Determination of rate parameters based on NH₂ concentration profiles measured in ammonia-doped methane–air flames

The experiments of Rahinov et al. (Combust. Flame, 145 (2006) 105–116) measuring NH₂ concentration profiles in methane–air laminar flat flames doped with ammonia were re-evaluated. The flames were simulated with the FlameMaster code using a modified NOx combustion mechanism of the CRECK Modeling Group. Based on local sensitivity analysis results, Arrhenius parameters A, n, E of reaction steps NH₂ + H = NH + H₂ and NH₃ + OH = NH₂ + H₂O were selected for optimization, which took into account not only the experimental data of Rahinov et al., but also related direct measurements and theoretical determinations as optimization targets. The optimized mechanism described the measured concentration profiles better than the original one, while the new rate parameter values were within the prior uncertainty limits obtained from the evaluation of literature data. The optimization process also provided new posterior uncertainty limits, which are within the prior uncertainty limits.