Vibrational nonequilibrium of the HO2 radical in the reaction between hydrogen and oxygen at 1000 < T < 1200 K

A theoretical model of the chemical and vibrational kinetics of high-temperature hydrogen oxidation is presented. The central feature of this model is that it consistently takes into account the vibrational nonequilibrium of the HO 2 radical as the most important intermediate. The basic distinction between the model and the conventional kinetic schemes is that the former does not consider the reaction H + O 2 → O + OH as an elementary event. Calculated data are presented for 1000 < T < 1200 K and 0.9 < P < 2.0 atm, the conditions typical of shock tube experiments. The calculated data show that the nonequilibrium character of the process is the cause of the observed dependence of the “effective rate constant” of the overal reaction H + O 2 → O + OH on experimental conditions. It is demonstrated that this approach is promising from the standpoint of reconciling the predictions of the theoretical model with experimental data obtained by different authors for various compositions and conditions using different methods.