Solar Thermal System

Abstract

A solar thermal power system with associated heat exchanger, variable focus heliostat, and a heliostat stand with a pneumatic piston for shock absorption and positioning is disclosed. The heat exchanger is a solar receiver possessing a beveled bottom substantially perpendicular to the angles of the reflected light from the surrounding heliostats.

1 . A solar receiver comprising:
 a. a vessel for holding a heat transfer material, said vessel being configured as a substantially vertical cylindrical wall with a bottom edge and a top edge affixed to a base substantially configured as an inverted hollow frustum of a cone having an internal surface, an external surface, a base top connected to said bottom edge of said vertical cylindrical wall of said vessel, and a base bottom having a conduit port sealed about a inlet conduit segment and an outlet conduit segment to permit the entry and exit of a heat transfer fluid through a heat transfer fluid conduit;   b. a cap having a bottom face in a sealed arrangement with said top edge of said cylindrical wall; and   c. concentrically arranged compartments within said vessel separated by substantially annular compartment walls, said compartment walls extending from said bottom face of said cap to said internal surface of said base so as to seal each compartment, said compartments having heat transfer fluid conduits arranged as an annular ring in each compartment, and said annular rings connected so as to permit progressive flow from an outermost ring to an innermost ring through conduit ports in said compartment walls.   
     
     
         2 . The solar receiver of  claim 1 , wherein a reservoir contained within said cap is connected to said vessel by a valve which provides pressure relief for said vessel. 
     
     
         3 . The solar receiver of  claim 1 , wherein said annular rings are arranged in a vertically looping serpentine configuration within each said compartment. 
     
     
         4 . The solar receiver of  claim 1 , wherein said base is beveled above said port. 
     
     
         5 . The solar receiver of  claim 1 , wherein said base is bulbous above said port. 
     
     
         6 . The solar receiver of  claim 1 , wherein said vessel and said base are constructed of a copper alloy. 
     
     
         7 . The solar receiver of  claim 6 , wherein said heat transfer fluid conduit is constructed of a material selected from the group consisting of a copper alloy, stainless steel, and galvanized steel. 
     
     
         8 . The solar receiver of  claim 1 , wherein said heat transfer material is selected from the group consisting of carbon foam, cadmium, and zinc. 
     
     
         9 . The solar receiver of  claim 8 , wherein said heat transfer fluid is selected from the group consisting of water and molten salt. 
     
     
         10 . The solar receiver of  claim 9 , wherein said molten salt is a mixture of 60 percent sodium nitrate and 40 percent potassium nitrate. 
     
     
         11 . The solar receiver of  claim 10 , wherein said mixture contains calcium nitrate. 
     
     
         12 . The solar receiver of  claim 1 , wherein at least part of said internal surface of said base is covered by a layer of a wicking material that extends under at least part of said compartment walls from said conduit port to said cylinder wall. 
     
     
         13 . The solar receiver of  claim 1 , wherein said wicking material is a stainless steel felt. 
     
     
         14 . A heliostat drive comprising:
 a. a plurality of pneumatic pistons, wherein a first said piston engages a heliostat panel support about a horizontal axis and a second pneumatic piston engages a pneumatic piston support affixed to said first piston and arranged along a substantially vertical axis;   b. a heliostat panel support, said heliostat panel having a substantially planar heliostat support for engaging a heliostat panel, engaged with a drive mechanism which is driven by and engages a distal end of a pneumatic piston;   c. means to control said drive mechanism through the actuation of said plurality of pneumatic pistons; said means to control said drive mechanism controlling the flow of air to said plurality of pneumatic pistons so as to cause said pistons to move linearly along a pneumatic piston barrel and convert said linear movement of said piston into rotational movement of a drive mechanism by means of gears driven by a piston rod, said gears engaging a drive shaft at a distal end of each of said plurality of pneumatic pistons so as to provide linear to rotational translation of said linear motion of each said pneumatic piston; and   d. means for coupling said plurality of pneumatic pistons and said heliostat panel support.   
     
     
         15 . The heliostat drive of  claim 14 , wherein said drive is remotely controlled. 
     
     
         16 . The heliostat drive of  claim 14 , wherein said means to control said drive mechanism is a computer having machine readable instructions written in non-volatile memory to control said plurality of pneumatic pistons through the control of air flow to said plurality of pneumatic pistons. 
     
     
         17 . A solar thermal system comprising:
 a. a vessel for holding a heat transfer material, said vessel being configured as a substantially vertical cylindrical wall with a bottom edge and a top edge affixed to a base substantially configured as an inverted hollow frustum of a cone having an internal surface, an external surface, a base top connected to said bottom edge of said vertical cylindrical wall of said vessel, and a base bottom having a conduit port sealed about a inlet conduit segment and an outlet conduit segment to permit the entry and exit of a heat transfer fluid through a heat transfer fluid conduit;   b. a cap having a bottom face in a sealed arrangement with said top edge of said cylindrical wall;   c. concentrically arranged compartments within said vessel separated by substantially annular compartment walls, said compartment walls extending from said bottom face of said cap to said internal surface of said base so as to seal each compartment, said compartments having heat transfer fluid conduits arranged as an annular ring in each compartment, and said annular rings connected so as to permit progressive flow from an outermost ring to an innermost ring through conduit ports in said compartment walls;   d. a heliostat drive comprised of a plurality of pneumatic pistons, wherein a first said piston imparts rotation to a heliostat panel about a substantially horizontal axis and a second pneumatic piston imparts rotation to a heliostat panel about a substantially vertical axis; and   f. means to control said heliostat drive through the actuation of said plurality of pneumatic pistons; said means to control said drive mechanism controlling the flow of air to said plurality of pneumatic pistons so as to cause said pistons to move linearly along a pneumatic piston barrel and convert said linear movement of said piston into rotational movement of a drive mechanism by means of gears driven by a piston rod, said gears engaging a drive shaft at a distal end of each of said plurality of pneumatic pistons so as to provide linear to rotational translation of said linear motion of each said pneumatic piston.