy in calculating laminar burning velocities and NOx emissions.