Numerical investigation of multiple encapsulated plate-type phase change material thermal energy storage systems with S-shaped and parallel flow channels

Phase change thermal energy storage systems have attracted considerable attention because of their high energy storage density and excellent thermal stability, making them promising for industrial waste heat recovery and renewable energy utilization. In this study, a three-dimensional CFD model based on the enthalpy–porosity method was developed to investigate the thermal charging/discharging performance of encapsulated plate-type PCM thermal energy storage systems with S-shaped and parallel flow channels. The effects of plate spacing and HTF inlet velocity were systematically analyzed. The results show that reducing the plate spacing from 80 mm to 20 mm significantly enhances heat transfer and shortens the phase change time. For the S-shaped channel, increasing the HTF inlet velocity from 0.07 m/s to 0.28 m/s reduces the complete melting time by approximately 30%. Under identical PCM mass, HTF mass flow rate, inlet temperature, and plate spacing, the parallel flow channel achieves a thermal response that is 23.5% faster than that of the S-shaped channel. This improvement is mainly attributed to the more uniform temperature distribution and shorter heat transfer path, which enhance the overall thermal charging/discharging performance. The present study provides theoretical guidance for optimizing flow channel configurations in encapsulated plate-type PCM thermal energy storage systems.