Predicted Charging Efficiency of a Latent Heat Energy Storage System Linked to a Solar Thermal Collector System
Abstract
The high latent heat of phase change allows a small volume of phase change material (PCM) to store a significant amount of energy at constant temperature compared to simple sensible energy storage. This enables the size of thermal energy storage systems to be reduced. Charging and discharging rates of a PCM system are limited by the relatively low thermal conductivity of the PCM when solid. Finned metal heat transfer surfaces or an embedded metal matrix may effectively address this problem. Two and three dimensional transient finite volume models have been developed that allow prediction of heat transfer to and from a PCM, with simulation of the progress of the phase transition front and the free convective heat transfer that occurs within the liquid phase. Simulation results are presented for selected system geometries with and without fins incorporated to enhance heat transfer to the PCM. Isotherm plots are presented for both charging and discharging of PCM modules within a thermal energy store.