Yet another kinetic mechanism for hydrogen combustion

Recent suggestion by Burke and Klippenstein (2017) that chemically termolecular reactions H + O2 + R may significantly affect kinetic pathways under common combustion situations requires careful analysis, since, if included in contemporary kinetic mechanisms, these reactions affect global reactivity and calculated burning velocities of laminar premixed flames. In the view of their impact, a detailed kinetic scheme for hydrogen combustion was revisited to elucidate how to counterbalance enhanced chain termination caused by chemically termolecular reactions in attempt to keep or improve model performance. First, recent experimental and theoretical kinetic studies of hydrogen reactions were analyzed. In the new mechanism four reactions were introduced and three rate constants were updated. These changes, however, significantly reduce calculated burning velocities of H2 + air flames as compared to experimental data and earlier model predictions with the major impact from chemically termolecular reactions. It was then found that implementation of the new theoretical transport database developed by Jasper et al. (2014) significantly improves the performance of the updated kinetic model. The new kinetic mechanism for hydrogen combustion which includes updated kinetics and new transport properties was found in good agreement with the consistent dataset of the burning velocity measurements for hydrogen flames obtained using the heat flux method at atmospheric pressure for which the behavior of the previous model of the author was not satisfactory