Performance comparison and enhancement of the thermal energy storage units under two expansion methods

To improve the performance of the basic thermal energy storage unit, two expansion methods, modular combination and linear structural expansion, are proposed and compared through numerical simulations. The impacts of the two expansion methods on the performance of the storage units are compared by investigating the thermal storage and release processes. Following the numerical study, both expansion methods can increase the heat storage capacity and airflow rates compared to a basic phase change material (PCM) storage unit linearly. However, the linear structural expansion method will increase the PCM melting time from 147 min to 367 min when the heat storage capacity of the basic unit is increased two times, which is about 2.5 times longer duration than using the modular expansion method. As for the heat release process, the results indicate that thermal release performance using linear structural expansion is lower than that of the modular combination along with a decrease in heat release efficiency of about 32.53 %. In conclusion the modular combination method is proved to be more efficient compared to the linear structural expansion method for improving the performance of the PCM storage units.