Moving Bed Heat Exchanger for solar-driven steam cycles: Experimental validation of multiphase CFD simulations

Kurzfassung

A new design for a moving bed heat exchanger (MBHX) for heat recovery from particle-based thermal energy storage (TES) is investigated. A performance assessment of a prototype alongside a conventional tube bundle was carried out with a detailed look at the granular flow behavior as well as the overall thermal efficiency. Therefore, experiments as well as multiphase CFD simulations were conducted and subsequently compared. The geometrical arrangement of the heat exchanger tubes was 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 overall heat transfer. A good agreement with computational results was achieved for superficial granular velocities up to 2 mm/s, while for higher velocities, the thermal performance was overestimated.