多孔泡沫内纳米流体非平衡传热及体积分数分布

Non-equilibrium convective heat transfer and volume fraction distribution of nanofluid in porous foams

中文关键词: 纳米流体  金属泡沫  对流  传热  纳米颗粒体积分数

英文关键词: nanofluid  metal foam  convection  heat transfer  volume fraction of nanoparticle

中文摘要:

      研究了纳米流体在金属泡沫内对流换热,建立了局部非热平衡数学模型,得到了金属泡沫内纳米流体速度、温度和纳米颗粒体积分数分布,分析了纳米流体和金属泡沫的强化换热效果。当使用纳米流体或在通道内填充金属泡沫时,截面速度和温度变得更均匀。随着纳米颗粒体积分数的增大,努塞尔数先增大然后又逐渐减小,即存在一个合适的体积分数能使换热效果达到最好；当金属泡沫孔隙率减小时努塞尔数也会减小,有利于换热的进行。纳米流体和金属泡沫对换热具有明显强化作用,但压降随纳米颗粒体积分数增大而急剧增大。此外,还考虑了布朗扩散和热泳扩散等因素的影响。

英文摘要:

      The convective heat transfer of nanofluid in metal foam was studied. A mathematical model was established based on the local thermal non-equilibrium assumption and distribution of velocity, temperature and nanoparticle volume concentration were obtained. Heat transfer enhancement effects of nanofluid and metal foam were analyzed. Crosssectional velocity and temperature distribution becomes more uniform when using nanofluid or metal foam in a channel. The Nusselt number increases first and then decreases with an increase in the nanoparticle volume concentration, namely, there is an appropriate nanoparticle concentration which leads to the best Heat transfer enhancement effect. The Nusselt number decreases with an increase in the foam porosity, so a higher porosity is beneficial for enhancing the heat transfer. In addition, the effects of Brown motion and thermophoresis were also discussed.