纳米流体强化传热ppt-丁岩

HeatTransferEnhancementNanofluid1INTRODUCTIONNanofluid：Nanofluidisanewkindofheattransfermedium,whichdispersesmetalornon-metalnanopowderintowater,alcohol,oilandothertraditionalheattransfermedium,andmakesituniform,stableandhighlyconductive.Twopartsofnanofluid:Nanoparticles:metal,oxide,carbide,nitride,carbonnanotubesandotherparticles.Liquidbase:water-solubleorwater-insolubleliquid,water,alcohol,oilandothermedia2MECHANISM(1)InteractionandCollisionParticle&particle,particles&liquid,particle&wall(2)LargeSpecificSurfaceHeattransferareabetweentheparticlesandthesuspensioniscorrespondinglylarger.(3)BrownianmotionNanoparticlesdisperseinliquidsufficiently(4)Largethermalconductivity(5)Particleconcentration3MATHMODEL2.1Thetraditionaltheoreticalformulaforthethermalconductivityofsolid-liquidmixtures2.2Anothermodeltocalculatethethermalconductivityofsolid-liquidmixtureswithsphericalparticleppffeffpfk(dT/dx)k(1)(dT/dx)K(dT/dx)(1)(dT/dx)pffpefffpffpk2k2(kk)Kkk2k(kk)2.3Measurementofthermalconductivityofnanofluidsbytransienthot-wiremethod(1)AnequilibriumtemperatureofT0thehotwire.(2)Aconstantheatflowqissuddenlyaddedtothehotwire.(3)ΔT(r,t)atrofthehotwire(5)Assumingr=r0,thesurfaceofthelineheatsourceandtheliquidhavethesametemperatureT(r0,t),andr2/(4αt)isverysmall.201qrT(r,t)T(r,t)TE()4k4ty021xeE(x)dyln(x)O(x)yid200020rq4tT(r,t)T(r,t)T[ln()...]4krC4tid020q4tT(r,t)ln()4krC3MATHMODELqdTk/4d(lnt)(6)DifferentiatebothsidesC=exp(γ)k:thermalconductivityoftheliquidα:thermaldiffusioncoefficientoftheliquid,E1(x):exponentialintegral4APPLICATIONReference:Thefirstapplicationofmulti-walledcarbonnanotubesnanofluidsconcentratedsolarcollectorsinthelowersection.(ChinesescholarsQiyuanLi)Result:Thecondensertypesolarcollectorbasedonnanofluidcaneffectivelyobtainsolarradiationenergy,istoapplynanotechnologyinalowcost,lowefficiencyinthefieldofheatingcollector(1)Concentratedsolarcollector;(2)TEMimagesofplasma-functionalizedmulti-walledcarbonnanotubes;(3)Uv-visiblespectraofcarbonnanotubestreatedwithKPSinDILiQ,ZhengC,MesgariS,etal.Experimentalinvestigationofananofluidabsorberemployedinalow-profile,concentratedsolarthermalcollector[C]//Micro+NanoMaterialsMOREAPPLICATIONSNanofluidshavegreatpotentialapplicationsinthefieldsof(1)energy(2)chemicalindustry(3)automobile(4)architecture(5)microelectronics(6)information(7)andsoonEngineering2DNanofluidicLi-IonTransportChannelsforSuperiorElectrochemicalEnergyStorageYanC,LvC,ZhuY,etal.Engineering2DNanofluidicLi-IonTransportChannelsforSuperiorElectrochemicalEnergyStorage[J].AdvancedMaterials,2017:1703909