The microencapsulation, thermal enhancement, and applications of medium and high‐melting temperature phase change materials: A review

Microencapsulated phase change materials (MEPCMs) have made tremendous advancements in recent years, owing to their increased demand for a variety of energy storage applications. In this paper, current microencapsulation techniques, enhancement, and use of medium- and high-melting phase change materials (PCMs) are reviewed, as well as their potential benefits and limitations. The most frequently employed PCMs for medium- and high-temperature applications were recognized as salt-based, metallic, inorganic compound, and eutectic. Meanwhile, polymethyl methacrylate (PMMA), polystyrene-butylacrylate (PSBA), polyethyl-2-cyanoacrylate (PECA), and polyurethane were widely used as polymer shell materials for encapsulating medium- and high-melting point PCMs via chemical method, whereas inorganic silica shell was synthesized via various techniques. Hydrolysis followed by heat-oxidation treatment has been extensively studied since 2015 to encapsulate either metal or alloy within Al2O3 shells. Different techniques were developed to generate void between core and shell material to accommodate volume expansion during phase transition. Numerous approaches, including the incorporation of metal particles, carbon, and ceramic, have been found as ways to enhance the thermal performance of PCMs. Multiple storage arrangements were also established to be an effective way of enhancing the overall efficiency of medium-high melting PCM storage systems. Finally, the paper highlights the potential of medium- and high-melting temperature PCMs for solar power generation, solar cooking, and industrial waste heat recovering applications.