Abstract: A method for controlling the pressure within a fuel cell stack to control the stack relative humidity. In one embodiment, a two-position valve receiving the cathode exhaust is switchable between a fully open and a fully closed position, where the valve is opened when the fuel cell system is operating at a low operation temperature and the valve is closed when the fuel cell system is operating at a high operation temperature. A fixed restriction valve is provided in parallel with the two-position valve so that when the two-position valve is fully closed, the proper amount of pressure is provided at the cathode output. In another embodiment, the two-position valve employs leak paths so that when the two-position valve is in the closed position, the cathode exhaust gas can still flow through.

Abstract: A fuel cell system that employs a two-position valve at the cathode exhaust gas output for controlling the pressure within the fuel cell stack to control the stack relative humidity. In one embodiment, the two-position valve is switchable between a fully open and a fully closed position, where the valve is opened when the fuel cell system is operating at a low operation temperature and the valve is closed when the fuel cell system is operating at a high operation temperature. A fixed restriction valve is provided in parallel with the two-position valve so that when the two-position valve is fully closed, the proper amount of pressure is provided at the cathode output. In another embodiment, the two-position valve employs sized leak paths so that when the two-position valve is in the closed position, the cathode exhaust gas can still flow through.

Abstract: A membrane electrode assembly includes a membrane layer, a cathode or anode catalyst layer adjacent to a surface of the membrane layer, an anode or cathode catalyst layer adjacent to an other surface of the membrane layer, an adhesive layer adjacent to the other surface of the membrane layer, wherein the adhesive layer abuts a surface of the anode or cathode catalyst layer, and a subgasket layer having an edge portion, wherein the subgasket layer is adjacent to a surface of the adhesive layer, wherein the cathode catalyst layer and anode catalyst layer extend along a length of the membrane layer relative to the edge portion of the subgasket layer, wherein the cathode or anode catalyst layer extends a greater length along the length of the membrane layer than the anode or cathode catalyst layer relative to the edge portion of the subgasket layer.

Abstract: A fluid delivery device for an electrochemical conversion assembly. In one embodiment, the electrochemical conversion assembly is a fuel cell system. The device includes one or more fluid-manipulating components combined into a housing to minimize weight, size and complexity. In one form, the device may include a compressor, heat exchanger and a water vapor transfer unit, at least the latter two of which are located within a chamber defined by the housing. A controller can be used to monitor and selectively vary the extent to which at least one of these components modifies properties a fluid (such as air) that can be used as a reactant in the electrochemical conversion assembly. In a particular form, the heat exchanger and water vapor transfer unit can cooperate to promote the hydration of the reactant.

Abstract: A process for fabricating a unitized electrode assembly for a polyelectrolyte membrane is disclosed. The process includes providing a gas diffusion medium and a membrane electrode assembly, printing an adhesive on the gas diffusion medium, locating the gas diffusion medium relative to the membrane electrode assembly and pressing the gas diffusion medium and the adhesive against the membrane electrode assembly.

Abstract: A fuel cell system that employs a two-position valve at the cathode exhaust gas output for controlling the pressure within the fuel cell stack to control the stack relative humidity. In one embodiment, the two-position valve is switchable between a fully open and a fully closed position, where the valve is opened when the fuel cell system is operating at a low operation temperature and the valve is closed when the fuel cell system is operating at a high operation temperature. A fixed restriction valve is provided in parallel with the two-position valve so that when the two-position valve is fully closed, the proper amount of pressure is provided at the cathode output. In another embodiment, the two-position valve employs sized leak paths so that when the two-position valve is in the closed position, the cathode exhaust gas can still flow through.

Abstract: This invention relates to pressurized dispensers such as aerosol containers. The invention provides such dispensers containing a reservoir of an organic substance which dissolves at least 15% of its own weight of propellant at room temperature, the reservoir being capable of releasing the dissolved propellant on dispensing the contents of the container. The organic substance is an extended rubber. Various organic substances can be used to extend the rubber, and various rubbers can be extended. The extenders are generally less expensive than the unextended rubbers, and the extended rubbers can often dissolve as much, or in some cases more propellant than the same weight of unextended rubber. This provides a cost advantage over unextended rubbers. The reservoirs enable the head-space pressure in the dispenser to be maintained substantially constant throughout dispenser life, and foams, for example, of substantially constant density to be obtained.

Abstract: The present invention provides pressurized dispensers comprising a container provided with a valve-controlled outlet and containing a concentrate and a reservoir holding propellant. The reservoir comprises a crystalline organic polymer which is capable of holding propellant therein in such a way that the vapor pressure over the held propellant is reduced below that over the pure propellant, the polymer being capable of holding at least 15% of its own weight of propellant at room temperature, and the reservoir being capable of releasing propellant within the container as the contents of the container are dispensed.