DETAILED STRUCTURE STUDY OF A LOW-PRESSURE, STOICHIOMETRIC H2 N2O/AR FLAME/

A combined experimental and detailed chemical modeling study has been performed on a 20 torr, stoichiometric H-2/N2O/Ar burner stabilized fl ame. Species concentration profiles were measured using molecular beam sampling with mass spectrometric detection and laser-induced fluoresc ence, while temperature profiles were measured with coated Pt/Pt-Rh(10 %) thermocouples. The burned gases of the flame contain about 2 mol.% of NO and H-2, a concentration of approximately ten times more than th at of their equilibrium. This formation prevents full energy release o f the system within or near the flame zone. Experimental flame profile s of the major species, H-2, N2O, N2, and H2O, as well as the minor sp ecies, NO, O2, OH, H, O, and NH, are presented and compared to calcula ted profiles generated by PREMIX, a one-dimensional premixed laminar f lame code. The chemical mechanism used in the flame code was derived f rom a critical literature review and consists of 38 reactions and 14 s pecies. Rate and sensitivity analyses performed reveal the intricacies of the mechanism as well as reactions important in the modeling of th e experimental results. Several key reactions, including N2O + OH = HO 2 + N2 and N2O + H = NO + NH, whose rate coefficients have been contro versial, are discussed in detail. In addition, the importance of vario us collision partners in the key initiation step, N2O + M = N2 + O + M , is presented and discussed.