结霜工况下翅片管换热器传热传质的数值模拟

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1、上海交通大学硕士学位论文结霜工况下翅片管换热器传热传质的数值模拟姓名：刘小川申请学位级别：硕士专业：制冷与低温工程指导教师：谷波20070101逐步增大，出口温度和含湿量变化平缓。在实验研究的基础上，得到了湿空气的压力分布和含湿量分布。将模拟所得结果与实验数据进行了对比，结果表明，模拟结果与实验数据变化趋势相同，模拟结果与实验数据吻合较好。本文所建立的翅片管换热器结霜模型得到了一个很好的模拟结果，此模型为国内翅片管换热器结霜模拟和其他设备、部件的结霜模拟介绍了一个全新的方法，为同类的结霜模型搭建了一个良好的平台。模型加深了我们对翅片管换热器干工况、结露工况和结霜

2、工况的理解，也加深了我们对如何模拟这些工况的认识。但模型仍有不足，还需要改进。关键词：翅片管式换热器结霜模拟VINumericalsimulationonheatandmasstransferoffrostformationonfinnedtubeheatexchangerABSTRACTFinnedtubeheatexchangersareextensivelyemployedinvariousindustrialapplications.Theyarequitecompact,lightlyweight,andcharacterizedbyarelative

3、lylowcostfabrication.Acomprehensiveunderstandingontheperformanceofheatandmasstransferoffinnedtubeheatexchangersisofprimeimportancetooptimizethedesignofheatexchangersforrefrigerationandairconditioningapplications.Frostformationonfinnedtubeheatexchangeroccurswidely.Whenmoistaircomesinc

4、ontactwithcoldheatexchangersurfacewhosetemperatureisbelowfreezingpoint,frostingoccurs.Thevaporoftheairbecomesfrostandthefroststickstothesurfaceoftheheatexchanger.Thefrostactsnotonlyasathermalinsulatorbetweenthesurfaceandthehumidambientair,butalsosignificantlyreducestheperformanceofth

5、eheatexchanger,sincetheairpassagesbecomenarrowerandpressuredropgeneratedbecomeshigher.Withtimegoesby,thethicknessofthefrostlayergrows.Inaddition,inordertoensurethedefrostingperiodoffinnedtubeheatexchanger,itisnecessarytounderstandthecharacteristicsoffrostformationdeeply.Asmallunitoff

6、innedtubeheatexchangerisstudied.Fromthesimulationresultsofthemodelofsmallunit,thesimulationperformanceofwholefinnedtubeheatexchangercanbeknown.Thecontinuous,momentum,energyandgridupdatingequationsoffrostformationonfinnedtubeheatexchangerweredescribed.。Usingnumericalmethod,thefrostacc

7、umulationquantityandheattransfercapacityofevaporatorsarepredicted,whichissimplifiedtoaquasi-stableproblemforconvenience.IneverytimesteptheprocessisconsideredtobestableandtheobtainedVIIdata,thefrostthicknessandthetemperatureofthefrostsurfaceareusedastheboundaryconditionsinthenexttimes

8、tep.Accordin