Chapter 4 - Heat transfer in metal foam infused PCM: A case study

Abstract

A latent heat thermal energy storage system using phase change material is in research trend due to high energy storage density at isothermal phase change. However, its low thermal conductivity delays the phase change process. The recent and promising technique of incorporating a metal foam into the PCM enhances the heat transfer rate due to its high surface contact area and effective thermal conductivity. The enhancement in the phase change process due to the presence of metal foam is usually acknowledged in the literature, but it lacks the visual characteristics of the melting and solidification processes. As a result, in the present chapter, a case study with the objective of establishing and analyzing the PCM-metal foam composite performance is presented. It is also aimed to investigate the thermo-physics associated with the non-linear temperature distribution during the phase change processes of PCM using experimentation, visualization, and numerical techniques. A laboratory scaled PCM-metal foam composite-based thermal storage system is developed to visualize the phase interface and obtain the temperature profiles during the phase change processes. Also, a local thermal non-equilibrium linked enthalpy-porosity approach-based numerical code is modeled to compare phase change processes in pure PCM and PCM-metal foam composite. The results show that the large surface area contact between pores of metal foam and PCM in PCM-metal foam composite prompts notable conductive heat transfer enhancement. The natural convective heat transfer is also hampered due to the ligament structure. The melting and solidification times required for PCM-metal foam composite are 300min and 720min, respectively, which are reduced by 60min and 360min compared to the pure PCM. The influence of metal foam parameters on the thermal performance of PCM-metal foam composite is recommended to establish a trade-off between phase change time, storage capacity, and cost.