Partially filled shell and tube TES comparison among different metal foam configurations filled by PCM

Thermal energy storage (TES) systems based on phase change materials (PCMs) represent an effective solution for enhancing thermal energy management. The increasing need to reduce carbon emissions has highlighted the importance of thermal storage systems in improving energy efficiency and integrating renewable energy sources. Thermal energy storage (TES) systems can be classified into three main categories: sensible, latent, and thermochemical storage systems. Among them, the latent heat thermal energy storage systems (LTESs) stand out. In comparison to sensible TESs, for instance, latent ones exhibit higher thermal energy storage density per unit mass and operate within a smaller temperature range due to phase change at quasi-constant temperatures. They are based on PCMs that have low thermal conductivities and limited heat transfer capabilities, but these low properties values can be increased by different techniques. For instance, by using porous media like metal foams. Considering the use of the metal foams, the thermal conductivity of the PCM significantly increases, due to the presence of a fast-absorbing energy zone characterized by low thermal resistance within the TES system. However, a slight reduction in the heat storage capacity of the system could occur due to metal foam presence. This study investigates a novel shell and tube configuration of an LTES system employing paraffin wax as the PCM and metal foam to improve thermal conductivity. The system consists of a shell and tube configuration, partially filled with two distinct regions: one containing metal foam impregnated with PCM and the other with only PCM. Two different spatial arrangements of these regions are explored: (i) a concentric configuration, where the regions are divided along the radial direction, and (ii) a disk-like configuration, where the regions are separated along the vertical direction, resembling a finned structure where the PCM is contained within the fins. The Brinkman-Forchheimer-extended Darcy model is applied to analyze the metal foam made of aluminum saturated with paraffin, RT50, assuming the Local Thermal Equilibrium (LTE). Additionally, the enthalpy-porosity method is used to model the phase change process in paraffin wax. The Ansys-Fluent commercial code is employed for numerical solutions to the governing equations. A comparative numerical analysis is conducted to evaluate the thermal performance of these configurations in terms of heat transfer enhancement, melting time reduction, and energy storage efficiency. The results provide insights into the optimal design of LTES systems, highlighting the influence of spatial distribution of metal foam on the thermal response of the system.