Fuel cell stack

Abstract

A fuel cell stack is comprised of a plurality of power generating units which are stacked along the horizontal direction. A corrugated passage groove having a shape corresponding to the shape of the underside surface of a corrugated passage groove of a first fuel gas passage is formed in a surface of a first metal separator. A corrugated passage groove having a shape corresponding to the shape of the underside surface of a corrugated passage groove of a second oxidant gas passage is formed in a surface of a third metal separator. The corrugated passage grooves overlap one another to define a refrigerant passage. An oxidant gas inlet port and a fuel gas inlet port are provided in the upper portion of the power generating unit, and an oxidant gas outlet port and a fuel gas outlet port are provided in the lower portion of the power generating unit. A refrigerant inlet port and a refrigerant outlet port are formed in each of the left and right portions of the power generating unit.

1 . A fuel cell stack formed by stacking power generation units together, the power generation units each being formed by stacking an electrolyte electrode assembly and a metal separator having a rectangular shape in a plan view, the electrolyte electrode assembly including a pair of electrodes and an electrolyte interposed between the electrodes, the fuel cell stack comprising:
 a corrugated gas flow field formed on a surface of the metal separator facing the electrode for supplying a fuel gas or an oxygen-containing gas as a reactant gas along the electrode;   a coolant flow field formed as a back surface of the corrugated gas flow field, between the power generation units;   reactant gas supply passages and reactant gas discharge passages for flowing the reactant gases and which extend through one pair of opposite sides of the metal separator in a stacking direction; and   a pair of coolant supply passages and a pair of coolant discharge passages for flowing a coolant and which extend through the other opposite sides of the metal separator in the stacking direction, the pair of the coolant supply passages and the pair of the coolant discharge passages being positioned adjacent to at least the reactant gas supply passages or the reactant gas discharge passages, the pair of the coolant supply passages being disposed separately on the other opposite sides of the metal separator, and the pair of the coolant discharge passages being disposed separately on the other opposite sides of the metal separator.   
     
     
         2 . The fuel cell stack according to  claim 1 , wherein the metal separator is elongated longitudinally;
 an oxygen-containing gas supply passage and a fuel gas supply passage serving as the reactant gas supply passages extend through one end side of the metal separator in a longitudinal direction of the metal separator;   an oxygen-containing gas discharge passage and a fuel gas discharge passage serving as the reactant gas discharge passages extend through the other end side of the metal separator in the longitudinal direction;   the pair of the coolant supply passages or the pair of the coolant discharge passages are positioned by the corrugated gas flow field and adjacent to the oxygen-containing gas supply passage and the fuel gas supply passage of the metal separator, and are disposed separately in a lateral direction of the metal separator; and   the pair of the coolant discharge passages or the pair of the coolant supply passages are positioned by the corrugated gas flow field and adjacent to the oxygen-containing gas discharge passage and the fuel gas discharge passage of the metal separator, and are disposed separately in the lateral direction.   
     
     
         3 . The fuel cell stack according to  claim 1 , wherein the metal separator is elongated longitudinally in the direction of gravity, and the metal separator and the electrolyte electrode assembly are stacked in a horizontal direction. 
     
     
         4 . The fuel cell stack according to  claim 1 , wherein the metal separator is elongated longitudinally,
 an oxygen-containing gas supply passage serving as the reactant gas supply passage and a fuel gas discharge passage serving as the reactant gas discharge passage extend through one end side of the metal separator in a longitudinal direction of the metal separator; and   an oxygen-containing gas discharge passage serving as the reactant gas discharge passage and a fuel gas supply passage serving as the reactant gas supply passage extend through the other end side of the metal separator in the longitudinal direction;   the pair of the coolant supply passages or the pair of the coolant discharge passages are positioned by the corrugated gas flow field and adjacent to the oxygen-containing gas supply passage and the fuel gas discharge passage of the metal separator, and are disposed separately in a lateral direction of the metal separator; and   the pair of the coolant discharge passages or the pair of the coolant supply passages are positioned by the corrugated gas flow field and adjacent to the oxygen-containing gas discharge passage and the fuel gas supply passage of the metal separator, and are disposed separately in the lateral direction.   
     
     
         5 . The fuel cell stack according to  claim 1 , wherein the metal separator is elongated longitudinally in a horizontal direction, and the metal separator and the electrolyte electrode assembly are stacked in the direction of gravity. 
     
     
         6 . The fuel cell stack according to  claim 1 , wherein an inlet buffer is provided at a position connecting the corrugated gas flow field and the reactant gas supply passage;
 an outlet buffer is provided at a position connecting the corrugated gas flow field and the reactant gas discharge passage; and   in the coolant flow field, the coolant flows at least through the back surface of the outlet buffer.   
     
     
         7 . The fuel cell stack according to  claim 2 , wherein the pair of the coolant supply passages and the pair of the coolant discharge passages are positioned within a spacing interval in the lateral direction between an outer end of an opening of at least the oxygen-containing gas supply passage or the oxygen-containing gas discharge passage and an outer end of an opening of at least the fuel gas supply passage or the fuel gas discharge passage. 
     
     
         8 . A fuel cell stack formed by stacking power generation units together, the power generation units each being formed by stacking an electrolyte electrode assembly and a separator having a rectangular shape in a plan view, the electrolyte electrode assembly including a pair of electrodes and an electrolyte interposed between the electrodes, the fuel cell stack comprising:
 a gas flow field formed on a surface of the separator facing the electrode for supplying a fuel gas or an oxygen-containing gas as a reactant gas along the electrode;   a coolant flow field formed between the power generation units;   reactant gas supply passages and reactant gas discharge passages for flowing the reactant gases and which extend through one pair of opposite sides of the separator in a stacking direction; and   a pair of coolant supply passages and a pair of coolant discharge passages for flowing a coolant and which extend through the other opposite sides of the separator in the stacking direction, the pair of the coolant supply passages and the pair of the coolant discharge passages being positioned adjacent to at least the reactant gas supply passages or the reactant gas discharge passages, the pair of the coolant supply passages being disposed separately on the other opposite sides of the separator, the pair of the coolant discharge passages being disposed separately on the other opposite sides of the separator.   
     
     
         9 . The fuel cell stack according to  claim 8 , wherein the separator is elongated longitudinally,
 the reactant gas supply passages and the reactant gas discharge passages extend through short sides of the separator; and   the coolant supply passages and the coolant discharge passages extend through opposite long sides of the separator.   
     
     
         10 . The fuel cell stack according to  claim 9 , wherein the coolant supply passages and the coolant discharge passage have longitudinally-elongated shapes which extend along the long sides. 
     
     
         11 . A fuel cell stack formed by stacking a plurality of power generation units together, the power generation units each being formed by stacking an electrolyte electrode assembly and a metal separator having a rectangular shape in a plan view, the electrolyte electrode assembly including a pair of electrodes and an electrolyte interposed between the electrodes, the fuel cell stack comprising:
 reactant gas supply passages and reactant gas discharge passages extending through one pair of opposite sides of the power generation unit in a stacking direction;   a coolant supply passage and a coolant discharge passage extending through the other opposite sides of the power generation unit in the stacking direction, the coolant supply passage being positioned adjacent to the reactant gas supply passages and the coolant discharge passage being positioned adjacent to the reactant gas discharge passages;   corrugated oxygen-containing gas flow grooves formed on a surface of one of adjacent metal separators facing the electrode for supplying an oxygen-containing gas as one reactant gas along the electrode, and corrugated fuel gas flow grooves formed on a surface of the other of the adjacent metal separators facing the electrode for supplying the fuel gas as the other reactant gas along the electrode; and   a coolant flow field formed between the adjacent power generation units by ridges on the back surface of the corrugated oxygen-containing gas flow grooves and ridges on the back surface of the corrugated fuel gas flow grooves,   wherein the respective ridges on the back surfaces are set at different phases in an upstream area adjacent to the coolant supply passage and in a downstream area adjacent to the coolant discharge passage, and are set at the same phase in an intermediate area where the flow direction of the coolant is the same as at least the flow direction of the oxygen-containing gas or the fuel gas.   
     
     
         12 . The fuel cell stack according to  claim 11 , wherein the corrugated oxygen-containing gas flow grooves or the corrugated fuel gas flow grooves include phase reversing sections where phase reversal occurs between the upstream and downstream areas and the intermediate area. 
     
     
         13 . The fuel cell stack according to  claim 11 , wherein the corrugated oxygen-containing gas flow grooves or the corrugated fuel gas flow grooves include straight sections through which a phase shift by a half-phase is caused between the upstream and downstream areas and the intermediate area. 
     
     
         14 . The fuel cell stack according to  claim 11 , wherein the metal separator is elongated longitudinally;
 the oxygen-containing gas supply passage and the fuel gas supply passage serving as the reactant gas supply passages extend through an upper end side of the metal separator in a longitudinal direction thereof;   the oxygen-containing gas discharge passage and the fuel gas discharge passage serving as the reactant gas discharge passages extend through a lower end side of the metal separator in the longitudinal direction; and   on opposite sides of the metal separator in a lateral direction thereof, a pair of the coolant supply passages are positioned adjacent to the oxygen-containing gas supply passage and the fuel gas supply passage, and a pair of the coolant discharge passages are positioned adjacent to the oxygen-containing gas discharge passage and the fuel gas discharge passage.