热能与动力工程专业英语基础词汇

1热能与动力工程专业英语词汇：基础部分Absoluteentropyisentropycalculatedrelativetotheabsolutereferencepointdeterminedbythethirdlawofthermodynamics.Absolutehumidity(specifichumidityorhumidityratio)isthemassofwatervaporpresentinaunitmassofdryair;thatis,itistheratioofthemassofwatervaportothemassofdryairinatmosphericair.Absolutepressureistheactualpressureatagivenpositionanditismeasuredrelativetoabsolutevacuum(i.e.,absolutezeropressure).Throughoutthistext,thepressurePwilldenoteabsolutepressureunlessspecifiedotherwise.AbsolutetemperaturesaretemperaturesmeasuredontheKelvinscaleorRankinescale,andthesetemperaturesvarybetweenzeroandinfinity.Absorptionchillersareair-conditioningsystemsbasedonabsorptionrefrigeration,andtheyperformbestwhentheheatsourcecansupplyheatatahightemperaturewithlittletemperaturedrop.Absorptionrefrigerationsystemsinvolvetheabsorptionofarefrigerantbyatransportmedium.Themostwidelyusedabsorptionrefrigerationsystemistheammonia–watersystem,whereammonia(NH3)servesastherefrigerantandwater(H2O)asthetransportmedium.Absorptionrefrigerationsystemsareeconomicallyattractivewhenthereisasourceofinexpensiveheatenergyatatemperatureof100to200°C.Someexamplesofinexpensiveheatenergysourcesincludegeothermalenergy,solarenergy,andwasteheatfromcogenerationorprocesssteamplants,andevennaturalgaswhenitisavailableatarelativelylowprice.Absorptivityisthefractionoftheradiationenergyincidentonasurfacethatisabsorbedbythesurface.Acidrainisdefinedasrainorsnowthatwashesacid-ladendropletsfromtheairontothesoil.Adiabaticcombustiontemperature(seeadiabaticflametemperature)Adiabaticflametemperatureisthemaximumtemperaturetheproductsofcombustionwillreachinthelimitingcaseofnoheatlosstothesurroundingsduringthecombustionprocess.Theadiabaticflametemperatureattainsitsmaximumvaluewhencompletecombustionoccurswiththetheoreticalamountofair.Adiabaticprocessisaprocessduringwhichthereisnoheattransfer.ThewordadiabaticcomesfromtheGreekwordadiabatos,whichmeansnottobepassed.2Adiabaticsaturationprocessistheprocessinwhichasteadystreamofunsaturatedairofunknownspecifichumidityispassedthroughalonginsulatedchannelthatcontainsapoolofwater.Astheairflowsoverthewater,somewaterwillevaporateandmixwiththeairstream.Themoisturecontentofairwillincreaseduringthisprocess,anditstemperaturewilldecrease,sincepartofthelatentheatofvaporizationofthewaterthatevaporateswillcomefromtheair.Ifthechannelislongenough,theairstreamwillexitassaturatedair(100percentrelativehumidity)attheexittemperature.Adiabaticsaturationtemperatureistheexittemperaturethatairattainsintheadiabaticsaturationprocess.Afterburnerisasectionaddedbetweentheturbineandthenozzleofanaircraftturbineenginewhereadditionalfuelisinjectedintotheoxygen-richcombustiongasesleavingtheturbine.Asaresultofthisaddedenergy,theexhaustgasesleaveatahighervelocity,providingextrathrustforshorttakeoffsorcombatconditions.Airconditionersarerefrigeratorswhoserefrigeratedspaceisaroomorabuildinginsteadofthefoodcompartment.Air–fuelratioAFisafrequentlyusedquantityintheanalysisofcombustionprocessestoquantifytheamountsoffuelandair.Itisusuallyexpressedonamassbasisandisdefinedastheratioofthemassofairtothemassoffuelforacombustionprocess.Air-sourceheatpumpsusethecoldoutsideairastheheatsourceinwinter.Air-standardassumptionsreducetheanalysisofgaspowercyclestoamanageablelevelbyutilizingthefollowingapproximations:1.Theworkingfluidisair,whichcontinuouslycirculatesinaclosedloopandalwaysbehavesasanidealgas.2.Alltheprocessesthatmakeupthecycleareinternallyreversible.3.Thecombustionprocessisreplacedbyaheat-additionprocessfromanexternalsource.4.Theexhaustprocessisreplacedbyaheatrejectionprocessthatrestorestheworkingfluidtoitsinitialstate.Air-standardcycleisacycleforwhichtheair-standardassumptionsareapplicable.Amagat’slawofadditivevolumesstatesthatthevolumeofagasmixtureisequaltothesumofthevolumeseachgaswouldoccupyifitexistedaloneatthemixturetemperatureandpressure.AnnualfuelutilizationefficiencyAFUEistheefficiencyofspaceheatingsystemsofresidentialandcommercialbuildingswhichaccountsforthecombustionefficiencyaswellasotherlossessuchasheatlossestounheatedareasandstart-upandcool-downlosses.3Apparentgasconstantofamixtureistheuniversalgasconstantdividedbytheapparentmolarmassofthemixture.Apparentmolarmassofamixturecanbeexpressedasthesumoftheproductsofthemolefractionandmolarmassofeachcomponentinthemixture.Atmosphericairistheairintheatmosphere,whichnormallycontainssomewatervapor(ormoisture).Autoignitionistheprematureignitionofthefuelthatproducesanaudiblenoise,whichiscalledengineknock.Averagegasconstant(seeapparentgasconstant)Averagemolarmass(seeapparentmolarmass)Averagevelocityistheaveragevalueofthenormalvelocityacrossanentireflowcrosssectionandifthevelocityweretheaveragevelocityallthroughthecrosssection,themassflowratewouldbeidenticaltothatobtainedbyintegratingtheactualvelocityprofile.Backpressureisthepressureappliedatthenozzledischargeregion.Backworkratioistheratioofthecompressorworktotheturbineworkingas-turbinepowerplants.Baristheunitofpressureequalto105pascal.Barometerisadevicethatmeasures