Design and Analysis of a Syngas Catalytic Combustor for Micro Electrical Mechanical Systems (MEMS)

Abstract

Abstract In this work, a catalytic combustor for micro electrical mechanical system using renewable syngas was designed and analysed using Direct Numerical Simulation (DNS) in conjunction with finite rate chemistry. The effect of catalyst (rhodium, palladium, and rhodium), shape and packing of the catalyst and operating conditions (e.g., inlet temperature and velocity, fuel/air ratio, H2 content in the fuel mixture) on combustion efficiency and pressure drop were studied. Findings demonstrate that the catalyst in the shape of intalox saddle resulted in the bed effectiveness factor (An ideal reactor effectiveness factor is 1 which 0.5 is equivalent to 100% combustion efficiency and 0.5 is from 0% pressure drop at the combustor outlet) 0.93, while the packing geometry of the catalyst has negligible impact on the operation of the reactor. Analysis under different operating conditions reveals that the designed reactor can operate effectively with syngas of varying compositions. The combustion mainly takes place on the surface of the catalyst without gas phase reaction. The analyses of Damköhler number demonstrated that the timescale of chemical reactions is at the same order of magnitude for concentration of hydroxyl radicals (OH) over the entire length of the reactor, suggesting a uniform combustion.