There are different types of PCMs available in the market and they all have their own advantages and disadvantages. Most frequent used PCMs are hydrate salt ( inorganic PCM), salts with water ( inorganic PCM ), Parrafin based PCM (organic PCM), Bio PCM ( organic PCM) including fatty acids, fatty alcohols and other fatty acid derivatives.
Inorganic PCMs are cheap in price but they natually have problems in subcooling, phase seperation, easy to lose water. Only engineered PCMs with additive can be used as commerical PCM. Parrafin based PCM are very stable with high latent of heat, but compared to inorganic PCM, they have low density and low conductivity. Bio PCM has the similar problem with that of parrafin.