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1、HeatTransferEnhancementNanofluid1INTRODUCTIONNanofluid：Nanofluidisanewkindofheattransfermedium,whichdispersesmetalornon-metalnanopowderintowater,alcohol,oilandothertraditionalheattransfermedium,andmakesituniform,stableandhighlyconductive.Twopartsofnanofluid:Nanoparticles:metal,oxide
2、,carbide,nitride,carbonnanotubesandotherparticles.Liquidbase:water-solubleorwater-insolubleliquid,water,alcohol,oilandothermedia2MECHANISM(1)InteractionandCollisionParticle&particle,particles&liquid,particle&wall(2)LargeSpecificSurfaceHeattransferareabetweentheparticlesandthesuspens
3、ioniscorrespondinglylarger.(3)BrownianmotionNanoparticlesdisperseinliquidsufficiently(4)Largethermalconductivity(5)Particleconcentration3MATHMODEL2.1Thetraditionaltheoreticalformulaforthethermalconductivityofsolid-liquidmixtures2.2Anothermodeltocalculatethethermalconductivityofsolid
4、-liquidmixtureswithsphericalparticle2.3Measurementofthermalconductivityofnanofluidsbytransienthot-wiremethod(1)AnequilibriumtemperatureofT0thehotwire.(2)Aconstantheatflowqissuddenlyaddedtothehotwire.(3)ΔT(r,t)atrofthehotwire(5)Assumingr=r0,thesurfaceofthelineheatsourceandtheliquidha
5、vethesametemperatureT(r0,t),andr2/(4αt)isverysmall.3MATHMODEL(6)DifferentiatebothsidesC=exp(γ)k:thermalconductivityoftheliquidα:thermaldiffusioncoefficientoftheliquid,E1(x):exponentialintegral4APPLICATIONReference:Thefirstapplicationofmulti-walledcarbonnanotubesnanofluidsconcentrate
6、dsolarcollectorsinthelowersection.(ChinesescholarsQiyuanLi)Result:Thecondensertypesolarcollectorbasedonnanofluidcaneffectivelyobtainsolarradiationenergy,istoapplynanotechnologyinalowcost,lowefficiencyinthefieldofheatingcollectorConcentratedsolarcollector;(2)TEMimagesofplasma-functio
7、nalizedmulti-walledcarbonnanotubes;(3)Uv-visiblespectraofcarbonnanotubestreatedwithKPSinDILiQ,ZhengC,MesgariS,etal.Experimentalinvestigationofananofluidabsorberemployedinalow-profile,concentratedsolarthermalcollector[C]//Micro+NanoMaterials.MOREAPPLICATIONSNanofluidshavegreatpotenti
8、alapplicationsinthe
