Modeling of PCM-based enhanced latent heat storage systems using a phase-field-porous media approach

Abstract

This paper introduces a numerical study of latent heat storage systems, based on phase-change materials (PCMs) with various heat transfer enhancement techniques. In this, three alternative systems are considered: (1) a PCM-saturated open-celled metallic foam, (2) multiple immiscible PCM constituents with different melting temperatures and (3) a PCM-storage system with energy exchange enhancement using highly conductive fins. For the PCM-saturated porous medium, a biphasic model with intrinsically coupled and incompressible solid and fluid constituents is presented, where the modeling is based on the theory of porous media (TPM). A local thermal nonequilibrium model is used to describe the heat transfer process between the metal foams and the PCM, and the phase-field method (PFM) is employed to account for the phase-change process. It is shown in the numerical examples that the PFM–TPM approach is a reliable method to simulate the phase-change problems in different configurations considering the effect of natural convection on the macroscale, where a comparison with results from the literature-based experimental data and numerical methods has been carried out. It is also shown that the PFM–TPM formulations can, by simple modifications, be used to describe the PCM in nonporous ambient. In the latent heat storage systems, it is found that the studied methods can serve well in the efforts to increasing the melting rate and enhancing the heat storage process. It is shown that the PCM-saturated metallic foam provides the best enhancement among the other methods. Additionally, the energy charging rate depends on the arrangement type of the multiple PCMs.