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翻译英文.pdf

翻译英文.pdf

上传者: lichunrui1988 2010-03-25 评分 0 0 0 0 0 0 暂无简介 简介 举报

简介:本文档为《翻译英文pdf》,可适用于外语资料领域,主题内容包含IEEETRANSACTIONSONENERGYCONVERSION,VOL,NO,JUNEHarnessingHighAltitudeSolarP符等。

IEEETRANSACTIONSONENERGYCONVERSION,VOL,NO,JUNEHarnessingHighAltitudeSolarPowerGuglielmoSAglietti,StefanoRedi,AdrianRTatnall,andThomasMarkvart,Member,IEEEAbstractAsanintermediatesolutionbetweenGlaser’ssatellitesolarpower(SSP)andgroundbasedphotovoltaic(PV)panels,thispaperexaminesthecollectionofsolarenergyusingahighaltitudeaerostaticplatformAproceduretocalculatetheirradianceinthemediumhightroposphere,basedonexperimentaldata,isdescribedTheresultsshowthathereaPVsystemcouldcollectaboutfourtosixtimestheenergycollectedbyatypicalUKbasedgroundinstallation,andbetweenonethirdandhalfofthetotalenergythesamesystemwouldcollectifsupportedbyageostationarysatellite(SSP)TheconceptoftheaerostatforsolarpowergenerationisthenbrieflydescribedtogetherwiththeequationsthatlinkitsmainengineeringparametersvariablesApreliminarysizingofafacilitystationedatkmaltitudeanditscosting,basedonrealisticvaluesoftheinputengineeringparameters,isthenpresentedIndexTermsEnergyconversion,photovoltaic(PV)powersystems,PVspacepowersystems,powerconversion,solarenergy,solarpowersatellites,solarradiation,terrestrialatmosphereNOMENCLATUREAcondCrosssectionalareaoftheconductorAMRELRelativeairmassBAerostatbuoyancyCdAerostatdragcoefficientDAerostatdragforcehLengthofverticalsegmentoflightbeampathdz,zLengthofinclinedsegmentoflightbeampatheSolarelevationangleEBTotalbeamirradiationgGravityacceleration(ms)hAltitudeHLocalhourangleILightbeamintensityILightbeamintensitybeforeenteringtheatmospherepRELRelativepressurePgenPowergeneratedbythePVsystemrAlResistivityofthealuminumRRadiusoftheballoonSOveralllengthoftheconductorSTLengthofthetetherTTensioninthetethervWindvelocityVVoltageManuscriptreceivedJune,revisedJuly,CurrentversionpublishedMay,PapernoTECTheauthorsarewiththeSchoolofEngineeringSciences,UniversityofSouthampton,SouthamptonSOBJ,UK(email:gsasotonacuk)Colorversionsofoneormoreofthefiguresinthispaperareavailableonlineathttp:ieeexploreieeeorgDigitalObjectIdentifierTECVolVolumeoftheaerostatWaeroWeightofaerostatincludingPVdevicesWcond,Wfib,WtetherWeightofconductor,reinforcingfibers,andtotalweightofthetetherαExtinctionparameterδSundeclinationδaero,δcellsAreadensityoftheenvelopematerialandPVcellsδcond,δfibDensityofconductorandtetherreinforcingfibersγFractionoftheenvelopesurfacecoveredbyPVcellsηEfficiencyθzSolarZenithangleρair,ρgasDensitiesofairandgasfillingtheaerostatσuTetherreinforcingfibersstrengthϕGeographicallatitudeΦSolarfluxIINTRODUCTIONTHEDEVELOPMENTofnewandcosteffectivemethodstoharnessrenewableenergyhasbecomecrucialtomaintaintheenergysupplythatunderpinsoursociety,andsolarpowerisoneofthemaincandidatestomakeasubstantialcontributiontofulfilourfutureenergyrequirementsOneofthemajorissuesintheuseofgroundbasedphotovoltaic(PV)panelstoharvestsolarpoweristherelativelylowenergydensitythatiscompoundedbythefactthatthepoweroutputofthedevicesisstronglydependentonthelatitudeandweatherconditionsThesefactorshaveparticularlyhinderedthediffusionofPVinseveralcountrieswithcloudyclimates(eg,northEuropeancountries)Ontheotherhand,areaswithhighsolarirradiations(eg,Africandesertssee)areremotefrommostusersandthelossesoverthousandsofmilesofcablesandthepoliticalissuesentailedinsuchalargeproject,severelyreducetheeconomicadvantagesAcompletelydifferentapproachwasproposedbyGlaserinthes,andhisideahascapturedtheimaginationofscientistsuptothisdayThebasicconceptwastocollectsolarenergyusingalargesatellite(whichwouldbeabletocapturethefullstrengthofthesolarradiationcontinuously),andtransmitittothegroundusingmicrowaveradiationThereceivingstationwouldthenconvertthemicrowaveradiationintoelectricenergytobemadeavailabletotheusersTheoriginalconceptwasrevisitedininviewoftheconsiderabletechnologicaladvancesmadesincethes,andresearchworkonthisconceptisstillongoingHowever,amixtureoftechnicalissues(suchasthelossesintheenergyconversionsandtransmission),safetyconcerns(regardingthemicrowavebeamlinkingthesatellitewiththegroundstation),andcost,havedeniedthe$IEEEAuthorizedlicenseduselimitedto:SHANGDONGUNIVERSITYDownloadedonJanuary,at:fromIEEEXploreRestrictionsapplyAGLIETTIetal:HARNESSINGHIGHALTITUDESOLARPOWERpracticalimplementationofthisconceptThelatterisasubstantialhurdleasthedevelopmentofsatellitesolarpower(SSP)cannotbecarriedoutincrementally,inordertorecoverpartoftheinitialcostduringthedevelopment,anduseittofundthefollowingsteps,butitrequiressubstantialfundingupfront(tensofbillionsofdollarsaccordingto)beforethereisanyeconomicalreturnAsacompromisebetweenGlaser’sSSPandgroundbasedPVdevices,itisproposedinthispapertocollectthesolarenergyusingahighaltitudeaerostaticplatform,Thisapproachallowsmostoftheissuesrelatedtotheweatherconditiontobeovercome,astheplatformwillbeabovethecloudsexceptforveryextremeweathersituationsAtthesametime,astheplatformisabovethedensestpartofthetroposphere,thesunbeamwilltravelthroughconsiderablylessairmassthanifitwasontheground(inparticular,forearlymorningandevening),andthiswillfurtherimprovetheenergyoutputTherefore,thismethodenablesconsiderablymoresolarpowertobecollectedthanontheground(inthispaper,itwillbeshownthatataltitudesabovekm,itispossibletocollectoverfourtimesmoreenergythanusingpanelsfixedonthegroundintheUK)Inaddition,themooringlineoftheplatformcanbeusedtotransmittheelectricenergytothegroundinrelativesafetyandwithlowelectricallossesAlthoughthisapproachenablesbetweenonethirdandhalfoftheenergythatcouldbeharvestedusinganSSP,thecostoftheinfrastructureisordersofmagnitudelower,andthisapproachallowsanincrementaldevelopmentwithacosttofirstpower,ie,afewordersofmagnitudessmallerthanthatnecessaryforSSPMostresearchersuptillnowhaveproposedharvestingenergyathighaltitudebyexploitingthestrongwindsexistinginthehighatmospherebyusingflyingelectricalgenerators(FEG),thatareessentiallywindturbinescollectingwindpowerataltitudesfromafewhundredmeterstokmormorealtitude(toexploitthepowerfuljetstreamcurrents)Theextractionofthisenergyusingthetypeofmachinesproposed,forexample,byRobertsin,althoughfeasibleandmostprobablyeconomicallyviable,isrelativelycomplexinmechanicaltermsOneoftheissuesisthatinlowwind,themachine(whichisheavierthanair)needstoreverseitsenergyflowandtakeenergyfromthegroundtoproduceenoughlifttosupportitselfandthetetherAlternativedesignsliketheMAGENNinovercomethisproblemusingalighterthanairapproachsothatthebuoyancykeepsitinflightallthetimeHoweverthemechanicalcomplicationsarestillconsiderableTheexploitationofsolarenergyathighaltitudemaythereforebesimplerinengineeringmechanicalterms,andprovideaverypredictablereliablesourceOneofthecrucialstepstodemonstratetheviabilityoftheconceptisareliablecalculationofthesolarenergyavailableasafunctionofthealtitude,andthisisthesubjectofthefirstsectionofthispaperTheconceptoftheaerostatforsolarpowergeneration(ASPG)isthendescribedtogetherwiththeequationsthatlinkitsmainengineeringparametersvariables,andapreliminarysizingofanASPG,basedontherealisticvaluesoftheinputengineeringparametersispresentedFinally,asectiononcostingshowshowthisconceptcouldprovideaviablemethodtoharvestsolarenergyandtotransformitintoelectricityforgroundusersIISOLARIRRADIANCEVARIATIONWITHALTITUDESolarradiationtravelingthroughtheatmosphereisattenuatedbytwomainkindsofprocessesThefirstprocessisdefinedasscatteringanditinvolvestheairmolecules(Rayleighscattering)andthelargerparticlesthatcanchangethedirectionofthephotonsafteraninteraction(Miescattering)Theothermainprocessisthemolecularabsorption,inwhichtheenergyofthephotonsisconvertedintosomeotherformsInboththeseprocesses,energyisremovedfromthebeamoflightThetotalattenuationofthelight,travelingthroughameanisknownasextinctionInthecaseoftheEarth’satmosphere,mostoftheattenuationisduetoscatteringAsaresultoftheseprocesses,theglobalsolarradiationfallingonasurfacecanbedividedintotwomaincomponents:direct(orbeam)anddiffuseForlowanglesofincidenceofthesunbeamandoracloudysky,thebeamcomponentcanbeverylowsothatmostoftheenergycaptured(global)isactuallythediffusedcomponentBothscatteringandabsorptionstronglydependontheatmosphericcharacteristicsthatthesunbeamfindsalongitspathfromspacetothegroundAsaconsequence,itisimportanttodefinethesepropertiesatvariousaltitudesabovethegroundHowever,inpractice,mostofthepublisheddataareconcernedwiththeevaluationoftheintensityoftheradiation(irradiance)atthegroundlevel,whereasforthisapplication,itisnecessarytoassesstheirradianceatthealtitudewheretheaerostatisduetooperateToachievethisobjective,mathematicalmodelsdescribingtheattenuationofthesunbeamtravelingtoEarthinclearskyconditionscanbeintegratedwithrealdatadescribingthefurtherattenuationproducedbythepresenceofclouds,toobtainareliableassessmentoftheirradianceataspecificaltitudeThemathematicalprocedureisdescribedinthenextsections,andtherealdatasetincludingtheeffectofthecloudsatvariousaltitudeswasprovidedbytheCloudnetProjectThedatacontainextinctionparameters(ie,theparameterdescribingthesunbeamattenuation)obtainedfromRadarLidarmeasurementsatChilboltonObservatory,UKAAtmosphericExtinctionModelingTheattenuationofabeamoflighttravelingthroughtheEarth’satmosphereisdefinedasatmosphericextinction,andcanbequantitativelydescribedbytheextinctionparameterαConsideringalightbeamofintensityIgoingthroughalengthdzofatmospherecharacterizedbyanextinctionα,thelossofintensityduetotheattenuationprocess,canbeexpressedwiththefollowingdifferential:dII=αdz()InthecaseoftheEarth’satmosphere,thepathlengthfromthetopoftheatmospheretotheground,canbedividedinsegmentsofconstantextinctionαiandlengthdziTherefore,()canberewrittentoestimatetheintensityofthebeamthatreachestheAuthorizedlicenseduselimitedto:SHANGDONGUNIVERSITYDownloadedonJanuary,at:fromIEEEXploreRestrictionsapplyIEEETRANSACTIONSONENERGYCONVERSION,VOL,NO,JUNEFigSolarZenithandbeampathrelationforgroundlevelandaltitudeh(a)Beampathstogroundlevel(b)BeampathstothealtitudehgroundasI=Ieαizi()whereIistheirradiancebeforethebeamenterstheatmosphereandthesumconsidersallthesegmentscrossedbythelightbeamWithreferencetoFig(a),toevaluatethepathlengthintheEarthatmosphere,animportantparameteristherelativeAirMassAMRELThisparameterdefinestheratiobetweentheairmasscrossedbyalightbeam(atanyangleθz),andthatcrossedwhenthesunisattheZenith,Therefore,thiscanalsobetakenastheratiobetweenthesegmentzandthesegmenth,crossinganatmosphericlayerofthicknesshiandcharacterizedbyaconstantextinctionαiTherefore,itispossibletowritethatzi=AMREL(ϑZ)hi()whereforsmallanglesθzAMREL(ϑZ)=cos(ϑZ)()whileforlargervaluesofθz,Youngdevelopedthefollowingrelation,()asshownatthebottomofthispageThesolarZenithangleθzcanbecomputed,fromthetime(dayoftheyearandhouroftheday)andthelocation(latitudeandlongitude)asdescribedinThesolarelevationangleiscalculatedase=Arcsin(sinϕsinδcosϕcosδcosH)()whereϕistheobservergeographicallatitude,δisthesundeclination,andHisthelocalhourangleThesolarelevationangleisthenrelatedtothesolarZenithasϑZ=e()Theseequationscanbebacksubstitutedin()toobtainI(h,ϑZ)=IeAMREL(ϑZ)αizi()Thesumin()shouldincludealltheintervalsinwhichαiissignificant,andhereonlythefirstkmofatmosphereisconsidered,beyondwhichtheextinctionparameterbecomesforourpurposenegligible,andtheintensityoftheradiation(I)isassumedconstantandequaltoWmThesunbeamenteringtheEarth’satmosphereencountersinitiallyaclearatmosphere,ascloudsareusuallyonlyinthelowestfewkilometersTherefore,theinitialstageofthecomputationistoconsideraclearatmosphere(nextsection),andthen,belowacertainaltitudetheextinctionparameterismodifiedtoconsidertheinfluenceandfilteringeffectoftheclouds)ExtinctionforClearAtmosphere:Theextinctiondata(αi)inclearskyconditionsareprovidedbyEltermanandusing()itispossibletoworkoutthevalueofthebeamirradianceatvariousaltitudesinclearskyAlternatively,itispossibletosimplify(),consideringthetotalextinctionproducedcrossingthewholeairmassoftheatmosphereαINT=(αihi)()andratherthancalculatingαINTfromthesummationoftheextinctionparametersthroughthewholeatmosphere(describedbytheαiseries),αINTcanbecalculatedstartingfromthestandardtestconditions,whichareusedtoevaluatetheperformanceofcommercialPVsystemsIntheseconditions,apanelisilluminatedwithanintensityofWmatatemperatureofCwitharelativeairmassofTheWmaretheglobalradiation,ie,directbeamcomponentplusdiffusedradiation,andbeamcomponentisaroundoftheglobal,reachingavalueofaboutWm,Withthesevalues,andI=WmthevalueofαINTcanbeobtained(αINT=)Therefore,()canberewrittenasI(ϑZ)=IeAMREL(ϑZ)αINT()anditcanbeusedtodeterminetheirradiancethatreachestheground,dependingonthevalueoftherelativeairmass(andthesolarZenithangle)Inordertobeabletocalculatethebeamirradianceatanaltitudeh,asshowninFig(b),()hastobemodifiedtoconsiderthefactthatonlyaportionoftheairmassisabovethealtitudehAsafirstapproximationthisportioncanbeassumedasproportionaltotheratiobetweenthepressureatthealtitudehandpressureatgroundlevel(ie,totherelativepressureath)Therefore,usingthedescriptionofthestandardtropospherepREL(h)=(php)=(ThT)()whereT=K(C)Thistermcanbeincludedin()togivethebeamirradianceinclearskyatanyaltitudehI(h,ϑZ)=IepREL(h)AMREL(ϑZ)αINT()AMREL(ϑZ)=cos(ϑZ)cos(ϑZ)cos(ϑZ)cos(ϑZ)cos(ϑZ)()Authorizedlicenseduselimitedto:SHANGDONGUNIVERSITYDownloadedonJanuary,at:fromIEEEXploreRestrictionsapplyAGLIETTIetal:HARNESSINGHIGHALTITUDESOLARPOWERFigMonthlyvariationofthetotalextinctionαINTobtainedfromgrounddataTheresultsobtainedusingthisequation,areindeedveryclosetothoseobtainedusing()Finally,toimprovecorrelationwiththedatafromgroundobservation,thevalueofαINTin()canbemodifiedtoincludeitsvariationduringthevariousmonthsoftheyearThedatasettocalculatethemonthlyvaluesofαINTwereprovidedbyphotovoltaicgeographicalinformationsystem(PVGIS)ThenewvaluesofαINTareshowninFig,andtheycanbeusedin()tocalculatethebeamirradianceforthevariousmonthsSofarthecalculationsreflectclearskyconditions,andiftheaerostatwasstationed“always”abovetheclouds(sayatkm),theseequationswouldbesufficienttocalculatethebeamirradianceHowever,practicalreasons(eg,tolimitinterferencewithinternationalairtraffic)mayrequirethattheaerostatbestationedataloweraltitude(km),andhereattimes(althoughnotveryoften),thereisthepossibilityofcloudsobscuringthesunTherefore,valuesofextinctionfortheactualatmosphere(includingclouds)havetobeused,asshowninthenextsection)ActualAtmosphereExtinction:ThedatasetsuppliedbytheCloudnetprojectcontainstheextinctionparametersfromthemeasurementsacquiredatChilboltonObservatory,UKFigshowsanexampleofthedataobtained,describingtheextinctionparameterduringthemonthofMayThedataareobtainedfromRadarLidarmeasurementsataltitudesbetweenandkmTheobservationswereperformedalmosteverydayoftheyear(fromApriltoSeptember),hoursadayTheextinctiondatafromtheChilboltonobservatoryarethensubstitutedintothedatafortheclearatmosphere,asshowninFig,whichrepresentstheaverageforthemonthofMarchTheintegrationofthebeamirradianceduringtheday(fromsunrisetosunset),leadstothedeterminationofthetotalbeamenergy(beamirradiationEB)thatfallsonasurfacelocatedatdifferentaltitudesabovethesealevel(Fig),andsunpointingEB(h)=SSSRIB(h)dt()whereSSandSRindicatesunsetandsunriseFigshowsthebeamirradianceforandkmaltitude,comparedtotheirradiancefortypicalgroundbasedPVsystems,andSSPTheintegrationofthedataforthecaseofkmaltitudeisshowninTableI,whereitcanbeseenthatadirectbeamirradiationofaboutkWhmcanreachthisaltitudeBGlobalIrradiationandPVDeviceOutputEstimationInordertocalculatethetotalenergythatreachesthePVsurface(globalirradiation),thediffusedcomponentoftheirradiationhastobesummedtothebeamcomponentcalculatedintheprevioussectionThediffusedcomponentcanbeasignificantportionoftheglobalirradiation,especiallyconsideringagroundbasedPVsystemsunderovercastskyTheratiobetweendiffuseandglobalradiationthatreachesthegroundusuallyvariesfordifferentmonths,and,forexample,forSouthampton,thediffusedcomponentintotalisactuallymorethanhalfofthetotalradiation(dataprovidedbyPVGIS)Consideringclearatmosphereconditions,theratiobetweendiffuseandglobalradiationismuchlessandcanbeassumedtohaveavalueofabout,,whileforasatelliteinLEO(lowEarthorbit)itcanbeconsideredabout(here,theradiationisactuallydiffusedreflectedbytheEarth)Inordertoestimatethedif

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