A comprehensive pore scale and volume average study on solid/liquid phase change in a porous medium. (October 2020)

• Record Type: Journal Article
• Authors: Wang, Chunyang; Mobedi, Moghtada
• Is Part Of: International journal of heat and mass transfer. Volume 159(2020)
• Publication Date: 2020-10
• Subjects: Solid/liquid phase change -- Porous media -- Pore scale analysis -- Volume average technique -- Local thermal non-equilibrium; Heat -- Transmission -- Periodicals; Mass transfer -- Periodicals; Chaleur -- Transmission -- Périodiques; Transfert de masse -- Périodiques; Electronic journals; 621.4022
• DOI: 10.1016/j.ijheatmasstransfer.2020.120102
• Languages: English
• ISSNs: 0017-9310

Abstract

Highlights: Good agreement exists between the pore scale and volume average results for the phase change in cubic lattice metal frame. For the high values of Rayleigh number, a reverse heat transfer from PCM to solid frame is observed in some cells. Two discontinuities during the variation of local interfacial Nusselt number with time in cells are observed. The comparison of the present results with correlations in literature for interfacial heat transfer correlations is done. 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.