Assessing the predictions of a NO_x kinetic mechanism on recent hydrogen and syngas experimental data

A detailed chemical kinetic mechanism has been developed to describe the pyrolysis and oxidation of the hydrogen/NO_x and syngas/NO_x systems. The thermodynamic data of nitrogenous compounds have been updated based on the study of Bugler et al. (2016). The rate constants of individual elementary reactions associated with the Zeldovich mechanism, the N/O sub-mechanism (NO₂, N₂O and NO₃), the H/N/O sub-mechanism (HNO/HON, HNO₂/HONO and HONO₂) and the NH₃ mechanism (NNH and NH₂OH) have been selected through a synthetic comparison of the data available in the literature and the adoption of the latest available published rate constant data. The proposed mechanism has been validated against a large number of experimental data including pyrolysis histories, ignition delay time data, species profile versus time and temperature and flame speed measurements over a wide range of initial combustion conditions and various experimental devices including shock tubes, flow reactors, jet-stirred reactors and spherical combustion bombs. The simulations of the proposed model have also been compared to those from five recently published kinetic models available in the literature. It was found that although these mechanisms generally reproduced well the data for which they were validated, they did not globally capture the combustion characteristics of all of the hydrogen/NO_x and syngas/NO_x systems. Finally, the proposed model has been used to simulate the formation of NO at practical gas-turbine relevant conditions. A detailed flux analysis has been performed to kinetically explore the NO formation mechanism under various combustion conditions.