Numerical Study on the Effect of the Elliptical Tube Surface Temperature Changes inside a Circular Cylinder on the Melting Performance of Phase Change Material-Based Latent Heat Storage System

In this study, the impact of surface temperature changes of elliptical tubes within a circular cylinder was numerically analyzed on the thermal performance of a latent heat storage system(LHTES) using phase change materials. The enthalpy-porosity technique was employed to simulate the phase change process, and a dimensionless analysis, including Stefan number, Fourier number, and Rayleigh number, was conducted to evaluate the heat transfer and phase change processes. The melting rate and patterns of the phase change material, according to the tube surface temperature, were quantitatively analyzed and used to develop a new correlation. Additionally, the heat transfer efficiency was evaluated, showing that lower tube surface temperatures lead to higher efficiency, while higher tube surface temperatures result in lower efficiency due to the conversion of some energy to the sensible heat of the liquid PCM.