Patent ID: 7803497

Claim:
A fuel cell stack comprising: a plurality of fuel cells each including a plurality of parallel reactant gas flow channels; a reactant gas inlet manifold providing a reactant gas to the flow channels in each fuel cell; a reactant gas outlet manifold receiving the reactant gas from the flow channels in each fuel cell; a first actuation device positioned within the inlet manifold; and a second actuation device positioned within the outlet manifold, wherein the first and second actuation devices are selectively actuated in a direction parallel to the flow in the plurality of reactant gas flow channels so that inlet ends of a first set of alternating flow channels of the plurality of flow channels are closed and outlet ends of a second set of opposite and alternating flow channels of the plurality of flow channels are closed in each fuel cell to provide interdigitated flow through the plurality of flow channels, wherein the first actuation device and the second actuation device are mounted to end plates of the fuel cell stack.