FEATURES OF HEAT TRANSFER IN A FLAT POROUS MICROCHANNEL WITH THE SECOND ORDER SLIP BOUNDARY CONDITIONS

A. Avramenko, N. P. Dmitrenko, Y. Kovetska, O. I. Skitsko
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Abstract

The results of the study of heat transfer under forced convection in a flat porous microchannel taking into account the boundary conditions of slippage of the first and second order are considered. The simulation showed that with decreasing porosity the flow velocity in the central part of the microchannel and the slipping velocity on the wall decrease due to the increase in hydrodynamic resistance. Taking into account the influence of the boundary conditions of the second order shows that the magnitude of the velocity jump on the wall varies depending on the value of the parameter A2. The jump decreases with a positive value of A2, with a negative value - increases in comparison with the case A2 = 0 (first order boundary conditions). Qualitatively similar effects of porosity and second-order boundary conditions were also observed with respect to temperature profiles. The results of the calculation of the relative Nusselt number showed that the decrease in porosity contributes to the intensification of heat transfer. The dynamics of the change in the heat transfer coefficient with an increase in the Knudsen number indicates that an increase in the Prandtl number also leads to an improvement in the thermal interaction of the flow with the channel wall. The analysis of taking into account the boundary conditions of the second order showed that at small values of the Prandtl number (Pr ≤ 1) the influence of the parameter A2 was not observed. At A2 < 0 the effects of the boundary conditions of the second order lead to an increase in the relative Nusselt number, whereas at A2> 0 the value of the normalized Nusselt number decreases in comparison with the case A2 = 0 (boundary conditions of the first order).
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二阶滑移边界条件下平面多孔微通道的传热特性
考虑了考虑一阶和二阶滑移边界条件的平板多孔微通道强制对流换热的研究结果。模拟结果表明,随着孔隙度的减小,由于流体动力阻力的增大,微通道中部的流动速度和壁面的滑动速度减小。考虑二阶边界条件的影响,壁面上速度跳变的大小随参数A2的取值而变化。与A2 = 0(一阶边界条件)相比,跳跃性随正值A2而减小,随负值A2而增大。孔隙率和二阶边界条件也对温度剖面有类似的定性影响。相对努塞尔数的计算结果表明,孔隙率的减小有助于传热的加强。换热系数随克努森数增加的动态变化表明,普朗特数的增加也会导致流动与通道壁面的热相互作用的改善。考虑二阶边界条件的分析表明,在较小的普朗特数(Pr≤1)时,没有观察到参数A2的影响。在A2 < 0时,二阶边界条件的作用导致相对努塞尔数的增加,而在A2> 0时,与A2 = 0(一阶边界条件)相比,归一化努塞尔数的值减小。
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