Experiments on a novel design of a microscale hydrogen combustor heat exchanger (μCHX) are presented. The experimental study demonstrates proof of concept for the design and examines the effect of varying selected fluidic and geometric conditions on the overall efficiency of the μCHX. A unit cell consisting of a combustion channel, a recuperator channel and an oil heat exchange channel is tested. This unit cell device has the potential to be scaled up to a reactor in the tens of kilowatts range required for practical heating applications. Combusted gases flow back through the device in a cross-flow configuration between the combustion channel and the oil channel, preheating the inlet gas stream and transferring heat to the oil. Platinum has been selectively deposited on the stainless steel inner wall of the combustion channel to facilitate heterogeneous combustion of hydrogen and air. The performance of the μCHX is characterized based on a global efficiency, defined as the ratio of the energy transferred to the oil stream compared to the energy rate of the supplied hydrogen gas. The effects of residence time, equivalence ratio, and average oil temperature, have been investigated. Hydrogen conversion rates in excess of 95 percent were achieved for residence times between 20–25 ms. Efficiencies in excess of 90 percent were obtained for equivalence ratios greater than 0.5 and for average oil temperatures between 63 °C and 105 °C. Experiments were also performed on two different lengths of catalyst with a higher efficiency being demonstrated by the catalyst with the longer length.

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