学士暖通专业全套毕业设计10

毕业设计外文翻译 -PAGE24-河北建筑工程学院毕业设计（论文）外文资料翻译系别：城市建设系专业：建筑环境与设备工程班级：建环083姓名：韩宗潭学号：2010405321指导教师评语：签字：年月日外文原文（复印件）Determinationofunidirectionalheattransfercoefficientduringunsteady-statesolidificationatmetalcasting–chillinterfaceTurkeyReceived9October2004;accepted30March2005Availableonline11May2005AbstractInthisstudy,theinterfacialheattransfercoefficient(IHTC)forverticallyupwardunidirectionalsolidificationofaeutecticAl–Sicastingonwatercooledcopperandsteelchillswasmeasuredduringsolidification.Afinitedifferencemethod(FDM)wasusedforsolutionoftheinverseheatconductionproblem(IHCP).Sixcomputerguidedthermocoupleswereconnectedwiththechillandcasting,andthetime–temperaturedatawererecordedautomatically.Thethermocoupleswereplaced,locatedsymmetrically,at5mm,37.5mmand75mmfromtheinterface.Asthelateralsurfacesareverywellheatisolated,theunidirectionalsolidificationprocessstartsverticallyupwardattheinterfacesurface.Themeasuredtime–temperaturedatafileswereusedbyaFDMusinganexplicittechnique.Aheatflowcomputerprogramhasbeenwrittentoestimatethetransientmetal–chillIHTCintheIHCP.Theexperimentalandcalculatedtemperatureshaveshownexcellentagreement.TheIHTCduringverticallyupwardunidirectionalsolidificationofanAl–Sicastingoncopperandsteelchillshavevariedbetweenabout19–9.5kW/m2Kand6.5–5kW/m2K,respectively.EnergyConversionandManagement47(2006)19–341.IntroductionThesubjectofmetal–chillinterfacialheattransfer,becauseofitsimportantinfluenceonthesolidificationrateofmetalcastings,hasbeeninvestigatedbyseveralpreviousstudies.SomeresearchershavestudiedtheheattransfermechanismofcastingstofindtheinfluencingfactorsontheIHTCaswellasthemacroheattransfervalues.Inthesepreviousworks,theIHTChasbeendependentonmanyfactorsincludingthepresenceandthicknessofsurfacecoatings,castingsurfaceorientationandcastingsize,chillormoldmaterial,appliedpressure,alloytypeandcomposition,liquidalloysurfacetension,moldandchillpreheat,alloysuperheatandchillsurfaceroughness[1–11].Theeffectsofthedirectionofgravityinrelationtotheinterfacehavebeenexaminedbyinvestigationwiththechillplacedonthebottom,toporsideofthemold[1].Anexactestimationoftheheattransferduringtheliquidalloysolidificationinacastingmolddependsondeterminationoftheboundaryconditionsduringthesolidification,propertiesofthemold,propertiesofthecastingalloytemperaturedistributioninthecasting.Duringthesolidification,theseparametersarechangingasafunctionoftemperatureandtime.Forthepurposeofaccuratemodelingofsolidificationprocesses,itisrequiredthatcorrectboundaryconditionsshouldbesetup[12–14].Estimationoftheheattransfercoefficientinametalcasting–chillinterfaceisusuallycalculatedfromtime–temperaturedatameasuredduringthesolidificationofaunidirectionalchilledexperimentalcasting.Thecastingalloyandchillmaterialusedforexperimentalcastingare,generally,madeofsomematerialsandalloysonwhichaccurateknowledgeoftheirthermophysicalbehaviorisknown,suchasaluminum,copper,ironandsteal[15,16].Heattransfercoefficientsdifferdependingonthedifferentexperimentalconditionsandcastingalloysused[4].Reviewingtheliterature,ithasbeenfoundthattherearebasicallytwomethodstomeasuretheIHTC[17,18].Oneistomeasurethesizeofthegapformedbetweenthemetalcastingandthechillandcorrelatethisgapsizewiththeheattransfercoefficient[19–21].TheothermethodistoconducttemperaturemeasurementsinthecastingandinthechillatseveraldesignatedlocationsanduseaninversemethodtoderivetheIHTC[1,5,14].Someresearchershavestudiedtheproblemofmeasuringthetransientmetal–chillIHTCduringunidirectionalsolidification.Thesestudiesshowthattheheattransfercoefficientbecomesahighvalueintheinitialstageofsolidificationandthendeclinestoalowsteadyvaluebecausethecastingcontractsfromthechillsurface,creatinganinterfacialgap[1,12,17,22,23].Ithasbeenfoundthattheheattransfercoefficientshavehighervalueswhensolidificationisverticallyupwardthanwhensolidificationiseitherverticallydownwardorhorizontal[1].Thelossofheatwhenametalfirstcomesintocontactwiththemoldisregulatednotonlybytheheatstoragecapacityofthemoldmaterialbutalsobytheheattransferconditionswithinthemetalitselfandparticularlyatthemetal–chillinterface.Santosdeterminedthatthesolidbodiesareonlyincontactatisolatedpoints,andtheactualareaofcontactisonlyasmallfractionofthenominalarea[12].VariousprocessingparametersandtheireffectontheIHTChavebeenexaminedbyseveralresearchers.Intheliterature,severalresearchershavestudiedtheproblemofdeterminingtheIHTCatthemetal–chillinterfaceforsolidifyingaluminumalloysincopper,steelorcastironmoldsandhaveprovidedsomewidelydivergentvalues.Thesevalueshavebeenreportedfromashighas20kW/m2Ktolessthan1kW/m2K[1,10,24–35].Theobjectiveofourworkistodeterminethemetal–chillIHTCduringtheunidirectionalsolidificationverticallyupwardofacylindricalAl–SialloycastingonthewatercooledsurfaceofcopperandsteelchillsandtocomparetheIHTCofthecopperandsteelchills.Inthecourseofthework,aheatflowcomputerprogramhasbeenwrittentoestimatethetransientmetal–chillIHTCintheIHCP.2.ExperimentalprocedureTheschematicrepresentationoftheexperimentalsetupconnectedtothedataloggerandanalysissystem,thecastingarrangementandthepositionofthethermocouplesusedintheunidirectionalsolidificationexperimentsisshowninFig.1.TwogroupsofexperimentsforevaluationoftheIHTCareconductedforaliquidalloy(Al–Si)onwatercooledsteelandcopperchillsattheFacultyofTechnologyinGaziUniversity,Ankara,Turkey.Liquidmetaliscastinaceramicmoldmadeofanalumina-silicaterefractorytubeoflength290mm,internaldiameter28mmandwallthickness10mm.Therefractorytubeisimbeddedinceramicwoolof20mmthicknessforimprovedlateralheatisolation.Thecylindricalchill(copperorsteel)oflength90mmisinsertedintoacylindricalmoldasshowninFig.1.Sixchromel-alumelthermocoupleswerecenteredatthecommoncylindricalaxesofthechillandcastingintheradialdirection(seeFig.1).Theyareplacedsymmetricallyandlocatedat5mm,37.5mmand75mmfromthecasting–chillinterface.Allthermocoupleswereconnectedbycablestoadataloggerinterfacedwithacomputer.ThethermophysicalpropertiesofthecastingandchillmaterialsselectedforourexperimentsaresummarizedinTable1[36,37].TheexperimentsareperformedwithanAl–Sialloy,aeutecticcomposition,havingaverynarrowfreezingrange.Forbenchmarkingpurposes,copperandlowcarbonsteelmetalsareusedforthechillbodymaterialbecauseoftheirverywellknownthermophysicalbehavior.Theverticalsolidificationapparatusisdesignedtopermitheatextractiononlythroughthewatercooledbottom.Thelateralsurfacesareverywellheatisolated,sothattheunidirectionalsolidificationprocessstartsverticallyupwardattheinterfacesurface.Thealloywasmeltedinanelectricresistanceovenuntilthemoltenmetalalloyreachedapredeterminedtemperature(980K),abovetheirmeltingtemperatureof849K,andthencooledtoroomtemperatureinthemold.Calibratedthermocoupleswereused.Sixcomputerguidedthermocoupleswereconnectedwiththechillandcasting,andthetime–temperaturedatawererecordedautomatically.Thedatafromthethermocouples,readinthechillandcastingareusedtoplotthetime-dependentexperimentaltemperatureprofiles.Themeasuredtime–temperaturedatafileswereusedtofindthecorrectboundaryconditionsaswellastocorrelatethetemperaturesderivedfromtheFDMusinganexplicittechnique,whichwasincorporatedintheheatflowcomputerprogramwrittentoestimatethetransientmetal–chillIHTC,asexplainedinChapter3.TheflowchartshowninFig.2givesanoverviewofthesolutionprocedure.3.DeterminationofheattransfercoefficientInourstudy,theIHTCduringthesolidificationprocessiscalculatedbysolvingtheIHCPusingaFDM.Experimentsareconductedtodeterminetheunknowntemperaturesandtheheatfluxattheinterfacebetweenthecastingandchill.Thetime–temperaturedataarereproducedtobeusedtoevaluatetheboundaryconditions.Theheatfluxacrossthemetal–chillinterfacecanbedescribedbyamacroscopicaveragemetal–chillIHTC(h).Onecanwritewhere_qistheaverageheatfluxacrossthemetal–chillinterfaceinW/m2andTCandTMarethecalculatedinterfacetemperaturesofthecastingmetalsurfaceandthechillsurface,respectively.Theheatfluxforboththecastingandchillinterfaceswerecalculatedfromthetemperaturegradientatthesurfaceandsub-surfacenodesasfollows:wherekisthethermalconductivityofthecastingorchillmaterials,W/mK.Then,themacroscopicaverageIHTC(h)wascalculatedfromEq.(1).3.1.Mathematicalformulationofheattransfercoefficient3.1.1.HeatflowinthechillWithadequateinsulationofthechillandcastingchamber,theheatflowthroughthecastingcanbereasonablyapproximatedasaonedimensionalheattransferproblem.Unsteadystate(transient)conductionheattransferinaonedimensionalbodycanbedescribedbywhereTisthetemperature,tisthetimeandxistheCartesiancoordinate.Thetermaisthethermaldiffusivityoftheconductingmaterial,wherekisthethermalconductivity,qisthedensityandcisthespecificheatcapacity.3.1.2.HeatflowinthecastingWhentreatingthecastingheatflow,thegoverningequationissimilartoEq.(3),butthetermqisincludedonthelefthandsideofEq.(3).Wecanwritetheheattransferequationforsolidifyingmetalsasbelow.ThetermqonthelefthandsideofEq.(5)isaheatsourceterm,whichisincorporatedtoaccountforthelatentheatofsolidification,givenbywherelisthelatentheatoffusionandfsisthesolidfractioninthecasting.Thefstermisdeterminedasbelow,Eq.(7).TheterminEq.(6)canberelatedtotemperatureasfollowsSubstitutionofEq.(8)intoEq.(6)givesSubstitutionofEq.(9)intoEq.(5)givesThisequationcanberearrangedasOnecandefinec0asanapparentspecificheatduringthesolidification.Then,Eq.(11)canbewrittenas3.1.3.FinitedifferenceformulationAnalyticalmethodsmaybeused,incertaincases,toevaluateexactmathematicalsolutionstosteady,oneortwodimensionalconductionproblems.However,thesesolutionscanbegeneratedforanassortmentofsimplegeometriesandboundaryconditions,andtheyarewelldocumentedintheliterature.Ontheotherhand,analyticalsolutionstotransientproblemsarerestrictedtosimplegeometriesandboundaryconditions.Inthisrespect,inmanycases,thegeometryandboundaryconditionsprecludetheuseofanalyticaltechniquesandrecoursemustbemadetoFDM.SomeresearchersdevelopedanumericalmodelbasedonaFDMforsimulatingsolidificationbehavior[38–40].Inthepresentwork,thisproblemhasbeenapproachedinonedimensionalgeometryforaregionwithafinitedimensionLshowninFig.3asfollows:Theregion(06x6L)isdividedintoMequalsizemeshes.msubscriptsareusedtodesignatethexlocationofthediscretenodalpointsinFig.3.Besidesbeingdiscretizedinspace,theproblemmustalsobediscretizedintime.Theintegerpisintroducedforthispurpose:ThefinitedifferenceapproximationtothetimederivativesofEq.(3)andthesametypeofEq.(12)isexpressedasThesuperscriptpisusedtodenotethetimedependenceofT,andthetimederivativeisexpressedintermsofthedifferenceintemperaturesassociatedwiththenew(p+1)andtheprevious(p)timesteps.Eqs.(3)and(12)aresolvedusinganexplicitFDMforthechillandcastingbywhichcanberearrangedas,whereFoisafinitedifferenceformoftheFouriernumber,Eq.(17)isexplicitbecausetheunknownnodaltemperaturesforthenewtimearedeterminedexclusivelybytheknownnodaltemperaturesattheprevioustime.Hence,calculationoftheunknowntemperaturesisstraightforward.Sincethetemperatureofeachinteriornodeisknownatt=0(p=0)fromtheprescribedinitialconditions,thecalculationbeginsatt=Dt(p=1),whereEq.(17)isappliedtoeachinteriornodetodetermineitstemperature.Withthetemperaturesknownfort=Dt,theappropriatefinitedifferenceequationisthenappliedateachnodetofindthetemperaturesatt=2Dt(p=2).Inthisway,thetransienttemperaturedistributionisobtainedbymarchingoutintime,usingintervalsofDt.TheaccuracyofthefinitedifferencesolutionmaybeimprovedbydecreasingthevaluesofDxandDt.Ofcourse,thenumberofinteriornodalpointsthatmustbeconsideredincreaseswithsmallermeshintervalwidthDx,andthenumberoftimeintervalsrequiredtocarrythesolutiontoaprescribedfinaltimeincreaseswithdecreasingtimeintervalDt.Hence,thecomputationtimeincreaseswithfinerresolutionsDxandDt.Eq.(17)mustbewrittenforboththecastingandthechillelements,separately.Forconvergenceofthecalculation,theelementsizeandtimesteparetobechosenunderconsiderationofThetermsinEq.(18),DxandDt,refertothespaceandtimeincrementsusedinthecalculations.Inthiswork,thedifferentialelementsareselectedasDx=0.5mmand,consequently,Dt60.0017sforboththecastingandthechill,complyingwithFo.BoundaryconditionsandsolutionInthepresentwork,theinitialtemperatureandboundaryconditionsarechosenasfollows:wherethetemperaturesusedfortheboundaryconditions,Ti,TmandTm,areobtainedduringtheexperiments,measuredintwosymmetricallylocatedthermocouplesinthechillandcastingatL=75mmfromthemetal–chillinterface.Thefirsttemperaturesrecordedbythethermocouplesplaced,symmetrically,75mmfromthemetalcasting–chillinterfacewereusedasinitialtemperatures,Eq.(20),att=0inthecastingandchill,respectively.Thetemperaturesfromthesethermocoupleswerealsousedasboundaryconditionsatlatertimesinthefinitedifferencecalculations,Eqs.(21)and(22),respectively.Theboundaryconditionsattheinterfacewereobtainedbyassuminguniformsurfacetemperaturesoverthesurfacesofthecastingandchill.Thetemperaturesarereadfromthethermocouplesevery0.5s,definedasthetimeperiodofmeasurements.Thecalculatedtemperatures,5mmfromtheinterfaceinthecastingandthechill,respectively,werecomparedwiththemeasuredtemperaturesobtainedatthesamepoints.Forthispurpose,theactuallocationofthethermocouplebetweentwoadjacentnodeswasdetermined,andthetemperaturewasinterpolatedlinearlybetweenthem.Thesupposedsurfacetemperaturesatthecastingandchillinterfacewerethenmodified,andthefinitedifferencecalculationfortheprevious0.5stimeintervalwasrepeated.Theaccuracyofthenumericalsimulationshasbeensettoagreeby±0.1Kwiththemeasuredtemperaturesforthepointsatthe5mmsymmetricaldistancesfromtheinterfaceinthecastingandthechill.Inthisway,areliabletemperaturefieldhasbeendeterminedthatgavethesurfacetemperaturesofthecastingandthechillattheinterfacewithintheselectedaccuracyof±0.1K.4.ResultsanddiscussionsTemperatureswereexperimentallymeasuredinsixlocations:inthechillandcasting,symmetricallyat5mm,37.5mmand75mmfromthecasting–chillinterface,respectively.TheyareshowninFig.4togetherwiththecalculatedtemperaturesfollowingfromthenumericalsimulationinthechill(TM)andcasting(TC)interfaceoftheeutecticAl–Sicastingandthewatercooledsteelchill.Fig.5showsthesamedatafortheeutecticAl–Sicastingandthewatercooledcopperchill.Thevariationsofthetemperaturefieldinthecourseoftheexperimentscanbefollowedforboththesteelandcopperchill,inFigs.4and5,andareingoodagreementwiththethermophysicallaws.InordertochecktheprecisionattainedbytheFDM,thecalculatedtemperaturesinthecastingatapoint37.5mmfromthecasting–chillinterfacewerecomparedwiththetemperaturesmeasuredatthispointinaperiodof0.5s.Themeasuredandcalculatedtemperaturesinthemid-points(37.5mm)fromtheinterfaceinthechillandcastingaremonitoredtocontrolthereliabilityofthecorrelationbetweenthemeasurementsandthenumericalcalculation.Inthechillmid-point,whereonlyheatconductiongoverns,theagreementofthemeasurementsandcalculationsisexcellent,withlessthan1–2Kdifference,consideringtheaccuracylimitsofthethermocouplesemployed.Ontheotherhand,thephasechangingeventsinthecastingcomplicatethecalculationoftemperatures.Intheliterature,temperaturedifferences<±20Kbetweenthemeasurementsandnumericalcalculationinthecastingareaccepted[3].Inthepresentstudy,goodagreementbetweenthemeasurementsandnumericalcalculationhasbeenattained.Figs.6and7showthecalculatedandmeasuredtemperaturesinthemiddleoftheeutecticAl–Sicastingoverthewatercooledsteelandcopperchills,respectively.Therightordinatesinthesefiguresindicatethetemperaturedifferencebetweenthecalculationandmeasurement.Inthecastingmid-point,thecalculatedandmeasuredtemperatureshaveoverlappedoverthesolidustime,andintheliquidustime,thetemperaturedifferencehasnotexceeded16Kand14Kwiththesteelandcopperchills,respectively.Figs.6and7demonstrateclearlythehighreliabilityandaccuracyofourcalculationsfordeterminationofthetimevaryingtemperaturefieldsinthechillandcasting.4.1.CoolingcurvesandheattransfercoefficientAfterthedeterminationofthetemperaturefield,theheattransferbetweenthecastingandchillhasbeencalculatedwiththehelpofEq.(2)andisshowninFig.8forthecopperandsteelchills.Then,theIHTChasbeenevaluatedwiththehelpofEq.(1).ThetimedependentvariationoftheIHTCisshowninFig.9,fromtheinitialmomentofthecastingprocessuntilaquasi-stationarysituationisreached,andcanbedistinguishedinmainlythreestages.4.1.1.FirststageLiquidispouredinthemold.Intheveryearly10–20s,asufficientlyhighliquidcolumnisnotyetformedsothatthisphaseshouldbecompletelyignored.Inthefirststage,whilethemetaliscompletelyliquidandhasperfectcontactwiththechillsurface,theheattransfercoefficientreachesitsmaximumvalueofabout19kW/m2Kforthecopperchilland6.5kW/m2Kforthesteelchill.OurcalculatedIHTCvaluesareverysimilartothoseintheliteratureforsolidifyingaluminumalloysincopperandsteelmolds[10,26,30,31].Noskinformationofsolidmetalonthechillsurfacewilloccurduetotheturbulencesduringthemoltenmetalpouringphaseintothemold.Whenpouringisstopped,theturbulencesdieout.Athinstableskinofsolidifiedmetalisformedonthechillbecausethechillextractsheatfromthemoltenmetal.Theinterfaceispressedagainstthechillbythehydrostaticpressureoftheliquidmetal.Then,theIHTCforthecopperchilldecreasedsharplyforashorttime.Thefirststagelastsonlyupto30sbecauseofthehighheatconductanceofthecopperchill.However,itlastsupto120sforthesteelchilloflowerheatconductance,inwhichtimetheIHTCdecreasedgraduallywithtime.Theeffectofhydrostaticpressuredecreaseswiththeincreasingofthesolidskinthickness.Inthefirststage,someparameters,suchasthewettabilityoftheliquidonthechillsurface,theamountofmeltsuperheat,surfaceroughness,moldtemperature,pouringmomentumofmelt,thermalconductivityofchill,hydrostaticpressureandturbulenceofmelt,affecttheheattransfercoefficient.4.1.2.SecondstageAfterformationofanadequatesolidmetalonthechillsurface,theperfectcontactbetweenthechillandthesolidifiedcastingnolongerexistsbecauseofcontractionofthesolidifiedcasting.Inaddition,thethermalconductivityoftheliquidismuchhigherthanthatofthesolid.However,thedecreasingoftheIHTConthecopperchillproceedscontinuouslyduetotheremainingintimatecontactanditshighconductivityuntilsolidificationiscompletedat135s.Fig.9showstheIHTConthesteelchillinthesecondstagetendedtoremainatconstantvalues,approximately6kW/m2Kduringsolidificationofthecasting,until310sbecausetheheatextractionratebythesteelchillisnotashighasthatofthecopperchillandthetemperaturedifferencesbetweenthesolidmetalandchillsurfaces(TC_TM)decreaseintime.ItcanbeseeninFigs.4and5forthesteelandcopperchills,respectively.Solidificationorientation,thermalconductivityandsurfaceroughnessofthechillarethemostimportantparametersoftheheattransfercoefficientinthisstage.4.1.3.ThirdstageAftersolidificationofthemetalinthemoldonthecopperchilliscompleted,theIHTCcontinuestodecreasetolowervaluesduetothehighconductivityofcopper.Ontheotherhand,theIHTConthesteelchillremainsatconstantvalues.Theeffectofthesolidifiedcastingcontractionmightbebalancedbythethermalexpansionofthesteelchillthatmightproducedaconstantcontactpressurebetweenthecastingandchillsurfaces.5.ConclusionsOurcalculatedresultshaveshownthattheappliedmodelfordeterminationofthemetalcasting–chillIHTCinonedimensionalheatflowisachievedsuccessfully,andthefollowingconclusionscanbesummarizedasfollows:1.AsatisfactoryFDMtoevaluatetheIHTCattheAl–Sieutecticmetalcastingatboththecopperandsteelchillinterfaceshasbeenachievedforonedimensionalheatflow.2.Thenumericalcalculatedandexperimentaltemperaturevalueshaveshownexcellentagreementand,consequently,ahighreliabilitygradefortheIHTC.3.TheIHTCvaluesduringtheverticallyupwardunidirectionalsolidificationofaeutecticAl–Sicastinghavevariedbetweenabout19–9.5kW/m2Kand6.5–5kW/m2Koncopperandsteelchills,respectively.Thesevalueshaveshowngoodagreementwiththoseintheliterature.4.Theresultshaveshownthattherecedingofthecastingfromboththecopperandsteelchillsurfacesdoesnotoccurduringthesolidification.5.TheIHTCcouldbeaffectedmainlybythecontactpositionandareabetweenthecastingandchillsurfacesroughness.Futureinvestigationshould,therefore,taketheseeffectsintoconsideration.外文资料翻译译文测定金属铸造–冷却接口的非稳态凝固的单向传热系数摘要在这项研究中，测量共晶铝硅垂直向上的界面换热系数（感应加热技术）是通过凝固过程中铸造水冷铜和水冷钢定向凝固完成的。有限差分方法（频分复用）是用于解决逆热传导问题（IHCP）。六计算机引导热电偶连接的冷却和铸造，和时间–温度数据的自动记录。热电偶被放置在位于对称5毫米，37.5毫米和75毫米的接口。如侧表面有很好的隔热，垂直向上的接口表面单向凝固过程的开始。测量的时间–温度数据文件所使用的有限差分法用一个明确的技术。热流量计算机程序已经写入估计过渡金属–冷感应加热技术在热传导反问题。实验和计算温度表现出极好的协调。该感应加热技术在垂直向上定向凝固铸造铝硅铜和钢–发冷有之间约19–9.5千瓦/平方米和6.5–5千瓦/平方米的变化。命名q热通量,W/m2热生成率每单位体积,W/m3h小时界面换热系数,W/m2KTC铸件表面温度,KTM模具温度（冷）表面,KT温度,Kt时间,sx距离,mk钾导热,W/mKC比热容量,J/kgKM编号l潜热,J/kgL长度,m，希腊符号q材料密度,kg/m3△t驱动时间间隔△x距离间隔下标m节点上标p时间表示1．简介金属冷界面传热，金属铸件凝固速度有其重要的影响力，研究了一些以往的试验研究。一些研究人员已经研究了传热机理铸件，找到影响因素的感应加热技术以及宏观传热值。在这些以往的研究中，该感应加热技术是依赖于许多因素的，包括存在和厚度的表面涂料，铸件表面的方向和大小铸件，冷或模具材料，应用压力，合金类型和组成，合金液的表面张力，模具和冷预热，合金过热度和冷表面粗糙度[1-11]。影响重力的方向有关的接口已审查通过调查与冷藏放置在底部，顶部或侧面模具[1]。为准确模拟凝固过程，它需要正确的边界条件应建立[12–14]。估计的传热系数在金属铸造–寒意接口通常是计算时间的–温度测量数据在凝固的单向冷冻实验铸造。铸造合金及冷材料用于实验铸造，一般，把一些材料和合金上准确地了解他们的物理行为是众所周知的，如铝，铜，铁和[15,16]。传热系数不同，取决于不同的实验条件和铸造合金[4]。回顾文献，可以发现，主要感应加热技术[17,18]有2种测定方法。一是衡量大小的差距之间形成金属铸造，冷和关联这一差距的大小与传热系数[19-21]。另一种方法是进行温度测量中的铸造和在寒冷的几个指定的地点和使用逆方法得出的感应加热技术[1,5,14]。一些研究人员已经研究了过渡金属–冷感应加热技术在定向凝固测量问题。这些研究表明，传热系数成为一个初始阶段凝固的高值，然后由于铸件的表面寒冷下降到一个低稳态值，形成一个界面差距[1,12,17,22,23]。由此发现，热传系数更高值时，凝固是垂直向上垂直向下或水平[1]。热损失，当金属首先接触到模具的调节不仅是蓄热能力的模具材料也由换热条件的金属本身，特别是在金属–冷却接口。山度士所确定的实体只有在接触孤立点，与实际接触面积只有一小部分的名义面积[12]。各种工艺参数及其影响的感应加热技术已审查了一些研究人员。在文献中，一些研究人员已经研究了确定感应加热技术在金属凝固冷却接口–铝合金铜，钢或铸铁模具和提供了一些广泛的不同价值观。这些值已报告高达20千瓦/平方米，小于1千瓦/平方米[35]–1,10,24钾。我们工作的目标是确定金属–冷感应加热技术在定向凝固垂直向上的一个圆柱形铝硅合金铸造–水冷铜的表面与钢冷和比较的感应加热技术的铜和钢发冷。在工作过程中，热流量计算机程序已经写入估计过渡金属–冷感应加热技术在热传导反问题。2．实验程序示意图的实验装置连接到数据记录器分析系统，铸造装置和位置的热电偶在定向凝固实验，如图1所示。在土耳其安卡拉的加齐大学，进行了2组实验来评价的感应加热技术进行液体合金（铝–硅）水冷钢和铜发冷技术。液体中铸造金属陶瓷模具由硅酸铝耐火管长度290毫米，内直径28毫米，壁厚10毫米。耐火管嵌入陶瓷棉20毫米厚度的横向热隔离的改进。圆柱冷（铜或钢）长度90毫米插入一个圆柱形模具如图1所示。热电偶是集中在共同的圆柱轴的寒冷和铸造在径向方向（见图1）。他们被置于对称和位于5毫米，37.5毫米和75毫米从铸造–冷却接口。所有热电偶是由电缆连接到一个数据记录仪与计算机接口。热物理性质的铸造和冷却材料选定为我们的实验总结于表1[36,37]。本实验用的–铝合金，共晶组成，有一个很窄的凝固范围。基准的目的，铜与低碳钢金属用于冷却体材料由于其众所周知的物理行为。垂直凝固装置的目的是提取只有通过水冷底板的允许热量。横向表面的很好的隔热，使单向凝固过程的开始垂直向上的接口表面。表1使用数据输入到计算机程序的感应加热技术热的物理性能[36,37]材料C,J/kgKq,kg/m3k,W/mK冷钢H13435.37+0.2·T7866.86-0.3174·T25冷铜351+0.11069·T9095.11-0.46292·T416.51-0.05874·TAl–%13Si(solid)11802682.54-0.2969·T149.2+0.019667·TAl–%13Si(liquid)12002613.27-0.2414·T0.865·T-648.75该合金熔化电阻炉熔化的金属合金，直到达到预定温度（980金），高于其熔点温度为849度，然后冷却到室温的模具。用于校准热电偶。六计算机引导热电偶连接的寒冷和铸造，和时间–温度数据自动记录。数据来自热电偶，在寒冷和铸造是用来绘制时间依赖性实验温度分布。测量的时间–温度数据文件被用来找到正确的边界条件以及相关的温度产生的频分复用使用一个明确的技术，这是纳入热流量计算机程序估计的过渡金属–冷感应加热技术，如在3章。流程图见图2概述了该解决方案的程序。3．传热系数的确定在我们的研究中，该感应加热技术在凝固过程的计算方法是解决热传导反问题用有限差分法。进行实验，以确定未知的温度和热通量之间的界面上的铸造和寒冷。时间–温度数据复制被用来评价边界条件。热通量的金属–寒意接口可以说是由一个宏观平均–冷金属感应加热技术（小时）。一个可以写作分母是平均热流在金属–冷界面瓦/平方米，与商标的计算界面温度的铸造金属表面和冷表面，分别。热通量为铸造冷却界面的计算从温度梯度的表面和次表面节点如下：是一个热传导材料冷铸造，W/mK，宏观平均感应加热技术（小时）计算公式（1）。3.1．传热系数的数学公式1．冷却的热流量有足够的绝缘的冷硬铸造室，热流量通过铸造可以合理近似为一一维传热问题。非稳态（瞬态）传导传热的一一维体可以被描述为T是温度，t是时间、x是笛卡尔坐标。是热扩散的导电材料，是一个热传导，是密度c是比热容量。是导电材料的热扩散率，k是热传导，是密度和c是比热容量。3.1.2概述铸造热运动铸件的热流量，控制方程类似于公式（3），但包含在左边（3）式。我们可以写传热方程凝固金属如下：；在左边，方程（5）是一个热源项，这是纳入考虑为凝固潜热，由；l是融合潜热，是固体部分的铸造。确定如下，（7）式：；在式（6）可以与温度表示如下：；式（8）代到（6）给出了方程，替代式（9）到（5）给出了方程，这个方程可以重新作为：；一个可以定义在凝固中作为一个明显的比热。然后，式（11）可以写为：图2.确定在金属铸造–冷却接口感应加热技术流程图。3.1.3概述有限差分法使用分析方法，在某些情况下，评估数学模型精确解稳定，一或二维导热问题。然而，这些解决方案是