Hydrodynamic and thermal analysis of a novel indirectly heated moving packed bed receiver for concentrated solar power

This work presents a combined experimental and computational investigation of a novel gravity-driven dense-phase moving packed bed solar receiver for concentrated solar power (CSP) applications. Unlike conventional particle receivers such as fluidised beds, falling-particle curtains, or rotating receivers, the proposed design uses a flat, indirectly heated conduit to promote particle-wall contact and sub-millimetre particles to enhance heat transfer. A multiphase Eulerian-Eulerian model was developed and experimentally validated for hydrodynamics in two steps: first against pressure-drop data from a cylindrical fluidised bed, and then against particle-velocity measurements from a transparent moving packed bed receiver. Because the transparent receiver could not withstand CSP-relevant temperatures, direct high-temperature thermal validation was not performed, and the thermal behaviour was instead predicted using the hydrodynamically validated framework. The simulations used the Syamlal-O’Brien drag model, kinetic theory granular closures, and the Gunn correlation for gas-particle heat transfer. Under a fixed wall temperature of 773.15 K, the apparent wall-to-particle heat transfer coefficient was approximately 2.7 kW/(m2·K) for alumina and 1.3 kW/(m2·K) for silica sand. The higher predicted performance of alumina is attributed to its higher density, heat capacity, and effective packed-bed thermal conductivity. The results indicate that gravity-driven dense-phase receivers are a promising configuration for indirect particle heating, while future work should include direct high-temperature validation under realistic solar flux conditions.