Enhancement of effective thermal conductivity in macro-encapsulate PCMs

Phase Change Materials (PCMs) present several advantages to store Thermal Energy Storage (TES). The high storage capacity permits a reduced volume of TES material compared to sensible heat systems and the quasi constant temperature during phase transition is really substantial for thermodynamic regulation in industrial processes. However, PCMs systems are generally limited by supercooling, segregation, corrosion and low thermal conductivity. The last drawback leads to low and decreasing power systems. One solution developed by CRISTOPIA ENERGY SYSTEMS is to encapsulate the PCM in spherical high density polyolefin capsules in order to develop the exchange surface with the heat transfer fluid. Another option is to associate a highly conductive component into the PCM, like graphite in order to increase its effective thermal conductivity. This paper presents the combination of these two methods simultaneously applied to commercial latent heat storage for cooling & industrial refrigeration and to a prototype solar thermosiphon hot water system.