NASA LogoNTRSNTRS - NASA Technical Reports ServerSearchmore_vertCollectionsAboutNewsHelpLogin Back to ResultsOptimized Heat Pipe Backup Cooling System Tested with a Stirling ConvertorIn a Stirling Radioisotope Power System (RPS), heat must be continuously removed from the General Purpose Heat Source (GPHS) modules to maintain the modules and surrounding insulation at acceptable temperatures. The Stirling convertor normally provides this cooling. If the Stirling convertor stops in the current system, the insulation is designed to spoil, preventing damage to the GPHS at the cost of an early termination of the mission. An alkali-metal variable conductance heat pipe (VCHP) can be used to passively allow multiple stops and restarts of the Stirling convertor by bypassing the heat during stops. In a previous NASA Small Business Innovation Research (SBIR) Program, Advanced Cooling Technologies, Inc. (ACT) developed a series of sodium VCHPs as backup cooling systems for the Stirling RPS. In 2012, one of these VCHPs was successfully tested at NASA Glenn Research Center with a Stirling convertor as an Advanced Stirling Radioisotope Generator (ASRG) backup cooling system. The prototype; however, was not optimized and did not reflect the final heat rejection path. ACT through further funding has developed a semioptimized prototype with the finalized heat path for testing at Glenn with a Stirling convertor. The semioptimized system features a two-phase radiator and is significantly smaller and lighter than the prior prototype to reflect a higher level of flight readiness. The VCHP is designed to activate and remove heat from the GPHS during stoppage with a small temperature increase from the nominal vapor temperature. This small temperature increase from nominal is low enough to avoid risking standard ASRG operation and spoiling of the multilayer insulation (MLI). The VCHP passively allows the Stirling convertor to be turned off multiple times during a mission with potentially unlimited off durations. Having the ability to turn the Stirling off allows for the Stirling to be reset and reduces vibrations on the platform during sensitive measurements or procedures. This paper presents the design of the VCHP and its test results with a Stirling convertor at Glenn. Tests were carried for multiple on and off cycles to demonstrate repeatability. The impacts associated with the addition of the VCHP to the system are also addressed in terms of mass and additional heat losses due to the presence of the VCHP.Document ID20160004351Acquisition SourceGlenn Research CenterDocument TypeTechnical Memorandum (TM)AuthorsSchwendeman, Carl L.*(Advanced Cooling Technologies, Inc. Lancaster, PA, United States)*Tarau, Calin*(Advanced Cooling Technologies, Inc. Lancaster, PA, United States)*Schifer, Nicholas A.*(NASA Glenn Research Center Cleveland, OH United States)*Anderson, William G.*(Advanced Cooling Technologies, Inc. Lancaster, PA, United States)*Garner, Scott*(Advanced Cooling Technologies, Inc. Lancaster, PA, United States)*Date AcquiredApril 5, 2016Publication DateMarch 1, 2016Subject CategorySpacecraft Propulsion And PowerMechanical EngineeringReport/Patent NumberAIAA Paper 2015-3983GRC-E-DAA-TN25990NASA/TM-2016-218912E-19168Meeting InformationMeeting: International Energy Conversion Engineering Conference (IECEC)Location: Orlando, FLCountry: United StatesStart Date: July 27, 2015End Date: July 31, 2015Sponsors:American Inst. of Aeronautics and AstronauticsFunding Number(s)CONTRACT_GRANT: NNC14VC86PWBS: WBS 138494.04.18.01.01.01Distribution LimitsPublicCopyrightPublic Use Permitted.KeywordsHeat PipeCoolingStirling EngineAvailable DownloadsNameType20160004351.pdfSTIcloud_downloadcontent_copyvisibilityRelated RecordsIDRelationTitle20160010350See AlsoOptimized Heat Pipe Backup Cooling System Tested with a Stirling Convertorvisibility_offNo Preview Available
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