PCM, nano/microencapsulation and slurries: A review of fundamentals, categories, fabrication, numerical models and applications

Abstract

Sustainable energy is among the ever-increasing concerns in modern society. In this regard, thermal energy storage (TES) working based on latent heat has shown great potential by using phase change materials (PCM) with high heat capacity. However, PCM-TES has several challenges, such as material dispersion, possible chemical reactions with the environment and low thermal conductivity. Embedding PCM in a shell or porous network known as encapsulated PCM (EPCM) in both micro and nano sizes is proposed as a promising solution for these issues. In this study, a state-of-art review of PCM fundamentals, nano/micro EPCM, PCM slurries, coating materials, selection criteria, available fabrication methods, numerical models for latent heat simulation and prominent recent advances is presented. The review has addressed both experimental and numerical studies in detail by providing comparison tables and first of their kind figures. Based on the reviewed articles, chemical encapsulation methods, especially in-situ polymerization, provide a better particle size range and distribution with smooth surfaces, while they cause considerable environmental issues. Moreover, Paraffin wax is the most widely used core material mainly because of its affordability, while inorganic PCM and eutectics are suitable for high-temperature applications and refrigeration, respectively. Among available latent heat simulation models enthalpy-porous and apparent specific heat, that provide capturing solid–liquid interface and ease of use, respectively, are the highly used techniques in different industrial applications. Also, the important subjects and research gaps are detected, and suggestions for future investigations are provided.