There is provided a heat resistant ferritic steel including a base material including, by mass percent, C: 0.01 to 0.3%, Si: 0.01 to 2%, Mn: 0.01 to 2%, P: at most 0.10%, 5: at most 0.03%, Cr: 7.5 to 14.0%, sol.Al: at most 0.3%, and N: 0.005 to 0.15%, the balance being Fe and impurities, and an oxide film that is formed on the base material and contains 25 to 97% of Fe and 3 to 75% of Cr. This heat resistant ferritic steel is excellent in photoselective absorptivity and oxidation resistance.

Techniques, systems, devices and materials are disclosed for spectrally selective coatings for optical surfaces having high solar absorptivity, low infrared emissivity, and strong durability at elevated temperatures. In one aspect, a spectrally selective coating includes a substrate formed of a light absorbing material, and a composite material formed over the substrate and including nanoparticles dispersed in a dielectric material, in which the composite material forms a coating capable of absorbing solar energy in a selected spectrum and reflecting the solar energy in another selected spectrum.

The present invention includes a heat exchanger reactive to external and internal temperatures for carrying a working fluid, including two pairs of nested pipes; each pair including one pipe with a channel portion and a stress relief portion and a second pipe with just a channel portion, one of said pipes enclosing the other with an interference fit and both pipes having different coefficients of thermal expansion. The first pair of pipes positioned co-axially with and encompassing the second pair. A fluid is positioned in the space defined by the inner surface of outer pair of pipes and the outer surface of inner pair of pipes. The two pipe pairs have positions responsive to the internal and external temperatures in which the space defined by pipe pairs is either minimized or maximized by expansion and contraction of the pipe pairs caused by differences in coefficients of thermal expansion.

The present invention includes a heat exchanger reactive to external and internal temperatures for carrying a working fluid, including two pairs of nested pipes; each pair including one pipe with a channel portion and a stress relief portion and a second pipe with just a channel portion, one of said pipes enclosing the other with an interference fit and both pipes having different coefficients of thermal expansion. The first pair of pipes positioned co-axially with and encompassing the second pair. A fluid is positioned in the space defined by the inner surface of outer pair of pipes and the outer surface of inner pair of pipes. The two pipe pairs have positions responsive to the internal and external temperatures in which the space defined by pipe pairs is either minimized or maximized by expansion and contraction of the pipe pairs caused by differences in coefficients of thermal expansion.

When a roof tile provided with a hole is manufactured, first a non-cured composition 11 is fed between two facing mold surfaces 13b and 15b of two mold halves 13 and 15 after which the two mold halves are brought together. The mold surface 13b of one of the two mold halves 13 is provided with a bulge 17 which has a thickness 19 that is smaller than the distance 21 between the two mold surfaces 13b and 15b at the location of this bulge in the state of the mold halves brought together. As a result, the roof tile obtains a thin part 23 at the location of this bulge 17. After the pressing operation the two mold halves 13 and 15 are taken apart and the composition 11 is cured. Once the roof tile 1 has cured, the thin part 23 is broken away from the roof tile and in this manner the hole 5 in the roof tile is formed.

When a roof tile provided with a hole is manufactured, first a non-cured composition 11 is fed between two facing mold surfaces 13b and 15b of two mold halves 13 and 15 after which the two mold halves are brought together. The mold surface 13b of one of the two mold halves 13 is provided with a bulge 17 which has a thickness 19 that is smaller than the distance 21 between the two mold surfaces 13b and 15b at the location of this bulge in the state of the mold halves brought together. As a result, the roof tile obtains a thin part 23 at the location of this bulge 17. After the pressing operation the two mold halves 13 and 15 are taken apart and the composition 11 is cured. Once the roof tile 1 has cured, the thin part 23 is broken away from the roof tile and in this manner the hole 5 in the roof tile is formed.

A solar thermal collector and an accessory structure of a building are provided. The solar thermal collector includes at least one heat absorbing plate and at least one heat insulating plate. Each of the heat absorbing plate includes at least one first slab and first engaging parts connected with the first slab. Each of the heat insulating plate includes at least one second slab and second engaging parts connected with the second slab. The first engaging parts are respectively engaged with the second engaging parts, and a gap is maintained between the first slab and the second slab to define a heat collecting channel, through which a heat transfer medium flows between the heat absorbing plate and the heat insulating plate. A heat conductivity of the heat absorbing plate is at least 30 times greater than a heat conductivity of the heat insulating plate.

A solar thermal collector and an accessory structure of a building are provided. The solar thermal collector includes at least one heat absorbing plate and at least one heat insulating plate. Each of the heat absorbing plate includes at least one first slab and first engaging parts connected with the first slab. Each of the heat insulating plate includes at least one second slab and second engaging parts connected with the second slab. The first engaging parts are respectively engaged with the second engaging parts, and a gap is maintained between the first slab and the second slab to define a heat collecting channel, through which a heat transfer medium flows between the heat absorbing plate and the heat insulating plate. A heat conductivity of the heat absorbing plate is at least 30 times greater than a heat conductivity of the heat insulating plate.

A component includes a substrate and a coating system. The coating system includes a base layer that includes at least one of a (M1)AX phase and a (M2)CrX composition. The coating system also includes a top layer that includes a black pigment embedded in a matrix. The matrix is one of a metal-based matrix and a ceramic-based matrix.

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.