Radiation collector

• US 20090272375A1
• Filed: 09/28/2007
• Published: 11/05/2009
• Est. Priority Date: 09/27/2006
• Status: Active Grant

• Current Assignee: Airlight Energy IP SA
• Original Assignee: Airlight Energy IP SA
• Inventors: Pedretti, Andrea
• Granted Patent: US 8,469,023 B2
• Time in Patent Office: Days
• US Class Current: 126/696
• CPC Class Codes: F24S 20/20 Solar heat collectors for receiving concentrated solar energy, e.g. receivers for solar power plants
• CPC Class Codes: F24S 23/715 flexible
• CPC Class Codes: F24S 23/745 flexible
• CPC Class Codes: F24S 23/81 flexible F24S23/715, F24S23/745 take precedence
• CPC Class Codes: Y02E 10/40 Solar thermal energy, e.g. solar towers
• CPC Class Codes: Y02E 10/46 Conversion of thermal power into mechanical power, e.g. Rankine, Stirling or solar thermal engines

Abstract

Disclosed is a radiation collector comprising a pressure cell which is subdivided into a first pressure chamber and a second pressure chamber by means of the concentrator. The small pressure difference between the pressure chambers keeps the concentrator operational in a beam-concentrating form and reduces the wear on the reflective layer of the concentrator. The radiation collector further comprises adequately designed means for establishing the desired pressure in the respective pressure chamber, said means making it possible to compensate changes of the pressure chamber volume resulting from wind load, for example.

Claims

1. Radiation collector with a pressure cell which is at least partially formed from a flexible membrane and has a transparent region for radiation to be reflected, characterized by a concentrator which is arranged securely in the pressure cell, has a flexible membrane, has a side which faces the transparent region and reflects the radiation and a side which faces away from the radiation, and divides the pressure cell into a 1st pressure chamber and a 2nd pressure chamber, and wherein means are provided to operationally generate and maintain pressures within a predefined range when the volume of one or both pressure chambers is altered by external influences during operation.

2. Radiation collector according to claim 1, wherein the means for generating pressure in the pressure chambers have an overflow region, which connects the 1st and 2nd pressure chambers with each other, for fluid which is present in the pressure chambers.

3. Radiation collector according to claim 1 or 2, wherein the radiation collector with a pressure cell which is at least partially formed from a flexible membrane has a transparent region for radiation to be concentrated, and the reflector which is arranged securely in the pressure cell as the concentrator is configured with a flexible, fluid-tight membrane, which has a side which faces the transparent region and reflects the radiation and a side which faces away from the radiation and is held pneumatically in the operating position which concentrates the radiation by means of the pressure prevailing on the reflective side, wherein the concentrator divides the pressure cell into the 1st pressure chamber with higher operating pressure and the 2nd pressure chamber with lower operating pressure, and wherein means for generating pressure in the pressure chambers are further configured to operationally generate and maintain pressures of predefined difference when the volume of one or both pressure chambers is altered by external influences during operation.

4. Radiation collector according to claim 3, wherein the predefined pressure difference is less than 0.5 mbar, preferably in a range from 0.05 to 0.2 mbar, and particularly preferably in the range from 0.05 to 0.1 mbar.

5. Radiation collector according to one of claims 3 or 4, wherein the operating pressure in the 1st pressure chamber is in a range from 1 to 5 mbar, preferably 2 to 5 mbar and particularly preferably in a range from 3 to 4 mbar.

6. Radiation collector according to one of claims 3 to 5, wherein the pressure cell has a contour which is lens-shaped with a round outline and consists of an upper and a lower in each case flexible membrane face, the upper membrane face of which is configured to be transparent for radiation to be concentrated, wherein the concentrator is arranged between the upper and lower membrane faces such that it runs as far as the edge zone in such a manner that during operation the first pressure chamber has a convex shape and the second pressure chamber has a concave shape, and wherein the pressure cell is suspended along its edge region on a frame.

7. Well or trough collector according to one of claims 3 to 5, wherein the pressure cell has a contour which is cushion-shaped with a rectangular outline and consists of an upper and a lower in each case flexible membrane face, the upper membrane face of which is configured to be transparent for radiation to be concentrated, wherein the concentrator is arranged between the upper and lower membrane faces such that it runs as far as the edge zone in such a manner that during operation the first pressure chamber has a convex shape and the second pressure chamber has a concave shape, and wherein the pressure cell is suspended along its edge region on a frame.

8. Radiation collector according to one of claims 3 to 7, in which the pressure chambers are filled with a fluid, preferably air, during operation, wherein the means for generating the predefined pressure difference have a first fluid duct which opens into the first pressure chamber and a second fluid duct which opens into the second pressure chamber, through which ducts fluid can flow in both directions in order to maintain the setpoint operating pressure, wherein a fluid pump is provided which is preferably configured as a fan and can be operated in such a manner that the respective setpoint operating pressure prevails in the associated pressure chamber.

9. Radiation collector according to claim 8, wherein the two pressure chambers are connected to each other by means of the second fluid duct.

10. Radiation collector according to claim 6 or 7, wherein the frame consists essentially of concrete, and prefabricated concrete elements are preferably provided.

11. Radiation collector according to one of claims 3 to 10, wherein the second pressure chamber has a centrally placed core zone, and means are provided for operationally maintaining a pneumatic pressure in the core zone, which pressure is smaller than the pressure in the other regions of the second pressure chamber, in such a manner that during operation the concentrator concentrates the radiation in an improved manner due to the approximately parabolic, more pronounced curvature in the core zone and the less pronounced curvature in the other regions.

12. Radiation collector according to claim 11, wherein the means have a sealing arrangement which, between the side of the membrane of the concentrator which faces away from the radiation and the membrane, which is associated with that side, of the pressure cell, operationally separates the core zone from the other regions of the second pressure chamber, and wherein the means further have a fluid duct, through which fluid can flow out of the core zone in order to reduce the pneumatic pressure in the latter.

13. Radiation collector according to claim 12, wherein the core zone and the other regions of the second pressure chamber are connected to each other by means of at least one fluid duct, through which duct fluid can flow in both directions in order to maintain the setpoint pressure difference, wherein a fluid pump, which is preferably configured as a fan, is provided in the at least one fluid duct and can be operated in such a manner that the respective setpoint operating pressure prevails in the associated pressure chamber.

14. Solar collector according to claim 12, wherein the sealing arrangement has a sealing lip which interacts operationally with the membrane of the concentrator.

15. Solar collector according to claim 14, wherein during operation the sealing lip has a distance from the concentrator and/or a semi-permeable foam strip in such a manner that the quantity of fluid which flows out of the surrounding regions into the core zone is smaller than the quantity of fluid which can be conveyed by the fluid pump 84.

16. Solar collector according to claim 12, wherein the sealing arrangement is configured as a part of the support structure for the pressure cell and preferably consists of concrete.

17. Radiation collector according to one of the preceding claims, wherein the overpressure zone is divided into a plurality of segments (80, 81).

18. Radiation collector according to claim 17, wherein two adjacent segments bear against a fluid duct which is connected to the opening and are operationally connected to the said duct.

19. Radiation collector (1, 130) according to one of the preceding claims, wherein the concentrator (2, 132) consists of a membrane, consisting of PVC, PU and/or silicone-coated polyester fabric and/or a polyester foil preferably of Mylar, and/or fibreglass fabric, which is provided on one side with a coating which reflects radiation, wherein the reflective layer preferably consists of aluminium, which is particularly preferably vapour-deposited.

20. Radiation collector (1, 130) according to one of the preceding claims, wherein the pressure chamber wall (6, 133) consists at least partially of ethylene tetrafluoroethylene (ETFE) and is preferably reinforced with high-strength PET and/or with a steel or plastic web.

21. Radiation collector (1, 130) according to one of the preceding claims, wherein the collector has a rotationally symmetrical shape in the operating position and is preferably configured as a parabolic mirror or as a reflective spherical calotte.

22. Radiation collector (30) according to claim 21, wherein the pressure chamber wall (133) is drawn in towards the concentrator (32) at the site of the axis of symmetry in such a manner that the chamber has approximately the configuration of an annular chamber in the operating state.

23. Radiation collector (1, 30) according to claim 21, wherein the collector has the shape of a well or trough in the operating state.

24. Radiation collector (1, 30) according to claim 21, wherein the collector has the shape of a well with a parabolic cross section in the operating state.

25. Radiation collector (1, 30) according to one of the preceding claims, wherein the pressure chamber wall (10, 33, 59) is drawn in towards the concentrator (2, 32) along one or a plurality of surface lines of the latter in such a manner that the chamber has two or a plurality of segments which run in parallel with respect to each other.

26. Radiation collector (1, 30) according to one of the preceding claims, wherein a peripheral support ring (134) is provided, which mechanically stabilizes the pressure cell and which is preferably connected in one piece to the pressure cell.

27. Radiation collector (1, 30) according to claim 26, wherein the support ring (134) is configured as an inflatable structure.