Design of sensible and latent heat thermal energy storage systems for concentrated solar power plants: Thermal performance analysis

A shell-and-tube design with different thermal energy storage (TES) media was investigated as a promising TES system for a next generation concentrated solar power (CSP) plant. Sensible TES using graphite, latent TES using phase change materials (PCMs) and a hybrid of both were investigated. A two-dimensional transient heat transfer model was applied to simulate the thermal performance of multiple shell-and-tube TES modules connected in series. Considering the realistic operation of the CSP plant, an intensive numerical investigation was conducted to design and size the storage system. The TES systems studied were categorized as 3-PCM cascade, 5-PCM cascade, PCM-graphite-PCM hybrid and single graphite. All the PCMs considered in this paper have been experimentally proven as potential candidate storage media. It was found that all the TES systems studied, if well designed, can meet the CSP operational requirements. In comparison, single graphite storage is less problematic, but it has the lowest storage density (47.3 kWhr/tonne). By forming a PCM-graphite-PCM sandwich configuration, the energy density was increased to 60.9 kWhr/tonne and the storage effectiveness of this hybrid system is 70.7%, the highest among all the TES systems studied. (C) 2019 Elsevier Ltd. All rights reserved.