Abstract: The invention provides integrated fuel cell systems and associated operating methods wherein oxidant flow is controlled in response to an oxygen sensor in an exhaust stream of a fuel cell exhaust gas oxidizer, and fuel flow is controlled in response to a temperature measurement associated with the oxidizer.

Abstract: The invention provides a layered design for a fuel cell flow field plate. A flow field plate is formed by mating at least two interlocking layers that form an internal fluid channel between them. The internal fluid channel is generally used to circulate a coolant through the fuel cell. Such plates can be manufactured from a variety of materials including carbon composites and metals, and can be used with a variety of fuel cell configurations, including PEM and other types of fuel cells.

Abstract: Methods and systems for providing a portable source of electrical power are disclosed. These methods and systems include portable power supplies and power synchronizing devices. These methods and systems can be used to provide power to residential and commercial buildings, as well as to, for example, emergency equipment, on a temporary basis. The disclosed portable power supply may include fuel cells or batteries as the source of electrical power. When a fuel cell is used, the portable power supply system typically includes a source of hydrocarbon fuel or hydrogen fuel. The portable power supply is preferably mounted upon a moveable platform, such as a truck or trailer, so that it can be transported to the site where needed. The invention is particularly applicable to providing temporary power when fuel-cell type power supply systems, for example, those including PEM-type fuel cell stacks, require servicing.

Abstract: In one embodiment, an outermost heatable end plate for compressing a fuel cell stack. The outermost heatable end plate includes a body having at least one flow channel formed in the surface of the body through which coolant is passed. In another embodiment, an outermost heatable end plate includes a body and a heating element. The outermost heatable end plates inhibit condensation of water from a humidified reactant passing through an opening in the body of the plate and/or inhibit heat loss from the ends of the fuel cell stack. The opening of the outermost heatable end plate, for example, forms a portion of a manifold for conducting the reactant to the fuel cell stack.

Abstract: A technique that is usable with a fuel cell stack includes providing a fuel flow to the stack, changing the fuel flow and observing a response of at least one cell voltage of the stack to the change in the fuel flow. An efficiency of the stack is regulated based on the observation.

Abstract: Fuel cell systems and methods having relatively long use lifetimes are disclosed. The systems and methods can provide relatively long lifetimes when one or more reactant gas streams is unsaturated with water. The systems and methods can use proton exchange membranes having relatively long use lifetimes.

Abstract: A fuel cell system includes a fuel cell stack, an enclosure housing the fuel cell stack and a blower. The blower is located inside the enclosure and is adapted to draw air from inside the enclosure to produce an air flow through the fuel cell stack and establish a negative pressure inside the enclosure with respect to a region outside of the enclosure.

Abstract: This invention relates to enthalpy wheels and systems containing enthalpy wheels. The enthalpy wheel subasssembly includes a first plate, a cap, a compliance element between the first plate and the cap and a pressure producing element between the fist plate and the cap.

Abstract: A composition is provided that can be used, for example, in a fuel processor for a fuel cell system. The composition includes a first material such as a catalyst, and a second material such as a desiccant. The second material is capable of sorbing and desorbing a heat transfer material such as water, and is present in an amount sufficient to sorb an amount of the heat transfer material sufficient to remove a portion of the heat generated when the first material undergoes an exothermic reaction.

Abstract: Sealant designs for fuel cells, as well as fuel cell systems and methods using such sealant designs, are disclosed.

Abstract: Methods of operating a fuel cell and/or a system containing one or more fuel cells are disclosed. The method includes reversing the flow of one or more reactant gases through one or more flow field plates. The direction of flow can be reversed manually or automatically. The methods can prolong the useful life of the fuel cell or fuel cell system.

Abstract: The invention generally relates to a method and apparatus for collecting condensate from process streams in an integrated fuel cell system. In one aspect, the invention provides a water management subsystem for a fuel cell system. A gas conduit contains a gas at a first pressure. A water tank in the system contains water at a certain level. The water tank has an inlet orifice below the water level. A drain conduit has a first end and a second end. The drain conduit is connected at the first end to the gas conduit, and the drain conduit is connected at the second end to the inlet orifice of the water tank. The water level and the inlet orifice have a vertical height of water between them corresponding to a head pressure greater than the first pressure.

Abstract: A technique that is usable with a fuel cell stack includes coupling the fuel cell stack to a load and determining a power that is consumed by the load. The technique includes detecting a change in the power that is consumed by the load and controlling a fuel flow to the fuel cell stack to control a power output of the fuel cell stack to accommodate the change in the power consumed by the load. The technique also includes delaying the beginning of the controlling in response to the detection of the change in the power that is consumed by the load.

Abstract: A preconditioning technique is disclosed to reduce the time that is needed to incubate membranes of a fuel cell stack. In this manner, the technique includes providing gas flows to an anode region and a cathode region of the fuel cell during a preconditioning time interval without causing electrochemical reactions to occur in the fuel cell. Subsequently, during an incubation time interval, electrochemical reactions occur in the fuel cell to incubate the membranes.

Abstract: The invention generally relates to fuel cell reactant delivery systems and methods for delivering fuel to fuel cell systems, where air or oxygen is injected into a fuel stream containing hydrogen, such that a portion of the hydrogen reacts with the oxygen to form water that humidifies a fuel cell membrane as the fuel stream is passed into the fuel cell. In a preferred embodiment, the invention relates to dead-headed, pure hydrogen PEM fuel cell systems, but the invention is also applicable to other fuel cell system configurations.

Abstract: The invention provides an anode gas diffusion layer for a fuel cell and methods for preparation and use thereof. In particular, a hydrophilic anode gas diffusion layer promotes water transfer through the fuel cell. As an example, in one aspect, the invention provides a fuel cell system, including a fuel cell with an anode gas diffusion layer. The anode gas diffusion layer has a contact angle with water less than 140° (e.g., in some cases less than 120° or less than 100°). In another aspect, the invention provides a gas diffusion layer for a hydrogen electrode of a PEM fuel cell that includes a carbon fiber media having a water contact angle of less than 140°.

Abstract: The invention provides filtration systems and associated methods for filtering a fuel cell reactant stream of particulate and vapor contaminants. In one embodiment, the invention provides a reactant filtration system for a fuel cell, including a first filter having a first inlet and a first outlet, and a second filter having a second inlet and a second outlet. The first filter includes a textile particulate filter, and the second filter includes an activated carbon material. The first and second filters are coupled such that the first inlet is adapted to receive a flow of reactant, which is flowed through the first filter to the first outlet and then to the second inlet, through the second filter and then through the second outlet, which is coupled to an electrode chamber of a fuel cell.

Abstract: The invention relates to systems and associated methods of operating fuel cell systems where the rotational speed of a reactant humidification enthalpy wheel is dynamically controlled according to various process variables. In one embodiment, a method is provided for operating a fuel cell system, including the following steps: (1) rotating a porous desiccant material about a rotational axis; (2) flowing air through the desiccant material in a direction parallel to the rotational axis to a cathode inlet of a fuel cell; (3) flowing cathode exhaust from the fuel cell through the desiccant material; (4) monitoring a process performance variable; (5) detecting a change in a value of the process performance variable; and (6) varying a rotational speed of the desiccant material in response to the detected change in the value of the process performance variable.

Abstract: Fuel cell systems and their methods of operation are disclosed. The fuel cell systems include a water transfer device that can be used to transfer water from one or more exhaust gas streams to an inlet gas stream.

Abstract: In a fuel-cell system, the task of replacing a fuel-cell stack mounted on a base is made easier by a hinge coupling the fuel-cell stack and the base. The hinge enables the stack to be pivoted onto the base so that an aperture on the stack aligns with a corresponding aperture on the base.