Performance evaluation of a small-scale random packed bed latent thermal energy storage system

A small packed bed latent thermal energy storage system can achieve high charging and discharging power densities but is difficult to fabricate because the small phase change material capsules employed must be monodisperse. In this study, a microfluidic method is used to produce phase change material capsules to fabricate a small-scale random packed bed latent thermal energy storage system. The thermohydrodynamics of the system are analyzed. An equation is introduced to predict the frictional resistance of the system. The performance of the system is analyzed to evaluate the impacts of the flow rate and inlet temperature of the heat transfer fluid. Increasing the fluid flow rate from 0.2 L/min to 0.6 L/min increases the charging and discharging power densities to 257.47 kW/m3 and 143.3 kW/m3, respectively. However, the overall exergy efficiency decreases from 51.36 % to 38.44 % due to an increase in friction losses. As the fluid inlet temperature increases from 31 degrees C to 35 degrees C, the charging and discharging power densities reach 130.32 kW/m3 and 49.35 kW/m3. However, the overall exergy efficiency decreases from 51.36 % to 46.54 % due to an increase in the exergy dissipation.