Abstract The pore scale and volume average analysis of the heat and fluid flow for a solid/liquid phase change in a 3D cubic Lattice Metal Frame (LMF) is performed numerically. The computational domain consists of 125 cells and the solid phase is consolidated. The governing equations which are continuity, momentum and energy equations for fluid phase and heat conduction equation for solid phase are solved. The volume average transport parameters are obtained from the pore scale results, then the volume average governing equations are also solved. A good agreement between the pore scale and volume average results is observed for the different Rayleigh numbers. A reverse heat transfer (heat transfer from Phase Change Material (PCM) to the solid frame) is observed in some cells (such as the center and upper cells) when the convection heat transfer is strong (i.e. R a = 10 6 ). In the reverse heat transfer region, the heat transfer rate between the solid frame and PCM takes negative value and the PCM temperature becomes greater than solid frame temperature. The change of sign of heat transfer rate and temperature difference between the solid frame and PCM does not occur simultaneously and this makes two discontinuities in the instant Nusselt number. Furthermore, the volume average governing equations are also solved by employing the interfacial heat transfer correlations reported in literature and the obtained results are compared with the results of present study. A good agreement between the results from pore scale analysis and the results based on some interfacial heat transfer correlations reported in literature is observed for wide range of Rayleigh number.

中文翻译：

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多孔介质固液相变化的综合孔隙尺度和体积平均研究

摘要 对 3D 立方晶格金属框架 (LMF) 中固/液相变的热量和流体流动进行了孔隙尺度和体积平均分析。计算域由 125 个单元组成，固相得到巩固。求解了流体相的连续性、动量和能量方程和固相的热传导方程的控制方程。体积平均输运参数是从孔隙尺度结果中获得的，然后也求解了体积平均控制方程。对于不同的瑞利数，观察到孔隙尺度和体积平均结果之间的良好一致性。当对流热传递很强（即 R a = 10 6 ）时，在某些单元格（例如中心和上部单元格）中观察到反向传热（从相变材料 (PCM) 到固体框架的热传递）。在逆向传热区，固体框架与PCM之间的传热速率为负值，PCM温度大于固体框架温度。固体框架和PCM之间的传热速率和温差符号的变化不是同时发生的，这使得瞬时努塞尔数有两个不连续性。此外，还利用文献报道的界面传热相关性求解体积平均控制方程，并将所得结果与本研究结果进行比较。