- Thermal energy storage systems play a crucial role in improving the performance and reliability of renewable energy technologies, especially solar thermal systems. Among different storage techniques, latent heat thermal energy storage using Phase Change Materials (PCMs) has gained considerable attention due to its high energy storage density and nearly constant temperature during the phase transition process. This review paper presents a comparative analysis of two widely studied PCMs: paraffin wax (organic PCM) and calcium chloride hexahydrate (inorganic PCM) for solar thermal energy storage applications. The study evaluates their thermophysical properties, thermal performance, advantages, limitations, and suitability for different solar thermal applications. The paper also discusses recent advancements in composite PCMs and nano-enhanced PCM technologies aimed at improving thermal conductivity and stability. The comparative review indicates that paraffin wax offers excellent chemical stability, minimal supercooling, and long-term reliability, whereas calcium chloride hexahydrate provides higher thermal conductivity and energy storage density but suffers from phase separation and supercooling issues. The findings of this review can guide researchers in selecting suitable PCMs for solar thermal systems and highlight potential directions for future research.
KUMAR et al. (Sun,) studied this question.