Ballard Power Systems Corporation

Daimler Ag

Ford Motor Company Limited

Bdf IP Holdings Ltd.

Xcellsis Gmbh

Michael P Sexsmith

Russell H Barton

Stephen A Campbell

Jean St-Pierre

Emerson Richard Gallagher

Herwig Haas

Gerald Hornburg

Eric G Pow

Janusz Blaszczyk

Michael Procter

Donald A Lines

Cara N Startek

Horst Thumm

Andrew J DeSouza

Bill Gray

Kelvin K Fong

Peter J Bach

Mark K Watson

David S Wardrop

Nicholas A Fletcher

Herwig R Haas

Andrew J Desouza

Monika Derflinger

A fuel cell stack comprising a fuel inlet and an oxidant inlet for allowing the supply of a fuel and an oxidant to the fuel cell stack, respectively, and a fuel outlet and an oxidant outlet for allowing the removal of an anode exhaust and a cathode exhaust from the fuel cell stack, respectively, wherein the fuel outlet is fluidly connected to a high frequency purge valve.

System and method of purging fuel cell stacks

An electrochemical fuel cell stack with integrated anode exhaust valves is disclosed, comprising a plurality of fuel cells, each fuel cell having an anode and at least one anode flow field channel, an anode exhaust manifold fluidly connected to the at least one anode flow field channel of each fuel cell, and a means for minimizing fluid backflow from the anode exhaust manifold into the anode flow field channels of the fuel cells. Methods for purging, and reducing fuel cell voltage variations within, the electrochemical fuel cell stack are also disclosed.

Electrochemical fuel cell stack with integrated anode exhaust valves

Improved water distribution can be obtained within the cells of a fuel cell series stack by maintaining a suitable temperature difference between the cathode and anode sides of each cell in the stack during shutdown. A method of shutting down a fuel cell stack having at least two fuel cells stacked in series, each fuel cell having a cathode side and an anode side, the method comprising: stopped the generation of electricity from the stack; allowing the stack to cool over a cooldown period; and maintaining a temperature difference between the cathode side and the anode side of each fuel cell during the cooldown period, wherein the direction of the temperature difference in each fuel cell is the same. The fuel cell stack may comprise coolant channels, Peltier devices and anode and cathode reactant flow fields.

Shutdown methods and designs for fuel cell stacks

Liquid cooled systems having coolant circulation loops must often operate in below freezing conditions. For instance, in various applications certain fuel cell systems must be able to tolerate repeated shutdown and storage in below freezing conditions. Conventional glycol-based coolants typically used for internal combustion engines are generally unsuitable for use in the associated fuel cell cooling subsystems due to the presence of additives and/or inhibitors which are normally included to deal with problems relating to decomposition of the glycol. With additives or inhibitors present, the coolant conductivity can be sufficiently high as to result in electrical shorting or corrosion problems. However, provided the purity of the coolant is maintained, a pure glycol and water coolant mixture may be used as a fuel cell system coolant to obtain suitable antifreeze protection. Adequate purity can be maintained by including an ion exchange resin unit in the cooling subsystem.

Antifreeze cooling subsystem

In a hydrogen gas line where the composition of the gas is primarily hydrogen, impurities present in the gas line will typically reduce the speed of sound. Accordingly, an acoustic sensor can be used in such a hydrogen gas line to indicate when impurities have accumulated in the gas line. In particular, the hydrogen gas line may be in a fuel line for an electrochemical fuel cell system. The sensor may comprise transducers, more particularly piezoelectric transducers, as both sound detectors and/or sound generators. Further, the sensor can measure either the speed or frequency of sound to determine the hydrogen concentration. If the fuel is recirculated back to the anode inlet, such a hydrogen sensor in the anode exhaust may be used to determine when it is beneficial to purge the anode exhaust to the external atmosphere.

Hydrogen concentration sensor for an electrochemical fuel cell

A fuel cell system for powering a work load includes a fuel cell stack and a shunt regulator having a threshold detection; transistorized power switching element, and a dump load. The threshold detection element identifies when an abnormally high voltage rises. The power switching element routes power from the high voltage buss to the dump load. The dump load acts as an electrical energy sink, and may provide dissipated energy to the fuel cell stack in the form of heat. The switching element can also shunt power to the dump load when a digital control signal is set, for example at startup or during cold start conditions.

Fuel cell system shunt regulator method and apparatus

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.

Method for embossing expanded graphite sheet material under reduced pressure

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Vancouver, Canada

Michael P Sexsmith