A Review of Phase Change Materials as an Alternative for Solar Thermal Energy Storage

Abstract

This paper reviews the recent trends for storing thermal energy using phase change materials and characterization of their thermal and other properties. Solar energy is abundantly available and can be utilized effectively for thermal energy storage using phase change materials (referred as PCMs hereafter). There are various techniques available for storing surplus solar thermal energy like pressurized water storage technique, etc. but phase change materials have emerged as a completely different and effective alternative in the field of solar thermal energy storage. Wide range of phase change materials is available with a large range of melting and solidifying temperatures. Many considerations of selecting a particular phase change material for a given application have been discussed in this paper. Considerations range from thermo-physical properties, data generated through various experiments, heat transfer processes, concentration of various constituents, etc. Six aspects pertaining to PCMs have been discussed in this paper. First section reviews the types of PCMs. In second section, various encapsulation techniques have been discussed. Range of operational temperatures is reviewed in third section. Fourth section is about characterization of various properties affecting the performance of PCMs. PCMs utility in storing the surplus thermal energy in solar thermal applications has been discussed in fifth section. Sixth section covers the economic considerations and other applications of PCMs.