Solar selective absorbers based on two-dimensional W surface gratings with submicron periods for high-temperature photothermal conversion

摘要

Spectral properties and thermal stability of two-dimensional (2D) W surface gratings with submicron periodicity are investigated to develop solar selective absorbers for high-temperature applications. Numerical calculations based on the rigorous coupled-wave analysis technique have been performed for simulating the spectral properties of W gratings. The results indicate that the gratings with microcavities have a good spectral selectivity suited for high-temperature applications, while the gratings with micropyramids realize a high solar absorptance over 0.92. 2D surface gratings with submicron holes have been fabricated on W substrates by the fast atom beam etching with highly ordered porous alumina masks. They have shown good spectral selectivity and sufficient thermal stability at 1170 K under a vacuum atmosphere. The observed absorption band is considered to originate from the standing wave resonance between the electromagnetic fields and the standing wave mode generated inside the holes. (C) 2002 Elsevier B.V. All rights reserved. [References: 25]