Kinetic modeling of the H₂/O₂ reaction in high-pressure flames

An updated H₂/O₂ chemical-kinetic model based on that of Li et al. [Int. J. Chem. Kinet. 36 (2004) 566-575] is tested against a wide range of combustion targets that include the previous validation set from Li et al. as well as new measurements that have become available for speciation during H₂ oxidation, H₂/O₂ decomposition, and H ₂O₂ decomposition; ignition delay times in shock tubes and rapid compression machines; and high-pressure and/or low-flame-temperature flame speeds. During the construction of the present model, we have attempted to identify major sources of uncertainties in the model that result in uncertainties in predictions of relevant combustion behavior in order to facilitate further model improvements in the future. Here, we present analyses that suggest that improved characterization of bath-gas mixture behavior in unimolecular decomposition reactions is likely to be necessary to predict ignition delay times and flame speeds accurately. A number of rate constant expressions from recent elementary reaction studies have been incorporated. Predictions using the present model adequately reproduce all the targets used for validation of Li et al. and yield significantly improved agreement with more recent targets that include high-pressure, dilute flames.