最新制冷外文文献Word格式.docx

最新制冷外文文献Word格式.docx

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制冷外文文献

Keywords:

Steady-statesimulation、Semi-empiricalmodel、Domesticrefrigerators、Experimentalvalidation

1.Introduction

Ahouseholdrefrigeratoriscomposedofathermallyinsulatedcabinetandavapor-compressionrefrigerationloopasshowninFig.1.Theserefrigerationsystems,onthewhole,consumealargeamountofenergysincehundredsofmillionsarecurrentlyinuse,anddozensofmillionsarecomingontothemarketeveryyear.Anunderstandingoftheoperationalcharacteristicsofarefrigerationsystemisvitalforanyenergyoptimizationstudy,notonlytopredictitsperformance,butalsotoaidthedecisionmakingduringthedesignprocess.

Therefrigeratorperformanceisusuallyassessedbyoneofthefollowingapproaches:

（i）simplifiedcalculationsbasedoncomponentcharacteristics;

（ii）componentanalyzesthroughcommercialCFDpackages;

and（iii）standardizedexperiments.Althoughthefirsttwotechniquesplayimportantrolesincomponentdesign,theydonotprovideenoughinformationoncomponentmatchingandsystembehavior,whichisonlyobtainedbytestingtherefrigerator

inacontrolledenvironmentchamber.Thesetests,however,aretimeconsumingandexpensive.Afasterandlesscostlyalternativeistheuseofcomputermodelstosimulatethethermal-andfluid-dynamicbehaviorofrefrigerationsystems.

Manymathematicalmodelshavebeenproposedinthepastforrefrigeratormodeling.Inoneoftheearlieststudies,DavisandScott[1]developedamathematicalmodeltopredictthesteady-statecomponentbehavioroverarangeofoperatingconditions,consistingofindividualcomponentsub-modelsthatcombinedfirst-principleswithanumberofempiricalparametersobtainedfromtheliterature.Simplisticmodelswereusedforheatexchangersastheevaporatingandcondensingpressureswereassumedtobeknown.Thecompressormodel,ontheotherhand,consideredthein-cylindercompressionandthepressuredropsinthesuctionanddischargevalves.Nomodelhasbeenprovidedfortheexpansion

device.

Afewyearslater,theUnitedStatesDepartmentofEnergy（USDOE）sponsoredthedevelopmentofasteady-statesimulationmodelforhouseholdrefrigerators,whichwasintendedtobeadoptedasareferencetoestablishtheenergytargetsforAmericanhouseholdmanufacturers[2].BasedontheUSDOEmodel,severalincrementalstudieswerethencarriedout.First,Abramsonetal.

[3]incorporatedasub-modelforthecapillarytube-suctionlineheatexchanger,andthemodelwasadaptedtosimulateatwo-door‘Combi’refrigerator.Later,Reevesetal.[4]improvedtheoverallcomputationalperformanceusingthee-NTUmethodforheatexchangermodeling,andpolynomialfitsforthecompressormassflowrateandpowerconsumption.

Morerecently,Kleinetal.[5]proposedafirst-principlesmodelforsimulatingthesteady-statebehaviorofa230-lall-refrigerator,whichcomprisedthefollowingcomponentsub-models:

anaturaldraftwire-and-tubecondenser,aplate-type‘roll-bond’evaporator,acapillarytube-suctionlineheatexchanger,ahermeticreciprocatingcompressor,andaninsulatedcabinet.Themodelwasestablishedbasedonthemass,momentumandenergyconservationlaws,heattransferequations,equationsofstateoftheworkingmediaandempiricalcorrelationsderivedfromexperimentaldata.Thecapillarytube-suctionlineheatexchangersub-modelwasderivedfromamoresophisticatedmodel[6]throughafractionedfactorialdesigntechnique,whilstthecompressorsub-modelwasbasedoncurvefittingsofcalorimetricdata.

Inallofthestudiesmentionedabove,themodelsdependedonreliablecomponent-levelperformancedata,whichrequiredpurpose-builtexperimentalfacilitiesfortestingeachcomponent.Inthepresentstudy,therequiredempiricalinformationwasgathereddirectlybytestingtherefrigeratorinacontrolledtemperatureandhumiditychamber.Inordertodoso,therefrigerationsystemwasproperlyandcarefullyinstrumentedtominimizeanyaffectonitsperformance.Theconservationlawswereemployedtoestablishthegoverningequationsthatdescribethesystembehavior.Eachcomponentwasmodeledusingalumpedapproach,basedonphysicalprinciplesandemployingempiricalparameters（e.g.,heattransfercoefficientsandfrictionfactors）,adjustedtofittheexperimentaldata.Themodelshowedgoodagreementwithexperimentaldataduringthevalidationexercise.

2.Experimentalwork

Thetestswereperformedwitha430-ltop-mountfrost-freerefrigerator,assembledwithahermeticreciprocatingcompressor,anaturaldraftwire-and-tubecondenser,andatube-fin‘no-frost’evaporator.ThesealedsystememployedHFC-134aastheworkingfluid（130g）andsyntheticoilasthelubricant（250ml）.Theairtemperaturesinthefreezerandinthefresh-foodcompartmentswerecontrolledbyathermostatandbyathermostaticda