Predicted Charging and Discharging Efficiency of a Latent Heat Thermal 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. Two 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 a storage system geometry comprised of an outer shell containing PCM modules, a similar store in which the PCM in the modules is replaced with water and a water store. Isotherm plots are presented at selected times for both charging and discharging of the store geometry illustrating the effect of PCM melting and solidification on heat transfer to the PCM.
Keywords
Key-words. phase change energy storage, Numerical simulation