The present invention relates to a solar selective coating for a metal substrate comprising at least one absorber layer and at least one semi-absorber layer selected from the structures of AlTiN and AlTiSiN. In preferred embodiments, the solar selective coating according to the present invention is a double layer coating with AlTiN-AlTiN or AlTiSiN-AlTiSiN formation. The process for producing the coating includes a step of treatment of the metal substrate with a reactive magnetron sputtering system.

The present disclosure provides a solution-processed selective solar absorption coating and a process for the preparation thereof.

The present disclosure provides a solution-processed selective solar absorption coating and a process for the preparation thereof.

A passive cooling article is disposed on a substrate to cool the substrate. The article includes an outer layer having a high absorbance in the atmospheric window region of the electromagnetic spectrum and having a high transmittance in the solar region of the spectrum. The article also includes a reflector having a high reflectivity in the solar region of the spectrum. At least one of the outer layer and the reflector includes a fluoropolymer. Micro-sized particles or surface structures may be disposed in or on the outer layer or the reflector to improve absorbance. A metallic layer may be disposed between the fluoropolymer and the substrate to be cooled.

An exemplary solar selective coating can be provided to be deposited on a substrate. The exemplary solar selective coating can comprise an adhesion layer, an absorber stack comprising at least one absorber layer, and an antireflection stack which can comprise at least one antireflection layer, e.g., all provided in a sandwich configuration. The sandwich configuration can provide the adhesion layer deposited onto the substrate, the absorber stack deposited on the adhesion layer, and the antireflection stack deposited on the absorber stack. The adhesion layer can comprise a metallic layer comprising molybdenum and titanium.

A method for coating by thermal spraying a substrate for solar applications with a temperature-resistant and high-absorbance ceramic micro-structured coating includes the following steps: preparing a powder mixture including ceramic microparticles powder and polyester microballs powder, a percentage of the polyester microballs in the powder mixture being between 10 and 30% w/w; spraying the powder mixture onto the substrate by a thermal spray process in order to apply a coating layer on the substrate; and heating the substrate having the coating layer to a temperature of at least 400 C. so as to evaporate the microballs of polyester from the coating layer, leaving porosities at a place of the polyester microballs. Parameters of the spraying step and particle size are chosen so that the coating layer is applied in a thickness of between 50 and 150 microns.

A method for coating by thermal spraying a substrate for solar applications with a temperature-resistant and high-absorbance ceramic micro-structured coating includes the following steps: preparing a powder mixture including ceramic microparticles powder and polyester microballs powder, a percentage of the polyester microballs in the powder mixture being between 10 and 30% w/w; spraying the powder mixture onto the substrate by a thermal spray process in order to apply a coating layer on the substrate; and heating the substrate having the coating layer to a temperature of at least 400 C. so as to evaporate the microballs of polyester from the coating layer, leaving porosities at a place of the polyester microballs. Parameters of the spraying step and particle size are chosen so that the coating layer is applied in a thickness of between 50 and 150 microns.

Disclosed are methods and functional elements for enhanced thermal management of predominantly enclosed spaces. In particular, the invention enables the construction of buildings with reduced power requirements for heating and/or air-conditioning systems since under certain conditions less energy for heating or cooling is required to maintain, within certain boundaries, desirable temperatures inside such buildings, habitats, or other enclosed spaces.

In some instances the invention is in part based on dynamically changing functional elements with variable properties, or effective properties, in terms of their electromagnetic radiative behavior and/or their thermal energy storage properties, or the spatial distribution of the stored thermal energy, which permits the application of methods and algorithms to control the overall thermal behavior of the entire structure in such a way that desired levels of inside temperature can be reached with reduced consumption of external energy (typically electricity, gas, oil, or coal).

In some instances no conventional heating of cooling is required at all, whereas in other instances the expenditure of external energy for conventional heating or cooling is reduced. In some instances the invention enables the reduction of the time to reach desired temperatures inside such buildings, habitats, or other predominantly enclosed spaces.

Method of manufacturing a spectrally selective surface. The method comprises cleaning an outside of a tubular substrate, e.g. by sonicating in acetone, polishing the cleaned outside, and depositing a CoCr coating on the polished outside, i.e. the tubular substrate's outside. The CoCr coating comprises Co(II) compounds and Cr(III) compounds but no Cr(VI) compounds. By applying a DES electrolyte Cr(III)-ions may be solved in the electrolyte such that a receiver tube arranged in the electrolyte may become coated with a selective CoCr coating from Cr(III)-ions, where the optical characteristics regarding absorptance and emittance for the resulting receiver tube are comparable or surpasses traditional black chrome. Thereby use of harmful hexavalent chrome could be avoided, which may achieve more healthy and environmental friendly conditions. Particularly, no harmful Cr(VI)-ions or rest substances comprising them will contaminate ambient air or need to be handled or disposed.

Method of manufacturing a spectrally selective surface. The method comprises cleaning an outside of a tubular substrate, e.g. by sonicating in acetone, polishing the cleaned outside, and depositing a CoCr coating on the polished outside, i.e. the tubular substrate's outside. The CoCr coating comprises Co(II) compounds and Cr(III) compounds but no Cr(VI) compounds. By applying a DES electrolyte Cr(III)-ions may be solved in the electrolyte such that a receiver tube arranged in the electrolyte may become coated with a selective CoCr coating from Cr(III)-ions, where the optical characteristics regarding absorptance and emittance for the resulting receiver tube are comparable or surpasses traditional black chrome. Thereby use of harmful hexavalent chrome could be avoided, which may achieve more healthy and environmental friendly conditions. Particularly, no harmful Cr(VI)-ions or rest substances comprising them will contaminate ambient air or need to be handled or disposed.