Abstract: A method for locating a fluid leak in a fuel cell stack is disclosed. The method comprises pressurizing a first fluid stream passage with a tracer fluid, introducing a flow fluid to a second fluid stream passage, maintaining a substantially constant flow of the flow fluid through the second fluid stream passage toward an exit point of the fuel cell stack, inserting a probe, adapted to monitor for the presence of the tracer fluid in the flow fluid, into the exit point, moving the probe through the second fluid stream passage and monitoring for the presence of the tracer fluid in the flow fluid at various locations of the second fluid stream passage. An apparatus for locating a fluid leak in a fuel cell stack is also provided.

Abstract: A solid polymer electrolyte fuel cell stack having a plurality of fuel cells, wherein at least one cell of the fuel cell stack has a resistance to corrosion that is greater than a significant portion of the other fuel cells of the stack. In one embodiment, the at least one fuel cell of the fuel cell stack that is more resistant to corrosion is one or both end cells of the stack. Also disclosed is a fuel cell system containing such a stack, as well as methods for reducing degradation of the same during operation.

Abstract: A process for impregnating a porous part is provided. In one embodiment, the process comprises impregnating the part with an impregnant that is not water soluble, and curing the impregnated part in a water bath. In another embodiment, the process comprises impregnating a part with an impregnant that is not water soluble, washing the impregnated part in a washing solution, and then curing the impregnated part in a water bath.

Abstract: A membrane electrode assembly with an improved integrated seal comprises an edge seal having an inboard pad attached to the edge of the electrodes, a flexible coupling adjacent the pad, and a sealing element adjacent the coupling. The sealing element is significantly thicker than the pad, and the flexible coupling isolates the pad from stress experienced in the sealing element. Thus, greater compression can be applied to the sealing element, thereby providing an improved and more reliable seal, without overly compressing and damaging the attached pad.

Abstract: An improved method for embossing expanded graphite sheet material including removing at least a portion of the gas from within the material by exposing the material to a pressure less than atmospheric pressure, and then embossing the material.

Abstract: A fuel cell resistance test system includes a contact head having a plurality of spaced electrical contacts for contacting multiple ones of the fuel cells composing the stack. In one embodiment, a plurality of selectively actuable switches produce a short between respective pairs of adjacent ones of the electrical contacts. A processor opens each of the switches, one at a time in succession, to apply a defined voltage from a voltage source, successively across pairs of adjacent ones of the electrical contacts. A current sensor measures a resulting current and the processor or other computer determines whether a short exists based on the magnitude of the defined voltage and the magnitude of the resulting current. Alternatively, the test system may include a current source and a voltage sensor.

Abstract: A controller in a fuel cell system performs various operating parameter checks at a predefined schedule, including one or more of a stack current check; a stack voltage check; a cell voltage check; a purge cell check; an oxygen concentration check; a hydrogen concentration check; a stack temperature check; an ambient air temperature check; a fuel pressure check; and an airflow rate check; a hydrogen sensor heater check; a battery voltage check; a microcontroller self-check; and/or toggling a watchdog. The frequency of the checks are set relative to achieve an efficient control of the fuel cell system by selectively distributing the load on the microcontroller.

Abstract: An electrical connector for use in a power module includes a first end portion for forming an electrical connection with a substrate, a second end portion, and a compliant portion situated between the first end portion and the second end portion. The compliant portion includes a compressed position and a decompressed position. The first end portion is configured for forming an electrical connection with a substrate if the compliant portion is in the compressed position.

Abstract: A black start operation employs the accumulation of power resulting from a reaction of fuel and ambient oxidant passively seeped or diffused into a fuel cell stack to bootstrap the fuel cell system operation.

Abstract: An operating method increases fuel cell life or durability, particularly that of a solid polymer electrolyte fuel cell. The fuel cell has a mean life expectancy that may be empirically determined. The method comprises the step of reversing the direction of flow of at least one of the fluids supplied to the fuel cell (for example, the fuel and/or oxidant reactants) through its corresponding flow field after a time period of operation of the fuel cell. The time period is less than the mean life expectancy of the cell and has a value that is a substantial part of the mean life expectancy. The flow may be reversed once or several times over the life of the fuel cell. An improved apparatus carries out the method.

Abstract: A flow field plate assembly for an electrochemical fuel cell comprises two flow field plates, each of which has channels formed on an inner surface of the plate. The plates are alignable with and engage each other such that their cooperating inner surfaces form at least one inner coolant fluid channel. The coolant channel has an essentially constant cross-sectional perimeter along its length, which is defined by the perimeters of the channels of the two plates and their difference in width at the cooperating plate surfaces. Additionally, a flow field plate assembly, which comprises a corrugated flow field plate and a staggered flow field plate, is structurally stronger under compressive load during the fuel cell operation.

Abstract: Reactant gas supply streams for solid polymer fuel cells may be heated and humidified using heat generated by the fuel cell and water vapor from the fuel cell exhaust. The heat and water vapor in the oxidant exhaust stream are sufficient to heat and humidify a reactant gas supply stream, preferably the oxidant supply stream. The heating and humidifying can be accomplished by flowing a reactant gas supply stream and a fuel cell exhaust gas stream on opposite sides of a water permeable membrane in a combined heat and humidity exchange apparatus. The method and apparatus are particularly suitable for use with air-cooled fuel cell systems and systems which employ near ambient pressure air as the oxidant gas supply.

Abstract: An aqueous ionomer gel having a high viscosity, particularly a proton conducting ionomer, as well as to related products incorporating such gels. Such aqueous ionomer gels are suitable for suspending catalysts for formation of catalyst inks, which in turn are suitable for screen printing on a variety of surfaces. Representative surfaces are the electrode or membrane surfaces in an electrochemical fuel cell. Methods for making aqueous ionomer gels are also disclosed.

Abstract: Apparatus, systems, and methods for bonding one element of an electrochemical cell or cell stack to another wherein a sealing grove with a complex cross-sectional shape receives and retains a bead of adhesive prior to being assembled. The complex cross-sectional shape has a raised portion sized to receive and retain the bead of adhesive, and at least one depressed portion to receive adhesive displaced from the raised portion during assembly. Embodiments of the invention incorporate raised portions with straight, beveled, curved, and rough surfaces to increase the strength of the bond between the respective elements.

Abstract: In a device for generating electrical power with the fuel cell in a vehicle, a temporary power storage supplies power for a battery start, is charged when the fuel cell is operating, outputs power to connected loads of the fuel cell power system when there is an increased power demand, and absorbs power during braking.

Abstract: Low temperature fuel cells, e.g. solid polymer fuel cells, can operate directly on a fuel comprising dimethyl ether with dimethyl ether being oxidized at the fuel cell anode. Being highly soluble in water, dimethyl ether can be supplied as a liquid aqueous fuel solution. As a fuel, dimethyl ether provides similar power characteristics as methanol but typically with a greater Faradaic efficiency in liquid feed solid polymer fuel cells.

Abstract: A start-up circuit for converters with controller power supply connected at output side. With this start-up circuit, all the control and supporting circuitries are connected at the converter output low voltage side and protected from high input DC voltage. After the converter is started and the controller starts generating normal switching pulses, the start-up circuit may be disabled.

Abstract: Ion-exchange materials comprising a polymeric backbone and a plurality of pendent styrenic or fluoridated styrenic macromonomers covalently bonded thereto, wherein the plurality of pendent styrenic or fluorinated styrenic macromonomers comprise a uniform number of styrenic or fluoridated styrenic monomer repeat units, and wherein predominantly all of the styrenic or fluoridated styrenic monomer repeat units have at least one charged group. Processes for making such material, as well as products related thereto, are also disclosed. In a representative embodiment, the ion-exchange material is utilized as a proton-exchange membrane (PEM) for use in a PEM fuel cell.

Abstract: A method and apparatus increase the temperature of a fuel cell via reactant starvation at one or both electrodes. Reactant starvation at an electrode results in increased internal heat generation under load. Starvation conditions can be prolonged or intermittent and can be obtained, for example, by suitably reducing the supply rate of a reactant or by operating the fuel cell at sufficiently high current density so as to consume reactant faster than it is supplied. The method can allow for some generation of useful power by the fuel cell during start-up. The method is particularly suitable for starting up a solid polymer electrolyte fuel cell from temperatures below 0° C.

Abstract: An electrochemical fuel cell stack with improved reactant man folding and sealing includes a pair of separator plates interposed between adjacent membrane electrode assemblies. Passageways fluidly interconnecting the anodes to a fuel manifold and interconnecting the cathodes to an oxidant manifold are formed between adjoining non-active surfaces of the pairs of separator plates. The passageways extend through one or more ports penetrating the thickness of one of the plates thereby fluidly connecting the manifold to the opposite active surface of that plate, and the contacted electrode. The non-active surfaces of adjoining separator plates in a fuel cell stack cooperate to provide passageways for directing both reactants from respective stack fuel and oxidant supply manifolds to the appropriate electrodes. The fuel and oxidant reactant streams passageways are fluidly isolated from each other, although they both traverse adjoining non-active surfaces of the same pair of plates.