Reduced-Order Modeling of Indirect Fluidized-Bed Particle Receivers with Axial Dispersion

Oxide particles present a heat transfer and thermal energy storage (TES) media for next-generation concentrating solar power (CSP) plants where the high-temperature particle TES can provide dispatchable solar power 1. Transferring heat to flowing particles can be a challenge and bubbling fluidization is a promising method for increased heat transfer between the oxide particles and confining walls. Using experimentally calibrated correlations for particle-wall heat transfer coefficients 2, this study explores in a quasi-1D model of a narrow-channel counterflow fluidized bed how the high heat transfer coefficients from bubbling fluidization enable cavity-based indirect particle receivers. Particle-wall heat transfer coefficients exceeding 800 W m-2 K-1 support angled solar fluxes > 200 kW m-2 from high normal fluxes > 1200 kW m-2 with wall temperatures < 900 oC. Parametric studies identify how gas flows, solar fluxes, and receiver heights impact receiver solar efficiency for a CSP plant. These modeling studies provide a basis for the development of an indirect narrow-channel fluidized particle receiver that has the potential to operate at normal solar fluxes over 1000 kW m-2 and solar efficiencies above 85%.