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Angle resolved specular reflectance measured with VLABS

 
: Heimsath, A.; Schmid, T.; Nitz, P.

:
Postprint (PDF; )

Energy Procedia 69 (2015), pp.1895-1903
ISSN: 1876-6102
International Conference on Concentrating Solar Power and Chemical Energy Systems (SolarPACES) <20, 2014, Beijing>
English
Journal Article, Conference Paper, Electronic Publication
Fraunhofer ISE ()
Solarthermie und Optik; Solarthermie; Solarthermische Kraftwerke; optics; reflector; resolved scattering; reflectance; angle

Abstract
In the process of improving the performance of concentrating solar collectors a variety of reflector materials are undergoing development. To allow comparable performance predictions, precise and replicable measuring methods are needed. In this paper we propose a measurement method and set-up (VLABS: very-low-angle beam spread) to determine the specular reflectance for variable angular acceptance. Our measurement set-up and method VLABS is advanced in measurement accuracy and speed, it gives as a result the specular reflectance for variable acceptance angles with an angular resolution of 0.03 mrad. We show exemplary results for a glass and an aluminum reflector and discuss the impact of acceptance angles up to 33 mrad on measured reflectance values at different wavelengths.

: http://publica.fraunhofer.de/documents/N-366837.html