Abstract:
The present disclosure provides systems and methods for the collection and concentration of solar thermal energy and the exchanging of this concentrated solar thermal energy into transportable and usable heat energy in a medium such as water, oil or molten salts.

Description:
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 
       [0001]    This invention relates generally to the field of solar energy conversion and more particularly to a concentrating solar thermal energy receiver. 
         [0002]    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. 
         [0003]    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 
       [0004]    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 
         [0005]    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: 
           [0006]      FIG. 1  illustrates a right side view of one embodiment of a solar thermal energy antenna in accordance with the present disclosure; 
           [0007]      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; 
           [0008]      FIG. 3  illustrates a right side view of one embodiment of a solar thermal energy receiver and exchanger in accordance with the present disclosure; 
           [0009]      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 
       [0010]    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. 
         [0011]    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. 
         [0012]    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 . 
         [0013]    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. 
         [0014]    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. 
         [0015]    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.