Abstract: A fuel cell stack assembly includes a plurality of substantially uniform fuel cell components arranged in a stack and including end components; and pressure/end plate current collectors positioned adjacent to the end components.

Abstract: The invention is a hydrogen passivation shut down system for a fuel cell power plant (10). An anode flow path (24) is in fluid communication with an anode catalyst (14) for directing hydrogen fuel to flow adjacent to the anode catalyst (14), and a cathode flow path (38) is in fluid communication with a cathode catalyst (16) for directing an oxidant to flow adjacent to the cathode catalyst (16) of a fuel cell (12). Hydrogen fuel is permitted to transfer between the anode flow path (24) and the cathode flow path (38). A hydrogen reservoir (66) is secured in fluid communication with the anode flow path (24) for receiving and storing hydrogen during fuel cell (12) operation, and for releasing the hydrogen into the fuel cell (12) whenever the fuel cell (12) is shut down.

Abstract: A fuel cell power plant (10) includes a fuel cell (12) having a membrane electrode assembly (MEA) (16), disposed between an anode support plate (14) and a cathode support plate (18), the anode and/or cathode support plates include a hydrophilic substrate layer (80, 82) having a predetermined pore size. The pressure of the reactant gas streams (22, 24) is greater than the pressure of the coolant stream (26), 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 polymer electrolyte membrane (PEM) fuel cell power plant is cooled evaporatively by a non-circulating pressurized water coolant system. The coolant system utilizes a hydrophobic porous plug for bleeding air from the coolant water while maintaining coolant back pressure in a coolant flow field of the system. Furthermore, there is a first method for identifying appropriate parameters of the hydrophobic porous plug for use with a known particular coolant system; and a second method for determining proper operating conditions for a fuel cell water coolant system which can operate with a hydrophobic porous plug closure having known physical parameters.

Abstract: A fuel cell (40) includes first and second catalysts (12?), (14?) secured to opposed surfaces of an electrolyte (16?); a first flow field (26?) secured in fluid communication with the first catalyst (12?) defining a plurality of flow channels (30A?, 30B?, 30C?, 30D?) between a plurality of ribs (32A?, 32B?, 32C?, 32D?, 32E?) of the first flow field (26?); and a backing layer (42) secured between the first flow field (26?) and the first catalyst (12?). The backing layer (42) includes a carbon black, a hydrophobic polymer, and randomly-dispersed carbon fibers (44). The carbon fibers (44) are at least twice as long as a width (46) of the flow channels (30A?, 30B?, 30C?, 30D?) defined in the adjacent first flow field (26?). The backing layer (42) replaces a known substrate (22) and diffusion layer (18).

Abstract: In a fuel cell stack, an inlet fuel distributor (15, 31, 31a, 31b) comprises a plurality of fuel distributing passageways (17-23, 40-47, 64) of substantially equal length and equal flow cross section to uniformly distribute fuel cell inlet fuel from a fuel supply conduit (13, 14, 50) to a fuel inlet manifold (28). The conduits may be either channels (40-47; 64) formed within a plate (39) or tubes (17-23). The channels may have single exits (65) or double exits (52, 53) into the fuel inlet manifold.

Abstract: The medium (9), such as water, of a container (10), such as a fuel cell accumulator, is kept above freezing by a hydrogen/oxygen catalytic combustor (13) fed hydrogen from a source comprising a mechanical thermostatic valve (25) in thermal communication (26) with the container (10) and connected to a hydrogen supply (28). The combustor may comprise an ejector (32) having hydrogen through its primary inlet (31) drawing air through a secondary inlet (33). The combustor may comprise a diffusion combustor having a catalyst (38) spaced from a heating surface (30) and a diffusion control plate (40) low partial pressure of oxygen at the catalyst causing diffusion through the barrier. Water vapor from combustion condenses on a surface (146) and is led by hydrophilic woven carbon paper (126) to wicking material (133), which has smaller pores than the carbon paper, which leads the water downwardly, through a disk (140) and plugs (147) to atmospheric air.

Abstract: Fuel cells (38) have water passageways (67; 78, 85; 78a, 85a) that provide water through reactant gas flow field plates (74, 81) to cool the fuel cell. The water passageways may be vented to atmosphere (99), by a porous plug (69), or pumped (89, 146) with or without removing any water from the passageways. A condenser (59, 124) receives reactant air exhaust, may have a contiguous reservoir (64, 128), may be vertical, (a vehicle radiator, FIG. 2), may be horizontal, contiguous with the top of the fuel cell stack (37, FIG. 5), or below (124) the fuel cell stack (120). The passageways may be grooves (76, 77; 83, 84) or may comprise a plane of porous hydrophilic material (78a, 85a) contiguous with substantially the entire surface of one or both of the reactant gas flow field plates. Air flow in the condenser may be controlled by shutters (155). The condenser may be a heat exchanger (59a) having freeze-proof liquid flowing through a coil (161) thereof, the amount being controlled by a valve (166).

Abstract: Fuel cells (38) have minute water passageways (67) that provide water through one or both reactant gas flow field plates (74, 82) of each fuel cell, whereby the fuel cell is cooled convectively. The water passageways (67; 78, 85; 78a, 85a) may be vented by a porous plug (69), or by a microvacuum pump (89) that does not pump any water from the passageways, or simply vented (99) to atmosphere. A condenser (59) may have a contiguous reservoir (64); the condenser (59) may be vertical, such as a vehicle radiator (FIG. 1), or may be horizontal, contiguous with the top of the fuel cell stack (37, FIG. 5). The passageways may be grooves (76, 77; 83, 84) in the reactant gas flow plates (75, 81) or the passageways may comprise a plane of porous hydrophilic material (78a, 85a) contiguous with substantially the entire surface of one or both of the reactant gas flow field plates.

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 hydrogen passivation shut down system for a fuel cell power plant (10). An anode flow path (24) is in fluid communication with an anode catalyst (14) for directing hydrogen fuel to flow adjacent to the anode catalyst (14), and a cathode flow path (38) is in fluid communication with a cathode catalyst (16) for directing an oxidant to flow adjacent to the cathode catalyst (16) of a fuel cell (12). Hydrogen fuel is permitted to transfer between the anode flow path (24) and the cathode flow path (38). A hydrogen reservoir (66) is secured in fluid communication with the anode flow path (24) for receiving and storing hydrogen during fuel cell (12) operation, and for releasing the hydrogen into fuel cell (12) whenever the fuel cell (12) is shut down.

Abstract: The invention is a hydrogen passivation shut down system for a fuel cell power plant (10). An anode flow path (24) is in fluid communication with an anode catalyst (14) for directing hydrogen fuel to flow adjacent to the anode catalyst (14), and a cathode flow path (38) is in fluid communication with a cathode catalyst (16) for directing an oxidant to flow adjacent to the cathode catalyst (16) of a fuel cell (12). Hydrogen fuel is permitted to transfer between the anode flow path (24) and the cathode flow path (38). A hydrogen reservoir (66) is secured in fluid communication with the anode flow path (24) for receiving and storing hydrogen during fuel cell (12) operation, and for releasing the hydrogen into fuel cell (12) whenever the fuel cell (12) is shut down.

Abstract: Recycle fuel gas is provided (36) to an impeller (34, 34a) for application to the input (24) of the anode flow fields of a fuel cell stack (25). The impeller may be an ejector (34) having its primary input (33) connected to a source (11) of hydrogen and its secondary input (35) connected to the outlet (27, 37) of the fuel cells anode flow fields. The ejector outlet provides the minimum fuel flow required at the lowest power rating. The impeller may be an electrochemical hydrogen pump (34a) with a constant current generator (50) providing for a substantially constant recycle flow (the highest not more than double the lowest), and one pressure regulator (20) providing minimum flow of fresh fuel to the fuel inlets of the first stack. Pressure regulators (20, 21) control the amount of fresh fuel to the anode flow fields for power in excess of minimum power.

Abstract: The direction of flow of purged fuel reactant gas (20) is sensed (38, 39, 44, 53, 54) to ensure it flows outwardly from a fuel cell stack (9) towards the ambient (21). If the purged fuel reactant. gas is not flowing outwardly, a signal (39) causes a controller (26) to open the circuit (35) thereby disconnecting the electrical load (33) from the fuel cell stack.

Abstract: Fuel cell power plants (19, 47, 60, 86, 102, 112, 121) include recycle fuel from a fuel exit (29) of the last fuel flow field (23, 52, 64, 89) of a series of flow fields (20-23; 49-52; 61-64; 87-89) labeled M?N through M, applied either to the Mth flow fields or both the Mth and the (M?1)th flow fields. The fuel recycle impeller is a blower (30), a turbocompressor (30a) driven by an air exhaust, an ejector (30b) or an electrochemical hydrogen pump (30c). Fuel from a source (77) may be applied both to the first fuel flow field (87) and an additional fuel flow field (88, 74, 75, 89) of a series of flow fields to reduce pressure drop and flow rate requirements in the first of the series of flow fields and assure more fuel in the additional fuel flow field. Flow to the additional fuel flow field may be controlled by voltage (126) in such field or fuel content (128) of its exhaust. Transient fuel volume is provided by a tank (125).

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 fuel cell (40) includes first and second catalysts (12?), (14?) secured to opposed surfaces of an electrolyte (16?); a first flow field (26?) secured in fluid communication with the first catalyst (12?) defining a plurality of flow channels (30A?, 30B?, 30C?, 30D?) between a plurality of ribs (32A?, 32B?, 32C?, 32D?, 32E?) of the first flow field (26?); and a backing layer (42) secured between the first flow field (26?) and the first catalyst (12?). The backing layer (42) includes a carbon black, a hydrophobic polymer, and randomly-dispersed carbon fibers (44). The carbon fibers (44) are at least twice as long as a width (46) of the flow channels (30A?, 30B?, 30C?, 30D?) defined in the adjacent first flow field (26?). The backing layer (42) replaces a known substrate (22) and diffusion layer (18).

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: In a fuel cell stack, an inlet fuel distributor (15, 31, 31a, 31b) comprises a plurality of conduits of substantially equal length and equal flow cross section to uniformly distribute fuel cell inlet fuel from a fuel supply pipe (13) to a fuel inlet manifold (28). The conduits may be either channels (40-47; 64; 67) formed within a plate (39) or tubes (17-23). The channels may have single exits (65) or double exits (52, 53) into the fuel inlet manifold.

Abstract: The invention is a hydrogen passivation shut down system for a fuel cell power plant (10). An anode flow path (24) is in fluid communication with an anode catalyst (14) for directing hydrogen fuel to flow adjacent to the anode catalyst (14), and a cathode flow path (38) is in fluid communication with a cathode catalyst (16) for directing an oxidant to flow adjacent to the cathode catalyst (16) of a fuel cell (12). Hydrogen fuel is permitted to transfer between the anode flow path (24) and the cathode flow path (38). A hydrogen reservoir (66) is secured in fluid communication with the anode flow path (24) for receiving and storing hydrogen during fuel cell (12) operation, and for releasing the hydrogen into fuel cell (12) whenever the fuel cell (12) is shut down.