Abstract: A device and method are provided to allow the flowpaths in a fuel cell stack to be reconfigured dependent on reactant gas throughput in order to maintain appropriate pressure drop, sufficient velocities, and reactant concentrations of each cell of a fuel cell stack.

Abstract: A method for starting a frozen fuel cell stack includes discontinuing reactant humidification before shutting down the fuel cell stack. The anode and cathode are purged with the dry reactants. The fuel cell stack is soaked at freezing temperatures. During subsequent startup, dry reactants are initially delivered. An outlet temperature of the anode and a current load of the fuel cell stack are measured. The dry reactants are shut off when the temperature of the anode outlet or the current load reach predetermined values. The open circuit voltage potential of the fuel cells is monitored and compared to a first voltage value. When the open circuit voltage exceeds the first value, the fuel cell stack begins supplying current load. The current load of the fuel cell stack is increased or decreased based on a difference between the minimum voltage and a second voltage value.

Abstract: A bipolar plate assembly for a proton exchange membrane fuel cell stack advantageously connects electrically conductive plate surfaces, without the requirement to weld or braze the plate pairs. Each plate has alternating coolant channels and lands formed on an inside facing surface. An electrically conductive layer is deposited over at least the coolant channels and lands. Pairs of plates are aligned having facing electrically conductive layers. A fluid seal is disposed between the inside facing surfaces about a perimeter of the coolant channels. Each plate pair is compressed to form a plurality of electrical bond lines between adjacent lands within the perimeter seal. The perimeter seal prevents stack reactant gas oxygen from contacting and oxidizing the electrically conductive layer. A dielectric coolant is also used to reduce oxidation of the electrically conductive layer.

Abstract: A membrane electrode assembly comprising an ionically conductive member and an electrode, wherein the electrode is a smooth, continuous layer that completely covers and supports the ionically conductive member. The electrode further comprises a central region and a peripheral region, wherein a gradient of electrochemically active material exists between the central region and the peripheral region such that a content of the electrochemically active material is greater in the central region than the peripheral region.

Abstract: A control method for monitoring a fuel cell stack in a fuel cell system in which the actual voltage and actual current from the fuel cell stack are monitored. A preestablished relationship between voltage and current over the operating range of the fuel cell is established. A variance value between the actual measured voltage and the expected voltage magnitude for a given actual measured current is calculated and compared with a predetermined allowable variance. An output is generated if the calculated variance value exceeds the predetermined variance. The predetermined voltage-current for the fuel cell is symbolized as a polarization curve at given operating conditions of the fuel cell. Other polarization curves may be generated and used for fuel cell stack monitoring based on different operating pressures, temperatures, hydrogen quantities.

Abstract: A method and apparatus estimate hydrogen concentration in a reformate stream produced by a fuel processor of a fuel cell. A sensor measures carbon monoxide, carbon dioxide, and water in the reformate stream. A fuel meter controls fuel input to the fuel processor. An air meter controls air input to the fuel processor. A water meter controls water input to the fuel processor. A transport delay estimator recursively estimates transport delay of the fuel processor. A hydrogen estimator associated with the transport delay estimator, the air, water and fuel meters, and the sensor estimates hydrogen concentration in the reformate stream. The hydrogen estimator includes a fuel processor model that is adjusted using the estimated transport delay. The carbon monoxide, the carbon dioxide and the water are measured using a nondispersive infrared (NDIR) sensor.

Abstract: A bipolar plate for use with a fuel cell is provided including an electrically conductive foam as a coolant layer between thin metal foil layers. The thin metal foil layers are provided with serpentine flow field patterns on a surface thereof.

Abstract: A circuit configuration provides a simple device that can be used to monitor the voltage potential between any two points within the fuel cell coolant system without loading (i.e. decreasing) the voltage being monitored. The monitoring circuit include a lamp electrically coupled to the coolant system and arranged in a light-tight package with a photoresistor. When the ionization voltage for the lamp is reached, a fully isolated signal is provided in the form of an abrupt resistance change in the photoresistor. Visual and audible indicators can be coupled to the monitoring circuit to indicate a coolant contamination condition.

Abstract: A fuel processor system capable of circulating fuel processor system gases, such as reformate, anode exhaust, and/or combustor exhaust, through the fuel processor to provide a number of distinct advantages. The fuel processor system having a plurality of fuel cells discharging an H2-containing anode effluent and an O2-containing cathode effluent. A fuel processor is also provided for converting a hydrogen-containing fuel to H2-containing reformate for fueling the plurality of fuel cells. A catalytic combustor is positioned in series downstream from the plurality of fuel cells and a vaporizer reactor is coupled to the catalytic combustor. A bypass passage is finally provided that interconnects an outlet of at least one of the group consisting of the fuel processor, the plurality of fuel cells, the catalytic combustor, and the vaporizer reactor to the inlet of the fuel processor. The bypass passage is operable to circulate a fuel processor system gas to the inlet of the fuel processor.

Abstract: A fuel processor for rapid start and operational control. The fuel processor includes a reformer, a shift reactor, and a preferential oxidation reactor for deriving hydrogen for use in creating electricity in a plurality of H2—O2 fuel cells. A heating and cooling mechanism is coupled to at least the shift reactor for controlling the critical temperature operation of the shift reactor without the need for a separate cooling loop. This heating and cooling mechanism produces or removes thermal energy as a product of the temperature of the combustion of air and fuel. Anode effluent and cathode effluent or air are used to control the temperature output of the heating mechanism. A vaporizer is provided that heats the PrOx reactor to operating temperature.

Abstract: A composite separator plate for use in a fuel cell stack and method of manufacture is provided. The composite separator plate includes a plurality of elongated support members oriented generally parallel to each other and a polymeric body portion formed around the support members. The body portion includes a first surface with a plurality of flow channels and a second surface opposite the first surface. A plurality of electrically conductive fibers are disposed within the polymeric body portion, each fiber extending continuously from the first surface of the polymeric body portion to the second surface of the polymeric body portion in a through plane configuration.

Abstract: A sensor plate for measuring current and/or temperature distribution of an operating fuel cell. The sensor plate has a circuit board interposed between an anode flow field plate and a cathode flow field plate of the fuel cell. A flow field plate is segmented into a plurality of electrically isolated regions without disrupting the flow field of the plate. The circuit board has an array of resistors and/or thermistors mounted to it wherein each resistor and/or thermistor is associated with one of the electrically isolated regions of the segmented plate. The current distribution of the electrically isolated regions of the fuel cell is calculated by using the voltage drop across the resistors and the known resistance values of the resistors mounted to the circuit board.

Abstract: A preferential oxidation reactor is provided including a plurality of reactor sections. The reactor sections are individually optimized for operating at a preferred reaction temperature. In one embodiment, each reactor subsection includes a respective coolant flow for manipulating the operating temperature of the respective subsection. In another embodiment, a first section includes a lower temperature catalyst substrate, a second reactor section includes a higher temperature (i.e. normal) catalyst substrate and a third reactor section includes a lower temperature catalyst substrate. Yet another embodiment includes modifying the catalyst substrates of the respective subsections through the inclusion of promoters. Still another embodiment includes varying a density of the catalyst substrate across the reactor sections. Each of the embodiments enable quick light-off of the reactor, while limiting a reverse water-gas shift reaction.

Abstract: A low humidification and durable fuel cell membrane is provided with water adsorbing material embedded therein in order to adsorb water under wet conditions and provide a reservoir of water to keep the membrane irrigated under dry conditions. A hydrogen oxidation catalyst is provided on the water adsorbing material which will catalyze the reaction of hydrogen and oxygen that are crossing through the membrane and will serve to irrigate the membrane and keep the water adsorbing material full of water. Accordingly, the humidification requirements to a fuel cell stack in an operating system are reduced.

Abstract: An improved fuel processor thermal management system for use with a fuel cell is disclosed. The process includes supplying an air stream and a fuel stream into a auto thermal reactor (ATR) and forming reformate gas therein. Then, preferentially oxidizing the reformate gas and the air stream in the preferential oxidizer reactor (PrOx). The temperature of the preferential oxidizer reaction is controlled with a water stream by vaporizing the water stream to form a first portion of vaporized water. Then, reacting the air stream with the reformate gas exiting the PrOx is reached in a fuel cell to form an anode exhaust stream which is subsequently combined with the air stream to heat the water stream to form a second portion of vaporized water. The first portion of vaporized water and the second portion of vaporized water form a steam fluid.

Abstract: The present invention relates to an electrochemical cell having a terminal collector plate element that conducts electrical current from the stack. The terminal plate has an electrically conductive region and an electrically non-conductive region of the surface. The non-conductive region is coated with a corrosion resistant coating that comprises either a passivation layer, a corrosion-resistant polymeric layer, or both. Optionally, the conductive region of the terminal plate may be protected from oxidation, by coating with an oxidation-resistant metal layer. The oxidation-resistant layer may be further coated with a conductive oxidation-resistant polymeric layer. Other preferred aspects of the present invention include methods of treating the terminal plate to resist corrosion and oxidation while still maintaining electrical conductivity.

Abstract: A fuel cell stack has at least two segments of fuel cells each having reactant gas passages. Each of the cells in each segment is arranged such that the reactant gas passages of each cell are in parallel with each other cell. Flow of fuel cell fluids, normally in a gaseous state on the anode and cathode side of each cell, is in a gravity assisted downward direction. Gravity assisted flow directs water formed in each cell to lower removal points of the stack segments. Each pair of segments is separated by a separator segment having a separator channel, the separator segment forming an integral unit of the stack. Each separator channel redirects the entire flow of each fluid within the stack from the bottom of an upstream segment to the top of a next or downstream segment, without reacting the fluid, controlling relative humidity between stack segments.

Abstract: A venting methodology and system for rapid shutdown of a fuel cell apparatus of the type used in a vehicle propulsion system. H2 and air flows to the fuel cell stack are slowly bypassed to the combustor upon receipt of a rapid shutdown command. The bypass occurs over a period of time (for example one to five seconds) using conveniently-sized bypass valves. Upon receipt of the rapid shutdown command, the anode inlet of the fuel cell stack is instantaneously vented to a remote vent to remove all H2 from the stack. Airflow to the cathode inlet of the fuel cell stack gradually diminishes over the bypass period, and when the airflow bypass is complete the cathode inlet is also instantaneously vented to a remote vent to eliminate pressure differentials across the stack.

Abstract: A fuel processor for a fuel cell includes a thermal start device, a mixing region and a temperature control element. The temperature control element is located between the thermal start device and the mixing region. The temperature control element reduces temperature increase in the mixing region during thermal startup. A flame arrestor is connected to the mixing region. A primary reactor is connected to the flame arrestor. The transient temperature control element has a body defining an inlet and an outlet. A plurality of bores are formed in the body.

Abstract: Recesses are located along an elongated elastomeric member. Electrical contacts are associated with the elastomeric member in registration with the recesses. The elastomeric member expands or compresses along its length to receive one of the closely spaced plates in each of the plurality of recesses and to thereby register the electrical contacts with a corresponding contact point on the plates. The elastomeric strip is confined under compression between two adjacent members which may be parts of two plates or of a single plate. The adjacent members define a recess, including locking protrusions, adapted to resist removal of the connector from within the retention recess unless the elongated elastomeric strip is compressed. An associated method optionally includes allowing the compressed elastomeric strip to push against adjacent members to generate a force which pushes the contact points against the one of the closely spaced plates.