Abstract: Flow field plates for fuel cells may include an interior region bounded by an interior boundary that contains openings which, when the flow field plates are stacked, form plural headers extending along a fuel cell stack. A flow field may surround the interior boundary. The headers may include headers for fuel, oxidant and coolant for example. The flow field may include elements that direct flow of a reactant in a radial direction and/or in a circumferential direction. A fuel cell stack may be enclosed in a housing that compresses the stack. In some embodiments plural fuel cells are combined in a power unit in which the fuel cell stacks are received within a fuel cell block equipped with a fluid manifolding stack interface that provides fluid interfaces to the headers of the fuel cell stack.

Abstract: A fuel cell electric power generation system using air as both a coolant and an oxidant comprises an electric power generation subsystem, an air filter subsystem, a power and control electronics unit (PEU) subsystem comprising a DC/DC converter, and an air fan subsystem. The subsystems are arranged such that air circulation through the system is improved and the risk of moisture damage to sensitive PEU components is reduced. In one embodiment, the air filter subsystem is positioned ahead of the PEU subsystem, which is positioned ahead of the power generation subsystem, which is positioned ahead of the air fan subsystem in the direction of air flow, such that air is drawn by the air fan subsystem through the air filter subsystem, over the PEU subsystem, and through the electric power generation subsystem, providing filtered air to cool the PEU prior to entering the fuel cell stack to provide oxygen for the electrochemical reaction.