Effect of Cavity Coupling Factors of Opposed Counter-Flow Microcombustor on the Methane-Fueled Catalytic Combustion Characteristics

Abstract

In this work, numerical investigations of methane catalytic combustion in the opposed counter-flow microcombustor are conducted under various inlet velocities, equivalence ratios, and geometric parameters. The results indicate that the high temperature zone is mainly located at the front and middle parts of the reaction zone. With the increase of inlet velocity, both methane conversion and exhaust gas temperature decrease, while the methane concentration in the downstream area increases. Its maximum velocity limit is 2.9 m/s. Moreover, temperature step zones of opposed counter-flow are obviously located at the front and middle parts with different equivalence ratios. The combustion efficiency decreases slowly with the increase of equivalence ratios. More importantly, critical values about the geometric parameters are determined for keeping better thermal performance. It is concluded that inlet velocity limit and methane conversion rate can be significantly increased and the temperature distribution is more uniform via reducing inlet width L2 and inlet height H, increasing the length of the downstream parts L1 and the downstream entrance length L3. In general, the opposed counter-flow microcombustor with optimized structure has better combustion stability. This design offers another way for developing the opposed counter-flow microcombustor.