Thermal Performance Analysis of Multi-Layer Thermal Energy Storage Tank Using Different Phase Change Materials

Abstract

A thermocline thermal energy storage (TES) tank is the key element of storing thermal energy for concentrated solar power (CSP) plants. This paper focuses on the numerical analysis of the single-phase thermal energy storage (TES) and the two-phase latent heat thermal energy storage (LHTES) for single-layered and multi-layered phase change materials (MLPCMs) using molten salt, FLiNaK, a eutectic mixture of 46.5%LiF, 11.5%NaF, and 42% KF as the heat transfer fluid. The heat transfer module for the computational domain is analyzed using the Dispersion-Concentric model which is based on energy equations and is solved by the finite element method. The results of the TES were compared with that of an existing numerical study in the literature, and they were found to be reasonably in agreement. The high thermal conductivity and specific heat capacity offered to the LHTES by the PCMs result in the best charging and discharging thermal cycle. The study helps us to understand the thermal behavior of temperature inside the tank for different PCMs and from the comparative thermal analysis of the study, it is possible to choose the best PCM among the alternatives.