Analysis of a Latent Thermocline Energy Storage System for Concentrating Solar Power Plants

The primary purpose of a thermal energy storage system in a concentrating solar power (CSP) plant is to extend the operation of plant at times when energy from the sun is not adequate by dispatching its stored energy. Storing sun’s energy in the form of latent thermal energy of a phase change material (PCM) is desirable due to its high energy storage density which translates to less amount of salt required for a given storage capacity. The objective of this paper is to analyze the dynamic behavior of a packed bed encapsulated PCM energy storage subjected to partial charging and discharging cycles, and constraints on charge and discharge temperatures as encountered in a CSP plant operation. A transient, numerical analysis of a molten salt, single tank latent thermocline energy storage system (LTES) is performed for repeated charging and discharging cycles to investigate its dynamic response. The influence of the design configuration and operating parameters on the dynamic storage and delivery performance of the system is analyzed to identify configurations that lead to higher utilization. This study provides important guidelines for designing a storage tank with encapsulated PCM for a CSP plant operation.