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Virginia Tech
ARPA-EKick-offMeeting:REEACHProgram-27January2021db-1
ARPA-EKick-offMeeting:EnergyStorageandPowerGenerationSystemIntegrationPanel
BriefOverview:Mission-andAircraft-levelThermalManagementSystems
Dr.MichaelvonSpakovskyRobertE.Hord,Jr.ProfessorinMechanicalEngineering
MechanicalEngineeringDepartment(0170)CenterforEnergySystemsResearch
VirginiaTechBlacksburg,VA24060
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Virginia Tech AircraftThermalManagementSubsystem(TMS):
Source/Sink(EnergyStorage)Issues
ARPA-EKick-offMeeting:REEACHProgram-27January2021db-2
q Numerousheatsources:― Cabin/cockpit― Air-cooledavionics― Liquid-cooledavionics― Engine― EPS+(generators,motors,
pumps,compressors,e-actuators,powernetwork,controllers,etc.)
q Limitedheatsinks(energystorage):― Ramair― Engine― Environment
q MEA/AEA,DEW,andISRaddingtoandincreasingthesizeandintensitiesofheatsources
q Survivability,compositematerials,etc.areeliminatingheatsinksorshrinkingtheircapacities ClearedforPublicRelease:88ABW-2014-4186/RQ-14-664,3SEPT2014
ColdPAOLoop
HotPAOLoop
EnvironmentalControl
Sub-system
VaporCompressionSub-SystemFuelLoop
Sub-System
RamAir
RamAir
Cabin/Cockpit
AvionicsEPS+
AvionicsEPS+
Propulsion Sub-system
heatsourceheatsink
TMSBoundary
Environment
activecooling
intermediateheatsink
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Virginia Tech TMSTrendsandTechnicalIssues
ARPA-EKick-offMeeting:REEACHProgram-27January2021db-3
q Integratedaircraft-andmission-levelTMSdesigniscriticaldueto§ increasedheatloads§ decreasedthermalenergystorageand
rejectioncapabilities
q Nonlinearheatloadandsinktrendsdrivenby§ MEAsandAEAs§ increasedfuelefficienciesleadingtoless
on-boardfuel§ increasedengineefficienciesleadingto
higherT’sandhigherheatloads§ high-Pfuelpumpswithhigherheatloads§ needforgreatermaneuverability(e.g.,
fueldraulicactuatorsforthrustvectoring)§ compositematerials(e.g.,forless
weight,survivability,etc.)§ DirectedEnergyWeapons(DEWs)and
highpowerISRsensors
Criticalityoftheincreasedheatloadfortypicalstate-of-the-artmilitaryaircraft(ClearedforPublicRelease,AFRLRZ09-0609)
§ safety(i.e.,fuelassinknotavailableforcommercialaircraftandbecomingmorelimitedformilitaryaircraft)
q TMSbecomingmainelectricpowerconsum-erandelectricalpowersubsystem(EPS)requiringgreaterTMScapabilities
ClearedforPublicRelease:88ABW-2014-4186/RQ-14-664,3SEPT2014
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Virginia Tech AircraftThermalManagementSystem(TMS):
NeedforMission-/Aircraft-levelIntegratedDesign
ARPA-EKick-offMeeting:REEACHProgram-27January2021db-4
AFS-A PS ECS VC/PAOS FLS ES CHS OLS FCS
Weight (lbm) 14980.8 5418.3 1297.1 1608.1 491.5 929.5 325.3 37.8 429.3
% empty weight 58.7% 21.2% 5.1% 6.3% 1.9% 3.6% 1.3% 0.1% 1.7%
OptimizedAAFTMSrepresentsonly13%to11.5%ofthetotalemptyweightoftheaircraftyetplaysacriticalroleinensuringthermallimitsarenotbreached
Mission-andaircraft-leveloptimizedsupersonicair-to-air
fighter(AAF)results:1st
ILGOiteration
Source:adaptedfromK.Smith,2009,M.S.Thesis,VirginiaTech.
Wetasopposedtodryweight
values
AFS-A PS ECS VC/PAOS FLS ES CHS OLS FCS
Weight (lbm) 9628.4 3678.8 749.5 909.9 280.4 899.5 325.3 37.8 404.4
% empty weight 56.9% 21.7% 4.4% 5.4% 1.7% 5.3% 1.9% 0.2% 2.4%
Mission-andaircraft-leveloptimizedsupersonicAAFresults:
Globaloptimum
OptimizingtheTMSindependentlyofotheraircraftsub-systemsandthemissionwillsignificantlyaltertheTMSresultsandmaycausethermallimitsto
bebreached
Remainingwithinthermallimitsmakesthedifferencebetweenachievingamissionornot
ClearedforPublicRelease:88ABW-2014-4186/RQ-14-664,3SEPT2014
AAFandTMSreduction:53.4%
and43%
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Virginia Tech Aircraft-andMission-levelMDO:
OptimalUseofFLSasHeatSink
Fueltanktemperatureversustimeovertheentiremissionfortheoptimalvehicle
toff–takeoffscc1–1stsubsoniccruise/climbcap–combatairpatrolcacc–combataccelerationscc2–2ndsubsoniccruise/climbloit–loiter
298
300
302
304
306
308
310
312
314
0 300 600 900 1200 1500 1800 2100 2400 2700 3000
Time (Sec)
Tem
pera
ture
(K)
With AFS degrees of freedom Without AFS degrees of freedom
scc1
cap
cacc
scc2
loit
toff
Source:adaptedfromD.Rancruel,2002,M.S.Thesis,VirginiaTech.
ARPA-EKick-offMeeting:REEACHProgram-27January2021db-5
ClearedforPublicRelease:88ABW-2014-4186/RQ-14-664,3SEPT2014
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Virginia Tech TMSSynergieswiththe
ElectricalPowerSubsystem(EPS)
ARPA-EKick-offMeeting:REEACHProgram-27January2021db-6
q EPS-TMSdesignoptimizationwouldtakeadvantageofbenefitsresultingfromthermal-electricalenergymanagementto§ reducepeakpowerdemands§ reduceoverallinstalledenergyconversion,
storage,andtransportcapacities
q EPS-TMSdesignoptimizationwouldquantifythebenefitsofsynergiestoimproveTMS(VCSandACM)performancevia,e.g.,§ electronicstocontrolthepressuresatwhich
compressorscutinandout§ electronicexpansionvalvesfortemperature
control§ separatehighandlowpressureelectronic
switchestopreventcompressors,etc.fromoperatingoutsideofsafelimits
§ electroniccontrolstoadjustcompressoroperationfordifferingcoolingloadsandreducedenergyconsumption
©2007TheBoeingCompany
q EPS-TMSdesignoptimizationwouldquantifythebenefitsofsynergiesfortheEPS§ forlocalizedtemperaturecontrolof
powerelectronics(e.g.,thermoelectricgeneratorsandcoolers,heatpipes,…)
§ foraircraftmonitoringandpredictivemaintenance(e.g.,engineandaircraftskinoverheating,deicing,etc.)
§ forelectricallydrivenECSs(e.g.,usingfuelcells,…)
ClearedforPublicRelease:88ABW-2014-4186/RQ-14-664,3SEPT2014
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Virginia Tech EPSLocalCoolingTechniques
db-7ARPA-EKick-offMeeting:REEACHProgram-27January2021
ManylocalcoolingchoicesfortheEPS,allofwhichmustultimatelyinterfacewiththeTMS,particularlyduetosurvivabilityrequirementsandtheuseofcompositematerials:
q Heatspreadingq Aircooling
§ piezofans§ syntheticjetcooling(topright)§ nano-lightning(bottomleft)
q LiquidCooling§ heatpipes§ coldplates(topleft)§ microchannels§ electrohydrodynamic(bottom
right)§ electrowetting
q Liquidmetalcooling
q Spraycoolingq Liquidjetimpingementq Thermo-chemical
accumulators
q Immersioncoolingq Solidstatecooling
§ thermoelectric§ superlattice§ heterostructure§ thermionic§ thermotunneling Source:adaptedfromDr.WernerJ.A.Dahm,ASU,Thermal
Sciences&MaterialsWorkshop,Kettering,OH,16-17August2011.
ClearedforPublicRelease:88ABW-2014-4186/RQ-14-664,3SEPT2014
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Virginia Tech HeatPipesforHighExternalThermalLoads
8
q ExamplesofheatpipesforthermallymanagingtheheatloadsatleadingedgesincludeD-Shapedheatpipes,I-coreheatpipes,andheatspreaders.
q D-shapedandI-coreheatpipesarebuiltdirectlyintothematerialthatformstheleadingedge(seebelow).Thedisadvantageisthatitcanleadtodeformationoftheheatpipesduringthemanufacturingprocesswhentheleading-edgematerialisbentintoitsfinalshape.
q Twotypesofheatspreadersareshownbelow,aperiodicverticalI-truss-system(left)andaperiodictriangular-truss-system(right)
q Bothprovidestructuralsupporttotheleadingedge,increasingthebendingstiffnessandcompressivestrength,whilethetriangular-trusssystemallowsforflowinmultipledirections,facilitatingtheflowofvapor. Source:S.D.Kasen,ThermalManagement
atHypersonicLeadingEdges,Ph.D.dissertation,UniversityofVirginia(2013)
ARPA-EKick-offMeeting:REEACHProgram-27January2021
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Virginia Tech PhaseChangeMaterialsforHighInternal
ThermalLoadsq PCMenergystoragecanaddresscriticalthermalloadsonhighperformanceaircraftsinceit
providesameansforcoolingincreasedthermalloadsduetothe§ Increaseduseofcompositesontheaircraftskin;§ Increasedpowerrequirementsfornewsystems(e.g.,MEA/AEA,DEWs,ISRsensors,etc.);§ Reducedornoorrestrictedfuelonboard.
q PCMsarecontainedintankswithinteriormatricesmadeofhighconductingmaterials(e.g.,carbonfoam)tohelpdistributeheattothePCM.
Source:Reed,W.C.,vonSpakovsky,M.R.,andRaj,P.,ComparisonofHeatExchangerandThermalEnergyStorageDesignsforAircraftThermalManagementSystems,AIAASciTec(2016).
Pentadecane Hexadecane Octadecane
EffectiveThermalConductivity W/m/K 220.16 165.12 165.12
EffectiveDensity kg/m^3 1054.4 1057.1 1098.3
PhysicalparametersofPCMmaterials.
Pentadecane Hexadecane Octadecane
MeltTemperature °C 10 18 27ThermalConductivity W/m/K 0.2 0.15 0.15
Density kg/m^3 768 770 800LatentHeatofFusion kJ/kg 205 237 244
PhysicalparametersofPCM-carbonfoamcomposite.
ARPA-EKick-offMeeting:REEACHProgram-27January2021
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Virginia Tech SomeConclusions
ARPA-EKick-offMeeting:REEACHProgram-27January2021db-10
q Numberofheatsourceshasalwaysbeenlarge,whilethenumberofheatsinkshasalwaysbeenlimited
q MEA/AEA,DEW,ISR,increasedengineefficiencies,high-Pfuelpumps,theneedforgreatermaneuverability,etc.areaddingtoandincreasinginahighlynon-linearfashionthesizeandintensitiesofheatsources
q Survivability,compositematerials,increasedfuelefficiencies,safety,etc.areeliminatingheatsinksorshrinkingtheircapacities
q Reachingthermallimitsarerealthreatstothecompletionofmissionsandtothedesignandconstructionofcomplexmissions
q TMSisbecomingthemainelectricpowerconsumerandtheEPSisrequiringgreaterTMScapabilities
q Using“dryweight”toassessTMSviabilitymustbereplacedwithanassessmentof“wetweight”inordertoaddresstheseriousissueofthermallimits.
q Assessmentmustbedoneasearlyinthedesignprocessaspossible,i.e.,duringtheconceptualdesignphase
q Theneedforamission-andaircraft-levelMDA/MDOconceptualdesignframeworkisacute.
ClearedforPublicRelease:88ABW-2014-4186/RQ-14-664,3SEPT2014