Latent heat - Wikipedia

Latent heat is energy released or absorbed, by a body or a thermodynamic system, ... Examples are latent heat of fusion and latent heat of vaporization ... Latentheat FromWikipedia,thefreeencyclopedia Jumptonavigation Jumptosearch Thermodynamicphasetransitionenergy ThermodynamicsTheclassicalCarnotheatengine Branches Classical Statistical Chemical Quantumthermodynamics Equilibrium /Non-equilibrium Laws Zeroth First Second Third Systems Closedsystem Opensystem Isolatedsystem State Equationofstate Idealgas Realgas Stateofmatter Phase(matter) Equilibrium Controlvolume Instruments Processes Isobaric Isochoric Isothermal Adiabatic Isentropic Isenthalpic Quasistatic Polytropic Freeexpansion Reversibility Irreversibility Endoreversibility Cycles Heatengines Heatpumps Thermalefficiency SystempropertiesNote:Conjugatevariablesinitalics Propertydiagrams Intensiveandextensiveproperties Processfunctions Work Heat Functionsofstate Temperature /Entropy (introduction) Pressure /Volume Chemicalpotential /Particlenumber Vaporquality Reducedproperties Materialproperties Propertydatabases Specificheatcapacity  c = {\displaystylec=} T {\displaystyleT} ∂ S {\displaystyle\partialS} N {\displaystyleN} ∂ T {\displaystyle\partialT} Compressibility  β = − {\displaystyle\beta=-} 1 {\displaystyle1} ∂ V {\displaystyle\partialV} V {\displaystyleV} ∂ p {\displaystyle\partialp} Thermalexpansion  α = {\displaystyle\alpha=} 1 {\displaystyle1} ∂ V {\displaystyle\partialV} V {\displaystyleV} ∂ T {\displaystyle\partialT} Equations Carnot'stheorem Clausiustheorem Fundamentalrelation Idealgaslaw Maxwellrelations Onsagerreciprocalrelations Bridgman'sequations Tableofthermodynamicequations Potentials Freeenergy Freeentropy Internalenergy U ( S , V ) {\displaystyleU(S,V)} Enthalpy H ( S , p ) = U + p V {\displaystyleH(S,p)=U+pV} Helmholtzfreeenergy A ( T , V ) = U − T S {\displaystyleA(T,V)=U-TS} Gibbsfreeenergy G ( T , p ) = H − T S {\displaystyleG(T,p)=H-TS} HistoryCulture History General Entropy Gaslaws "Perpetualmotion"machines Philosophy Entropyandtime Entropyandlife Brownianratchet Maxwell'sdemon Heatdeathparadox Loschmidt'sparadox Synergetics Theories Calorictheory Visviva("livingforce") Mechanicalequivalentofheat Motivepower Keypublications AnExperimentalEnquiryConcerning...Heat OntheEquilibriumofHeterogeneousSubstances ReflectionsontheMotivePowerofFire Timelines Thermodynamics Heatengines ArtEducation Maxwell'sthermodynamicsurface Entropyasenergydispersal Scientists Bernoulli Boltzmann Bridgman Carathéodory Carnot Clapeyron Clausius deDonder Duhem Gibbs vonHelmholtz Joule Lewis Massieu Maxwell vonMayer Nernst Onsager Planck Rankine Smeaton Stahl Tait Thompson Thomson vanderWaals Waterston Other Nucleation Self-assembly Self-organization Orderanddisorder Categoryvte Latentheat(alsoknownaslatentenergyorheatoftransformation)isenergyreleasedorabsorbed,byabodyorathermodynamicsystem,duringaconstant-temperatureprocess—usuallyafirst-orderphasetransition. Latentheatcanbeunderstoodasenergyinhiddenformwhichissuppliedorextractedtochangethestateofasubstancewithoutchangingitstemperature.Examplesarelatentheatoffusionandlatentheatofvaporizationinvolvedinphasechanges,i.e.asubstancecondensingorvaporizingataspecifiedtemperatureandpressure.[1][2] Thetermwasintroducedaround1762byScottishchemistJosephBlack.ItisderivedfromtheLatinlatere(toliehidden).Blackusedtheterminthecontextofcalorimetrywhereaheattransfercausedavolumechangeinabodywhileitstemperaturewasconstant. Incontrasttolatentheat,sensibleheatisenergytransferredasheat,witharesultanttemperaturechangeinabody. Contents 1Usage 1.1Meteorology 2History 3Specificlatentheat 4Tableofspecificlatentheats 5Specificlatentheatforcondensationofwaterinclouds 6Variationwithtemperature(orpressure) 7Seealso 8References Usage[edit] Graphoftemperatureofphasesofwaterheatedfrom−100 °Cto200 °C–thedashedlineexampleshowsthatmeltingandheating1 kgoficeat−50 °Ctowaterat40 °Cneeds600kJ Theterms″sensibleheat″and″latentheat″refertoenergytransferredbetweenabodyanditssurroundings,definedbytheoccurrenceornon-occurrenceoftemperaturechange;theydependonthepropertiesofthebody.″Sensibleheat″is″sensed″orfeltinaprocessasachangeinthebody'stemperature.″Latentheat″isenergytransferredinaprocesswithoutchangeofthebody'stemperature,forexample,inaphasechange(solid/liquid/gas). Bothsensibleandlatentheatsareobservedinmanyprocessesoftransferofenergyinnature.Latentheatisassociatedwiththechangeofphaseofatmosphericoroceanwater,vaporization,condensation,freezingormelting,whereassensibleheatisenergytransferredthatisevidentinchangeofthetemperatureoftheatmosphereorocean,orice,withoutthosephasechanges,thoughitisassociatedwithchangesofpressureandvolume. Theoriginalusageoftheterm,asintroducedbyBlack,wasappliedtosystemsthatwereintentionallyheldatconstanttemperature.Suchusagereferredtolatentheatofexpansionandseveralotherrelatedlatentheats.Theselatentheatsaredefinedindependentlyoftheconceptualframeworkofthermodynamics.[3] Whenabodyisheatedatconstanttemperaturebythermalradiationinamicrowavefieldforexample,itmayexpandbyanamountdescribedbyitslatentheatwithrespecttovolumeorlatentheatofexpansion,orincreaseitspressurebyanamountdescribedbyitslatentheatwithrespecttopressure.[4] Latentheatisenergyreleasedorabsorbed,byabodyorathermodynamicsystem,duringaconstant-temperatureprocess. Twocommonformsoflatentheatarelatentheatoffusion(melting)andlatentheatofvaporization(boiling).Thesenamesdescribethedirectionofenergyflowwhenchangingfromonephasetothenext:fromsolidtoliquid,andliquidtogas. Inbothcasesthechangeisendothermic,meaningthatthesystemabsorbsenergy. Forexample,whenwaterevaporates,energyisrequiredforthewatermoleculestoovercometheforcesofattractionbetweenthem,thetransitionfromwatertovaporrequiresaninputofenergy. Ifthevaporthencondensestoaliquidonasurface,thenthevapor'slatentenergyabsorbedduringevaporationisreleasedastheliquid'ssensibleheatontothesurface. Thelargevalueoftheenthalpyofcondensationofwatervaporisthereasonthatsteamisafarmoreeffectiveheatingmediumthanboilingwater,andismorehazardous. Meteorology[edit] Inmeteorology,latentheatfluxisthefluxofenergyfromtheEarth'ssurfacetotheatmospherethatisassociatedwithevaporationortranspirationofwateratthesurfaceandsubsequentcondensationofwatervaporinthetroposphere.ItisanimportantcomponentofEarth'ssurfaceenergybudget.LatentheatfluxhasbeencommonlymeasuredwiththeBowenratiotechnique,ormorerecentlysincethemid-1900sbytheeddycovariancemethod. History[edit] TheEnglishwordlatentcomesfromLatinlatēns,meaninglyinghidden.[5][6]Thetermlatentheatwasintroducedintocalorimetryaround1750byJosephBlack—commissionedbyproducersofScotchwhiskyinsearchofidealquantitiesoffuelandwaterfortheirdistillingprocess—tostudyingsystemchanges,suchasofvolumeandpressure,whenthethermodynamicsystemwasheldatconstanttemperatureinathermalbath.Blackwouldcomparethechangeintemperatureoftwoidenticalquantitiesofwater,heatedbyidenticalmeans,oneofwhichwas,say,meltedfromice,whereastheotherwasheatedfrommerelycoldliquidstate.Bycomparingtheresultingtemperatures,hecouldconcludethat,forinstance,thetemperatureofthesamplemeltedfromicewas140°Flowerthantheothersample,thusmeltingtheiceabsorbed140"degreesofheat"thatcouldnotbemeasuredbythethermometer,yetneededtobesupplied,thusitwas"latent"(hidden).Blackalsodeducedthatasmuchlatentheataswassuppliedintoboilingthedistillate(thusgivingthequantityoffuelneeded)alsohadtobeabsorbedtocondenseitagain(thusgivingthecoolingwaterrequired).[7] Later,JamesPrescottJoulecharacterisedlatentenergyastheenergyofinteractioninagivenconfigurationofparticles,i.e.aformofpotentialenergy,andthesensibleheatasanenergythatwasindicatedbythethermometer,[8]relatingthelattertothermalenergy. Specificlatentheat[edit] Aspecificlatentheat(L)expressestheamountofenergyintheformofheat(Q)requiredtocompletelyeffectaphasechangeofaunitofmass(m),usually1kg,ofasubstanceasanintensiveproperty: L = Q m . {\displaystyleL={\frac{Q}{m}}.} Intensivepropertiesarematerialcharacteristicsandarenotdependentonthesizeorextentofthesample.Commonlyquotedandtabulatedintheliteraturearethespecificlatentheatoffusionandthespecificlatentheatofvaporizationformanysubstances. Fromthisdefinition,thelatentheatforagivenmassofasubstanceiscalculatedby Q = m L {\displaystyleQ={m}{L}} where: Qistheamountofenergyreleasedorabsorbedduringthechangeofphaseofthesubstance(inkJorinBTU), misthemassofthesubstance(inkgorinlb),and Listhespecificlatentheatforaparticularsubstance(kJkg−1orinBTUlb−1),eitherLfforfusion,orLvforvaporization. Tableofspecificlatentheats[edit] Thefollowingtableshowsthespecificlatentheatsandchangeofphasetemperatures(atstandardpressure)ofsomecommonfluidsandgases.[citationneeded] Substance SLHoffusion(kJ/kg) Meltingpoint(°C) SLHofvaporization(kJ/kg) Boilingpoint(°C) Ethylalcohol 108 −114 855 78.3 Ammonia 332.17 −77.74 1369 −33.34 Carbondioxide 184 −78 574 Helium     21 −268.93 Hydrogen(2) 58 −259 455 −253 Lead[9] 23.0 327.5 871 1750 Methane 59 −182.6 511 −161.6 Nitrogen 25.7 −210 200 −196 Oxygen 13.9 −219 213 −183 RefrigerantR134a   −101 215.9 −26.6 RefrigerantR152a   −116 326.5 -25 Silicon[10] 1790 1414 12800 3265 Toluene 72.1 −93 351 110.6 Turpentine     293   Water 334 0 2264.705 100 Specificlatentheatforcondensationofwaterinclouds[edit] Thespecificlatentheatofcondensationofwaterinthetemperaturerangefrom−25 °Cto40 °Cisapproximatedbythefollowingempiricalcubicfunction: L water ( T ) ≈ ( 2500.8 − 2.36 T + 0.0016 T 2 − 0.00006 T 3 )   J/g , {\displaystyleL_{\text{water}}(T)\approx\left(2500.8-2.36T+0.0016T^{2}-0.00006T^{3}\right)~{\text{J/g}},} [11] wherethetemperature T {\displaystyleT} istakentobethenumericalvaluein°C. Forsublimationanddepositionfromandintoice,thespecificlatentheatisalmostconstantinthetemperaturerangefrom−40 °Cto0 °Candcanbeapproximatedbythefollowingempiricalquadraticfunction: L ice ( T ) ≈ ( 2834.1 − 0.29 T − 0.004 T 2 )   J/g . {\displaystyleL_{\text{ice}}(T)\approx\left(2834.1-0.29T-0.004T^{2}\right)~{\text{J/g}}.} [11] Variationwithtemperature(orpressure)[edit] Temperature-dependencyoftheheatsofvaporizationforwater,methanol,benzene,andacetone. Asthetemperature(orpressure)risestothecriticalpoint,thelatentheatofvaporizationfallstozero. Seealso[edit] Bowenratio Eddycovarianceflux(eddycorrelation,eddyflux) Sublimation(physics) Specificheatcapacity Enthalpyoffusion Enthalpyofvaporization References[edit] ^Perrot,Pierre(1998).AtoZofThermodynamics.OxfordUniversityPress.ISBN 0-19-856552-6. ^Clark,JohnO.E.(2004).TheEssentialDictionaryofScience.Barnes&NobleBooks.ISBN 0-7607-4616-8. ^Bryan,G.H.(1907).Thermodynamics.AnIntroductoryTreatisedealingmainlywithFirstPrinciplesandtheirDirectApplications,B.G.Tuebner,Leipzig,pages9,20–22. ^Maxwell,J.C.(1872).TheoryofHeat,thirdedition,Longmans,Green,andCo.,London,page73. ^Harper,Douglas."latent".OnlineEtymologyDictionary. ^Lewis,CharltonT.(1890).AnElementaryLatinDictionary.Entryforlatens. ^JamesBurke(1979)."CreditWhereIt'sDue".TheDaytheUniverseChanged.Episode6.Eventoccursat50(34minutes).BBC. ^J.P.Joule(1884),TheScientificPaperofJamesPrescottJoule,ThePhysicalSocietyofLondon,p. 274,Iaminclinedtobelievethatbothofthesehypotheseswillbefoundtoholdgood,—thatinsomeinstances,particularlyinthecaseofsensibleheat,orsuchasisindicatedbythethermometer,heatwillbefoundtoconsistinthelivingforceoftheparticlesofthebodiesinwhichitisinduced;whilstinothers,particularlyinthecaseoflatentheat,thephenomenaareproducedbytheseparationofparticlefromparticle,soastocausethemtoattractoneanotherthroughagreaterspace.,LectureonMatter,LivingForce,andHeat.May5and12,1847 ^Yaws,CarlL.(2011).Yaws'HandbookofPropertiesoftheChemicalElements.Knovel. ^Elert,Glenn(2021)."LatentHeat".ThePhysicsHypertextbook. ^abPolynomialcurvefitstoTable2.1.R.R.Rogers;M.K.Yau(1989).AShortCourseinCloudPhysics(3rd ed.).PergamonPress.p. 16.ISBN 0-7506-3215-1. vteStatesofmatter(list)State Solid Liquid Gas/Vapor Plasma Lowenergy Bose–Einsteincondensate Fermioniccondensate Degeneratematter QuantumHall Rydbergmatter Rydbergpolaron Strangematter Superfluid Supersolid Photonicmolecule Highenergy QCDmatter LatticeQCD Quark–gluonplasma Color-glasscondensate Supercriticalfluid Otherstates Colloid Glass Crystal Liquidcrystal Timecrystal Quantumspinliquid Exoticmatter Programmablematter Darkmatter Antimatter Magneticallyordered Antiferromagnet Ferrimagnet Ferromagnet String-netliquid Superglass Transitions Boiling Boilingpoint Condensation Criticalline Criticalpoint Crystallization Deposition Evaporation Flashevaporation Freezing Chemicalionization Ionization Lambdapoint Melting Meltingpoint Recombination Regelation Saturatedfluid Sublimation Supercooling Triplepoint Vaporization Vitrification Quantities Enthalpyoffusion Enthalpyofsublimation Enthalpyofvaporization Latentheat Latentinternalenergy Trouton'srule Volatility Concepts Baryonicmatter Binodal Compressedfluid Coolingcurve Equationofstate Leidenfrosteffect Macroscopicquantumphenomena Mpembaeffect Orderanddisorder(physics) Spinodal Superconductivity Superheatedvapor Superheating Thermo-dielectriceffect vteHeating,ventilation,andairconditioningFundamentalconcepts Airchangesperhour Bake-out Buildingenvelope Convection Dilution Domesticenergyconsumption Enthalpy Fluiddynamics Gascompressor Heatpumpandrefrigerationcycle Heattransfer Humidity Infiltration Latentheat Noisecontrol Outgassing Particulates Psychrometrics Sensibleheat Stackeffect Thermalcomfort Thermaldestratification Thermalmass Thermodynamics Vapourpressureofwater Technology Absorptionrefrigerator Airbarrier Airconditioning Antifreeze Automobileairconditioning Autonomousbuilding Buildinginsulationmaterials Centralheating Centralsolarheating Chilledbeam Chilledwater Constantairvolume(CAV) Coolant Crossventilation Dedicatedoutdoorairsystem(DOAS) Deepwatersourcecooling Demandcontrolledventilation(DCV) Displacementventilation Districtcooling Districtheating Electricheating Energyrecoveryventilation(ERV) Firestop Forced-air Forced-airgas Freecooling Heatrecoveryventilation(HRV) Hybridheat Hydronics Icestorageairconditioning Kitchenventilation Mixed-modeventilation Microgeneration Passivecooling Passivehouse Passiveventilation Radiantheatingandcooling Radiantcooling Radiantheating Radonmitigation Refrigeration Renewableheat Roomairdistribution Solarairheat Solarcombisystem Solarcooling Solarheating Thermalinsulation Underfloorairdistribution Underfloorheating Vaporbarrier Vapor-compressionrefrigeration(VCRS) Variableairvolume(VAV) Variablerefrigerantflow(VRF) Ventilation Components Airconditionerinverter Airdoor Airfilter Airhandler Airionizer Air-mixingplenum Airpurifier Airsourceheatpump Atticfan Automaticbalancingvalve Backboiler Barrierpipe Blastdamper Boiler Centrifugalfan Ceramicheater Chiller Condensatepump Condenser Condensingboiler Convectionheater Compressor Coolingtower Damper Dehumidifier Duct Economizer Electrostaticprecipitator Evaporativecooler Evaporator Exhausthood Expansiontank Fan Fancoilunit Fanfilterunit Fanheater Firedamper Fireplace Fireplaceinsert Freezestat Flue Freon Fumehood Furnace Gascompressor Gasheater Gasolineheater Greaseduct Grille Ground-coupledheatexchanger Groundsourceheatpump Heatexchanger Heatpipe Heatpump Heatingfilm Heatingsystem HEPA Highefficiencyglandlesscirculatingpump High-pressurecut-offswitch Humidifier Infraredheater Invertercompressor Keroseneheater Louver Mechanicalroom Oilheater Packagedterminalairconditioner Plenumspace Pressurisationductwork Processductwork Radiator Radiatorreflector Recuperator Refrigerant Register Reversingvalve Run-aroundcoil Scrollcompressor Solarchimney Solar-assistedheatpump Spaceheater Smokeexhaustductwork Thermalexpansionvalve Thermalwheel Thermosiphon Thermostaticradiatorvalve Tricklevent Trombewall Turningvanes Ultra-lowparticulateair(ULPA) Whole-housefan Windcatcher Wood-burningstove Measurementandcontrol Airflowmeter Aquastat BACnet Blowerdoor Buildingautomation Carbondioxidesensor Cleanairdeliveryrate(CADR) Gasdetector Homeenergymonitor Humidistat HVACcontrolsystem Intelligentbuildings LonWorks Minimumefficiencyreportingvalue(MERV) OpenTherm Programmablecommunicatingthermostat Programmablethermostat Psychrometrics Roomtemperature Smartthermostat Thermostat Thermostaticradiatorvalve Professions,trades,andservices Architecturalacoustics Architecturalengineering Architecturaltechnologist Buildingservicesengineering Buildinginformationmodeling(BIM) Deepenergyretrofit Ductleakagetesting Environmentalengineering Hydronicbalancing Kitchenexhaustcleaning Mechanicalengineering Mechanical,electrical,andplumbing Moldgrowth,assessment,andremediation Refrigerantreclamation Testing,adjusting,balancing Industryorganizations AHRI AMCA ASHRAE ASTMInternational BRE BSRIA CIBSE InstituteofRefrigeration IIR LEED SMACNA Healthandsafety Indoorairquality(IAQ) Passivesmoking Sickbuildingsyndrome(SBS) Volatileorganiccompound(VOC) Seealso ASHRAEHandbook Buildingscience Fireproofing GlossaryofHVACterms WorldRefrigerationDay Template:Homeautomation Template:Solarenergy Authoritycontrol:Nationallibraries Germany CzechRepublic Retrievedfrom"https://en.wikipedia.org/w/index.php?title=Latent_heat&oldid=1085689107" Categories:ThermochemistryAtmosphericthermodynamicsThermodynamicsPhysicalphenomenaHiddencategories:ArticleswithshortdescriptionShortdescriptionisdifferentfromWikidataAllarticleswithunsourcedstatementsArticleswithunsourcedstatementsfromJune2012ArticleswithGNDidentifiersArticleswithNKCidentifiers Navigationmenu Personaltools NotloggedinTalkContributionsCreateaccountLogin Namespaces ArticleTalk English Views ReadEditViewhistory More Search Navigation MainpageContentsCurrenteventsRandomarticleAboutWikipediaContactusDonate Contribute HelpLearntoeditCommunityportalRecentchangesUploadfile Tools WhatlinkshereRelatedchangesUploadfileSpecialpagesPermanentlinkPageinformationCitethispageWikidataitem Print/export DownloadasPDFPrintableversion Languages العربيةবাংলাBân-lâm-gúБългарскиCatalàČeštinaDeutschEestiEspañolEsperantoEuskaraفارسیFrançaisGaeilgeGalego한국어हिन्दीHrvatskiIdoBahasaIndonesiaItalianoעבריתJawaKreyòlayisyenLombardമലയാളംBahasaMelayuမြန်မာဘာသာNederlands日本語NorskbokmålNorsknynorskPolskiPortuguêsRomânăРусскийSimpleEnglishSlovenčinaکوردیСрпски/srpskiSrpskohrvatski/српскохрватскиSuomiSvenskaதமிழ்ไทยTürkçeУкраїнськаTiếngViệt粵語中文 Editlinks