An experimental investigation of the charging process of thermal energy storage system filled with PCM and metal wire mesh

Abstract

The low thermal conductivity of the phase change materials limits the performance of latent heat thermal energy storage systems. The thermal conductivity of the phase change materials can be enhanced by incorporating a highly conductive porous medium. The studies available in the literature are limited to the application of metal foams in different geometries of latent heat thermal energy storage systems. In the present study, experimental investigations have been carried out to study the effect of adding copper wire mesh having two different porosities (i.e., 75% and 87%) and pore density of 16 pores per inch inside a cylindrical latent heat thermal energy storage system subjected to three different isothermal surface temperatures. The effect of adding metal wire mesh and isothermal surface temperatures on the heat flux, Nusselt number, and energy stored during the melting process are analysed. The results indicate that embedding copper wire mesh into the phase change materials leads to a uniform temperature distribution inside the latent heat thermal energy storage system, which is more pronounced at lower porosity. The maximum improvement in the charging times by using copper wire mesh with porosities of 87% and 75% are to be 17% and 24%, respectively. Moreover, it is observed that by using composite phase change materials (i.e., a combination of phase change material and metal wire mesh) the rate of heat transfer and energy stored is increased due to higher effective thermal conductivity of composite phase change materials. A correlation is proposed to predict the Nusselt number for different cases of the experiment. It is anticipated that these prospective results will be valuable for optimizing the energy transport in practical thermal energy storage applications.