Parametric Study Simulating the Daily Operation of a Thermocline Thermal Storage System

This work considers a packed-bed thermocline for use as an energy storage device in solar thermal power generation. A preliminary sizing procedure of a thermocline system for a 50 MWe plant is demonstrated along with predicted transient performance under various conditions. The inlet fluid temperatures are modeled as constant or time-dependent. The time-varying inlet conditions represent solar insolation variations throughout the day which roughly take a periodic form. Sinusoidal and periodic functions based on recorded data supply this inlet condition. A constant inlet temperature can be produced by circulating the heat transfer fluid in the collection field. Both possibilities are explored and the performance is compared for various charging time allotments. The study uses an efficient, accurate numerical scheme which has been developed to model the transient behavior of a porous thermocline tank. The model can be a useful tool for thermocline heat storage sizing. This can help take guess work out of the early stages of the design process as many simulations can be run efficiently and accurately.