Performance analysis of a volumetric receiver composed of packed shaped particles with spectrally dependent emissivity

The volumetric receiver is a key component in the concentrated power plant. In this work, we propose a novel porous medium structure for solar volumetric receivers by accounting for both high heat transfer features and low pressure drop, which is composed of packed strut cross shaped particles whose surface radiative property is spectrally dependent. A local thermal non-equilibrium model is established, and the effective parameters of the porous media are obtained from the Kelvin model. The effects of the pore size, porosity, wavelength related emissivity and Heywood circularity factor of the strut cross section on the heat transfer and flow in the receiver are investigated. Results show that the radiation loss of the receiver mainly depends on the first five representative elementary volumes. The efficiency increases with the porosity and Heywood circularity factor. By decreasing the infrared emissivity of the receiver, the efficiency increases about 3% compared to the receiver with constant emissivity. Finally, a hybrid dual layer receiver is introduced to improve the heat transfer and flow performance, and the efficiency enhancement of up to 4% can be achieved.