Abstract: Flow-field for a PEM fuel cell having a plurality of flow-channels including flow-restrictors strategically located throughout to achieve desired pressure differentials between fuel and oxidant supply and exhaust manifolds, and between adjacent flow-channels. A preferred flow-restrictor comprises a constriction in the flow channel that has a cross-sectional area that is less than the cross-sectional area of the flow-channel.

Abstract: Flow-field for a PEM fuel cell having a plurality of flow-channels including flow-restrictors strategically located throughout to achieve desired pressure differentials between fuel and oxidant supply and exhaust manifolds, and between adjacent flow-channels. A preferred flow-restrictor comprises a constriction in the flow channel that has a cross-sectional area that is less than the cross-sectional area of the flow-channel.

Abstract: Flow-field for a PEM fuel cell having a plurality of flow-channels including flow-restrictors strategically located throughout to achieve desired pressure differentials between fuel and oxidant supply and exhaust manifolds, and between adjacent flow-channels. A preferred flow-restrictor comprises a constriction in the flow channel that has a cross-sectional area that is less than the cross-sectional area of the flow-channel.

Abstract: A current-collecting plate of a PEM fuel cell has a reaction gas flow-field comprising a plurality of flow-channels each having an inlet leg communicating with a fuel supply manifold, an exit leg communicating with a fuel exhaust manifold, and a branched midsection intermediate the inlet and exit legs.

Abstract: A current-collecting plate of a PEM fuel cell has a reaction gas flow-field comprising a plurality of flow-channels each having an inlet leg communicating with a fuel supply manifold, an exit leg communicating with a fuel exhaust manifold, and a branched midsection intermediate the inlet and exit legs.

Abstract: A PEM fuel cell having serpentine flow field channels each having an inlet leg, an exit leg, at least one medial leg therebetween, and hairpin curved ends connecting the medial leg(s) to other legs of the sector. Each leg is separated from the next by a tapering land so that it converges/diverges on/from the next adjacent leg (i.e. its longitudinal centerline intersects the longitudinal centerline of an adjacent leg).

Abstract: A PEM fuel cell having serpentine flow field channels each having an inlet leg, an exit leg, at least one medial leg therebetween, and hairpin curved ends connecting the medial leg(s) to other legs of the sector. Each leg is separated from the next by a tapering land so that it converges/diverges on/from the next adjacent leg (i.e. its longitudinal centerline intersects the longitudinal centerline of an adjacent leg).

Abstract: A PEM fuel cell having serpentine flow field channels wherein each channel has an inlet leg, an exit leg, at least one medial leg therebetween and hairpin curves connecting the legs to each other. The legs all extend in the same general direction between a gas supply and gas exhaust manifold. One of the inlet and exit legs is longer than the other while the medial leg is shorter than the shortest of the inlet/exit leg. The land(s) defining the medial leg(s) of adjacent channels are generally aligned lengthwise.

Abstract: A method of heating a cold MEA to accelerate cold start-up of a PEM fuel cell. The MEA is locally heated from below freezing to a suitable operating temperature by the exothermal chemical reaction between H2 and O2 on the anode and/or cathode catalysts. To their end, H2 is introduced into the O2-rich cathode feed stream and/or O2 is introduced into the H2-rich anode feed stream.

Abstract: A PEM fuel cell having serpentine flow field channels comprising a plurality of serially-linked serpentine segments extending between inlet and exhaust manifolds. Each segment has an inlet leg, an exit leg, at least one medial leg therebetween and hairpin curved ends connecting the medial leg(s) to other legs of the segment. A bridging section of each flow channel connects adjacent segments of the same channel one to the next. The hairpin-curved ends of the medial legs are spaced from bridging sections by different distances depending on the difference in pressure in the bridging section and the hairpin-curved ends.

Abstract: A PEM fuel cell having serpentine flow field channels wherein the input/inlet legs of each channel border the input/inlet legs of the next adjacent channels in the same flow field, and the output/exit legs of each channel border the output/exit legs of the next adjacent channels in the same flow field. The serpentine fuel flow channels may be longer, and may contain more medial legs, than the serpentine oxidant flow channels.