Abstract:
The solar concentrator includes a base with a support frame that is rotatably connected thereto. A torsion box is tiltably mounted to the support frame to provide a wide range of movement of the torsion box and the finish surface thereon, which is preferably of a single plane parabolic shape that carries linear mirror strips. A receiver is mounted above the surface of the mirror strips at the focus of the parabola by a bracket to optimize reflection of radiation thereto. Plumbing transports liquid, such as water, through the receiver for heating thereof for various purposes, such as water desalinization. Thus, the solar concentrator is an optimized low cost and easy to manufacture solar concentrator.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application is related to and claims priority from earlier filed provisional patent application Ser. No. 61/483,141, filed May 6, 2011, the entire contents thereof is incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    This invention relates to power generation systems. In particular, the invention relates to a solar thermal power plant using solar heat energy in a direct steam generation (DSG) process, wherein a liquid phase of a phase changing fluid (e.g. water) is provided by a pressure vessel to a boiler tube where concentrated solar radiation heating takes place, and a gaseous phase of a phase changing fluid (e.g. steam) is cycled back to the pressure vessel, so as to enable flow control under rapidly varying solar heating transients and two-phase working fluid instability conditions, and to enable heat energy storage in the pressure vessel for later use in the production of electrical or mechanical power as well as space/water heating. 
         [0003]    Solar thermal power plants and systems using DSG processes are known for use in various applications, including for example powering a steam turbine and generating electricity. DSG processes have particular application in the purification of water, desalinization and generation of electricity, for example. DSG systems typically use solar concentrators or collectors, such as parabolic trough collectors or dish collectors known in the art, to focus solar radiation onto a vessel or tube in which, for example, water is flowed or otherwise present, to heat the water into steam. In such systems, work is then typically produced by expanding the steam in an expander, such as a turbine, after which the working fluid may be condensed in a condenser for recirculation in the case of closed systems, or expelled in the case of open systems. 
         [0004]    It is well known in the industry that a large portion of the cost and effort in manufacture is directed to the construction of the solar concentrator body itself. This is because it is critical for the solar concentrator to be as stable and vibration-proof as possible so that it may provide a solid substrate base for receiving and supporting the important mirrored surface thereon. It is well known in the art to provide a solar concentrator in the form of a steel exoskeleton that carries cement thereon in the form of the desired parabolic shape. The surface of the cement face of the concentrator is coated with the desire mirrored glass material to provide the needed reflectivity to direct radiation to the fluid filled tubing or chamber for heating. As can be understood, this custom mirrored glass is very expensive and the large cement base is extremely heavy. As a result, these prior art solar concentrators that are known in the art are very expensive and cumbersome. 
         [0005]    In summary, there is therefore a need for a DSG type solar thermal power generation system with a solar concentrator that is less expensive and cumbersome than prior art solar concentrator yet still provides superior radiation directing performance. There is a need for a solid structure that is rigid and can hold its shape yet still provides the needed mirrored surfaces for reflection of radiation, as required. There is a further need for a solar concentrator that has a long shelf life with relatively low tolerance. There is a need for a solar concentrator that is easier and quicker to manufacture and assemble compared to prior art concentrators. Moreover, there is a need for a solar concentrator that is durable and non-corrosive. There is a need to replace expensive mirrors with low iron float mirrors. Finally, there is a need to replace prior art steel exoskeletons with fiberglass composite materials. 
       SUMMARY OF THE INVENTION 
       [0006]    The present invention preserves the advantages of prior art solar concentrators for the purposes of making direct steam. In addition, it provides new advantages not found in currently available solar concentrators and overcomes many disadvantages of such currently available solar concentrators. 
         [0007]    The present invention provides a solar concentrator that includes a base with a support frame that is rotatably connected thereto. A torsion box is tiltably mounted to the support frame to provide a wide range of movement of the torsion box and the finish surface thereon, which is preferably of a single plane parabolic shape that carries linear mirror strips. A receiver is mounted above the surface of the mirror strips at the focus of the parabola by a bracket to optimize reflection of radiation thereto. Plumbing transports fluid through the receiver for heating thereof to provide an optimized low cost and easy to manufacture solar concentrator. 
         [0008]    It is an object of the present invention to provide a novel and unique solar concentrator that is less expensive to manufacture than prior solar concentrators. 
         [0009]    There is a further object of the present invention to provide a solar concentrator that is lighter in weight and easier to manufacture and assemble. 
         [0010]    Another object of the present is to provide a solar concentrator that can be positioned as needed, such as in two axes of rotation, for optimal tracking of the sun. 
         [0011]    A further object of the present invention is to provide a solar concentrator that employs standard commodity parts and components to help reduce cost of construction of the solar concentrator. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    The novel features which are characteristic of the present invention are set forth in the appended claims. However, the invention&#39;s preferred embodiments, together with further objects and attendant advantages, will be best understood by reference to the following detailed description taken in connection with the accompanying drawings in which: 
           [0013]      FIG. 1  is a front perspective view of the solar concentrator of the present invention; 
           [0014]      FIG. 2  is a front view of the solar concentrator of the present invention; 
           [0015]      FIG. 3  is a front perspective view of the solar concentrator of the present invention prior to installation of the glass mirror strips; 
           [0016]      FIG. 4  is a front view of the solar concentrator of the present invention prior to installation of the glass mirror strips; 
           [0017]      FIG. 5  is a close-up front perspective view with one glass strip installed on the top surface of the solar concentrator; 
           [0018]      FIG. 6  is a side view of the solar concentrator of the present invention with receiver installed; 
           [0019]      FIG. 7  is a top view of the solar concentrator of the present invention showing the array of mirror strips; and 
           [0020]      FIG. 8  is a representational view of the two different directions of movement of the solar concentrator of the present invention. 
           [0021]      FIG. 9  is a side view of the solar concentrator of the present invention in a first tilted gimbal position; 
           [0022]      FIG. 10  is a side view of the solar concentrator of the present invention in a second tilted gimbal position; 
           [0023]      FIG. 11  is a side view of the solar concentrator of the present invention in a third tilted gimbal position; 
           [0024]      FIG. 12  is a rear view of the solar concentrator of the present invention showing the piston for controlling gimbal tilt; and 
           [0025]      FIG. 13  is a front perspective view of the base with support for the support frame. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0026]    Turning first to  FIGS. 1 and 2 , a front perspective and front view of the solar concentrator  10  of the present invention is shown. The solar concentrator  10  includes a base  12  with a support frame  14  rotatably connected thereto to permit rotation of the solar concentrator  10  about an axis that is substantially perpendicular to the ground  16 . The support frame  14  includes two arms  18  with only one shown in the figures with the opposing arm being a mirror image thereof. A torsion box  20  is pivotally mounted to the support frame  14  via the arms  18 , namely via pins  22  emanating from opposing sides of the torsion box  20  that pivotally engage with respective apertures  24  through the free ends of the arms  18 . While this configuration is preferred to enable pivoting, it may be reversed with pins on the support arms  18  and apertures on the torsion box  20  or another structure and still be within the scope of the present invention. 
         [0027]    As will be described in detail below, the torsion box  20  is parabolic through one plane is made of hollow fiberglass and carries an array of glass mirror strips  26  thereon. A receiver  28  is mounted at the focal point of the parabolic-shaped torsion box  20  to focus reflected light for heating of fluid passing through the receiver. Water is preferably used for the fluid. Receiver support/bracket  30  is employed to position the receiver  28  where desired and plumbing  32  is used to transport fluid passing through the receiver  28 . The receiver support  30  may be, for example, a 40 inch steel or carbon fiber I-beam. The receiver  28  may be blackened copper pipe with a Pyrex jacket and a liner trip of a triple junction photovoltaic cell. Such a configuration enables the receiver  28  to be elevated above the surface  21  of the solar concentrator  10  at the precise location of the parabolic focal point (i.e. liner focus) to optimize reflection of radiation from the surface of the solar concentrator  10 . 
         [0028]    Turning now to  FIG. 3 , a front perspective view of the solar concentrator  10  of the present invention is shown prior to installation of the glass mirror strips  26 .  FIG. 4  shows a front view thereof. A torsion box  20 , preferably fiberglass, is provided as a substrate to support the fiberglass finish  21  thereon. The torsion box  20  provides a rigid structure so that the overall shape of the solar concentrator  10  is maintained. The torsion box  20  can be filled with sand or other material (not shown) to add weight thereto to help reduce undesirable vibration due to wind, and the like. Preferably, the solar concentrator  10  has a parabolic shape in one direction, i.e. a curved shape in one plane rather than a circular paraboloid shape where the surface is defined by a parabola traveling along its axis one in more than one plane. The single direction/plane parabolic configuration is preferred over a circular paraboloid to save costs, as it is easier to construct such a parabolic shape compared to one that is in more than one plane. This is because a circular paraboloid include no straight lines at all. In contrast, a single direction/plane parabolic configuration includes straight lines running in one direction. In the parabola used in the present invention, the straight lines run vertically, namely perpendicular to the ground  16 . However, it should be understood that the orientation of the parabola could be changed as desired by orienting the torsion box  20  in a different direction. 
         [0029]      FIG. 5  is a close-up view of the top fiberglass finished surface  21  that is carried by torsion box  20 . In  FIG. 5 , mirror strips  26 , preferably low iron-float glass, are adhered to the top fiberglass finished surface  21  by an adhesive, such as an epoxy. As can be seen in  FIGS. 1 ,  2  and  7 , these glass mirror strips  26  are preferably arranged in parallel and closely adjacent to one another across the width of the top surface  21  of the solar concentrator  10 . These mirrored glass strips  26  are standard mirror strips that are inexpensive and easy to install. Placing the strips  26  vertically across the width of the parabolic surface enables flat mirror strips  26  to be used thereby avoid custom mirror members that are curved or coating an entire surface that is curved with mirrored material. Thus, straight and flat mirror strips  26  are used in the present invention to simulate or approximate a curved parabolic mirror surface of that found in the prior art. 
         [0030]    Since an array of strips  26  are employed in the present invention, any given mirror strip  26  can be independently replaced for a localized repair obviating the need for a costly resurfacing of the mirror, which would be required in prior art solar concentrators that include a custom mirror surface.  FIG. 7  also illustrates that the overall dimensions of the solar concentrator  10 , namely the finished surface  21 , are preferably 10 feet in width and 8 feet in height. While these dimensions are preferred, the finished surface that can carry mirror strips  26  of the solar concentrator  10  of the present invention can be constructed of any size or shape. 
         [0031]    The torsion box  20  can best be seen in  FIGS. 5 ,  9 - 11 , where the rigid fiberglass structure provides a solid support for the fiberglass finish surface  21  as well as the support of the strips  26  of mirrored glass adhered thereon. The solar concentrator can both tilt relative to the ground and also rotate about an axis perpendicular to the ground. The two different directions of movement of the solar concentrator, namely two-axis tracking, can be seen by the representational figure of  FIG. 8 . 
         [0032]    Referring first to the tilting ability, the torsion box  20  includes gimbal mounting pins  22 , which are received by arms  18  of a support frame  14  that is, in turn, rotatably mounted to a base  12 , as seen in  FIGS. 5 ,  9 - 11 , which rotates about an axis that is perpendicular to the ground. More specifically, the two gimbal mounting pins  22  are respectively rotatably received in two mounting holes  24  in the base, as seen in  FIG. 1 . It is also possible to add sand bags to the base to help reduce vibration from wind, and the like. This enables the solar concentrator  10  to tilt about an axis that is parallel to the ground.  FIG. 9  shows the torsion box  20 , with mirror strips  26  thereon, in a very upright almost vertical position.  FIG. 10  shows the torsion box  20  tilted into an angled position while  FIG. 11  shows a substantially horizontal position of the torsion box  20  to enable the mirror strips  26  on the finish surface  21  to point directly upward to the sky.  FIGS. 9-11  illustrate the flexibility and range and tilting motion of the solar concentrator  10 . 
         [0033]    As described above, the torsion box  20  tilts relative the support frame  14 . For precision and automated control of such tilting action, an actuator or worm drive  34  is attached to the solar concentrator  10  to controllably tilt the solar concentrator about the gimbal mounting pins. For example, one end  34   a  of the actuator  34  is secured to the torsion box  20  and the opposing end  34   b  is secured to the support frame  14 . 
         [0034]    Similarly, for precision and automated control of the rotational action of the support frame  14  relative to the base  12 , as seen in  FIG. 13 , a motor  36  is attached to the base to enable horizontal rotation about an axis that is perpendicular to the ground. A light sensor or “sunseeker” may be employed to automate the tracking of the sun so that the solar concentrator  10  is always pointed in the optimal direction. For example, 180 degree rotation of the solar concentrator  10  can be achieved. The support frame  14  sits on top of ball bearings  38  so that it may freely rotated relative to the base  12 . The motor  36  is representationally shown to indicate that the movement of the support frame  14  relative to the base  12  is preferably motor assisted. 
         [0035]    The foregoing mechanisms for controlling tilting and rotational movement of the solar concentrator  10  are so well known in the art that they need not be discussed in further detail herein. 
         [0036]    In view of the foregoing, a new and novel improved solar concentrator is provided by the present invention that addresses the shortcomings of prior art solar concentrators. 
         [0037]    It would be appreciated by those skilled in the art that various changes and modifications can be made to the illustrated embodiments without departing from the spirit of the present invention. All such modifications and changes are intended to be covered by the appended claims.