Design and modelling of mobile thermal energy storage (M−TES) using structured composite phase change material modules

This study concerns with a modelling led-design of a novel mobile thermal energy storage (M−TES) device aimed to address off-site industrial waste heat recovery and reuse in the UK. For the first time, salt-based composite phase change material (CPCM) modules were employed as the M−TES medium, utilizing air for charging and discharging. Two-dimensional (2D) and three-dimensional (3D) computational fluid dynamics (CFD) models were initially developed and validated against experimental data. The 2D model was used for parametric study to determine critical M−TES dimensions, followed by the 3D model for a comprehensive evaluation of thermal performance of the M−TES device. Key parameters examined included temperature uniformity within CPCM modules, evolution of air temperatures at the inlet and outlet, thermal storage capacities, charging/discharging rates, and specific efficiencies defined as heat transfer efficiencies and charging/discharging efficiencies throughout a complete cycle. The results under baseline conditions demonstrated that the M−TES device stored nearly 400 MJ of heat with a TES density of 560 kJ/kg after 10 h of charging, achieving an average CPCM temperature of 662 K. Approximately 97 % of the stored heat was released with the average outlet air temperature exceeding 468 K during the subsequent 10-hour discharging period. This work preliminarily verified the feasibility of the novel M−TES concept for integrating industrial thermal processing decarbonization with domestic heat supply.