Abstract: The electrochemical performance of an ion-exchange membrane in a fuel cell system may be improved by impregnating therein a perfluoroamine. The amine may be primary, secondary or tertiary. Further, the amine is preferably water insoluble or only slightly water soluble. For example, the amine may be perfluorotriamylamine or perfluorotributylamine. Use of such a membrane system within a fuel cell may allow high or low temperature operation (i.e. at temperatures greater than 100° C. or less than 0° C.) as well as operation at low relative humidity.

Abstract: A method of controlling the temperature within an electrochemical fuel cell stack comprises introducing a reactant fluid stream comprising both a heat transfer liquid and a reactant into a fuel cell assembly such that the reactant fluid stream contacts an electrode. The heat transfer liquid is other than water. Preferably, the method further comprises recirculating heat transfer liquid which is in the reactant exhaust stream, typically via a heat exchanger, and re-introducing it into the fuel cell assembly in the reactant fluid stream. The recirculated heat transfer liquid may be directed to a reservoir which in turn supplies heat transfer liquid to the reactant fluid stream as it is needed. In a further embodiment, the method may comprise using the heat transfer liquid to heat a fuel cell stack to a desired operating temperature rather than cooling the stack.

Abstract: A method is provided for treating electrocatalyst particles and using the treated electrocatalyst for improving performance in an electrochemical fuel cell. The treatment method comprises impregnating pores of the electrocatalyst particles with an impregnant wherein the pores comprise micropores which have an aperture size less than 0.1 micron. The impregnant is preferably ion-conducting and may comprise an organic acid, an inorganic acid, or a polymer. Alternatively, or in addition, the impregnant has an oxygen permeability greater than that of water. The method of impregnating the electrocatalyst particles preferably comprises the steps of contacting the electrocatalyst particles with an impregnant and subjecting the electrocatalyst particles to a vacuum and/or an elevated pressure above atmospheric pressure. The treated electrocatalyst particles are incorporated into an electrochemical fuel cell.

Abstract: Temperature dependent methods can be used to improve the cold start capability of fuel cell electric power generation systems. A method of ceasing operation of an electric power generation system improves the cold start capability and freeze tolerance of a fuel cell stack by reducing the amount of water remaining within the passages of the stack. The method involves purging one or more of the fuel cell stack oxidant and fuel passages at shutdown prior to allowing the fuel cell stack to drop to temperatures below the freezing point of water. Preferably purging at shutdown is conducted at a temperature below the stack operating temperature. Another method, used at start-up, involves directing a coolant fluid stream to the fuel cell stack only after a predetermined temperature above the freezing temperature of water is exceeded. Preferably, after freezing the fuel cell stack is heated to a temperature above its normal operating temperature before operation is commenced.

Abstract: A pump system includes a pump control module and a cassette with a tube including an anti-siphon valve. A valve operates to control free flow situations, and the valve further has a bypass for priming of the system. The valve includes a bypass mechanism including at least one activation member, such as a button, which moves a movable member for disrupting the seal member of the anti-siphon valve. An alternative valve includes a separate bypass pathway around the anti-siphon valve. In this embodiment, operation of the bypass pathway does not disturb or disrupt the seal of the anti-siphon valve. Operation of the alternative bypass pathway is through a bypass mechanism including a button for movement or disruption of a bypass seal. A cap or other holder opens the bypass for each of the valves for gravity priming.

Abstract: A method of ceasing operation of an electric power generation system improves the cold start capability and freeze tolerance of a fuel cell stack by reducing the amount of water remaining within the passages of the stack. The method involves purging one or more of the fuel cell stack oxidant and fuel passages at shutdown prior to allowing the fuel cell stack to drop to temperatures below the freezing point of water. Preferably purging at shutdown is conducted at a temperature below the stack operating temperature.

Abstract: An electrochemical fuel cell is operated with periodic reactant starvation at either or both electrodes. Periodic reactant starvation conditions cause a change in the potential of the starved electrode and may result in the removal of electrocatalyst poisons and in improved fuel cell performance. This technique may have other beneficial effects at the electrodes, including performance improvements due to water management effects or localized heating effects at the starved electrode. In a preferred method, while successive localized portions of a fuel cell electrode are periodically reactant starved, the remainder of the fuel cell electrode remains electrochemically active and saturated with reactant such that the fuel cell is able to continue to generate power.

Abstract: A method of controlling the temperature within an electrochemical fuel cell stack comprises introducing a reactant fluid stream comprising both a heat transfer liquid and a reactant into a fuel cell assembly such that the reactant fluid stream contacts an electrode. The heat transfer liquid is other than water. Preferably, the method further comprises recirculating heat transfer liquid which is in the reactant exhaust stream, typically via a heat exchanger, and re-introducing it into the fuel cell assembly in the reactant fluid stream. The recirculated heat transfer liquid may be directed to a reservoir which in turn supplies heat transfer liquid to the reactant fluid stream as it is needed. In a further embodiment, the method may comprise using the heat transfer liquid to heat a fuel cell stack to a desired operating temperature rather than cooling the stack.

Abstract: An electric power generation system has components that improve the cold start capability and freeze tolerance of a constituent fuel cell stack. The components cooperate to reduce the amount of water remaining within the passages of the stack. The system includes a purge system that is connectable to the oxidant supply, the fuel supply and/or the coolant passages upstream of the stack. When the stack is shut down, the stack is disconnected from an external circuit, and purge fluid is directed by the purge system through the stack before the stack falls below the freezing point of water. In systems where the fuel and/or oxidant streams are humidified prior to their introduction into the stack, a humidifier bypass system may be provided in place of the purge system. The humidifier bypass system directs reactant fluid to the stack in fluid isolation from the humidifier, so that the inlet reactant streams are unhumidified.

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 an increased overvoltage at the electrode and hence 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 improved method reduces fuel cell performance degradation of an electrode comprising porous components. Electrochemical solid polymer electrolyte fuel cells typically have present therein a liquid which expands upon freezing, such as, for example water. The presence of such a liquid within the pores of the electrode components may cause performance degradation of the liquid freezes. The present method comprises employing an impregnant within at least some of the pores of the electrode components. The impregnant inhibits the deterioration of porous fuel cell components caused by expansion of the liquid within the pores when the fuel cell components are subjected to a temperature below the freezing temperature of the liquid. Preferably the impregnant does not expand when changing phases from a liquid to a solid. The impregnant may comprise an organic fluid, an organic acid, an inorganic acid, a polymer or dispersion.

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 an increased overvoltage at the electrode and hence increased internal heat generation under load. Further, starvation techniques may be used to prevent poisoning of electrode catalysts, a potential problem that is aggravated at lower temperatures. 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: A method and apparatus is provided for operating an electrochemical fuel cell with periodic momentary fuel starvation at the anode. It is believed that such momentary periodic fuel starvation conditions cause the anode potential to increase, resulting in the oxidation and removal of electrocatalyst poisons from the anode electrocatalyst and improved fuel cell performance. In a preferred method, while successive localized portions of the fuel cell anode are momentarily periodically fuel starved, the remainder of the fuel cell anode remains electrochemically active and saturated with fuel such that the fuel cell is continually available to generate power.

Abstract: A method is provided for treating electrocatalyst particles and using the treated electrocatalyst for improving performance in an electrochemical fuel cell. The treatment method comprises impregnating pores of the electrocatalyst particles with an impregnant wherein the pores comprise micropores which have an aperture size less than 0.1 micron. The impregnant is preferably ion-conducting and may comprise an organic acid, an inorganic acid, or a polymer. Alternatively, or in addition, the impregnant has an oxygen permeability greater than that of water. The method of impregnating the electrocatalyst particles preferably comprises the steps of contacting the electrocatalyst particles with an impregnant and subjecting the electrocatalyst particles to a vacuum and/or an elevated pressure above atmospheric pressure. The treated electrocatalyst particles are incorporated into an electrochemical fuel cell.