Solar energy receiver having optically inclined aperture

Abstract

The present application provides a solar energy receiver comprising an effective absorption aperture that is biased, so that solar radiation from a certain direction can be preferentially absorbed by a solar radiation absorber in the receiver. The effective absorption aperture is inclined relative to a physical aperture. Thus, in an elevated receiver comprising a downward facing physical aperture defining a plane that is relatively parallel to ground, the effective absorption aperture of the receivers described herein may be inclined relative to ground, but the physical aperture may remain generally parallel to ground. The biased receivers may be used in Linear Fresnel Reflector solar arrays.

1 . A solar energy receiver comprising:
 a cavity having opposing side walls and a physical aperture defined between the side walls;   a solar radiation absorber disposed within the cavity and arranged to be illuminated by solar radiation directed through the physical aperture; and   a first reflector element located at least partly within the cavity and configured to reflect incident solar radiation toward the solar radiation absorber and so establish an effective absorption aperture that is inclined relative to a plane defined by the physical aperture.   
     
     
         2 . The solar energy receiver of  claim 1 , wherein the physical aperture is substantially parallel to ground. 
     
     
         3 . The solar energy receiver of  claim 1 , wherein the side walls are two opposing side walls that are part of an inverted trough that defines the cavity. 
     
     
         4 . The solar energy receiver of  claim 1 , wherein the solar radiation absorber comprises a plurality of solar radiation absorbing tubes arranged side-by-side in the cavity and extending longitudinally along the cavity, wherein the absorber tubes are configured to contain a heat transfer fluid. 
     
     
         5 . The solar energy receiver of  claim 1 , wherein the first reflector element comprises a reflective surface having a concave curvature facing toward the solar radiation absorber. 
     
     
         6 . The solar energy receiver of  claim 1 , further comprising a second reflector element located at least partly within the cavity and configured to reflect solar radiation toward the solar radiation absorber, wherein the second reflector element is arranged to be asymmetric in the receiver with respect to the first reflector element. 
     
     
         7 . The solar energy receiver of  claim 6 , wherein the second reflector element comprises a reflective surface having a concave curvature facing toward the solar radiation absorber. 
     
     
         8 . The solar energy receiver of  claim 5 , wherein the first reflector element comprises a reflective surface having an elliptical concave curvature facing toward the solar radiation absorber, and one focus of the reflective surface is at or near an edge of the absorber and the other focus is selected to be at or near an outer edge of a reflector field directing solar radiation to the receiver. 
     
     
         9 . The solar energy receiver of  claim 6 , wherein at least one of the first and second reflector elements comprises a reflective surface having an elliptical concave curvature facing toward the solar radiation absorber, and one focus of the reflective surface is at or near an edge of the absorber and the other focus is selected to be at or near an outer edge of a reflector field directing solar radiation to the receiver. 
     
     
         10 . The solar energy receiver of  claim 9 , wherein each of the first and second reflector elements comprise a reflective surface having an elliptical concave curvature facing toward the absorber and one focus of the reflective surface is at or near an edge of the absorber, and the other focus is selected to be at or near an outer edge of a reflector field directing solar radiation to the receiver. 
     
     
         11 . The solar energy receiver of  claim 6 , wherein the first and second reflector elements have different lengths extending from a base of the cavity outwardly toward the physical aperture. 
     
     
         12 . The solar energy receiver of  claim 6 , wherein the first and second reflector elements extend outwardly from a base of the trough at different angles so as to created an effective absorption aperture that is inclined relative to a plane defined by the physical aperture. 
     
     
         13 . The solar energy receiver of  claim 3 , wherein the first reflector element is slidably secured to the trough. 
     
     
         14 . The solar energy receiver of  claim 1 , wherein the first reflector element comprises a polished metal element. 
     
     
         15 . The solar energy receiver of  claim 1 , wherein the first reflector element comprises a silvered glass mirror. 
     
     
         16 . The solar energy receiver of  claim 1 , configured for use in a Linear Fresnel Reflector array. 
     
     
         17 . A solar energy collector system comprising:
 one or more reflector fields; and   an elevated receiver comprising a solar radiation absorber that is configured to receive and absorb solar radiation directed from the one or more reflector fields through a physical aperture of the receiver,   wherein the elevated receiver comprises an effective absorption aperture that is inclined relative to a plane defined by the physical aperture.   
     
     
         18 . The solar energy collector system of  claim 17 , wherein the physical aperture is substantially parallel to ground. 
     
     
         19 . The solar energy collector system of  claim 17 , wherein the one or more reflector fields are arranged asymmetric with respect to the elevated receiver, and the effective absorption aperture is inclined toward one side of the one or more reflector fields. 
     
     
         20 . The solar energy collector system of  claim 17 , wherein one or more reflector fields is oriented in a north-south direction. 
     
     
         21 . The solar energy collector system of  claim 17 , wherein one or more reflector fields is oriented in an east-west direction. 
     
     
         22 . The solar energy collector system of  claim 17 , wherein the one or more reflector fields are configured and the effective absorption aperture of the receiver is inclined so as to preferentially collect solar radiation directed thereto at a certain period during a diurnal cycle. 
     
     
         23 . The solar energy collector system of  claim 22 , configured so as to preferentially collect solar radiation directed thereto after noon. 
     
     
         24 . The solar energy collector system of  claim 17 , wherein the one or more reflector fields are configured and the effective absorption aperture is inclined so as to preferentially collect solar radiation directed thereto during a certain time of year. 
     
     
         25 . The solar energy collector system of  claim 17 , wherein the one or more reflector fields are configured and the effective absorption aperture of the receiver is inclined so as to increase annualized solar energy collection. 
     
     
         26 . A method for collecting solar radiation, the method comprising reflecting solar radiation from a reflector field through a physical aperture of an elevated receiver to be incident on a solar radiation absorber, wherein the receiver comprises an effective absorption aperture that is inclined relative to the physical aperture so as to preferentially receive and absorb radiation directed thereto from a designated side of the receiver. 
     
     
         27 . The method of  claim 26 , wherein the physical aperture is oriented substantially parallel to ground. 
     
     
         28 . The method of  claim 26 , wherein an amount of solar radiation reflected from a first side of the reflector field to the receiver is greater than an amount of solar radiation reflected from a second side of the receiver, and the effective absorption aperture is inclined toward the first side of the reflector field. 
     
     
         29 . The method of  claim 26 , comprising establishing the effective absorption aperture in the receiver by mounting a first reflector element at least partly within a cavity of the receiver, the cavity housing the absorber, wherein the first reflector element is configured to reflect incident solar radiation toward the absorber and so establish an effective absorption aperture that is inclined relative to ground. 
     
     
         30 . The method of  claim 26 , comprising establishing the effective absorption aperture in the receiver by mounting a second reflector element at least partly within the cavity, wherein the second reflector element is arranged to be asymmetric in the receiver with respect to the first reflector element, and the first and second reflector elements are configured to reflect incident solar radiation toward the absorber and so establish an effective absorption aperture that is inclined relative to ground. 
     
     
         31 . The method of  claim 26 , comprising configuring the reflector field and establishing the inclined effective absorption aperture for preferentially collecting solar radiation during a certain time of year. 
     
     
         32 . The method of  claim 26 , comprising configuring the reflector field and establishing the inclined effective absorption aperture for preferentially collecting solar radiation during a certain part of a diurnal cycle. 
     
     
         33 . The method of  claim 32 , comprising configuring the reflector field and establishing the inclined effective absorption aperture for preferentially collecting solar radiation during afternoon. 
     
     
         34 . A method for biasing solar radiation collection in a solar energy collector system, the method comprising:
 reflecting solar radiation from reflectors in one or more reflector fields to an elevated receiver; and   biasing the receiver to preferentially collect reflected solar radiation from a subset of the reflectors.   
     
     
         35 . The method of  claim 34 , comprising utilizing an elevated receiver having an optically inclined aperture to preferentially collect reflected solar radiation from a subset of the reflectors. 
     
     
         36 . The method of  claim 34 , comprising preferentially collecting reflected solar energy from reflectors located on an eastern side of the receiver to preferentially collect solar radiation during afternoon hours. 
     
     
         37 . The method of  claim 34 , comprising preferentially collecting reflected solar radiation from a subset of the reflectors to increase an annualized collection from the solar energy collector system. 
     
     
         38 . A solar energy receiver comprising:
 a cavity having opposing side walls and a physical aperture defined between the side walls;   a solar radiation absorber disposed within the cavity and arranged to be illuminated by solar radiation directed through the physical aperture; and   a first optical element located at least partly within the cavity or proximate to the cavity so as to establish an effective absorption aperture that is inclined relative to a plane defined by the physical aperture.   
     
     
         39 . The solar energy receiver of  claim 38 , wherein the first optical element diffracts incident solar radiation toward the absorber. 
     
     
         40 . The solar energy receiver of  claim 38 , wherein the first optical element refracts incident solar radiation toward the absorber. 
     
     
         41 . The solar energy receiver of  claim 38 , wherein the first optical element reflects incident solar radiation toward the absorber.