Multistage Mechanism of Thermal Decomposition of Hydrogen Azide
T. A. Bolshova1, A. A. Paletsky1, O. P. Korobeinichev1, V. D. Knyazev2
1Voevodsky Institute of Chemical Kinetics and Combustion, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia
2Catholic University of America, Washington, USA
Keywords: hydrogen azide, mechanism of thermal decomposition, modeling, superadiabatic temperature, flame structure, flame propagation velocity
Abstract
A kinetic mechanism for combustion of hydrogen azide (HN3) comprising 61 reactions and 14 flame species (H2, H, N, NH, NH2, NNH, NH3, HN3, N3, N2H2, N 2H3, N2H4, N2, and Ar) was developed and tested. The CHEMKIN software was used to calculate the flame speed at a pressure of 50 torr in mixtures of HN3 with various diluents (N2 and Ar), as well as the self-ignition parameters of HN3 (temperature and pressure) at a fixed ignition delay. The modeling results of the flame structure of HN3/N2 mixtures show that at a 25–100% concentration of HN3 in the mixture, the maximum temperature in the flame front is 25–940 K higher than the adiabatic temperature of the combustible mixture. Analysis of the mechanism shows that burning velocity of a HN3/N2 mixture at a pressure of 50 torr is described by the Zel'dovich–Frank-Kamenetskii theory under the assumption that the burn rate controlling reaction is HN3 + M = N2 + NH + M (M = HN3) provided that its rate constant is determined at a superadiabatic flame temperature. The developed mechanism can be used to describe the combustion and thermal decomposition of systems containing HN3.
|
