Absorber pipe for solar heating applications

• US 7,013,887 B2
• Filed: 07/08/2003
• Issued: 03/21/2006
• Est. Priority Date: 07/08/2002
• Status: Expired due to Term

• Current Assignee: Schott Solar CSP GmbH (Carl-Zeiss-Stiftung)
• Original Assignee: Schott AG (Carl-Zeiss-Stiftung)
• Inventors: Kuckelkorn, Thomas, Benz, Nikolaus, Doenitz, Fritz-Dieter
• Primary Examiner(s): Price, Carl D.
• Application Number:
  US10/615,146
• Publication Number:
  US 20040050381A1
• Time in Patent Office: 987 Days
• Field of Search: 126/625, 126/653, 126/654, 126/655, 126/656, 126/657, 126/704, 126/705, 126/708, 126/712, 126/714, 126/652, 285/187, 285/300, 285/301, 285/145.5
• US Class Current: 126/652
• CPC Class Codes: F24S 10/45 the enclosure being cylindrical
• 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 2025/6013 Joining glass with non-glass elements
• CPC Class Codes: F24S 40/80 Accommodating differential expansion of solar collector elements
• CPC Class Codes: Y02E 10/40 Solar thermal energy, e.g. solar towers
• CPC Class Codes: Y02E 10/44 Heat exchange systems

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.

Claims

1. An absorber pipe, especially for a parabolic collector in a solar heat collecting apparatus, said absorber pipe comprising

a central metal pipe (3);

a glass sleeve tube (2) surrounding said central metal pipe (3) so that an annular space (4) is formed between the central metal pipe and the glass sleeve tube (2);

a glass-metal transitional element (5) on a free end of the glass sleeve tube; and

an expansion compensating device (10) connecting the central metal pipe and the glass-metal transitional element (5) with each other so as to be slidable relative to each other in a longitudinal direction and to guarantee a vacuum-tight seal between the free end of the glass sleeve tube and the central metal pipe;

wherein said expansion compensating device (10) comprises a folding bellows (11) and a connecting element (15, 15′

, 15″

), said folding bellows (11) is arranged between the glass-metal transitional element (5) and the central metal pipe (3), said folding bellows (11) extends into said annular space (4), said folding bellows (11) has an outer end (13) and an inner end (12), said inner end (12) is arranged within the annular space (4), said outer end (13) is arranged outside of the annular space, and said inner end (12) of said folding bellows (11) is connected to one end of said connecting element (15, 15′

, 15″

);

wherein another end of said connecting element (15, 15′

, 15″

) opposite to the one end connected to the folding bellows (11) is either connected to the central metal pipe (3) or to the glass-metal transitional element (5); and

wherein said folding bellows (11) and said connecting element (15, 15′

, 15″

) extend sufficiently into the annular space (4) and between the grass sleeve tube (2) and the central metal pipe (3), so that said glass-metal transitional element (5) is protected from radiation which would otherwise reach the glass-metal transitional element (5) after entering the glass sleeve tube (2);

wherein said glass-metal transitional element comprises a metal section glass-sealed directly within said free end of the glass sleeve tube.

2. The absorber pipe as defined in claim 1, wherein the outer end (13) of the folding bellows (11) is connected with the glass sleeve tube (2) by the glass-metal transitional element (5).

3. The absorber pipe as defined in claim 2, wherein the connecting element (15, 15″

) extends from said inner end (12) of the folding bellows (11) through a first circular space (8) formed between the folding bellows (11) and the central metal pipe (3).

4. The absorber pipe as defined in claim 3, wherein the connecting element (15, 15″

) has a circular disk (16) attached to the folding bellows (11) and said circular disk (16) goes over into a conical or cylindrical pipe-shaped section (17, 18′

) extending Through the first circular space (5).

5. The absorber pipe as defined in claim 3, wherein the connecting element (15, 15″

) is provided at least partially with a mirror surface on a side facing said central metal pipe (3).

6. The absorber pipe as defined in claim 1, wherein the inner end (12) of the folding bellows (11) is connected with the glass sleeve tube (2) by the connecting element (15′

) and by the glass-metal transitional element (5).

7. The absorber pipe as defined in claim 6, wherein the connecting element (15′

) extends from said inner end of the folding bellows (11) Through a second circular space (9) formed between the folding bellows (11) and the sleeve babe (2).

8. The absorber pipe as defined in claim 7, wherein said connecting element (15′

) comprises a circular disk (16) attached to said folding bellows (11) and said circular disk (18) goes over into a pipe-shaped cylindrical section (18) extending through said second circular space (9).

9. The absorber pipe as defined in claim 6, wherein said glass-metal transitional element (5) is attached to an outer collar (19) formed on said connecting element (15′

).

10. The absorber pipe as defined in claim 6, wherein the connecting element (15′

) is provided at least partially with a mirror surface on a side facing said central metal pipe (3).

11. The absorber pipe as defined in claim 1, further comprising another glass-metal transitional element (5) arranged on another end of the glass sleeve tube (2) opposite from the free end of the glass sleeve tube (2) and another expansion compensating device (10) connecting the central metal pipe and said another glass-metal transitional element (5) with each other, so as to be slidable relative to each other in a longitudinal direction and to guarantee a vacuum-tight seal between said another end of the glass sleeve tube and the central metal pipe.

12. The absorber pipe as defined in claim 1, wherein said annular space (4) is evacuated.

13. The absorber pipe as defined in claim 1, wherein said annular space (4) is filled with a noble gas.

14. A parabolic collector for a solar heat collecting apparatus, said parabolic collector comprising a longitudinally extending linear parabolic reflector (PR) having a focal line (FL) and at least one absorber pipe (1) arranged along said focal line;

wherein said at least one absorber pipe (1) comprises a central metal pipe (3), a glass sleeve tube (2) surrounding said central metal pipe (3) so that an annular space (4) is formed between the central metal pipe and the glass sleeve tube (2), a glass-metal transitional element (5) on a free end of the glass sleeve tube and an expansion compensating device (10) connecting the central metal pipe and the glass-metal transitional element (5) with each other so as to be slidable relative to each other in a longitudinal direction and to guarantee a vacuum-tight seal between the free end of the glass sleeve tube and the central metal pipe;

wherein said expansion compensating device (10) comprises a folding bellows (11) and a connecting element (15, 15′

, 15″

), said folding bellows (11) is arranged between the glass-metal transitional element (5) and the central metal pipe (3), said folding bellows (11) extends into said annular space (4), said folding bellows (11) has an outer end (13) and an inner end (12), said inner end (12) is arranged within the annular space (4), said outer end (13) is arranged outside of the annular space, and said inner end (12) of said folding bellows (11) is connected to one end of said connecting element (15, 15′

, 15″

);

wherein another end of said connecting element (15, 15′

, 15″

) opposite to the one end connected to the folding bellows (11) is either connected to the central metal pipe (3) or to the glass-metal transitional element (5); and

wherein said folding bellows (11) and said connecting element (15, 15′

, 15″

) extend sufficiently into the annular space (4) and between the glass sleeve tube (2) and the central metal pipe (3), so that Said glass-metal transitional element (5) is protected from radiation which would otherwise reach the glass-metal transitional element (5) after entering the glass sleeve tube (2);

wherein said glass-metal transitional element comprises a metal section glass-sealed directly within said free end of the glass sleeve tube.

15. The parabolic collector as defined in claim 14, wherein the outer end (13) of the folding bellows (11) is connected with the glass sleeve tube (2) by the glass-metal transitional element (5).

16. The parabolic collector as defined in claim 15, wherein the connecting element (15, 15″

) extends from said inner end (12) of the folding bellows (11) through a first circular space (8) formed between the folding bellows (11) and the central metal pipe (3).

17. The parabolic collector as defined in claim 16, wherein the connecting element (15, 15″

) has a circular disk (16) attached to the folding bellows (11) and said circular disk (16) goes over into a conical or cylindrical pipe-shaped section (17, 18′

) extending through the first circular space (5).

18. The parabolic collector as defined in claim 16, wherein the connecting element (15, 15″

) is provided at least partially with a mirror surface on a side facing said central metal pipe (3).

19. The parabolic collector as defined in claim 14, wherein the inner end (12) of the folding bellows (11) is connected with the glass sleeve tube (2) by the connecting element (15′

) and the glass-metal transitional element (5).

20. The parabolic collector as defined in claim 19, wherein the connecting element (15′

) extends from said inner end of the folding bellows (11) through a second circular space (9) formed between the folding bellows (11) and the sleeve tube (2).

21. The parabolic collector as defined in claim 20, wherein said connecting element (15′

) has a circular disk (16) attached to said folding bellows (11) and said circular disk (16) goes over into a pipe-shaped cylindrical section (18) extending through said second circular space (9).

22. The parabolic collector as defined in claim 19, wherein said glass-metal transitional element (5) is attached to an outer collar (19) formed on said connecting element (15′

).

23. The parabolic collector as defined in claim 19, wherein the connecting element (15′

) is provided at least partially with a mirror surface on a side facing said central metal pipe (3).

24. The parabolic collector as defined in claim 14, wherein the at least one absorber tube includes another glass-metal transitional element (5) arranged on another end of the glass sleeve tube (2) opposite from the free end of the glass sleeve tube (2) and another expansion compensating device (10) connecting the central metal pipe and said another glass-metal transitional element (5) with each other, so as to be slidable relative to each other in a longitudinal direction and to guarantee a vacuum-tight seal between said another end of the glass sleeve tube and the central metal pipe.

25. The absorber pipe as defined in claim 14, wherein said annular space (4) is evacuated.

26. The absorber pipe as defined in claim 14, wherein said annular space (4) is filled with a noble gas.

27. An absorber pipe, especially for a parabolic collector in a solar heat collecting apparatus, said absorber pipe comprising

a central metal pipe (3);

a glass sleeve tube (2) surrounding said central metal pipe (3) so that an annular space (4) is formed between the central metal pipe and the glass sleeve tube (2);

a glass-metal transitional element (5) on a free end of the glass sleeve tube; and

an expansion compensating device (10) connecting the central metal pipe and the glass-metal transitional element (5) with each other so as to be slidable relative to each other in a longitudinal direction and to guarantee a vacuum-tight seal between the free end of the glass sleeve tube and the central metal pipe;

wherein said expansion compensating device (10) comprises a folding bellows (11) and a connecting element (15, 15′

, 15″

), said folding bellows (11) is arranged between the glass-metal transitional element (5) and the central metal pipe (3), said folding bellows (11) extends in the longitudinal direction into said annular space (4), said folding bellows (11) has an outer end (13) and an inner end (12), said inner end (12) is arranged within the annular space (4), said outer end (13 arranged outside of the annular space, and said inner end (12) of said folding bellows (11) is connected to one end of said connecting element (15, 15′

, 15″

);

wherein another end of said connecting element (15, 15′

, 15″

) opposite to the one end connected to the folding bellows (11) is either connected to the central metal pipe (3) or to the glass-metal transitional element (5);

wherein said connecting element (15, 15′

, 15″

) elmer extends in the longitudinal direction between the bellows (11) and the central metal pipe (3) or between the bellows (11) and the glass sleeve tube (2); and

wherein said folding bellows (11) and said connecting element (15, 15′

, 15″

) extend sufficiently into the annular space (4) and between the glass sleeve tube (2) and the central metal pipe (3), so that said glass-metal transitional element (5) is protected from radiation which would otherwise reach the glass-metal transitional element (5) after entering the glass sleeve tube (2);

wherein said glass-metal transitional element comprises a metal section glass-sealed directly within said free end of the glass sleeve tube.