TROUGH COLLECTOR FOR A SOLAR POWER PLANT

• US 20110114083A1
• Filed: 03/29/2009
• Published: 05/19/2011
• Est. Priority Date: 03/28/2008
• Status: Abandoned Application

• Current Assignee: Airlight Energy IP SA
• Original Assignee: Airlight Energy IP SA
• Inventors: Pedretti, Andrea
• Application Number:
  US12/934,832
• Publication Number:
  US 20110114083A1
• Time in Patent Office: Days
• US Class Current: 126/657
• CPC Class Codes: F24S 2023/88 Multi reflective traps
• CPC Class Codes: F24S 2070/62 Heat traps
• CPC Class Codes: F24S 23/745 flexible
• CPC Class Codes: F24S 23/79 with spaced and opposed interacting reflective surfaces
• CPC Class Codes: Y02E 10/40 Solar thermal energy, e.g. solar towers
• CPC Class Codes: Y10T 29/49355 Solar energy device making

Abstract

A trough collector (1) for solar power plants comprises a pressure cell (25) containing an absorber pipe (42) for a heat-carrying fluid and also a secondary concentrator which is likewise arranged in the pressure cell (25). The pressure cell (25) thus can be reduced in height, which eliminates the need for reinforcements in the form of a framework structure for the pressure cell (25), which are otherwise required.

Claims

1. A trough collector for a solar power plant comprising:

a concentrator arranged in a pressure cell such that it can be loaded with pressure and constructed as a flexible membrane;

wherein the concentrator concentrates solar radiation incident into the pressure cell under operating pressure towards a focal line region running outside of the pressure cell, and with an absorber element for absorption of a concentrated solar radiation;

wherein the absorber element is arranged in the pressure cell; and

wherein further within the pressure cell a secondary concentrator is provided which lies in a path of a concentrating radiation and is constructed in such a manner that the concentrated radiation is further concentrated toward a secondary focal line region or a secondary focal line at a location of the absorber element.

2. The trough collector as claimed in claim 1, wherein:

the pressure cell at least partially formed from a flexible membrane has a transparent region for solar radiation to be reflected;

the concentrator comprises;

a side which faces the transparent region and reflects the solar radiation; and

a side which faces away from the radiation;

wherein the concentrator subdivides the pressure cell into a first pressure chamber and a second pressure chamber; and

wherein means constructed as fans are provided to operationally generate and maintain pressure at a predefined level in the first and second pressure chambers if a volume of one or both pressure chambers is changed in operation by means of external influences.

3. The trough collector as claimed in claim 1, wherein a 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.

4. The trough collector as claimed in claim 1, wherein:

the secondary concentrator is arranged opposite the concentrator in a vicinity of a membrane with a region which is transparent for solar radiation; and

wherein the absorber element runs between the concentrator and the secondary concentrator.

5. The trough collector as claimed in claim 1, wherein:

the absorber element comprises a jacket for reducing heat emission to the outside;

wherein the absorber element further comprises a thermal opening running longitudinally in the jacket;

wherein the thermal opening allows passage of solar radiation further concentrated by the secondary concentrator through the jacket into an interior of the absorber element; and

wherein the absorber element is further constructed in such a manner that a heat-transporting fluid can circulate between the jacket and the interior for transporting radiant heat incident through the thermal opening away.

6. The trough collector as claimed in claim 1, wherein the concentrator and the secondary concentrator are each divided into two longitudinally running mutually symmetrical regions.

7-9. -9. (canceled)

10. A method for producing a secondary concentrator for a solar collector, which comprises the following steps for defining a shape of a reflective surface of the secondary concentrator:

taking at least one cross-sectional plane of the secondary concentrator, wherein the following is carried out therein;

defining a unit vector s(φ

) of an incident solar ray;

defining the unit vector s′

(φ

) of the solar ray reflected on the concentrator;

taking the unit vector s″

(φ

) of the solar ray reflected on the secondary concentrator;

defining a number of points SM(φ

) on the secondary concentrator by means of a vector PM(φ

), wherein the vector PM(φ

) lies on the concentrator, and where SM(φ

)=PM(φ

)+k·

s′

(φ

);

defining a factor k in such a manner that s″

(φ

) goes through a predefined focal point or a focal line F of the arrangement consisting of the concentrator and the secondary concentrator;

defining a curve, and thus the sought shape of the reflective surface which goes through the obtained number of points SM(φ

); and

transferring the curve obtained using the above steps onto the secondary concentrator to form its reflective surface.

11. The method as claimed in claim 10, wherein the factor k is defined by an equalization of scalar products

s′

·

t(φ

)=s″

·

t(φ

)

wherein t(φ

) is a tangent which is placed on the secondary concentrator at the point SM(φ

).

12. The method as claimed in claim 11, wherein the equation

s′

·

t(φ

)=s″

·

t(φ

)

is resolved according to dk/dφ

, wherein the values of k are defined numerically from a resulting elliptical integral.

13. The method as claimed in claim 10, wherein the incident solar rays are assumed to be parallel for simplification.

14. The method as claimed in claim 10, wherein the concentrator is assumed to have an arcuate cross section.

15. The method as claimed in claim 10, wherein an origin of the co-ordinate system is assumed to lie in a center point of curvature of the concentrator.

16. The method as claimed in claim 10, wherein the curve is defined by means of the method of least squares by means of the points SM(φ

) obtained.

17. The method as claimed in claim 10, wherein the curve is transferred to a foam block and the produced curved surface is covered with a reflective foil.

18. (canceled)

19. A trough collector for a solar power plant comprising the following steps for defining a shape of a reflective surface of a secondary concentrator:

taking at least one cross-sectional plane of the secondary concentrator, wherein the following is carried out therein;

defining a unit vector s(φ

) of an incident solar ray;

defining the unit vector s′

(φ

) of the solar ray reflected on the concentrator;

taking the unit vector s″

(φ

) of the solar ray reflected on the secondary concentrator;

defining a number of points SM(φ

) on the secondary concentrator by means of a vector PM(φ

), wherein the vector PM(φ

) lies on the concentrator, and where SM(φ

)=PM(φ

)+k·

s′

(φ

);

defining a factor k in such a manner that s″

(φ

) goes through a predefined focal point or a focal line F of the arrangement consisting of the concentrator and the secondary concentrator;

defining a curve, and thus the sought shape of the reflective surface which goes through the obtained number of points SM(φ

); and

transferring the curve obtained using the above steps onto the secondary concentrator to form its reflective surface.

20. (canceled)