Infrared-Reflective Coating on Fused Silica for a Solar High-Temperature Receiver
Röger, Marc and Rickers, Christoph and Uhlig, Ralf and Neumann, Frank and Polenzky, Christina
Infrared-Reflective Coating on Fused Silica for a Solar High-Temperature Receiver.
In: Proceedings of Energy Sustainability 2007.
ES 2007, 2007-06-27 - 2007-06-30, Long Beach, CA (USA).
In concentrating solar power, high-temperature solar receivers can provide heat to highly efficient cycles for electricity or chemical production. Excessive heating of the fused-silica window and the resulting recrystallization are major problems of high-temperature receivers using windows. Excessive window temperatures can be avoided by applying an infrared-reflective solar-transparent coating on the fused-silica window inside. Both glass temperatures and receiver losses can be reduced. An ideal coating reflects part of the thermal spectrum (λ>2.5 µm) of the hot absorber (1100°C) back onto it without reducing solar transmittance. The examined transparent conductive oxides (TCO) involve a high solar absorptance, inhibiting their use in high-concentration solar systems. Although conventional dielectric interference filters have a low solar absorption, the reflection of solar radiation which comes from various directions is too high. It was found that only rugate filters fulfill the requirements for operation under high-flux solar radiation with different incident angles. A thermodynamic qualification simulation of the rugate coating on a window of a flat-plate receiver showed a reduction of almost 175 K in mean window temperature and 11% in receiver losses compared to an uncoated window. Finally, a first 25-µm thick rugate filter was manufactured and optically characterized. The issue of this paper is to share the work done on the choice of filter type, filter design, thermodynamic evaluation, and deposition experiments.
|Document Type:||Conference or Workshop Item (Speech, Paper)|
|Title:||Infrared-Reflective Coating on Fused Silica for a Solar High-Temperature Receiver|
|Authors||Institution or Email of Authors|
|Rickers, Christoph||Fraunhofer-Institut für Schicht- und Oberflächentechnik IST, Braunschweig|
|Neumann, Frank||Fraunhofer-Institut für Schicht- und Oberflächentechnik IST, Braunschweig|
|Polenzky, Christina||Fraunhofer-Institut für Schicht- und Oberflächentechnik IST, Braunschweig|
|Journal or Publication Title:||Proceedings of Energy Sustainability 2007|
|In ISI Web of Science:||Yes|
|Keywords:||Infrared-Reflective Coating, IRR, Solar Receiver, High Temperature, Window, Rugate Filter,|
|Event Title:||ES 2007|
|Event Location:||Long Beach, CA (USA)|
|Event Type:||international Conference|
|Event Dates:||2007-06-27 - 2007-06-30|
|HGF - Research field:||Energy|
|HGF - Program:||Renewable Energies|
|HGF - Program Themes:||E SF - Solar research (old)|
|DLR - Research area:||Energy|
|DLR - Program:||E SF - Solar research|
|DLR - Research theme (Project):||E - Solare Hochtemperatursysteme (old)|
|Institutes and Institutions:||Institute of Technical Thermodynamics > Solar Research|
|Deposited On:||11 Jan 2008|
|Last Modified:||12 Dec 2013 20:27|
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