吸热表面热辐射特性对太阳能腔式吸热器热效率的影响.pdf

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1、中国科技论文在线http://www.paper.edu.cn吸热表面热辐射特性对太阳能腔式吸热器#热效率的影响1222**屠楠，方嘉宾，魏进家，杜轩成5（1.西安工程大学电子信息学院，西安710048；2.西安交通大学化学工程与技术学院，西安710049）摘要：太阳能腔式吸热器是塔式热发电系统中实现将聚光后的高热流密度太阳能转换为工质高温热能的关键设备，其内部涉及到复杂的光热转换以及能量吸收传递的过程。本文以一个10典型结构的饱和水工质太阳能腔式吸热器作为研究对象，建立了具有选择性吸收特性表面的太阳能腔式吸热器热性能的耦合计算模型。利用该模型，数值研究了吸热器内部半灰吸热

2、面的热辐射特性对其热性能的影响。结果表明增大吸热面对太阳辐射的吸收率能显著提高吸热效率；与吸热面暴露在外部环境中的吸热器不同，吸热面自身的热发射率对腔式吸热器热效率的影响趋势取决于吸热面与闲置腔体壁面之间的宏观传热方向，并不单一地表现为热发射15率增大则热损失也增大以致热效率降低的规律。该研究可为高聚光比下的塔式太阳能热发电系统中腔式吸热器内部吸热面覆盖涂层的设计和选择提供理论依据。关键词：太阳能热发电；腔式吸热器；吸收率；发射率；热效率中图分类号：TM61520EffectofThermalRadiationCharacteristicsonThermalEfficien

3、cyofaSolarCavityReceiver1222TUNan,FANGJiabin,WEIJinjia,DUXuancheng(1.SchoolofElectronicsandInformation,Xi'anPolytechnicUniversity,Xi'an710048;2.SchoolofChemicalEngineeringandTechnology,Xi'anJiaotongUniversity,Xi'an710049)25Abstract:Solarcavityreceiverisakeycomponentinthesolartowerpowersyst

4、em,whichconvertssolarradiationenergyintothermalenergy.Thesolar-thermalconversionandheattransferprocessesinsidethereceiverareverycomplicated.Asaturatedwater/steamsolarcavityreceiverwithtypicalgeometrywaschosenastheresearchobjectinthispaper.Acouplingmodelwasestablishedforcalculatingthetherma

5、lperformanceofthereceiver.Theselectiveabsorptioncharacteristicsofinternal30surfacesinsidethereceiverwereconsidered.Bythiscalculationmodel,theeffectofthermalradiationcharacteristicsofsemi-grayabsorbersurfacesonthethermalperformanceofthereceiverwereinvestigated.Theresultsdemonstratedthatthet

6、hermalefficiencyofthereceivercanberemarkablyenhancedbyincreasingthesolarabsorptivity.Theinfluenceofthermalemissivityonthethermalefficiencyofthereceiverdependsontheinfraredheattransferdirectionatmacrolevelbetweenthe35absorbersurfacesandvacantcavitywalls,whichmeansthattheincreaseofthermalemi

7、ssivitymaynotnecessarilyleadtothedecreaseofthermalefficiency.Thisisdifferentfromtheotherreceiverswhoseabsorbersurfacesareexposedintheair.Thepresentworkcanprovidetheoreticalbasisforthedesignandselectionofcoatingsonabsorbersurfacesinsidethesolarcavityreceiver.Ke