Abstract: A proton exchange membrane fuel cell including a membrane electrode assembly comprising a proton transmissive membrane, a catalytic anode layer on one face of the membrane, and a catalytic cathode layer on the other face of the membrane. The fuel cell further includes a gas distribution layer on each of the cathode and anode layers defining a gas flow field extending over each of the catalytic layers. The membrane electrode assembly has a convoluted configuration whereby to increase the ratio of membrane area to planar fuel cell area and thereby increase the electrical output of the fuel cell for a given planar area size fuel cell. The convoluted configuration of the membrane electrode assembly also facilitates the division of the gas distribution layers into separate parallel channels thereby allowing the use of an inexpensive foam material for the gas distribution layers irrespective of the inherent variations in porosity of foam materials.

Abstract: A fuel cell system that extracts water from the effluent of a fuel cell for supply to other components of the fuel cell system that require water. A preferred embodiment is a fuel cell system, for the production of electricity from hydrogen gas and an oxidant, comprising: (a) a fuel cell comprising an anode input for a hydrogen-containing anode supply stream, a cathode input for an oxidant-containing cathode supply stream, and a cathode output for cathode effluent comprising water produced by said fuel cell; and (b) a water transfer device, connected to said fuel cell, that transfers water from said cathode effluent to said anode supply stream.

Abstract: A composite separator plate for a fuel cell having a low-carbon loading and a high-polymer loading is disclosed. The separator plate composition includes a percentage of conductive fibrous filler having a relatively high aspect-ratio oriented through the thickness of the plate to achieve desired electrical and thermal conductivity requirements. A method of manufacturing the fuel separator plate having such fibers disposed in a through-plane orientation is also disclosed. The method includes forming a separator plate having a land height for orienting the fibers in a desired through-plane direction, then removing a portion of the land height to obtained the desired geometric configuration for the separator plate.

Abstract: A control apparatus and method for efficiently controlling the amount of heat generated by a fuel cell processor in a fuel cell system by determining a temperature error between actual and desired fuel processor temperatures. The temperature error is converted to a combustor fuel injector command signal or a heat dump valve position command signal depending upon the type of temperature error. Logic controls are responsive to the combustor fuel injector command signals and the heat dump valve position command signal to prevent the combustor fuel injector command signal from being generated if the heat dump valve is opened or, alternately, from preventing the heat dump valve position command signal from being generated if the combustor fuel injector is opened.

Abstract: A method and apparatus for detecting leakage current in the coolant of a fuel cell stack. The invention eliminates the use of a conductivity sensor by using a voltmeter to measure the voltage across the coolant. If the coolant voltage is at or below a predetermined level, an excessive level of conductivity in the coolant exists, and the presence of leakage current is reported. The invention can also compare the coolant voltage to two different predetermined voltage levels, the second one higher than the first. A coolant voltage at or below the lower voltage level could signal a shut down of the stack, while a coolant voltage at or below the higher voltage level could signal an alarm or another diagnostic. The invention can optionally use a second voltmeter to measure the voltage across the stack and calculate the resistivity and conductivity of the coolant.

Abstract: A method and apparatus for injecting oxygen into a fuel cell reformate stream to reduce the level of carbon monoxide while preserving the level of hydrogen in a fuel cell system.

Abstract: The invention provides a novel method for controlling the oxidant injection to a reactor by determining fluctuations in the requirements from monitoring the flow rates and pressures of an upstream reactor. The method is used to oxidize carbon monoxide in a hydrogen-rich reformate stream supplied to a fuel cell.

Abstract: A proton exchange membrane fuel cell comprising a proton transmissive membrane, a catalytic anode layer on one face of the membrane, a catalytic cathode layer on the other face of the membrane, and a gas distribution layer on each of the cathode and anode layers defining a gas flow field extending over each of the catalytic layers. Each of the gas distribution layers comprises a layer of open cell conductive foam material which is divided into a plurality of generally parallel segments extending from one edge of the fuel cell to an opposite edge of the fuel cell whereby to define a plurality of generally parallel porous reactant paths extending across each catalytic layer. The segments may be defined by selectively varying the porosity of the foam material or selectively varying the thickness of the foam material.

Abstract: An apparatus for monitoring hydrogen and optionally a non-hydrogen gas including carbon monoxide. The apparatus includes a sensor assembly consisting of a plurality of electrochemical cells sequentially arranged in a path of the hydrogen-containing gas stream. Reaction and consumption of hydrogen at catalytically reactive surface areas of the cells generates a current which is proportional to the amount of hydrogen in the gas stream entering the sensor.

Abstract: A method of making a membrane electrode assembly is provided. The method includes using a porous support to control the drying of the electrode, and the use of wettable and non-wettable solvents to control the seepage of ionomer into the porous support.

Abstract: In one aspect, the present invention provides a method for operating a fuel cell system. The system comprises a reactor having one or more catalytic beds and is fed a hydrocarbon fuel along with air and steam. Where more than one catalytic bed is present, such catalytic beds are preferably arranged sequentially such that the outlet from one bed enters the inlet of the next bed. The catalytic beds are the regions where reactions among the hydrocarbon, air, and steam are catalyzed within the reactor. The method comprises supplying a stream of a fuel and air mixture to the reactor which is lean. The mixture is lean in that it has an excess amount of oxygen relative to the stoichiometric amount required for reaction with the fuel. The reactions occurring with the lean mixture heat the reactor. When there is more than one catalytic bed, the hot gases generated from one catalytic bed can be used to heat other catalytic beds.

Abstract: A bipolar plate assembly for a PEM fuel cell having a serpentine flow field formed on one side and an interdigitated flow field formed on the opposite side such that a single plate member is usable as an anode current collector and a cathode current collector of adjacent fuel cells. The bipolar plate assembly further includes a staggered seal arrangement to direct gaseous reactant flow through the fuel cell such that the seal thickness is maximized while the repeat distance between adjacent fuel cells is minimized.

Abstract: A method and apparatus for injecting oxygen into a fuel cell reformate stream to reduce the level of carbon monoxide while preserving the level of hydrogen in a fuel cell system.

Abstract: A regenerative braking system and method for a batteriless fuel cell vehicle includes a fuel cell stack, a plurality of ancillary loads, and a regenerative braking device that is coupled to at least one wheel of the vehicle. The regenerative braking device powers ancillary loads when the vehicle is coasting or braking. The fuel cell powers the loads when the vehicle is accelerating or at constant velocity. The regenerative braking device dissipates power in an air supply compressor when the vehicle is traveling downhill to provide brake assistance. The compressor can be run at high airflow and high pressure to create an artificially high load. A bypass valve is modulated to adjust the artificially high load of the compressor. A back pressure valve protects the fuel cell stack from the high airflow and pressure. A controller controls a brake torque of the regenerative braking device as a function of vehicle speed and modulates the bypass valve.

Abstract: A water separator especially suitable for use in a vehicular fuel cell system. The separator comprises a housing defining an inlet, an outlet, and a longitudinal through passage extending therebetween. A central shaft extends along the passage and a plurality of modular baffles are stacked on the shaft. Each baffle includes an annular hub portion received on the shaft and a plurality of circumferentially spaced vanes extending outwardly from the hub portion to block a portion of the cross-sectional area of the passage. An actuator drives one end of the shaft and alternate baffles are keyed to the shaft so that actuation of the actuator relatively rotates the modular baffles to selectively vary the cross-sectional blockage defined by the baffles.

Abstract: A method of operating a combustor to heat a fuel processor in a fuel cell system, in which the fuel processor generates a hydrogen-rich stream a portion of which is consumed in a fuel cell stack and a portion of which is discharged from the fuel cell stack and supplied to the combustor, and wherein first and second streams are supplied to the combustor, the first stream being a hydrocarbon fuel stream and the second stream consisting of said hydrogen-rich stream, the method comprising the steps of monitoring the temperature of the fuel processor; regulating the quantity of the first stream to the combustor according to the temperature of the fuel processor; and comparing said quantity of said first stream to a predetermined value or range of predetermined values.

Abstract: A method for controlling the power and temperature and fuel source of a combustor in a fuel cell apparatus to supply heat to a fuel processor where the combustor has dual fuel inlet streams including a first fuel stream, and a second fuel stream of anode effluent from the fuel cell and reformate from the fuel processor. In all operating modes, an enthalpy balance is determined by regulating the amount of the first and/or second fuel streams and the quantity of the first air flow stream to support fuel processor power requirements.

Abstract: An electrochemical fuel cell stack comprising an upper end plate assembly; a lower end plate assembly; at least one electrochemical fuel cell assembly interposed between the upper and lower end plate assemblies; and a clamp mechanism operative to compressively clamp the stack. A plurality of screws threaded through threaded bores in the upper end plate at spaced locations in the upper end plate and bearing at their lower ends on an upper face of a distributor plate are selectively tightened to provide a substantially uniform torque in each screw whereby to assure uniform compressive loading across the area of the distributor plate and thereby across the area of the fuel cell assembly.

Abstract: A method and apparatus for controlling the temperature of a combustor in a fuel cell apparatus includes a fast acting air bypass valve connected in parallel with an air inlet to the combustor. A predetermined excess quantity of air is supplied from an air source to a series connected fuel cell and combustor. The predetermined excess quantity of air is provided in a sufficient amount to control the temperature of the combustor during start-up of the fuel processor when the load on the fuel cell is zero and to accommodate any temperature transients during operation of the fuel cell.

Abstract: In one aspect, the invention provides a method of operating a combustor to heat a fuel processor to a desired temperature in a fuel cell system, wherein the fuel processor generates hydrogen (H2) from a hydrocarbon for reaction within a fuel cell to generate electricity. More particularly, the invention provides a method and select system design features which cooperate to provide a start up mode of operation and a smooth transition from start-up of the combustor and fuel processor to a running mode.