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A critical parameter to compact and portable power generation is gravimetric energy density (energy per unit weight), in terms of which fuels fare much better than conventional batteries. As a result, there has recently been a flurry of, sometimes questionable, activities on micro/meso-scale fuel-based power generation. This article discusses an approach to mesoscale electric power production relying on a clean and efficient combustor coupled with a free-piston Stirling engine. First, the design and development of a catalytic burner will be reviewed. Its main components are: a multiplexed electrospray to disperse jet propulsion fuel (JP-8), a stack of catalytically coated grids through which fuel conversion and heat release is achieved cleanly and efficiently, and a recuperator to improve the system thermodynamic efficiency. The combustor has a volume of tens of cm3 and operates at JP-8 flow rates on the order of tens of g/hr, and equivalence ratios varying in the 0.35-0.70 range. The combustor was interfaced with the 35 We Sunpower (Athens, OH) free-piston Stirling engine to achieve power generation with a gross fuel-electric efficiency of 21%. With design optimization, 21% efficiency net of parasitic losses should be achievable, with an energy density on the order of 1,000–2,000 W-hr/kg, depending on fuel autonomy.Copyright © 2005 by ASME |
