Study of heat removal characteristics and energy consumption of shell-tube PCM energy storage units

Shell-tube PCM energy storage units are used in cold storage devices, the heat removal process is a critical factor influencing their performance. This study investigates the effects of cooling water temperature, water velocity, and tube shape on the heat removal process of shell-tube PCM energy storage units through both experiments and numerical simulations. The energy performance was analyzed based on the energy consumption of the chiller and water pump. The results show that the spiral tube has the highest heat removal rate and the greatest resistance loss, but also the lowest chiller energy consumption. Additionally, the study found that for every 1 °C increase in cooling water temperature, the heat removal time increases by approximately 13.9 %, the energy efficiency ratio (EER) decreases by about 9.5 %, and the chiller energy consumption decreases by about 5 %. Higher cooling water velocity can improve the heat removal rate but reduces the EER. Beyond tube shape, both the cooling water temperature and velocity affect the PCM liquid fraction distribution inside the shell, thereby influencing the energy consumption during the sensible heat removal of solid-state PCM. The EER of the sensible heat removal process for solid-state PCM is lower compared to that of liquid and hybrid states.