Numerical Model for Solar Thermal Collectors and Thermal Energy Storages Based on Phase Change Slurry
Abstract
The efficiency of conventional solar thermal collectors and related thermal energy storages is often reduced by the requirement for high irradiation levels and the heat losses due to the relatively high temperature of the heat transfer fluid. In order to overcome those limitations, a solar thermal system capable of working at low temperatures through the exploitation of latent heat storage is presented in this paper. The proposed system was based on a novel heat transfer fluid and storage media, composed by a mixture of water and micro- encapsulated phase change material (PCM), named Phase Change Slurry (PCS). This paper introduces a numerical model capable of accurately describe the physical process and the dynamics of the proposed technology (collector, thermal energy storage and control logics). Results were validated by means of experimental tests and a long-term monitoring on a real full-scale prototype. Furthermore, experimental tests were performed to carry out the actual PCS thermo-dynamical properties that are strongly dependent on the concentration of micro-capsules in the heat transfer fluid.