The objective of this work was to design, build, and vacuum test a high solar absorptance, low infrared emittance solar collector for heat engine and thermal switching applications. Minisatellites proposed by the Applied Physics Laboratory for operation in environments that are subject to radiation threat may utilize a heat engine for power and a thermal bus for thermal control. To achieve this goal, a surface having high solar absorptance and low infrared emittance is needed. At the NASA Glenn Research Center, one concept being pursued to achieve this goal is texturing high thermal conductivity graphite epoxy composites using a directed atomic oxygen beam and then coating the textured surface with a reflective metallic coating.
Coupons were successfully textured, coated, and evaluated. A variety of texturing conditions were explored, and textures were documented by scanning electron microscopy. Copper, gold, silver, iridium, and aluminum coatings were applied, and the highest solar absorptance to infrared emittance ratio was found to be 1.3. A full-sized solar collector was manufactured with this ratio, and the amount of heat collected was observed using an Inconel calorimeter installed in a bench-top vacuum chamber equipped with a solar simulator. Results to date indicate good heat flow through the system, with 9 W of heat flow measured by the calorimeter.
For more information, visit Glenn's Electro-Physics Branch.
Water-cooled Inconel 718 calorimeter and atomic-oxygen-textured solar collector.
Glenn contacts: Dr. Donald A. Jaworske, 216-433-2312, Donald.A.Jaworske@grc.nasa.gov
Author: Dr. Donald A. Jaworske
Headquarters program office: OSS (ATMS)
Programs/Projects: SRF
Last updated June 13, 2001, by Nancy.L.Obryan@nasa.gov
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