太陽(yáng)能熱水器高聚光比聚光技術(shù)儲(chǔ)熱材料和換熱方式

太陽(yáng)能熱水器高聚光比聚光技術(shù)儲(chǔ)熱材料和換熱方式

太陽(yáng)能熱水器高聚光比聚光技術(shù)儲(chǔ)熱材料和換熱方式太陽(yáng)能熱水器高聚光比聚光技術(shù)儲(chǔ)熱材料和換熱方式1太陽(yáng)能熱發(fā)電的工作原理Workingprincipleof1solarthermalpowergeneration太陽(yáng)能熱發(fā)電是指利用聚光器將低密度的太陽(yáng)能匯聚到焦斑處，使其生成高密度的能量，然后由工作流體將其轉(zhuǎn)換成熱能，再利用熱能發(fā)電。目前，已經(jīng)達(dá)到商業(yè)化應(yīng)用水平的太陽(yáng)能熱發(fā)電方式主要有：塔式、槽式、碟式三種方式。Solarthermalpowergenerationreferstotheuseofcondenserlowdensitysolarconvergetothefocalpoint,theformationofhighdensityofenergy,andthenbytheworkingfluidisconvertedintoheatenergy,recyclingheatenergypowergeneration.Atpresent,thesolarthermalpowergenerationhasreachedcommercialapplicationlevelare:Tower,trough,disctypeinthreeways.1.1塔式太陽(yáng)能熱發(fā)電系統(tǒng)1.1towersolarthermalpowergenerationsystem塔式太陽(yáng)能熱發(fā)電系統(tǒng)將吸熱器（單側(cè)受光或四周受光）置于接收塔的頂部，若干臺(tái)定日鏡根據(jù)吸熱器的類型，排列在接收塔的一側(cè)或四周。這些定日鏡自動(dòng)跟蹤太陽(yáng)，使其反射光能夠精確地投射到吸熱器內(nèi)。吸熱器將太陽(yáng)光能轉(zhuǎn)變成熱能，并加熱盤(pán)管內(nèi)流動(dòng)著的介質(zhì)（水或其他流體）產(chǎn)生中高溫蒸汽（溫度可達(dá)5600C以上）驅(qū)動(dòng)汽輪發(fā)電機(jī)組發(fā)電。目前，塔式熱發(fā)電系統(tǒng)總效率13%左右，聚光—吸熱部分效率70%左右。研究表明，塔式熱發(fā)電系統(tǒng)具有聚光比和溫度高、熱傳遞路程短、熱損耗少、系統(tǒng)綜合效率高等特點(diǎn)，極適合于大規(guī)模、大容量（一般在30～400MW之間）商業(yè)化應(yīng)用。但其一次性投入較大，每臺(tái)定日鏡都需一個(gè)單獨(dú)的二維跟蹤機(jī)構(gòu)，裝置結(jié)構(gòu)和控制系統(tǒng)復(fù)雜，成本較高。Solarthermalpowertowersystemreceiver(unilaterallightorbyreceivinglight)onthetopofthetower,apluralityofheliostatbasedonthetypeofabsorber,arrangedinthereceivingside,oraroundthetower.Theheliostattoautomaticallytrackingthesun,sothatthereflectedlightcanbeaccuratelyprojectedtotheheatabsorberin.Heatconvertssolarenergyintoheatenergy,andtheheatingcoilinsidetheflowingmedium(waterorotherfluids)producedinhightemperaturesteam(abovethetemperatureupto5600C)drivethesteamturbinegenerator.Atpresent,thetowerthermalpowersystemtotalefficiencyofabout13%,about70%light-absorbingefficiency.Researchshowsthat,thetowerthermalpowergeneratingsystemwithconcentrationratioandhightemperature,heattransferinshortdistance,lowheatloss,comprehensivesystemefficiencyhighercharacteristic,verysuitableforlarge-scale,largecapacity(30～400MWingeneral)commercialapplication.Buttheone-timeinvestmentislarger,eachheliostatrequiresasingletwo-dimensionaltrackingmechanism,devicestructureandcontrolsystemofcomplex,highcost.1.2槽式太陽(yáng)能熱發(fā)電系統(tǒng)1.2parabolictroughsolarthermalpowergenerationsystem槽式太陽(yáng)能熱發(fā)電系統(tǒng)，采用向一個(gè)方向彎曲的拋物線形槽式反射鏡面將太陽(yáng)光聚焦到位于焦線的吸熱管上，使管內(nèi)的傳熱工質(zhì)（油或水）加熱至一定溫度，然后經(jīng)熱交換器產(chǎn)生蒸汽驅(qū)動(dòng)汽輪發(fā)電機(jī)組發(fā)電。聚光—吸熱裝置采用一維自動(dòng)跟蹤系統(tǒng)跟蹤太陽(yáng)的運(yùn)行。槽式熱發(fā)電系統(tǒng)結(jié)構(gòu)簡(jiǎn)單、成本較低，并可將多個(gè)聚光—吸熱裝置經(jīng)串、并聯(lián)排列，構(gòu)成較大容量的熱發(fā)電系統(tǒng)。但其聚熱比較小、熱傳遞回路長(zhǎng)，傳熱工質(zhì)溫度難以提高，系統(tǒng)綜合效率較低。Troughsolarthermalpowergenerationsystem,usingparabolictroughreflectorcurvatureinonedirectionfocussunlighttoheatinthefocallinepipe,theheattransferfluidinsidethetube(oilorwater)isheatedtoacertaintemperature,thenthroughtheheatexchangertoproducesteamtodriveasteamturbinegeneratorset.Condenser-automatictrackingsystemtotrackthesun'sbasedonaone-dimensionalheatabsorbingdevice.Troughsolarpowersystemhastheadvantagesofsimplestructure,lowcost,andcanbeapluralityofcondensingheatabsorbingdevice,throughaseriesofparallelarrangement,consistingoflargecapacitythermalpowergenerationsystem.Buttheheatisrelativelysmall,theheattransferlooplength,heattransferfluidtemperatureisdifficulttoimprovethecomprehensiveefficiencyofthesystem,lower.1.3碟式太陽(yáng)能熱發(fā)電系統(tǒng)The1.3dishsolarthermalpowersystem碟式太陽(yáng)能熱發(fā)電系統(tǒng)，是利用旋轉(zhuǎn)拋物面反射鏡，將入射陽(yáng)光聚集在鏡面焦點(diǎn)處，而在該處可放置太陽(yáng)能吸熱器吸收太陽(yáng)能并加熱工質(zhì)驅(qū)動(dòng)汽輪發(fā)電機(jī)組發(fā)電。碟式熱發(fā)電系統(tǒng)采用二維跟蹤使得聚光鏡面始終正對(duì)太陽(yáng)，故其聚光效率最高。碟式熱發(fā)電系統(tǒng)可單機(jī)標(biāo)準(zhǔn)化生產(chǎn)，具有使用壽命長(zhǎng)、綜合效率高、運(yùn)行靈活性強(qiáng)等特點(diǎn)，可以單機(jī)使用或多臺(tái)并聯(lián)使用，非常適合邊遠(yuǎn)山區(qū)離網(wǎng)分布式發(fā)電。Dishsolarthermalpowersystem,istheuseoftheparaboloidalreflector,theincidentsunlightonthemirrorfocus,wherecanbeplacedsolarabsorberabsorbssolarenergyandheatingmediumdriveturbinepowergeneration.Disktypethermalpowergenerationsystemusing2Dtrackingthecondensermirroralwaysfacingthesun,sotheconcentrationefficiencyisthehighest.Disktypethermalpowergenerationsystemcanbesinglestandardizedproduction,hastheadvantagesoflongservicelife,highcomprehensiveefficiency,operationflexibility,canusesingleormultipleparalleluse,verysuitableforremoteareasawayfromthenetworkofdistributedgeneration.2太陽(yáng)能熱發(fā)電需要解決的關(guān)鍵技術(shù)問(wèn)題Thekeytechnicalproblemsneedtobesolvedinthe2solarthermalpowergeneration太陽(yáng)能熱發(fā)電技術(shù)由系統(tǒng)設(shè)計(jì)技術(shù)、光學(xué)技術(shù)、熱學(xué)技術(shù)、材料技術(shù)、電氣技術(shù)等組成。下面分別對(duì)各部分中的一些關(guān)鍵問(wèn)題進(jìn)行分析。Solarthermalpowergenerationtechnologybysystemdesigntechnology,opticaltechnology,thermaltechnology,materialstechnology,electricaltechnologyetc..Thefollowinganalysisisconductedonsomekeyissuesineachpartofthe.2.1系統(tǒng)設(shè)計(jì)技術(shù)2.1systemdesigntechnology太陽(yáng)能熱發(fā)電系統(tǒng)優(yōu)化設(shè)計(jì)的基點(diǎn)在于建立準(zhǔn)確的太陽(yáng)能熱電站的“聚光—吸熱—傳熱—儲(chǔ)熱—發(fā)電”過(guò)程的動(dòng)態(tài)熱力學(xué)模型，并進(jìn)行多工況的模擬分析。研究太陽(yáng)能熱發(fā)電“光—熱—電”系統(tǒng)在啟動(dòng)、正常運(yùn)行、待機(jī)、停機(jī)和事故等多種正常和非正常工況下的性能，系統(tǒng)內(nèi)各單元的相應(yīng)動(dòng)作以及對(duì)發(fā)電的影響。找到某種氣象條件下電價(jià)成本最優(yōu)的系統(tǒng)組成方案。Solarthermalpowersystemoptimizationdesignbasedondynamicthermodynamicmodeltoestablishaccuratesolarthermalpowerstation"spotlight-heat-transfer-heatstorageandpower"process,simulationanalysisandmultiplecondition.Studyofsolarthermalpowergeneration"light-heat-electricity"systematthestart,normaloperation,shutdown,standbyandaccidentandsoonmanykindsofnormalandabnormalconditionperformance,thecorrespondingactionofeachunitinthesystemandtheeffectonthegenerationof.Findthesystemcostoptimalschemecomposedsomemeteorologicalconditions.2.2光學(xué)問(wèn)題The2.2opticalproblems（1）高效率低成本塔式聚光場(chǎng)設(shè)計(jì)。(1)withhighefficiencyandlowcosttowerconcentratordesign.在大型塔式太陽(yáng)能熱發(fā)電系統(tǒng)中，聚光場(chǎng)的年光學(xué)效率很大程度上決定了電站的年總發(fā)電量，聚光場(chǎng)的成本占電站總成本的50%，因此研究設(shè)計(jì)高效率低成本定日鏡場(chǎng)具有重要意義。對(duì)于定日鏡的光學(xué)設(shè)計(jì)，需要考慮太陽(yáng)光譜特性、大角度入射的像差特性及太陽(yáng)發(fā)散角的影響，以及定日鏡的位置、塔高、地形、吸熱器的接收角等。Inthelarge-scalesolarthermalpowertowersystem,condenserfieldopticalefficiencylargelydeterminesthetotalannualoutputfromthepowerstations,concentrationfieldofthetotalcostat50%,sothedesignofhighefficiencyandlowcostoftheheliostatfieldhasimportantsignificance.Fortheopticaldesignofheliostat,itneedstoconsidertheimpactofaberrationandthesun,thesolarspectrumcharacteristicofthedivergenceoflargeangleofincidenceangle,andthepositionofaheliostat,tower,terrain,theheatreceivingangle.（2）輕型高強(qiáng)度槽式聚光反射面。(2)highintensitylighttroughconcentratingreflector.采用盡量輕的反射材料和支撐結(jié)構(gòu)是降低槽式聚光器成本和自身能耗的重要措施。直接采用曲面玻璃鏡作為反射面的槽式聚光技術(shù)是這一代技術(shù)的代表。Usedasalightreflectingmaterialandsupportingstructureisanimportantmeasuretoreducethetroughconcentratorcostanditsenergyconsumption.Directuseofcurvedglassmirrorasthereflectingsurfacetroughconcentratingtechnologyisrepresentativeofthisgenerationtechnology.（3）高聚光比聚光技術(shù)。(3)highconcentratingratiocondensingtechnology.主要包括二次反射聚光、塔頂反射聚光、輪胎面聚光和分束聚光等技術(shù)。Includingtworeflectiveconcentrator,thereflectingcondenser,condenserandthebeamspottiresurfacetechnology.（4）光學(xué)選擇性涂層。(4)opticalselectivecoating.它是對(duì)太陽(yáng)輻射具有光學(xué)選擇性的涂層，是各種高效吸熱器的基礎(chǔ)，具有高溫化學(xué)穩(wěn)定性。Itistheradiationcoatingwithopticalselectivetothesun,isthebasisofallkindsofefficientheatabsorbingdevice,hashighchemicalstability.2.3熱學(xué)問(wèn)題2.3thermalproblems（1）吸熱器低熱損機(jī)理。(1)theheatabsorberheatlossmechanism.減少吸熱器的反射損失、熱發(fā)射損失和自然對(duì)流損失是提高吸熱器效率的關(guān)鍵。Toreducethereflectionloss,absorberandheatemissionlossandnaturalconvectionlossisthekeytoimprovetheheatefficiency.（2）吸熱器安全性及壽命。(2)theheatabsorbersafetyandlife.吸熱器長(zhǎng)期工作在高密度、變化的輻射熱流條件下，工作環(huán)境非常惡劣。又由于它是太陽(yáng)能熱發(fā)電的核心部件之一，吸熱器損壞必然造成電站停止運(yùn)行，所以，吸熱器的安全性非常重要。Radiationheatfluxheatabsorberworkinginhighdensity,changesovertime,theworkenvironmentisverypoor.Andbecauseitisoneofthecorecomponentsofsolarthermalpowergeneration,heatdamagewillinevitablyleadtopowerstationstostoprunning,sotheheatabsorber,safetyisveryimportant.（3）高溫傳熱工質(zhì)。(3)hightemperatureheattransferfluid.提高吸熱器工質(zhì)的沸點(diǎn)，降低其熔點(diǎn)是提高工質(zhì)性能的一個(gè)重要目標(biāo)，也是提高發(fā)電效率的重要手段。水和混合熔融鹽是目前最常用的傳熱儲(chǔ)熱工質(zhì)。Toimprovetheheatabsorberrefrigerantboilingpoint,lowerthemeltingpointisanimportanttargetforimprovingworkingperformance,andalsoanimportantmeanstoimprovetheefficiencyofpowergeneration.Waterandmixingofthemoltensaltisthemostcommonlyusedinheattransferofthermalmassstorage.（4）儲(chǔ)熱材料和換熱方式。(4)theheatstoragematerialandheatexchangemode.儲(chǔ)熱工質(zhì)的工作溫度范圍決定了太陽(yáng)能熱發(fā)電設(shè)備的入口參數(shù)。要解決的關(guān)鍵問(wèn)題包括儲(chǔ)熱材料\/換熱器耦合的一體化設(shè)計(jì)方法，提高儲(chǔ)熱材料的熱容、工作溫度和工質(zhì)的化學(xué)及物理穩(wěn)定性，工質(zhì)容器及輸運(yùn)管路的防腐等。Operatingtemperaturerangestoragethermaltransferdeterminestheentranceparametersofsolarthermalpowergenerationequipment.Keyissuestobeaddressedincludeintegrateddesignmethodofthermalstoragematerials&heatexchangercoupled,improvethephysicalandchemicalstabilityofthermalstoragematerialsheatcapacity,workingtemperatureandrefrigerant,refrigerantcontainerandanticorrosiontransportpipeline.2.4材料問(wèn)題2.4material太陽(yáng)能熱發(fā)電系統(tǒng)主要包括集熱、傳輸、蓄熱與熱交換以及發(fā)電等四個(gè)單元。每個(gè)單元都涉及大量的材料研究開(kāi)發(fā)和應(yīng)用問(wèn)題。材料性能的突破可能會(huì)帶來(lái)太陽(yáng)能熱發(fā)電效率的大幅度提高或成本大幅度下降。太陽(yáng)能熱發(fā)電過(guò)程中需解決的材料問(wèn)題主要有以下五類：Solarthermalpowergenerationsystemincludesheatcollection,transmission,storageandexchangeofheatandpowerandotherfourunits.Eachunitissuesrelatedtoresearchanddevelopmentandapplicationoflargeamountsofmaterial.Abigincreaseorcostgreatlymaterialpropertiesmaybringaboutabreakthroughinsolarthermalpowergenerationefficiency.Materialproblemsneededtobesolvedinsolarthermalpowergenerationprocessinthefollowingfivecategories:（1）太陽(yáng)光反射材料。(1)thesunlightreflectionmaterial.主要是以金屬、玻璃及高分子材料為基材的太陽(yáng)光反射材料的高反射率、材料反射表面防護(hù)技術(shù)、表面自潔凈技術(shù)、高精度曲面反射鏡等。Mainlyinmetal,glassandpolymermaterialforsolarlightreflectingmaterialsofhighreflectivity,reflectivematerialsurfaceprotectiontechnology,surfaceself-cleaningtechnology,highaccuracysurfacemirroretc..（2）光熱轉(zhuǎn)換材料。(2)aphotothermalconversionmaterial.主要是槽式聚光器用金屬（玻璃）真空管中的相關(guān)材料，以及耐高溫太陽(yáng)光譜選擇性涂層。Mainlytroughconcentratorwithmetal(glass)relatedmaterialsinthevacuumpipe,andhigh-temperaturesolarselectiveabsorptioncoating.（3）中高溫蓄熱材料。(3)inhightemperatureheatstoragematerial.無(wú)機(jī)蓄熱載體（如高性能水泥混凝土、耐熱纖維、隔熱保溫材料等）；中高溫相變和化學(xué)反應(yīng)蓄熱介質(zhì)；與蓄熱材料相匹配的蓄熱器結(jié)構(gòu)設(shè)計(jì)。Inorganicheatcarrier(suchasthehighperformancecementconcrete,heat-resistantfiberinsulationmaterials,etc.);phasechangeandchemicalreactioninhightemperatureheatstoragemedium;regeneratorstructuredesignedtomatchtheheatstoragematerial.（4）高溫?zé)崃總鬏斀橘|(zhì)。(4)hightemperatureheattransfermedium.高溫?zé)崃總鬏敳牧虾徒橘|(zhì)（水、鹽、空氣等）；高溫?zé)崃總鬏敼艿兰捌錈岱雷o(hù)材料。Hightemperatureheattransfermaterialandmedium(water,salt,air);hightemperatureheattransferpipeandheatprotectionmaterial.（5）熱電轉(zhuǎn)換材料。(5)thethermoelectricconversionmaterial.高效熱電轉(zhuǎn)換材料是利用溫差原理直接將熱能轉(zhuǎn)化成電能的新能源材料。Efficientthermoelectricconversionmaterialsistheuseoftemperaturedifferenceprincipledirectlyconvertthermalenergyintoelectricalenergynewenergymaterials.3太陽(yáng)能熱發(fā)電技術(shù)在中國(guó)的應(yīng)用前景Applicationprospectof3solarthermalpowergenerationtechnologyinChina從中國(guó)太陽(yáng)能分布情況看，西部和北部沙漠地區(qū)太陽(yáng)能直射資源非常豐富。從太陽(yáng)能熱發(fā)電的原理可以看出，其發(fā)電過(guò)程需要適量的水，發(fā)電站需建在有水源的地方。通過(guò)有關(guān)部門(mén)的考察調(diào)研，以下幾個(gè)地區(qū)適合建立大規(guī)模太陽(yáng)能熱發(fā)電站：FromthedistributionofsolarenergyinChina,solardirectresourcesinthewesternandnortherndesertregionisveryrich.Fromtheprincipleofsolarthermalpowergenerationcanbeseen,itsgenerationprocessrequirestherightamountofwaterpowerstationtobebuilt,inthewatersourceplace.Throughtheinvestigationandstudyofrelevantdepartments,suitableforbuildinglarge-scalesolarthermalpowerstationinthefollowingareas:3.1渾善達(dá)克沙地3.1theOtindagSandyLand分布于內(nèi)蒙古高原東部，包括內(nèi)蒙古錫林郭勒盟的南部和赤峰的西北部，總面積為2.14萬(wàn)km2。該地區(qū)太陽(yáng)能輻射資源較豐富，年累計(jì)輻射量為5573MJ\/m2。降水條件較好，有不少淡水湖泊分布，水資源條件良好。LocatedintheeasternInnerMongoliaplateau,includingInnerMongolia,southernXilinguoleMengandnorthwesternChifeng,atotalareaof21400km2.Solarradiationresourcesareabundantinthearea,thecumulativeamountofradiationfor5573MJ\/m2years.Precipitationconditionisgood,therearemanyfreshwaterlakewaterresourcesdistribution,goodcondition.3.2科爾沁沙地3