Experimental Studies on Phase Change Material-Based Thermal Energy Storage System for Solar Water Heating Applications

Abundantly available solar energy utilization for domestic and industrial applications is hindered because of its intermittent nature. The thermal energy storage (TES) system using both sensible and latent heat has many advantages like large heat storage capacity in a unit volume and its isothermal behavior during the charging and discharging processes. Because of these advantages, in recent years, a lot of research work has been going on to overcome problems like low heat transfer the rates between heat transfer fluid and phase change material (PCM) in both charging and discharging processes of the PCM-based TES system. In the present experimental investigation results of a combined sensible and latent heat TES system integrated with a varying (solar) heat source is presented. Investigations are carried out in the TES system for different phase change materials (paraffin and Stearic acid) by varying HTF flow rates and for various sizes of spherical capsules (68, 58, and 38 mm in diameter). Experiments are performed in both charging and discharging processes. The results show that the 38 mm diameter spherical capsule shows better performance compared to spherical capsules of other sizes.