Polymer electrolyte fuel cell stack and method for operating the same and gas vent valve

A method for operating a polymer electrolyte fuel cell stack comprising a plurality of membrane electrode assemblies each including a first gas diffusion electrode on one side of an ion exchange membrane and a second gas diffusion electrode on the other side;

• a plurality of reactant gas supply separators, each disposed between two of the plurality of membrane electrode assemblies;
• and a water supply manifold for supplying water to each of the plurality of reactant gas supply separators;
• wherein
• each one of the reactant gas supply separators includes:
• a first surface which faces the first gas diffusion electrode of one of the membrane electrode assemblies and has first reactant gas supply grooves for supplying first reactant gas;
• and a second surface which faces to the second gas diffusion electrode of another one of the membrane electrode assemblies and has second reactant gas supply grooves for supplying second reactant gas;
• the operating method includes supplying water to the plurality of first reactant gas supply grooves, wherein the step of supplying water comprising:
• introducing water from the water supply manifold to at least one water supply groove disposed on the second surface above the water supply manifold;
• guiding water from the water supply groove through a buffer section along the second surface, the buffer section being disposed on and extending along the second surface, and having a porous body;
• and
• guiding water which has passed through the buffer section, from the second surface to the first surface through a communication hole.

A method for operating a polymer electrolyte fuel cell stack comprising a plurality of membrane electrode assemblies each including a first gas diffusion electrode on one side of an ion exchange membrane and a second gas diffusion electrode on the other side;

• a plurality of reactant gas supply separators, each disposed between two of the plurality of membrane electrode assemblies;
• and a water supply manifold for supplying water to each of the plurality of reactant gas supply separators;
• wherein:
• each one of the reactant gas supply separators includes:
• a first surface which faces the first gas diffusion electrode of one of the membrane electrode assemblies and has first reactant gas supply grooves for supplying first reactant gas;
• and a second surface which faces to the second gas diffusion electrode of another one of the membrane electrode assemblies and has second reactant gas supply grooves for supplying second reactant gas;
• the operating method includes water supply step of supplying water to the plurality of first reactant gas supply grooves, wherein the step of supplying water comprising:
• introducing water from the water supply manifold to at least one water supply groove disposed on the second surface above the water supply manifold;
• guiding water from the water supply groove through a buffer section along the second surface, the buffer section being disposed on and extending along the second surface, and having a porous body;
• guiding water which has passed through the buffer section, from the second surface to the first surface through a communication hole;
• the polymer electrolyte fuel cell stack comprises:
• a gas vent hole which is connected to and positioned above the buffer section;
• a pipe connected to the gas vent hole;
• and a pressure loss element connected to the pipe;
• and
• the operating method further comprising a step of continuously exhausting part of the water from the polymer electrolyte fuel cell stack, from the buffer section through the gas vent hole and the pressure loss element, so that pressure in the gas vent hole may be held higher than supply pressure of the first reactant gas during operation of the polymer electrolyte fuel cell stack.

A polymer electrolyte fuel cell stack comprising:

• a plurality of membrane electrode assemblies each including a first gas diffusion electrode on one side of an ion exchange membrane and a second gas diffusion electrode on the other side;
• a plurality of reactant gas supply separators, each disposed between two of the plurality of membrane electrode assemblies;
• and
• a water supply manifold for supplying water to each of the plurality of reactant gas supply separators is formed;
• wherein:
• each one of the reactant gas supply separators includes:
• a first surface which faces the first gas diffusion electrode of one of the membrane electrode assemblies and has first reactant gas supply grooves for supplying first reactant gas;
• a second surface which faces to the second gas diffusion electrode of another one of the membrane electrode assemblies and has second reactant gas supply grooves for supplying second reactant gas;
• and water supply means for supplying water to the plurality of first reactant gas supply grooves;
• the water supply means includes:
• at least one water supply groove formed on the second surface for introducing water from the water supply manifold;
• one or more communication holes for communicating from the second surface to the first surface;
• and a buffer section which is formed on the second surface and has a porous body for substantially uniformly distributing water from the water supply groove to the communication holes formed in a plurality of the reactant gas supply separators;
• the porous body extends along the second surface so that water can flow through the porous body along the second surface;
• and
• the buffer sections each has a water non-permeable lid in contact with the porous body, wherein
• the water non-permeable lid comprises a plate having such rigidity that the lid would have substantially no bending at the water supply groove and the buffer section when the fuel cell stack is fastened, and an elastic sheet which deforms in compression is disposed on the opposite side of a side contacting the porous body of each lid.

A polymer electrolyte fuel cell stack comprising:

• a plurality of membrane electrode assemblies each including a first gas diffusion electrode on one side of an non exchange membrane and a second gas diffusion electrode on the other side;
• a plurality of reactant gas supply separators, each disposed between two of the plurality of membrane electrode assemblies;
• and
• a water supply mold for supplying water to each of the plurality of reactant gas supply separators;
• wherein:
• each one of the reactant gas supply separators includes:
• a first surface which faces the first gas diffusion electrode of one of the membrane electrode assemblies and has first reactant gas supply grooves for supplying first reactant gas;
• a second surface which faces to the second gas diffusion electrode of another one of the membrane electrode assemblies and has second reactant gas supply grooves for supplying second reactant gas;
• and water supply means for supplying water to the plurality of first reactant gas supply grooves;
• the water supply means includes:
• at least one water supply groove formed on the second surface for introducing water from the water supply manifold;
• one or more communication holes for communicating from the second surface to the first surface;
• and a buffer section which is formed on the second surface and has a porous body for substantially uniformly distributing water from the water supply groove to the communication holes formed in a plurality of the reactant gas supply separators;
• the porous body extends along the second surface so that water can flow through the porous body along the second surface;
• and
• the membrane electrode assemblies and reactant gas supply separators are arranged substantially upright;
• and the communication holes are positioned higher than the water supply grooves, so that the first reactant gas can flow substantially downward through the first reactant gas supply grooves, accompanied by water which has passed through the communication holes, wherein
• the water supply manifold for supplying water is positioned below the buffer section.