Optimization of an encapsulated phase change material thermal energy storage system

• Presents a computational analysis of a thermocline energy storage system with encapsulated phase change materials.
• Presents a systematic nondimensional analysis on the effects of design and operating parameters on the performance.
• Presents design windows on the geometry of the storage system based on practical constraints.
• Presents optimal geometry and operating conditions so as to minimize storage cost subject to practical constraints.

Thermal energy storage enables uninterrupted operation of a concentrating solar power (CSP) plant during periods of cloudy or intermittent solar availability. This paper presents a transient computational analysis of an encapsulated phase change material (EPCM) thermal energy storage (TES) system for repeated charging and discharging cycles to investigate its dynamic response. The influence of the design and operating parameters on the dynamic charge and discharge performance of the system is analyzed to identify operating windows that satisfy technoeconomic targets of storage cost less than $15/kW ht, round-trip exergetic efficiency greater than 95%, charge time less than 6 h and a minimum discharge period of 6 h. Overall, this study illustrates a methodology for design and optimization of encapsulated PCM thermal energy storage system (EPCM-TES) for a CSP plant operation.