Fresnel lens solar fluid heater

Abstract

A continuous-flow fluid heater using solar energy is presented, where the solar heating is accomplished by means of a Fresnel lens focused on a conduit through which fluid is conveyed at a rate sufficient to heat the fluid to a desired temperature. The Fresnel lens is pointed at the sun and the sun is tracked by means of an off-the-shelf clock drive or step-motor system. The fluids that can be heated include water and cooking oil, and with modifications to the system, other liquids including liquid metals.

1 - 4 . (canceled) 
     
     
         5 . A system for heating a fluid which comprises:
 a support frame;   a lens fixedly mounted on the support frame for concentrating solar radiation, and for directing the concentrated solar radiation onto a beam path;   a heat transfer conduit fixedly mounted on the support frame at a pre-determined distance from the lens, wherein the heat transfer element is positioned on the beam path for receiving concentrated solar radiation from the lens to heat the heat transfer element;   a motor assembly for moving the support frame, with the lens and heat transfer conduit thereon, to maintain a selected intensity of concentrated solar radiation incident on the heat transfer conduit; and   a means for pumping fluid through the heat transfer conduit to heat the fluid.   
     
     
         6 . A system as recited in  claim 5  wherein the heat transfer conduit comprises a body portion formed with a fluid passageway therethrough, and the system further comprises:
 a source of fluid to be heated;   a fluid transfer input connecting the source of fluid in fluid communication with the passageway of the heat transfer conduit for moving fluid from the fluid source and into the heat transfer conduit; and   a fluid transfer output connecting the heat transfer conduit in fluid communication with the source of fluid for moving fluid from the heat transfer conduit back to the fluid source.   
     
     
         7 . A system as recited in  claim 6  wherein the heat transfer conduit is formed with a plurality of fluid passageways. 
     
     
         8 . A system as recited in  claim 6  wherein the heat transfer conduit is made of a black metallic composite material. 
     
     
         9 . A system as recited in  claim 6  wherein the fluid is selected from a group consisting of water and cooking oil. 
     
     
         10 . A system as recited in  claim 5  wherein the motor assembly comprises:
 an altitude positioning motor connected with the support frame to establish an elevation angle for the beam path;   an azimuth positioning motor connected with the support frame to establish an azimuth angle for the beam path; and   a controller for coordinating operation of the altitude positioning motor with operation of the azimuth positioning motor to maintain a substantial alignment of the beam path with a direction from the system toward the sun.   
     
     
         11 . A system as recited in  claim 10  further comprising:
 a sensor mounted on the support frame, wherein the sensor generates a signal indicative of the intensity of solar radiation incident on the sensor; and   a means for electronically connecting the sensor to the controller for use by the controller in coordinating the respective operations of the altitude positioning motor and the azimuth positioning motor.   
     
     
         12 . A system as recited in  claim 5  wherein the lens is a Fresnel lens. 
     
     
         13 . A system as recited in  claim 5  further comprising:
 a means for selectively establishing the pre-determined distance on the support frame between the lens and the heat transfer conduit; and   a means for selectively replacing lenses on the support frame.   
     
     
         14 . A system for heating a fluid which comprises:
 a lens for concentrating solar energy, and for directing the concentrated solar energy along a beam path;   a heat transfer conduit positioned relative to the lens, at a fixed position on the beam path, to receive concentrated solar energy from the lens;   a means for moving the heat transfer conduit in concert with the lens to maintain a selected intensity of solar radiation incident on the heat transfer conduit; and   a means for pumping fluid through the heat transfer conduit to heat the fluid.   
     
     
         15 . A system as recited in  claim 14  further comprising a support frame with the heat transfer conduit mounted on the support frame, and with the lens mounted on the support frame at a pre-determined distance from the heat transfer conduit to establish the beam path. 
     
     
         16 . A system as recited in  claim 15  wherein the moving means comprises:
 an altitude positioning motor connected with the support frame to establish an elevation angle for the beam path;   an azimuth positioning motor connected with the support frame to establish an azimuth angle for the beam path; and   a controller for coordinating operation of the altitude positioning motor with operation of the azimuth positioning motor to maintain a substantial alignment of the beam path with a direction from the system toward the sun.   
     
     
         17 . A system as recited in  claim 16  further comprising:
 a sensor mounted on the support frame, wherein the sensor generates a signal indicative of the intensity of solar radiation incident on the sensor; and   a means for electronically connecting the sensor to the controller for use by the controller in coordinating the respective operations of the altitude positioning motor and the azimuth positioning motor.   
     
     
         18 . A system as recited in  claim 14  wherein the heat transfer conduit comprises a body portion formed with a fluid passageway therethrough, and the system further comprises:
 a source of fluid to be heated;   a fluid transfer input connecting the source of fluid in fluid communication with the passageway of the heat transfer conduit for moving fluid from the fluid source and into the heat transfer conduit; and   a fluid transfer output connecting the heat transfer conduit in fluid communication with the source of fluid for moving fluid from the heat transfer conduit back to the fluid source.   
     
     
         19 . A system as recited in  claim 14  wherein the lens is a Fresnel lens. 
     
     
         20 . A system as recited in  claim 14  wherein the heat transfer conduit is made of a black metallic composite material. 
     
     
         21 . A method for heating a fluid which comprises the steps of:
 mounting a lens and a heat transfer conduit on a support frame with a pre-determined, straight-line distance, measured from the lens to the heat transfer conduit, to establish a beam path between the lens and the heat transfer conduit;   directing solar energy, concentrated by the lens, along the beam path for incidence on the heat transfer conduit;   moving the support frame, with the lens and heat transfer conduit thereon, to maintain a selected intensity of concentrated solar radiation incident on the heat transfer conduit; and   pumping fluid through the heat transfer conduit to heat the fluid.   
     
     
         22 . A method as recited in  claim 21  further comprising the steps of:
 elevating the support frame to establish an elevation angle for the beam path;   turning the support frame to establish an azimuth angle for the beam path; and   coordinating the elevating step with the turning step to maintain a substantial alignment of the beam path with a direction from the system toward the sun.   
     
     
         23 . A method as recited in  claim 22  wherein the coordinating step is accomplished in response to the intensity of solar radiation incident on a sensor. 
     
     
         24 . A method as recited in  claim 23  further comprising the steps of:
 selectively replacing lenses on the support frame; and   selectively establishing the pre-determined distance between the lens and the heat transfer conduit.