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1、第40卷第11期西安交通大学学报Vol.40112006年11月JOURNALOFXIANJIAOTONGUNIVERSITYNov.2006多孔介质中超临界压力CO2对流换热的实验研究石润富,姜培学,张宇(清华大学热能工程系热科学与动力工程教育部重点实验室,100084,北京)摘要:对超临界压力下CO2在颗粒直径为02~028mm的竖直烧结多孔介质圆管中的对流换热进行了实验研究.对热流密度、质量流量、入口压力及流动方向对对流换热规律的影响进行了研究,结果发现:准临界点附近CO2强烈的物性参数变化,尤其是定压比热的变化对对流换热的影响很大;
2、对流换热系数随着流体局部平均温度的升高在准临界点附近达到最大;随着热流密度的增加,对流换热系数出现先增大后减小的趋势;质量流量越大,对流换热越强;流动方向对对流换热的影响不大;随着压力靠近临界压力,CO2的物性参数变化越来越剧烈,对流换热系数在准临界点附近也越来越大,但随着流体温度远离准临界点,压力对对流换热的影响逐渐减小.关键词:对流换热;超临界压力;烧结多孔介质;实验研究中图分类号:TK124文献标识码:A文章编号:0253987X(2006)11125404ExperimentalInvestigationonConvectionHeatTransfer
3、ofSupercriticalCO2inPorousMediaShiRunfu,JiangPeixue,ZhangYu(KeyLaboratoryforThermalScienceandPowerEngineeringofMinistryofEducation,DepartmentofThermalEngineering,TsinghuaUniversity,Beijing100084,China)Abstract:ConvectionheattransferofCO2inaverticalsinteredporoustubewithparticlediameters
4、02028mmatsupercriticalpressureswasmeasuredexperimentally.Theeffectsofheatflux,massflowrate,inletpressure,andflowdirectionsonconvectionheattransferwereinvestigated.Theresultsshowthatthestrongvariationsofthermophysicalpropertiessignificantlyaffecttheconvectionheattransfer,especiallyth
5、esharpvariationofspecificheatatconstantpressurenearpseudocriticaltemperature.Convectionheattransfercoefficientshaveamaximumnearthepseudocriticaltemperaturewiththeincreaseoflocalfluidtemperature.Withtheincreaseofheatflux,convectionheattransfercoefficientsincreasetoamaximumandthendecrease
6、continuously.Convectionheattransferisenhancedwiththeincreaseofmassflowrate,buttheeffectofflowdirectionsonconvectionheattransferisnotsignificant.Theconvectionheattransfercoefficientsnearthepseudocriticaltemperatureincreasewiththeinletpressuredecreasingtothecriticalpressureduetotheincrea
7、sedvariationsofCO2thermophysicalproperties.However,theeffectofpressureonconvectionheattransferissmallatthefluidtemperaturefarfromthepseudocriticaltemperature.Keywords:convectionheattransfer;supercriticalpressure;sinteredporousmedia;experimentalinvestigation收稿日期:2006
