Abstract: A fuel cell power plant having a plurality of functionally integrated components including a fuel cell assembly provided with a fuel stream, an oxidant stream and a coolant stream. The fuel cell power plant functionally integrates a mass and heat recovery device for promoting a transfer of thermal energy and moisture between a first gaseous stream and a second gaseous stream, and a burner for processing the fuel exhausted from the fuel cell assembly during operation thereof. A housing chamber is utilized in which the oxidant stream exhausted from the fuel cell assembly merges with a burner gaseous stream exhausted from the burner. The resultant airflow from the common chamber is directed back to the mass and heat recovery device as the first gaseous stream.

Abstract: A coolant system is proposed for addressing temperature concerns during start-up and shut-down of a cell stack assembly. The coolant system comprises a coolant exhaust conduit in fluid communication with a coolant exhaust manifold and a coolant pump, the coolant exhaust conduit enabling transportation of exhausted coolant away from a coolant exhaust manifold. A coolant return conduit is provided to be in fluid communication with a coolant inlet manifold and a coolant pump, the coolant return conduit enabling transportation of the coolant to the coolant inlet manifold. The coolant system further includes a bypass conduit in fluid communication with the coolant exhaust conduit and the coolant return conduit, while a bleed valve is in fluid communication with the coolant exhaust conduit and a gaseous stream. Operation of the bleed valve enables venting of the coolant from the coolant channels, and through said bypass conduit.

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 interposed 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 sub-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 burner gas stream and the process gas stream flow in opposite directions through the assemblage. A varying heat transfer fin density population is disposed in the burner gas passage so as to control the peak burner wall temperatures encountered during operation of the assemblage. The burner wall peak temperature is preferably no greater than about 1,700° F.

Abstract: A fuel cell having a polymer electrolyte membrane (16) between anode (14) and cathode (18) reactant flow fields includes a variable blower (32), the power control signal (61) of which is provided by a controller (75) in response to a current signal (63) indicative of the current of the load (71) sensed by a current detector (68). The controller responds to a schedule of blower power as a function of load current density to provide a stochiometry, S, which is fixed at a stochiometry of A, plus or minus a range of stochiometries, D, below a certain current density, C, and varies with higher current densities as: S=[A+B(i−C)]±D, where B is he slope of stochiometry as a function of current density, and i is the actual current density.

Abstract: A fuel cell stack (7) has a two-pass fuel flow field (11, 14) extending from a fuel inlet (8) around a fuel turnaround manifold (12) to a fuel outlet (15). The stack has two air flow fields (37, 40) extending from an air inlet (32) through an air turnaround manifold (38) to an air outlet (41), the air outlet (41) being adjacent to the fuel outlet (15). The stack includes a coolant flow field (23, 25, 27) which extends from a coolant inlet (21) to a coolant outlet (28), the coolant inlet being adjacent to both the fuel outlet and the air outlet. The fluid flow configuration provides lower temperature, a more even temperature profile, a higher coolant exit temperature, and permits operation with higher air utilization and lower coolant flow.

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 method is proposed for increasing the operational efficiency of a fuel cell power plant including a cell stack assembly comprised of a plurality of fuel cells in electrical communication with one another. The cell stack assembly includes a fuel inlet manifold and a fuel exhaust manifold for accepting and exhausting, respectively, a reactant fuel stream. The proposed method includes providing the cell stack assembly with the reactant fuel stream, sealing the fuel exhaust manifold for a first predetermined time period, thereby preventing the reactant fuel stream from exiting the cell stack assembly and opening the fuel exhaust manifold for a second predetermined time period.

Abstract: The invention is a freeze tolerant fuel cell power plant that includes at least one fuel cell and a water transport plate secured within the fuel cell having a coolant inlet and a coolant outlet that direct a water coolant through the plate. A suction water displacement system includes a freeze tolerant accumulator secured to the coolant inlet and a vacuum separator secured to the coolant outlet having a suction generating eductor secured to the separator. Control valves and a coolant pump selectively direct either the water coolant, heated, or unheated water immiscible fluid to cycle from the accumulator, through the coolant inlet, water transport plate, coolant outlet, vacuum separator and back to the accumulator in order to permit operation and storage of the plant in sub-freezing ambient temperatures.

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 precooler for use in a fuel cell system between a thermal reformer and a shift converter includes an atomizing water inlet in combination with a swirling inducing reformed gas inlet which act to increase the resistance time of the reformed gas in the precooler so as to effectively cool same.

Abstract: A fuel cell power plant has a fuel cell (38) receiving hydrogen (37) from a fuel processing system (12) which employs a vaporizer (19) to vaporize clean gasoline from a source (13). A conventional start burner (22) and startup heat exchanger (28) are utilized to convert water (31) from the fuel processing system (12) and fuel cell (38) into steam (32); but during sub-zero startup, an aqueous antifreeze solution (46) is provided to the heat exchanger (28) to produce the steam (32) for starting the vaporization of gasoline in the vaporizer (19).

Abstract: A fuel processing method is operable to remove substantially all of the sulfur present in an undiluted oxygenated hydrocarbon fuel stock supply which contains an oxygenate and which is used to power an internal combustion engine in a mobile environment, such as an automobile, bus, truck, boat, or the like, or in a stationary environment. The fuel stock can be gasoline, diesel fuel, or other like fuels which contain relatively high levels of organic sulfur compounds such as mercaptans, sulfides, disulfides, and the like. The undiluted hydrocarbon fuel supply is passed through a nickel reactant desulfurizer bed wherein essentially all of the sulfur in the organic sulfur compounds reacts with the nickel reactant, and is converted to nickel sulfide, while the desulfurized organic remnants continue through the remainder of the fuel processing system. The method can be used to desulfurize either a liquid or a gaseous fuel stream, which contains an oxygenate such as MTBE, ethanol, methanol, or the like.

Abstract: The invention is a freeze tolerant fuel cell power plant that includes at least one fuel cell; a coolant loop having a coolant circulating device that directs a water coolant through a water transport plate within the fuel cell; and a water displacement system having a freeze tolerant accumulator that contains a water immiscible fluid and water coolant. The water displacement system also includes a water immiscible fluid pump, heater and displacement valves for directing the water immiscible fluid to flow from the accumulator into the coolant loop; for directing the water coolant in the coolant loop to flow into the accumulator; and, for directing heated water immiscible fluid to flow from the accumulator into the coolant loop and back into the accumulator.

Abstract: The invention is a fuel cell with an electrolyte dry-out barrier to restrict loss of water from the electrolyte. The fuel cell includes: an anode catalyst and a cathode catalyst secured to opposed sides of an electrolyte; an anode flow field disposed adjacent the anode catalyst for directing the reducing fluid to pass adjacent the anode catalyst, and a cathode flow field disposed adjacent the cathode catalyst for directing the process oxidant stream to pass adjacent the cathode catalyst; and, an anode electrolyte dry-out barrier secured between the electrolyte and the anode flow field for restricting transfer of water from the electrolyte into the anode flow field. The anode electrolyte dry-out barrier extends from adjacent an entire reducing fluid inlet and along an entire reducing fluid flow path a distance that is adequate for the reducing fluid stream flowing through the anode flow field to become saturated with water.

Abstract: Method and apparatus for changing the state of operation of a fuel cell, such as starting the fuel cell up or shutting the fuel cell down, are disclosed. An idle load is applied to the fuel cell when the cell temperature is between about normal operating temperature and a transition temperature, and fuel and oxidizer are supplied to the fuel cell commensurate with the power delivered to the idle load. Below the transition temperature, purging/passivation procedures known in the art can be followed, and an open or dummy load applied to the fuel cell. At normal operating temperature or above a service load is applied to the fuel cell.

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: A reactant gas manifold (6), to be used with a fuel cell stack (17) having a flat seal surface (16), is provided with a convex seal surface (13) so that when the manifold (6) is distorted by being bolted (20) to the fuel cell stack, the distortion will provide substantially uniform seal pressure along the length of the seal between the surfaces (13, 16).

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 fine pore enthalpy exchange barrier is disclosed for use with a fuel cell power plant. The barrier includes a flexible support matrix that defines pores and a liquid transfer medium that fills the pores creating a gas barrier. An inlet surface of the fine pore enthalpy exchange barrier is positioned in contact with a process oxidant inlet stream entering a fuel cell power plant, and an opposed exhaust surface of the barrier is positioned in contact with an exhaust stream exiting the plant so that water and heat exchange from the exhaust stream directly into the process oxidant inlet stream to heat and humidify the stream as it enters the plant. The flexible support matrix defines hydrophilic pores having a pore-size range of about 0.1-100 microns and results in a bubble pressure that is greater than 0.2 pounds per square inch. The liquid transfer medium may include water, aqueous salt solutions, aqueous acid solutions, or organic antifreeze water solutions.