Experimental Investigation on a Moving Bed Heat Exchanger used for discharge of a particle-based TES for CSP

Abstract

A newly developed moving bed heat exchanger (MBHX) for heat recovery from particle-based thermal energy storage (TES) was experimentally investigated. Centered towards solar thermal power applications, a performance assessment of a prototype was carried out with a detailed look on the granular flow behavior as well as its overall thermal efficiency. Additionally, the experimental results were compared to simulation results obtained from a numerical multiphase approach. The geometrical arrangement of the heat exchanger tubes is found to be a key parameter to performance improvements. The shape and size of stagnant zones developing on top of each tube was found to be influenced by the tube pitch and affects the velocity distribution and thus the heat transfer. Heat transfer coefficients up to 250 W/m²K were realized for high inlet velocities of sintered bauxite as granular medium. A good agreement with computational results was achieved for superficial granular velocities up to 2 mm/s.