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A nanofluid is a fluid containing nanometer-sized particles, called nanoparticles. These fluids are engineered colloidal suspensions of nanoparticles in a base fluid. The nanoparticles used in nanofluids are typically made of metals, oxides, carbides, or carbon nanotubes. Common base fluids include water, ethylene glycol〔(【引用サイトリンク】title=Argonne Transportation Technology R&D Center )〕 and oil. Nanofluids have novel properties that make them potentially useful in many applications in heat transfer,〔Minkowycz, W., et al., (Nanoparticle Heat Transfer and Fluid Flow ), CRC Press, Taylor & Francis, 2013〕 including microelectronics, fuel cells, pharmaceutical processes, and hybrid-powered engines, engine cooling/vehicle thermal management, domestic refrigerator, chiller, heat exchanger,in grinding, machining and in boiler flue gas temperature reduction. They exhibit enhanced thermal conductivity and the convective heat transfer coefficient compared to the base fluid. Knowledge of the rheological behaviour of nanofluids is found to be very critical in deciding their suitability for convective heat transfer applications〔S. Witharana, H. Chen, Y. Ding; Stability of nanofluids in quiescent and shear flow fields, Nanoscale Research Letters 2011, 6:231 http://www.nanoscalereslett.com/content/6/1/231/〕 In analysis such as computational fluid dynamics (CFD), nanofluids can be assumed to be single phase fluids. However, almost all of new academic paper use two-phase assumption. Classical theory of single phase fluids can be applied, where physical properties of nanofluid is taken as a function of properties of both constituents and their concentrations. An alternative approach simulates nanofluids using a two-component model. The spreading of a nanofluid droplet is enhanced by the solid-like ordering structure of nanoparticles assembled near the contact line by diffusion, which gives rise to a structural disjoining pressure in the vicinity of the contact line. However, such enhancement is not observed for small droplets with diameter of nanometer scale, because the wetting time scale is much smaller than the diffusion time scale. ==Synthesis== Nanofluids are produced by several techniques they are, 1.Direct Evaporation (1 step), 2.Gas condensation/dispersion (2 step), 3.Chemical vapour condensation (1 step), 4.Chemical precipitation (1 step). Several liquids including water, ethylene glycol, and oils have been used as base fluids. Nano-materials used so far in nanofluid synthesis include metallic particles, oxide particles, carbon nanotubes, graphene nano-flakes and ceramic particles.〔(【引用サイトリンク】title=An Error Occurred Setting Your User Cookie )〕〔(【引用サイトリンク】title=A review on preparation methods and challenges of nanofluids )〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Nanofluid」の詳細全文を読む スポンサード リンク
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