Spectrally selective solar absorber coating
The aim of the patent is to make available spectrally selective solar absorber coatings with photo-thermal performance and stability increased compared to those currently on the market for the receivers of thermal and thermodynamic solar systems. To meet both needs, the patent proposes to use a multilayer structure in which the metal is alternated with layers having the function of stabilizing the metal itself as an infrared (IR) reflector instead of the single metal layer.
The new generation receiver tubes of thermodynamic solar systems must operate, with high photo-thermal performance, at temperatures as high as possible to increase the efficiency of the thermodynamic energy conversion cycle and to create a compact and more efficient direct storage system. heat able to guarantee continuity of service even at night or with cloudy skies. To improve the performance of the solar coating at a temperature of 550 ° C or higher, the patent proposes to use metals with the lowest heat losses, such as copper, aluminum, silver and gold, as an IR reflector, inserting them in a multilayer structure alternating with materials capable of stabilizing these metals at high temperatures. More generally, the proposed multilayer structure offers the advantage of making any metal more stable at a fixed operating temperature, ensuring the coating that adopts this structure produces more efficient thermal energy over time. Finally, if we consider the use of the receiver tube in the air, the multilayer structure can improve the stability of the coating up to a maximum temperature of at least 300 ° C if it is made by alternating layers of metal with layers of materials with the function of both stabilizing the metal is a barrier against the diffusion of atmospheric oxidizing agents.
- Solar coating for a receiver of a thermodynamic solar system with operating temperature up to at least 550 ° C in vacuum;
- Solar coating for a receiver of a solar thermal system with an operating temperature up to at least 300 ° C in air.
- Improving the photo-thermal performance of a solar coating at higher operating temperatures;
- Increase the stability of a solar coating;
- Make available a versatile solar coating for effective use in vacuum up to at least 550 ° C and in air up to at least 300 ° C.