1、NASA CR-135069TRW 26148-6004-RU-00HEAT PIPEMATERIALSCOMPATIBILITYJ. E. Eninger,G. L. Fleischman,and E. E. LuedkepreparedforNationalAeronauticsand Space AdministrationLewis ResearchCenterCleveland,Ohio 44135ContractNAS 3-19128kNASA-C_-135069) HEAT PIPE MATERIALS N77-12182COMPATIBILITY Final Report (T
2、RW SystemsGr.oup) 46 p HC _.04/MF A01 CSCL 11F Unclas_3/26 56395January 1976% .jONILSPACE_ARK IIEDONDO BEACH.CALIFORNIA 90178i I1977005239Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-I r l )ti26148-6004-RU-00CTABLEOF CONTENTS SECTION PAGEmmm,_,ABS
3、TRACT ivl.O INTRODUCTION I26148-6004-RU-00t 2.2 PRETESTANALYSISiTo minimizetheeffectof variationsinmaterialcompositionon thegas-generationrate,allsimilarpartsweremanufacturedfromtubeor bar .-.stockof thesameheatnumberandallsimilarwicksfromthesamespoolofwire. All ammoniawas fromthesamecontainerandwas
4、certifiedat 99.998percentpurity(minimum).Pre-testanalyseswerecompletedon thefabricationmaterialsselectedforthisprogram. Photomicrographsof polishedandetchedspecimensweretakenwith an opticalmicroscopeat magnificationsup to 500Xandcomparedwithhandbookmicrostructures.A lotof selected304stainless-steelt
5、ubingwas eliminatedaftermetallurgicalexaminationrevealedthetubingwasnot seamless. Samplesof thealuminumandstainless-steelwerealsoexaminedwitha scanningelectronmicroscopeatmagnificationsup toIO,O00Xto aid in theinterpretationof theopticalmicrographs.All,w_terialscomparedfavorablywith handbookmicrostr
6、uctures.Inaddition,samplesof thematerialsusedin fabricationwere subjectto chemicalanalysis,whichconfirmedthatthematerialsallconformedto handbookspecifications.Analysisof theammoniabyan independentlaboratoryshowedthatintheliquidstateallcontaminants(H2,H20,N2,02,A, C02)were lessthan10 ppm,whichisthe l
7、imitof detectionfortheanalysis. Inthegaseousstate,1.9ppmof hydrogenandO.lppmof nitrogenweredetected. Therestof thecontaminantswerebelowthelimitof detection,which,forthegaseousstate,is 10 ppmforwaterandcarbondioxideandO.lppmforoxygenandargon.2.3 FABRICATION,PROCESS_NDFILLThefabricationandprocessingof
8、 theheatpipesaredescribedin themanufacturingflowchartsand theprocessingspecificationsin theAppendix.ThecleaningprocedurePR2-28-I(summarizedin Table2.2)is a seriesofultrasonlcsolventrinses. Thiswas TRWsstandardheatpipecleaningprocedureat thetlmetheheatpipeswere fabricated.i “8-1977005239-011Provided
9、by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-r r!?26148-6004-RU-00S,_hcequently, a chemical cleaning procedure (CRP7-12 for stainless steel and CRP/-IO for albminum, in the appendix) was prepared as recommendedin 6forevalumtionin thisprogram. On TRW IR ,LI
10、 iPR2-28-IJ US-FILTEREDSOLVENTS. PR13-6-1ULTRASOtlICCLE_NIN FREONTF,HINIHUMOF 15 MINUTES., DRY iN VACUUMOVENAT 212+_FORM!;I.!UMOF 5 MIrIUTEStCULTRSOIiICCL,.ANINACETOIIE,MINIMUMOF 15 MINUTESDRY IN VACUU4UVE;i;T212+-?OeFIFORMItlIHUMOF 5 HilUTESii i i i,i_ MINIMUMOFlS MIt!.UJESIll I IFORMIIIIMUMOF 5 RI
11、NUTES: T _ 1i ii JJ L =: STOREINSUITABLECONTAINERIITable 2.2. AssemblyCleantng Procedure7, -11 - , , J1977005239-014Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-EI= I=_= _ o o o o_ -12-1977005239-015Provided by IHSNot for ResaleNo reproduction or
12、networking permitted without license from IHS-,-,-iI2.4 TESTING_ Exceptwhenthetemperatureprofilesaremeasuredat lowtemperatures,theheatpipesareruncontinuouslyat theirrespectiveoperatingtemperature(seeTables2.1and2.3). Periodicallythe heatinputto theheaterblocks_j“Fted t(maintaintherequiredtemperature
13、.As noncondensablegasis evolvedduringoperationof a heatpipe,it iscarriedto thecondenserendcausinga blockage. Thequantityof noncondensablegas iscalculatedfromthetemperatureprofileof thegas-blockedregion.The profileismeasuredwiththeheatpipeoperatingin a -40Cenvironment,whichis providedby a freezer. By
14、 loweringthevaportemperature,andhenceitspressure,thenoncondensablegasexpandsto filla largervolume,andthusit resultsin a largertemperatureprofile. Thisis illustratedin Figure2-4,wheretheGASPIPEIIcomputerprogramwasusedto generatetwotemperatureprofilesforthesameamountof gas (l.OX lO“7 Ib-moles),butdiff
15、erentoperatingtemperatures.Forcalculationof thequantityof _ds,thecondenserregionisdividedinto N intervals,andthetemperatureat thecenterof the ithintervalisdenoted Ti. Thenumberof moles n of noncondensablegas isgivenby the idealgas lawasNi=lwhere V is thevolumeof eachintervalavailableforgasandvaporan
16、dR is theuniversalgasconstant. Thepartialpressureof gas, Pgi is thediferencebetweenthetotalpressuregivenby thevaporpressurePva of ammoniain theadiabaticsectionand thepartialpressure Pviof vaporin the ith interval. A computerprograms usedto calculatethequantityof gasdirectlyfromthewall-temperaturemea
17、surements.ThemeasuredtemperatureprofilesandcalculatedgasareshowninFigure2-5and2-6fortheparticularheatpipeS/N25,whichis allalumlnumand isoperatedat 80C. Thisdatais typicalIn thatthe initialT gas-generatlonret_ Isrelativelyhigh,andAftera monthit levelsout.t-13-1977005239-016Provided by IHSNot for Resa
18、leNo reproduction or networking permitted without license from IHS-,-,-I, ( ! +_,“ 1 I-,L+-I oi (Lt .+-f,- .r-_C_ _ q.l.- Otl OJ “ (“),S. _ . c- _ 0E .,- _ _ _ 0n_ _ l _ U 4J, c) S.- _ _ _ C_r- 1 _ 1-r- O c“ c- O “_“OI_, n 0 0 u o oo0 0 _ _ 0 n 0 _ I- _/_I- _o o O o o DC_ CD cD D cD o cD cD o CD o_,
19、-_ ,_i _ IU I O_ (“O 0“3, ,-.- I_ OOC CO I_ O l.A“): r_ ,- _ O_ 1.13, ,-.“ ,-,-. N oJ _ ,-o,im ,o u:; oJ ,.- ,J + ,.-Ico ,- e.,L _. _._ _O Q O C2 O: OC_ CD D CD _ D 0 C_ CD 0 CDo_o_ +_ ,-.- ,- ,- ,- ,.-. ,-“I ,- ,- i,- ,- o x _ +* _ _ -_. ,._ _ .I _1._ ,.-t,_ d t_ ,.- c_. ,:l.c,i ,- ,- _ c_ c,) ,_ +
20、c,-)i ,“) ,.,o u:)+ LI, I.- (D. _:= IO _ 8 _,._ CD _D CD O C_ + CD O _0 0 0 _1.) O0 CO _ CO ,.- _ CO + CO O0 CO.s _ o. cO oo_ oO oO co O co ooI!+ +,+ -,.+.,- . - _- _ t- t“ t“ E-i-, i,.,- i,- .i,- .r-“ +i“-“ -i-“_. _.,- 8 oi _ o o o o or=. ., , _ ._ o ol o o _ o o o,_ _=- I E .0 O 0 CD _P- CD _DE _.
21、 m_ I “P“ _ I .,-, t._ 03r _ C_+- I.-._L I _ _ I I I I I I I I i +_“_ OP“ 0_I_)-14,-1977005239-017Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-O-15-1977005239-018Provided by IHSNot for ResaleNo reproduction or networking permitted without license
22、from IHS-,-,-26148-6004-RU-00I I I I I I I I I i _.m,-.-?1977005239-019Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-!Iir26148-6004-RU-00An overallgasgenerationrateof 5.8x lO“lOIbm/day wascalculatedby a least-squaresfitof a straightlineto thedataof
23、 Figure2-6past3u days. Thedataforall of theheatpipesare summarizedin Table2.4.Detaileddataforeachpipeat eachmeasurementintervalis presentedinTableA-l in theAppendix.k.5 POST-TESTANALYSISPost-testanalyseswereperformedon oneof each typeheatpipetested: AI/SSwick (S/N8),Al/Alwick (S/N27),and SS/SSwick (
24、S/N39).HeatpipeS/N12wasalsoanalyzedto determinethesourceof a leakwhichcausedthepipeto failin test.Massspectrometrygasanalyseswereperformedon ammoniasamplesfromheatpipesS/N8 and S/N27 to determinethenoncondensablegasorgasesgeneratedduringtesting. Valveswereattachedto thetwopipesto alloweasy removalof
25、 thegassamples. Thiswas doneby placingthefllltubesina gloveboxfilledwithhelium,andthenchillingtheheatpipesin liquidnitrogento 77K. Thefilltubeswere cutoffwithatubingcutterandvalvesattached. Thetotaltimeforattachingeachvalvewas approximatelyoneminute.Gasandliquidsamplestakenfrompipes8 and27 wereanaly
26、zedbyan independenttestinglaboratory(datasheetin Appendix).The resultsshowthathydrogen,as expected,is thenoncondensablegasand thatallotherimpuritiesarebelowlO ppmexceptnitrogen. The nitrogenwasapparentlyintroducedintotheheatpipesduringthe valveinstallation.Allfourheatpipeswere subsequentlyemptiedof
27、ammonia,opened,andvisuallyinspectedfor internalsurfacedamage. Openingwasdoneby cuttingoff theendcaps,removingthewicks,andcuttingthepipesaxiallyintotwosections. The cutsweremadeon a bandsaw. The inter-nalsurfacesof theheatpipeswere visuallyinspectedundera microscope.-17-W _ 1977005239-020Provided by
28、IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-!26148-6004-RU-00Theonlyheatpipewithanysignificantchangeto theinternalsurfacewas S/N8 (AI/SSwick),wherecorrosionandpittingoccur“redtheentirelengthof theheatpipe. Damagewas aboutequalin allsectionsof the: heatpipe.
29、A solidwhiteprecipitate,probablyAl OH,wasdepositedinvariousspotsintheevaporator,adiabatic,andcondensersections.HeatpipeS/N27, (Al/Alwick)andheatpipe,S/N39, (SS/Z_wick)hadverylittlepittingor corrosion,andoveralltheinternalsurfacelookedveryclean. HeatpipeS/N12was foundto be leakingfromacircumferential
30、crackapproximatelyImmlongat theadiabaticend of theevaporator.-18-1977005239-021Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-i !(3.0 DATAANALYSIS3.1 THEEFFECTOF OPERATINGTEMPERATUREON GASGENERATIONWehadexpected,basedon previousstudieswithnickel/wat
31、er4andstainless-steel/methanol5heatpipes,thatthegasgenerationwou|dbestronglyandpositivelycorrelatedwithoperatingtemperature.From oTable2.4 we seethat thisis notnecessarilythecase. Forthethreesetsofaluminum-walledheatpipeswith stainless-steelwicksthatwere; operatedat 40C(S/N4-6),80C (S/N7-9),andlOOC(
32、S/NI0-2),thetrendis exactlyopposite. At theendof thetestperiodtheyallhavegeneratedapproximatelythe sameamountof gas;however,thegas-generationratewas lowestfor thelOOCoperatingtemperatureandhighestfor40C.Theall-aluminumand all-stainlesssteelheatpipes,on theotherhand,didhavetheirlowestgasgenerationrat
33、eat 40C (S/N22-24andS/N31-33);however,in bothcasesthe80Cpipes(S/N25-27andS/N34-36)generatedgasata h_gherratethanthelOOCpipes(S/N28-30andS/N 37-39). Thegasgenerationintheall-stainless-steelpipeswasgenerallyso low,however,itwasat thedetectionlimitand,therefore_differencesintheratesfortheall-stainless-
34、steelpipesare notsignificant.Theinconsistencyof thecorrelationbetweengas-generationratesandtemperaturesuggeststhattwoopposingprocessesareoccurring.Oneclearlyis thechemicalreactionthatgeneratesthegas,whichis certaintobe positivelycorrelatedwith temperature.Thesecondis passivationof themetalsurfaceswi
35、tha filmof corrosionproducts. Evidentlypassivationcanpro:eedmoreeffectivelyor to a greaterextentat higheroperatingtemperaturesandthusexplainsthelowergenerationratesat|OOCthanat 80C (alsolowerratesat 80Cthan40Cforthealuminum/stainless-steelheat pipes).-19-i I1977005239-022Provided by IHSNot for Resal
36、eNo reproduction or networking permitted without license from IHS-,-,-! I26148-6004-RU-003.2 THEEFFECTOF THEPRESENCEOF WATERMoreunexpectedresultswere foundin thedatafromthoseheatpipesusedto studytheeffectof thepresenceof water. HeatpipesS/N20-21,forexample,hadI/2%wateraddedwith thefinalchargeof ammo
37、nia.Althoughthesepipesgeneratedby farthemostgasby theendof thetestthananyof theothers,thegasgenerationoccurredprimarilyin thefirstmonthof operation.Thereafter,thesepipeshada loweraveragegas-generationratethananyof theotheraluminum-walledpipes.Thevacuum-bake-outstepis usedin theprocessingof thealumin
38、um-walledheatpipesprimarilyto driveoffwater. To assesstheeffectofthisamountof water,heatpipesS/N18-19did nothavea bake-out.HeatpipeS/N 18performedroughlythesameas thepipesthathadthebake-outstep,exceptfora slightlyhighergas-generationrate. HeatpipeS/N 19,however,producedsurprisingresults:thequantityo
39、f gasit generatedand thegenerationrateare roughlya factorof ten lessthantherestof thealuminum-walledheatpipes.Theevidencefromboththeheatpipeswithoutthebake-outstepandwithwaterintentionallyaddedpointstowardwaterplayinga keyrole ineffectivepassivationof thealuminum. In thecaseof S/N 19,we canconjectur
40、ethatwithoutthebake-outtherewas sufficientwaterforeffectivepassivationduringthehigh-temperaturerefluxes. Thegasgeneratedduringthispassivationis purgedbeforethefinalcharge. HeatpipeS/N18 maynothavehadsufficientwaterforthepassivation.Inthecaseof SIN20-21,thepassivationoccursduringoperationwith thefina
41、lcharge,and hencethegasgeneratedduringpassivatlonremainedinthepipesduringthelifetest.3.3 THE EFFECTOF WICKSURFACEAREAON GASGENERATIONThreesetsof heatpipes,S/NI-3,7-9,and 13-15,wereoperatedat80Candusedto assesstheeffectof wicksurfaceareaon generationrate.S/NI-3hadnowlck (zeroarea),S/N7-9hadthenominal
42、stainless-steelwick (O.O044-in-dia.wire,81.1%porosity),andS/N13-15hada high-surface-areawick (O.O034-in-dia.wire,8:.2%porosity),whichhas30%-20-i977005239-023Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-26148-6004-RU-00moreareathannominal. Theavera
43、geamountof gasgeneratedandthegas-gzneratiunratesforthethreesetsof heatpipesare roughl)the same(seeTable2.4). Thisresultsuggeststhatthereis sufficientsurfaceareayenerationevenwithouta wickandthattherateandtotalgasquantityiscontrolledby thefluidcharge,andnottneavailableinteriorsurfacearea.3.4 MATERIAL
44、SAFFECTON GASGENERATIONAs expected,theall-stainless-steelheatpipeshadby farshe leastamountof gas. We alsoexpectedthatthegalvaniccouplebetweenstainlesssteelandaluminumwouldcausethealuminum/stainless-steelheatpipestogenerateconsiderablymoregasthantheall-aluminumheatpipes. Thiswastrueonlyforthepipesope
45、ratedat the lowtemperatureof 40C. At 80 andI00C,thegasgenerationin theall-aluminumandaluminum/stainless-steelwere comparable.In fact,at thesetemperaturestherateswere higherfortheall-aluminumpipes,buttheamountof gasgeneratedwas less.Theseresultssuggestthatthegalvaniccoupleeffectivelycontributestopass
46、ivationat 80Candabove(hence,thelowerrateof generationfor thealuminum/stainless-steelcombination).The lowertemperatureof 40Csignificantlyretardsgasgenerationonlyin theabsenceof thegalvaniccouple(hence,therelativelysmallquantityof gasand lowratefor theall-aluminumheatpipesat thelowertemperature).3.5 T
47、HEEFFECTOF THETYPEOF CLEANINGPROCEDUREAND VACUUMFIRINGFORSTAINLESSSTEELONTHEGASGENERATIONRATEHeatpipesS/N148-149are identicalto S/N25-27(bothsetsareallaluminumandwereoperatedat 80C)exceptS/N148-gwerechemicallycleanedratherthansol_antcleaned. AlthoughS/N148-9were addedto thetestmatrix(hencetheyhadonl
48、ybeenon testfor140dayscomparedto approxi-matelyZ40daysfortheothers),thechemicallycleanedpipesgeneratedsignificantly less gas and at a lower rate than the solvent cleaned pipes.HeatpipesS/N 150-151arestalnless-steelheatpipesthatwere alsochemlcallycleanedratherthansolventcleanedand,inaddition,thehigh-tE,Bperaturevacuum-firlngstepwasdeleted. Heatpi
