Thermodynamic Modelling of a Tes Packed Bed Tank: Exploring the Influence of Different Particle Sizes on Overall Performance

Abstract

Concentrated solar power (CSP) coupled with thermal energy storage (TES) technology is widely utilized in power generation. To enhance heat transfer efficiency during thermal charging and discharging, packed bed TES systems have been developed for their high heat transfer rates and large surface areas. However, existing thermodynamic models often overlook size effects and pressure drops caused by particle diameter variations. This study introduces a two-solid-phase model to address these limitations in packed bed TES systems. Using molten salt and natural volcanic ash as the heat transfer fluid and solid filler, respectively, the model evaluates size effects during charging and discharging. Smaller particle sizes notably increase heat transfer area, enhancing efficiency. Despite higher energy storage density due to improved packing efficiency, the system experiences increased pressure drop due to reduced void fraction. The pressure drop exhibits an exponential relationship with particle size changes. Additionally, the thermocline within the packed bed, where the steepest pressure gradients occur, requires careful consideration. This research underscores the impact of particle size on packed bed performance, providing critical insights for next-generation TES bed design.

Keywords: Thermal energy storage, Sensible heat, Packed bed, Particle size, thermodynamic model, Pressure drop