The phase change material should possess the following thermodynamic properties:
* Melting temperature in the desired operating temperature range
* High latent heat of fusion per unit volume
* High specific heat, high density, and high thermal conductivity
* Small volume changes on phase transformation and small vapor pressure at operating temperatures to reduce the containment problem
* Congruent melting
Kinetic properties
* High nucleation rate to avoid supercooling of the liquid phase
* High rate of crystal growth, so that the system can meet demands of heat recovery from the storage system
Chemical properties
* Chemical stability
* Complete reversible freeze/melt cycle
* No degradation after a large number of freeze/melt cycle
* Non-corrosiveness, non-toxic, non-flammable and non-explosive materials
Economic properties
* Low cost
* Availability