Effects analysis on the catalytic combustion and heat transfer performance enhancement of a non-premixed hydrogen/air micro combustor

In this work, a type of non-premixed hydrogen/air micro combustor is designed for the application of microthermophotovoltaic (MTPV) systems. The micro combustor is presented with a backward-facing step and unique inlet shape to enhance the mixing performance and flame stabilization. The combustion, flow, and heat transfer characteristics of non-premixed hydrogen/air combustion in micro combustors with/without catalyst segment are numerically investigated. The results indicate that the homogeneous reaction is obviously weakened in the catalytic combustor, but a higher and more uniform outer wall temperature is obtained, and the outer wall temperature difference can be decreased by up to 28%. The flow characteristics of gaseous mixture in the catalytic combustor are better than those in the non-catalytic combustor. When the inlet velocity is 10 m/s, the average flow velocity and pressure loss of the catalytic combustor are decreased by up to 5.6% and 250 Pa, respectively. Furthermore, the heat of reaction and total heat flux at the gas-solid interface of the catalytic combustor are obviously higher and lower than those of the non-catalytic combustor, and the outer wall heat loss ratio is increased by up to 0.59% when the inlet velocity is 10 m/s. All in all, it can be concluded that adopting catalytic combustion to the micro combustor is extremely suitable for the application of MTPV systems.