Catalytic Combustion in Microchannel for MEMS Power Generation

Catalytic combustion is a promising technique for producing thermal energy in MEMS(Micro Electro-Mechanical Systems) scale electrical power generators. To examine the feasibility and possible benefits of catalytic combustion in MEMS-scale channels, catalytic reactions in small diameter (1 mm) flow reactor tubes at low Reynolds numbers are simulated by using the commercial fluid dynamics code FLUENT coupled to external subroutines that model the surface chemistry at the channel wall. Temperature and major chemical species distributions in the gas phase and on the Pt catalyst surface are obtained for fuel-lean methane/air mixtures as a function of the surface temperature. The catalyst surface area required for complete reaction is estimated by the characteristics of heat release caused by surface reaction. The transition from transport-limited to kinetically-limited reaction is quantified. Results suggest that Pt-catalyzed fuel-lean methane/air mixtures have potential for MEMS power generation applications, provided that the surface temperature can be maintained above about 1000K.