Abstract: The tubular radiation absorbing device (1) for solar thermal applications includes a central tube (3) made of chromium steel, particularly stainless steel; a glass tubular jacket (2) surrounding the central tube so as to form a ring-shaped space (6); and a barrier coating (4) on at least an interior side of the central tube (3), which is substantially impermeable to hydrogen and contains chromium oxide. The barrier coating (4) is provided by a process in which the central tube (3) is treated with steam containing free hydrogen at a temperature of 500° C. to 700° C.

Abstract: The invention relates to a solar absorber comprising an absorber body (10) provided with an absorption layer (17) on the side thereof on which the radiation concentrated by a concentrator is incident, and an absorption layer (18) on the opposite side. The absorption layer on the side facing the concentrator has a higher boundary wavelength than the opposing absorption layer. In this way, in the region of higher irradiance, the limit of the radiation emission of the absorber body is shifted to longer wavelengths such that both sides of the absorber body are operated with the respectively highest possible directivity.

Abstract: The invention relates to a solar collector comprising an absorber tube (13) supported by supports. Radiation-per-meable cladding tubes (15) are located between the supports and surround the absorber tube (13). Compensation pieces (17) are provided between the cladding tubes (15) due to the fact that the absorber tube (13) and the cladding tubes (15) have different expansion behaviors. In order to also capture radiation that strikes the connection area (50), at least one mirror collar (20) is provided that reflects the solar radiation into the area of the active absorber tube surface. This mirror collar (20) is capable of reflecting the concentrated solar radiation coming from different directions from the parabolic mirrors even at different solar angles of incidence upon the active absorber surface.

Abstract: A tubular radiation absorbing device (1) designed for a solar heating application is described. The tubular radiation absorbing device has a metal central tube (3) and a glass tubular jacket (2) surrounding the central tube (3). A folding bellows (11) is connected between the central tube (3) and the tubular jacket (2), so that the tubular jacket and the central tube are movable relative to each other. A connecting element (20) connects an inner end of the folding bellows (11) with the central tube (3) and extends from the inner end of the folding bellows (11) through an inner annular space (30) between the folding bellows (11) and the central tube (3). The connecting element includes at least a part of a hydrogen window (50). A getter (6) is arranged in an outer annular space (33) between the folding bellows (11) and the tubular jacket (2).

Abstract: The absorber pipe (1), especially for a parabolic collector for a solar heat collecting apparatus, is described. The absorber pipe (1) includes central metal pipe (3), a glass sleeve tube (2) surrounding the nine so that an annular space (4) is formed between them and an expansion compensating device connecting the central metal nine and a glass-metal transitional element (5) on a free end of the sleeve tube (2). The expansion compensation device (10) connects the metal pipe and sleeve tube, so that they can slide relative to each other, and includes folding bellows (11) for that purpose. Furthermore it also includes a connecting element (15), which has either a cylindrical or a conical section (17,18,18?) and which connects an interior end of the folding bellows with the metal pipe.

Abstract: An absorber with a radiation-selective absorber coating is described, which includes a metal substrate, a diffusion-blocking layer, a metallic reflective layer, a cermet layer and an anti-reflective layer. The diffusion-blocking layer is an oxide layer, which includes oxidized components of the metal substrate. The method for making this sort of absorber includes tempering the surface of the substrate, on which the absorber coating is provided, in air in an oven at a temperature of 400 to 600° C. for 0.5 to 2 hours.

Abstract: The method of making a vacuum tube collector or X-ray tube, which includes a matching glass-metal joint, includes providing a glass tube (1) made of a glass with a composition, in percent by weight on the basis of oxide content, consisting of B2O3, 8-11.5; Al2O3, 5-9; Na2O, 5-9; K2O, 0-5; CaO, 0.4-1.5; balance, SiO2; and bonding, preferably fusing or melting, an end portion of the glass tube (1) with a metal part (2) in order to bond or attach the glass tube to the metal part, thus forming a long-lasting glass-metal joint. The method of making the glass-metal joint is performed without using intermediary glass compositions of varying thermal conductivities. In the case of the vacuum tube collector the method can provide the basis for an automated manufacture of the vacuum tube collector.

Abstract: The parabolic trough collector includes a single-axis parabolic mirror (1) and a receiver tube (2) arranged at the focal point (F) of the parabolic mirror (1). The receiver tube (2) includes an absorber tube (4) and an outer tubular glass jacket (3) around it. To compensate for focusing errors in the parabolic collector and thus to reduce associated geometric optical losses, the tubular jacket (3) is provided with structural elements (9a, 9b, 9c, 9d), which focus the sunlight on the absorber tube (4) arranged in the tubular jacket (3) by reflection and/or refraction. The receiver tube (2) is preferably arranged relative to the parabolic mirror (1), so that its center is displaced from the focal point (F) in the direction of the mirror by a distance equal to half the spacing between the tubular jacket (3) and the absorber tube (4).

Abstract: The absorber pipe (1), especially for a parabolic collector for a solar heat collecting apparatus, is described. The absorber pipe (1) has a central metal pipe (3) and a glass sleeve tube (2). An expansion compensation device (10) is provided, which is arranged at least partially in an annular space (4) between the metal pipe (3) and a glass-metal transitional element (5), which is attached to the sleeve tube (2). The expansion compensation device (10) can have a folding bellows (11). Furthermore a connecting element (15) is provided, which has either a cylindrical or a conical section (17, 18, 18″).