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Publication numberUS20080184989 A1
Publication typeApplication
Application numberUS 11/273,166
Publication dateAug 7, 2008
Filing dateNov 14, 2005
Priority dateNov 14, 2005
Also published asEP1949007A2, EP1949007A4, WO2007058834A2, WO2007058834A3
Publication number11273166, 273166, US 2008/0184989 A1, US 2008/184989 A1, US 20080184989 A1, US 20080184989A1, US 2008184989 A1, US 2008184989A1, US-A1-20080184989, US-A1-2008184989, US2008/0184989A1, US2008/184989A1, US20080184989 A1, US20080184989A1, US2008184989 A1, US2008184989A1
InventorsTravis W. Mecham
Original AssigneeMecham Travis W
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Solar blackbody waveguide for high pressure and high temperature applications
US 20080184989 A1
Abstract
A solar blackbody waveguide that captures and uses sunlight to heat a thermal heat transfer fluid. One or more systems of optical mirrors provided on each tower captures and concentrates the sunlight. Each system of optical mirrors is movably mounted on its tower to track the daily movement of the sun and to maintain the proper angle with the horizon throughout the year. Each system of optical mirrors directs the light into an associated short light pipe which delivers the light into a curved solar coil contained within an enclosure. Energy from the light rays is absorbed by the solar coil and transferred to thermal working fluid or heat transfer fluid flowing between the solar coil and the enclosure. The energy laden thermal heat transfer fluid is gathered from a plurality of towers for use with existing technologies, such as with a combined cycle gas turbine, boiler, or steam generator.
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Claims(12)
1. A solar blackbody waveguide for high pressure and high temperature applications comprising:
a means for collecting and concentrating ambient solar flux,
a hollow lossy solar coil surrounded by an insulated enclosure,
a means for directing the concentrated flux from the means for collecting and concentrating ambient solar flux into an interior of the hollow lossy solar coil in a manner that the concentrated solar flux makes repeated reflections off interior surfaces on the solar coil causing the energy from the concentrated solar flux to be absorbed as heat energy into the solar coil, the solar coil being formed into a varying alignment configuration and located within the insulated enclosure,
said insulated enclosure spaced apart from walls of the enclosure so that an enclosed space is formed between the solar coil and walls of the enclosure; and
a thermal fluid moving within the enclosed space of the enclosure in a manner that the thermal fluid receives heat energy from the solar coil which can be used as a source of energy inside the enclosure or can be used as a source of energy outside the enclosure upon removal of heated thermal fluid from the enclosure.
2. A solar blackbody waveguide for high pressure and high temperature applications according to claim 1 further comprising:
a dual-axis tracking means attached to the means for collecting and concentrating ambient solar flux in order to maintain the means for collection and concentrating ambient solar flux in proper angular alignment with the sun by constantly and automatically tracking the apparent movement of the azimuth angle and altitude angle of the sun with respect to the location of the solar blackbody on earth as the earth rotates daily and progresses through its annual orbit about the sun.
3. A solar blackbody waveguide for high pressure and high temperature applications according to claim 1 wherein the means for collecting and concentrating solar flux further comprises:
a system of optical mirrors.
4. A solar blackbody waveguide for high pressure and high temperature applications according to claim 1 wherein the means for collecting and concentrating solar flux further comprises:
a system of optical lenses.
5. A solar blackbody waveguide for high pressure and high temperature applications according to claim 1 wherein the means for directing the concentrated flux into the interior of a hollow, lossy solar coil further comprises:
a lossless optical waveguide.
6. A solar blackbody waveguide for high pressure and high temperature applications according to claim 5 wherein the lossless optical waveguide may be mirrored, reflective surfaces or light pipes utilizing the physical property of total internal reflection, including optical tees, optical reducers, or solar horns.
7. A solar blackbody waveguide for high pressure and high temperature applications according to claim 1 wherein the hollow, lossy solar coil further comprises:
a hollow lossy waveguide for electromagnetic radiation;
said hollow lossy waveguide being constructed of metallic or other electrically and thermally conductive materials so that concentrated solar flux introduced into the lossy waveguide at a series of acute angles to the longitudinal axis of the waveguide will tend to propagate along the longitudinal axis making numerous reflections on interior walls of the waveguide with a loss of energy upon each successive reflection and causing energy contained in the solar flux to be converted into heat energy which is conducted through the solar coil to exterior walls of the lossy waveguide.
8. A solar blackbody waveguide for high pressure and high temperature applications according to claim 1 further comprising:
said solar coil provided externally with appurtenances to enhance thermodynamic heat transfer processes between the coil and the thermal fluid.
9. A solar blackbody waveguide for high pressure and high temperature applications according to claim 1 wherein said insulated enclosure is provided with a suitable insulation system to mitigate loss of heat from the enclosure to the environment.
10. A solar blackbody waveguide for high pressure and high temperature applications according to claim 1 wherein said means for collecting and concentrating ambient solar flux and said hollow lossy solar coil and associated enclosure are co-located with other facilities in areas suitable for dual land use in order to reducing the overall environmental impact on Visual Resources by minimizing development of new, large land areas for energy production using solar technologies.
11. A method for converting solar flux to heat energy employing a one or more solar blackbody waveguides for high pressure and temperature applications comprising:
capturing and concentrating light rays from the sun using a system of optical mirrors or a system of optical lenses,
guiding the concentrated light rays through a lossless waveguide into the interior of a hollow continuous solar coil contained within an insulated enclosure,
converting the concentrated light rays into heat energy by multiple reflections of the concentrated light rays against the walls of the solar coil,
transferring the heat energy from the walls of the solar coil into a thermal fluid contained in a space provided between the enclosure and the solar coil, and
using the heat energy contained within the thermal fluid for any process requiring heat.
12. A method for converting solar flux to heat energy employing a one or more solar blackbody waveguides for high pressure and temperature applications according to claim 11 further comprising the following step that is performed continuously:
moving the system of optical mirrors or optical lenses so that optical mirrors of the system of optical mirrors are constantly facing the sun and track the sun through its daily and seasonal apparent movement across the sky.
Description
BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a solar blackbody waveguide that captures and uses sunlight to heat a thermal working fluid, such as air or water. A system of optical mirrors associated with each solar blackbody waveguide collects and concentrates the sunlight and the sunlight is then directed to the solar blackbody waveguide. The system of mirrors is preferably mounted on a tower so that the system of mirrors can be moved on a dual axis to track the daily movement of the sun and can be tilted to maintain the proper orientation as the angle of the sun with the horizon changes throughout the day and the year. The light rays are directed form the system of mirrors into the solar coil component of its associated solar blackbody waveguide. Energy from the light rays is absorbed by the solar coil and transferred into a thermal working fluid in the space provided between the solar coil and an enclosure vessel in which the solar coil component of the solar blackbody waveguide is located. A plurality of these solar blackbody waveguide units can be connected together so that they cooperate to produce a large volume of energy laden thermal working fluid. The resulting energy laden thermal working fluid can then be used with existing technologies, such as any type of commercial or industrial application requiring hot water, steam or heat. For example, the present invention can be used as an air preheater to heat air for use in association with a combined cycle gas turbine. If water is used as the thermal working fluid, the present invention could be used as a steam generator for use in steam cycle turbine plants or other commercial or industrial processes requiring steam.

2. Description of the Related Art

The effective use of solar flux as a source of heat to drive heat engines has been the aim of numerous thermal-solar energy technologies. Unlike photoelectric solar cells which convert solar energy directly into electrical energy, thermal-solar technologies convert solar energy into heat which is then converted into mechanical energy and finally into electrical energy. Typically, at the center of this conversion process in current technologies is the steam or Rankine cycle.

Low cost production of electricity using current steam cycle technologies is based on magnitude-of-scale production. Production of electricity in the Megawatt (MW) range requires enormous amounts of heat. Assembling enough energy from weak solar energy in a single location to power a generator in this range remains the defining technical challenge of this form of solar energy.

The low energy-density of ambient sunlight requires that the geometry of concentrator assemblies be very large. Assembling enough energy in one location to power a large heat engine has been handled by three primary methods. The first method uses thermal transfer fluid to accumulate heat as it passes from one incremental heat generator to another. The second method transmits large quantities of solar energy over large distances in a nearly lossless manner to a single “receiver” point. The third method generates electricity using small generator systems and the total produced power is then assembled via a distributed electrical bus.

Systems involving each of all of these three methodologies have been developed to the point of operation. However, each system has introduced its own technical complications, thermal losses, and inefficiencies as described briefly below.

Several trough systems were built in the mid to late 1980's. One such system was the parabolic trough system. This type of system incrementally accumulates energy by using a heat transfer fluid. Sunlight is focused using a parabolic trough-shaped mirror on to a pipe containing a heat transfer fluid, typically thermal oil. This hot oil is passed successively through a number of parabolic trough concentrators until the temperature of the oil is heated to approximately 390° C. (735° F.). This hot oil is then passed through a heat exchanger to generate superheated steam from which electricity is generated using a conventional steam turbine.

The parabolic trough system has several drawbacks. This system has high thermal losses due to the fact that the oil-filled pipe at the center of the. concentrator trough is not insulated and re-radiates the accumulated heat back into space. Also, not all the solar energy incident on the pipe containing the heat transfer fluid is absorbed by the fluid. In fact, most of the energy is reflected. In addition, use of a heat exchanger in the steam generator loop increases the overall inefficiencies of the system. These components combine to limit the gains that can be acquired from magnitude-of-scale operation. In addition, there are other limitations for these implementations since these systems do not track the sun from east to west, although they do track the seasonal inclination angle. As a result, they are typically constructed with a “due-south” orientation and are most effective in the late morning to early afternoon.

At least two power tower systems were built in the mid 1980's to mid 1990's. This type of system concentrates sunlight over a large area by transmitting it in a lossless manner through ambient air to a receiver point located at the top of a power tower. Mirrors or heliostats are mounted on the ground surrounding the power tower. These heliostats track the sun and reflect the light from the sun up to the power tower where a thermal fluid system is located. The power tower is in essence a large, fragmented collector dish distributed over a large area. The heat transfer fluid is molten sodium which is heated to approximately to 570° C. (1050° F.) as it passes through the receiver at the focal point of the power tower. This thermal fluid is then passed through a heat exchanger to generate superheated steam from which electricity is generated using a conventional steam turbine.

The power tower system also has several drawbacks. This system has high thermal losses. With the receiver suspended in the air with limited insulation, it re-radiates accumulated heat back into space. Additionally, use of a heat exchanger in the steam generator loop increases the overall inefficiencies of the system. These thermal considerations combine to limit the gains that can be acquired from magnitude-of-scale construction and lower the overall thermal efficiency. In addition, there are other limitations for power towers since self-shadowing of the heliostats keeps them from providing power over the entire day.

Dish engine systems are in the advanced prototype phase with test facilities deployed in the late 1990's. These systems use an array of parabolic dish-shaped mirrors to focus solar flux to a small “receiver” located at the focal point of the parabolic mirror assembly. A thermal working fluid of air or hydrogen is heated to about 750° C. (1380° F.) and used directly to generate electricity using a small turbine or Stirling Engine attached to the dish without use of a heat exchanger. The electricity generated is collected using a system of electrical buses or collection systems for final connection to the utility electric grid. Due to the higher operating temperatures and elimination of heat exchangers, these systems have higher thermal efficiencies than parabolic troughs and power towers.

However, these dish engine systems do not overcome the same basic drawback of the other technologies, i.e. high thermal losses with the receiver suspended in the air with limited insulation and resultant re-radiation of accumulated heat back into space. These systems can track the daily progress of the sun, and therefore, provide power for longer periods during the day. The addition of turbines or Stirling Engines attached to the dish generator increases the structural load-bearing requirements of the support system. The structures required to support the dish and engine can become massive and expensive to construct.

The current art in solar-thermal energy recognizes the need to effectively accumulate the necessary amounts of heat for magnitude-of-scale production. However, the means for doing this as demonstrated in the art is not entirely physically realizable. An example is shown in U.S. Pat. No. 4,982,723 where solar energy is introduced into a thermal fluid inducing a photochemical reaction. In this process, the need for accumulation of energy is recognized, but the physical mechanism for making it happen on a large scale is sketchy.

Another technology is reflected in U.S. Pat. No. 4,841,946 in which a Cassegrain reflector is used to concentrate solar flux. This concentrated flux is transported via light pipe to a cavity where the solar energy is converted into heat energy. Although this patent contains some interesting abstract concepts, it does not obtain a complete solution when scaled up for actual power production levels. This proposed technology implies (without a realizable solution) that if more energy is required, the energy from a plurality of similarly situated reflectors can be conducted to a single receiver via a plurality of light pipes. An inherent difficultly that this technology fails to overcome is the transmission losses associated with moving highly concentrated solar energy via light pipes over long distances. Although these losses are small, they are not zero, and a transmission loss of one tenth of one percent (0.1%) in a light pipe carrying one (1) MW of energy is an enormous amount of energy to be absorbed by the material from which the light pipe is constructed. Nor does this technology propose any useful method for combining light from the plurality of light pipes into a single, common light pipe for long distance transmission.

Applicant's own previous invention which is described in U.S. Pat. No. 6,899,097 which was filed on May 26, 2004 and issued on May 31, 2005 for Solar Blackbody Waveguide for Efficient and Effective Conversion of Solar Flux to Heat Energy addresses many of these problems. However, one drawback of that previous invention is that the solar coil waveguide employed in that solar blackbody and into which a plurality of towers of solar arrays fed was linear. Because the solar coil was straight, the solar blackbody waveguide had to extend a long distance in order to capture sufficient heat energy to be commercially useful. Thus, the land requirements for this type of installation made the installation expensive and required the mechanical separation of large equipment components such as compressors and turbines. Also, relief of linear thermal stress presented some of the most difficult large scale engineering challenges.

Another problem with Applicant's prior invention is that light collected from multiple towers was fed into a single solar blackbody waveguide, which required an elaborate and expensive system of solar light pipes, solar horns, etc. Also, because the solar flux was transmitted via the tower down to the ground, the light rays had to traverse the structural support and tracking mechanism by which the tower was positioned and tilted to follow the sun. This added to the complexity and expense of Applicant's previous invention and introduced potential energy losses via the light pipes.

Still another shortcoming of Applicant's previous invention is that the solar blackbody waveguide used in that invention was buried underground. This made initial installation of the equipment more complicated and expensive. And because the equipment was relatively inaccessible, this also made repair of the equipment more difficult and expensive. Additionally, because a large proportion of the equipment for Applicant's previous invention was located underground, this type of installation was not suitable for certain types of terrain, such as extremely rocky or swampy areas. Also, this type of installation was particularly susceptible to damage in the event of movement of the earth, such as in the event of earth tremors or earthquakes.

It has long been recognized that efficiency of a turbine based-heat engine is related to the combustion temperature and the compression ratio. Restated, this indicates the higher the temperature at the inlet to the turbine, the higher the efficiency and, simultaneously, the higher the pressure at the inlet to the turbine, the higher the efficiency. Applicant's previous invention was limited in its pressure and temperature capabilities, intrinsically limiting its overall efficiency potential.

One of the primary drawbacks to large-scale solar and wind farm generating facilities is the environmental impact resulting from the large land-usage on which these projects are sited. Every large power-generation plant to be constructed in the future in the United States will be subjected to state Environmental Impact Statement (EIS) processes or federal Environmental Impact Report (EIR) requirements. Often energy projects are subjected to both federal and state environmental studies during the permitting phases of the project. Assessment of project impact on Visual Resources is an important factor in regulatory considerations for approval of these projects. Applicant's previous invention contemplated land-use for solar technologies only.

The present invention addresses these shortcomings by employing a solar coil that is curved into a circular, helical, or spiral shape instead of being linear. Use of a curved solar coil provides for simple thermal stress relief and allows the present invention to be installed in much smaller areas and allows this system to be combined in the same area with other energy gathering technologies, such as, for example, within an existing wind power collection field. By employing the same land for both solar and wind power collection, the cost of land for installation is greatly reduced and the productivity per unit of collection area is increased. This dual land usage also decreases the overall environmental impact on Visual Resources, since the same land can be used to co-locate solar technologies, wind technologies, or other energy production facilities. Also, because of the smaller space requirements of this present invention over Applicant's prior invention, this present type of invention can be added as a retrofit into existing wind power collection fields.

The present invention also eliminates the need for multiple towers to feed into a single solar blackbody waveguide. By providing a separate solar blackbody waveguide in association with each system of optical concentrating mirrors and designing the system so that light rays do not have to traverse the mechanism for rotating and tilting the tower, the need for light pipe is minimized or eliminated altogether and the equipment needed to direct light from the collection and concentration mirrors into the solar coils in the present invention is greatly simplified over those required in Applicant's earlier invention. This results in a large reduction in installation and maintenance costs and an increase in the overall solar-to-heat conversion efficiency.

The improvements in the present invention also provide for higher operating pressures and temperatures of the thermal fluid, thus permitting increases in the thermodynamic efficiency of turbine-based heat engine technologies. Since the heat is accumulated in the thermal fluid, which is transported through a series of blackbody waveguides, the present invention can be hybridized using a variety of auxiliary fuels, including coal, nuclear, natural gas, and other renewable fuel sources such as biomass and trash. This is an improvement over the Applicant's previous invention which contemplated hybridization primarily with natural gas.

Finally, the most complex components of the present invention, i.e. those with the greatest need for maintenance, are installed above ground. By eliminating the need for the solar blackbody waveguide to be buried in the ground, the equipment is less complicated and more accessible. This reduces installation and maintenance costs and associated difficulties during operation. Also, with all of the critical equipment located above ground in the present invention, this type of installation is suitable for a wide range of terrains and is not as susceptible to damage in the event of earthquakes.

SUMMARY OF THE INVENTION

The present invention is a solar blackbody waveguide that is particularly suitable for high pressure, high temperature applications. The solar blackbody waveguide captures and uses sunlight to heat a thermal working fluid, such as air or water. Once the thermal working fluid is heated, it can then be used in association with existing technologies. For example, the present invention can be used as an air preheater to heat air for use in association with a combined cycle gas turbine or in other industrial or commercial applications where heat, steam or hot water is needed.

The present invention employs a system of optical mirrors movably mounted on a tower so that the mirrors can be moved to track the daily movement of the sun across the sky due to the rotation of the earth and can be tilted to maintain the proper orientation as the angle of the sun with the horizon changes due to the annual orbit of the earth around the sun.

The system of optical mirrors collects and directs the concentrated light rays into a curved solar coil located above ground. The curved solar coil is attached to and fixed relative to the system of mirrors so that both the solar coil and the system of mirrors are movably mounted on the tower. Energy from the light rays is absorbed by the solar coil and transferred into the thermal working fluid flowing through a space provided between the solar coil and the enclosure of the solar blackbody waveguide. The energy laden thermal working fluid is removed from the space at an outlet of the enclosure so that it can be used with existing technologies, as previously described.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partially cut away side view of a solar backbody waveguide constructed in accordance with a preferred embodiment of the present invention, showing a tower structure with a movably mounted curved coil and movably mounted system of optical mirrors.

FIG. 2 is a front view of the system of optical mirrors taken along line 2-2 of FIG. 1, showing a rectangular section of the primary parabolic mirror.

FIG. 3 is an enlarged view of the solar blackbody waveguide shown within circle 3 of FIG. 1.

FIG. 4 is an enlarged view of the solar coil of FIG. 3, with arrows to show the path followed by light rays as the light travels within the solar coil.

FIG. 5 is an enlarged view of a prior art linear solar coil such as the one employed in Applicant's prior invention.

FIG. 6 is an enlarged cross sectional view of the solar coil of FIG. 4 taken along line 6-6 showing the solar coil to be made of circular elements and illustrated with optional fins added externally to the circular elements.

FIG. 7 is an enlarged cross sectional view of a first alternate solar coil made of square elements and illustrated with optional fins added externally to the square elements.

FIG. 8 is an enlarged cross sectional view of a second alternate solar coil made of square elements without the addition of optional fins added externally to the square elements.

FIG. 9 is an enlarged cross sectional view of a third alternate solar coil made of diamond shaped elements.

FIG. 10 is an enlarged cross sectional view of a fourth alternate solar coil made of polygon-shaped elements and illustrated with optional fins added external to the polygon-shaped elements.

FIG. 11 is an enlarged cross sectional view of a fifth alternate solar coil made of polygon-shaped elements without the addition of optional fins added externally to the polygon-shaped elements.

FIG. 12 is an enlarged side view of a longitudinal portion of a sixth alternate solar coil made of elements with cross sectional areas that vary as a function of longitudinal position.

FIG. 13 is an enlarged side view of a longitudinal portion of a seventh alternate solar coil made of elements with continuously changing alignment as a function of longitudinal position.

FIG. 14 is a schematic aerial view of a typical installation of a plurality of solar blackbody waveguides employed to provide heat for a combine cycle gas turbine.

FIG. 15 is a schematic aerial view of a typical installation of a plurality of solar blackbody waveguides employed to provide heat for a combine cycle gas turbine shown in association with a wind powered system installed at the same location.

FIG. 16 a partially cut away side view of an alternate solar blackbody waveguide, showing a tower structure with a movably mounted curved coil and movably mounted system of lenses.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT THE INVENTION

Referring now to the drawings and initially to FIG. 1, there is illustrated a solar blackbody waveguide 10 for use in high pressure, high temperature applications for efficient and effective conversion of solar flux to heat energy that is constructed in accordance with a preferred embodiment of the present invention. As illustrated, the invention 10 consists of one or more interconnected towers 12 to efficiently and effectively capture and concentrate energy in the form of solar flux and to efficiently convert this solar energy into useable forms of heat energy. The lower portion 14 of each tower 12 is rigidly fixed to the ground and the upper portion 16 of the tower 12 that supports the system of optical mirrors 18 is movable relative to the lower portion 14 of the tower 12 in order to track the movement of the sun through the sky, as will be more fully described hereafter.

This embodiment of the invention 10 is an improvement to simple-cycle and combined-cycle gas turbine heat engines by preheating the air or thermal working fluid used prior to its introduction into the auxiliary fuel combustion chamber/heat exchanger 20 of the gas turbine 22, as will be more fully described hereafter in association with FIG. 14. However, the invention 10 is not limited to this application and is applicable to numerous other heating cycles using different thermal working fluids or heat transfer fluids other than air. Changes in the thermal fluid could easily be adapted for improvement to the closed, water-based Rankine Cycle of a standard steam turbine, or other commercial or industrial process requiring steam or heated water. Also, as illustrated in FIG. 15, and as will be more fully described hereafter, this invention 10 can be used in association with other energy gathering and concentrating technologies, such as for example wind turbines 24.

Beginning with FIG. 1, the invention will be described in detail. Each tower 12 includes a structural foundation 26 to support the tower 12. The tower 12 is a structural element to support one or more systems of optical mirrors 18 mounted on the tower 12. As shown in FIGS. 14 and 15 and as will be more fully described hereafter, a typical installation of the present invention generally will employ a large number of successively interconnected towers 12.

Referring now to FIGS. 1 and 2, each system of optical mirrors 18 is a modularly designed system of parabolic mirrors constructed out of optical quality reflective materials. The system of optical mirrors 18 uses a reflecting geometry similar to telescope technologies known as a Cassegrain focus. In telescopes that employ Cassegrain focus, parallel incident light rays are reflected from a primary parabolic mirror toward a central focal point incident on a secondary hyperbolic mirror located on the common focal point. The light is then reflected from the secondary hyperbolic mirror to a focal point through a hole in the primary parabolic mirror.

Referring now to FIG. 1, the geometry of the system of optical mirrors 18, which is a modified Cassegrain reflector, is similar to telescopes in that parallel incident light rays 28 are reflected from a primary parabolic mirror 30 toward a common, but not centrally located focal point. In this invention a secondary hyperbolic mirror 32 is used similar to a secondary mirror employed in a telescope. The secondary hyperbolic mirror 32 is secured to an extension of the structural members which support the system of optical mirrors 18 which allows the secondary hyperbolic mirror 32 to be located so that it faces the primary parabolic mirror 30. The light is then reflected from the secondary hyperbolic mirror 32 to a focal point 34 through a hole 36 provided in the primary parabolic mirror 30.

However, the system of optical mirrors 18 is different in some key aspects from the optical systems used in telescopes. The section of the primary parabolic mirror 30 is rectangular rather than circular as in telescopes. This provides optimal land usage and shadowing effects. Further, the primary mirror 30 is not centered, only the upper half of the parabola is used. This prevents the primary mirror 30 from collecting water and snow as the altitude angle approaches vertical as would happen with a dish style mirror used in a telescope.

Once the concentrated light rays 40 pass through the hole 36 of the primary parabolic mirror 30, they enter into the short optical waveguide 42 which will direct the concentrated light rays 40 into a solar coil 44 located within an enclosure 46 of the solar blackbody waveguide 10. From the point that the concentrated light rays 40 enter the short optical waveguide 42, the path of the concentrated light rays 40 contained within the solar blackbody waveguide 10 will be referred to as concentrated light rays 40 regardless of whether the light rays are parallel, converging or diverging.

The short optical waveguide 42 is a flared, external extension of the solar coil 44 that penetrates through the enclosure 46 containing the thermal fluid. This external extension 42 is designed to capture any stray concentrated light rays 40 and make sure they are directed into the coil 44. This short optical waveguide 42 is internally coated or mirrored to be highly reflective so that minimal energy is lost in any reflections that occur outside of the enclosure 46. In addition, the hyperbolic secondary mirror 32 preferably reflects the concentrated light rays 40 to a focal point 34 that is internal to the solar coil 44 and within the interior of the enclosure 46, making the short optical waveguide 42 only necessary for capture of stray concentrated light rays 40.

Due to the convergence of the concentrated light rays 40 and the internally mirrored surfaced of the short optical waveguide 42, the concentrated light rays 40 arrive at the entrance to the solar blackbody waveguide 10, as illustrated in FIGS. 1, 3, and 4, without substantive loss of energy.

As illustrated in FIG. 1, each tower 12 is provided with a dual-axis tracking mechanism 52. Dual-axis tracking is necessary because of the different angles that the sun makes with the horizon due to the variation of the seasons and daily movement of the sun through the sky. The dual-axis tracking mechanism 52 continually repositions the system of optical mirrors 18 so that it is always facing toward the sun at the optimum orientation to receive the parallel incident light rays 28 emanating from the sun.

The dual-axis tracking mechanism 52 consists of a first axis or altitude drive motor 54 for driving the gear drive mechanism 58 for tilting the altitude angle of the system of optical mirrors 18 relative to the horizon 56 so that the system of optical mirrors 18 directly faces the sun during all seasons of the year and second axis or azimuth drive motor 60 for rotating the system of optical mirrors 18 so that the system of optical mirrors 18 tracks the sun through its daily movement through the sky. Both of the first axis or altitude drive motor 54 and the second axis or azimuth drive motor 60 are continuously controlled to maintain the system of optical mirrors 18 at approximately a 90 degree orientation to the sun's path as the earth makes its daily rotation on its axis and also makes its annual orbit around the sun.

Although not specifically illustrated, the proper tracking angles, both azimuth and altitude, are calculated from the latitude and longitude of the tower's location via a small programmable logic controller (PLC) that controls the operation of the electric motors 54 and 60. The dual-axis tracking mechanism 52 permits the tower 12 to track the hourly movement of the sun through the sky from east to west so that the system of optical mirrors 18 always faces the sun. The PLC will generally be located remotely from the tower 12 and will serve to operate the dual-axis tracking mechanisms 52 on one or more towers 12 located at an installation of the invention. As taught in Applicant's U.S. Pat. No. 6,899,097, optical angle readers will preferably be employed to track the actual azimuth and altitude angles of the system of optical mirrors 18 relative to the tower 12. The optical angle readers use an optical compact disk or CD reader to read precise angular data encoded on a compact disk or CD to keep track of the actual azimuth and altitude angles of the system of optical mirrors 18. This angular data is used in a feedback control loop to control the position of the azimuth and altitude angles of the dual-axis tracking mechanism 52 and the position of the attached system of optical mirrors 18.

After passing the short optical waveguide 42, the concentrated light rays 40 enter the solar coil 44. As illustrated in FIG. 4, concentrated light rays 40 continue traveling in the initial straight section 48 of the solar coil 44 until they encounter an interior wall 62 of the remaining curved section 50 of the solar coil 44. When the concentrated light rays 40 encounter the interior wall 62, the concentrated light rays 40 bounce off of the interior wall 62 and continue through the coil 44, repeatedly bouncing off of the interior wall 62. Each time the concentrated light rays 40 bounce off of the interior wall 62, some of the light rays' energy is lost in the form of heat that is transferred to the interior wall 62. Because the curved section 50 of the solar coil 44 is shaped into a continuous loop and does not have any exit for the concentrated light rays 40, the concentrated light rays 40 will continue to bounce off of the interior walls 62 until all of their energy is released in the form of heat to the interior walls 62 of the solar coil 44. This results in a tremendous amount of heat being transferred into the interior walls 62 of the solar coil 44. This continuous loop configuration of the curved section 50 of the solar coil 44 should be compared to the linear solar coil configuration 44P of the prior art solar blackbody waveguide 10P illustrated in FIG. 5. Because the prior art linear solar coil configuration 44P was finite in length, it did not insure that all of the energy from the light rays 40 was released in the form of heat to the walls of the pipe 44P. Also, the prior art linear solar coil configuration 44P was extremely long and therefore required much more pipe and much more space as compared to the much more compact size of the present curved solar coil 44.

The developed heat is conducted from the interior walls 62 to the external or exterior walls 68 of the solar coil 44 and into a heat transfer fluid that flows through the enclosure 46 that surrounds the solar coil 44. The heat transfer fluid is illustrated in the drawings by arrows associated with the numeral 64. Unheated heat transfer fluid is denoted in the drawings as 64U and heated heat transfer fluid is denoted in the drawings as 64H. Exhaust of the heat transfer fluid from the system is denoted in the drawings as 64E. Thus the solar blackbody waveguide 10 functions to first convert the potential energy contained in the light rays 40 to thermal energy and then serves as a heat exchanger by transferring the heat from the interior wall 62 of the solar coil 44, through to the external wall 68 of the solar coil 44 and into the heat transfer fluid 64 that is flowing through an enclosed space 66 provided between the exterior walls 68 of the solar coil 44 and an interior wall 70 of the enclosure 46.

As illustrated in FIG. 3, the enclosure 46 is provided with an inlet 72 for admitting unheated heat transfer fluid 64U into the enclosed space 66. The enclosure 46 is also provided with an outlet 74 through which the now heated heat transfer fluid 64H exits the enclosed space 66 of the enclosure 46. As the heat transfer fluid 64 enters the enclosure 46 via the inlet 72, it encounters baffles 76 that are provided within the enclosed space 66 that cause the heat transfer fluid 64 to move through the enclosed space 66 and exit via the outlet 74 in a first-in, first-out flow pattern. The arrangement of the baffles 76 force the heat transfer fluid 64 to pass around the exterior walls 68 of the solar coil 44 where heat is transferred into the heat transfer fluid 64 from the heated exterior walls 68 of the solar coil 44. Thus, heat is added to the heat transfer fluid 64 as it passes through the enclosure 46.

As illustrated in FIGS. 14 and 15, a single air compressor 80 for the heat transfer fluid 64 can provide heat transfer fluid 64 to a plurality of solar blackbody waveguides 10, and a plurality of solar blackbody waveguides 10 can provide a single heated heat transfer fluid stream 64H that can be connected to an auxiliary fuel combustion chamber/heat exchanger 20 providing heat to a combined cycle gas turbine 22. This is done by providing an inlet header 82 that is attached to a single air compressor 80 and to the plurality of solar blackbody waveguides 10 and by providing an outlet header 84 that attaches to the plurality of solar blackbody waveguides 10 and to the auxiliary fuel combustion chamber/heat exchanger 20, then to the combined cycle gas turbine 22. The inlet header 82 provides an unheated heat transfer stream 64U that provides heat transfer fluid 64 to the plurality of solar blackbody waveguides 10. The outlet header 84 receives the heated heat transfer fluid 64 from the plurality of solar blackbody waveguides 10 to form a heated heat transfer stream 64H that is then supplied to the auxiliary fuel combustion chamber/heat exchanger 20 and then to a combined cycle gas turbine 22.

As further illustrated in FIG. 14, the solar blackbody waveguides 10 are preferably spaced apart from each other and arranged in rows 86A, 86B, 86C, 86D, 86E, 86F, 86G, etc. of interconnected solar blackbody waveguides 10 that extend between the inlet header 82 and the outlet header 84. The rows 86A, 86B, 86C, 86D, 86E, 86F, 86G, etc. of solar blackbody waveguides 10 are interconnected via their heat transfer lines 88. A first heat transfer line 88 in each row 86A, 86B, 86C, 86D, 86E, 86F, 86G, etc. connects to the inlet header 82 and to the enclosure inlet 72 of the first solar blackbody waveguide. Also the last heat transfer line 88 in each row 86A, 86B, 86C, 86D, 86E, 86F, 86G, etc. connects to the enclosure outlet 74 of the last solar blackbody waveguide 10 in that row 86A, 86B, 86C, 86D, 86E, 86F, 86G, etc. and to the outlet header 84. Each of the other heat transfer lines 88 extends from the enclosure outlet 74 of an adjacent solar blackbody waveguide 10 to an enclosure inlet 72 of an adjacent solar blackbody waveguide 10 located downstream in the row's heat transfer fluid flow path. Thus the heat transfer lines 88 provide heat transfer fluid from the inlet header 82 through each row 86A, 86B, 86C, 86D, 86E, 86F, 86G, etc. of solar blackbody waveguides 10 and return the now heated heat transfer fluid from all on the rows 86A, 86B, 86C, 86D, 86E, 86F, 86G, etc. to the outlet header 84. By connecting the solar blackbody waveguides 10 in this manner, the collective energy from all of the solar blackbody waveguides 10 can be employed to preheat combustion air as the heat transfer fluid 64 that will be fed to the auxiliary combustion chamber/heat exchanger 20 of a combine cycle gas turbine 22.

The enclosure 46 is preferably insulated by adding a high temperature refractory insulation system 90 to the exterior surface 92 of the enclosure 46 to minimize heat loss. The heat transfer lines 88 are similarly insulated.

The solar coil 44 works like a waveguide for the concentrated light rays 40 but is not lossless. Instead, the concentrated light rays 40 reflect off of the interior walls 62 of the metal solar coil 44, losing some energy to the solar coil 44 on each reflection. This energy is absorbed by the solar coil 44 causing the temperature of the solar coil 44 to rise rapidly. Heat travels from the interior walls 62 through the solar coil 44 to the exterior walls 68 of the solar coil 44. From the exterior walls 68, the heat transfers into the heat transfer fluid or thermal working fluid 64 such as air or water passing over the exterior walls 68 of the solar coil 44 within the enclosed space 66 provided between the solar coil 44 and the enclosure 46. As illustrated in FIG. 6, since thermal conduction is the primary heat transfer mechanism, the solar coil 44 may optionally be equipped externally with thermal fins 94 to increase the effective surface area of the solar coil 44 and thus enhance the heat transfer from the solar coil 44 into the heat transfer or thermal working fluid 64. Thermal fins 94 are illustrated in FIGS. 6, 7, and 10 for various alternate cross sectional variations of the coil 44 configuration. Although the cross sectional configuration of the solar coil illustrated in FIGS. 4 and 6 is circular, the invention is not so limited. As illustrated in FIGS. 7 through 11, the cross sectional configuration of the solar coil 44 can alternately be different from circular. The cross sectional configuration of a first alternate solar coil 44′ is square, as illustrated in FIG. 7 where the solar coil 44 is shown provided with thermal fins 94 and in FIG. 8 where the solar coil 44 is shown without fins 94. Alternately, the cross sectional configuration of a second alternate solar coil 44″ is diamond shaped, as illustrated in FIG. 9 and can be made with or without thermal fins 94. As illustrated in FIGS. 10 and 11, the cross sectional configuration of a third alternate solar coil 44′″ can alternately be a regular polygon and can be made with fins 94, as shown in FIG. 10 or without fins 94, as illustrated in FIG. 11. Although several cross sectional configurations have been illustrated for the solar coil 44, the invention is not so limited and a variety of other suitable cross sectional configurations are possible. Also, as illustrated in FIG. 12, the solar coil 44 need not be uniform in cross section along its length. And as illustrated in FIG. 13, the solar coil 44 need not be uniform in alignment, but can vary in alignment continuously along its length, such as the curved, coiled configuration of the solar coil 44 shown in FIG. 4.

In essence, the solar coil 44 acts as a solar power heating coil within the enclosure 46. Due to the geometry of the solar coil 44, it acts as a lossy, blackbody waveguide absorbing nearly one hundred percent (100%) of the solar energy collected and injected into the coil 44 in the form of concentrated light rays 40. The coil 44 is preferably constructed of high temperature, poly-molybdenum steel suitable for operation at temperatures above 1200° F.

FIG. 14 illustrates one possible use for the present invention. FIG. 14 shows the invention used as a preheater for a combined cycle gas turbine 22. The preheater is that portion of FIG. 14 enclosed within the box defined by the broken line associated with the numeral 96. The compression stage, represented in FIG. 14 by the air compressor 80, of the standard Brayton cycle gas-turbine is detached and the invention with its solar collection towers 12 and solar coils 44 are introduced as an air preheater for the air entering the auxiliary fuel combustion chamber/heat exchanger 20. This preheating effect can be used to reduce the amount of natural gas or other fuel 78 burned in the production of electricity or other co-generation processes. The detached air compressor 80 that supplies compressed air to the inlet header 82 can be a fan compressor type similar to those used in standard gas turbines, a screw type compressor similar to those used in natural gas pipelines, or a piston type compressor if high pressures are required. Since overall turbine efficiency is related to the compression ratio, there may be distinct advantages in using compressors 80 that are able to attain higher working pressures than possible with current turbine compressors.

Other components of existing combine cycle technology illustrated in FIG. 14 are the air or gas turbine 22, a steam turbine 100, a heat recovery steam generator 102, a water recirculation pump 104, and a steam condenser 106. These existing technologies are leveraged with modifications for higher compression ratios and higher efficiencies permitted by the higher operating pressures and higher operating temperatures.

Due to the variable nature of the energy input by the preheater 96 in FIG. 14, a fuel supply controller (not illustrated) is used to modulate the fuel 78 flowing to the auxiliary fuel combustion chamber/heat exchanger 20 to provide enough differential power to maintain consistent power output from the generator system that attaches to the air and steam turbines 22 and 100. In order for the fuel supply controller to function, it receives information from the generator system on the amount of electricity being dispatched and receives information on the amount of heat being produced by the preheater 96 prior to combustion of fuel 78. Thus when the preheater 96 is providing more heat, less fuel 78 needs to be supplied to the auxiliary fuel combustion chamber/heat exchanger 20 and when the preheater 96 is providing less heat, more fuel 78 must be supplied. As is typical in the steam or Rankine cycle portion of existing combined cycle plants, water recirculation pump 104 recirculates water from the steam condenser 106 and through the heat recovery steam generator 102 to provide steam for the steam turbine 100.

FIG. 15 illustrates another possible use for the present invention. FIG. 15 shows the same installation as illustrated in FIG. 14 except that this installation includes wind turbines 24 of a separate wind powered generation system that is installed on the same land where the solar collection towers 12 of the present invention are installed. These two types of technology are compatible and allows for dual usage of land for both solar and wind power collection and generation. Although FIG. 15 illustrates the compatibility of the present invention with a wind powered generation system, the invention is not so limited as the present invention may also be compatible with other types of power generation systems, thus allowing for dual land usage.

Each of the uses described above involve removing the transfer fluid 64 from the enclosure 46 for use in providing heat to a system located outside the enclosure 46. The invention is not so limited and the transfer fluid 64 can be used within the enclosure 46. For example, the enclosure 46 could be a building or other type of structure, the heat transfer fluid 64 could be air, and the solar blackbody waveguide 10 could be used in conjunction with the building's HVAC system as a means of heating the air within the interior of the enclosure 46 without the need to remove the air from the building.

FIG. 16 shows an alternate embodiment 10A of the present invention. The alternate embodiment 10A employs a system of lenses 18A instead of the system of optical mirrors 18 previously described in order to collect and concentrate parallel incident light rays 28. As illustrated in FIG. 16, the system of lenses 18A might consist of a primary convex lens 18B which directs the light to a secondary concave lens 18C which in turn directs the now concentrated light rays 40 to the solar coil 44 in a manner similar to that previously described for the preferred embodiment 10. If the concentrated light rays 40 are focused on a focal point 34 located inside the solar coil 44, this eliminates the need for the short optical waveguide 42.

While the invention has been described with a certain degree of particularity, it is manifest that many changes may be made in the details of construction and the arrangement of components without departing from the spirit and scope of this disclosure. It is understood that the invention is not limited to the embodiments set forth herein for the purposes of exemplification, but is to be limited only by the scope of the attached claim or claims, including the full range of equivalency to which each element thereof is entitled.

Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US8152339May 1, 2008Apr 10, 2012Morgan Solar Inc.Illumination device
US8230851May 16, 2011Jul 31, 2012Genie Lens Technology, LLCTracking fiber optic wafer concentrator
US20140133041 *Oct 8, 2012May 15, 2014Ut-Battelle, Llc.Modular off-axis fiber optic solar concentrator
WO2010040053A1 *Oct 2, 2009Apr 8, 2010Richard Morris KnoxSolar energy concentrator
WO2010048553A2 *Oct 23, 2009Apr 29, 2010Chasse Annette PWindow system for a solar receiver and method and solar receiver system employing same
WO2011038127A2 *Sep 23, 2010Mar 31, 2011Genie Lens Technologies LlcTracking fiber optic wafer concentrator
WO2013134576A1 *Mar 8, 2013Sep 12, 2013Perryman Virgil Dewitt JrSolar energy collection and storage
Classifications
U.S. Classification126/583
International ClassificationF24J2/40
Cooperative ClassificationY02E10/44, F24J2/18, Y02E10/41, F05B2240/96, F03G6/064, F03D9/007, F24J2/14, F24J2002/5462, Y02E10/72, Y02E10/465, F24J2/07, F24J2/06, F02C1/05, F24J2/542, Y02E10/47, F24J2/067, F24J2002/003
European ClassificationF03G6/06G, F24J2/54C2, F03D9/00E, F24J2/07, F24J2/06, F24J2/18, F02C1/05