Simplified modeling and parametric analysis of modular heat storage tanks integrating low-melting-point metallic phase change materials

In recent years, phase change materials (PCMs) have attracted significant attention for thermal energy storage (TES) applications due to their high energy storage density and operational reliability. Nevertheless, efficient and rapid modeling methods for low-melting-point metal PCMs are still limited. Traditional commercial simulation models suffer from heavy software dependence and poor portability. This work proposes a modular thermal energy storage tank with low-melting-point metal PCM, and develops a compilable lightweight numerical analysis model based on self-programmed codes. Gallium is chosen as the PCM owing to its low melting point, high specific latent heat capacity, and superior thermal conductivity. The heat storage rate and overall thermal performance are found to be substantially enhanced by higher flow rates and inlet thermal conditions, which consequently raise the fluid temperature at the outlet. When the flow velocity increases from 0.005 m/s to 0.025 m/s and inlet temperature rises from 35 °C to 60 °C, the heat storage saturation time is reduced by 47.4% and 94.4%, respectively. In addition, when the fill height of the TES material is too low, it limits the storage capacity and accelerates the decline of the heat storage rate as well as the evolution of the phase transition front. This lightweight modeling method and its results can provide theoretical guidance for structural design and parameter optimization of phase change thermal storage systems, and deliver technical support for embedded deployment and engineering practice.