US20090223510A1

US20090223510A1 - Optimized solar collector

Info

Publication number: US20090223510A1
Application number: US12/425,965
Authority: US
Inventors: Theodore E. Larsen
Original assignee: Individual
Current assignee: Individual
Priority date: 2006-11-22
Filing date: 2009-04-17
Publication date: 2009-09-10

Abstract

A solar collector has articulated first and second reflective panel operably connected to a rotatable pivot housing defining an interior channel that can be filled with a fluid for storing heat generated by the reflection of solar radiation. The solar collector may also include a system for collecting an recycling water that can be used to fill the interior channel or clean the surface of the first reflective panel. The first and second reflective panels are generally shiftable into a parabolic configuration defining a focus line spaced apart from a reflector formed by the first and second panels.

Description

RELATED APPLICATIONS

The present application is a Continuation-In-Part of application Ser. No. 11/986,417, filed Nov. 21, 2007, entitled ADJUSTABLE SOLAR COLLECTOR AND METHOD OF USE, which claims the benefit of U.S. Provisional Application No. 60/860,623, entitled ADJUSTABLE SOLAR COLLECTOR AND METHOD OF USE, filed Nov. 22, 2006, both of which applications are hereby fully incorporated herein by reference in their entirety.

FIELD OF THE INVENTION

The present invention relates generally to solar energy collection devices and more, specifically, to parabolic trough solar collectors.

BACKGROUND OF THE INVENTION

With increases in the cost of fossil fuels and a rise in public awareness of the environmental consequences of current fuel consumption habits, the demand for alternative, renewable energy sources is growing. One such renewable energy source is solar energy. It is estimated that approximately 99.9% of harvestable renewable energy is solar-based, which includes resources such as wind, wave power, hydroelectricity, biomass, and solar power.
Solar energy can be most useful when converted into another form. In many instances, solar energy is ultimately converted into electricity. A number of devices and methods are known for converting solar energy into electricity. These technologies can generally be characterized as active or passive and as direct or indirect solar energy-conversion systems. Active systems typically rely upon electrical and mechanical components to capture short-wavelength radiation in the form of sunlight and convert it into a usable form. Passive systems rely upon non-mechanical techniques to control the capture of sunlight and convert this energy into a usable form. Passive techniques include referencing the position of a building to the sun to enhance energy capture, designing spaces that naturally circulate air to transfer energy, and selecting materials with favorable thermal properties to absorb and retain energy. Direct systems typically convert sunlight into a usable form of energy in a single step. Indirect systems typically convert sunlight into a usable form of energy through multiple steps.
One way to actively convert solar energy into a usable form of energy is through the use of Concentrating Solar Thermal (CST) systems. Concentrating Solar Thermal systems generally rely upon a shaped reflective surface, known as a solar collector or solar concentrator, to concentrate sunlight. Solar concentrators receive solar radiation over a relatively large surface area and focus it on a relatively small surface. More specifically, solar concentrators use lenses or mirrors to focus a large area of sunlight into a small beam or plane. Most CST systems also incorporate tracking systems that allow lenses or mirrors to follow the path of the sun. Four common types of CST systems are the solar power tower, the parabolic dish, the solar bowl, and the solar trough.
Many types of solar troughs are well-known in the art. Examples of solar troughs are described in the following issued patents and printed publications, the disclosures of which are incorporated herein by reference in their entirety: U.S. Pat. No. 4,099,515 to Schertz; U.S. Pat. No. 4,243,019 to Severson; U.S. Pat. No. 4,296,737 to Silk; U.S. Pat. No. 4,313,422 to McEntee; U.S. Pat. No. 4,423,719 to Hutchinson; U.S. Pat. No. 4,493,313 to Eaton; U.S. Pat. No. 4,546,757 to Jakahi; U.S. Pat. No. 6,276,359 to Frazier; U.S. Pat. No. 6,832,608 to Barkai, et al.; U.S. Pat. No. 6,886,339 to Carroll, et al; U.S. Pat. No. 7,055,519 to Litwin; U.S. Pub. No. 2007/0034207 to Niedermeyer; U.S. Pub. No. 2007/0223096 to O'Connor, et al., and U.S. Publication No. 2007/0240704 to Prueitt.
Parabolic troughs generally have a long parabolic mirror with a tube, also known as a receiver, running the length at the focal point of the mirror. The receiver is filled with a fluid, such as, for example, water or oil. To maximize the reflectivity of the trough, the top surface of the mirror is usually provided with a silver coating or polished aluminum. Due to the parabolic shape of the mirror, the trough is able to concentrate reflected sunlight onto the receiver. The concentrated sunlight heats the fluid flowing through the receiver. Depending upon the type of fluid being used and the particular design of the trough, the temperature of the fluid can exceed 400° C. When the trough is incorporated as part of a CST system, the heated fluid is transferred to a power generation system and used to generate electricity. The process can be economical and can achieve thermal efficiency in the range of approximately sixty to eighty percent.
Parabolic troughs can occupy a fixed position or be adjustable. Since the amount of solar radiation reflected to the receiver largely depends on the angle of the sun in relation to the trough, the position of the trough in relation to the sun greatly affects the ability of the reflective surface to concentrate sunlight onto the receiver. When the sun is at a sharp angle in relation to the trough, such as in the early morning or late afternoon, the amount of insolation or incoming solar radiation that can be captured by a parabolic concentrator oriented to capture insolation when the sun is higher in the sky may be relatively low. Therefore, adjustable parabolic troughs are generally more effective and are preferred in the industry. Adjustable troughs can be designed to adjust their position with respect to the sun in various ways. For example, an adjustable trough can incorporate a sun-rotating mechanism that tracks the course of the sun.
Parabolic troughs that have the ability to track the sun are generally constructed so that their axis of rotation is parallel to the path of the sun as it moves across the sky. Current technology provides for continual automatic adjustment of the troughs that is coordinated with the sun's movement. Movement of the troughs in response to the changing position of the sun is generally accomplished through adjustments along an axis perpendicular to the axis of the troughs. Though east-west or north-south orientation of the collector axis is typically specified for year-round or summer-peaking sunlight collection, respectively, troughs can be oriented in any direction. The arrangement of troughs in parallel rows simplifies system design and field layout, and minimizes interconnecting piping. Parabolic troughs can also be mounted on the ground or on a roof.
Some solar collectors also have the ability to reflect short-wavelength solar radiation back into space. For example, U.S. Pat. No. 5,177,977 discloses a parabolic trough that can be defocused so that some of the short-wavelength radiation arriving at the mirrored surface of the collector is randomly directed back into space. A drawback of this feature, however, is the difficulty of interchanging between the configuration needed to concentrate sunlight onto a receiver and the configuration needed to redirect short-wavelength radiation back into space. In addition, there is a need to increase the efficiency of the redirection of short-wavelength radiation by parabolic troughs.
Since parabolic troughs depend upon a mirrored surface to concentrate reflected sunlight, environmental conditions that may reduce the reflectivity of the mirrored surface are of great concern. For example, inclement weather, dust, and wildlife can leave unwanted deposits on the inner surface of the trough that reduces the ability of the trough to reflect sunlight. To reduce the likelihood of damage to or dirtying of the reflective inner surface, some troughs can be rotated so as to achieve an inverted position. In the inverted position, the mirrored surface can be substantially shielded from hazards such as hail, dust, and other particulate matter. A drawback of these inversion capabilities, however, is that the parabolic shape of the trough requires the trough to be elevated high above the ground (or other mounting surface) so that edges of the parabolic structure will not strike the ground (or other mounting surface) when rotated or inverted. Specifically, building a support structure that is tall enough to accommodate inversion can substantially increase burdens associated with installing and placing solar concentrators to be elevated. Existing parabolic troughs also lack an effective and efficient way to clean deposited material or films from the mirrored surfaces.
In addition to the mirrored surfaces of parabolic troughs, the structure of the parabolic trough as a whole can be susceptible to damage by environmental forces such as high winds. Current construction techniques for building solar concentrators generally utilize materials having a high stiffness and that are rigidly joined together to form an uninterrupted parabolic trough. While this type of construction contributes to an efficient collection of sunlight, it can also lead to catastrophic damage or fatigue that ultimately results in failure. Specifically, the parabolic face of the trough acts as a wind barrier that places tremendous strain on the solar concentrator structure during periods of high wind. A procedure for reducing wind strain on the structure is to invert the parabolic shape of the solar collector. As with protecting the solar collector from deposits on the mirrored surface, a disadvantage of inverting the parabolic shape is that the trough must be sufficiently elevated above the ground (or other mounting surface) so that edges of the parabolic structure will not strike the ground (or other mounting surface) when rotated or inverted. Even when the parabolic shape of the solar collector is inverted, pressure differentials created by the movement of air over the inverted solar collector can produce structural strain that can reduce the life expectancy of the structure. In addition, while an elevated support structure may accommodate an inverted position, the increased height further destabilizes the structure.
Due to a variety of factors, parabolic solar collectors are commonly found in arid climates where water is scarce. In particular, it can be advantageous to construct a number of solar collectors in a single location. This may require large, open areas of flat land that are located far from population centers and may not otherwise provide opportunities for economically viable activities. It can also be advantageous to construct solar collectors in locations that dependably receive large amounts of direct sunlight and experience relatively constant lengths of days throughout the year. Since desert locations commonly meet these criteria and can be relatively inexpensive to purchase, solar collectors are often constructed in dry, drought-prone clients.
As a result of this tendency, a lack of available water can be a major concern. For example, it is often necessary to clean off the mirrored surfaces of the parabolic solar collectors in order to increase their reflective capabilities, thereby also enhancing their ability to generate electricity. Without sufficient water, therefore, the performance of parabolic solar collectors can be severely diminished.
Parabolic solar collectors can also be constructed in regions where water is more plentiful or rainfall is concentrated during certain times of year. In such areas and instances, it may be beneficial to collect such water. The water can then be diverted for specific uses, such as agriculture, or stored for later use when water is less plentiful.
A further drawback of parabolic collectors is providing energy for use during periods of indirect sunlight or non-daylight hours. During such times, a lack of solar radiation limits the ability of parabolic solar collectors to create mechanical or thermal energy. As a result, the electrical energy that can be supplied solar collectors is often asymmetrical and sporadic. This limits the use of parabolic solar collectors as a primary source for fulfilling electricity needs. Based on the demands for power consumption, there is a need for a parabolic solar collector that can provide a source for the generation of electricity during periods in which direct solar radiation may not be available.
Therefore, there remain opportunities to further improve upon current designs. What is needed in the industry is a parabolic solar collector that improves upon the aforementioned drawbacks.

SUMMARY OF THE INVENTION

The concerns described above are overcome in substantial part by the present invention. A parabolic collector is formed from a plurality of sections flexibly connected through a hinge arrangement attached on a line tangent with what is effectively the trough axis. This allows the reflective surfaces to be positioned so that they form a continuous parabolic surface in a first position, while also being positionable in other positions. For example, a “clamshell” structure may be achieved by folding the sections together. When closed, the structure may be aligned in various orientations. In a second position, the folded structure is oriented generally perpendicular to the mounting surface. In a third position, the folded structure is oriented generally parallel to mounting surface. Because of the parabolic shape of the sections, the folded structure may be oriented to present a plurality of aerodynamic surfaces. When oriented generally parallel to a wind force, the structure presents an upper curved surface that tends to provide an upward lift while the structure's lower curved surface tends to provide a downward force. The generally horizontal net wind load thus applies a force on the reduced horizontal profile presented by the folded structure. Moreover, the vertical wind forces on the upper and lower curved surfaces of the structure tend to offset each other.
In an embodiment, a solar collector for concentrating solar radiation comprises a substantially parabolic reflector, a pivot housing, a first conduit, a second conduit, a control valve, a reservoir system, and a reservoir valve. The substantially parabolic reflector defines a focus line spaced apart from the reflector and has a first mirrored surface adapted to reflect the solar radiation to the focus line. The pivot housing is operably coupled to the substantially parabolic reflector and defines a substantially enclosed sealable interior channel and an axis of rotation. The pivot housing is positioned substantially proximal the vertex of the substantially parabolic reflector. The solar collector is shiftable about the axis of rotation. The first conduit is positioned substantially along the focus line of the substantially parabolic reflector. The second conduit is positioned within the pivot housing. The conduit valve operably couples the first fluid conduit and the second fluid conduit such that the first fluid conduit and the second fluid conduit are in interruptable fluid communication. The reservoir system is adapted to contain a fluid that can be sealed within the interior channel of the pivot housing. The reservoir valve operably couples the interior channel of the pivot housing and the reservoir system such that the interior channel and the reservoir system are in interruptable fluid communication.
In further embodiments, the substantially parabolic reflector may include articulated first and second reflective panels operably shiftably coupled to the pivot housing. The first and second reflective panels may be reversibly shiftable between a folded position and an open position. The first and second reflective panels may form a substantially parabolic shape intermediate the folded position and the open position. The reservoir system may include a storage section, a delivery section, and an actuatable coupling valve for selectively coupling the storage section to the delivery section. The storage section may be in fluid communication with the delivery section when the actuatable coupling valve is actuated. The pivot housing may be freely rotatable when the actuable coupling valve is not actuated. The solar collector may further include a pump for creating an increase in fluid pressure in the storage section of the reservoir system. The increase in fluid pressure may cause the actuatable coupling valve to couple the storage section with the delivery section. The interior channel of the pivot housing may define a substantially sealed environment when the reservoir valve is closed. The second conduit may include a coiled region.
In an embodiment, a solar collector for concentrating solar radiation includes a substantially parabolic reflector, a pivot housing, a cleaning system, a reservoir system, and a drainage system. The substantially parabolic reflector defines a focus line and a vertex. The substantially parabolic reflector presenting a first mirrored surface for reflecting the solar radiation to the focus line. The pivot housing is operably coupled to the substantially parabolic reflector and defines a substantially enclosed sealable interior channel and an axis of rotation. The pivot housing is positioned substantially proximal the vertex of the substantially parabolic reflector. The solar collector is shiftable about the axis of rotation. The cleaning system applies a fluid to the first mirrored surface. The reservoir system is adapted to communicate the fluid to the cleaning system. The drainage system communicates fluid collected by the first reflective panel to the reservoir system.
In further embodiments, the substantially parabolic reflector may include articulated first and second reflective panels operably shiftably coupled to the pivot housing. The first and second reflective panels may be reversibly shiftable between a folded position and an open position. The first and second reflective panels may form a substantially parabolic shape intermediate the folded position and the open position. The reservoir system may comprise a storage section, a delivery section, and an actuatable coupling valve for selectively coupling the storage section to the delivery section. The storage section may be in fluid communication with the delivery section when the actuatable coupling valve is actuated. The pivot housing may be freely rotatable when the actuable coupling valve is not actuated. The solar collector may further include a plurality of nozzles adapted to spray the fluid onto the first mirrored surface of the reflector when the first and second reflective panels are shifted into a closed positioned. The first mirrored surface of the substantially parabolic reflector, the cleaning system, the reservoir system, and the drainage system may define a substantially closed system such that the fluid can be applied to the first mirrored surface and circulated through the cleaning, reservoir, and drainage systems in multiple cycles. The substantially parabolic reflector may define a second surface. The second surface may be coated with a substantially hydrophilic material for facilitating condensation of moisture on the second surface. The first and second reflective panels may be shiftable such that the moisture is gravitationally communicated to the drainage system. The solar collector may further include a pump for creating an increase in fluid pressure in the storage section of the reservoir system. The increase in fluid pressure may cause the actuatable coupling valve to couple the storage section with the delivery section.
In an embodiment, a method of collecting solar radiation from a solar collector includes communicating a first fluid from a reservoir system to the interior channel of a pivot housing, substantially sealing the fluid within the interior channel of the pivot system, reflecting solar radiation with a first reflective panel toward a focus line, receiving the solar radiation with a first conduit positioned at the focus line, communicating a second fluid from the first conduit to a second conduit positioned within an interior channel of a pivot housing, and transferring heat from the second fluid to the first fluid. The solar collector includes the substantially parabolic reflector, a pivot housing, and a reservoir system. The substantially parabolic reflector defines a focus line spaced apart from the reflector and has a first mirrored surface adapted to reflect the solar radiation to the focus line. The pivot housing defines an interior channel. The reservoir system is adapted to communicate fluid to the interior channel of the pivot housing.
In further embodiments, the method may include evacuating the second fluid from the second conduit, re-communicating the second fluid into the second conduit, transferring heat from the first fluid to the second fluid, and converting the heat into electricity in the absence of reflection of the solar radiation by the substantially parabolic reflector. The method may also include evacuating the interior channel of the pivot housing of the first fluid.
In an embodiment, a method of cleaning a solar collector includes communicating a fluid from a first mirrored surface of a substantially parabolic reflector to a fluid drainage system, communicating the fluid from the fluid drainage system to a reservoir system, communicating the fluid from the reservoir system to a cleaning system, and applying the fluid to the reflective surface of the first mirrored surface of the substantially parabolic reflector. The solar collector includes the substantially parabolic reflector, the pivot housing, the drainage system, the reservoir system. The substantially parabolic reflector defines a focus line spaced apart from the reflector and has a first mirrored surface adapted to reflect the solar radiation to the focus line. The pivot housing defines an interior channel.
In further embodiments, communicating the fluid from the first mirrored surface of the substantially parabolic reflector to the fluid drainage system includes collecting the fluid in a drainage trough. The fluid may be rainwater. The substantially parabolic reflector may include a second surface coated with a substantially hydrophilic material for facilitating condensation of moisture on the second surface. The method may further include facilitating the condensation of water on the second surface of substantially parabolic reflector and communicating the water from the second surface of the substantially parabolic panel to the drainage system. The method may also include converting a portion of the fluid within the interior channel of the pivot housing into steam and pressurizing the first fluid within the interior channel of the pivot housing. Pressurizing the first fluid may include increasing a pressure within the interior channel of the pivot housing to approximately 1,000 psi. The method may additionally include releasing the first fluid from the interior channel through explosive actuation. The method may include neutralizing pressure depressions caused by severe weather conditions. The method may include stabilizing pressure increases due to fuel deflagrations.
In an embodiment, a solar collector for concentrating solar radiation includes a substantially parabolic reflector, a pivot housing, a first conduit, a second conduit, a conduit valve, a reservoir system, a cleaning system, a reservoir system, a drainage system, and a reservoir valve. The substantially parabolic reflector may define a focus line spaced apart from the reflector and have a first mirrored surface adapted to reflect the solar radiation to the focus line. The pivot housing may be operably coupled to the substantially parabolic reflector. The pivot housing may define a substantially enclosed sealable interior channel and an axis of rotation. The pivot housing is further positioned substantially proximal the vertex of the substantially parabolic reflector. The solar collector is shiftable about the axis of rotation. The first conduit is positioned substantially along the focus line of the substantially parabolic reflector. The second conduit is positioned within the pivot tube. The conduit valve operably couples the first fluid conduit and the second fluid conduit such that the first fluid conduit and the second fluid conduit are in interruptable fluid communication. The reservoir system is adapted to contain a fluid that can be sealed within the interior channel of the pivot housing. The cleaning system applies a second fluid to the first mirrored surface of the substantially parabolic reflector. The reservoir system is adapted to communicate the second fluid to the cleaning system. The drainage system communicates fluid collected by the substantially parabolic reflector to the reservoir system. The reservoir valve operably couples the interior channel of the pivot housing and the reservoir system such that the interior channel and the reservoir system are in interruptable fluid communication.
In further embodiments, the substantially parabolic reflector may include articulated first and second reflective panels operably shiftably coupled to the pivot housing. The first and second reflective panels may be reversibly shiftable between a folded position and an open position. The first and second reflective panels may form a substantially parabolic shape intermediate the folded position and the open position.
Exemplary embodiments of the invention are explained in greater detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments of the present invention may be more completely understood in consideration of the following detailed description of various embodiments of the invention in connection with the accompanying drawings, in which:

FIG. 1 is a perspective view of a solar collector according to a known embodiment;

FIG. 2 is a perspective view of a plurality of solar collectors according to a known embodiment;

FIG. 3 is a perspective view of a solar collector according to a known embodiment;

FIG. 4 is a schematic illustration of a CST system integrated into a power grid;

FIG. 5 is a perspective view of a solar collector according to an embodiment of the present invention;

FIG. 6 is a perspective view of a solar collector according to an embodiment of the present invention;

FIG. 7 is a perspective view of a solar collector according to an embodiment of the present invention;

FIG. 8 is a perspective view of a solar collector according to an embodiment of the present invention;

FIG. 9 is a perspective view of a solar collector according to an embodiment of the present invention;

FIG. 10 is perspective view of a solar collector according to an embodiment of the present invention;

FIG. 11 is a perspective view of rotating and folding mechanisms of a solar collector according to an embodiment of the present invention;

FIG. 12 is a perspective view of a rotating mechanism of a solar collector according to an embodiment of the present invention;

FIG. 13 is a cross-sectional view of solar collector according to an embodiment of the present invention;

FIG. 14 is a perspective illustration of a parabolic trough formed by a solar collector according to an embodiment of the present invention;

FIG. 15A is a cross-sectional illustration of a parabolic trough formed by a solar collector according to an embodiment of the present invention;

FIG. 15B is a cross-sectional illustration of a parabolic trough formed by a solar collector according to an embodiment of the present invention;

FIG. 16 is a cross-sectional illustration of a parabolic trough according to an embodiment of the present invention;

FIG. 17 is a cross-sectional illustration of a parabolic trough according to an embodiment of the present invention;

FIG. 18 is cross-sectional illustration of a parabolic trough according to an embodiment of the present invention;

FIG. 19 is a partial cross-sectional view of a solar collector according to an embodiment of the present invention;

FIG. 20 is a partial cross-section view of a solar collector according to an embodiment of the present invention showing elected cut-away sections;

FIG. 21 is a cross-sectional view of a heat reservoir system of a solar collection system according to an embodiment of the present invention; and

FIG. 22 is a schematic view of a fluid delivery system of a solar collector according to an embodiment of the present invention.

While the present invention is amendable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit the present invention to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

A solar collector is depicted generally in FIG. 1 with reference numeral 100. As with other solar collectors known in the existing art, solar collector 100 comprises parabolic mirror 102, tube 104, rotating mechanism 106, and support structure 107, as depicted generally in FIGS. 1-3. Referring to FIG. 5, solar collector 100 also generally comprises folding mechanism 108 and self-cleaning mechanism 110. A plurality of solar collectors 100 can be operably combined to form part of CST System 112, as depicted in FIG. 4. Solar collector 100 can generally reflect short-wavelength radiation λ toward tube 104, as depicted in FIG. 3.
Referring to FIGS. 5-6, parabolic mirror 102 comprises curved panels 114, 116 and hinge mechanism 118. In the embodiment of solar collector 100 shown in FIGS. 5-6, solar collector 100 has two panels 114, 116 forming a trough characterized by a rigid, substantially parabolic form. Any number of panels, however, could be used to form a solar collector 100 without departing from the spirit or scope of the present invention. The number of panels used may depend in part on the degree to which independent movement of the panels is desired by a designer or user of system 112.
Each panel 114, 116 have inside surface 120 and outside surface 122. In an example embodiment, inside surface 120 reflects sunlight, while outside surface 122 primarily provides structural support. Although inside and outside surfaces 120, 122 may be made from the same material, inside and outside surfaces 120, 122 are generally made from different materials. Inside surface 120 may, for example, be made from silver foil, coated silver, or polished aluminum, while outside surface may be made from steel. Outer surface 122 may be coated with a hydrophilic material, according to an embodiment of the present invention
Panels 114, 116 may be any number of shapes and sizes. In an example embodiment, panels 114, 116 are shaped so as to be able to form a parabolic trough, as depicted in FIGS. 5-6 and 13. Panel 114 is generally constructed so to be substantially the same shape and size as panel 116. Therefore, panels 114, 116 are substantially mirror images of each other.
Panels 114, 116 are operably connected to hinge mechanism 118. In an example embodiment, hinge mechanism 118 is attached to outside surfaces 122 of panels 114, 116. Hinge mechanism 118 is adapted to permit panels 114, 116 be folded into a closed position, as depicted in FIGS. 7-9 and 16-17. Hinge mechanism 118 also permits panels 114, 116 to be unfolded into open position, as depicted in FIGS. 10 and 18. Hinge mechanism 118 can also hold panels 114, 116 together so that panels 114, 116 substantially form a continuous, substantially parabolic surface. To provide rotational clearance for the inner edges of panels 114, 116 during folding and unfolding, hinge mechanism 118 provides for gap 124 between panels 114, 116. Gap 124 ensures that panels 114, 116 do not interfere with each other while solar collector 100 is opened and closed.
Substantially covering gap 124 is self-cleaning system 110. Self-cleaning system 110 is depicted generally in FIGS. 5-6. Self-cleaning system 110 generally comprises reflective plate 126, nozzles 128, and collection mechanism (not shown). Reflective plate 126 houses nozzles 128 and reflects short-wavelength radiation λ. The reflective surface of reflective plate 126 is generally made from the same or similar materials as the reflective inner surfaces 120 of panels 114, 116, such as, for example, silver foil, coated silver, or polished aluminum. Although reflective plate 116 may be any number of shapes and sizes, the reflective plate 126 generally parabolically corresponds with panels 114, 116. In an example, embodiment, with reflective panel 126 over gap 124, panels 114, 116 can be positioned so that panels 114, 126 and reflective panel 126 substantially form a parabolic trough, as depicted in FIGS. 5-6.
Referring to FIGS. 5-6, nozzles 128 are generally positioned at systematic intervals and are adapted to spray a cleaning fluid. Nozzles 128 may exhibit any number of spray patterns. In an example embodiment, nozzles 128 generally exhibit a spray pattern capable of cleaning the inner surfaces 120 of panels 114, 116 when panels 114, 116 are folded into a closed position, as depicted in FIGS. 7-9. A collection mechanism (not shown) can be located underneath gap 124. The collection mechanism receives cleaning fluid falling through gap 124 and can redirect the cleaning fluid to nozzles 128.
Referring to FIGS. 5-10, solar collector 100 has tube 104. Tube 104 is generally positioned above reflective plate 126, as depicted in FIG. 5-10, and is adapted to accommodate the flow of fluid. In an example embodiment, tube 104 is positioned along focal line 136 of the parabolic trough that can be formed by panels 114, 116. In an example embodiment, tube 104 is made from or coated with a material that facilitates the absorption of short-wavelength radiation λ. For example, tube 104 may be painted black or coated with black chrome. Referring to FIG. 3, a plurality of tubes 104 can be interconnected to form part of CST system 112.
As previously described, panels 114, 116 and reflective plate 126 can be positioned so that solar collector 100 forms a parabolic trough. Referring to FIG. 13, panels 114, 116 and reflective plate 126 can form parabola 130 in cross section. Parabola is characterized by focal point 132 and vertex 134. Referring to the perspective view of parabolic solar collector 100 depicted in FIG. 13, solar collector 100 has focal line 136 running the length of panels 114, 116. In an example embodiment, tube 104 is located at and substantially follows focal line 136.
Solar collector 100 has folding mechanism 108, as depicted in FIGS. 8-9 and 11. Folding mechanism 108 may be any number of mechanisms that allow panels 114, 116 to be folded and unfolded between closed and open positions. In an example embodiment, folding mechanism 118 comprises torque tube 138, drive train 140, lift arm 142, and motor 144. Torque tube 138 is attached to hinge mechanism 128. Torque tube 138 supports panels 114, 116 in a desired position, such as, for example, in a parabolic position. Referring to FIG. 11, drive train 140 is operably connected to lift arm 142 and motor 144. Drive train 140 generally has driveshaft 146, gears 148, and flexible linking member 150. Lift arm 142 has cam 152 and lifting bar 154. Lifting bar 154 is operably connected to the outside surface 122 of panel 114 or 116. Motor 144 may be any number of motors providing sufficient power to fold and unfold panels 114, 116 between the closed and open positions.
Solar collector 100 also has rotating mechanism 106, as depicted in FIG. 12. Rotating mechanism 106 may be any number of mechanisms that allow solar collector 100 to be rotated. In an example embodiment, rotating mechanism 106 comprises driveshaft 156, spiral gear 158, and a motor (not shown). Spiral gear 158 is operably connected to driveshaft 156 and the motor. The motor may be any number of motors providing sufficient power to rotate trough on support structure 107. Rotating mechanism 106 may also be operably connected to a control circuit or other device adapted to automatically track the sun. Although rotating mechanism 106 is preferably motorized and operably connected to a control circuit or device, rotating mechanism 106 could also be controlled manually by a user.
In operation, solar collector 100 and panels 114, 116 of solar collector 100 can be oriented in any number of positions in any number of ways by actuating folding mechanism 108 or rotating mechanism 106. Generally, folding mechanism 108 individually or simultaneously positions panels 114, 116 between open and closed positions, including into a parabolic position. Referring to FIG. 5-6, panels 114, 116 are oriented in a parabolic position. Referring to FIGS. 7-9, panels are oriented in a closed position. Referring to FIG. 10, panels 114, 116 are oriented in an open position. Generally, rotating mechanism 106 rotates solar collector 100 so that panels 114, 116 simultaneously travel along the same path. For example, rotating mechanism 106 can rotate solar collector 100 with panels 114, 116 in a parabolic position to track the sun. With panels 114, 116 in a closed position, rotating mechanism 106 can rotate solar collector between an upright position, as depicted in FIG. 7, and sideways positions, as depicted in FIGS. 8-9.
Rotating mechanism 106 can rely upon any number of methods or devices known in the art to rotate solar collector 100. In an example embodiment, actuation of a motor (not shown) rotates driveshaft 156. Rotation of driveshaft 156 causes spiral gear 158 to effectuate rotation of torque tube 138. Since panels 114, 116 are rigidly attached to torque tube 138, rotation of torque tube 138 cause panels 114, 116 to rotate along the same path.
One skilled in the art will recognize that rotating mechanism 106 can be operated either manually or automatically without departing from the spirit or scope of the present invention. In an embodiment, rotating mechanism 106 incorporates a control system to time the adjustment of solar collector 100 in relation to movement of the sun. In an embodiment, the control system has a sensor that is responsive to the presence or absence of visible light. The sensor is operably connected to the control system and may be programmable. The control system, in turn, is operably connected to rotating mechanism 106 so that the control system can direct the position of panels 114, 116. For example, the sensor may be active during periods programmed into the control system, such as those times of day when collectable short-wavelength radiation λ can be expected.
In an embodiment, the control system is controlled by a microprocessor and is communicatively connected to a Global Positioning Satellite (GPS) device. The control system receives information from the GPS device. This information may include the position of the sun, the time of day, and/or the time of year. Other sensors may also be included in the control system to obtain and/or relay information regarding weather patterns, local sunrise and sunset, geographical location, environmental conditions, and/or historical use of solar collector 100. In an embodiment, the control system is programmed with an algorithm predictive of the sun's position based upon some or all of this information. Solar collector 100 can thereby be adjusted so as to be oriented toward the sun at different times of day or during different types of environmental conditions.
The control system can be pre-programmed with the desired algorithm, or can be programmed based upon the preferences of a user. In an embodiment, the control system can be controlled remotely, such as by a computer, mobile phone, PDA, or other handheld device. Operation of the remote controller may be by a physical connection (such as a cable or wire) or a wireless connection, such as, for example, by way of an antenna (not shown) communicatively connected to the control system.
Folding mechanism 108 can rely upon any number of methods or devices known in the art to position panels 114, 116. In an example embodiment, actuation of a motor 144 rotates driveshaft 146. Rotation of drive shaft 146 causes rotation of gear 148 a to be rotated. Rotation of gear 148 a drives flexible linking member 150. Flexible linking member 150 may be any number of components, such as, for example, a chain or a belt. As flexible linking member 150 is engaged, gears 148 b, 148 c are rotated. Rotation of gear 148 b actuates cam 152. Actuation of cam 152 axially drives lift arm 154. Since lift arm 154 is attached to panel 116, axial movement of lift arm 154 causes panel 116 to move. Since the rotational direction of driveshaft 146 is reversible by motor 144, lift arm 154 can be operated so as to reversibly open or close panel 116.
Although not shown, folding mechanism 108 can also be adapted to actuate panel 114. For example, gear 148 c could be operably connected to a second cam that axially drives a second lift arm 154 attached to panel 114. The outer edges of panels 114, 116 can thereby be brought together in a manner similar to the closing of a clamshell. Alternatively, motor 144 could actuate a second driveshaft, and a second folding mechanism could be operably connected to panel 114 so that panel 114 can be opened and closed independently of panel 116. Motor 144 of folding mechanism 108 may be the same or different than the motor of rotating mechanism (not shown). In an example embodiment, folding mechanism 108 and rotating mechanism 106 use separate motors.
One skilled in the art will recognize that folding mechanism 108, like rotating mechanism 106, can be operated either manually or automatically without departing from the spirit or scope of the present invention. In an embodiment, rotating mechanism 106 incorporates a programmable control system that allows rotating mechanism to be automatically and manually actuated. In this manner, panels 114, 116 of solar collector 100 can be positioned in a closed, or storage, position when not in use and positioned so as to minimize damage the mirrored inner surface 120 of panels 114, 116 or to the overall structure of solar collector 100.
Referring to FIGS. 5-6, panels 114, 116 of solar collector 100 are positioned in a parabolic position. In the parabolic position, panels 114, 116 and reflective plate 126 substantially form a parabolic trough such that tube 104 runs substantially along focal line 136. Referring to FIG. 15, in the parabolic position, solar collector 100 is able to concentrate short-wavelength radiation λ, such as sunlight, onto tube 104. Specifically, incoming short-wavelength radiation λ₁strikes inside surface 120 of parabolic mirror 102. Due to the parabolic shape of mirror 102, incoming short-wavelength radiation λ₁is redirected to tube 104 as reflected short-wavelength radiation λ₂. Even though short-wavelength radiation λ may approach solar collector 100 from different angles, the parabolic position of panels 114, 116 allows solar collector 100 to concentrate short-wavelength radiation λ onto tube 104.
Referring to FIG. 10, panels 114, 116 of solar collector 100 are positioned in an open position. In the open position, panels 114, 116 lie in a plane that is generally perpendicular to the incidence of short-wavelength radiation λ. Referring to FIG. 18, in the open position, panels 114, 116 can reflect short-wavelength radiation λ. Specifically, incoming short-wavelength radiation λ₁strikes inside surface 120 of parabolic mirror 102. Due to the orientation of panels 114, 116 in the open position, short-wavelength radiation λ is redirected back into space as reflected short-wavelength radiation λ₂. In the open position, up to approximately ninety-eight percent of incoming short-wavelength radiation λ₁can be redirected into space as reflected short-wavelength radiation λ₂.
By redirecting incoming short-wavelength radiation λ₁into space as reflected short-wavelength radiation λ₂, solar collector 100 can prevent reflected short-wavelength radiation λ₂from being absorbed by the local environment and converted to long-wavelength or blackbody radiation. Generally, incoming short-wavelength radiation λ₁that has reached the reflective surfaces of panels 114, 116 comprises wavelengths that have not been absorbed by the atmosphere (such as, for example, by “greenhouse” gases, such as carbon dioxide and methane), and will thus not be absorbed by the atmosphere if immediately redirected through the atmosphere back to outer space as reflected short-wavelength radiation λ₂.
Referring to FIGS. 7-9, panels 114, 116 of solar collector 100 are positioned in a closed position. In the closed position, panels 114, 116 substantially surround tube 104. With panels 114, 116 positioned in the closed position, solar collector 100 can be positioned in an upright position, as depicted in FIG. 7, or in a sideways position, as depicted in FIGS. 8-9. Although not shown, solar collector 100 can be positioned in any number of positions between the upright and sideways positions when panels 114, 116 are in the closed position.
With panels 114, 116 positioned in the closed position, outer surfaces 122 generally aid in the protection of inner surfaces 120, which may be lined with a delicate reflective material or finish such silver foil, coated silver, or polished aluminum. For example, in the absence of direct sunlight, such as at night or under prolonged cloud cover, solar collector 100 may not be able to concentrate sufficient short-wavelength radiation λ onto tube 104 to generate electricity. In such instances, it may be desirable to store solar collector 100 for an extended period of time. During this time, outer surfaces 122 of panels 114, 116 can substantially protect inner surfaces 120 of panels 114, 116 from unwanted deposits such as hail, dust, and animal droppings.
In the upright position with panels 114, 116 closed, the cleaning efficiency of self-cleaning mechanism 110 can also be enhanced. Generally, self-cleaning mechanism 110 delivers cleaning fluid, such as water or a diluted solvent, to nozzle 128. Since the area of the exit opening of nozzle 128 is generally less than the cross-sectional area of the vessel delivering the cleaning fluid to nozzle 128, the pressure of the cleaning fluid will be increased as it exits nozzle 128. This increased pressure helps in removing unwanted deposits on inner surface 120 of mirror 102. In an example embodiment, solar collector 100 can be oriented in the upright position with panels 114, 116 being closed during cleaning. Inner surfaces 120 of panels 114, 116 are thereby brought into closer proximity to nozzles 128. With solar collector 100 in the upright position, gravity is also able to assist the cleaning process. Specifically, residual cleaning fluid can drip down inner surfaces 120 of panels 114, 116, thereby further removing unwanted deposits. In addition, residual cleaning fluid can pass through gap 124 and be recycled through self-cleaning mechanism 110 for repeated application to inner surfaces 120.
In certain instances, it may be desirable to have panels 114, 116 in a closed position but not have solar collector 100 in an upright position, such as during extreme weather. During high winds, for example, particulate matter may travel at sufficiently high velocities to cause significant damage to inner surfaces 120 of mirror 102. Positioning panels 114, 116 of solar collector 100 in an upright position for protective purposes, however, exposes a large surface area upon which wind ω can exert a force, as depicted in FIG. 16. This force, in turn, can damage solar collector by causing collapse or structural fatigue.
In an example embodiment, solar collector 100 can be oriented in a sideways position with panels 114, 116 closed to decrease potential damage due to adverse environment conditions. Specifically, solar collector 100 can be oriented such that panels 114, 116 are substantially parallel with the direct of wind ω, as depicted in FIG. 17. By rotating solar collector 100 from the upright position to a sideways position, the shape of panels 114, 116 can more effectively deflect wind ω. With solar collector 100 oriented in a sideways position parallel to the direction of wind ω, panels 114, 116 can also create a cancelling pressure differential. Specifically, outer surfaces 122 of panels 114, 116 are configured so as to act as air foils. As high winds pass over the outer surfaces 122, resulting areas of low pressure create “negative lift” forces Φ₁, Φ₂that tend to offset each other. By creating opposing forces Φ₁, Φ₂that substantially cancel each other out, the sideways position can thereby stabilize solar collector 100 in high winds.
It will be appreciated by one skilled in the art that panels 114, 116 and solar collector 100 can be positioned into any number of positions other than those shown without departing from the spirit or scope of the present invention. For example, an orientation between the upright and sideways positions may be useful when incident winds c or airborne contaminants and particulates are moving in directions intermediate horizontal or vertical directions. Alternatively, panels 114, 116 can be positioned independently as desired. For example, panel 114 can be positioned in a parabolic position so to redirect incoming short-wavelength radiation λ₁to tube 104 as reflected short-wavelength radiation λ₂, while panel 116 can be oriented into an open position so as to redirect incoming short-wavelength radiation λ₁into space as reflected short-wavelength radiation λ₂, or vice versa. Other reasons for alternative positioning include cleaning, maintenance, and the avoidance of local obstructions, whether temporarily or for an extended period of time.
In an embodiment, solar collector 200 may include heat reservoir system 202, reflector system 204, and fluid delivery system 206. Heat reservoir system 202 includes torque tube 210, torque tube connector 212, and recycling fluid management system 214. Torque tube 210 defines tube channel 216 and axis of rotation R. Torque tube connector 216 may define connector channel 218. Torque tube connector 216 may operably connect two torque tubes 210. In an embodiment, torque tube 210 includes wall 219. Wall 219 generally divides tube channel 216 of torque tube connector 212 from connector channel 218 of torque tube connector 216 such that tube channel 216 and connector channel 218 are not in fluid communication. In another embodiment, interior channel 216 of a first torque tube 210 is in fluid communication with interior channel 216 of a second torque 210 through interior channel 218 of torque tube connector 216. Recycling fluid management system 214 generally includes storage basin 220, fluid-routing matrix 224, spray nozzles 226, drainage trough 228, and pump 229. Recycling fluid management system 214 may include a plurality of pumps 229.
Fluid-routing matrix 224 includes first nozzle conduit 230, second nozzle conduit 232, and nozzle conduit connector 234. In an embodiment, spray nozzles 226 are in fluid communication with second nozzle conduit 232 and storage basin 220 is in fluid communication with first nozzle conduit 230 and nozzle conduit connector 234. In a further embodiment, nozzle conduit connector 230 can be selectively coupled to second nozzle conduit 232 such that storage basin 220, first nozzle conduit 230, nozzle conduit connector 234, second nozzle conduit 232, and spray nozzles 226 are all in fluid communication.
Fluid-routing matrix 224 further includes first torque tube conduit 240, second torque tube conduit 242, torque tube conduit connector 244, and valve 246. In an embodiment, first torque tube conduit 240 is in fluid communication with storage basin 220 and torque tube conduit connector 244. Second torque tube conduit 244 is in fluid communication with valve 246. In a further embodiment, torque tube conduit connector 244 can be selectively coupled to second torque tube conduit connector 242 such that storage basin 220, first torque tube conduit 240, torque tube conduit connector 244, second torque tube conduit 242, and valve 246 are in fluid communication. Valve 246 is generally selectively actuated into and intermediate an open position and a closed position. When valve 246 is open, storage basin 220, first torque tube conduit 240, torque tube conduit connector 244, second torque tube conduit 242, and valve 246 are also in fluid communication with torque tube channel 216.
In an embodiment, fluid-routing matrix 224 may also include a filter (not shown). Filter generally removes debris or other particulate matter from fluid circulating through fluid-routing matrix 224. Filter is generally located between drainage trough 228 and storage basin 220. In this manner, the longevity of components such as spray nozzles 226, pump 229 and valve 246 can be extended.
Reflector system 204 includes panels 250, jack 252, and stepper motor 253. Each panel generally has interior surface 254 and an exterior surface. In an embodiment, interior surface 254 is made from a reflective material. In a further embodiment, exterior surface of panels is coated with a substantially hydrophobic material. Stepper motor 253 is generally operably connector to torque tube 210 such that, when actuated, torque tube 210 can be rotated about axis of rotation R.
Solar collector 200 generally includes two solar panels operably coupled to jack 252. Although panels 250 and jack 252 may be configured in any number of ways, panels 250 and 252 are generally configured as heretofore described with respect to panels 114, 116 and folding mechanism 108. Accordingly, panels 250 can be positioned into any number of position, including a parabolic position, an open position, and a closed position. In the parabolic position, panels 250 generally form a parabola. In the open position, panels are generally oriented in the same direction. In the closed position, a first panel 250 is positioned generally opposite second panel 250 such that the reflective interior surfaces 254 of each of panels 250 substantially confront each other.
In an embodiment, stepper motor 253 is operably connector to heat reservoir system 202, such as, for example, to torque tube 210 or torque tube bellows 212. When actuated, stepper motor provides for rotation of torque tube 210 about axis of rotation R such that panels 250 can be simultaneously positioned. For example, with panels 250 in a closed position, stepper motor 253 can be actuated such that panels can be further positioned into an upright or a sideways position.
Fluid delivery system 206 includes focal conduit 260, spacer conduit 262, coiled conduit 264, control valve 266, and delivery conduit connector 268. In an embodiment, focal conduit 206 is positioned substantially within the focal plane of panels 250 that have been positioned in a parabolic position. Control valve 266 is generally selectively actuated into and intermediate an open position and a closed position. Focal conduit 260 is in fluid communication with spacer conduit. When control valve 246 is open, coiled conduit 264 is in fluid communication with focal conduit and spacer conduit 262. Delivery conduit connector 268 operably connects a first fluid delivery system 206 to a second fluid delivery system 206.
In operation, solar collector 100 may be employed as part of a system or method to help maintain an approximate balance between solar radiation received by the earth and solar radiation redirected to space. An imbalance will cause the total amount of radiation retained to either increase or decrease. When an imbalance results from excessive conversion of incident shortwave radiation to long-wavelength radiation, the localized temperature, and ultimately the temperature of the earth, will increase progressively. Because short-wavelength radiation λ from the sun is converted to long-wavelength blackbody radiation after absorption by the earth, solar collector 100 can be used to stop some amount of short-wavelength radiation λ from being converted and thus play a role in reducing undesirable localized heating.
When configured to assume an open position for redirecting short-wavelength radiation λ to space, solar collector can thereby be used as part of a system or method for reducing local temperatures, and thus the need for cooling equipment, with a concomitant reduction in consumption of energy. Moreover, redirection of short-wavelength radiation λ by way of solar collector 100 does not add carbon dioxide, methane, or other contaminants into the earth's atmosphere.
FIG. 15A is a cross-sectional illustration of a parabolic trough formed by a solar collector according to an embodiment of the present invention water vapor to the atmosphere, all of which are known to block transmission of long wavelength radiation back to space. Therefore, solar collector 100 can be used as part of a system or method to reduce imbalances between absorption and redirection of solar energy on both a local and global scale.
In further embodiments, solar collector 200 can be used to store and recover heat and is especially well-adapted for the optimization of water handling. Although the following describes the use of embodiments of solar collectors 200 adapted to store and recover heat through the use of water as a heat exchanger, alternative embodiments of solar collectors may be adapted utilize the steam. In general, such embodiments can be used to provide a thermal source that can be routed for the production of electricity.
Referring to FIGS. 19-22, an embodiment of solar collector 200 can utilize stored fluid, such as, for example, water, for a plurality of purposes. Moreover, solar collector recycles the fluid so that repeated use of the same fluid can be achieved. Solar collector 200 can also collect water from the surrounding environment from to use for these various purposes. As a result, solar collector can be a self-contained system with respect to water use. Solar collector 200 can thereby be used in substantially arid climates, such as, for example, in the desert, without the need to integrate an external system for purposes of supplying fluid. Once skilled in the art will recognize, however, that such an external system for supplying fluid may nonetheless be integrated into solar collector 200.
A feature and advantage of the present invention is an ability to control water connections between components in relative motion. As torque tube 210 is rotated as a result of actuation by stepper motor 229, second nozzle conduit 232 is displaced relative to first nozzle conduit 230 and first torque tube conduit 240 is displaced from second torque tube conduit 242. Nozzle conduit connector 234 generally permits second nozzle conduit 232 to be selectively positionable into fluid communication with first nozzle conduit 230. Similarly, torque tube conduit connector 244 generally permits second torque tube conduit 242 to be selectively positionable into fluid communication with first torque tube connector 240.
In an embodiment, nozzle conduit connector 234 and torque tube conduit connectors 244 comprise inflatable bellows and a corresponding tip. The corresponding tip may, for example, be a pin extension adapted to mate with the inflatable bellows through a valve closure. Access to spray nozzles 226 is through second nozzle conduit 232, which rotates with nozzle conduit connector 234 when torque tube 210 is rotated. Stepper motor 259 can be actuated such that first and second nozzle conduits 230, 232 are substantially aligned and so that the first and second torque tube conduits 240, 242 are substantially aligned.
In an embodiment, pump 229 can be actuated such that fluid from storage basin 220 fills bellows of nozzle conduit connector 234. If pump 229 is actuated when first and second nozzle conduits 230, 232 are substantially aligned, the bellows expand such that the tip, which is coupled to second conduit connector 232, penetrates the valve closure of the bellows, thereby bring first and second nozzle conduits 230, 232 into fluid communication. Fluid can thereby flow from storage basin 220, through first and second nozzle conduits 230, 232 and nozzle conduit connector 234, and into spray nozzles 226. One skilled in the art will readily recognize that the opening spray nozzles 226 can be adapted to produce any number of spray patterns Although jack 252 can be actuated to circulate fluid through fluid-routing matrix 224 with panels 250 oriented in any number of positions, jack 252 is generally actuated such that panels 250 occupy a substantially closed position.
At the discretion of a user or based upon computer system programmed with a selected algorithm, actuation of pump 229 can be terminated. With pump 229 turned on, fluid pressure within the bellows of nozzle conduit connector 234 decreases. As a result of the decrease in fluid pressure, the bellows can retract from the connector tip. Retraction of the bellows thereby provides sufficient clearance such that torque tube 210 can be rotated without interference between first and second nozzle conduits 230, 232.
Another feature and advantage of the present invention is the ability to operably connect a plurality of solar connectors 200 while maintaining the ability to independently rotate torque tube 210 of each solar collector 200 without affecting the integrity of each fluid delivery system 206. In particular, as torque tube 210 is rotated about axis or rotation R, the components of fluid delivery system 206 are correspondingly rotated. Respective fluid delivery systems 206 are operably coupled at delivery conduit connector 268. Delivery conduit connector 268 generally provides for relative rotational movement of respective coiled conduits 264. In an embodiment, delivery conduit connector 268 is a bellows.
A further feature and advantage of the present invention is the ability to store the heat generated through the collection of solar radiation. As a result, solar collector 200 can deliver thermal energy for the production of electricity during periods of time when solar radiation may be impaired or absent, such as, for example, during cloudy days or at night. In an embodiment, when valve 246 is closed, tube channel 216 of torque tube 210 is a substantially sealed environment such that fluid cannot escape from tube 216.
In an embodiment, valve 246 can be opened and pump 229 can be actuated such that tube channel 216 is filled with fluid. With tube channel 216 filled, valve 246 can be closed and pump 229 can be shut off. Referring to FIGS. 19-22, coiled conduit 264 is located within, but not in fluid communication with, tube channel 216. Fluid in focal conduit 260 can be heated due to the reflection of solar radiation by panels 250. As previously and described with respect to tube 104 of solar collector 100, the heated fluid can be circulated through fluid delivery system 206. Since the temperature of the heated fluid within fluid delivery system 206 generally exceeds the temperature of the fluid within tube channel 216 of torque tube 210, heat can be transferred from the fluid within fluid delivery system 206 to the fluid within torque tube 210. In this manner, heat can be extracted from the heated fluid circulating through fluid delivery system 206.
Solar collector can be adapted such that the heated fluid within torque tube 210 substantially retains heat. In particular, control valve 266 can be closed such that coiled conduit 264 is substantially evacuated of fluid, thereby reducing heat transfer out of tube channel 216. Torque tube 210 may also be coated with, or otherwise encapsulated by, an insulative material. In addition, the interior surface of torque 210 can be smoothed so as to reduce conductive surface area.
Heat stored by the fluid within tube channel 210 can then be recovered by re-opening control valve 266 and activating fluid delivery system 206. Fluid thereby begins circulating through coiled conduit 264. Due to potential temperature differences, heat can thereby be transferred from the fluid within torque tube 210 to the fluid within torque tube 210.
In an embodiment, the fluid introduced into torque tube 210 and surrounding coiled conduit 264 is generally at or around atmospheric pressure, or 1 ATM at sea level. When valve 246 is sealed, the fluid can be heated to temperatures proportions to the temperature of the fluid within coiled conduit 264 of fluid delivery system 206. If the working temperature of the fluid within torque tube exceeds normal atmospheric boiling point (e.g., 100° C. for water), steam will form within torque tube 210. As a result of the formation of steam, the pressure within tube channel 216 of torque tube 210 increases, thereby increasing the boiling point of the fluid therein. For example, a working temperature of 285° C. for the fluid within coiled conduit 264 may increase the pressure of the fluid confined within the torque tube 210 by almost 50 bar, or 100 psi.
With the temperature of the fluid within torque tube 210 sufficiently elevated, valve 246 can be opened such that the fluid flashes to steam upon experiencing a sudden reduction in boiling point. Such flashing generally occurs provided that valve 246 remains open and until the internal pressure of torque tube 210 falls below atmospheric pressure. In an embodiment, the availability of steam can be further utilized to generate electricity. If desired or required for operation of equipment for processing equipment, the availability of steam can be extended through the periodic addition of fluid and the application of heat generated by electric or fossil fuel sources. Such fluid could be supplied, for example, from storage basin 220 through an arrangement of conduit fittings similar to the arrangement of spray nozzles 226.
It should be noted that the release of water from pressurized confinement may explosively actuated. In particular, the ejected water-turned-to-steam may momentarily cause an ambient surge of water droplets at the outlet of valve 246, thereby creating a vapor cloud having pressure initially about equal to that of the superheated fluid (1,000 psi), and then declining to atmospheric pressure wherein a vapor cloud would form in ambient surroundings. Both of these modes—pressure surge and vapor cloud—have utility in connection with solar collector installations.
In an embodiment, the pressure surge can achieve neutralization of significant pressure depressions, as may be due to severe weather conditions, such as, for example, thunderstorms, tornadoes, and hurricanes. On the other hand, a pressure surge of water droplets can control large positive pressure spikes such as might occur due to fuel deflagrations. Vapor clouds may naturally follow an initial pressure surge, and can capture and/or neutralize particulate matter with which the clouds come in contact.
To facilitate this capability, in an embodiment, solar collector 200 may be fitted with pressure release nozzles along the length of each torque tube 200 carrying water under pressure, and may incorporate pressure sensors capable of response to either negative or positive pressure deviations. Such solar collectors 200 may also include the ability to measure temperature, wind velocity, and optical density of ambient air. Such capabilities could be use to detect and facilitate responses to wild fires and/or deflagrations occurring close to collector installations, severe dust or particulate storms that could damage solar collector 200, and pressure depressions typical of severe atmospheric conditions. An active response agent in each of these cases may include pressurized water droplets.
Yet another feature and advantage of the present invention is water utilization. In an embodiment, solar collector 200 can be adapted for use without an external water source or to provide a source of potable water. When oriented in an open or parabolic position, panels 250 can capture rainfall. In particular, water droplets can contact the reflective surface 254 of panel 250. The parabolic shape and relatively smooth reflective surface of panels 250 facilitates the effect of gravity in urging the droplets to toward the bottom solar collector 200. Drainage trough 228 can then route the collection of water droplet to storage basin 220 for storage. In an embodiment, the outer surface of panels 250 can be coated with a hydrophilic material to facilitate the condensation of water vapor from the air on the surface of panels 250. As this condensation accumulates, water droplets may form of sufficient size such that they can be collected within storage basin.
A device, method, or system incorporating features described herein may be used for collecting solar energy and for rejecting short-wavelength radiation λ back to space by positioning panels 114, 116 in various configurations. For example, one or more solar collectors 100 could be installed on large buildings to gather heat during cold weather, but also made capable of rejecting short-wavelength radiation λ to reduce the consumption of energy by air conditioners during warm weather.
Deployment of solar collector 100, whether in single units, units spaced in close proximity to each other, or units spaced apart, may also be part of a large-scale system or method to offset the effects of climate change. If large amounts of short-wavelength radiation λ from the sun are sent back into space before heating the structures or the earth proximate solar collector 100, localized buildup of heat from solar insolation can be reduced, thus effectively cooling buildings or other localized zones proximal solar collector 100 and also tending to reduce the ability of increasing “greenhouse” gases in the atmosphere to contribute to climate change.

Claims

1. A solar collector for concentrating solar radiation, the solar collector comprising:

a substantially parabolic reflector defining a focus line spaced apart from the reflector, the substantially parabolic reflector presenting a first mirrored surface for reflecting the solar radiation to the focus line;

a pivot housing operably coupled to the substantially parabolic reflector, the pivot housing defining a substantially enclosed sealable interior channel and an axis of rotation, the pivot housing further being positioned substantially proximal the vertex of the substantially parabolic reflector, the solar collector being shiftable about the axis of rotation;

a first conduit positioned substantially along the focus line of the substantially parabolic reflector;

a second conduit positioned within the pivot housing;

a conduit valve operably coupling the first fluid conduit and the second fluid conduit such that the first fluid conduit and the second fluid conduit are in interruptable fluid communication;

a reservoir system adapted to contain a fluid that can be sealed within the interior channel of the pivot housing; and

a reservoir valve operably coupling the interior channel of the pivot housing and the reservoir system such that the interior channel and the reservoir system are in interruptable fluid communication.

2. The solar collector of claim 1, wherein the substantially parabolic reflector includes articulated first and second reflective panels operably shiftably coupled to the pivot housing.

3. The solar collector of claim 2, wherein the first and second reflective panels are shiftable between a folded position and an open position, the first and second reflective panels forming a substantially parabolic shape intermediate the folded position and the open position.

4. The solar collector of claim 1, wherein the reservoir system comprises a storage section, a delivery section, and an actuatable coupling valve for selectively coupling the storage section to the delivery section, the storage section being in fluid communication with the delivery section when the actuatable coupling valve is actuated and the pivot housing is freely rotatable when the actuable coupling valve is not actuated.

5. The solar collector of claim 1, further comprising a pump for creating an increase in fluid pressure in the storage section of the reservoir system, the increase in fluid pressure causing the actuatable coupling valve to couple the storage section with the delivery section.

6. The solar collector of claim 1, wherein the interior channel of the pivot housing defines a substantially sealed environment when the reservoir valve is closed.

7. The solar collector of claim 1, wherein the second conduit includes a coiled region.

8. A solar collector for concentrating solar radiation, the solar collector comprising:

a cleaning system for applying a fluid to the first mirrored surface;

a reservoir system adapted to communicate the fluid to the cleaning system; and

a drainage system for communicating fluid collected by the first reflective panel to the reservoir system.

9. The solar collector of claim 8, wherein the substantially parabolic reflector includes articulated first and second reflective panels operably shiftably coupled to the pivot housing.

10. The solar collector of claim 9, wherein the first and second reflective panels are shiftable between a folded position and an open position, the first and second reflective panels forming a substantially parabolic shape intermediate the folded position and the open position.

11. The solar collector of claim 8, wherein the reservoir system comprises a storage section, a delivery section, and an actuatable coupling valve for selectively coupling the storage section to the delivery section, the storage section being in fluid communication with the delivery section when the actuatable coupling valve is actuated and the pivot housing is freely rotatable when the actuable coupling valve is not actuated.

12. The solar collector of claim 10, further comprising a plurality of nozzles adapted to spray the fluid onto the first mirrored surface of the reflector when the first and second reflective panels are shifted into a closed positioned.

13. The solar collector of claim 8, wherein the first mirrored surface of the substantially parabolic reflector, the cleaning system, the reservoir system, and the drainage system define a substantially closed system such that the fluid can be applied to the first mirrored surface and circulated through the cleaning, reservoir, and drainage systems in multiple cycles.

14. The solar collector of claim 9, wherein the substantially parabolic reflector defines a second surface, the second surface being coated with a substantially hydrophilic material for facilitating condensation of moisture on the second surface.

15. The solar collector of claim 14, wherein the first and second reflective panels are shiftable such that the moisture is gravitationally communicated to the drainage system.

16. The solar collector of claim 8, further comprising a pump for creating an increase in fluid pressure in the storage section of the reservoir system, the increase in fluid pressure causing the actuatable coupling valve to couple the storage section with the delivery section.

17. A method of collecting solar radiation from a solar collector, the solar collector including a substantially parabolic reflector defining a focus line spaced apart from the reflector and having a first mirrored surface adapted to reflect the solar radiation to the focus line, a pivot housing defining an interior channel, and a reservoir system adapted to communicate fluid to the interior channel of the pivot housing, the method comprising:

communicating a first fluid from the reservoir system to the interior channel of the pivot housing;

substantially sealing the fluid within the interior channel of the pivot system;

reflecting solar radiation with a first reflective panel toward the focus line;

receiving the solar radiation with a first conduit positioned at the focus line;

communicating a second fluid from the first conduit to a second conduit positioned within the interior channel of the pivot housing; and

transferring heat from the second fluid to the first fluid.

18. The method of claim 17, further comprising:

evacuating the second fluid from the second conduit;

re-communicating the second fluid into the second conduit;

transferring heat from the first fluid to the second fluid; and

converting the heat into electricity in the absence of reflection of the solar radiation by the substantially parabolic reflector.

19. The method of claim 17, further comprising evacuating the interior channel of the pivot housing of the first fluid.

20. A method of cleaning a solar collector, the solar collector including a substantially parabolic reflector defining a focus line spaced apart from the reflector and having a first mirrored surface adapted to reflect the solar radiation to the focus line, a pivot housing defining an interior channel, a drainage system, a reservoir system, and a cleaning system, the method comprising:

communicating a fluid from the first mirrored surface of the substantially parabolic reflector to the fluid drainage system;

communicating the fluid from the drainage system to the reservoir system;

communicating the fluid from the reservoir system to the cleaning system; and

applying the fluid to the reflective surface of the first mirrored surface of the substantially parabolic reflector.

21. The method of claim 20, wherein communicating the fluid from the first mirrored surface of the substantially parabolic reflector to the fluid drainage system comprises collecting the fluid in a drainage trough.

22. The method of claim 20, wherein the fluid is rainwater.

23. The method of claim 20, wherein the substantially parabolic reflector comprises a second surface coated with a substantially hydrophilic material for facilitating condensation of moisture on the second surface, the method further comprising:

facilitating the condensation of water on the second surface of substantially parabolic reflector; and

communicating the water from the second surface of the substantially parabolic panel to the drainage system.

24. A solar collector for concentrating solar radiation, the solar collector comprising:

a second conduit positioned within the pivot tube;

a reservoir system adapted to contain a fluid that can be sealed within the interior channel of the pivot housing;

a cleaning system for applying a second fluid to the first mirrored surface of the substantially parabolic reflector;

a reservoir system adapted to communicate the second fluid to the cleaning system;

a drainage system for communicating fluid collected by the substantially parabolic reflector to the reservoir system; and

25. The solar collector of claim 24, wherein the substantially parabolic reflector includes articulated first and second reflective panels operably shiftably coupled to the pivot housing.

26. The solar collector of claim 24, wherein the first and second reflective panels are shiftable between a folded position and an open position, the first and second reflective panels forming a substantially parabolic shape intermediate the folded position and the open position.

27. The method of claim 17, further comprising:

converting a portion of the fluid within the interior channel of the pivot housing into steam;

pressurizing the first fluid within the interior channel of the pivot housing.

28. The method of claim 27, wherein pressurizing the first fluid comprises increasing a pressure within the interior channel of the pivot housing to approximately 1,000 psi.

29. The method of claim 27, further comprising releasing the first fluid from the interior channel through explosive actuation.

30. The method of claim 29, further comprising neutralizing pressure depressions caused by severe weather conditions.

31. The method of claim 29, further comprising stabilizing pressure increases due to fuel deflagrations.