Abstract: The invention is a porous carbon body for a fuel cell having an electronically conductive hydrophilic agent and method of manufacture of the body. The porous carbon body comprises an electronically conductive graphite powder in an amount of between 60%-80% by weight of the body; a carbon fiber in an amount of between 5%-15% by weight of the body; a thermoset binder in an amount of between 6%-18% by weight of the body; and, a modified carbon black electronically conductive hydrophilic agent in an amount of between 2%-20% by weight of the body. The body provides for increased wettability without any decrease in electrical conductivity, and also provides for an efficient manufacture without any need for high temperature, costly steps to graphitize the body, or to incorporate post molding hydrophilic agents into pores of the body.

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: An improved water management system for PEM fuel cells is provided. Catalyst layers are disposed on both sides of a proton exchange membrane. Porous plates are positioned adjacent the catalyst layers. Water transport plates are positioned adjacent the porous plates and the reactant gas are humidified at their inlets, in one embodiment by fins, while moisture is removed in the fuel flow path and at the oxidant outlet, in one embodiment by other fins.

Abstract: The invention is a system (10) and method for determining a gas composition within a fuel cell (12) of a shut down fuel cell power plant. The system (10) includes at least one fuel cell (12), a sensor circuit (86) secured in electrical connection with the fuel cell (12), wherein the circuit (86) includes a power source (88), a voltage-measuring device (90), and a sensor circuit switch (92). The circuit (86) is secured so that the power source (88) may selectively deliver a predetermined sensing current to the fuel cell (12) for a pre-determined sensing duration. The system (10) selectively admits the reducing fluid into an anode flow field (28) of the cell (12) whenever the sensor circuit (86) senses that a shut down monitoring voltage of the fuel cell (12) is the same as or exceeds a calibrated sensor voltage limit of the fuel cell (12).

Abstract: A PEM fuel cell system includes a plurality of PEM fuel cells arranged in a stack having two opposed, outwardly facing end surfaces; pressure plates positioned relative to said end surfaces for securing said PEM fuel cells in said stack; and spacer members between said end surfaces and said pressure plates for thermally insulating said end surfaces from said pressure plates.

Abstract: A vehicle (150) includes a fuel cell stack (151) started when the stack is below freezing, by connection (158) to the vehicle propulsion system (159) within a few seconds of starting the flow of fuel (179) and oxidant (173), or when open circuit voltage (155, 156) is detected. The fuel is in excess of stochiometry requirement and the oxidant is in excess of at least twice stochiometric requirement, either may be at about atmospheric pressure or at 4 kPa (0.6 psi) or more above the pressure of any water in said water passages, and either may be below freezing. Water transport plates (84, 86, 88, 89) have water passages connected to a water circulation loop (170) including a reservoir (164) having an auxiliary heater (161) connected (160) to the stack. Warming of cell stack materials and ice in the water transport plates, heat of fusion of melting ice, warming of melted water, and evaporative cooling of water melted in the water transport plates keep the fuel cell cool until liquid coolant can be circulated.

Abstract: A method for shutting down a fuel cell system including a plurality of fuel cells arranged in a stack, includes cooling the fuel cells to a shutdown temperature while maintaining a substantially uniform water vapor pressure through the fuel cells whereby migration of water within the fuel cells during cooling is reduced.

Abstract: A vehicle (150) includes a fuel cell stack (151) started when the stack is below freezing, by connection (158) to the vehicle propulsion system (159) within a few seconds of starting the flow of fuel (179) and oxidant (173), or when open circuit voltage (155, 156) is detected. The fuel is in excess of stochiometry requirement and the oxidant is in excess of at least twice stochiometric requirement, either may be at about atmospheric pressure or at 4 kPa (0.6 psi) or more above the pressure of any water in said water passages, and either may be below freezing. Water transport plates (84, 86, 88, 89) have water passages connected to a water circulation loop (170) including a reservoir (164) having an auxiliary heater (161) connected (160) to the stack. Warming of cell stack materials and ice in the water transport plates, heat of fusion of melting ice, warming of melted water, and evaporative cooling of water melted in the water transport plates keep the fuel cell cool until liquid coolant can be circulated.

Abstract: The invention is a system and method for shutting down a fuel cell power plant having at least one fuel cell, a primary load, and an auxiliary load that receive electrical current from electrodes of the fuel cell through an external circuit. Shutting down the plant includes disconnecting the primary load; terminating flow of the oxidant through a cathode flow field; connecting the auxiliary load to consume oxygen within the fuel cell; disconnecting the auxiliary load; connecting a power supply to the fuel cell electrodes to increase a concentration of hydrogen within the cathode flow field; and, then, decreasing or eliminating flow of hydrogen into an anode flow field after an equilibrium gas concentration of at least 0.0001% hydrogen, balance fuel cell inert gases, is achieved in both the anode and cathode flow fields.

Abstract: Performance of a fuel cell stack (12) is recovered following long term decay by connecting (51) an auxiliary load (50) to the fuel cell while shutting off one or more of oxidant inlet valve (27a), oxidant pressure regulating valve (28a) or oxidant pump (26), which all may be achieved with a controller (46), to cyclically starve the cathode of oxidant so that it achieves hydrogen potential, e.g., less than 0.1 volts, for on the order of tens of seconds, repetitively, such as at every 10 or 20 seconds, while the auxiliary load remains connected, initially drawing 10 to 100 mASC, for example. Complete rejuvenation is obtained following 1800 or more cycles over a period of five or more hours.

Abstract: A fuel cell stack (7) has an auxiliary load (30) in series with a battery (29) which can selectively (25) be connected across the fuel cell stack in place of a main load (24). A method includes connecting the battery and auxiliary load across the fuel cell stack while providing fuel (13) to the anode flow fields (8, 10); in one embodiment, oxidant (17) is provided to the cathode flow fields (16) initially; in a second embodiment, oxidant is withheld from the cathode flow for a predetermined time or until a threshold voltage is reached.

Abstract: A procedure for shutting down an operating fuel cell system includes disconnecting the primary electricity using device and stopping the flow of hydrogen containing fuel to the anode, followed by quickly displacing the residual hydrogen with air by blowing air through the anode fuel flow field. A sufficiently fast purging of the anode flow field with air eliminates the need for purging with an inert gas such as nitrogen.

Abstract: A procedure for starting up a fuel cell system that is disconnected from its primary load and has both its cathode and anode flow fields filled with air includes initiating a flow of air through the cathode flow field and rapidly displacing the air in the anode flow field by delivering a flow of fresh hydrogen containing fuel into the anode flow field, and thereafter connecting the primary load across the cell. Sufficiently fast purging of the anode flow field with hydrogen prior to connecting the cells to the load eliminates the need for purging the anode flow field with an inert gas, such as nitrogen, upon start-up.

Abstract: A procedure for starting up a fuel cell system that is disconnected from its primary load and that has air in both its cathode and anode flow fields includes a) connecting an auxiliary resistive load across the cell to reduce the cell voltage; b) initiating a recirculation of the anode flow field exhaust through a recycle loop and providing a limited flow of hydrogen fuel into that recirculating exhaust; c) catalytically reacting the added fuel with oxygen present in the recirculating gases until substantially no oxygen remains within the recycle loop; disconnecting the auxiliary load; and then d) providing normal operating flow rates of fuel and air into respective anode and cathode flow fields and connecting the primary load across the cell. The catalytic reaction may take place on the anode or within a catalytic burner disposed within the recycle loop.

Abstract: The invention is a porous carbon body for a fuel cell having an electronically conductive hydrophilic agent and method of manufacture of the body. The porous carbon body comprises an electronically conductive graphite powder in an amount of between 60%-80% by weight of the body; a carbon fiber in an amount of between 5%-15% by weight of the body; a thermoset binder in an amount of between 6%-18% by weight of the body; and, a modified carbon black electronically conductive hydrophilic agent in an amount of between 2%-20% by weight of the body. The body provides for increased wettability without any decrease in electrical conductivity, and also provides for an efficient manufacture without any need for high temperature, costly steps to graphitize the body, or to incorporate post molding hydrophilic agents into pores of the body.

Abstract: A gas injection method for treating an electrochemical fuel cell stack assembly, the fuel cell stack assembly being repeatedly injected with an oxidizing gas at critical locations along the fuel cell stack assembly so that the fuel supply and the oxidizing gas will chemically react to reduce at least one harmful contaminant within the fuel supply. The preferred gas injection method treats a fuel cell stack assembly to reduce the debilitating effects of extraneous carbon monoxide within the fuel supply and thus preserves the efficient operation of the fuel cell stack assembly.

Abstract: A PEM fuel cell (12) operating on substantially pure hydrogen (32) and air (26) has an exhaust flow control valve (37) at the exit of the anode fuel reactant flow field, said valve being normally closed during steady state low or medium power operation, so that the concentration of nitrogen in the fuel reactant flow fields, by diffusion across the membrane from the cathode, will approach the average concentration of nitrogen in the oxidant, thereby limiting the concentration of hydrogen to a corresponding low complementary amount, which reduces the diffusion of hydrogen across the membrane for consumption at the cathode, thereby increasing the efficiency of operation of the fuel cell. A current sensor (40) allows a controller (46) to open an exhaust flow control valve (37), thereby drawing much higher amounts of hydrogen into the fuel reactant flow field of the anode to support generation of power at high current densities without hydrogen starvation.

Abstract: A procedure for shutting down an operating fuel cell system that recirculates a portion of the anode exhaust in a recycle loop, includes disconnecting the primary load from the external circuit, stopping the flow of air to the cathode, and applying an auxiliary resistive load across the cells to reduce and/or limit cell voltage and reduce the cathode potential while fuel is still flowing to the anode and the anode exhaust is recirculating. The fuel flow is then stopped, but the anode exhaust continues to be circulated in the recycle loop to bring the hydrogen therein into contact with a catalyst in the presence of oxygen to convert the hydrogen to water, such as in a catalytic burner. The recirculating is continued until substantially all the hydrogen is removed. The cell may then be completely shut down. No inert gas purge is required as part of the shut-down process.

Abstract: Disclosed is a fuel cell stack assembly for use in a fuel cell power plant and for producing electricity from fuel and oxidizer reactants. The fuel cell stack assembly includes a plurality of individual fuel cells each having an electrolytic medium, a cathode and an anode, and the cell stack assembly is adapted for defining anode flow fields for exposing the anodes to a fuel, cathode flow fields for exposing the cathodes to an oxidant. Also included are input and output manifolds defining input and output inner volumes in fluid communication with the cathode flow fields, and at least one blower mounted with one of the manifolds for flowing oxidizer through cathode flow fields. The blower can be mounted within an inner volume defined by a manifold, and can be a vane axial or centrifugal blower, and can be driven by a variable speed motor. Multiple blowers can be associated with the cell stack assembly, and can either push or pull (or both) the oxidizer through the cathode flow fields.

Abstract: Reactant air is drawn through a fuel cell stack (11) by a pump (38) connected to the air exhaust manifold (29). The fuel exhaust (19, 43) may be connected to the air exhaust (39) before either being released to atmosphere through a duct (44), or consumed in a catalytic converter (47). The fuel cell power plant may be disposed within a casing (52) so that the fuel exhaust (55) and/or all fuel leaks may mix with the fresh incoming air (56, 59) and be reacted on the cathode catalysts to form water. A fuel cell (10c) may have a low profile configuration suitable for mounting beneath the passenger compartment of an automobile.