Joints and Joining Methods for the Heat Transfer Fluid Circuit of Trough-Type Solar Collector Systems

Abstract

Embodiments disclosed herein include flexible joints configured to be positioned between the movable and stationary elements of a CSP heat transfer fluid circuit. Other embodiments include parabolic trough solar reflector modules, solar collectors or solar collector loops having joints between the movable and stationary elements of the heat transfer fluid circuit including at least one or more flexible pipes comprising a loop segment defining at least a partial loop around the axis of rotation.

What is claimed is: 
     
         1 . A solar collector comprising:
 a linear array of one or more parabolic trough reflectors wherein each parabolic trough reflector in the linear array is configured to reflect sunlight to a receiver positioned in an elongated zone of concentrated solar flux defined by the parabolic trough reflector;   one or more support frames with at least one support frame supporting each parabolic trough reflector in the linear array and providing for the supported parabolic trough reflector to be rotated around an axis of rotation parallel to the elongated zone of concentrated solar flux; and   a heat transfer fluid circuit comprising;
 a stationary supply pipe; 
 a first flexible pipe connecting the stationary supply pipe to the inlet of a first receiver associated with the first parabolic trough reflector in the linear array; 
 one or more crossover pipes connecting the outlets of the receivers of the parabolic trough reflectors in the linear array to the inlets of the receivers of adjacent parabolic trough reflectors; and 
 a second flexible pipe connecting the outlet of a last receiver associated with the last parabolic trough reflector in the linear array to a stationary return side pipe, wherein the first flexible pipe provides for heat transfer fluid to flow from the stationary supply pipe to the first receiver and the second flexible pipe provides for heat transfer fluid to flow from the last receiver to the stationary return pipe, and wherein the first and second flexible pipes comprise a loop segment defining at least a partial loop around the axis of rotation. 
   
     
     
         2 . The solar collector of  claim 1  wherein the loop segment defines a loop of at least 360°. 
     
     
         3 . The solar collector of  claim 1  wherein the loop segment of the first and second flexible pipes is supported at least in part by a drum. 
     
     
         4 . The solar collector of  claim 3  wherein the drum is centered upon the axis of rotation. 
     
     
         5 . The solar collector of  claim 1  wherein the stationary supply pipe, first flexible pipe, each receiver, each crossover pipe, the second flexible pipe and the stationary return pipe are electrically conductive and electrical conductivity is maintained throughout the heat transfer circuit. 
     
     
         6 . The solar collector of  claim 5  further comprising at least one transformer in electrical communication with the heat transfer fluid circuit and providing for electrical current flow within the heat transfer fluid circuit sufficient to cause impedance heating of the stationary supply pipe, first flexible pipe, each receiver, each crossover pipe, the second flexible pipe and the stationary return pipe. 
     
     
         7 . The solar collector of  claim 6  comprising two or more parabolic trough reflectors in the linear array and wherein no more than one transformer is associated with the heat transfer fluid circuit. 
     
     
         8 . The solar collector of  claim 1  wherein the first and second flexible pipes comprise a corrugated hose with a stainless steel overbraid. 
     
     
         9 . The solar collector of  claim 1  wherein the first and second flexible pipes comprise a coiled stainless steel pipe segment. 
     
     
         10 . The solar collector of  claim 1  further comprising a molten salt heat transfer fluid having a freezing temperature greater than 0° C. 
     
     
         11 . A fluid tight joint providing for the connection of a stationary pipe to the receiver of a parabolic trough solar reflector comprising:
 a flexible pipe;   a stationary pipe connection at a first end of the flexible pipe; and   a receiver connection at a second end of the flexible pipe wherein the flexible pipe comprises a loop segment defining at least a partial loop between the stationary pipe connection and the receiver connection.   
     
     
         12 . The fluid tight joint of  claim 11  wherein the loop segment defines a loop of at least 360°. 
     
     
         13 . The fluid tight joint of  claim 11  further comprising a drum supporting at least a portion of the loop segment. 
     
     
         14 . The fluid tight joint of  claim 11  wherein the flexible pipe is electrically conductive and electrical conductivity is maintained from the stationary pipe connection and the receiver connection. 
     
     
         15 . The fluid tight joint of  claim 11  wherein the flexible pipe comprises a corrugated inner hose and a stainless steel overbraid. 
     
     
         16 . The fluid tight joint of  claim 11  wherein the flexible pipe comprises a coiled stainless steel pipe segment. 
     
     
         17 . A method of joining a solar collector to stationary piping comprising:
 providing a linear array of one or more parabolic trough reflectors wherein each parabolic trough reflector in the linear array is configured to reflect sunlight to a receiver positioned in an elongated zone of concentrated solar flux defined by the parabolic trough reflector;   providing one or more support frames with at least one support frame supporting each parabolic trough reflector in the linear array and providing for the supported parabolic trough reflector to be rotated around an axis of rotation parallel to the elongated zone of concentrated solar flux;   providing a heat transfer fluid circuit comprising;
 a stationary supply pipe; 
 a first flexible pipe connecting the stationary supply pipe to the inlet of a first receiver associated with the first parabolic trough reflector in the linear array; 
 one or more crossover pipes connecting the outlets of the receivers of the parabolic trough reflectors in the linear array to the inlets of the receivers of adjacent parabolic trough reflectors; and 
 a second flexible pipe connecting the outlet of a last receiver associated with the last parabolic trough reflector in the linear array to a stationary return side pipe, wherein the first and second flexible pipes comprise a loop segment defining at least a partial loop around the axis of rotation; and 
 flowing heat transfer fluid from the stationary supply pipe to the first receiver, and flowing heat transfer fluid from the last receiver to the stationary return pipe, while the receivers are rotated in an arc around the axis of rotation. 
   
     
     
         18 . The method of  claim 17  wherein the loop segment defines a loop of at least 360°. 
     
     
         19 . The method of  claim 17  further comprising supporting the loop segment of the first and second flexible pipes at least in part with a drum. 
     
     
         20 . The method of  claim 19  wherein the drum is centered upon the axis of rotation. 
     
     
         21 . The method of  claim 17  wherein the stationary supply pipe, first flexible pipe, each receiver, each crossover pipe, the second flexible pipe and the stationary return pipe are electrically conductive and the method further comprises maintaining electrical conductivity throughout the heat transfer circuit. 
     
     
         22 . The method of  claim 21  further comprising providing at least one transformer in electrical communication with the heat transfer fluid circuit and providing for electrical current flow within the heat transfer fluid circuit sufficient to cause impedance heating of the stationary supply pipe, first flexible pipe, each receiver, each crossover pipe, the second flexible pipe and the stationary return pipe. 
     
     
         23 . The method of  claim 22  further comprising providing two or more parabolic trough reflectors in the linear array and providing no more than one transformer in electrical communication with the heat transfer fluid circuit 
     
     
         24 . The method of  claim 17  further comprising providing first and second flexible pipes comprising a corrugated hose with a stainless steel overbraid. 
     
     
         25 . The method of  claim 17  further comprising providing first and second flexible pipes comprising a coiled stainless steel pipe segment. 
     
     
         26 . The method of  claim 17  further comprising providing a molten salt heat transfer fluid having a freezing temperature greater than 0° C.