Abstract: A reduced volume fuel cell stack (10) includes a plurality of thin fuel cells (46, 48, 50, 52, 54) and a plurality of thick fuel cells (56, 58). The thin fuel cells include water management channels (62A, 62B, 62C, 62D) and the thick fuel cells include cooling channels (76A, 76B, 76C, 76D). At least two thin fuel cells (48, 50) are secured adjacent each other and adjacent each thick fuel cell (56, 58) within the stack (10). The water management channels (62A, 62B, 62C, 62D) have a depth that is at least four times less than a depth of the cooling channels (76A, 76B, 76C, 76D) so that volume, weight and water content of the stack (10) are reduced.

Abstract: A fuel cell system that includes fuel processing components, such as a reformer and shift converter, for converting an organic fuel to hydrogen, is shut-down by disconnecting the fuel cell from its load and purging the fuel processing components of residual hydrogen with a flow of air. The purge air may be forced through the components in series or in parallel, using a blower; or, the purge air may be allowed to enter the components through a low inlet, whereupon the air rises through the components by natural circulation and exits through a high outlet, along with the residual hydrogen.

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 fuel cell stack has a cascaded fuel flow field in which groups (10-12) of fuel cells (13, 13a) are arranged in flow-series, there being a fuel purge inlet valve (33) to provide fuel flow directly to two of the groups (11-12) downstream in the series, and a fuel purge outlet valve (36) to vent fuel flow directly from the first and second groups (10, 11) of fuel cells (13), whereby to avoid large pressure drop in the lowest group (12) of the series, to thereby facilitate quick purging of the fuel flow field. In other embodiments, rotary gates (40, 41) or sliding gates (56, 57) within manifolds cause fuel to flow into and out of all three groups directly during a purge.

Abstract: A shift converter, or reactor, (16HT, 16LT) in a fuel processing subsystem (14, 16HT, 16LT, 18), as for a fuel cell (12), uses an improved catalyst bed (34, 50) and the addition of oxygen (40, 40A, 40B, 40C, 40D, 41A, 41B, 41C, 41D) to reduce the amount of carbon monoxide in a process gas stream. The catalyst of bed (34, 50) is a metal, preferably a noble metal, having a promoted support of metal oxide, preferably ceria and/or zirconia. A water gas shift reaction converts carbon monoxide to carbon dioxide. The oxygen may be introduced as air, and causes an improvement in carbon monoxide removal. Use of the added oxygen enables the shift reactor (16HT, 16LT) and its catalyst bed (34, 50) to be relatively more compact for performing a given level of carbon monoxide conversion. The catalyst bed (34, 50) obviates the requirement for prior reducing of catalysts, and minimizes the need to protect the catalyst from oxygen during operation and/or shutdown.

Abstract: A control method and arrangement (48, 50, 150, I, T, P, FFL) are provided in a fuel cell power plant (10) for regulating (48, FC) fuel flow to a steam-based fuel processing system (FPS) (14) associated with a low-temperature fuel cell stack assembly (12). A portion of the fuel provided by the FPS (14) is used to provide steam for the FPS. The fuel flow to the FPS is regulated as a function of the power demand (I) on the fuel cell (12) and at least the enthalpy of the steam (P, T), such that the steam enthalpy is regulated to meet increases and decreases in power demand without exceeding steam pressure limits. In addition to reliance on-steam pressure (P) as a fundamental measure of steam enthalpy, the control may additionally use reaction temperature (T) at, or in, a reformer, such as a catalytic steam reformer (132), to regulate fuel flow and thus, steam enthalpy.

Abstract: A keep warm system for a fuel cell, power plant (10), typically of the PEM type, prevents freeze-sensitive portions of the power plant, such as the cell stack assembly (CSA) (12) and the water management system (28, 30), from freezing under extreme cold external temperatures, during extended storage (CSA shut-down) periods. Pre-stored and pressurized fuel, typically hydrogen (25), normally used to fuel the anode (16) of the CSA, is used as fuel for a catalytic oxidation reaction at a catalytic burner (66) to produce heated gas that convectively passes in heat exchange relation with the freeze sensitive portions (12, 28, 30) of the power plant (10). The convective flow of the heated gases induces the air flow to the burner (66), obviating the need for parasitic electrical loads.

Abstract: A proton exchange membrane (PEM) fuel cell includes fuel and oxidant flow field plates (26, 40) having fuel and oxidant channels (27, 28; 41, 44), and water channels, the ends (29, 48) of which that are adjacent to the corresponding reactant gas inlet manifold (34, 42) are dead ended, the other ends (31, 50) draining excess water into the corresponding reactant gas exhaust manifold (36, 45). Flow restrictors (39, 47) maintain reactant gas pressure above exit manifold pressure, and may comprise interdigitated channels (65, 66; 76, 78). Solid reactant gas flow field plates have small holes (85, 88) between reactant gas channels (27, 28; 41) and water drain channels (29, 30; 49, 50). In one embodiment, the fuel cells of a stack may be separated by either coolant plates (51) or solid plates (55) or both.

Abstract: A fuel cell power plant includes a fuel cell having a membrane electrode assembly (MEA), which is disposed between anode and cathode support plates. Porous water transport plates or the support plates have interdigitated flow channels for the reactant gas streams to pass through and conventional flow channels for coolant streams to pass through. The pressure of the reactant gas streams is greater than the coolant stream which, within the porous water transport plates allows the coolant water to saturate the water transport plates thereby forcing the reactant gases into the anode and cathode support plates. This, in turn, increases the mass transfer of such gases into the support plates, thereby increasing the electrical performance of the fuel cell. Current densities of about 1.6 amps per square centimeter are achieved with air stochiometries of not over 2.50.

Abstract: A fuel cell power plant with enhanced water recovery includes a fuel cell power plant adapted to receive a reducing fluid and an oxidant and to generate therefrom electricity and an at least partially saturated exhaust stream; a mass and energy transfer device defining a first flow passage for the wet exhaust stream and a second flow passage for an oxidant stream, the first flow passage being in mass transfer relationship with the second flow passage; and an apparatus for cooling at least one of the oxidant stream, the exhaust stream and the mass and energy transfer device, whereby water is transferred from the exhaust stream to the oxidant stream so as to produce an at least partially saturated oxidant stream. A method is also disclosed.

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 fuel gas reformer assemblage for use in a fuel cell power plant is formed from a composite plate assembly which includes spaced-apart divider plates with columns of individual gas passages. The reformer assemblage is constructed from a series of repeating sub-assemblies, each of which includes a core of separate regenerator/heat exchanger gas passages. The core in each sub-assembly is sandwiched between a pair of reformer gas passage skins, which complete the assembly. Adjacent reformer gas/regenerator/reformer gas passage sub-assemblies in the composite plate assembly are separated from each other by burner gas passages. The regenerator/heat exchanger gas passages and the reformer gas passages in each sub-assembly are connected by gas flow reversing manifolds which form a part of each sub-assembly.

Abstract: A start system for enabling rapid fuel cell power from sub-freezing initial conditions in a fuel cell power plant which comprises heating an antifreeze coolant source and melting ice in the sump of a cell stack assembly with the heated antifreeze to effect start up.

Abstract: The invention is a fuel cell stack having an improved pressure plate and current collector. The fuel cell stack includes a plurality of fuel cell component plates stacked adjacent each other to form a reaction portion of the fuel cell stack. A current collector is secured adjacent a first end of the stack of fuel cell component plates and a pressure plate is secured adjacent to the current collector. The current collector is made from a non-porous, electrically conductive graphite material and includes at least one conductive stud secured to the collector. The pressure plate is made of an electrically non-conductive, non-metallic, fiber reinforced composite material, so that the current collector and pressure plate are light, compact and have a low thermal capacity.

Abstract: A stack of plates (121) (such as fuel cells, electrochemical cells, or enthalpy exchange plates) is surrounded by a sleeve manifold (119) which is shaped to provide manifold chambers (34-39; 146-149; 151-153; 156-158; 161-163; 180-187), and including surfaces (142) for seals (143) to isolate the manifold chambers from each other. Sleeve manifolds (119a, 119b, 119c) may be formed of material of varying thickness, by machining, casting, or extrusion, or may be formed of material (119d) of uniform thickness by bending, casting or extrusion. Sleeve manifolds may be formed of metal, graphite, plastic or reinforced plastic.

Abstract: A site management system (11) is provided for a power system (8) at site in a utility distribution grid (10). The power system (8) includes multiple fuel cell power plants (18) and one or more loads (14), for selective connection/disconnection with the grid (10) The site management system (11) controls the power plants (18) in an integrated manner, alternatively in a grid connected mode and a grid independent mode. The multiple power plants (18) at the site may be viewed and operated as a unified distributed resource on the grid (10). The site management system (11) provides signals representative of the present power capability (Kw Capacity—88) of each of the power plants (18), and a signal (Total Kw Capacity—95) representative of the total present power capability at the site. These power representations are used to appropriately assign power dispatch loadings to the respective fuel cells (18) in the grid connected mode and in the grid independent mode, and may also be used for load shedding.

Abstract: A fuel gas-steam reformer assembly, preferably an autothermal reformer assembly, for use in a fuel cell power plant, includes a catalyst bed which is formed from a cylindrical monolithic open cell foam body. The foam body is preferably formed from a high temperature material such as stainless steel, nickel alloys and Iron-aluminum alloys, or from a ceramic material. The foam body includes open cells or pores which are contained within the metal or ceramic lattice. The lattice is coated with a porous wash coat which serves as a high surface area substrate onto which catalysts used in the reformer are applied. The foam body has an inlet end into which a mixture of fuel, steam and air is fed to begin the reforming process. An inlet portion of the foam body may be provided with an iron oxide and/or noble metal catalyst and the remainder of the foam body may be provided with a copper, copper/zinc and/or noble metal catalyst.

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 unitized electrode assembly for a fuel cell stack assembly, includes a membrane electrode assembly having a first side, a second side, a peripheral edge area and a plurality of perforations along the peripheral edge area; a cathode substrate adjacent to the first side; an anode substrate adjacent to the second side; and a seal material bonding the cathode substrate to the anode substrate and extending through the plurality of perforations.