CROSS-REFERENCE TO RELATED APPLICATIONS—Not Applicable
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT—Not Applicable.
NAMES OF PARTIES TO A JOINT RESEARCH AGREEMENT—Not Applicable.
REFERENCE TO A SEQUENCE LISTING, A TABLE OR A COMPUTER PROGRAM, LISTING COMPACT DISC APPENDIX—Not Applicable
STATEMENT REGARDING PRIOR DISCLOSURES BY AN INVENTOR OR JOINT INVENTOR—Not Applicable
BACKGROUND OF THE INVENTION
This invention relates generally to the field of solar energy conversion and more particularly to a concentrating solar thermal energy receiver.
Devices for solar energy collection and conversion can be classified into concentrating types and non-concentrating types. Both concentrating and non-concentrating types are used for converting solar energy into either electrical energy directly through the photovoltaic effect or into heat energy. Non-concentrating types intercept parallel unconcentrated rays of the sun with an array of detection or receiving devices such as a solar panel of photovoltaic cells or hot water pipes, for example. The output is a direct function of the area of the array. A concentrating type of solar energy collector focuses the energy rays using, e.g., a parabolic reflector, a plurality of reflectors, or a lens assembly to concentrate the rays, creating a more intense beam of energy. The beam is concentrated to improve the efficiency of conversion of solar radiation to electricity or to increase the amount of heat energy collected from the solar radiation to provide for heating of water and so forth. In a conventional concentrating solar energy receiver, the incident solar radiation is typically focused at a point from a circular parabolic reflector (e.g., a dish-shaped reflector), along a focal line from a linear parabolic shaped reflector (e.g., parabolic trough), along a focal line from a plurality of linear lenses (e.g., Fresnel lens), or to a central target from a plurality of reflectors (e.g., heliostats). These concentrating type systems may be a single reflector or a plurality of reflectors that create a primary reflector system. In a prior art example, such as disclosed in U.S. Pat. No. 6,818,818 issued to Bernard F. Bareis, an aspect of an alternative embodiment of the invention is described where a secondary reflector is positioned in front of the primary parabolic reflector. In this device the secondary reflector redirects the solar energy collected by the primary reflector back toward the primary reflector where the concentrated solar energy is utilized by a reception surface coupled to a thermal cycle engine whose output drives and electrical generator.
However, even conventional solar thermal concentrating devices require improvements for two reasons. First, the U.S. Energy Information Administration lists solar thermal as the most expensive technology with which to generate electricity (Source: U.S. Energy Information Administration, Annual Energy Outlook 2014 Early Release, December 2013, DOE/EIA-0383ER(2014). Costs for these solar thermal systems are high due to a poor capacity factor, the large amount of land required to build a system, the complexity of the systems, and both their size and complexity lead to higher fixed operation and maintenance costs. Secondly, systems with a secondary reflector discuss either photovoltaic cells or a striker plate to power a thermal engine as the ultimate use of the concentrated solar energy, and ignore the potential of exchanging the solar thermal energy to heat energy in a fluid medium.
BRIEF SUMMARY OF THE INVENTION
A dual reflector antenna with autonomous tracking capability that collects solar thermal energy, concentrates the collected thermal energy, and exchanges the concentrated solar thermal energy to heat energy in a medium such as water, oil, or molten salts.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
For a more complete understanding of the present invention and the advantages thereof, reference is now made to the following description taken in conjunction with the accompanying Drawings in which:
FIG. 1 illustrates a right side view of one embodiment of a solar thermal energy antenna in accordance with the present disclosure;
FIG. 2 illustrates a right side cross section view at the azimuth axis of one embodiment of a solar thermal energy antenna in accordance with the present disclosure;
FIG. 3 illustrates a right side view of one embodiment of a solar thermal energy receiver and exchanger in accordance with the present disclosure;
FIG. 4 illustrates a right side cross section view at the centerline of one embodiment of a solar thermal energy receiver and exchanger.
DETAILED DESCRIPTION OF THE INVENTION
Referring now to FIG. 1, there is illustrated one embodiment of a solar thermal energy antenna according to the present disclosure. The solar thermal energy antenna 100 includes a pedestal 110 that may have penetrations for conduits and ports for accessing the inside of the pedestal and has flanges at the top and bottom that may internal or external to the pedestal where the bottom flange may be attached to a foundation set in the ground or a platform 120. The top flange of the pedestal 110 is connected to the outer race of a bearing and ring gear assembly 130. The inner race of the bearing and ring gear assembly 130 is connected to the turning head assembly 140 and allows the turning head assembly 140 to rotate 150 about the azimuth axis of the antenna 160. The turning head assembly 140 is driven by an electric motor 170 connected to a ninety-degree gearbox 180 connected to a planetary gearbox 190 connected to a pinion gear 200 that meshes with the bearing and ring gear assembly 130. Another aspect of the system used to drive the turning head is an electric motor connected to a tee gearbox where one output of this gear box is connected by a shaft to a ninety-degree gearbox connected to a planetary gearbox connected to a pinion gear that meshes with the bearing and ring gear assembly and the second out put of the tee gearbox is connected to a ninety-degree gearbox connected to a planetary gearbox connected to a pinion gear that meshes with the bearing and ring gear assembly. This aspect would allow the two pinion gears to be set against the bearing and ring gear assembly in opposite directions thereby eliminating backlash in the drive system. The turning head assembly 140 provides for attachment of the reflector hub assembly 210 at two points on the same axis. The reflector hub assembly 210 is open in the center and provides for the installation of equipment within the reflector hub assembly 210 that may protrude through the reflector hub assembly 210. The attachment of the reflector hub assembly 210 to the turning head assembly 140 is made in such a way as to create a hinge that becomes the elevation axis 220 of the reflector hub assembly 210 and allows the reflector hub assembly to rotate 230 about the elevation axis. The elevation jack 240 that is attached to the reflector hub assembly 210 and the turning head assembly 140 drives the reflector hub assembly 210. Attachment of the elevation jack 240 to the turning head assembly 140 and the reflector hub assembly 210 is made in such a way as to allow freedom of movement of the elevation jack 240 as it extends and retract while maintaining nominal positioning of the elevation jack 240. An electric motor and gearbox assembly 250 drives the elevation jack 240. A plurality of truss assemblies 260 is attached to the reflector hub assembly 210 in a radial fashion. The truss assemblies 260 are interconnected with a plurality of struts 270 in order to provide additional rigidity of the structure formed by the truss assemblies 260. A plurality of reflector panels 280 is attached to the truss assemblies 260 and forms the parabolic dish that is the main reflector 290. The reflective surface of the reflector panels 280 may be polished metal, applied reflective film, or mirrors. The main reflector 290 collects solar energy radiation 300 in the form of a plurality of incident rays. The attachment points of the reflector panels 280 to the truss assemblies 260 are such that they provide adjustment of the individual reflector panel 280 in order to form an optically homogeneous reflective surface of the entire main reflector 290. A secondary reflector 310 is attached to a support assembly 320 and suspended if front of the primary reflector by a plurality of struts 330 that attach to the support structure 320 and select truss assemblies 260. The reflective surface of the secondary reflector 310 may be polished metal, applied reflective film, or mirrors. The attachment points of the secondary reflector 310 to the support assembly 320 are such that they provide adjustment of the secondary reflector 310 for alignment with the main reflector 290. The secondary reflector may be either a hyperbolic shape thus creating a Cassegrain type of antenna or a parabolic shape thus creating a Gregorian type of antenna. A solar thermal energy receiver and exchanger 500 is mounted inside of the reflector hub assembly 210. A cool fluid such as water, oil, or molten salt is provided to the solar thermal energy receiver and exchanger from a supply line 340 and exchanges concentrated thermal energy to heat energy in the fluid, and the heated fluid is then sent to do useful work as heat energy via a return line 350. A plurality of photo sensors 360 are attached to the end tips of select truss assemblies 260 aligned in parallel to the solar energy radiation 300 and provide signals to the antenna control system that in turn provides signals to the azimuth electric motor 170 and elevation electric motor and gearbox assembly 250 to autonomously maintain the axis of the main reflector 290 parallel to the solar energy radiation 300. The mechanical configuration of the embodiment described is commonly known as a pedestal type of antenna. An alternative embodiment can be a mechanical configuration known as a king post type of antenna. Manufacture and use of an antenna such as described herein will be readily apparent to those in the field of satellite communications and in particular large satellite communication ground station antennas.
Referring now to FIG. 2, there is illustrated a cross section view of an embodiment of a solar thermal energy antenna 100 as previously described in FIG. 1. Direct parallel solar energy radiation 300 from the sun is collected by the main reflector 290 and concentrated to the main reflector focal point 370. Prior to reaching the main reflector focal point 370 the concentrated solar energy radiation is intercepted by the secondary reflector 310 and reflected back toward the center of the main reflector 290. The concentrated solar energy radiation that is collected and reflected by the secondary reflector 310 is further concentrated to the secondary reflector focal point 380. The secondary reflector focal point 380 is located within the solar thermal energy receiver and exchanger 500 where the concentrated solar thermal energy is exchanged into heat energy.
Referring now to FIG. 3, there is illustrated a side view of a solar thermal energy receiver and exchanger 500 that is attached to the center of the reflector hub assembly 210 shown in FIG. 1 and FIG. 2. Concentrated solar energy radiation 21 enters the solar thermal energy receiver and exchanger 500 through a lens 510 and is absorbed by a cylinder that is an integral part of the cylinder and front plate assembly 520. A casing 530 is attached to the cylinder and front plate assembly 520. A back plate 540 is attached to the casing 530. The connection of the lens 510, cylinder and front plate assembly 520, casing 530 and back plate 540 is such that they form a sealed assembly. The ends of the coiled tube 550 penetrate through the back plate 540 and are connected to the supply line 340 and return line 350 shown in FIG. 1 and FIG. 2.
Referring now to FIG. 4., there is illustrated a cross section view of the embodiment of a solar thermal energy receiver and exchanger 500 as described in FIG. 4. Concentrated solar energy radiation 300 enters the solar thermal energy receiver and exchanger 500 through a lens 510 passing through the secondary reflector focal point 380 then striking the closed end of the cylinder and front plate assembly 520. The concentrated solar energy radiation 300 that strikes the closed end of the cylinder and front plate assembly 520 is converted and stored as heat energy within the cylinder and front plate assembly 520. Heat energy stored in the cylinder and front plate assembly 520 is transferred and stored in molten salts 560 that fill the chamber of the solar thermal energy receiver and exchanger 500. Heat energy in the molten salts 560 is transferred to a fluid medium that travels through a coiled tube 550. The coiled tube 550 has an outer winding and an inner winding. Cool fluid is brought to the coiled tube 550 from the supply line 340. As the fluid travels through the coiled tube 550, heat energy contained in the molten salts 560 is transferred to the fluid medium. The heated fluid then travels through the return line 350 where it can be utilized for useful work for example, to create steam that drives a turbine that produces electricity.
Other features may be incorporated in the specific implementation of the solar thermal energy antenna of the present disclosure. For example, the reflectors may include one or more lightening rods or arresting devices to prevent lightening damage, one or more aircraft warning lights may be added as required by regulatory agencies, heating systems may be included to prevent icing of the reflectors, work platforms and access ladders or stairs may be included, one or more sensors and or switches may be included to provide for the safe operation of the solar thermal energy antenna.
Although the preferred embodiment has been described in detail, it should be understood that various changes, substitutions, and alterations can be made therein without departing from the spirit and scope of the invention as defined by the appended claims.
Patent Application
20170074547
