Secondary reflector for linear fresnel reflector system

Abstract

A solar collection system having a secondary reflector is provided. The secondary reflector may be located above a field of primary reflectors and below a solar receiver. The secondary reflector may form a portion of an ellipse or macrofocal ellipse and be operable to reflect at least a portion of the solar radiation reflected by the primary reflectors onto the solar receiver. The secondary reflector may be disposed away from the solar receiver and associated tertiary reflectors such that it does not intercept reflected solar radiation from the outer primary reflectors that would otherwise have struck the solar receiver and tertiary reflectors had the secondary reflector not been present.

1 . A collector system comprising:
 at least two separately pivotable primary reflectors operable to reflect solar radiation;   at least one solar receiver operable to receive solar radiation, wherein the at least one solar receiver is positioned on a level above the at least two separately pivotable primary reflectors, wherein the collection aperture of the at least one solar receiver is downward facing; and   at least one secondary reflector operable to reflect at least a portion of a solar radiation reflected by the at least two separately pivotable primary reflectors onto at least a portion of the at least one solar receiver, wherein the at least one secondary reflector is positioned on a level below the at least one solar receiver, and wherein the secondary reflector comprises a first reflective surface.   
     
     
         2 . The collector system of  claim 1  further comprising at least one tertiary reflector associated with the at least one solar receiver, the at least one tertiary reflector operable to enlarge the collection aperture of the at least one solar receiver. 
     
     
         3 . The collector system of  claim 1 , wherein the first reflective surface forms at least a portion of an ellipse. 
     
     
         4 . The collector system of  claim 3 , wherein the ellipse is defined by foci located at an end of one of the at least one solar receiver and a top edge of one of the at least two separately pivotable primary reflectors at its highest position of use. 
     
     
         5 . The collector system of  claim 3 , wherein the ellipse is defined by foci located with a portion of the solar receiver and a portion of one of the at least two separately pivotable primary reflectors. 
     
     
         6 . The collector system of  claim 3  further comprising a tertiary reflector associated with the at least one solar receiver, the tertiary reflector operable to enlarge the collection aperture of the at least one solar receiver, wherein the ellipse is defined by foci located at a portion of the at least one solar receiver, a portion of the tertiary reflector, or a portion of one of the at least two separately pivotable primary reflectors. 
     
     
         7 . The collector system of  claim 1 , wherein the at least one secondary reflector further comprises a second reflective surface opposite the first reflective surface. 
     
     
         8 . The collector system of  claim 1 , wherein the at least one secondary reflector comprises two secondary reflectors. 
     
     
         9 . The collector system of  claim 8 , wherein a top portion of each secondary reflector of the at least one secondary reflector is separated by a space operable to allow heated air to pass through. 
     
     
         10 . The collector system of  claim 1  further comprising at least one light barrier operable to at least partially block the solar radiation reflected by the at least one the primary reflector. 
     
     
         11 . The collector system of  claim 10 , wherein the at least one secondary reflector further comprises a non-reflective surface opposite the first reflective surface. 
     
     
         12 . The collector system of  claim 10 , wherein the at least one secondary reflector further comprises a double-sided reflector. 
     
     
         13 . The collector system of  claim 10 , wherein the light barrier is a horizontal light barrier. 
     
     
         14 . The collector system of  claim 10 , wherein the light barrier is a vertical light barrier. 
     
     
         15 . The collector system of  claim 1 , wherein the at least two separately pivotable primary reflectors comprises at least two primary reflectors located on opposite sides of the at least one solar receiver. 
     
     
         16 . The collector system of  claim 1 , wherein the at least one solar receiver comprises at least one absorber tube for carrying a heat transfer fluid. 
     
     
         17 . The collector system of  claim 1 , wherein the at least two separately pivotable primary reflectors are flat reflectors. 
     
     
         18 . The collector system of  claim 1 , wherein the at least two separately pivotable primary reflectors are parabolic reflectors. 
     
     
         19 . The collector system of  claim 1 , wherein the first reflective surface forms at least a portion of macrofocal ellipse. 
     
     
         20 . A secondary reflector for use with a Linear Fresnel Reflector system, the secondary reflector comprising:
 a first reflective surface having a curvature defined by an ellipse, the reflective surface operable to reflect at least a portion of solar radiation reflected by a primary reflector directly onto a solar receiver while the secondary reflector is positioned on a level above the primary reflector and below the solar receiver.   
     
     
         21 . The secondary reflector of  claim 20 , wherein the ellipse is defined by foci located with a portion of the solar receiver and a portion of one of the at least one primary reflector. 
     
     
         22 . The secondary reflector of  claim 20  further comprising a second reflective surface opposite the first reflective surface. 
     
     
         23 . The secondary reflector of  claim 20  further comprising a light barrier configured to at least partially block a portion of the solar radiation directed towards a non-reflective surface opposite the first reflective surface. 
     
     
         24 . The secondary reflector of  claim 23 , wherein the light barrier is a horizontal light barrier. 
     
     
         25 . The secondary reflector of  claim 23 , wherein the light barrier is a vertical light barrier.