Multi-tube solar thermal receiver

Abstract

Systems, methods, and apparatus by which solar energy may be collected as heat are disclosed. Some systems include an elevated solar receiver comprising multiple tubes arranged lengthwise in the receiver in a side-by-side parallel configuration across a transverse dimension of the receiver. The receiver comprises an inlet section configured to receive a heat transfer fluid into the tubing arrangement and an outlet section configured to output heated heat transfer fluid from the tubing arrangement. The multiple tubes of the tubing arrangement define together a flowing circuit between the inlet section and the outlet section from the outer tube or tubes to the inner tube or tubes. The solar energy collector system further includes an instrumentation and control system for controlling the orientation of at least one orientable reflector to provide in operation a concentrated illuminated area comprising a peaked profile across the transverse dimension of the receiver.

1 . A solar energy collector system comprising:
 an elevated solar receiver comprising a tubing arrangement comprising multiple tubes arranged lengthwise in the receiver in a side-by-side parallel configuration across a transverse dimension of the receiver, the multiple tubes comprising an inner tube or tubes, a first outer tube or tubes on one side of the inner tube or tubes, and a second outer tube or tubes on an opposite side of the inner tube or tubes from the first outer tube or tubes;   at least one orientable reflector operable to direct incident solar radiation to form a concentrated illuminated area on the tubing arrangement; and   an instrumentation and control system for controlling the orientation of the at least one orientable reflector to provide in operation a concentrated illuminated area comprising a peaked profile across the transverse dimension of the receiver, wherein:
 the receiver comprises an inlet section configured to receive a heat transfer fluid into the tubing arrangement and an outlet section configured to output heated heat transfer fluid from the tubing arrangement; and 
 the multiple tubes of the tubing arrangement defining together a flowing circuit between the inlet section and the outlet section from the first and second outer tube or tubes to the inner tube or tubes. 
   
     
     
         2 . The solar energy collector system of  claim 1 , wherein the tubing arrangement is configured such that the concentrated illuminated area distributes heat flux to the heat transfer fluid within the tubing arrangement such that, in operation, the density of the fluid within a tube of the tubing arrangement is inversely related to the heat flux delivered to that tube. 
     
     
         3 . The solar energy collector system of  claim 1 , configured as a linear Fresnel solar energy collector system, wherein:
 the receiver is an elevated linear receiver;   the at least one orientable reflector is contained within a reflector row that is aligned parallel to the receiver and focuses incident radiation on the receiver; and   the concentrated illuminated area comprises a line focus.   
     
     
         4 . The solar energy collector system of  claim 1 , wherein the tubing arrangement is symmetrical with respect to a longitudinal center line of the receiver. 
     
     
         5 . The solar energy collector system according to  claim 1 , further comprising a flow control device on the flowing circuit to control mass flow of heat transfer fluid into the tubing arrangement. 
     
     
         6 . The solar energy collector system according to  claim 1 , wherein the tubing arrangement comprises one or more thermal expansion sections that accommodates thermal expansion of the tubing arrangement. 
     
     
         7 . The solar energy collector system of  claim 6 , wherein at least one thermal expansion section extends in a plane defined by the multiple parallel tubes. 
     
     
         8 . The solar energy collector system of  claim 6 , wherein at least one thermal expansion section extends out of a plane defined by the multiple parallel tubes. 
     
     
         9 . The solar energy collector system of  claim 6 , wherein the thermal expansion section comprises a suspension mechanism having at least one clamp holding one of the tubes of the tubing arrangement, the suspension mechanism coupled to sliding or rolling means, said sliding or rolling means being supported by a track interconnected with the receiver structure and defining a path parallel to the tube length for said sliding or rolling means. 
     
     
         10 . The solar energy collector system of  claim 1 , wherein:
 the inlet section comprises a first inlet section;   the outlet section comprises a first outlet section;   the inner tube or tubes comprises a first inner tube;   heat transfer fluid enters the tubing arrangement through the first inlet section to enter the first outer tube or tubes to flow in a first direction to reach a turnaround header that redirects heat transfer fluid to enter the first inner tube to flow in a second flow direction counter-parallel to the first flow direction to reach the first outlet section; and   the concentrated illuminated area provides greater heat flux to the first inner tube than to the first outer tube or tubes.   
     
     
         11 . The solar energy collector system of  claim 10 , wherein:
 the inlet section further comprises a second inlet section;   the outlet section further comprises a second outlet section;   the inner tube or tubes further comprises a second inner tube; and   heat transfer fluid enters the tubing arrangement through the second inlet section to flow in the first flow direction in the second outer tube or tubes to reach a second turnaround header that redirects the heat transfer fluid to enter the second inner tube and flow in the second flow direction to reach the second outlet section.   
     
     
         12 . The solar energy collector system of  claim 10 , wherein:
 the inlet section further comprises a second inlet section; and   the heat transfer fluid enters the tubing arrangement through the second inlet section to flow in the first flow direction in the second outer tube or tubes to reach a second turnaround header that redirects heat transfer fluid to enter the first inner tube and flow in the second flow direction to reach the first outlet section.   
     
     
         13 . The solar energy collector system of  claim 10 , wherein the first inner tube has an inner diameter greater than that of the first outer tube or tubes. 
     
     
         14 . The solar energy collector system of  claim 10 , wherein the tubing arrangement comprises a plurality of tubes connected in parallel with the first outer tube or tubes, and wherein the tubing arrangement is configured such that heat transfer fluid flows in the first direction through the plurality of tubes to reach the turnaround header. 
     
     
         15 . The solar energy collector system of  claim 10 , wherein the tubing arrangement comprises a plurality of tubes connected in parallel with the first inner tube, and wherein the tubing arrangement is configured such that heat transfer fluid flows in the second direction through the plurality of tubes to reach the first outlet section. 
     
     
         16 . The solar energy collector system of  claim 10 , wherein the tubing arrangement comprises a serpentine path between the first outer tube or tubes and the first inner tube such that heat transfer fluid flow path intersects the concentrated illuminated area more than twice. 
     
     
         17 . A method of collecting solar energy, the method comprising:
 flowing a heat transfer fluid into a tubing arrangement of an elevated solar receiver through an inlet section, wherein the tubing arrangement comprises multiple tubes arranged lengthwise in the receiver in a side-by-side parallel configuration across a transverse dimension of the receiver, the multiple tubes comprising an inner tube or tubes, a first outer tube or tubes on one side of the inner tube or tubes, and a second outer tube or tubes on an opposite side of the inner tube or tubes from the first outer tube or tubes; and   concentrating solar radiation onto the elevated solar receiver to form a concentrated illuminated area comprising a peaked profile across a transverse dimension of the receiver, wherein:
 the receiver comprises an inlet section configured to receive the heat transfer fluid into the tubing arrangement and an outlet section configured to output heated heat transfer fluid from the tubing arrangement; and 
 the multiple tubes of the tubing arrangement defining together a flowing circuit between the inlet section and the outlet section from the outer tube or tubes to the inner tube or tubes. 
   
     
     
         18 . The method of  claim 17 , wherein the tubing arrangement is configured such that the concentrated illuminated area distributes heat flux to the heat transfer fluid within the tubing arrangement such that, in operation, the density of the fluid within a tube of the tubing arrangement is inversely related to the heat flux delivered to that tube. 
     
     
         19 . The method of  claim 17 , further comprising controlling mass flow of the heat transfer fluid into the tubing arrangement using a flow control device. 
     
     
         20 . The method of  claim 17 , wherein the tubing arrangement comprises one or more thermal expansion sections that accommodates thermal expansion of the tubing arrangement. 
     
     
         21 . The method of  claim 20 , wherein at least one thermal expansion section extends in a plane defined by the multiple parallel tubes. 
     
     
         22 . The method of  claim 20 , wherein at least one thermal expansion section extends out of a plane defined by the multiple parallel tubes. 
     
     
         23 . The method of  claim 20 , wherein the thermal expansion section comprises a suspension mechanism having at least one clamp holding one of the tubes of the tubing arrangement, the suspension mechanism coupled to sliding or rolling means, said sliding or rolling means being supported by a track interconnected with the receiver structure and defining a path parallel to the tube length for said sliding or rolling means. 
     
     
         24 . The method of  claim 17 , wherein:
 the inlet section comprises a first inlet section;   the outlet section comprises a first outlet section;   the inner tube or tubes comprises a first inner tube;   flowing the heat transfer fluid into the tubing arrangement comprises flowing the heat transfer fluid into the tubing arrangement through the first inlet section to enter the first outer tube or tubes to flow in a first direction to reach a turnaround header that redirects heat transfer fluid to enter the first inner tube to flow in a second flow direction counter-parallel to the first flow direction to reach the first outlet section; and   the concentrated illuminated area provides greater heat flux to the first inner tube than to the first outer tube or tubes.   
     
     
         25 . The method of  claim 24 , wherein the first inner tube has an inner diameter greater than that of the first outer tube or tubes.