Abstract:
An apparatus and method for generating hydrogen. The hydrogen generator includes a cylindrical body and two end plates defining a cavity therein. A plurality of elements are disposed within the cavity including an outer and inner gaskets, an outer and inner electrodes, and a proton exchange membrane. A bladder inflated within the cavity compresses the elements together and into firm contact with the inner wall of the body. A plurality of elongated bolts compresses the end plates against the ends of the cylindrical body. The hydrogen generator includes a water inlet port, an oxygen and water outlet port, and a hydrogen port extending. Connecting a DC voltage across the electrodes and pumping distilled water into the water inlet port produces hydrogen gas that can be used to fuel an internal combustion engine or a fuel cell.

Description:
FIELD OF THE INVENTION 
     This invention relates to generating hydrogen and specifically to an apparatus and method for generating hydrogen using a fuel cell. 
     BACKGROUND OF THE INVENTION 
     The production of hydrogen is important as there is now an emphasis to accelerate the establishment of a hydrogen economy to reduce the production of greenhouse gases. Hydrogen production on a small scale will be important for powering vehicles. A common method for small scale production of hydrogen is electrolysis. Electrolysis involves using an external voltage applied to an electrolytic cell to decompose water into hydrogen and hydroxide. The electrolytic cell typically includes an electrolyte and two electrodes. The electrolyte is usually a solution of water in which ions are dissolved. One problem with electrolytic cells is that the electrolyte is typically a corrosive liquid and care must be taken to contain the electrolyte and ensure that the electrolytic cell is safe to handle and operate. 
     A fuel cell offers a safer alternative to the use of electrolytic cells for the production of hydrogen. The fuel cell can be run in reverse to provide hydrogen fuel. Fuel cells are typically constructed as a fuel cell stacks that include a plurality of fuel cells stacked one upon the other and held in compression with respect to one another. The plurality of stacked fuel cells held in a compressive state form a fuel cell assembly. Each fuel cell includes a cathode layer, an anode layer, and an electrolyte disposed between the cathode layer and the anode layer. The fuel cell assembly requires a substantial amount of compressive force to hold the fuel cells of the assembly together. Prior art fuel cell stack structures typically use rigid end plates to impart and maintain a compressive force on the fuel cell assembly. Typically, ties rods extend through the end plates to impart a compressive force on the end plates and maintain the end plates in a spaced relationship. 
     Several problems arise as a result of maintaining a typical fuel cell assembly comprised of stacked fuel cells in a compressive relationship. As a result of the high compressive force that must be maintained on the fuel cell assembly, the rigid end plates have a tendency to deflect and not impart a uniform compressive force over the entire fuel cell assembly. The force applied over the central portion of the fuel cell assembly is typically not as great as the force applied to the periphery of the fuel cell assembly. Furthermore, the stacking of a plurality of fuel cells adds complexity to the overall design of the assembly and contributes to the difficulty of maintaining an even compressive force throughout the active area of each fuel cell within the stack. 
     What is needed therefore, is an apparatus and method for the production of hydrogen that reduces the complexity of the stacked fuel cell assembly and that applies a substantially uniform compressive force along the active area of the fuel cell assembly without requiring excessively thick end plates or the use of augmenting means for applying a uniform compressive force to the central portions of the fuel cells within the assembly. The apparatus for the safe production of hydrogen should be compact enough to be easily mounted singly or in a series configuration on a conventional vehicle with an internal combustion engine in order to provide an alternative fuel source for the vehicle and alternatively combined in any number of modules to provide commercial quantities for use in supplying hydrogen to power fuel cells. The apparatus for production of hydrogen could also be used in homes or businesses to supply hydrogen in place of natural gas. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to an apparatus and method for generating hydrogen. The hydrogen generator of the present invention includes a cylindrical sidewall or body and two end plates defining a cavity therein. A plurality of elements are disposed within the cavity including an outer gasket, an outer electrode, a proton exchange membrane, an inner electrode, and an inner gasket. A bladder is disposed within the body and inside the elements. A rubber gasket and an end plate are disposed at each end of the body and are held in a rigid spaced and compressed relationship with respect to the body. A water and oxygen port extends from the inner conductor layer through a first end plate. A hydrogen port extends through the body from the outer side of the proton exchange member. A water inlet port extends from a second end plate at one end of the fuel cell to inner side of the proton exchange membrane. A first terminal is connected to the outer conductor layer and a second terminal is connected to the inner conductor layer. An inflation tube extends from the bladder through the first end plate. 
     OBJECTS AND ADVANTAGES 
     Several advantages are achieved with the hydrogen generator apparatus and method of the present invention, including:
         (1) The hydrogen generator provides a simple and compact apparatus for producing hydrogen from water.   (2) The fuel cell based hydrogen generator of the present invention is inherently safer than prior art electrolyzers as it eliminates the use of corrosive electrolytes.   (3) The compact size of the hydrogen generator enables it to be easily mounted on a vehicle to provide hydrogen fuel source to power the vehicle.   (4) The hydrogen apparatus and method require only water and a voltage source to produce hydrogen fuel.   (5) Only modest input voltage is required to produce hydrogen with the hydrogen apparatus and method of the present invention.   (6) The voltage source can be supplied from either a battery or solar cells.   (7) The design of the hydrogen generator provides good contact between the proton exchange membrane and the electrodes.   (8) The hydrogen generator includes a cylindrical body and a central bladder that ensures even pressure and contact between the proton exchange membrane and the electrodes.       

     These and other objects and advantages of the present invention will be better understood by reading the following description along with reference to the drawings. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of the hydrogen generator of the present invention. 
         FIG. 2  is a schematic depicting a hydrogen generation system utilizing the hydrogen generator of the present invention. 
         FIG. 3  is a side view of the hydrogen generator of  FIG. 1 . 
         FIG. 4  is a top view of the hydrogen generator of  FIG. 3 . 
         FIG. 5  is a sectional view of the hydrogen generator taken along line  5 - 5  of  FIG. 3 . 
         FIG. 6  is a sectional view of the hydrogen generator taken along line  6 - 6  of  FIG. 4 . 
         FIG. 7  is a plan view of a rubber gasket that forms a portion of the hydrogen generator of  FIG. 6 . 
         FIG. 8  is a plan view of a mesh electrode layer that forms a portion of the hydrogen generator of  FIG. 6 . 
         FIG. 9  is a plan view of a proton exchange membrane that forms a portion of the hydrogen generator of  FIG. 6 . 
         FIG. 10  is a plan view of a top and bottom gasket that forms a portion of the hydrogen generator of  FIG. 6 . 
         FIG. 11  is a side view of the top and bottom gasket of  FIG. 10 . 
         FIG. 12  is a schematic depicting the sequence and arrangement of inserting internal components in constructing the hydrogen generator of the present invention. 
         FIG. 13  is an exploded perspective view of the hydrogen generator including the internal bladder and end plates exploded away from the cylindrical body. 
     
    
    
     
       
         
               
             
               
               
             
           
               
                   
               
               
                 22) INDEX TO REFERENCE NUMERALS IN DRAWINGS 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 20 
                 hydrogen generator, preferred embodiment 
               
               
                 22 
                 cylindrical sidewall or body 
               
               
                 24 
                 top end plate 
               
               
                 26 
                 bottom end plate 
               
               
                 28 
                 elongated bolt 
               
               
                 30 
                 water inlet port 
               
               
                 32 
                 hydrogen outlet tube 
               
               
                 34 
                 positive electrical terminal 
               
               
                 36 
                 negative electrical terminal 
               
               
                 38 
                 oxygen/water outlet port 
               
               
                 40 
                 inflator tube 
               
               
                 42 
                 outer gasket 
               
               
                 44 
                 outer electrode 
               
               
                 46 
                 proton exchange membrane 
               
               
                 48 
                 inner electrode 
               
               
                 50 
                 inner gasket 
               
               
                 52 
                 bladder 
               
               
                 54 
                 interior wall or inner wall of body 
               
               
                 56 
                 top edge of inner gasket 
               
               
                 58 
                 bottom edge of inner gasket 
               
               
                 60 
                 side edge of inner gasket 
               
               
                 62 
                 inner periphery 
               
               
                 63 
                 opening in inner gasket 
               
               
                 64 
                 top edge of electrode 
               
               
                 66 
                 bottom edge of electrode 
               
               
                 68 
                 side edge of electrode 
               
               
                 70 
                 top edge of membrane 
               
               
                 72 
                 bottom edge of membrane 
               
               
                 74 
                 side edge of membrane 
               
               
                 75 
                 end gasket 
               
               
                 76 
                 inner periphery of end gasket 
               
               
                 78 
                 outer edge of end gasket 
               
               
                 80 
                 opening in end gasket 
               
               
                 82 
                 cavity 
               
               
                 84 
                 aperture in sidewall 
               
               
                 86 
                 first bore in top end plate 
               
               
                 88 
                 second bore in top end plate 
               
               
                 89 
                 non-grooved portion of inner wall 
               
               
                 90 
                 groove in sidewall or body 
               
               
                 91 
                 power source 
               
               
                 92 
                 oxygen storage/water accumulator 
               
               
                 93 
                 water pump 
               
               
                 94 
                 hydrogen storage tank 
               
               
                 95 
                 vehicle 
               
               
                 96 
                 radiator 
               
               
                 97 
                 cooling water inlet 
               
               
                 98 
                 cooling water outlet 
               
               
                   
               
             
          
         
       
     
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference to  FIG. 1  there is shown a preferred embodiment of a hydrogen generator  20  that includes a rigid cylindrical body or sidewall  22  with a rigid top end plate  24  and a rigid bottom end plate  26  closing off the two ends of the sidewall  22 . Several elongated bolts  28  extend through the end plates  24 ,  26  and secure them tightly against the sidewall  22 . The hydrogen generator  20  includes a water inlet port  30  in the bottom end plate  26  and a hydrogen outlet tube  32  extending from the sidewall  22 . The hydrogen generator  20  includes a positive electrical terminal  34  extending through the top end plate  24  and a negative electrical terminal  36  extending through the sidewall  22 . The electrical terminals  34  and  36  are preferably constructed of stainless steel or titanium. The top end plate  24  additionally includes an oxygen/water outlet  38  and an inflator tube  40  extending there from. 
     With reference to  FIG. 5 , the interior of the hydrogen generator  20  includes several flexible layers arranged within the sidewall  22  including an outer gasket  42 , an outer electrode  44 , a proton exchange membrane  46 , an inner electrode  48 , and an inner gasket  50 . A bladder  52  is disposed within the sidewall  22  and, when inflated as shown in  FIG. 5 , exerts pressure against the various flexible layers and presses them into firm contact with one another and into firm engagement with the interior wall  54  of the cylindrical sidewall  22 . A bladder  52  such as described herein is available from automotive suppliers such as Air Lift Company of Lansing, Mich. 
     Referring to  FIG. 7 , the outer  42  and inner gaskets  50 , of which the outer gasket  42  is shown, are formed from a sheet of elastomeric material such as natural or synthetic rubber and are stamped or cut in the shape of a picture frame shape. The outer  42  and inner gaskets  50  include a top edge  56 , bottom edge  58 , side edges  60 , an inner periphery  62 , and an opening  63  therein. 
     As shown in  FIG. 8 , the outer electrode  44  and inner electrode  48 , of which the outer electrode  44  is shown, are cut or stamped from mesh or expanded metal sheet material in a rectangular shape and are preferably constructed of titanium mesh. Each electrode includes a top edge  64 , bottom edge  66 , and side edges  68 . The length and width of outer  44  and inner electrodes  48  are cut to a size to fit within the opening  63  of the outer  42  and inner  50  gaskets respectively and substantially fill the inner periphery  62  of the respective gasket. 
       FIG. 9  depicts the proton exchange membrane  46 , which is cut in a rectangular shape for use in the hydrogen generator of the present invention. The proton exchange membrane  46  is preferably a HYDRION® membrane available from Ion Power, Inc. of New Castle, Del. The HYDRION® membrane is constructed of NAFION®, a product available from DuPont of Wilmington, Del. and includes a coating of platinum and iridium catalysts. The proton exchange membrane includes a top edge  70 , bottom edge  72 , and side edges  74 . 
     With reference to  FIGS. 10 and 11 , there is shown an end gasket  75  that forms a portion of the hydrogen generator of the present invention. The end gasket  75 , two of which are used, are stamped or cut from a sheet of elastomeric material such as natural or synthetic rubber and are shaped in the form of an annulus as shown in  FIG. 10 . The end gasket  75  includes a circular inner periphery  76 , a circular outer edge  78 , and an opening  80  therein. Most preferably, the end gasket  75  is constructed of ethylene propylene di-monomer (EPDM) synthetic rubber. 
     Referring to  FIG. 12 , the preferred embodiment of the hydrogen generator  20  of the present invention is constructed by providing a bottom end plate  26 , an annulus-shaped end gasket  75 , and a sidewall  22  as shown. The end gasket  75  is inserted on the bottom end plate  26  and the sidewall  22  placed there on. For illustration of the sequence of constructing a hydrogen generator  20  according to the present invention, some of the various internal components are depicted in their original or unbiased shape. The outer gasket  42 , outer electrode  44 , proton exchange membrane  46 , inner electrode  48 , and inner gasket  50  are each rolled into a cylindrical shape and then inserted into the cavity  82  bounded by the sidewall  22  and end plate  26 . The sequence of insertion of the internal components includes inserting the outer gasket  42 , the outer electrode  44 , the proton exchange membrane  46 , the inner electrode  48 , and finally the inner gasket  50  into the cavity  82 . The outer electrode  44  fits within and substantially fills the opening  63  within outer gasket  42  and the inner electrode  48  fits within and substantially fills the opening  63  within inner gasket  50 . 
     With reference to  FIG. 13 , there is shown an exploded perspective view of the hydrogen generator  20  including the internal bladder  52  and end plates  24  and  26  exploded away from the sidewall  22 . Although the bottom end plate  26  and end gasket  75  are shown exploded away from the sidewall  22 , as described in the previous paragraph, the bottom end plate  26  and end gasket  75  are first placed in contact with the sidewall or body  22 . As the outer electrode  44  is placed in the cavity  82 , the negative electrical terminal  36  is inserted through aperture  84  in the sidewall  22  and secured to the outer electrode  44  by welding, soldering or other conventional means to establish good electrical contact between the negative electrical terminal  36  and the outer electrode  44 . In a similar manner, prior to inserting the inner electrode  48  into the cavity  82 , positive electrical terminal  34  is secured to the inner electrode  48 , by welding, soldering or other conventional means, to establish good electrical contact between positive electrical terminal  34  and the inner electrode  48 . After all of the components are inserted within the cavity  82  with their bottom edges in contact with the bottom end plate  26 , bladder  52  is inserted within the cavity  82 . A second end gasket  75  is then inserted over the top of the cylindrical body  22 . The top end plate  24 , which includes a first bore  86  and second bore  88  therein, is then placed over the top of the second end gasket  75  and cylindrical body  22  in such a manner that inflator tube  40  of bladder  52  and positive electrical terminal  34  extend through the first bore  86  and second bore  88  respectively. As shown in  FIG. 3 , elongated bolts  28  are then secured through both end plates  24  and  26  and tightened to compress both end gaskets  75  against the top and bottom ends of the cylindrical body  22  and seal the hydrogen generator. 
     Reference is made to  FIG. 6  for a description of the operation of the hydrogen generator of the present invention. For ease of explanation,  FIG. 6  depicts the hydrogen generator  20  without the elongated bolts  28 . In order to better illustrate the operation of the present invention, the various elements within the hydrogen generator  20 , including the outer gasket  42 , outer electrode  44 , proton exchange membrane  46 , inner electrode  48 , inner gasket  50 , and bladder  52  are depicted substantially thicker than actual. After all the internal components are inserted into the cavity  82  and the end plates  24  and  26  are secured, air, nitrogen, or a non-compressible fluid is introduced through inflator tube  40  to pressurize the bladder  52 . The bladder  52  is pressurized until it has exerted pressure against all the surrounding components and the components are pressed tightly together and held securely against the inner wall  54  of the cylindrical body  22 . Preferably, the bladder  52  is pressurized to between 50 and 100 psi. The function of the outer gasket  42  and inner gasket are to seal around the periphery of the top edges, bottom edges, and side edges of the proton exchange member  46 . Thus distilled water introduced at water inlet port  30  flows around the outer surface of the bladder  52  and upward through the inner mesh electrode  48 . As the distilled water flows upward in contact with the inner electrode  48 , the applied voltage to electrical terminal  34  creates a positive charge on the inner side of the proton exchange membrane  46  while electrical terminal  36  creates a negative charge on the outer side of the proton exchange membrane  46 . At the inner electrode or anode  48 , the platinum and iridium catalyst on the proton exchange membrane  46  causes the H 2 O molecules to split into positive hydrogen ions (H + ), and negatively charged electrons. The proton exchange membrane  46  allows only the positively charged hydrogen ions to pass through it to the outer electrode or cathode  44 . At the cathode the hydrogen ions combine with electrons to form hydrogen gas. Thus, in operation distilled water enters the hydrogen generator at the water inlet port  30 , oxygen and water exit at the oxygen/water outlet port  38  and hydrogen exits through hydrogen outlet tube  32 . As shown in  FIG. 6 , grooves  90  are provided around a substantial portion of the inner periphery of the cylindrical sidewall  22  in close proximity to the hydrogen outlet tube  32  to provide space for accumulating hydrogen gas and channeling it toward the hydrogen outlet tube  32 . Preferably, the grooves  90  are at least 0.031 inch in depth. As shown in  FIG. 5 , a portion  89  of the inner wall  54  is left non-grooved to provide a smooth surface for the outer gasket  42  and inner gasket  50  to create a surface for sealing around the side edges  74  of the proton exchange membrane  26 . The side edges  74  of the proton exchange membrane  26  are aligned with the non-grooved portion  89  of the inner wall  54 . 
     With reference to  FIG. 2  there is shown a schematic depicting a hydrogen generation system utilizing the hydrogen generator of the present invention. In the hydrogen generator  20 , distilled water is fed into water inlet port  30  and a power source  91  is connected to electrical terminals  34  and  36 . The power source  91  is preferably DC voltage and can be provided by a battery or solar panel (not shown). The voltage applied to the electrical terminals  34  and  36  is preferably between 1.5 and 2.0 volts. A voltage in this range enables the proton exchange membrane to operate at a high efficiency and produce approximately 7.5 liters per minute of hydrogen from a proton exchange membrane with an area of 80 square inches. Distilled water is stored in an oxygen storage/water accumulator tank  92  and a pump  93  propels the distilled water to the generator  20 . Inside the hydrogen generator  20  electricity and water are combined to create oxygen and hydrogen. Hydrogen exits the generator  20  through hydrogen outlet tube  32  and oxygen and water exit through the oxygen/water outlet port  38 . The hydrogen can be accumulated in a hydrogen storage tank  94  or be sent to the fuel feed of an internal combustion engine in a vehicle  95  as shown. The oxygen and water exit the hydrogen generator  20  at oxygen/water outlet port  38  and are cooled in a radiator  96  that includes a cooling water inlet  97  and cooling water outlet  98 . 
     With reference to  FIG. 6 , in the preferred embodiment of the hydrogen generator the sidewall or body  22  is preferably constructed of plastic or metal. Suitable plastics for constructing the body  22  include polypropylene, polyethylene, polyvinyl chloride (PVC), acrylonitrile-butadiene styrene (ABS), and polycarbonate. Suitable metals include aluminum and stainless steel. Most preferably the body  22  is formed of clear polyvinyl chloride. The end plates  24  and  26  are preferably constructed of a material that is an electrical insulator. More preferably the end plates  24  and  26  are constructed of plastic. Suitable plastics include polypropylene, polyethylene, polyvinyl chloride (PVC), acrylonitrile-butadiene styrene (ABS), and polycarbonate. Most preferably the end plates  24  and  26  are constructed of polycarbonate. As one example of a preferred embodiment, the cylindrical body  22  is formed from a 10-inch long piece of 4-inch Schedule 80 PVC pipe. 
     Most preferably the outer electrode  44  and inner electrode  48  are constructed of titanium mesh. The positive electrical terminal  34  and negative electrical terminal  36  are preferably constructed of titanium or stainless steel. Most preferably, the outer gasket  42  and inner gasket  50  are constructed of ethylene propylene di-monomer (EPDM) rubber. 
     Although the description above contains many specific descriptions, materials, and dimensions, these should not be construed as limiting the scope of the invention but as merely providing illustrations of some of the presently preferred embodiments of this invention. Thus the scope of the invention should be determined by the appended claims and their legal equivalents, rather than by the examples given.