Preliminary simulation results of a molten salt thermal storage thank for concentrated solar power

Abstract

Molten salt thermal storage systems play a critical role in concentrated solar power (CSP) plants, ensuring energy storage and dispatchability. Among these, thermocline tanks offer the potential for cost reduction, compared to the standard thermal storage system implemented in CSP plants: a two-tank solution (for hot and cold fluid, individually). This paper presents initial results from a Computational Fluid Dynamics (CFD) simulation of the 2.86 MWhth thermocline-tank installed at the EMSP – Évora Molten Salt Platform. The tank incorporates a filler material to enhance thermal stratification. The CFD model integrates the transport equations for mass, momentum and energy, along with closure models to account for the pressure drop imposed by the presence of the filler material and the heat transfer between the molten salts and the filler material. Validation of the model is conducted using experimental data from the literature. The simulation investigates the thermal performance of the tank during the discharging phase, where the axial temperature at the centerline of the tank was monitored periodically. The results were obtained for a simplified geometry of the tank as more improvements can still be made in future work to ensure the accuracy of the model.