Melting performance of rotational heat storage device for buildings: Design on pore parameters of metal foam

Thermal energy storage (TES) represents a promising technology for augmenting solar energy utilization by storing surplus heat for subsequent use, thereby enhancing overall efficiency. A principal challenge in TES systems lies in improving the heat transfer rate to ensure effective energy release during peak demand periods. Significant enhancements in melting efficiency can be achieved through the optimization of pore characteristics and rotational conditions. This study presents a numerical model of a porous structure-based rotating TES unit designed to evaluate the heat storage performance of a metal foam embedded phase change material under both static and rotating conditions. The analysis encompasses parameters such as charging time, heat storage capacity, progression of the melting front, temperature distribution, and velocity distribution, allowing for an assessment of how porosity, pore density, and rotation collectively affect the phase change process. The findings indicate that TES units with lower porosity demonstrate higher heat storage rates under both static and rotating conditions. In particular, the complete melting time of a rotating TES unit with 0.90 porosity is reduced by 88.4 % compared to a unit with 0.99 porosity. Moreover, rotation significantly influences high-porosity structure (0.99), resulting in a 28.4 % reduction in complete melting time. Additionally, high pore density metal foams, when combined with the forced convection effect brought by rotation, further optimize heat storage performance; however, the effect of pore density is comparatively less significant than that of porosity, which is attributed to the fact that compared with the combined influence of porosity on heat conduction and convection, the effect of pore density is reflected in the less influential natural convection. Ultimately, both metal foam and rotational motion enhance the charging efficiency and promote a more uniform melting process.