Slide 1OutlineEnergy Storage MaterialsHeat of FusionPhase Change ApplicationsPCM ApplicationsDesirable QualitiesDesirable QualitiesEncapsulationDifficulties with PCMPCM TypesOrganic PCMsOrganic PCMs (Paraffins)Organic PCMs (Fatty Acids)Salt Hydrates (Molten Salts)Inorganic PCMsInorganic PCMsInorganic MixturesEutectic SaltsTransition in Binary MixturesCommercial PCMsOperating TemperaturesApplication: Solar HeatingComparisonApplication: Solar RefrigerationApplication: Data StorageApplication: Heat PadHeat Transfer Modeling: Phase ChangeMoving Boundary ProblemsSolid-Liquid TransitionAnalytical Solutions in Phase Change ProblemsSolidification (One-Region Problem)Solidification (Two-Region Problem)Two-Region ProblemConvective EffectsNumerical Simulation in Phase Change ProblemsEnthalpy MethodDiscretizationAlgorithm (explicit scheme)Algorithm (implicit scheme)Equivalent Heat Capacity MethodTemperature-Transforming ModelMelting/Solidification with Natural ConvectionGoverning EquationsResultsPorous Media: Averaging Techniques for Multiphase TransportPorous Media : One-Region MeltingSolution: Porous Media : One-Region MeltingCorrelations: Liquid  Solid  VaporLiquid–Vapor TransitionDropwise and Film CondensationPhase Change ParametersWater-moving MaterialsMicrofluidic ChipsBoilingBoilingSlide 57Theoretical maximum heat fluxCorrelationsCorrelations: BoilingCorrelations: BoilingConjugate Conduction-Surface ConvectionCorrelation for Multiphase Flow SystemsCorrelations: CondensationCorrelations: Liquid  VaporSurface EvaporationJacob NumberJet SprayImpingement (no boiling)Impingement (with boiling)Correlations: Jet ImpingementMacro-scale analysisCombined micro and macro effectsCorrelation NumberCorrelationsResults (impacting jet)Effect on Heat TransferSingle and Multiple dropletsWall Spray ImpactionMicro-Scale AnalysisPart V- Q/AHeat Transfer Enhancement Using PCMHeat Transfer MaterialsStorage, Transport, and TransformationPart II: Phase ChangeA Short Course byReza Toossi, Ph.D., P.E.California State University, Long Beach1OutlinePhase Change MaterialsApplicationsPropertiesModelingMelting and SolidificationBoiling and CondensationEvaporationAerosol Jet Impingement2Energy Storage Materials3Abhat, A., “Low temperature latent heat thermal energy storage: heat energy storage materials,” Solar Energy, 30 (1983) 313-332.Heat of Fusion4Exothermic (warming processes)Condensation▪Steam radiatorsFreezing▪Orange growers spray oranges with iced waterDeposition▪Snowy days are warmer than clear days in the winterEndothermic (cooling processes)Evaporation/Boiling▪Sweat▪Alcohol is “cool”Melting▪Melting ice in drinksSublimation▪Cooling with dry iceMelting Point (oC)Latent Heat (kJ/kg)Density (kg/m3)Steel1400 247 7800Copper1086 206 8900Ice0 335 917Sodium Sulfate32 252 1495Phase Change ApplicationsSolid-LiquidTemperature control AblationCoatingLiquid-VaporEvaporative cooling5PCM ApplicationsEnergy Storage in BuildingsThermal Inertia and Thermal protectionPassive heating and coolingThermoelectric RefrigerationTransport of temperature sensitive materialsThermal ControlIndustrial Forming (casting, laser drilling)Food and Pharmaceutical ProcessingTelecom SheltersHuman-comfort footwear and clothesThermos and coolersElectrical GenerationCogenerationThermoelectric Power GenerationSecurity of Energy SupplyFlow-through heat exchangers Microencapsulated PCMs6Desirable QualitiesThermodynamic CriteriaA melting point at the desired operating temperatureA high latent heat of fusion per unit massA high densityA high specific heatA high thermal conductivityCongruent meltingSmall density differences between phasesLittle supercooling during freezing7Desirable QualitiesChemical CriteriaChemical stabilityNon-corrosive, non-flammable, non-toxicOthersLong shelf-lifeApplicabilityReliabilityCommercial availabilityLow cost8EncapsulationWithout encapsulation (container shape and material)EncapsulationBuilding materials (PCM 50-80%, unsaturated polyester matrix 45-10%, and water 5-10%)9Difficulties with PCMAvailability of small number of materials in the temperature range of interestUseful lifeMaintenanceStabilityWater loss10PCM TypesOrganic CompoundsParaffinsFatty AcidsSalt-Based CompoundsSalt HydratesEutecticsOthersIce and waterZeolite11Organic PCMsAdvantagesA wide range of melting pointsNon-toxic, non-corrosiveChemically stableCompatible with most building materialsHigh latent heat per unit massMelting congruityNegligible supercoolingAre available for wide range of temperaturesDisadvantagesExpensiveLow densityLow thermal conductivity (compared to inorganic compounds)Large coefficient of thermal expansionFlammableDo not have a well-defined melting temperatures.12Organic PCMs (Paraffins)13Organic PCMs (Fatty Acids)14Salt Hydrates (Molten Salts)AdvantagesLower costHigh latent heat per unit mass and volumeHigh thermal conductivityWide range of melting points (7-117oC)DisadvantagesHigh rate of water lossCorrosivePhase separationSubstantial SubcoolingPhase segregation (lack of thermal stability)15Inorganic PCMs16Inorganic PCMs17Inorganic Mixtures18Eutectic Salts19Transition in Binary Mixtures20Commercial PCMs21Operating TemperaturesCooling (5-15oC)Temper diurnal swingsHeat pumpsSolar hot-water heating systemsAbsorption air conditioner22Application: Solar Heating23RoofWallWindowVelraj, R. , and Pasupathy, A., “PHASE CHANGE MATERIAL BASED THERMAL STORAGE FOR ENERGY CONSERVATION IN BUILDING ARCHITECTURE “Institute for Energy Studies, CEG, Anna University, Chennai - 600 025. INDIA.Comparison24Based on 9 m2 of solar collector areaTES Systems Cost ($) Volume (m3)Water 54 0.72Rock 217 @ $8/ton 2.46Glauber’s Salt 146 0.18Application: Solar Refrigeration25Application: Data StorageConventional CD (read only)CD-R (recordable)CD-RW (read and write)26Application: Heat PadSodium acetate (trihydrate)Tsl = 54oC∆hsl = 1.86x105 J/kg27Heat Transfer Modeling: Phase ChangeMelting of SolidsSurface EvaporationBoilingFilm BoilingPool BoilingCondensationFilm CondensationDropwise CondensationAerosol Jet SprayNucleationImpingement28Moving Boundary