Research progress on phase change heat storage exchangers for solar thermal utilization

Phase change materials (PCMs) leverage their high energy density and thermal stability advantages in solar thermal storage systems to effectively address the temporal and spatial mismatch between energy supply and demand. This paper presents a systematic review of the critical role of PCMs in solar energy utilization, with a focus on the structural classification of thermal storage exchangers (e.g., shell-and-tube, plate, finned tube, and spiral tube types). It also evaluates the thermal conductivity efficiency and scalability potential of various structures. In order to address the challenge of PCMs' inherently low thermal conductivity, the study proposes strategies to enhance thermal response speed by incorporating high-thermal-conductivity fillers (such as expanded graphite and nanoparticles) and optimizing encapsulation techniques (such as microencapsulation). Furthermore, it delves into the potential of structural optimizations, such as the incorporation of irregular fins and spiral channels, to enhance the efficacy of heat exchange. Subsequent research endeavors should prioritize the development of novel high-performance PCMs, the conceptualization of intelligent thermal management systems, and advancements in multi-energy complementary integration technologies. These efforts are crucial for propelling the commercial implementation of phase change thermal storage technology in domains such as solar building integration and industrial waste heat recovery.