Patent Application
20110088685
The present invention relates to the field of solar energy collector systems, and more particularly, to a solar dish collector system and related methods.
There are a variety of solar energy collector systems available for converting solar energy into other forms of energy that can be more readily used or stored. For example, concentrating collectors focus or concentrate the sun's radiation energy in a particular area.
One type of concentrating collector is the parabolic trough collector. A parabolic trough collector uses an elongated reflective trough having a parabolic cross-section to concentrate the sun's radiation along a focal line extending through the focal points of the parabolic elements of the trough. A conduit is positioned along the focal line and a heat transfer liquid is circulated through the conduit, where it will be heated by the sun's energy. Satisfactory flow rates at high temperatures can be obtained from these collectors.
With the assistance of a tracking system, parabolic trough collectors can become very efficient as they follow the movement of the sun. As solar energy collector systems incorporating parabolic type collectors are used to satisfy larger energy requirements, they become physically larger. As the parabolic trough solar collector panel increases in size, so does the cost and weight associated with holding and rotating the panel.
Another contributing factor towards cost is the conduit positioned along the focal line of the parabolic trough solar collector panel. The conduit typically includes a glass collector tube that is fragile, and has a high cost associated therewith. Even in view of the advances made in parabolic trough solar energy collectors, there is still a need for a low cost, lightweight and efficient solar energy collector system.
In view of the foregoing background, it is therefore an object of the present invention to provide a solar energy collector system that overcomes the shortfalls of a parabolic trough solar energy collector.
This and other objects, advantages and features in accordance with the present invention are provided by a solar dish collector system comprising a solar dish collector panel for reflecting sunlight, and a conduit adjacent the solar dish collector panel. The conduit may comprise a supply tube to provide fluid to be heated by the reflected sunlight, and a return tube to return the heated fluid.
A collector may enclose open ends of the supply and return tubes, and the collector may be positioned to receive the reflected sunlight from the solar dish collector panel. The fluid from the supply tube may at least partially fill the collector and is heated by the reflected sunlight while circulating therein. The heated fluid may be returned via the return tube.
The solar dish collector panel may be configured to reflect the sunlight to a focal point, and the collector may be positioned at the focal point. The conduit may extend below the solar dish collector panel, and the supply and return tubes of the conduit may extend upwards through the solar dish collector panel.
The solar dish collector panel may be coupled to the conduit. The solar dish collector system may further comprise at least one actuator coupled to the conduit for pivotally rotating the conduit so that the solar dish collector panel tracks position of the sun.
The conduit advantageously functions as a fluid transfer device, supports the solar dish collector panel, and can be rotated based on the position of the sun in order for the solar dish collector panel to receive the maximum sunlight. Since the collector receives the reflected sunlight to heat the fluid circulating therein, the conduit does not need to be a glass tube. A glass tube is costly and fragile. Instead, the conduit may be an insulated tube or pipe, for example.
The collector may be configured as a sphere that may comprise a clear material on sides thereof to receive the reflected sunlight, and an opaque coating on a top portion thereof to prevent the reflected sunlight from escaping. The open ends of the supply and return tubes may be spaced apart from one another within the collector, with the open end of the supply tube being positioned below the open end of the return tube. This allows the incoming fluid to circulate within the collector from the bottom and exit from the top.
The collector may comprise glass, for example. In this embodiment, the solar dish collector system may further comprise a protective top over the collector for protection thereof. In addition, the solar dish collector system may further comprise a photovoltaic cell within the collector for generating electricity.
To increase solar consumption within the collector, the solar dish collector system may further comprise an interior collector positioned within the collector for receiving the reflected sunlight, and for directly contacting the fluid. The interior collector may be opaque, for example. The outer surfaces of the interior collector may comprise at least one of dimpled and corrugated outer surfaces to provide an increased surface area for contacting the fluid circulating within the collector. Moreover, the interior collector may be hollow and include a plurality of openings therethrough to further increase the surface area for contacting the fluid circulating within the collector.
The solar dish collector panel may comprise a reflective surface comprising at least one of a reflective film and a reflective coating. The solar dish collector system may further comprise at least one tilting device coupled to the at least one actuator for adjusting a latitudinal angle of the at least one conduit with respect to ground.
Another aspect is directed to a method for collecting solar energy using a solar energy collector system as defined above. The method may comprise reflecting sunlight using a solar dish collector panel. A conduit may be positioned adjacent the solar dish collector panel that comprises a supply tube to provide fluid to be heated by the reflected sunlight, and a return tube to return the heated fluid. The method may further comprise enclosing open ends of the supply and return tubes using a collector positioned to receive the reflected sunlight from the solar dish collector panel. The fluid from the supply tube may at least partially fill the collector and be heated by the reflected sunlight while circulating therein. The heated fluid may then be returned via the return tube.
The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout, and prime notation is used to indicate similar elements in alternative embodiments.
Referring initially to
The solar dish collector panel 12 is coated with a reflective material for directing sunlight to a central point. In the illustrated solar dish collector system 10, sunlight is directed to a collector 18 that is positioned at the central point. Fluid from the conduit 16 passes through the collector 18 for heating. The illustrated collector 18 is a clear sphere coupled to the conduit 16. Although the collector 18 is illustrated as a sphere, other shapes may be used.
As illustrated in
While circulating within the collector 18, the fluid is heated by the sunlight reflected from the solar dish collector panel 12. To increase solar consumption within the collector 18, a dark colored interior collector 24 may be placed within the collector. The interior collector 24 is placed around the return tube 22, and is preferably black for insuring that the sunlight reflected from the solar dish collector panel 12 remains within the collector 18 for heating the fluid. In other embodiments, the interior collector 24 may be placed separate from the return tube 22.
Since sunlight enters from the sides of the collector 18, a top portion 26 of the collector may be black to prevent the entered sunlight from escaping. Consequently, the black top portion 26 reflects the sunlight. To keep the reflected sunlight within the collector, the sides of the collector 18 may be silver. Separately or in addition to the black and silver coatings, a one-way film may be applied to the collector 18. A function of the one-way film is to allow sunlight in but not let it escape. These features advantageously increase solar absorption by the collector 18.
Although the interior collector 24 is illustrated as a sphere, other shapes may be used. The interior collector 24 may be hollow and include a plurality of openings 28 therethrough. This provides a greater surface area in which the interior collector 24 can contact the fluid for heating thereof. In lieu of openings 28, the interior collector 24 may be dimpled or corrugated, for example.
The return tube 22 may also have a photovoltaic cell 29 associated therewith, as illustrated in
In one embodiment, the collector 18 is glass. As readily appreciated by those skilled in the art, other types of transparent materials may be used. When the collector 18 is glass or some other delicate material, a clear umbrella cap 31 comprising a non-delicate material may be placed on top of the collector 18 for protection from high winds and flying debris. In one embodiment, the cap 31 is directly attached to the top portion 26 of the collector 18. In other embodiments, the cap 31 may be attached to the solar dish collector panel 12 or to one or both of the supply and return tubes 20, 22.
The conduit 16 may be an insulated pipe or tube as readily appreciated by those skilled in the art. The pipe or tube may be cast iron or plastic, for example, although other types of material may be readily used. An advantage of the insulated pipe or tube is that it is less expensive and more durable as compared to a glass conduit normally associated with a parabolic type collector. In a parabolic type collector, the glass conduit runs along a focal line, which extends the length of the parabolic type collector. In contrast, the glass collector 18 is at a focal point of the solar dish collector system 10.
Since the base 14 of the solar dish collector system 10 is mounted to the conduit 16, rotation of the conduit causes the solar dish collector panel 12 to be rotated. In other words, the conduit 16 is the pivot point. The base 14 is mounted to the conduit 16 at connection points 40 and 42. The connection points 40 and 42 also include conduit supports 44 and 46 for elevating the conduit 16 above ground.
Still referring to
The solar dish system 10 is rotated to track position of the sun. One or more sensors 41 are used to determine position of the solar dish collector system 10 with respect to the sun. An output signal from each sensor 41 is applied to an actuator 30. Since the solar dish system 10 is mounted to the conduit 16, a chain or belt driven motor is not needed as with a parabolic type collector. This also advantageously reduces weight and cost.
The base 14 and solar dish collector panel 12 may be formed out of a molding material comprising a thermoplastic material or a thermosetting material, as readily appreciated by those skilled in the art. The molding material may be based on a polymer or elastomer. The polymers may also be fiber-reinforced. Other types of plastic composites may be used, as readily appreciated by those skilled in the art. In addition, the base 14 and solar dish collector panel 12 may be formed out of metal.
The solar dish collector panel 12 has a reflective surface for directing the sunlight toward the clear collector 16. A reflective film or coating is on the reflective surface. The coating may be a reflective paint, for example. The use of mirrors is avoided, which would significantly add to the weight and cost of the solar dish collector system 10.
The dimensions of a solar dish collector system 10 vary depending on the intended application. The selected dimensions typically allow for easy portability. For illustration purposes, the solar dish collector system 10 may be 8 feet wide by 8 feet deep by 4 feet tall, for example.
To allow the solar dish collector panel 12 to track the sun from horizon to horizon, the base 14 has a triangular shape, as illustrated in
A jackscrew or tilting device 51 may be carried by each conduit support 44 and 46 for adjusting the angle of the solar dish collector system 10 to compensate for the seasonal rotation of the sun. This rotation may be limited to within plus/minus 10 degrees, for example. A controller 35 is connected to the jackscrews or tilting devices 43 for control thereof so that each conduit support 44, 46 is incrementally adjusted to provide the desired rotation, as readily appreciated by those skilled in the art. One controller 35 may control the jackscrews or tilting devices 51 for a plurality of solar dish collector panels 12 making up the solar dish collector system 10. This advantageously maximizes collection of the solar energy from the sun by the solar dish collector system 10.
In another embodiment, the base 14′ of the solar dish collector system 10′ is rectangular shaped, as illustrated in
To achieve collection areas required for some applications, a plurality of solar dish collector system 10′ may be positioned side-by-side. As illustrated in
Another aspect is directed to a method for collecting solar energy using a solar energy collector system 10 as defined above. Referring now to the flowchart 100 illustrated in
The open ends of the supply and return tubes 20, 22 are enclosed at Block 108 using a collector 18 positioned to receive the reflected sunlight from the solar dish collector panel 12. The fluid from the supply tube 20 at least partially fills the collector 18 at Block 110, and is heated by the reflected sunlight while circulating therein. The heated fluid may then be returned via the return tube 22 at Block 112. The method ends at Block 114.
Many modifications and other embodiments of the invention will come to the mind of one skilled in the art having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is understood that the invention is not to be limited to the specific embodiments disclosed, and that modifications and embodiments are intended to be included within the scope of the foregoing description.
This application claims the benefit of U.S. Provisional Application Ser. No. 61/252,372 filed Oct. 16, 2009, the entire contents of which are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61252372 | Oct 2009 | US |
