APPARATUS FOR PIVOTING SOLAR TROUGHS ON A CENTRAL AXIS
Solar trough apparatuses are disclosed, where a heat transfer fluid conduit remains fixed in a focal of a solar trough as the solar trough tracks the sun. The support structures can be ring or arcuate structures, where rotation is about their central axis and the trough is support in them so that the focal zone is coincident with the axis of rotation and the conduit is situated in the focal zone eliminating the need for articulated or flexible conduit.
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1. Field of the Invention
Embodiments of the present invention relate to solar trough apparatuses, where a heat transfer fluid conduit remains fixed in a focal point of the solar trough as the solar trough tracks the sun.
More particularly, embodiments of the present invention relate to solar trough apparatuses, where a heat transfer fluid conduit remains fixed in a focal point, line or zone of the solar trough as the solar trough tracks the sun. The solar troughs of this invention generally include a plurality of trough sections. The system also includes a support structure, which supports the trough and conduit and rotates the trough while maintaining the conduit centered in the focal point, line or zone of the solar trough eliminating the need for articulated heat transfer fluid conduits. The support structure can include a separate trough support structure and a separate conduit support structure or the support structure can support both the trough and the conduit.
2. Description of the Related Art
Solar thermal troughs are one of three common applications for solar-thermal energy. They are mechanically simpler and less costly than solar heliostat towers and are capable of attaining higher temperatures than Fresnal mirror arrays. Solar troughs operate by reflecting sunlight from a parabolic mirror and concentrating it onto a pipe carrying a heat transfer fluid (HTF.) Once heated, the HTF is sent into a power system to transfer its heat to a working fluid which then produces power in the power system.
However, solar troughs have a significant limitation. Because the pipes carrying the HTF are mounted above the parabolic mirrors and the parabolic mirrors must pivot to track the sun, the pipes carrying HTF must be articulated. The points of articulation are mechanically complex, require maintenance and limit the pressure at which HTF can be sent through the pipes. This limited pressure in turn limits the possible performance of the power system that generates electricity from the solar-trough heated HTF.
Thus, there is a need in the art for improved solar troughs for use in solar trough type power generation systems that eliminate the need for articulated heat transfer fluid conduits so that the solar troughs can track the sun as the rotation assembly rotates the troughs.
SUMMARY OF THE INVENTIONEmbodiments of the present invention provide solar collector systems including a solar trough subsystem including a plurality of solar trough sections. Each section includes one parabolic solar collector or a plurality of parabolic solar collectors. The troughs are supported by a support subsystem, where a center of rotation of the support subsystem is coincident with a focal point, line or zone of the trough subsystem and where the support subsystem rotates the trough to track the sun maximizing solar collection, while maximizing heat transfer fluid heating passing through the conduit stationary and coincident with the focal zone. The systems also include a heat transfer fluid conduit subsystem that extends a length of the trough subsystem coincident with the focal zone. The support structure subsystem can include a separate trough support structure and a separate conduit support structure or a single support structure that supports both the trough subsystem and the conduit subsystem. In certain embodiments, the trough support structures comprises ring support structures, where the trough support structures support each trough section and a separate conduit support structure situated between ring support structures of adjacent trough sections. In other embodiments, the support structures comprises arcuate support structures supporting each trough section and a separate conduit support structure situated between arcuate structures of adjacent trough sections. In the other embodiments, the support structure comprises ring support structures, where each ring support structures supports two adjacent trough sections, while simultaneously supporting the conduit. In other embodiments, the support structure comprises arcuate support structures, where each arcuate support structure supports two adjacent trough sections, while simultaneously supporting the conduit. The rotation of the trough by the support structure permits the trough to track the sun maximizing solar collection, while maintaining the focal zone focused on the conduit without having motion of the conduit because the conduit is situated coincident with the focal zone of the trough.
Embodiments of this invention provide methods for operating solar collector systems including providing a solar trough subsystem, a heat transfer fluid conduit subsystem, a support subsystem, and a heat conversion subsystem, where a center of rotation of the support subsystem is coincident with the focal zone of the trough. The support subsystem rotates the trough to track the sun maximizing solar collection efficiency, while maintaining a focal zone of the trough stationary and where a conduit of the conduit subsystem is situated in the focal zone to maximize heating without the need for articulated conduit segments. The methods include focusing solar radiation on the heat transfer fluid conduit coincident with a focal zone of the solar trough. The methods also include pumping a cold heat transfer fluid through the conduit at a pressure and a flow rate to maximize heating of the heat transfer fluid to form a hot heat transfer fluid. The methods include rotating the trough, while pumping, to track the sun, while maintaining the focal line or zone substantially stationary maximizing solar collection and simultaneously maximizing heat transfer fluid heating. The methods also include transferring a portion of the heat in the hot heat transfer fluid to a working fluid of a heat conversion subsystem to form a cold heat transfer fluid. The methods also include converting a portion of the heat in the working fluid into a useable for of energy in the heat conversion subsystem.
Embodiments of this invention provide solar trough system including a solar trough collector subsystem, a heat transfer conduit subsystem, and a support subsystem, where a center of rotation of the support subsystem is coincident with a focal zone of the trough and where the conduit is situated in the focal zone to maximize heating without articulated conduit segments. The methods include focusing solar radiation on the heat transfer fluid conduit coincident with a focal zone of a solar trough. The methods also include pumping a cold heat transfer fluid through the conduit at a pressure and a flow rate to maximize heating of the heat transfer fluid to form a hot heat transfer fluid. The methods include rotating, while pumping, the trough to track the sun, while maintaining the focal line or zone substantially stationary to track the sun maximizing solar collection and simultaneously maximizing heat transfer fluid heating.
The invention can be better understood with reference to the following detailed description together with the appended illustrative drawings in which like elements are numbered the same:
The inventor has found that solar trough systems can be constructed with non-articulated pipes or conduits. Solar trough systems including non-articulated heat transfer fluid (HTF) pipes or conduits can be pressurized to any pressure that does not exceed a rupture pressure of the pipe, while articulated pipe or conduits assemblies have a more limited operating pressure. The inventor has also found that without articulation, there are no conduit bearings or joints to maintain or risk failure, and the costs of articulating the HTF pipes and maintaining the articulated pipes are not incurred.
The invention operates by making an axis of rotation of a solar trough the same as a focal zone of the trough so that an axis of a HTF pipe can be made coincident with the focal zone of the trough. As the trough rotates to track the sun, its focal zone maintains fixed or substantially fixed as does the pipe or conduit, which remains stationary or substantially stationary within the focal zone of the trough. Because the focal zone is coincident with the axis of rotation of the trough, the heat transfer fluid conduit remains fixed or stationary.
In a conventional solar trough apparatus, an axis of rotation of the trough is set at a bottom of a parabolic mirror or trough. A motor mounted on elevated pedestals or struts holds up the trough and rotates it to track the sun. The HTF pipe is held in a focal point of the trough by further struts. At the edges of the trough, the HTF pipe is attached to articulated or flexible pipe sections so the pipe moves as the trough rotates to maintain the pipe in the focal zone of the trough.
In embodiments of this invention, the solar trough system comprising a solar trough including a plurality of trough sections. The system also includes a heat transfer conduit subsystem and a support subsystem. The support subsystem supports and rotates the trough so that the trough tracks the sun, while maintaining a trough focal zone fixed or substantially fixed, i.e., the axis of rotation of the trough is coincident with its focal zone or line. The support subsystem also supports the conduit, where the conduit is situated coincident with the focal zone of the trough. In certain embodiments, the support subsystem comprises ring support structures. In certain embodiments, each section includes two ring support structures per trough section, one positioned at each end of the trough sections. In other embodiments, adjacent sections share a single ring support structure so that there are N+1 ring support structures instead of 2N ring support structures. The ring support structures include a means for rotating the ring support structures. There are a variety of ring support structures that can be used to support and rotate the rings, where the center of rotation is coincident with the focal zone of the trough. The HTF conduit extends the length of the trough and is situated or supported coincident with the axis of rotation of the rings. The conduit support structures can be separate from the ring support structures or the conduit can be supported by the ring support structure. In certain cases, the solar trough and support rings do not actually touch the HTF conduit, which is supported by its own struts. In all cases, the HTF pipe, therefore, does not move, and requires no articulation because the center of rotation of the trough is coincident with the focal zone of the trough.
Embodiments of the solar trough systems and apparatuses include two rings, mounted perpendicularly on either end of a parabolic solar trough assembly and a heat transfer fluid pipe or conduit, where the pipe extends between the rings and is positioned so that the pipe passes through a center of each ring so that the pipe is substantially coincident with a focal axis or zone of the parabolic solar trough assembly. The parabolic trough and its underlying support structure is then affixed to the rings by means of several struts supporting the trough from beneath and connecting it to the inside of the ring. The diameter of the rings is such that, with the focal point of the trough as the center of the ring, the trough touches the ring at the trough's widest point.
Suitable heat transfer fluids for use in this invention include, without limitation, meltable salts, synthetic heat transfer fluids such as THERMINOL® (a registered trademark of Solutia Inc. Corporation) and DOWTHERM® (a registered trademark of Dow Chemicals Corporation), natural heat transfer fluids, other fluids capable of acting as a heat transfer fluid, and mixtures or combinations thereof.
Suitable working fluids for use in this invention include, without limitation, a multi-component working fluid including at least one lower boiling component and at least one higher boiling component. In certain embodiments, the working fluids include an ammonia-water mixture, a mixture of two or more hydrocarbons, a mixture of two or more freon, a mixture of hydrocarbons and freon, or the like. In general, the fluid can comprise mixtures of any number of compounds with favorable thermodynamic characteristics and solubility. In certain embodiments, the fluid comprises a mixture of water and ammonia.
DETAILED DESCRIPTION OF THE DRAWINGSTwo Ring Supports Per Trough Section with Conduit Supports
Referring now to
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Two Ring Supports Per Trough Section without Conduit Supports
Referring now to
Referring now to
An advantage of this variant is that the drive motors, whether driving one of the supporting wheels or a dedicated drive wheel, are mounted at ground level, making access and maintenance simpler than in the prior art, where the drive motors to rotate the solar trough are mounted at the top of the support struts which hold up the solar trough. A further advantage is that a single powerful drive motor could be installed (with a chain transmission, for instance) to turn all the drive wheels of an entire row of solar troughs, replacing one or more separate small motors for each trough, as is the case in the prior art.
Rings Share Ring SupportsReferring now to
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In the second variant, each ring has supporting struts that attach the ring to a centered hollow pipe (which is of greater diameter than the HTF pipe.) For each ring, the hollow pipe projects out away from the trough, along the axis of rotation. Each ring is then supported by a large strut which is topped with a short section of pipe which is just large enough to hold the outer diameter of the hollow pipe attached to the ring. In this way, these large struts, which are set to either side of the ring-and-trough apparatus, support the ring-and-trough apparatus, holding it clear of the ground and allowing it to rotate about the axis of the HTF pipe. It should be noted that the HTF pipe itself passes through the pipe sections at the center of the rings and does not touch them.
In the second variant, a drive motor is placed on the struts holding up the entire rings-and-trough apparatus and rotates the apparatus about the axis of the HTF pipe to track the sun. It is possible to use a single drive motor per strut or one per apparatus, with the motor-less strut made so as to allow for free and smooth rotation of the apparatus (for instance, by means of ball bearings.)
Arcuate Support StructuresReferring now to
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An advantage of this variant is that the drive motors, whether driving one of the supporting wheels or a dedicated drive wheel, are mounted at ground level, making access and maintenance simpler than in the prior art, where the drive motors to rotate the solar trough are mounted at the top of the support struts which hold up the solar trough. A further advantage is that a single powerful drive motor could be installed (with a chain transmission, for instance) to turn all the drive wheels of an entire row of solar troughs, replacing one or more separate small motors for each trough, as is the case in the prior art.
Note that one experienced in the art can engineer other alternate variants and mechanisms to support the solar-trough and allow it to pivot with the HTF pipe as its axis of rotation.
Note also than a third conceptual variant is possible, where instead of ensuring that there is no contact between the HTF pipe and the solar-trough apparatus, instead the solar-trough apparatus is suspended from the HTF pipe in such a way as to allow the solar-trough apparatus to rotate about the axis of the solar trough pipe. In this variant, motors would be mounted around the HTF pipe, allowing the solar-trough apparatus to rotate about the pipe, which would be fixed and immobile. In this variant, the HTF pipe would have to be made far stronger (and likely more costly) than in the other variants described above, since it would have to constantly carry the weight of the solar-trough apparatus, as well as the motors required to rotate the solar-trough apparatus. However, this is, none the less, a possible way of having the solar trough apparatus rotate with about the axis of the HTF pipe.
There are several advantages offered by the proposed invention.
Firstly, because (in the first and second variants described) the HFT pipe is not in contact with the trough apparatus and does not move, it can be built (in all variants) with no articulation, reducing installation and maintenance costs and more crucially, allowing for much higher pressurization of the HTF in the pipe, in turn allowing for better performance of the power system.
Secondly, (in the first variant described) it is possible to reduce the number of drive motors and to place these motors at ground level, making maintenance easier and less expensive.
Thirdly, the entire trough can be mounted lower to the ground, reducing construction costs and easing both maintenance and the cleaning of the mirror surface of the trough.
Fourth, (in the first and second variants described) because the HTF pipe is not attached to the trough, cleaning the mirror surface of the is made much easier; there are no struts projecting from the surface of the trough.
Lastly, the lack of struts projecting from the surface of the trough means that the trough can be a single continuous mirror, improving its overall ability to focus sunlight onto the HTF pipe. The total area of shadow cast by the ring structures holding the trough in the proposed invention can be made smaller than the shadows cast by the struts projecting from the trough used to hold the HTF pipe in the prior art.
In summary, the present invention should reduce the cost of installation of solar troughs (with their associated HTF pipes,) reduce the costs of maintenance and cleaning of solar troughs and by allowing higher pressure in the HTF pipes, increase the performance and thus the power generation of a given surface area of solar troughs.
Alternate Drive AssembliesReferring now to
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Referring now to
It should be recognized that although several different drive units and mechanisms have been shown, that any drive system capable of rotating the ring or arcuate structures will do as well including, without limitation, belt drives, direct drives, fluid drives, or the like. Additionally, the drives can utilize electric motors or internal combustion engines.
All references cited herein are incorporated by reference. Although the invention has been disclosed with reference to its preferred embodiments, from reading this description those of skill in the art may appreciate changes and modification that may be made which do not depart from the scope and spirit of the invention as described above and claimed hereafter.
Claims
1. A solar collector system comprising:
- a solar trough subsystem including: a plurality of solar trough sections, where each section includes one parabolic solar collector or a plurality of parabolic solar collectors having a focal zone,
- a heat transfer fluid conduit subsystem including a conduit extending a length of the trough subsystem coincident with the focal zone,
- a support subsystem for supporting the trough subsystem, where a center of rotation of the support subsystem is coincident with a focal point, line or zone of the trough subsystem and where the support subsystem rotates the trough to track the sun maximizing solar collection, while maintaining the focal zone fixed and focused on the conduit thereby maximizing solar heating of a heat transfer fluid flowing through the conduit stationary and coincident with the focal zone.
2. The system of claim 1, wherein the support structure subsystem includes a separate trough support structure and a separate conduit support structure.
3. The system of claim 2, wherein the trough support structure comprises ring support structures, where the trough support structures support each trough section and a separate conduit support structure situated between ring support structures of adjacent trough sections.
4. The system of claim 2, wherein the trough support structures comprises arcuate support structures supporting each trough section and a separate conduit support structure situated between arcuate structures of adjacent trough sections.
5. The system of claim 2, wherein the trough support structures comprises ring support structures, where each ring support structures supports two adjacent trough sections, while simultaneously supporting the conduit.
6. The system of claim 2, wherein the trough support structures comprises arcuate support structures, where each arcuate support structure supports two adjacent trough sections, while simultaneously supporting the conduit.
7. The system of claim 1, wherein the support structure subsystem includes a single support structure that supports both the trough subsystem and the conduit subsystem.
8. The system of claim 7, wherein the trough support structures comprises ring support structures, where each ring support structures supports two adjacent trough sections, while simultaneously supporting the conduit.
9. The system of claim 2, wherein the trough support structures comprises arcuate support structures, where each arcuate support structure supports two adjacent trough sections, while simultaneously supporting the conduit.
10. A method for operating solar collector systems comprising:
- providing a solar trough subsystem, a heat transfer fluid conduit subsystem having a conduit extending a length of the solar trough subsystem, a support subsystem, and a heat conversion subsystem, where a center of rotation of the support subsystem is coincident with the focal zone of the trough subsystem and where the conduit is coincident with the focal zone of the trough subsystem;
- focusing solar radiation on the conduit; and
- pumping cold heat transfer fluid through the conduit at a pressure and a flow rate to maximize heating of the heat transfer fluid to form a hot heat transfer fluid, while rotating the trough subsystem using the support subsystem to track the sun maximizing solar collection efficiency and to maintain a focal zone of the trough subsystem stationary and where a conduit is situated in the focal zone to maximize heating without the need for articulated conduit segments.
11. The method of claim 10, further comprising:
- transferring a portion of the heat in the hot heat transfer fluid to a working fluid of a heat conversion subsystem to form a cold heat transfer fluid.
12. The method of claim 10,
- converting a portion of the heat in the working fluid into a useable for of energy in the heat conversion subsystem.
13. The method of claim 10, further comprising:
- transferring a portion of the heat in the hot heat transfer fluid to a working fluid of a heat conversion subsystem to form a cold heat transfer fluid, and
- converting a portion of the heat in the working fluid into a useable for of energy in the heat conversion subsystem.
13. The method of claim 10, wherein the support structure subsystem includes a separate trough support structure and a separate conduit support structure.
14. The method of claim 13, wherein the trough support structure comprises ring support structures, where the trough support structures support each trough section and a separate conduit support structure situated between ring support structures of adjacent trough sections.
15. The method of claim 13, wherein the trough support structures comprises arcuate support structures supporting each trough section and a separate conduit support structure situated between arcuate structures of adjacent trough sections.
16. The method of claim 13, wherein the trough support structures comprises ring support structures, where each ring support structures supports two adjacent trough sections, while simultaneously supporting the conduit.
17. The method of claim 13, wherein the trough support structures comprises arcuate support structures, where each arcuate support structure supports two adjacent trough sections, while simultaneously supporting the conduit.
18. The method of claim 10, wherein the support structure subsystem includes a single support structure that supports both the trough subsystem and the conduit subsystem.
19. The method of claim 18, wherein the trough support structures comprises ring support structures, where each ring support structures supports two adjacent trough sections, while simultaneously supporting the conduit.
20. The method of claim 18, wherein the trough support structures comprises arcuate support structures, where each arcuate support structure supports two adjacent trough sections, while simultaneously supporting the conduit.
21. A solar trough system comprising:
- a solar trough collector subsystem,
- a heat transfer conduit subsystem, and
- a support subsystem,
- where a center of rotation of the support subsystem is coincident with a focal zone of the trough subsystem and where the conduit is situated in the focal zone to maximize heating without articulated conduit segments.
Type: Application
Filed: Feb 3, 2010
Publication Date: Aug 4, 2011
Applicant: KALEX, LLC (Belmont, CA)
Inventor: Mark Kalina (Belmont, CA)
Application Number: 12/699,871
International Classification: F24J 2/38 (20060101); F24J 2/12 (20060101); F24J 2/24 (20060101); F24J 2/00 (20060101);