Abstract: A fuel cell stack includes at least one fuel cell having a fuel inlet for directing a hydrogen fuel to the fuel cell to generate electric current; a sensor cell having an anode, a cathode and a membrane between the anode and the cathode, the anode being communicated with the fuel inlet to receive a portion of fuel from the fuel inlet, the sensor cell being connected across the stack to carry the electric current whereby hydrogen from the portion of fuel is electrochemically pumped to the cathode of the sensor cell; and a sensor communicated with the sensor cell to receive a signal corresponding to evolution of hydrogen from the anode to the cathode of the sensor cell and adapted to detect contaminants in the fuel based upon the signal.

Abstract: A decontamination procedure for a fuel cell power plant (10) includes operating the plant to produce electrical power for an operating period, and then terminating operation of the plant (10) for a decontamination period, and then, whenever optimal electrical production of a plant fuel cell (12) is reduced by at least 5% by contaminants adsorbed by fuel cell electrodes (24, 42), decontaminating the fuel cell (12) of the plant (10) during the decontamination period by oxidizing contaminants adsorbed by electrodes (24, 42) of the fuel cell. Oxidizing the contaminants may be accomplished by various steps including exposing the electrodes (24, 42) to flowing oxygen; to heated flowing oxygen; to a sequence of start-stop cycles; and, to varying controlled potentials.

Abstract: A fuel cell power plant includes a fuel cell having a membrane electrode assembly (MEA), disposed between an anode support plate and a cathode support plate, the anode and/or cathode support plates include a hydrophilic substrate layer having a predetermined pore size. The pressure of the reactant gas streams is greater than the pressure of the coolant stream, such that a greater percentage of the pores within the hydrophilic substrate layer contain reactant gas rather than water. Any water that forms on the cathode side of the MEA will migrate through the cathode support plate and away from the MEA. Controlling the pressure also ensures that the coolant water will continually migrate from the coolant stream toward the anode side of the MEA, thereby preventing the membrane from becoming dry. Proper pore size and a pressure differential between coolant and reactants improves the electrical efficiency of the fuel cell.

Abstract: Each cell of a fuel cell stack is provided, between the anode 37 and cathodes 38, with either (a) a permanent shunt (20) which may be a discrete resistor (42-44), a diode (95), a strip of compliant carbon cloth (65), or a small amount of conductive carbon black (22) in the ionomer polymer mixture of which the proton exchange membrane (39) is formed, or (b) a removeable shunt such as a conductor (69) which may be rotated into and out of contact with the fuel cell anodes and cathodes, or a conductor (85) which may be urged into contact by means of a shape memory alloy actuator spring (90, 91), which may be heated.

Abstract: The invention is a start up system and method for a fuel cell power plant (10) using a purging of the cathode flow field (38) with a hydrogen rich reducing fluid fuel to minimize corrosion of the cathode electrode (16). The method for starting up the shut down fuel cell power plant (10) includes the steps of: a. purging the cathode flow field (38) with the reducing fluid fuel; b. then, directing the reducing fluid fuel to flow through an anode flow field (28); c. next, terminating flow of the fuel through the cathode flow field (38) and directing an oxygen containing oxidant to flow through the cathode flow field (38); and, d. finally, connecting a primary load (70) to the fuel cell (12) so that electrical current flows from the fuel cell (12) to the primary load (70).

Abstract: The invention is a start up system and method for a fuel cell power plant (10) using a purging of the cathode flow field (38) with a hydrogen rich reducing fluid fuel to minimize corrosion of the cathode electrode (16). The method for starting up the shut down fuel cell power plant (10) includes the steps of: a. purging the cathode flow field (38) with the reducing fluid fuel; b. then, directing the reducing fluid fuel to flow through an anode flow field (28); c. next, terminating flow of the fuel through the cathode flow field (38) and directing an oxygen containing oxidant to flow through the cathode flow field (38); and, d. finally, connecting a primary load (70) to the fuel cell (12) so that electrical current flows from the fuel cell (12) to the primary load (70).

Abstract: A fuel cell power plant includes a fuel cell having a membrane electrode assembly (MEA), disposed between an anode support plate and a cathode support plate, the anode and/or cathode support plates include a hydrophilic substrate layer having a predetermined pore size. The pressure of the reactant gas streams is greater than the pressure of the coolant stream, such that a greater percentage of the pores within the hydrophilic substrate layer contain reactant gas rather than water. Any water that forms on the cathode side of the MEA will migrate through the cathode support plate and away from the MEA. Controlling the pressure also ensures that the coolant water will continually migrate from the coolant stream toward the anode side of the MEA, thereby preventing the membrane from becoming dry. Proper pore size and a pressure differential between coolant and reactants improves the electrical efficiency of the fuel cell.

Abstract: Each cell of a fuel cell stack is provided, between the anode 37 and cathodes 38, with either (a) a permanent shunt (20) which may be a discrete resistor (42-44), a diode (95), a strip of compliant carbon cloth (65), or a small amount of conductive carbon black (22) in the ionomer polymer mixture of which the proton exchange membrane (39) is formed, or (b) a removeable shunt such as a conductor (69) which may be rotated into and out of contact with the fuel cell anodes and cathodes, or a conductor (85) which may be urged into contact by means of a shape memory alloy actuator spring (90, 91), which may be heated.

Abstract: A PEM fuel cell oxidant flow field plate (12) having a substantial portion (77A) of the flow field formed of interdigitated reactant flow channels (86, 87) includes a humidification zone coextensive with an electrolyte dry-out barrier (38). Within the humidification zone, the reactant flow channels are flow-through channels (89), which permits the inlet reactant flow to be sufficiently slow to permit adequate humidification of the inlet reactant gas from adjacent water, such as coolant water flow channels and/or the anode, to avoid electrolyte dry-out.

Abstract: A PEM fuel cell oxidant flow field plate (12) having a substantial portion (77A) of the flow field formed of interdigitated reactant flow channels (86,87) includes a humidification zone coextensive with an electrolyte dry-out barrier (38). Within the humidification zone, the reactant flow channels are flow-through channels (89), which permits the inlet reactant flow to be sufficiently slow to permit adequate humidification of the inlet reactant gas from adjacent water, such as coolant water flow channels and/or the anode, to avoid electrolyte dry-out.

Abstract: Fuel Cell Having a Hydrophilic Substrate Layer A fuel cell power plant includes a fuel cell having a membrane electrode assembly (MEA), disposed between an anode support plate and a cathode support plate, the anode and/or cathode support plates include a hydrophilic substrate layer having a predetermined pore size. The pressure of the reactant gas streams is greater than the pressure of the coolant stream, such that a greater percentage of the pores within the hydrophilic substrate layer contain reactant gas rather than water. Any water that forms on the cathode side of the MEA will migrate through the cathode support plate and away from the MEA. Controlling the pressure also ensures that the coolant water will continually migrate from the coolant stream toward the anode side of the MEA, thereby preventing the membrane from becoming dry. Proper pore size and a pressure differential between coolant and reactants improves the electrical efficiency of the fuel cell.

Abstract: A process for regenerating a selective oxidizer bed, by the introduction of oxygen is provided. In a single oxidizer bed environment, regeneration may be carried out on shut-down or on start-up. On start-up, the process includes providing a selective oxidizer bed as well a fuel processor. The selective oxidizer bed is heated to approximately 180° F. Air is passed through the selective oxidizer bed while maintaining the selective oxidizer bed at a temperature of approximately 180° F. for 1-2 minutes. The selective oxidizer is then purged with steam to remove residual air therefrom. Fuel is then introduced from the fuel processor into the selective oxidizer. On shut-down, residual fuel is purged from the oxidizer bed and then air is passed therethrough while maintaining the bed at a temperature between approximately 180° F. to approximately 220° F. The oxidizer is allowed to cool to ambient temperature and then heated to 180° F.