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Thermal performance of a multi-evaporator loop heat pipe with thermal masses and thermal electrical coolers

Show simple item record Ku, Jentung Ottenstein, Laura Birur, Gajanana 2006-03-27T23:38:30Z 2006-03-27T23:38:30Z 2004-09-21
dc.identifier.citation 13th International Heat Pipe Conference, Shanghai, China, September 21-25 2004. en
dc.identifier.clearanceno 04-1958
dc.description.abstract This paper describes thermal performance of a loop heat pipe (LHP) with two evaporators and two condensers in ambient testing. Each evaporator has an outer diameter of 15mm and a length of 76mm, and has an integral compensation chamber (CC). An aluminum mass of 500 grams is attached to each evaporator to simulate the instrument mass. A thermal electric cooler (TEC) is installed on each CC to provide heating as well as cooling for CC temperature control. A flow regulator is installed in the condenser section to prevent vapor from going back to the evaporators in the event that one of condenser is fully utilized. Ammonia was used ad the working fluid. Tests conducted included start-up, power cycle, heat load sharing, sink temperature cycle, operating temperature control with TECs, and capillary limit tests. Experimental data showed that the loop could start with a heat load of less than 1OW even with added thermal masses. The loop operated stably with even and uneven evaporator heat loads, and even and uneven condenser sink temperatures. The operating temperature could be controlled within ±0.5K of the set point temperature using either or both TECs, and the required TEC control heater power was less than 2W under most test conditions. Heat load sharing between the two evaporators was also successfully demonstrated. The loop had a heat transport capability of 120W to 140W, and could recover from a dry-out when the heat load was reduced. The 500-gram aluminum mass on each evaporator had a negligible effect on the loop operation. Existing LHPs servicing the orbiting spacecraft have a single evaporator with an outer diameter of about 25mm. Important performance characteristics demonstrated by this LHP included: 1) Operation of an LHP with 15mm diameter evaporators; 2) Robustness and reliability of an LHP with multiple evaporators and multiple condensers under various test conditions; 3) Heat load sharing among LHP evaporators; 4) Effectiveness of TECs in controlling the LHP operating temperature; and 5) Effectiveness of the flow regulator in preventing vapor from going back the evaporators. en
dc.description.sponsorship NASA/JPL en
dc.format.extent 1182086 bytes
dc.format.mimetype application/pdf
dc.language.iso en_US en
dc.publisher Pasadena, CA : Jet Propulsion Laboratory, National Aeronautics and Space Administration, 2004 en
dc.subject two-phase heat transfer en
dc.subject loop heat pipes en
dc.subject multiple evaporators en
dc.subject multiple condensers en
dc.subject thermal control en
dc.subject thermal systems architecture en
dc.title Thermal performance of a multi-evaporator loop heat pipe with thermal masses and thermal electrical coolers en
dc.type Preprint en

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