Design and fabrication of thermally stable HfMoN/HfON/Al2O3 tandem absorber for solar thermal power generation applications

Selvakumar, N and Manikandanath, NT and Biswas, A and Barshilia, Harish C Design and fabrication of thermally stable HfMoN/HfON/Al2O3 tandem absorber for solar thermal power generation applications. Solar Energy Materials and Solar Cells. ISSN 0927-0248 (In Press)

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Abstract

A new HfMoN(H)/HfMoN(L)/HfON/Al2O3 tandem absorber is designed and developed for high temperature solar thermal applications. The first absorber layer, HfMoN(H) is designed to have higher metallic content than the second HfMoN(L) layer. By varying the nitrogen flow rate, two different HfMoN layers with different refractive indices were deposited on SS substrates. The optical constants (n and k) measured using spectroscopic ellipsometry showed that HfMoN(H) and HfMoN(L) are the main absorber layers and HfON/Al2O3 acts as a double layer antireflection coating. The gradual decrease in the refractive indices from the substrate to the top resulted in increase in the absorptance, which was confirmed by the ellipsometric mesurements. The optimized four layer tandem absorber exhibited high absorptance ( = 0.94-0.95) and low thermal emittance (82C = 0.13-0.14). The four layer tandem absorber was thermally stable up to 600°C for 450 hrs and 650°C for 100 hrs in vacuum. Whereas, coatings heat-treated in air were thermally stable up to 475C for 34 hrs.

Item Type: Article
Subjects: RENEWABLE ENERGY > Solar Energy
Depositing User: Mr N Selvakumar
Date Deposited: 12 Apr 2012 10:33
Last Modified: 17 Aug 2015 10:08
URI: http://nal-ir.nal.res.in/id/eprint/10423

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