Utc Power Corporation

Utc Fuel Cells, LLC

Ryan J Balliet

Carl Anthony Reiser

Michael L Perry

Robert Mason Darling

Craig E Evans

Jeremy P Meyers

Paul R Margiott

Thomas D Jarvi

Francis R Preli, Jr

Galen W Kulp

Evan Christopher Rege

Tommy Skiba

Timothy W Patterson

Sitaram Ramaswamy

Thomas F Fuller

David D Johnson

Lars M Pedersen

To mitigate bubble blockage in water passageways (), in or near reactant gas flow field plates () of fuel cells (), passageways are configured with (a) intersecting polygons, obtuse angles including triangles, trapezoids, or (b) hydrophobic surfaces (), or (c) differing adjacent channels (), or (d) water permeable layers () adjacent to water channels or hydrophobic/hydrophilic layers ().

Fuel cell coolant bubble control

A method of controlling an amount of liquid in a fuel cell includes increasing the oxygen utilization within the fuel cell to increase heat. The heat reduces the amount of liquid in the fuel cell. A disclosed example method includes decreasing a supply of air to the fuel cell to lower a fuel cell voltage by increasing the oxygen utilization. The example method includes maintaining an essentially electrical current density while decreasing the supply of air.

Controlling an amount of liquid within a fuel cell

To mitigate bubble blockage in water passageways (), in or near reactant gas flow field plates () of fuel cells (), passageways are configured with (a) cross sections having intersecting polygons or other shapes, obtuse angles including triangles and trapezoids, or (b) hydrophobic surfaces (), or (c) differing adjacent channels (), or (d) water permeable layers () adjacent to water channels or hydrophobic/hydrophilic layers (), or (e) diverging channels ().

A fuel cell stack () includes a plurality of fuel cells in which each fuel cell is formed between a pair of conductive, porous, substantially hydrophilic plates () having oxidant reactant gas flow field channels (-) on a first surface and fuel reactant gas flow field channels () on a second surface opposite to the first surface, each &#x2dc;f the plates being separated from a plate adjacent thereto by a unitized electrode assembly () including a cathode electrode (), having a gas diffusion layer (GDL) an anode electrode () having a GDL with catalyst between each GDL and a membrane () disposed therebetween. Above the stack is a condenser (} having tubes () that receive coolant air (} to condense water vapor out of oxidant exhaust in a chamber (). Inter-cell wicking strips () receive condensate and conduct it along the length of the stack to all cells. In-cell wicking strips (G,&#x2dc;a) on one or both surfaces conduct the water from the inter-cell wicking strips downwardly along the entire planform of each cell. Reactant air is provided to an air inlet manifold () through an air inlet conduit () from an air pump ().

Single reactant gas flow field plate PEM fuel cell

The invention is a hydrogen passivation shut down system for a fuel cell power plant (). An anode flow path () is in fluid communication with an anode catalyst () for directing hydrogen fuel to flow adjacent to the anode catalyst (), and a cathode flow path () is in fluid communication with a cathode catalyst () for directing an oxidant to flow adjacent to the cathode catalyst () of a fuel cell (). Hydrogen fuel is permitted to transfer between the anode flow path () and the cathode flow path (). A hydrogen reservoir () is secured in fluid communication with the anode flow path () for receiving and storing hydrogen during fuel cell () operation, and for releasing the hydrogen into the fuel cell () whenever the fuel cell () is shut down.

Hydrogen passivation shut down system for a fuel cell power plant

A fuel cell power plant () has a plurality of fuel cells (,) arranged in a stack (), each fuel cell having porous, at least partially hydrophilic water transport plates () with fuel () and oxidant () reactant gas channels, there being water channels () exchanging water with the water transport plates. On shut down, water is retained in the water channels and water transport plates by means of either a micro vacuum pump (), one or two valves (), a check valve (), capillary force in the water channels to prevent water from entering the reactant channels which, if frozen, could block flow of reactant gas upon startup.

Retaining water in a fuel cell stack for cooling and humidification during frozen startup

A PEM fuel cell power plant includes fuel cells, each of which has a cathode reactant flow field plate which is substantially impermeable to fluids, a water coolant source, and a fluid permeable anode reactant flow field plate adjacent to said water coolant source. The anode reactant flow field plates pass water from the coolant sources into the cells where the water is evaporated to cool the cells. The cathode flow field plates prevent reactant crossover between adjacent cells. By providing a single water permeable plate for each cell in the power plant the amount of water present in the power plant at shut down is limited to a degree which does not require adjunct water purging components to remove water from the plates when the power plant is shut down during freezing ambient conditions. Thus the amount of residual ice in the power plant that forms in the plates during shut down in such freezing conditions will be limited. The power plant can thus be restarted and brought up to full operating power levels quickly due to the reduced amount of ice that must be melted during startup. The power plant is thus well suited for use in powering vehicles.

Non-circulating coolant PEM fuel cell power plant assembly with low thermal mass

Fuel cells () have water passageways () that provide water through reactant gas flow field plates () to cool the fuel cell. The water passageways may be vented to atmosphere (), by a porous plug (), or pumped () with or without removing any water from the passageways. A condenser () receives reactant air exhaust, may have a contiguous reservoir (), may be vertical, (a vehicle radiator, FIG.), may be horizontal, contiguous with the top of the fuel cell stack (, FIG.), or below () the fuel cell stack (). The passageways may be grooves () or may comprise a plane of porous hydrophilic material () contiguous with substantially the entire surface of one or both of the reactant gas flow field plates. Air flow in the condenser may be controlled by shutters (). The condenser may be a heat exchanger () having freeze-proof liquid flowing through a coil () thereof, the amount being controlled by a valve (). A deionizer () may be used.

Fuel cells evaporative reactant gas cooling and operational freeze prevention

A cascaded fuel cell stack () includes a plurality of groups (-) of fuel cells () connected electrically in series by means of conductive separator plates () and current collecting pressure plates (). Each group has an inlet fuel distributing fuel inlet manifold (), a fuel exit manifold () of each group except the last feeding the inlet manifold of each subsequent group. A microcontroller responds to signals from a plurality of voltage sensing devices (-) to cause corresponding switches (-) (a) to connect each group, and all preceding groups in the sequence, to a voltage limiting device (VLD) (), or (b) to connect each group to its own (VLD (-), in response to sensing a predetermined average cell voltage across the corresponding group. When normal operation occurs, the microcontroller connects the main load and disconnects the voltage limiting device () ().

Start up of cascaded fuel cell stack

The invention is a system () and method for determining a gas composition within a fuel cell () of a shut down fuel cell power plant. The system () includes at least one fuel cell (), a sensor circuit () secured in electrical connection with the fuel cell (), wherein the circuit () includes a power source (), a voltage-measuring device (), and a sensor circuit switch (). The circuit () is secured so that the power source () may selectively deliver a pre-determined sensing current to the fuel cell () for a pre-determined sensing duration. The system () selectively admits the reducing fluid into an anode flow field () of the cell () whenever the sensor circuit () senses that a shut down monitoring voltage of the fuel cell () is the same as or exceeds a calibrated sensor voltage limit of the fuel cell ().

System for determining a gas composition within a shut down fuel cell power plant and method of operation

The invention is a hydrogen passivation shut down system for a fuel cell power plant (). An anode flow path () is in fluid communication with an anode catalyst () for directing hydrogen fuel to flow adjacent to the anode catalyst (), and a cathode flow path () is in fluid communication with a cathode catalyst () for directing an oxidant to flow adjacent to the cathode catalyst () of a fuel cell (). Hydrogen fuel is permitted to transfer between the anode flow path () and the cathode flow path (). A hydrogen reservoir () is secured in fluid communication with the anode flow path () for receiving and storing hydrogen during fuel cell () operation, and for releasing the hydrogen into fuel cell () whenever the fuel cell () is shut down.

A fuel cell power plant () having a fuel concentration sensor cell () is disclosed for detecting a concentration of fuel in a fuel cell () of the plant (). A portion of a fuel exhaust stream is directed to flow through the sensor cell () adjacent to a membrane electrode assembly () of the sensor cell (). A power circuit () may or may not deliver an electrical current to the cell (), while changes in voltage across the cell () that are proportional to changes in hydrogen concentrations within the fuel exhaust stream are detected by a detector () which communicates the changes to a controller () for controlling a rate of fuel supply to the fuel cell (). A porous sensor water transport plate () cools, humidifies delivers and removes liquid from the sensor cell ().

Fuel cell power plant having a fuel concentration sensor cell

Performance of a fuel cell stack () is recovered following long term decay by connecting () an auxiliary load () to the fuel cell while shutting off one or more of oxidant inlet valve (), oxidant pressure regulating valve () or oxidant pump (), which all may be achieved with a controller (), to cyclically starve the cathode of oxidant so that it achieves hydrogen potential, e.g., less than 0.1 volts, for on the order of tens of seconds, repetitively, such as at every 10 or 20 seconds, while the auxiliary load remains connected, initially drawing 10 to 100 mASC, for example. Complete rejuvenation is obtained following 1800 or more cycles over a period of five or more hours.

Fuel cell performance recovery by cyclic oxidant starvation

The invention is a start up system and method for a fuel cell power plant () using a purging of the cathode flow field () with a hydrogen rich reducing fluid fuel to minimize corrosion of the cathode electrode (). The method for starting up the shut down fuel cell power plant () includes the steps of: a. purging the cathode flow field () with the reducing fluid fuel; b. then, directing the reducing fluid fuel to flow through an anode flow field (); c. next, terminating flow of the fuel through the cathode flow field () and directing an oxygen containing oxidant to flow through the cathode flow field (); and, d. finally, connecting a primary load () to the fuel cell () so that electrical current flows from the fuel cell () to the primary load ().

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West Hartford, CT, United States of America

Ryan J Balliet