Numerical Analysis of Total Energy Storage of Nanofluidized Heat Transfer Fluid in Thermocline Thermal Energy Storage System

An important factor to enhance the concentrating solar power plant’s efficiency relies on the thermal energy storage (TES) system. A single-tank thermocline storage in which both, the hot and cold, fluids are contained in the same tank separated by density difference is investigated. In theory, the overall efficiency and storage capacity of a TES system depends on the thermodynamic properties of heat transfer fluid (HTF). In this study, Solar Salt® is used as both the HTF and TES medium. The operating temperatures used in the system analysis range from 300°C to 500°C. The working temperatures will determine the efficiency of storage and the heat storage capacity. To potentially increase the heat capacity and thermal conductivity values, the molten salt has been doped with SiO₂, Al₂O₃, CuO, Ag and ZnO nanoparticles at different concentrations. The variation of the thermodynamic properties of Solar Salt® along with the performance of single-tank TES system were evaluated and compared to obtain the best working composition. The goal of this study is to comprehend and adapt the behavior of the molten salt doped with nanoparticles. In this study, the effective heat capacity, thermal conductivity, density, and viscosity of Nano-fluid are calculated and used in the models to approximate the total energy storage capacity. The models were evaluated by numerical analysis using finite volume computational fluid dynamics software. The numerical results are compared with experimental results in literature.