Quantification of Phase Change Material Energy Storage Capability Using Multiphysics Simulations

Abstract

Organic phase change materials (PCMs) such as paraffins or unsaturated acids use the latent heat of melting for thermal energy storage as a passive cooling mechanism for portable electronics. Researchers have suggested that a PCM’s thermal energy storage capability is linked to its thermal properties, yet this connection has not yet been quantified. This study first uses group theory and known values from literature to obtain the thermophysical properties for a variety of paraffins and unsaturated acids. Then, multiphysics-based finite element analysis (FEA) is applied to determine the influence of these thermophysical properties on the PCM latent heat storage capability for a side heating configuration. The FEA models include melting and re-solidification, natural convection, conduction, and the monitoring of input and output periodic heat fluxes. The phase change was achieved through application of temperature-dependent viscosity and heat capacity relations. The thermal energy storage efficiency is defined as one minus the ratio of integrated output heat flux to the integrated input heat flux. The FEA results are used to provide predictions of thermal energy storage for a variety of PCMs for various aspect ratios under different heating conditions. Insights are gained in relating thermal storage efficiency to the system configuration.