N2O production characteristics of strain stabilized premixed laminar ammonia/hydrogen/air premixed flames in lean conditions

Product gas characteristics of ammonia/hydrogen/air laminar premixed flames stabilized in stagnation flows were experimentally and numerically studied. Although the maximum value of NO mole fraction increased compared with pure ammonia/air flames, the trade-off relationship between NO and unburnt NH3 were also observed. In addition, N2O production for very lean conditions were observed. To clarify the N2O production mechanism in detail, numerical simulation modelling was employed using CHEMKIN software. Sensitivity analysis suggested that the reactions of (R58) NH+NO = N2O+H, (R105) N2O+H = N2+OH, and (R106) N2O(+M) = N2+O(+M) play an important role in N2O production. Product gas characteristics of N2O were numerically investigated for various stagnation plane temperatures and the equivalence ratios. The reaction rate of R106 decreases for low stagnation plane temperature cases and small equivalence ratios. It was considered that the decrease in the reaction rate of R106 decreased the reduction rate of N2O to N2, and thus large amount of N2O were detected. Also, the N2O amount decreased when the stagnation plane temperatures were sufficiently high. This also suggested that the N2O production may be restricted by a decrease in the heat loss in an ammonia-fueled combustor