Patent ID: 8802311

Claim:
A fuel cell stack structure, comprising: a plurality of unit cells, each having an aperture formed therethrough; a first fuel cell stack formed by stacking the plurality of unit cells in a stacking direction, the first fuel cell stack having an internal manifold opening defined by the apertures of the plurality of unit cells, the internal manifold opening in communication with an internal manifold; an in-cell fluid passage in fluid communication with the internal manifold, the in-cell fluid passage configured and arranged to flow fluid in a direction generally perpendicular to the stacking direction of the unit cell; an external manifold having an external passage for supplying the fluid to the internal manifold, the external passage having a connection portion to connect the external passage to the internal manifold; and a convex surface protruding from an interior surface of the connecting portion, wherein the convex surface is configured to create a vortex in the fluid proximal to the internal manifold.