Comparison of the effect of heat release and products from heterogeneous reaction on homogeneous combustion of H_2/O_2 mixture in the catalytic micro combustor

摘要

Numerical simulation was carried out to investigate the hetero-/homogeneous combustion of stoichiometric H-2/O-2 premixed flames in a platinum-coated planar micro channel. Three-dimensional Computational Fluid Dynamics (CFD) models with detailed reaction mechanisms for homogeneous (gas phase, G) and heterogeneous (catalytic, C) reactions were adopted. The effects of the heat released and products from heterogeneous reaction (CR) on the homogeneous reaction (GR) were analyzed and compared systematically. In the presence of additional released heat, the flame temperature, intermediate concentrations and product yield increased, especially near the inner wall. The promotion effect of heat released from the CR on the GR was indicated, and it mainly reflected in the increase of chemical reaction rate and fuel consumption. When the heat released and the products from the CR were added simultaneously, the flame temperature and species (OH) concentration were still low as compared with the model without addition. The inhibition effect of the product on the GR was larger than the promotion effect of the additional heat on the GR. The increase in the chemical reaction rate and fuel conversion rate demonstrated that, the heat released from the CR could improve the combustion efficiency of the micro combustor. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.