Analysis of catalytic heat transfer for a multi-species gas mixture

Abstract

Stagnation point catalytic heat transfer model for a multi-species gas mixture has been developed in this work. The analysis extends the existing tertiary gas mixture catalytic model that assumes thermochemical equilibrium at the edge of a chemically frozen boundary layer. The catalytic heat transfer is computed numerically by solving the governing equations with matrix diagonalization and shooting methods. The present model is applied to compute the heat transfer for both tertiary gas mixture O-O2-Ar and quinary gas mixture O-O2-N-N2-Ar. For the case of the tertiary gas mixture, the present model predicts in the finite-catalytic region, the stagnation-point heat transfer due to recombination is similar with that of the existing models of Goulard and Park. In the highly-catalytic region, however, noticeable differences are observed owing to how the species mass fraction at the wall is computed. Unlike the Goulard approach treating the oxygen and nitrogen as a single recombination efficiency, in the case of the quinary gas mixture, the oxygen recombination efficiency needs to be decoupled with that of nitrogen. The present global model for the tertiary gas mixture is also compared with the Computational Fluid Dynamics (CFD) approach. The results suggest that the present model predicts a similar diffusive stagnation heat transfer to that of the CFD approach, within some acceptable range, when a zero backward reaction rate constant is assumed in the chemical reaction modeling.