Growing energy consumption and the continuous reduction of conventional fuel reserves have increased research interest in alternative thermal energy technologies based on renewable resources. Among the available renewable resources, solar thermal energy has gained significant attention because of its easy availability, clean operation, and suitability for low-temperature heating applications. Despite its advantages, variation in solar radiation during daytime operation affects the continuity of thermal energy availability and limits the effective utilization of solar heating systems. To address this issue, thermal energy storage systems are incorporated into solar thermal applications to store excess heat energy during periods of high solar intensity and release it when solar radiation becomes unavailable or insufficient. In the present research work, a solar thermal energy storage system integrated with Phase Change Material (PCM) is experimentally investigated to improve thermal storage performance and heat utilization efficiency. Paraffin wax is employed as the thermal storage material owing to its stable phase transition behavior, compatibility with solar heating operation, and moderate melting temperature range. The study focuses on analyzing the charging and discharging behavior of the PCM, thermal energy storage capacity, temperature stabilization characteristics, and overall thermal efficiency of the solar thermal system. Experimental observations are carried out under different operating conditions by monitoring inlet temperature, outlet temperature, PCM temperature variation, and heat retention duration during charging and discharging cycles. The thermal performance of the PCM-integrated system is compared with a conventional solar thermal system without PCM storage. The experimental analysis showed noticeable improvement in thermal storage performance, slower temperature reduction during discharging, and longer heat availability after reduction in solar intensity. The integrated PCM arrangement additionally helped maintain stable operating temperature and reduced the rate of thermal energy loss. The study demonstrates the effectiveness of latent heat storage techniques for improving thermal utilization and enhancing continuity of heat supply in solar thermal applications. The experimental findings confirm that PCM-assisted solar thermal energy storage systems can effectively improve renewable energy utilization and provide a reliable solution for sustainable thermal management applications. Hence, PCM-assisted solar thermal systems can provide an efficient and practical approach for improving heat storage performance in small-scale domestic and industrial thermal applications.
Chavhan et al. (Mon,) studied this question.