Title:
Solar Energy Control
Kind Code:
A1


Abstract:
A solar energy collection system includes a solar concentrator operative to direct a concentrated solar beam onto a solar receptor. A shutter plate is positioned between the solar concentrator and the solar receptor and is movable from an open position adjacent to the solar beam, to a closed position wherein at least a portion of the solar beam contacts a front face of the shutter plate and is blocked from contacting the receptor. A cooling circuit is operative to circulate a cooling fluid to remove heat from the shutter plate. A shutter drive is operative to move the at least one shutter plate from the open position to the closed position, and a shutter control is operative to stop movement of the shutter plate at a plurality of locations between the open position and the closed position.



Inventors:
Tuchelt, Maurice J. (Regina, CA)
Application Number:
11/631626
Publication Date:
03/13/2008
Filing Date:
07/06/2005
Assignee:
SHEC LABS - SOLAR HYDROGEN ENERGY CORPORATION (Saskatoon, Saskatchewan, CA)
Primary Class:
International Classes:
F24J2/46; F24J2/10; F24S23/70; F24S23/71; H02S40/22
View Patent Images:



Primary Examiner:
MAGANA, SHARLA A
Attorney, Agent or Firm:
NIXON & VANDERHYE, PC (ARLINGTON, VA, US)
Claims:
1. For use in a solar energy collection system comprising a solar concentrator operative to direct a concentrated solar beam onto a solar receptor, a solar shutter apparatus adapted to be positioned between the solar concentrator and the solar receptor to selectively block a portion of the solar beam, the apparatus comprising: at least one shutter plate movable from an open position adjacent to the solar beam, to a closed position wherein at least a portion of the solar beam contacts a front face of the shutter plate and is blocked from contacting the receptor; a cooling circuit operative to circulate a cooling fluid to remove heat from the shutter plate; a shutter drive operative to move the at least one shutter plate from the open position to the closed position; and a shutter control connected to the shutter drive and operative to stop movement of the shutter plate at a plurality of locations between the open position and the closed position.

2. The apparatus of claim 1 comprising a plurality of shutter plates arranged such that the solar beam passes between the shutter plates, and wherein the shutter drive is operative to move the shutter plates toward each other to the closed position and away from each other to the open position.

3. The apparatus of claim 2 wherein the shutter plates are arranged substantially in a plane transverse to the solar beam and pivotally mounted on a shutter frame such that the solar beam passes through a central aperture formed by the shutter plates when in the open position, and wherein the drive is operative to pivot the shutter plates toward each other to the closed position to reduce a size of the central aperture.

4. The apparatus of claim 3 comprising a shutter ring rotatably mounted to the shutter frame and wherein the shutter plates are each pivotally mounted at a first portion thereof to the shutter frame and are pivotally connected at a second portion thereof to the shutter ring by a link, and wherein the drive is operative to rotate the shutter ring with respect to the shutter frame to move the shutter plates from the open position to the closed position.

5. The apparatus of claim 1 wherein solar beam is cone-shaped and decreases in diameter between the solar concentrator and the solar receptor, and wherein the at least one shutter plate defines a central aperture, and wherein the at least one shutter plate is located in proximity to the solar receptor when in the open position such that the solar beam passes through the central aperture, and is moved toward the solar concentrator to the closed position such that a portion of the solar beam contacts the at least one shutter plate adjacent to the central aperture.

6. The apparatus of claim 5 wherein the at least one shutter plate is mounted on a track aligned between the solar concentrator and the solar receptor, and wherein the drive is operative to move the at least one shutter plate along the track.

7. The apparatus of claim 1 wherein the cooling circuit comprises a cooling conduit defined by at least one shutter plate and connected to a source of cooling fluid.

8. The apparatus of claim 7 wherein the cooling conduit comprises a first hole extending from a first location on an outer edge of the at least one shutter plate to an inner end located inside the at least one shutter plate, and a second hole extending from a second location on an outer edge of the at least one shutter plate to an inner end located inside the at least one shutter plate, such that the first and second holes intersect, and such that cooling fluid circulated into the first hole flows into the second hole.

9. The apparatus of claim 8 wherein the first and second holes are located in proximity to the front face of the shutter plate.

10. The apparatus of Claim 1 wherein the front face comprises a reflective surface.

11. The apparatus of claim 1 wherein the at least one shutter plate is located in proximity to the solar receptor, and wherein a rear face of the at least one shutter plate comprises one of a reflective surface and an insulation layer such that when in the closed position the at least one shutter plate is operative to reduce heat loss from the solar receptor through the at least one shutter plate.

12. A solar energy collection system comprising: a solar concentrator operative to direct a concentrated solar beam onto a solar receptor; a shutter plate positioned between the solar concentrator and the solar receptor and movable from an open position adjacent to the solar beam, to a closed position wherein at least a portion of the solar beam contacts a front face of the shutter plate and is blocked from contacting the receptor; a cooling circuit operative to circulate a cooling fluid to remove heat from the shutter plate; a shutter drive operative to move the shutter plate from the open position to the closed position; and a shutter control connected to the shutter drive and operative to stop movement of the shutter plate at a plurality of locations between the open position and the closed position.

13. The apparatus of claim 12 comprising a plurality of shutter plates arranged such that the solar beam passes between the shutter plates, and wherein the shutter drive is operative to move the shutter plates toward each other to the closed position and away from each other to the open position.

14. The apparatus of claim 13 wherein the shutter plates are arranged substantially in a plane transverse to the solar beam and pivotally mounted on a shutter frame such that the solar beam passes through a central aperture formed by the shutter plates when in the open position, and wherein the drive is operative to pivot the shutter plates toward each other to the closed position to reduce a size of the central aperture.

15. The apparatus of claim 14 comprising a shutter ring rotatably mounted to the shutter frame and wherein the shutter plates are each pivotally mounted at a first portion thereof to the shutter frame and are pivotally connected at a second portion thereof to the shutter ring by a link, and wherein the drive is operative to rotate the shutter ring with respect to the shutter frame to move the shutter plates from the open position to the closed position.

16. The apparatus of claim 12 wherein solar beam is cone-shaped and decreases in diameter between the solar concentrator and the solar receptor, and wherein the shutter plate defines a central aperture, and wherein the shutter plate is located in proximity to the solar receptor when in the open position such that the solar beam passes through the central aperture, and is moved toward the solar concentrator to the closed position such that a portion of the solar beam contacts the shutter plate adjacent to the central aperture.

17. The apparatus of claim 16 wherein the at least one shutter plate is mounted on a track aligned between the solar concentrator and the solar receptor, and wherein the drive is operative to move the at least one shutter plate along the track.

18. The apparatus of claim 12 wherein the cooling circuit comprises a cooling conduit defined by at least one shutter plate and connected to a source of cooling fluid.

19. The apparatus of claim 18 wherein the cooling conduit comprises a first hole extending from a first location on an outer edge of the at least one shutter plate to an inner end located inside the at least one shutter plate, and a second hole extending from a second location on an outer edge of the at least one shutter plate to an inner end located inside the at least one shutter plate, such that the first and second holes intersect, and such that cooling fluid circulated into the first hole flows into the second hole.

20. The apparatus of claim 19 wherein the first and second holes are located in proximity to the front face of the shutter plate.

21. The apparatus of claim 12 wherein the front face comprises a reflective surface.

22. The apparatus of claim 12 wherein at least one shutter plate is located in proximity to the solar receptor, and wherein a rear face of the at least one shutter plate comprises one of a reflective surface and an insulation layer such that when in the closed position the at least one shutter plate is operative to reduce heat loss from the solar receptor through the at least one shutter plate.

Description:

This invention is in the field of solar energy systems and in particular controlling the energy received by a solar receptor such as a boiler, oven, or the like.

BACKGROUND

Considerable development is taking place in an attempt to efficiently and effectively harness solar energy. One typical system involves a curved mirror shaped to gather and focus solar rays into a cone-shaped focused solar beam. A solar receptor is placed near the apex of the cone and considerable heat can be generated in the receptor to perform a desired function that requires heat energy. The curved mirrors are typically made up of an array of smaller flat mirror segments arranged on a curved frame to achieve the focusing effect, and can be quite large, depending on the energy requirement of the receptor.

Such solar systems are generally placed in arid locations where the sun is reliably available so that the heat generated by the solar beam will be at least substantially consistent. The solar receptors can include boilers, thermal reactors, Stirling engines, and the like. A problem with such systems is controlling the amount of heat energy received by the solar receptor. For example a Stirling engine has no control that corresponds to a throttle whereby the energy supplied to the engine corresponds to the load. When powering a Stirling engine with solar energy from a mirror array, the solar energy supplied to the engine is substantially constant, and so the load must be maintained at a sufficient level to use all the solar energy supplied by the mirror array. If the load drops, the engine very quickly overheats and is damaged. Similar overheating and damage can occur with other solar receptors as well.

To provide a level of control, the flat mirror segments on the mirror array can be mounted such that they can be moved by an actuator. Controllers activate the actuators and pivot the mirrors to produce the focused cone-shaped solar beam. The amount of energy received by the receptor can thus be varied. Thus when overheating is detected the mirror segments are moved out of focus to reduce the amount of energy received, such as when the load on a Stirling engine drops. Such systems also allow a receptor to be heated slowly by gradually bringing the flat mirror segments into focus until the maximum or desired energy is received. The movable mirror segments, actuators, and controls are complex and so these systems are very costly to build and maintain.

It is also known to prevent damage from overheating by moving a plate into position to block the solar beam, or a portion thereof. Such plates are made from refractory materials in order to withstand the intense heat of the solar beam, and are quite fragile and subject to damage from the elements.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a solar energy control apparatus that overcomes problems in the prior art.

The present invention provides, in a first embodiment, for use in a solar energy collection system comprising a solar concentrator operative to direct a concentrated solar beam onto a solar receptor, a solar shutter apparatus adapted to be positioned between the solar concentrator and the solar receptor to selectively block a portion of the solar beam. The apparatus comprises at least one shutter plate movable from an open position adjacent to the solar beam, to a closed position wherein at least a portion of the solar beam contacts a front face of the shutter plate and is blocked from contacting the receptor. A cooling circuit is operative to circulate a cooling fluid to remove heat from the shutter plate. A shutter drive is operative to move the at least one shutter plate from the open position to the closed position, and a shutter control is connected to the shutter drive and is operative to stop movement of the shutter plate at a plurality of locations between the open position and the closed position.

The present invention provides, in a second embodiment, a solar energy collection system comprising a solar concentrator operative to direct a concentrated solar beam onto a solar receptor. A shutter plate is positioned between the solar concentrator and the solar receptor and is movable from an open position adjacent to the solar beam, to a closed position wherein at least a portion of the solar beam contacts a front face of the shutter plate and is blocked from contacting the receptor. A cooling circuit is operative to circulate a cooling fluid to remove heat from the shutter plate. A shutter drive is operative to move the at least one shutter plate from the open position to the closed position, and a shutter control is connected to the shutter drive and is operative to stop movement of the shutter plate at a plurality of locations between the open position and the closed position.

The present invention provides a solar control apparatus that prevents a portion of a focused solar beam from contacting a solar receptor. The apparatus comprises a shutter movable from an open position, where the complete solar beam hits the solar receptor, to a closed position wherein at least a portion of the solar beam is blocked and prevented from hitting the solar receptor. The apparatus can comprise one or more shutter plates, each having a cooling conduit defined in an interior thereof, and a source of cooling fluid connected to circulate through the cooling conduit to remove heat from the shutter plate. The circulating cooling fluid removes the considerable amounts of heat generated in the shutter plates, and dissipates same in a location remote from the shutter plates, such as though a radiator or the like.

The present invention provides a shutter apparatus adapted to be positioned between a solar concentrator, such as a curved mirror, that is operative to focus solar rays into a focused solar beam, and a solar receptor that is oriented to receive the focused solar beam. The solar receptor will typically be a reaction chamber, Stirling engine, or the like and the curved mirror will be provided by an array of mirror segments.

In one embodiment, the shutter apparatus comprises a plurality of shutter plates pivotally mounted to a shutter frame, and a shutter control operative to move the shutter plates from an open position, where the complete solar beam hits the solar receptor, to a plurality of partially closed positions wherein varying portions of the solar beam are blocked and prevented from hitting the solar receptor, and then to a closed position where the solar beam is substantially blocked. Each shutter plate includes an internal cooling conduit and a source of cooling fluid is connected to each cooling conduit such that cooling fluid circulates through the cooling conduits to remove heat from the shutter plates.

In a second embodiment the shutter apparatus comprises an annular shutter plate defining a central aperture. Again the annular shutter plate includes one or more internal cooling conduits and a source of cooling fluid is connected to the cooling conduits such that cooling fluid circulates through the cooling conduits to remove heat from the annular shutter plate. The annular shutter plate is mounted transversely to the solar beam. When the annular shutter plate is located close to the solar receptor, the complete solar beam can pass through the central aperture and hit the solar receptor. As the annular shutter plate is moved away from the solar receptor toward the curved mirror the outer portion of the cone-shaped solar beam hits the annular shutter plate and is thus prevented from hitting the solar receptor. Due to the conical shape of the beam, the annular shutter plate can be wide enough that when located a considerable distance from the solar receptor, the great majority of the solar beam is blocked, with only a small portion passing through the central aperture to hit the solar receptor. In this embodiment a linear shutter control controls the distance between the annular shutter plate and the solar receptor.

The cooling fluid could conveniently and effectively be a mixture of water and glycol such as is used in engine cooling systems. Such a mixture pumped in large volumes has the ability to remove a large amount of heat from the shutter plates, and is safe and convenient to handle. It is contemplated that other fluids, both liquid and gaseous, could be used as cooling fluids as well.

It is also contemplated that the shutter plates could be insulated or reflective on a rear surface thereof facing the solar receptor. Then during periods of cloud or at night, the shutter plates could be closed and heat would be retained in the solar receptor rather than radiating out through the opening in the shutter apparatus.

DESCRIPTION OF THE DRAWINGS

While the invention is claimed in the concluding portions hereof, preferred embodiments are provided in the accompanying detailed description which may be best understood in conjunction with the accompanying diagrams where like parts in each of the several diagrams are labeled with like numbers, and where:

FIG. 1 is a schematic side view of a shutter apparatus of the invention set up between a solar concentrator, schematically illustrated as a curved mirror, and a solar receptor where the shutter apparatus is in the open position with all of the solar beam being received by the solar receptor;

FIG. 2 is a schematic side view of an embodiment of the shutter apparatus of FIG. 1 with shutter plates that are moved toward each other to a partially closed position with only a portion of the solar beam being received by the solar receptor;

FIG. 3 is a schematic side view of an alternate embodiment of the shutter apparatus of FIG. 1 with an annular shutter plate showing the shutter apparatus moved toward the solar concentrator to a partially closed position with only a portion of the solar beam being received by the solar receptor;

FIG. 4 is a perspective rear view of a shutter apparatus comprising pivoting shutter plates such as could be used in the embodiment of FIG. 2 showing the shutter plates in the open position;

FIG. 5 is a perspective front view of the shutter apparatus of FIG. 4 showing the shutter plates in the open position;

FIG. 6 is a perspective rear view of the shutter apparatus of FIG. 4 showing the shutter plates in partially closed position;

FIG. 7 is a perspective front view of the shutter apparatus of FIG. 4 showing the shutter plates in an almost fully closed position, and also showing a shield plate installed to protect the shutter control mechanism;

FIG. 8 is a schematic perspective rear view showing the internal cooling conduit in one of the shutter plates;

FIG. 9 is a front view of an alternate annular shutter plate such as would be used in the shutter apparatus of FIG. 3;

FIG. 10 is a schematic illustration of the operation of the shutter apparatus of FIG. 10.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

FIG. 1 schematically illustrates a shutter apparatus 2 of the invention set up between a solar concentrator, illustrated as a curved mirror 4, and a solar receptor 6 such as are known in the prior art. The curved mirror 4 focuses solar rays into a cone-shaped solar beam 8, and the solar receptor 6 is positioned substantially at the apex of the cone to receive the solar beam 8. The heat generated by the solar beam 8 in the solar receptor 6 is used in various ways as are well known in the art.

In FIG. 1, the shutter apparatus 2 is shown in the open position where all of the solar beam passes through the shutter apparatus and is received by the solar receptor 6. FIG. 2 schematically illustrates the operation of an embodiment of the shutter apparatus 2 that uses a plurality of movable shutter plates to block the solar beam 8 and prevent varying portions thereof from hitting the solar receptor 6. FIG. 2 illustrates the shutter apparatus 2 in a partially closed position with only a portion of the solar beam 8 being received by the solar receptor 6.

An embodiment of a shutter apparatus 2 is illustrated in FIGS. 4-8 that fairly evenly controls the solar energy received by the solar receptor 6. The shutter plates 10 are pivotally mounted at one corner thereof to a shutter frame 12 and define a central aperture 14. The shutter plates 10 are also pivotally connected at another corner thereof via links 20 to a shutter ring 16 that rotates with respect to the shutter frame 12 in response to rotation of a drive motor 18. Thus the shutter plates 6 can pivot from the open position of FIGS. 4 and 5, through the partially closed position of FIG. 6, and through the more fully closed position of FIG. 7 to a substantially completely closed position.

It can thus be seen that as the shutter plates 6 move from the open position to the closed position, varying portions of the solar beam 8 will be blocked and prevented from hitting the solar receptor 6. The heat energy received by the solar receptor 6, and thus the temperature thereof, can be thus be finely controlled by activating the drive motor 18 to open or close the shutter plates 10. As can be seen, unlike a camera shutter, the shutter plates 10 do not overlap. The solar beam 8 can pass between the edges of the shutter plates 10, as well as through the center of the central aperture 14. FIG. 7 illustrates the front of the shutter apparatus 2 that faces the curved mirror 4 with a shield plate 21 installed to protect the shutter mechanism. The illustrated embodiment thus closes off the conical solar beam 8 from all sides thereof at once, such that the remaining portion of the solar beam 8 received by the solar receptor 6 is substantially evenly distributed on the face of the solar receptor 6, resulting in substantially even heating of the receptor.

While the particular arrangement illustrated is simple and convenient and results in even heating of the solar receptor 6, it is contemplated that other arrangements would also serve the purpose of moving the shutter plates 10 in and out of the solar beam 8 to block reception by the solar receptor 6. Such a shutter apparatus could be provided for example by positioning a pair of shutter plates adjacent to each side of the beam 8 and moving them together or apart to block or not block the beam 8. Such other arrangements are therefore contemplated to fall within the scope of the invention.

FIG. 8 schematically illustrates in one shutter plate 10 an internal cooling conduit 22 that is defined in the interior of each shutter plate 10. The shutter plates 10 are quite thick, and the cooling conduit 22 is provided quite simply in the illustrated embodiment by drilling a pair of holes 24 from the outer edge of the shutter plate 10 on an angle toward the inner ends thereof. The holes 24 meet near their inner ends and thus form the cooling conduit 22 where cooling fluid flowing into one hole will also flow into the other hole. Hose barbs 26 are attached to the exposed ends of the holes 24 to facilitate connection of the cooling conduit 22 to a cooling fluid source 28. A cooling fluid, such as a water-glycol mixture, air, or the like is circulated from the cooling fluid source 28 through the cooling conduit 22.

The holes 24 are sized and positioned such that they pass quite close to the surface of the shutter plate 10 to quickly draw heat away from the surface. The shutter plates are made from material that conducts heat well and also withstands exposure to the elements. Aluminum provides a good material for the shutter plates 10, however other materials such as copper could also be used. The front face of the shutter plates 10, facing the curved mirror 4, could also be polished to reflect the solar beam 8 such that less heat is absorbed that must be removed by the cooling fluid.

Further, where the shutter apparatus 2 is located closely adjacent to the solar receptor 6 as in FIGS. 1 and 2, the shutter plates 10 could be insulated or reflective on a rear surface thereof facing the solar receptor 6. Then during periods of cloud or at night, the shutter plates 10 could be closed and heat would be retained in the solar receptor 6 rather than radiating out through the central aperture 14 and being lost.

FIG. 9 schematically illustrates an alternate shutter apparatus 102, suitable for use as illustrated in FIGS. 3 and 10. The shutter apparatus 102 comprises an annular shutter plate 110. One or more internal cooling conduits 122 are defined in the annular shutter plate 110 in a similar manner to that described above and are connected to a cooling fluid source. The annular shutter plate 110 is again made from heat conductive material to facilitate removal of heat by cooling fluid circulating through the cooling conduits 122.

As illustrated in FIG. 10 when the annular shutter plate 110 is located in position A, close to the solar receptor 6, all of the solar beam 8 passes through the central aperture 114 and hits the solar receptor 6. The annular shutter plate 110 is mounted on a track or the like such that the drive can move the shutter plate 110 toward or away from the solar receptor 6. As the annular shutter plate 110 moves away from the solar receptor 6 the outer portions of the conical solar beam 8 are blocked by the annular shutter plate 110. In position B, a small portion of the solar beam 8 is blocked, while at position C a very large portion of the solar beam 8 is blocked.

While the particular arrangements illustrated are simple and convenient, it is contemplated that other arrangements would also serve the purpose of moving the shutter plates 10, 110 in and out of the solar beam 8 to block reception by the solar receptor 6, and such other arrangements are contemplated to fall within the scope of the invention.

Thus the foregoing is considered as illustrative only of the principles of the invention. Further, since numerous changes and modifications will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly, all such suitable changes or modifications in structure or operation which may be resorted to are intended to fall within the scope of the claimed invention.