Apparatus and methods for generating water in a fuel cell system

Abstract

Apparatus and methods for the generation of water in a direct oxidation fuel cell. Water, in addition to carbon dioxide and heat, is produced when carbonaceous fuel or fuel solution is oxidized in the presence of air and a suitable catalyst. This oxidation reaction is performed on a surface that allows for the introduction of oxygen in the presence of a catalyst. Water produced can then be directly added to the fuel solution thereby diluting the fuel solution to a desired concentration, or may be separately and then later added to fuel solution for the normal fuel cell operations depending on the permeability of the membrane to water.

1 . A water generator for a fuel cell system comprising: 
 a housing;    a substrate;    means for introducing oxygen into said housing;    means for introducing fuel or fuel solution into said housing;    means for reacting said fuel or fuel solution with said oxygen to produce carbon dioxide, water and heat;    means for mixing said water with said fuel to form dilute fuel; and    means for removing said water from said water generator.    
   
   
       2 . A water generating assembly, comprising: 
 a source of carbonaceous fuel;    a source of oxygen;    a catalyst;    means for introducing carbonaceous fuel from said source of carbonaceous fuel and means for introducing oxygen from said source of oxygen in the presence of said catalyst to oxidize the fuel, producing carbon dioxide, water and heat.    
   
   
       3 . The water generating assembly as defined in  claim 2  further comprising a control system for controlling the amount and introduction of at least one of fuel and oxygen to said catalyst.  
   
   
       4 . The water generating assembly as defined in  claim 2  wherein said catalyst is disposed on an element, which may include a substrate.  
   
   
       5 . The water generating assembly as defined in  claim 4  wherein said element is a substrate.  
   
   
       6 . The water generating assembly as defined in  claim 2  wherein said catalyst is disposed at one of the following: within a chamber, in a chamber, and on an aspect of a chamber.  
   
   
       7 . The water generating assembly as defined in  claim 2  used with an associated direct oxidation fuel cell wherein said catalyst is disposed within the anode chamber of said fuel cell.  
   
   
       8 . The water generating assembly as defined in  claim 2  used with an associated direct oxidation fuel cell wherein said catalyst is disposed within the cathode chamber of said fuel cell.  
   
   
       9 . The water generating assembly as defined in  claim 2  wherein said carbonaceous fuel includes methanol.  
   
   
       10 . The water generating assembly as defined in  claim 5 , wherein said substrate is a tubular substrate.  
   
   
       11 . The water generating assembly as defined in  claim 10  wherein said tubular substrate includes fluted walls.  
   
   
       12 . The water generating assembly as defined in  claim 10 , wherein said catalyst is disposed on an exterior aspect of said tubular substrate, and said tubular substrate is coupled with said source of fuel in such a manner that fuel is introduced into an interior aspect of said tubular substrate whereby some of said fuel passes from the interior aspect of said tubular substrate to said catalyst on the exterior aspect and the fuel reacts with oxygen, producing carbon dioxide, water and heat.  
   
   
       13 . The water generating assembly as defined in  claim 12 , wherein said catalyst is applied to at least a first portion of said tubular substrate and at least one second portion of the exterior aspect is exposed and is catalyst free such that water produced on said exterior aspect passes back into the interior aspect of said tubular substrate.  
   
   
       14 . The water generating assembly as defined in  claim 12 , wherein said exterior aspect of said tubular substrate is enclosed with a liquid-impermeable, gas-permeable material forming an enclosure defining a space between the exterior aspect and the enclosure as a water generation and collection area.  
   
   
       15 . The water generating assembly as defined in  claim 14 , wherein said enclosure provides either a pressure or a concentration gradient across the tubular substrate, and where carbon dioxide produced by oxidation of said fuel is released from the enclosure through the liquid-impermeable, gas-permeable material enclosing said tubular substrate.  
   
   
       16 . The water generating assembly as defined in  claim 10 , wherein said tubular substrate has said catalyst disposed on an interior aspect of said tubular substrate that is coupled with said source of fuel in such a manner that fuel and oxygen are introduced to the interior aspect of said tubular substrate whereby carbon dioxide, water and heat are produced on the interior aspect of said tubular substrate.  
   
   
       17 . The water generating assembly as defined in  claim 16  wherein said tubular substrate is comprised of a gas-permeable, liquid-impermeable material such that water, heat and carbon dioxide are generated at the interior aspect of said tubular substrate and carbon dioxide generated passes out through walls of said tubular substrate.  
   
   
       18 . The water generating assembly as defined in  claim 17 , wherein oxygen is introduced to the catalyst through said tubular substrate.  
   
   
       19 . The water generating assembly as defined in  claim 16 , wherein at least one portion of said tubular substrate is left uncatalyzed so that excess air and carbon dioxide may pass through to an exterior aspect of said tubular substrate resulting in liquid water being collected, substantially gas-free on an interior aspect of the gas-permeable, liquid-impermeable material.