Abstract:
A method of cooling a solar concentrator includes absorbing heat from solar energy collectors into a chamber section. The chamber section is arranged below, in a heat exchange relationship, the solar energy collectors.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is a continuation of U.S. Application Serial No. 12/686,675 filed Jan. 13, 2010, the disclosure of which is incorporated by reference herein in its entirety. 
     
    
     BACKGROUND 
       [0002]    The present invention relates to solar concentrators, and more specifically, to a multi-point cooling system for a solar concentrator. 
         [0003]    Solar power systems fall generally into two categories: fixed position flat panel systems, and tracking concentrator systems. Fixed position flat panel systems employ one or more stationary panels that are arranged in an area having an unobstructed view of the sun. As the earth rotates, the sun&#39;s rays move over the stationary panel(s) with varying degrees of intensity depending upon geographic location, time of day and time of the year. In contrast, solar concentrator systems collect, and focus the sun&#39;s rays onto one or more solar cells. Certain solar concentration systems employ tracking systems that follow the sun&#39;s path in order to enhance energy collection. Simply put, fixed position flat panel systems represent a passive solar collection system, while solar concentrator systems represent a more active energy collection system. 
         [0004]    Solar concentrator systems utilizing photovoltaic cells typically operate at or below about 500 suns concentration. Operating at higher sun concentration levels creates cooling challenges. At present, solar concentrator cooling systems are large unwieldy systems and/or possess limited cooling capacity. Thus, one major constraint that limits solar concentrator systems is the ability to adequately cool the photovoltaic cells. 
       SUMMARY 
       [0005]    According to an exemplary embodiment, a method of cooling a solar concentrator includes absorbing heat from solar energy collectors into a chamber section. The chamber section is arranged below, in a heat exchange relationship, the solar energy collectors. 
         [0006]    Additional features and advantages are realized through the techniques of the present invention. Other embodiments and aspects of the invention are described in detail herein and are considered a part of the claimed invention. For a better understanding of the invention with the advantages and the features, refer to the description and to the drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0007]    The subject matter which is regarded as the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The forgoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which: 
           [0008]      FIG. 1  is a schematic plan view of a solar concentrator including a multipoint cooling system in accordance with an exemplary embodiment; and 
           [0009]      FIG. 2  is a schematic plan view of a solar concentrator including a multipoint cooling system in accordance with another aspect of the exemplary embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0010]    With reference to  FIG. 1 , a solar concentrator constructed in accordance with an exemplary embodiment is indicated generally at  2 . Solar concentrator  2  includes an optical member or lens  4  having a plurality of focal points  6 - 8 . A plurality of solar energy collectors  10 - 12  are positioned at each of the respective focal points  6 - 8 . With this arrangement, incident solar radiation passing through optical member  4  is guided to focal points  6 - 8  and, by extension, onto solar energy collectors  10 - 12 . The solar energy collectors  10 - 12  convert the solar energy into electrical energy. As will be discussed more fully below, solar energy collectors  10 - 12  take the form of triple junction photovoltaic concentrator cells that operate at high solar concentrations, e.g., concentrations greater than 50 W/cm 2  (about 500 suns). In accordance with one aspect of the exemplary embodiment, solar energy collectors  10 - 12  can operate at concentration levels as high as 200 W/cm 2  (about 2000 suns) or more. As such, solar concentrator  2  requires a cooling system that will absorb and dissipate heat generated at solar energy collectors  10 - 12  operating at such concentration levels. At this point it should be understood that while only three solar energy collectors are shown, solar concentrator  2  could include many more solar energy collectors without departing from the scope of the claims. 
         [0011]    In accordance with an exemplary embodiment, solar energy collectors  10 - 12  are mounted to a multi-point cooling system  14 . More specifically, solar energy collectors  10 - 12  are mounted to a support member  16  formed from a metal or ceramic material having a high heat dissipation co-efficient. In accordance with one aspect of an exemplary embodiment, support member  16  is formed from one or more of Aluminum Nitride (AN), Aluminum Oxide (Al 2 O 3 ), Nickel and Copper. Solar energy collectors  10 - 12  are mounted to support member  16  via a corresponding plurality of thermal interface members  17 - 19 . In the exemplary embodiment shown, a layer of insulation is mounted to support member  16  about solar energy collectors  10 - 12 . Electrical connections  23 - 25  extend from respective ones of solar energy collectors  10 - 12  along insulation layer  20 . Electrical connections  23 - 25  lead to an energy storage device (not shown). 
         [0012]    In further accordance with the exemplary embodiment, multi-point cooling system  14  includes a base member  36 . Support member  16  is mounted to a base member  36  via a peripheral wall  40 . In a manner similar to that described above, base member  36  is formed from a metal or ceramic material having a high heat diffusion co-efficient. Base member  36  is spaced from support member  16  so as to define a chamber section  44 . In accordance with one aspect of the invention, chamber section  44  is filled with a vapor formed from, for example, water or ammonia, that enhances heat dissipation from solar energy collectors  10 - 12 . Base member  36  is also coupled to support member  16  via a plurality of structural supports  47 - 50 . Each structural support  47 - 50  is covered by a wicking material  52 - 55 . In accordance with one aspect of an exemplary embodiment, wicking material  52 - 55  is formed from sintered copper particles or from a material having machined grooves. Wicking material  52 - 55  enhances heat transferred from solar energy connectors  10 - 12  into chamber section  44 . In order to further enhance heat transfer, a plurality of nucleation membranes  59 - 61  is mounted to support member  16  within chamber section  44 . Each nucleation membrane  59 - 61  is positioned adjacent a corresponding one of solar energy collectors  10 - 12 . In accordance with an aspect of an exemplary embodiment, nucleation membranes  59 - 61  are formed from sintered copper particles arranged in a body formed from copper or aluminum. With this arrangement, vapor travels in wicking material  52 - 55  and or nucleation membranes  59 - 61 . Heat from the vapor is dissipated through, for example, base member  36  forming a condensate that returns to chamber section  44 . 
         [0013]    In order to facilitate heat energy transfer from chamber section  44 , solar concentrator  2  includes a plurality of cooling fins  66  mounted to base member  36 . Cooling fins  66  transfer heat energy from chamber section  44  to be dissipated via air currents passing across base member  36 . In accordance with one aspect of the invention, heat energy dissipation is further enhanced by a plurality of conduits  71 - 74  extending through chamber section  44 . Conduits  71 - 74  are configured and disposed to absorb heat energy from chamber section  44 . In accordance with one aspect of the invention of the present embodiment, conduits  71 - 74  include a non-circular cross-section and are filled with a liquid that is circulated within chamber section  44 . The liquid absorbs heat energy that is passed to, for example, a cooling medium after which the liquid is re-circulated back to chamber section  44 . 
         [0014]    Reference will now be made to  FIG. 2 , wherein like reference numbers represent corresponding parts in the respective use, in describing another aspect of the exemplary embodiment. In accordance with the embodiment shown, solar concentrator  2  includes a finned cold plate  86  mounted to base member  36 . More specifically, finned cold plate  86  includes a body  88  having a first substantially planar surface  90  and an opposing, second substantially planar surface  91 . First substantially planar surface  90  is provided with a plurality of cooling fins  95  that dissipate heat energy in a manner similar to that described above. Second substantially planar surface  91  is attached to base member  36  via a thermal interface member  98 . Thermal interface member  98  enhances energy transfer from base member  36  to finned cold plate  86 . In accordance with an aspect of an exemplary embodiment, finned cold plate  86  is formed from one of copper, aluminum or a high heat dissipation coefficient ceramic material. 
         [0015]    At this point, it should be understood that the exemplary embodiments provide a system for removing heat energy from a solar concentrator. That is, the present exemplary embodiments enable a solar concentrator to operate above 2000 suns while remaining cool. In contrast to existing systems that must operate substantially below 2000 suns, the exemplary embodiments provide sufficient cooling to enable the solar concentrator to operate at much higher solar concentration levels in order to enhance energy conversion. 
         [0016]    The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, element components, and/or groups thereof. 
         [0017]    While the preferred embodiment to the invention had been described, it will be understood that those skilled in the art, both now and in the future, may make various improvements and enhancements which fall within the scope of the claims which follow. These claims should be construed to maintain the proper protection for the invention first described.