Journal article
Optical analysis of a semi-transparent packed bed of spheres for next-generation volumetric solar receivers
Energy, Vol.252, pp.1-13
01/08/2022
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Source: InCites
Abstract
Volumetric solar absorbers are attractive for high-temperature concentrating solar applications because they—theoretically—have lower re-radiation losses than surface absorbers since concentrated radiation penetrates their volume. In practice, however, the incident radiation is predominantly absorbed in the top/frontal surfaces of porous and distributed absorber materials. Another challenge with high-temperature absorbers, generally, is the risk of creating hot spots resulting from a non-uniform temperature distribution. To overcome these limitations, this study reports on a semi-transparent absorber design, enabling the peak temperature to occur within the internal volume. Eight different ‘constant-transmittance’ and ‘variable-transmittance’ combinations of transparent/semi-transparent/opaque spheres were packed into a cylindrical cavity and exposed to a solar simulator for a layer-by-layer transmission test. A 3-D ray-tracing model was also developed to further elucidate the relative optical absorption of the cavity walls and spheres. An optimal variable-transmittance design enabled ∼40% of the rays to penetrate to >70% of the absorber's depth, and ∼56% of the total rays were absorbed within the inner volume. Therefore, the optimal design yields uniform absorption, potentially leading to a uniform temperature distribution and a minimisation of thermal emission losses. This study provides the first experimental proof that a semi-transparent packed bed can significantly outperform an opaque design.
Details
- Title
- Optical analysis of a semi-transparent packed bed of spheres for next-generation volumetric solar receivers
- Creators
- Mohammadreza Sedighi - Southern Cross UniversityRicardo Vasquez Padilla - Southern Cross UniversityAndrew Rose - Southern Cross UniversityRobert A Taylor - University of New South Wales
- Publication Details
- Energy, Vol.252, pp.1-13
- Publisher
- Elsevier Ltd
- Identifiers
- 991013019234302368
- Copyright
- © 2022 Elsevier Ltd. All rights reserved.
- Academic Unit
- Faculty of Science and Engineering; Engineering; Office of the Vice Chancellor
- Language
- English
- Resource Type
- Journal article