Performance Characterization of a Microscale Integrated Combustor Recuperator Oil Heat Exchanger

A two-dimensional numerical model of an integrated microscale hydrogen-air combustor, recuperator, and oil heat exchanger is presented. The recuperator is used to preheat the incoming reactant gases entering the combustor. Heterogeneous catalytic combustion occurs on the walls of the microchannel in the presence of platinum catalyst. The maximum oil temperature was constrained based on the properties of the fluid used. The recuperator gas outlet temperature was constrained to be larger than the saturation temperature for water to avoid condensation in the exhaust gas stream. The performance of the combustor is documented for variations in geometric and fluidic parameters. The geometric parameters include the length and location of the catalyst bed, and the length of the device. Varied fluidic parameters include the oil inlet temperature, flow rates of oil and reactants, and the equivalence ratio of the reactants. For the range of parameters studied, results indicate that increasing the catalytic surface length as well as the channel length increases the efficiency.