Heat Recuperator Engineering for an ARL Liquid-Fueled Thermophotovoltaic Power Source Demonstrator

Report No. ARL-TR-7113
Authors: William R Allmon, Dr C Mike Waits, and Dr Erik D Tolmachoff
Date/Pages: September 2014; 28 pages
Abstract: Direct thermal-to-electrical conversion shows promise for small-scale portable power sources using logistics and multiple other fuels. Some potential technologies include thermoelectric, thermophotovoltaic (TPV), and thermionic. For these technologies, thermal efficiency is critical to achieve high energy density and thermal-to-electric conversion efficiency. Combustion can be used to convert fuel to heat a surface, but more than 50% of the thermal power of the combustor can be lost to the exhaust. As a result, heat recuperation is absolutely necessary to reclaim this lost energy. This is accomplished by heating the inlet air and fuel going into the microcombustor using the hot exhaust gases from the microcombustor. The US Army Research Laboratory (ARL) is pursuing a concept demonstration to integrate key components of a combustion-based TPV power source including a microcombustor and heat recuperator. The heat recuperator employs counter flow and microchannel heat transfer to enable high transfer rates in compact form due to a high surface area-to-volume ratio, but challenges exist with pressure drop tradeoffs and fabrication complexity. This report focuses on identifying appropriate materials and fabrication limitations for a microchannel heat recuperator preliminary design.
Distribution: Approved for public release
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Last Update / Reviewed: September 1, 2014