Abstract: An anode reactant recycling system for a fuel cell is disclosed, the system including a hollow main body, a bleed conduit, an injector, a water separator, and a hydrophilic porous media. The anode reactant recycling system for a fuel cell is adapted to minimize a required number of components, eliminate the need for the anode heat exchanger, use a single valve for removal of condensate and reactant byproducts from the anode reactant recycling system, and provide an upstream volume for startup pressurization.

Abstract: An electric insulator for a fuel cell stack with a plurality of fuel cell plates is provided. The electric insulator includes an insulation layer having a water management feature adapted to militate against liquid water contacting the fuel cell plates. Fuel cell stacks having the water management feature are also described.

Abstract: The present invention provides a fuel cell having a membrane electrode assembly disposed between a first diffusion media that has a first set of material characteristics and a second diffusion media that has a second set of material characteristics. The membrane electrode assembly and the first and second diffusion media provide a cell assembly. The cell assembly provides a water transport mechanism that selectively controls water transportation across a thickness of the first and second diffusion media and through the membrane electrode assembly. The first set of material characteristics has at least one material characteristic substantially different from at least one material characteristic of the second set of material characteristics. The selection of the first and second set of material characteristics defines the water transport mechanism for managing hydration of the first and the second diffusion media.

Abstract: A system and method for providing a fuel cell stack purge to remove excess water during system shut-down. A compressor is operated at a shut-down speed to force water out of the cathode flow channels and draw water through the membrane from the anode flow channels so that a desired amount of water is removed from the fuel cell stack without over drying the membrane. The cathode shut-down purge flow can be introduced in the forward or reverse direction. Further, the flow of hydrogen fuel can be directed so that it flows through the anode flow channels in an opposite direction to push water out of an anode outlet manifold into the anode flow channels so that it will also be drawn through the membrane by the cathode airflow. Finally, a brief rehydration step is added after the shut-down purge to achieve the desired water content in the cells.

Abstract: A bipolar plate includes angled facets oriented to form V-shaped projections on the plate edge. Liquid leaving the reactant channels is drawn back into the V-shaped grooves of the projections, leaving no liquid to obstruct the channel exit openings. The bipolar plate includes one portion of the bipolar plate offset from another portion of the bipolar plate so as to expose the reactant channels. The liquid is drawn toward the end portions of the reactant channels by capillary forces, while the gas flows can exit near the beginning of the offset portion. A fuel cell stack includes angled facets that are rotated to lie in the plane of the bipolar plate edges. The edges are chamfered so the channel exit openings of the reactant channels are at the tip portions thereof, thus allowing the liquid to flow away from the channel exit openings and the gas to exit freely.

Abstract: A system and method for correcting an estimation of nitrogen in an anode side of a fuel cell stack. The system includes a fuel cell stack and a pressure sensor for measuring pressure in an anode sub-system. The system also includes a controller configured to control the estimation of nitrogen permeation from the cathode side to the anode side of the stack, where the controller determines if the pressure in the anode sub-system equilibrates with atmospheric pressure in a shorter period of time after shutdown compared to the time necessary for the anode sub-system to reach approximately atmospheric pressure after a previous shutdown or calibrated time value, and corrects the estimation of nitrogen in the anode side of the stack if the pressure equilibrates in a shorter period of time.

Abstract: A flow field plate or bipolar plate for a fuel cell that includes a hydrophilic coating formed on flow field channels extending through a tunnel region between a cell active area and the inlet and outlet manifolds. The flow field plates are an assembly of a cathode side unipolar plate and an anode side unipolar plate. The hydrophilic coating is deposited on the unipolar plates prior to the unipolar plates being assembled into the flow field plate so that line of site deposition processes can be used to coat the flow field channels in the tunnel region. The unipolar plates can be any suitable fuel cell unipolar plates, such as stamped unipolar plates or composite unipolar plates.

Abstract: A fuel cell includes a first catalyst layer and a second catalyst layer. An ion conducting membrane is interposed between the first and second catalyst layers. The ion conducting layer includes a polyolefin support structure and an ion conducting polymer at least partially penetrating the polyolefin support structure. A set of electrically conducting flow field plates are in communication with the first and second catalyst layers.

Abstract: A method for determining the amount of fuel flow from a high pressure gas tank to the anode side of a fuel cell stack through pulsed injector. The anode sub-system pressure is measured just before the injector pulse and just after injector pulse and a difference between the pressures is determined. The difference between the pressures, the volume of the anode sub-system, the ideal gas constant, the anode sub-system temperature, the fuel consumed from the reaction in the fuel cell stack during the injection event and the fuel cross-over through membranes in the fuel cells of the fuel cell stack are used to determine the amount of hydrogen gas injected by the injector.

Abstract: A bipolar plate for use in a proton exchange membrane fuel cell having an electrically conductive polymer coated on at least one region of a surface of the plate in contact with a flow field. The coated region is hydrophobic or hydrophilic as compared to an uncoated region of the surface to prevent liquid accumulation. Electroconductive polymer coatings are applied by electrochemical polymerization.

Abstract: A method of starting a fuel cell stack in subzero conditions that minimizes start times while avoiding cell reversal by using an iterative model to determine the optimal current density time profile for startup.

Abstract: A bipolar plate for a fuel cell is disclosed including a first unipolar plate having an active surface with a plurality of flowfield channels formed therein. The first unipolar plate further includes an inlet header disposed at a first end of the unipolar plate that is in communication with the active surface, and an outlet header disposed at a second end of the unipolar plate having an exhaust opening formed therethrough. A peripheral edge of the exhaust opening is chamfered and is also in communication with the active surface. The chamfered exhaust opening forms a water removal channel in the bipolar plate. A fuel cell stack including the bipolar plate is also disclosed.

Abstract: An anode reactant recycling system for a fuel cell is disclosed, the system including a hollow main body, a bleed conduit, an injector, a water separator, and a hydrophilic porous media. The anode reactant recycling system for a fuel cell is adapted to minimize a required number of components, eliminate the need for the anode heat exchanger, use a single valve for removal of condensate and reactant byproducts from the anode reactant recycling system, and provide an upstream volume for startup pressurization.

Abstract: A pressure fluctuation parameter (for example, a statistical indicator such as a root-mean-square value) from a set of differential pressure measurements between the inlet and the outlet of a fuel cell reactant flow channel carrying vaporized water is used to define flooding onset. Vaporized water in the flow of gas (air) through the flow channels is controlled in response to the parameter. Benefits include efficient operation (i.e., minimized stoichiometry) and effective management of rapid power transients in a fuel cell.

Abstract: A system and method for providing a fuel cell stack purge at fuel cell system shut-down. The method provides a two-stage purge process where the first stage purge uses humidified cathode air to get the fuel cell stack to a known stack hydration level from an unknown stack hydration level at system shut-down. As the stack is purged with the humidified air, the hydration level of the stack decreases asymptotically to the known stack hydration level where the duration of the first stage is set based on the asymptote as a safety margin. Once the known hydration level is achieved, then the second stage purge is performed with dry air to further reduce the stack hydration to a final desired hydration level.

Abstract: A system and method for providing a fuel cell stack purge to remove excess water during system shut-down. A compressor is operated at a shut-down speed to force water out of the cathode flow channels and draw water through the membrane from the anode flow channels so that a desired amount of water is removed from the fuel cell stack without over drying the membrane. The cathode shut-down purge flow can be introduced in the forward or reverse direction. Further, the flow of hydrogen fuel can be directed so that it flows through the anode flow channels in an opposite direction to push water out of an anode outlet manifold into the anode flow channels so that it will also be drawn through the membrane by the cathode airflow. Finally, a brief rehydration step is added after the shut-down purge to achieve the desired water content in the cells.

Abstract: A fuel cell that includes a flow field plate having flow channels, where the flow channels include one enlarged stability flow channel for each set of a predetermined number of smaller flow channels. The stability channel provides a higher volume of flow therethrough, which prevents the accumulation of water at low loads.

Abstract: An electric insulator for a fuel cell stack with a plurality of fuel cell plates is provided. The electric insulator includes an insulation layer having a water management feature adapted to militate against liquid water contacting the fuel cell plates. Fuel cell stacks having the water management feature are also described.

Abstract: A bipolar plate includes angled facets oriented to form V-shaped projections on the plate edge. Liquid leaving the reactant channels is drawn back into the V-shaped grooves of the projections, leaving no liquid to obstruct the channel exit openings. The bipolar plate includes one portion of the bipolar plate offset from another portion of the bipolar plate so as to expose the reactant channels. The liquid is drawn toward the end portions of the reactant channels by capillary forces, while the gas flows can exit near the beginning of the offset portion. A fuel cell stack includes angled facets that are rotated to lie in the plane of the bipolar plate edges. The edges are chamfered so the channel exit openings of the reactant channels are at the tip portions thereof, thus allowing the liquid to flow away from the channel exit openings and the gas to exit freely.

Abstract: A flow field plate or bipolar plate for a fuel cell that includes a hydrophilic coating formed on flow field channels extending through a tunnel region between a cell active area and the inlet and outlet manifolds. The flow field plates are an assembly of a cathode side unipolar plate and an anode side unipolar plate. The hydrophilic coating is deposited on the unipolar plates prior to the unipolar plates being assembled into the flow field plate so that line of site deposition processes can be used to coat the flow field channels in the tunnel region. The unipolar plates can be any suitable fuel cell unipolar plates, such as stamped unipolar plates or composite unipolar plates.