Implementation of the NCN pathway of prompt-NO formation in the detailed reaction mechanism

This work presents revised detailed reaction mechanism for small hydrocarbons combustion with possibly full implementation of available kinetic data related to the prompt NO route via NCN. It was demonstrated that model predictions with the rate constant of reaction CH + N2 = NCN + H measured by Vasudevan and co-workers are much higher than experimental concentrations of NO in rich premixed flames at atmospheric pressure. Analysis of the correlations of NO formation with calculated concentrations of C2O radicals strongly supports the inclusion of reaction between C2O and N2 and reduction of the rate constant of reaction between CH and N2. Rate constants of the reactions of NCN consumption were mostly taken from the works of Lin and co-workers. Some of these reactions affect calculated profiles of NCN in flames. Proposed modifications allow accurate prediction of NO formation in lean and rich flames of methane, ethylene, ethane and propane. Agreement of the experiments and the modeling was much improved as compared to the previous Release 0.5 of the Konnov mechanism. Satisfactory agreement with available measurements of NCN radicals in low pressure flames was also demonstrated.