Interaction between heterogeneous and homogeneous reaction of premixed hydrogen-air mixture in a planar catalytic micro-combustor

Hetero-/homogeneous combustion of hydrogen-air mixture in a platinum-coated micro channel was studied by means of three-dimensional (3D) Computational Fluid Dynamics (CFD) model using detailed reaction mechanisms for homogeneous (gas phase) and heterogeneous (catalytic) reactions. The influence of heterogeneous reaction on homogeneous reaction was obtained by discussing the hetero-/homogeneous reaction characteristics, the process and competitiveness of heterogeneous reaction. Intense depletion of fuel and product formation near the inlet has shown that fuel absorption reaction was predominant whiles there was no homogeneous reaction. The free radicals from homogeneous reaction near the catalytic surface were drained, resulting in the interruption of chain reaction. The desorbed product as the third-body promoted the chain terminating reaction to deactivate free radical. The competitiveness value of heterogeneous reaction for capturing fuel was 14.85%, indicating a weak reaction intensity in the catalytic combustor. The heterogeneous reaction presented an inhibition effect on homogeneous reaction but greatly enhanced the combustion efficiency in the micro channel.