A comprehensive review on development of eutectic organic phase change materials and their composites for low and medium range thermal energy storage applications

The excessively available solar energy storage is a very useful way to bridge the energy demand and its supply gap. This thermal energy storage (TES) can be done in the form of sensible or latent heat energy. The energy storage in the form of latent heat energy is better than the sensible energy storage in terms of operating temperature and storage density. Organic PCMs (O-PCMs) have great potential, especially from low to medium temperature-TES applications due to their several admirable thermal and physical characteristics. An appropriate melting point/enthalpy of O-PCMs is mainly required parameters for TES applications. In this regard, development of eutectic O-PCMs (EO-PCMs) by mixing two or more PCMs customizes the melting temperature and enthalpy so that they can be made suitable for targeted TES applications. However, their low thermal conductivity and leakage issue during the phase transition significantly restrict the practices of EO-PCM. A lot of studies were carried out to solve these changes by preparing them in form stable or shape-stabilized composite form. This review paper provides an insight on the development and thermo-physical properties of eutectic (binary and ternary) EO-PCMs as well as their composites as nano-enhanced and form stable phase change materials (FSPCMs). This paper also highlights recent studies published about the enhancement of thermal conductivity of EO-PCMs and their FSPCMs developed for LHTES practices. The use of EO-PCMs and their form stable composites in various applications, and challenges faced are also discussed. Finally, it outlooks the future directions for development of eutectic organic PCMs and their applications.