Polymer electrolyte fuel cell

Abstract

The polymer electrolyte fuel cell of the present invention is equipped with a cell having an MEA having a hydrogen ion-conducting polymer electrolyte membrane and an anode and a cathode sandwiching the polymer electrolyte membrane; a platelike anode-side separator positioned on one side of the MEA so that the front surface thereof contacts the anode, with fuel gas passages through which fuel gas flows being formed in the front surface; and a platelike cathode-side separator positioned on the other side of the MEA so that the front surface thereof contacts the cathode, with oxidizing gas passages through which oxidizing gas flows being formed in the front surface; a cell stack in which a plurality of said cells is stacked; and a cooling water flow passage, through which cooling water flows, formed on at least the rear surface of one from among the anode-side separator and the cathode-side separator of at least a prescribed cell in said cell stack; where said fuel gas, oxidizing gas, and cooling water flow through said fuel gas passage, oxidizing gas passage, and cooling water passage, respectively, in a manner not running counter to gravity.

1 . A polymer electrolyte fuel cell equipped with: 
 a cell comprising: 
 a membrane electrode assembly (MEA) comprising a hydrogen ion-conducting polymer electrolyte membrane and an anode and a cathode sandwiching the polymer electrolyte membrane;  
 a platelike anode-side separator positioned on one side of the MEA so that a front surface thereof contacts the anode, with fuel gas passages through which fuel gas flows being formed in the front surface; and  
 a platelike cathode-side separator positioned on the other side of the MEA so that a front surface thereof contacts the cathode, with oxidizing gas passages through which oxidizing gas flows being formed in the front surface;  
   a cell stack in which a plurality of said cells is stacked; and    a cooling water flow passage, through which cooling water flows, formed on at least the rear surface of one from among the anode-side separator and the cathode-side separator of at least a prescribed cell in said cell stack;    where said fuel gas, oxidizing gas, and cooling water flow through said fuel gas passage, oxidizing gas passage, and cooling water passage, respectively, in a manner not running counter to gravity.    
     
     
         2 . The polymer electrolyte fuel cell of  claim 1  wherein said fuel gas passage, oxidizing gas passage, and cooling water passage are each formed to run horizontally or with a downward gradient in the direction of flow.  
     
     
         3 . The polymer electrolyte fuel cell of  claim 2  wherein at least one from among said fuel gas passage, oxidizing gas passage, and cooling water passage is comprised of horizontal portions and vertical portions.  
     
     
         4 . The polymer electrolyte fuel cell of  claim 1  wherein the upstream portion of the oxidizing gas passage is positioned in the vicinity of the inlet of the cooling water passage in the cathode-side separator.  
     
     
         5 . The polymer electrolyte fuel cell of  claim 1  wherein the upstream portion of the fuel gas passage is positioned in the vicinity of the inlet of the cooling water passage in the anode-side separator.  
     
     
         6 . The polymer electrolyte fuel cell of  claim 1  wherein said cooling water passage and oxidizing gas passage are formed in said cathode-side separator so as to approximately align overall when viewed in the direction of thickness.  
     
     
         7 . The polymer electrolyte fuel cell of  claim 1  wherein, in said anode-side separator and said cathode-side separator, the inlet manifold hole supplying cooling water to the cooling water passage runs through said separators in the direction of thickness and is provided with a constriction comprised of locally narrowing portions in the opposing internal circumference surfaces, with a first portion positioned on one side of the constriction communicating to a cooling water supply pipe and a second portion positioned on the other side of the constriction communicating to the cooling water flow passage.  
     
     
         8 . The polymer electrolyte fuel cell of  claim 1  wherein, in said anode-side separator and said cathode-side separator, an inlet manifold hole supplying cooling water to the cooling water passages is provided so as to run through the separators in the direction of thickness and to have a step running in a circumferential direction on the lower portion of the inner circumference surface, with a first portion positioned beneath the step communicating to a cooling water supply pipe and a second portion positioned above the step communicating to the cooling water flow passage.  
     
     
         9 . A method of operating a fuel cell comprised of an MEA having a hydrogen ion-conducting polymer electrolyte membrane and an anode and cathode sandwiching the polymer electrolyte membrane comprising: 
 providing an anode-side separator positioned on one side of the MEA such that a front surface thereof contains the anode; providing fuel gas passages formed in the front surface;    providing a cathode-side separator positioned on one side of the MEA such that a front surface thereof contacts the cathode; providing oxidizing gas passages formed in the front surface;    feeding a moistened fuel gas through said fuel gas passages; feeding an oxidizing gas through said oxidizing gas passages;    reacting said fuel gas and oxidizing gas resulting in the release of heat; said released heat increasing the temperature of the fuel cell;    passing a cooling fluid comprising water through passages formed on at least the rear surface of one from among the anode-side separation and the cathode-side separation of said cell to absorb at least part of said released heat and hydrate the electrolyte membrane;    said flowing of said fuel gas and said oxidizing gas being in a direction not counter to gravity from an inlet to an outlet of said fuel gas and said oxidizing gas flow through said cell.    
     
     
         10 . The method according to  claim 9 , wherein said flowing comprises flowing said fuel gas in a direction either horizontal or in a downward gradient from an inlet to an outlet of said fuel gas.  
     
     
         11 . The method according to  claim 9  in which the flow of said oxidizing gas is in a direction either horizontal or in downward gradient from an inlet to an outlet of said oxidizing gas.  
     
     
         12 . The method of  claim 11  in which the flow of said oxidizing gas is also in a vertically downward direction.  
     
     
         13 . The method of  claim 9  in which the fuel gas flows from an inlet proximate a top of said fuel cell to an outlet proximate to a bottom of the fuel cell.  
     
     
         14 . The method of  claim 13 , wherein the cooling fluid flows from an inlet proximate the top of said fuel cell to an outlet proximate the bottom of the fuel cell.  
     
     
         15 . The method of  claim 13 , wherein the flow of cooling fluid is in a direction countercurrent with the flow of the fuel gas.  
     
     
         16 . The method of  claim 13 , wherein the inlet of the cooling fluid is proximate the inlet of the fuel gas.  
     
     
         17 . The method of  claim 9 , wherein the maintained fuel gas is moistened to less than 100 percent relative humidity.  
     
     
         18 . The method of  claim 9 , wherein condensation forms in at least one of the fuel gas passages and the cathode gas passages, said method further comprising flowing said condensation out of said fuel cell through passages which are at least one of horizontal and vertical descending; downwardly descending; downwardly descending and vertically descending; and horizontal, downwardly descending and vertically descending.  
     
     
         19 . The method of  claim 18 , wherein said condensation flows through passages which are essentially horizontal and vertically descending.  
     
     
         20 . The method of  claim 19 , wherein said condensation flows through at least two separate but parallel passages.  
     
     
         21 . The method of  claim 14 , wherein a constriction is present in a flow path of the cooling fluid at a position intermediate the cooling fluid passage and a cooling fluid supply manifold.  
     
     
         22 . The method of  claim 9 , in which the oxidizing gas flows from an inlet proximte a top of said fuel cell to an outlet proximate a bottom of the fuel cell.  
     
     
         23 . The method of  claim 22 , further comprising flowing the cooling fluid from an inlet proximate the inlet of said oxidizing gas to an outlet proximate a bottom of the fuel cell.  
     
     
         24 . The method of  claim 23 , wherein the flows of the oxidizing gas and the cooling fluid are countercurrent.  
     
     
         25 . The method of  claim 9 , further comprising providing a construction in an inlet for the cooling fluid passage and flowing the cooling fluid through said constriction.  
     
     
         26 . The method of  claim 25 , wherein the constriction is provided in the form of a flow passage interrupted by opposed protrusions.  
     
     
         27 . The method of  claim 25 , wherein the constriction is provided in the form of a step in a flow path of the cooling fluid.  
     
     
         28 . The method of  claim 9 , wherein the cooling fluid flow passage and the oxidizing gas flow passage are aligned throughout as viewed in the direction of thickness of the cathode-side separator.