Abstract: Fuel cell reactant gas flow field plates (53, 84, 104) have flow channels (71, 98, 105, 106), with transverse portions (73, 100, 109) some of which have more than one groove (78, 79; 101, 103; 111, 112; 117, 118), thereby to adjust the planform shape of the reactant gas flow field.

Abstract: An inlet fuel distributor (10-10d) has a permeable baffle (39, 54, 54a, 60) between a fuel supply pipe (11, 83) and a fuel inlet manifold (12, 53, 53a, 63) causing fuel to be uniformly distributed along the length of the fuel inlet manifold. A surface (53, 68) may cause impinging fuel to turn and flow substantially omnidirectionally improving its uniformity. Recycle fuel may be provided (25, 71) into the flow downstream of the fuel inlet distributor. During startup, fuel or inert gas within the inlet fuel distributor and the fuel inlet manifold may be vented through a valve (57, 86) in response to a controller (58, 79) so as to present a uniform fuel front to the inlets of the fuel flow fields (58).

Abstract: Fuel is provided to an inlet (14) of a cascade region (15) which has a plurality of stages (17-23), each of which divides fuel flow evenly into a pair of corresponding slots (24-26). The flow is then spread across a floor surface (41) of a cascade exit header (40), the flow spreading into areas between the slots. The flow is then directed into an open cavity which is in fluid communication with the inlets of the fuel flow fields (12) of the fuel cells, reaching the fuel flow field inlets uniformly and simultaneously.