Abstract:
A device for purifying water by solar power is described. The device has bottom and top sections, each being half-cylinders contacting one another along a flat edge to provide an elongated cylinder. The bottom section has an evacuated area with an optically transparent bottom surface that light can pass through to heat a liquid tray in the top section. A side-gutter directs water that condenses on an interior surface of the top section to an output port for collection.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to and is a non-provisional of U.S. Patent Application Ser. Nos. 62/091,888 (filed Dec. 15, 2014) and 62/186,779 (filed Jun. 30, 2015) the entirety of each of which is incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The subject matter disclosed herein relates to solar powered desalination devices. Governments in developing countries are challenged to provide sufficient amounts of potable drinking water to their population. In such countries water is often contaminated with salt or microorganisms which presents a health concern. While previous attempts have been made to provide potable water, none of these attempts have proven entirely satisfactory. These attempts often suffer from a lack of sufficient throughput or are too costly. Accordingly, alterative water purification devices are desired. 
         [0003]    The discussion above is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0004]    A device for purifying water by solar power is described. The device has bottom and top sections, each being half-cylinders contacting one another along a flat edge to provide an elongated cylinder. The bottom section has an evacuated area with an optically transparent bottom surface that light can pass through to heat a liquid tray in the top section. A side-gutter directs water that condenses on an interior surface of the top section to an output port for collection. 
         [0005]    In a first embodiment, a device for purifying water by solar power is provided. The device comprises a bottom section and a top section, each being half-cylinders contacting one another along a respective flat edge to provide an elongated cylinder; the bottom section comprising a cover that defines the flat edge of the bottom section that is sealed to an optically transparent bottom surface to provide an evacuated area that has a pressure of less than one atmosphere; and the top section comprises a liquid tray that defines the flat edge of the top section, at least one side-gutter that directs water that condenses on an interior surface of the top section to an output port, the liquid tray further comprising an input port for adding water into the liquid tray. 
         [0006]    In a second embodiment, a device for purifying water by solar power is provided. The device comprises a bottom section and a top section, each being half-cylinders contacting one another along a respective flat edge to provide an elongated cylinder; the bottom section comprising a cover that defines the flat edge of the bottom section that is sealed to an optically transparent bottom surface to provide an evacuated area that has a pressure of less than one atmosphere; and the top section comprises a liquid tray that defines the flat edge of the top section, the liquid tray being flanked by side-gutters that direct water that condenses on an interior surface of the top section to a front-gutter and through an output port, the side-gutters and the front-gutter at least partially circumscribing the liquid try, the liquid tray further comprising an input port for adding water into the liquid tray. 
         [0007]    In a third embodiment, a device for purifying water by solar power. The device comprises a bottom section and a top section, each being half-cylinders contacting one another along a respective flat edge to provide an elongated cylinder; the bottom section comprising a cover that defines the flat edge of the bottom section that is sealed to an optically transparent bottom surface to provide an evacuated area that has a pressure of less than one atmosphere; the top section comprises an optically transparent dome, a liquid tray that defines the flat edge of the top section, the liquid tray being flanked by side-gutters that direct water that condenses on an interior surface of the optically transparent dome to front-gutter and through an output port, the side-gutters and the front-gutter at least partially circumscribing the liquid try, the liquid tray further comprising an input port for adding water into the liquid tray; and an array of lenses disposed above the top section. 
         [0008]    This brief description of the invention is intended only to provide a brief overview of subject matter disclosed herein according to one or more illustrative embodiments, and does not serve as a guide to interpreting the claims or to define or limit the scope of the invention, which is defined only by the appended claims. This brief description is provided to introduce an illustrative selection of concepts in a simplified form that are further described below in the detailed description. This brief description is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. The claimed subject matter is not limited to implementations that solve any or all disadvantages noted in the background. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    So that the manner in which the features of the invention can be understood, a detailed description of the invention may be had by reference to certain embodiments, some of which are illustrated in the accompanying drawings. It is to be noted, however, that the drawings illustrate only certain embodiments of this invention and are therefore not to be considered limiting of its scope, for the scope of the invention encompasses other equally effective embodiments. The drawings are not necessarily to scale, emphasis generally being placed upon illustrating the features of certain embodiments of the invention. In the drawings, like numerals are used to indicate like parts throughout the various views. Thus, for further understanding of the invention, reference can be made to the following detailed description, read in connection with the drawings in which: 
           [0010]      FIG. 1  is a perspective view of a system for purifying water by solar power; 
           [0011]      FIG. 2A ,  FIG. 2B , and  FIG. 2C  are cross section views of a bottom section of the system; 
           [0012]      FIG. 3A  is a cross section of a top section of the system from the top while FIB.  3 B is a cross section of the top section from the side; 
           [0013]      FIG. 3C  is a cross section of the top section and bottom section being assembled; 
           [0014]      FIG. 3D  is a perspective view of side-gutters (shown in phantom) of the top section while  FIG. 3E  is a profile view of the side-gutters showing an angle of offset; 
           [0015]      FIG. 4A  is a cross section of the top section from the front showing relative placement of ports while  FIG. 4B  is a corresponding cross section from the back; 
           [0016]      FIG. 4C  is a cross section of the top section showing an absorbent material disposed within a liquid tray; 
           [0017]      FIG. 4D  is a cross section of the top section and the bottom section showing a horizontal tube in the bottom section and vertical tubes bridging between the top section and the bottom section; 
           [0018]      FIG. 5A ,  FIG. 5B  and  FIG. 5C  are cross sections of the system showing different modes of connection between the top section and the bottom section; 
           [0019]      FIG. 6  is a cross section of the system showing the use of a parabolic mirror; 
           [0020]      FIG. 7A  is a perspective view of the system showing the use of an array of lenses; 
           [0021]      FIG. 7B  is a top view of system showing the array of lenses while  FIG. 7C  is an end view of the array of lenses; 
           [0022]      FIG. 8A  is a cross section of the system showing the use of a lens between the parabolic mirror and the bottom section; 
           [0023]      FIG. 8B  is a cross section of another system showing the use of a lens between the parabolic mirror and the bottom section; and 
           [0024]      FIG. 9  is an end view of a system showing a frame with a motor for moving the parabolic mirror. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0025]    Disclosed in this specification is a solar powered linear desalination tube (LDT) that renders salt water potable for human consumption.  FIG. 1  depicts a linear dome solar water purifying device  100 . The water purifying device  100  is generally cylindrical and comprises a bottom section  200  and a top section  300 . A water reservoir  102  is provided that holds unpurified water. A water flow regulator  104  provides water from the water reservoir  102  to the water purifying device  100  through an input port  106  at a specific rate. The specific rate may be set, for example, by the rate at which the water purifying device  100  purifies water. Examples of suitable water flow regulators include float valves, drip house, spray mechanisms and soaker hoses. The water flow regulator functions to control the rate of water input to roughly correspond to the rate of purified water output. The water flow regulator  104  may be disposed inside of the water purifying device  100  (see  FIG. 3A ). After the water has been purified, potable water exits outlet port  108  and is collected in water collector  110  for subsequent use. The water purifying device  100  is shown in further detail in subsequent figures. 
         [0026]      FIG. 2A  depicts a cross section along line A-A′ of  FIG. 1  of the bottom section  200 . The bottom section  200  comprises an optically transparent surface  202  and a cover  204 . Suitable optically transparent materials include glass, acrylics (such as acrylics sold under the brand name PLEXIGLASS), polycarbonates (such as polycarbonates sold under the brand name LEXAN or MAKROLON) and other plastics. The cover  204  may be an optically transparent cover or an opaque, metallic cover that is thermally conductive.  FIG. 2A  and  FIG. 2B  differ in the mode of attachment of the cover  204 . In  FIG. 2A , the cover  204  is encompassed within the mouth of the optically transparent surface  202 . In  FIG. 2B , the cover  204  extends over the mouth of the optically transparent surface  202  to overhang a side of the optically transparent surface  202 . An airtight sealant may be used to main a vacuum within the bottom surface  202 . In another embodiment, the cover  204  of bottom section  200  and the bottom of top section  300  are monolithic and consist of aluminum or other metallic material that is sealed to the optically transparent bottom surface  202  to allow for evacuation of evacuated area  206 . The cover  204  forms an airtight seal with the optically transparent surface  202  so as to form an evacuated area  206 . The evacuated area  206  has been substantially evacuated of air such that the pressure within the evacuated area  206  is less than 0.8 atmosphere. In one embodiment, the pressure within the evacuated area  206  is less than 0.5 atmosphere. In another embodiment, the pressure within the evacuated area  206  is less than 0.1 atmosphere. Light  208  is transmitted through the optically transparent bottom surface  202  where it strikes the cover  204 . In one embodiment, a parabolic mirror (see parabolic mirror  600  of  FIG. 6 ) is used to direct the light  208 .  FIG. 2B  is an end view of the bottom section  200  along line B-B′ (see  FIG. 1 ) showing a solid proximate end. The distal end of the bottom section  200  also has such a solid end. 
         [0027]      FIG. 3A  provides a cross section along line C-C′ of  FIG. 1  of the top section  300 .  FIG. 3B  provides a cross section view of the top section  300  along line A-A′ of  FIG. 1 . In use, water is introduced through input port  302  where it accumulates in liquid tray  304 . The liquid tray  304  is a flat tray which may be a thermally conductive metal (e.g. aluminum) or an optically transparent material. In one embodiment, shown in  FIG. 3B , the liquid tray  304  forms the bottom of the top section  300 . In another embodiment, shown in  FIG. 3C , the liquid tray  304  is formed by the cover  204  of the bottom section  200  by sealing a joint  316  with a suitable watertight sealant. 
         [0028]    In use, the light  208  (see  FIG. 2A ) heats the cover  204  which, in turn, heats the water in liquid tray  304 . This causes a portion of the water to evaporate. The evaporated portion then condenses on an interior surface of a dome  308  ( FIG. 3B ) and accumulates in side-gutters  310 . In one embodiment, the dome  308  is optically transparent. The side-gutters  310  extend the length of the top section  300  and are in fluid communication with a front-gutter  312 . The side-gutters  310  and the front-cutter  312  extend perpendicular one another. In one embodiment, shown in  FIG. 3D  and  FIG. 3E , the side-gutters  310  are inclined by an angle θ relative to the liquid tray  304 .  FIG. 3D  is a phantom view of the side-gutters  310  and liquid tray  304  within the top section  300 .  FIG. 3E  is a schematic profile showing the relative orientation of the side-gutters  310  and the liquid tray  304 . The liquid tray  304  is roughly leveled such that water is generally contained. The angle θ guides water from the back of the side-gutters  310  toward the front-gutter  312 . The angle θ may be greater than 0° and less than 60°. In one embodiment, the angle θ is greater than 0° and less than 45°. In another embodiment, the angle θ is greater than 0° and less than 20°. The output port  314  removes the condensed water from the front-gutter  312  for subsequent use. Excess water may be removed from the liquid tray  304  through an overflow port  306 . In one embodiment, excess water is returned to the water reservoir  102 . 
         [0029]    As shown in  FIG. 4A  and  FIG. 4B , the input port  302  and the overflow port  306  are vertically staggered.  FIG. 4A  depicts the device  100  from viewpoint D of  FIG. 1 .  FIG. 4B  depicts the device  100  from viewpoint E of  FIG. 1 . The input port  302  is vertically disposed below the top of the side-gutter  310 . The overflow port  306  is above the input port  302  but at least partially below the top of the side-gutter  310  such that excess water in the side-cutter  310  will exit the overflow port  306  rather than introduce purified water back into the liquid tray  304 . 
         [0030]    In the embodiment of  FIG. 4C , an absorbent material  400 , such as an absorbent sponge, is provide that covers a bottom of the liquid tray  304 . The absorbent material increases the exposed surface area of water within liquid tray  304  and facilitates evaporation. In the embodiment of  FIG. 4C , the liquid tray  304  has a plurality of protrusions  402  extending from the bottom of the liquid tray  304  and increase the surface area of the bottom of the liquid tray  304 . These protrusions  402  function as radiators and transmit heat to the surrounding medium with the increased surface area (either directly to the water or indirectly to the water by way of the absorbent material  400 ). In one embodiment, the protrusions  403  are elongated ribs that extend the length of the liquid tray  304 . In another embodiment, the protrusions  403  are columns, such as spikes, that are arranged into rows. In one embodiment, shown in  FIG. 4D , the bottom of the liquid tray  304  has a plurality of vertical metal tubes  404  (such as vertical copper tubes) that connect with one or more horizontal metal tubes  406  (such as a horizontal copper tube) that are suspended in the evacuated section  206 . No water or other liquid need be contained within the horizontal metal tube  406 , but the horizontal metal tube  406  absorbs heat from being suspended within the evacuated section  206 . This heat transfers to the liquid tray  304  via the vertical metal tubes  404 . 
         [0031]      FIG. 5A ,  FIG. 5B  and  FIG. 5C  depict alternative embodiments where the bottom section  200  and the top section  300  are mated in different configurations. In  FIG. 5A , the bottom section  200  and the top section  300  are the same width. In  FIG. 5B , the top section  300  is wider than the bottom section  200  such that the liquid tray  304  is formed by the cover  204  while the side-gutters  310  overhang. In  FIG. 5C , the side-gutters  310  are also recessed by a distance  500  within the mouth of the optically transparent dome  308  to form a recessed lip. The bottom section  200  fits within the recessed lip to provide a sturdy connection. 
         [0032]    In one embodiment, a parabolic mirror is used to direct light toward the cover  204 .  FIG. 6  depicts the light  208  as it is directed by a parabolic mirror  600  and subsequently transmitted through the optically transparent bottom surface  202  to heat water in the liquid tray  304 . In another embodiment, the light  208  is directed by an array of concave lenses. One such embodiment is shown in  FIG. 7A . 
         [0033]      FIG. 7A  is a profile view that depicts an array  700  of lenses  702  disposed above the top section  300 . In the embodiment of  FIG. 7A  the top section  300  is optically transparent and the concave lenses  702  direct light into the top section  300  to facilitate evaporation.  FIG. 7A  provides a top view of the array  700 . The array comprises a central panel  704  that is flanked by two side-panels  706 ,  708 . As shown in  FIG. 7B  and  FIG. 7C , each panel expends parallel the longitudinal axis of the top section  300 . The central panel  704  extends parallel to the liquid tray  304  while the side-panels  706 ,  708  are offset from the plane of the central panel  704  by an angle  710  such that light is focused on the top section  300 . The magnitude of the angle  710  varies with the diameter of the top section  300  but generally is less than 180° and greater than 90°. In one embodiment, lenses  702  are Fresnel lenses, concave lenses, concave parabolic Fresnel lenses, linear Fresnel lenses or convex parabolic Fresnel lenses. 
         [0034]      FIG. 8A  depicts an embodiment that uses at least one lens between the parabolic mirror  600  and the bottom section  200 . In one such embodiment, an array of lenses is utilized similar to the array  700 . For simplicity of illustration, only a single lens is shown in the side view of  FIG. 8A . The lens  800  is a parabolic biconcave lens that has a focal length that directs light to a focal point  802 . The focal point  802  is spaced at a distance  804  from the bottom section  200 . 
         [0035]      FIG. 8B  depicts another embodiment that uses at least one lens between the parabolic mirror  600  and the bottom section  200 . In  FIG. 8B , a parabolic convex lens  806  is used that has a focal length that directs light to a focal point  808 . The lens  806  is placed such that the focal point  808  coincides with the lower surface of the bottom section  200 . 
         [0036]    As shown in  FIG. 9 , in one embodiment, the water purifying device  100  is supported on a frame  900  that allows rotation of the parabolic mirror  600  to track sunlight. The frame  900  provides a supporting scaffold that permits light to contact the device. In one embodiment, the frame  900  comprises at least one self-adjusting motor  902 . The self-adjusting motor  902  may be solar powered and is configured to re-position the parabolic mirror  600  to track the sun as the sun moves. 
         [0037]    This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.