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1、,Heat Transfer Enhancement,Nanofluid,1 INTRODUCTIONNanofluid： Nanofluid is a new kind of heat transfer medium, which disperses metal or non-metal nano powder into water, alcohol, oil and other traditional heat transfer medium, and makes it uniform, stable and highly conductive.Two parts of nanofluid
2、:Nanoparticles: metal, oxide, carbide, nitride, carbon nanotubes and other particles. Liquid base: water-soluble or water-insoluble liquid, water, alcohol, oil and other media,2 MECHANISM(1) Interaction and Collision Particle & particle, particles & liquid, particle & wall(2) Large Specific Surface
3、Heat transfer area between the particles and the suspension is correspondingly larger.(3) Brownian motion Nanoparticles disperse in liquid sufficiently(4) Large thermal conductivity(5) Particle concentration,3 MATH MODEL2.1 The traditional theoretical formula for the thermal conductivity of solid-li
4、quid mixtures2.2 Another model to calculate the thermal conductivity of solid-liquid mixtures with spherical particle,2.3 Measurement of thermal conductivity of nanofluids by transient hot-wire method(1)An equilibrium temperature of T0 the hot wire.(2)A constant heat flow q is suddenly added to the
5、hot wire.(3)T(r,t) at r of the hot wire(5)Assuming r=r0, the surface of the line heat source and the liquid have the same temperature T (r0, t), and r2/(4t) is very small.,3 MATH MODEL,(6)Differentiate both sides,C=exp()k :thermal conductivity of the liquid :thermal diffusion coefficient of the liqu
6、id,E1(x) :exponential integral,4 APPLICATION,Reference:The first application of multi-walled carbon nanotubes nanofluids concentrated solar collectors in the lower section.(Chinese scholars Qiyuan Li)Result:The condenser type solar collector based on nano fluid can effectively obtain solar radiation
7、 energy, is to apply nano technology in a low cost, low efficiency in the field of heating collector,Concentrated solar collector; (2) TEM images of plasma-functionalized multi-walled carbon nanotubes; (3) Uv-visible spectra of carbon nanotubes treated with KPS in DI,Li Q , Zheng C , Mesgari S , et
8、al. Experimental investigation of a nanofluid absorber employed in a low-profile, concentrated solar thermal collectorC/ Micro+Nano Materials,.,MORE APPLICATIONS,Nanofluids have great potential applications in the fields of(1)energy(2)chemical industry(3)automobile(4)architecture(5)microelectronics(6)information (7)and so onEngineering 2D Nanofluidic Li-Ion Transport Channels for Superior Electrochemical Energy Storage,Yan C , Lv C , Zhu Y , et al. Engineering 2D Nanofluidic Li-Ion Transport Channels for Superior Electrochemical Energy StorageJ. Advanced Materials, 2017:1703909,
