纳米颗粒微运动强化纳米流体热导率的理论研究

On the theoretical study of nanoparticle micro-movements to strengthen the thermal conductivity of nanofluids

理论推导了纳米颗粒布朗运动、热泳和渗透泳产生有效热导率的计算公式,定量讨论了三种机制的微运动对纳米流体有效热导率的影响.通过比较和分析,结果表明布朗运动对纳米流体有效热导率的贡献是最主要的,其作用效果是另外两种机制的106-108倍;三种运动产生的有效热导率都随颗粒体积分数的增大而增加;布朗运动产生的有效热导率随颗粒粒径的增大而减小,热泳和渗透泳对有效热导率的贡献与粒径大小无关;当纳米流体热流通量越高时,热泳和渗透泳产生的有效热导率越大.

This text theoretically deduced the calculation formula of the effective thermal conductivity induced by the Brownian motion,thermo-phoresis and osmo-phoresis of nanoparticle.It was quantitatively discussed that the three kinds of micro-movements influence the effective thermal conductivity of nanofluids.By comparing and analyzing,the results indicate that the Brownian motion effect was found to be more significant by factors of and when compared to thermo-phoresis and osmo-phoresis,respectively.For a given particle size,the thermal conductivity increases with particle volume concentration.The Brownian-motion-induced thermal conductivity decreases with particle size.But,thermo-phoresis-and osmo-phoresis-induced thermal conductivity relations are independent of particle size.Furthermore,the thermo-phoresis and osmo-phoresis-induced thermal conductivity increases with heat flux.