Solar thermal receivers with multi-scale light trapping geometry and features

Abstract

Solar receivers including a plurality of multi-scale solar absorbing surfaces arranged such that light or heat reflected from or emitted from one or more of the plurality of solar absorbing surfaces impinges one or more other solar absorbing surfaces of the solar receiver. The disclosed receivers increase the amount of absorbed energy from a concentrated light source, such as a heliostat field, and reduce radiative and convective heat losses.

We claim: 
     
         1 . A solar receiver, comprising:
 a flat support panel; and   a plurality of solar panels attached to and extending from the support panel, the plurality of solar panels comprising a leading edge distant from the flat support panel and an opposing trailing edge proximate the flat support panel;   wherein the plurality of solar panels is attached to the flat support panel in a vertically stacked configuration such that the trailing edges are attached to the flat support panel in parallel; and   wherein one or more of the plurality of solar panels is arranged to reflect or radiate solar energy to one or more other solar panel of the plurality of solar panels to trap the reflected or radiated solar energy.   
     
     
         2 . The solar receiver of  claim 1 , wherein at least one solar receiver panel of the plurality of solar receiver panels are pivotally attached to the support panel. 
     
     
         3 . The solar receiver of  claim 1 , wherein the solar receiver is at least 85% efficient. 
     
     
         4 . The solar receiver of  claim 1 , wherein the plurality of solar panels contains a heat transfer fluid during operation, wherein the heat transfer fluid is introduced at a first temperature at the leading edge and is removed at a second temperature greater than the first temperature at the trailing edge during operation. 
     
     
         5 . The solar receiver of  claim 1 , wherein one or more of the plurality of solar panels comprises a plurality of tubes. 
     
     
         6 . The solar receiver of  claim 5 , wherein the plurality of tubes comprises leading surfaces offset between 0 and 45 degrees from an adjacent tube. The solar receiver of  claim 5 , wherein the plurality of tubes has a circular cross section that is offset by 30 degrees. 
     
     
         8 . The solar receiver of  claim 5 , wherein the plurality of tubes has a diamond cross section that is offset by 0 degrees. 
     
     
         9 . The solar receiver of  claim 5 , wherein the plurality of tubes has a cross-section selected from a group consisting of circular, rectangular, square and diamond.