PERFORMANCE CHARACTERIZATION OF ORDERED POROUS VOLUMETRIC SOLAR RECEIVERS

Document Type

Conference Proceeding

Publication Date

2022

Department

Department of Mechanical Engineering-Engineering Mechanics

Abstract

Ordered porous structures are deemed promising candidates for high concentrated volumetric solar receivers, but the effect of pore size on their coupled optical and thermal characteristics has not been fully studied. Here, a 3D pore-level Monte Carlo ray-tracing model coupled with transport equations is developed to examine the conjugate radiative, convective, and conductive heat transfer mechanisms of ordered porous structures. Coupled optical-thermal performances and solar-to-thermal conversion efficiencies of both uniform and non-uniform ordered volumetric receivers with small-, medium-, large-, and gradient-pore-sizes are investigated. It was found that the solar-to-thermal conversion efficiency might be thermally or optically limited depending on the thermo-hydraulic characteristics of the working fluid. At high air flow rates, the conversion efficiency is optically limited. This results in high conversion efficiencies of the gradient-pore-size volumetric receiver due to enhanced thermal (i.e., convective effects) and optical characteristics (i.e., low optical thickness and deep light-trapping effect) at high flow rates. On the other hand, at low air flow rates, the results show that the conversion efficiency is thermally limited as is the case with the large-pore-size volumetric receiver.

Publication Title

Proceedings of the Thermal and Fluids Engineering Summer Conference

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