Reactant manifolds for fuel cell stacks operating below freezing

A solid polymer electrolyte fuel cell stack comprising a plurality of solid polymer electrolyte fuel cells stacked in series, each fuel cell comprising an anode, a cathode, a solid polymer electrolyte, at least one reactant inlet duct, and at least one reactant outlet duct, and the stack comprising a reactant outlet manifold having a length, width, and height, wherein the reactant outlet manifold comprises a manifold outlet and a plurality of manifold inlets fluidly connected to the reactant outlet ducts of each fuel cell, wherein the reactant outlet manifold comprises:

• a closed end region and an open end region,
• a divider dividing the manifold into an upper duct section directly connected to the manifold inlets and a lower main flow section directly connected to the manifold outlet, wherein the divider comprises a plurality of ports fluidly connecting the upper duct section to the lower main flow section, the ports adapted for draining water from the upper duct section to the lower main flow section;
• and
• at least one separating wall in the upper duct section partially separating the upper duct section into flow segments, each flow segment including manifold inlets and at least one port, the separating wall adapted for directing part of the reactant flow from the upper duct section into the lower duct section via the ports,
• wherein the reactant is oxidant, the at least one reactant outlet duct is at least one oxidant outlet duct, and the reactant outlet manifold is an oxidant outlet manifold.