Charging–Discharging Characteristics of NaCl–KCl Eutectic Salt in a Thermal Box System

Solar radiation is a varied source of energy, and the mismatch between the availability of these sources and domestic energy demand is a major challenge that must be faced. Energy storage system can be considered as effective solution to overcome the challenge in solar energy utilization. In this work, a thermal box was prepared as energy storage testing apparatus by using a 5W lamp as the heat source located at the center of the box. In the middle of thermal box, the sample of phase change material (PCM) was placed and monitored in order to find out the charging and discharging characteristics. The purpose of this study was to investigate the charging and discharging performance of NaCl–KCl eutectic salt at various ratios. The specific heat capacity and density of all PCM samples were also tested during this investigation. The changes in temperature were observed through type-k thermocouple sensors equipped with data logger. In general, it can be concluded that reducing KCl portion in PCM slightly decreases the specific heat capacity. Experiment results showed that PCM-1 (eutectic salt with 30 wt% NaCl–70 wt% KCl) has the highest specific heat capacity, i.e., 6.93 J/g˚C. The highest rate of charging and discharging was exhibited by PCM-1, highlighting a positive effect of KCl content in eutectic salt.