Experimental Investigation on Prototype Latent Heat Thermal Battery Charging and Discharging Function Integrated with Solar Collector

This paper reports the performance investigation of a newly developed Latent Heat Thermal Battery (LHTB) integrated with a solar collector as the main source of heat. The LHTB is a new solution in the field of thermal storage and developed based on the battery concept in terms of recharge ability, portability and usability as a standalone device. It is fabricated based on the thermal battery storage concept and consists of a plate-fin and tube heat exchanger located inside the battery casing and paraffin wax which is used as a latent heat storage material. Solar thermal energy is absorbed by solar collector and transferred to the LHTB using water as Heat Transfer Fluid (HTF). Charging experiments have been conducted with a HTF at three different temperatures of 68°C, 88°C and 108°C and three different flow rates of 30, 60 and 120 l/h. It is followed by discharging experiments on fully charged LHTB at three different temperatures of 68°C, 88°C and 108°C using HTF at three different flow rates of 30, 60 and 120 l/h. It is found that both higher HTF inlet temperature and flow rate have a positive impact on stored thermal energy. However, charging efficiency was decreased by increasing the HTF flow rate. The highest charging efficiency of 29% was achieved using HTF of 108°C at a flow rate of 30 l/h. Most of paraffin melted in this case, while part of the paraffin remained solid in other experiments. On the other hand, the results from discharging experiments revealed that both recovered thermal energy and recovery efficiency increased by either increasing the LHTB temperature or HTF flow rate. Highest recovered thermal energy of 5,825 KJ at 35% recovery efficiency achieved at LHTB of 108°C using 120 l/h of HTF.