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Design and testing of an active heat rejection radiator with digital turn-down capability

Show simple item record Sunada, Eric Birur, Gajanana C. Ganapathi, Gani B. Miller, Jennifer Berisford, Daniel 2015-03-27T22:42:59Z 2015-03-27T22:42:59Z 2010-07-11
dc.identifier.citation AIAA 40th International Conference on Environmental Systems, Barcelona, Spain, July 11-15, 2010 en_US
dc.identifier.clearanceno 10-1888
dc.description.abstract NASA’s proposed lunar lander, Altair, will be exposed to vastly different external environment temperatures. The challenges to the active thermal control system (ATCS) are compounded by unfavorable transients in the internal waste heat dissipation profile: the lowest heat load occurs in the coldest environment while peak loads coincide with the warmest environment. The current baseline for this fluid is a 50/50 inhibited propylene glycol/water mixture with a freeze temperature around -35 oC. While the overall size of the radiator’s heat rejection area is dictated by the worst case hot scenario, a turn-down feature is necessary to tolerate the worst case cold scenario. A radiator with digital turn-down capability is being designed as a robust means to maintain cabin environment and equipment temperatures while minimizing mass and power consumption. It utilizes active valving to isolate and render ineffective any number of parallel flow tubes which span across the ATCS radiator. Several options were assessed in a trade-study to accommodate flow tube isolation and how to deal with the stagnant fluid that would otherwise remain in the tube. Bread-board environmental tests were conducted for options to drain the fluid from a turned-down leg as well an option to allow a leg to freeze/thaw. Each drain option involved a positive displacement gear pump with different methods of providing a pressure head to feed it. Test results showed that a start-up heater used to generate vapor at the tube inlet held the most promise for tube evacuation. Based on these test results and conclusions drawn from the trade-study, a full-scale radiator design is being worked for the Altair mission profile. en_US
dc.description.sponsorship NASA/JPL en_US
dc.language.iso en_US en_US
dc.publisher Pasadena, CA : Jet Propulsion Laboratory, National Aeronautics and Space Administration, 2010 en_US
dc.title Design and testing of an active heat rejection radiator with digital turn-down capability en_US
dc.type Preprint en_US

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