An improved multilayer solar selective coating for high temperature solar thermal applications and a process for the preparation thereof

Indian (2014) An improved multilayer solar selective coating for high temperature solar thermal applications and a process for the preparation thereof. 2226/DEL/2014.

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Abstract

Today there is great challenge to develop solar selecting coatings that have high solar absorptance and low thermal emittance for temperatures greater than 400°C.The present invention provides a multilayer solar selective coating on metallic and non-metallic substrates, more particularly on stainless steel 304 substrates, suitable for high temperature solar thermal power applications. The optimized solar selective coating of the present invention on stainless steel substrate exhibits absorptance of 0.954 and emittance of 0.07. All the layers of the solar selective coating of the present invention have been deposited using the sputtering process. The multilayer solar selective coating of the present invention consists of (1) tungsten (W) layer (2) titanium aluminum nitride (TiAlN) (3) titanium aluminum silicon nitride (TiAlSiN) (4) titanium aluminumsilicon oxy-nitride (TiAlSiON) and (5) titanium aluminumsihcon oxide (TiAlSiO). The first layer (W) acts an infrared reflector, the second layer (TiAlN), the third layer (TiAISiN) and the fourth layer (TiAlSiON) act as the absorber layer and the fifth layer (TiAlSiO) acts as the anti-reflection layer. The anti-reflection layer is treated with Ar+02 plasma to improve the thermal and chemical stability of the overall solar selective coating. The W layer was deposited using a balanced magnetron sputtering system and the absorber layers and the anti-reflection layers were deposited using a four cathode reactive pulsed direct current magnetron sputtering system. The solar selectivity ration of the solar selective coating of the present invention on stainless steel substrate is of the order of 9-14 and it and displays thermal stability is vacuum upto 600°C for lOOOhrs under cyclic heating conditions. The solar selective coating of the present invention qualified 100 thermal shock treatments at 375°C in air. The present invention provides a high-temperature solar selective coating which exhibits average emittance of 0.10 at 400°C on stainless steel substrate in the wavelength range of 2.5-25|im, thus is suitable for applications in concentrating collectors like evacuated receiver tubes for solar thermal power generation. 25

Item Type: Patent
Subjects: RENEWABLE ENERGY > Solar Energy
Depositing User: Dr. Harish C. Barshilia
Date Deposited: 20 Jul 2018 10:41
Last Modified: 20 Jul 2018 10:41
URI: http://nal-ir.nal.res.in/id/eprint/12722

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