Study of thermal energy storage using phase change materials

The focus of this paper is to present the theoretical study of a latent heat thermal energy storage unit that uses phase change material (PCM) as storage medium. Paraffin is used as a PCM and water was used as the heat transfer fluid (HTF). The equations for the HTF and the PCM during the solid and liquid phase were obtained using the logarithmic mean temperature difference method. It has been concluded that, in the solid phase, the outlet temperature of the HTF increases because the energy that is being transferred from HTF to paraffin becomes lower over time. On the same principle as in the solid phase, during the liquid phase of the paraffin the outlet temperature of the HTF increases. Another conclusion was drawn regarding the heat exchange coefficient. The highest value was obtained during the melting phase, which was generated by the high value of the paraffin enthalpy of fusion.