Analytical considerations of slip flow and heat transfer through microfoams in mini/microchannels with asymmetric wall heat fluxes
Analytical considerations of slip flow and heat transfer through microfoams in mini/microchannels with asymmetric wall heat fluxes
复制标题
具有不对称壁热通量的微型/微通道中通过微泡沫的滑流和传热的分析考虑
DOI：
10.1016/j.applthermaleng.2015.09.068
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发表时间：
2016
影响因子：
6.4
通讯作者：
Xu Z. G.
中科院分区：
文献类型：
--
作者：
Xu H. J.;Zhao C. Y.;Xu Z. G.
在均匀和非对称热流密度条件下，对微泡沫填充微通道内的强迫对流进行了解析研究。重点考虑了速度滑移、热滑移、局部热非平衡(LTNE)效应以及夹在微泡中的两个平行板上的非对称热流密度。对于热流密度不同的两个壁面，基于自耦合条件，边界上的固体和流体温度相等。推导了固体和流体的速度和温度的显式表达式，解析解与已有文献符合得很好。该解可以在较宽的克努森数和HF比范围内预测多孔微通道的速度、温度、摩擦损失和热性能。随着Knudsen数的增大，摩擦因数逐渐减小，滑移区的减小幅度很大。随着形状因子的增大，当形状因子较小时，无因次压降急剧减小，而当形状因子较大时，其值逐渐接近1。随着Knudsen数的增加，存在最大Nusselt数。增加有效Biot数或降低导热比可强化换热。解析解在轴ξ= 1上的区域0 <；ξ<； + ∞上对称。
Forced convection in a mini/microchannel filled with microfoam is analytically studied in the condition of uniform but asymmetrical heat fluxes. Velocity slip, thermal slip, local thermal non-equilibrium (LTNE) effect, and asymmetric heat fluxes imposed on the two parallel-plates sandwiching the microfoams are especially considered. For two walls with different heat fluxes, solid and fluid temperatures at the boundary are equal to each other based on self-coupling conditions. Explicit expressions for velocity and temperatures of solid and fluid are derived and the analytical solution agrees well with existing references. This solution can predict velocity, temperatures, friction loss and thermal performance of porous microchannel for wide ranges of Knudsen number and HF ratio. With the increased Knudsen number, the friction factor gradually decreases and the decreasing amplitude in slip flow region is very large. With the increased shape factor, the dimensionless pressure drop sharply decreases for small shape factor, while its value gradually approaches 1 for large shape factor. A maximum Nusselt number exists with the increase in Knudsen number. Heat transfer can be enhanced by increasing effective Biot number or decreasing thermal conductivity ratio. The analytical solution is symmetrical on the axisξ= 1 in the region 0 <ξ< + ∞.