Solar particle receivers (SPRs) are pursued as a promising technology for conversion of concentrated solar radiation for power generation and chemical processing. Particle receivers use absorbing particles as heat transfer and thermal energy storage media. Falling particles form a particle curtain inside a receiver to absorb solar irradiation, and can attain temperatures above 1000°C. A thorough understanding of heat transfer addressing radiative heat transfer in polydisperse particles is crucial to advance the solar particle receiver technology. A complete heat transfer model involving hydrodynamics of particleâgas multi-phase flows, radiation in the particle phase, interfacial convection, and conduction in the gas phase is required to understand the physical problems encountered in SPRs.
We present simulations of particleâgas two-phase flows using the multi-phase particle-in-cell method. The method allows for capturing high-fidelity solidâgas flow characteristics with increased computational efficiency by combing the advantages of both Eulerian and Lagrangian methods. Radiative transfer in polydisperse particles is investigated using a novel radiative transfer model. The radiative transfer model considers polydisperse particles as a multi-component system and is implemented using the Monte Carlo ray-tracing method. A three-dimensional computational fluid dynamics model is developed for directly-irradiated high-temperature particleâgas flows laden with polydisperse particles by coupling particleâgas hydrodynamics of particleâgas flows, radiative heat transfer in non-grey absorbing, emitting and anisotropically-scattering multi-component media, conduction in the gas phase, and interfacial convective heat transfer. The computational model is employed to study thermal performance of a free-falling particle receiver.
