International Fuel Cells, LLC

Utc Fuel Cells, LLC

Utc Power Corporation

Thomas F Fuller

Leslie L Van Dine

Douglas J Wheeler

Richard D Breault

Roger R Lesieur

Paul R Margiott

Ned Emidio Cipollini

Deliang Yang

Ryan J Balliet

Jung S Yi

John Donahue

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

A fuel gas reformer assemblage for use in a fuel cell power plant is formed from a composite plate assembly which includes spaced-apart divider plates with columns of individual gas passages. The reformer assemblage is constructed from a series of repeating sub-assemblies, each of which includes a core of separate regenerator/heat exchanger gas passages. The core in each sub-assembly is sandwiched between a pair of reformer gas passage skins, which complete the assembly. Adjacent reformer gas/regenerator/reformer gas passage sub-assemblies in the composite plate assembly are separated from each other by burner gas passages. The regenerator/heat exchanger gas passages and the reformer gas passages in each sub-assembly are connected by gas flow reversing manifolds which form a part of each sub-assembly. The fuel gases flow in one end of the assemblage, through the reformer gas passages, and then reverse their direction of flow in the return manifolds so as to exit the reformer assemblage through the regenerator gas flow passages. The burner gases flow in one end of the reformer assemblage and out the other end. The walls of the burner and reformer gas flow passages are selectively catalyzed after the assemblage has been constructed.

Compact fuel gas reformer assemblage

PEM fuel cell performance losses caused by phenomena occurring during normal cell operation are recovered by periodically reducing the cathode potential to about 0.6 volts or less, and preferably to 0.1 volt or less. Once the cathode potential is reduced to the desired low level, it is maintained at or below that level for a period of time. The lower the potential to which the cathode is brought, the more quickly regeneration will occur. After regeneration, the cell, when returned to normal operation, will operate at a higher performance level.

Method and apparatus for regenerating the performance of a PEM fuel cell

An alcohol and water recovery system for a direct aqueous alcohol fuel cell power plant includes at least one direct aqueous alcohol fuel cell for producing electrical energy, and a direct alcohol and water transfer device for recovering alcohol and water leaving the plant and transferring the recovered alcohol and water back into the plant. The direct alcohol and water transfer device passes a process oxidant stream upstream of the plant in mass transfer relationship with a plant exhaust stream that includes aqueous alcohol fuel and process oxidant fluid streams that have passed through the fuel cell, so that alcohol and water in the plant exhaust stream transfer directly through a mass transfer medium of the device to the process oxidant stream entering the fuel cell. The device includes a separator housing for supporting the transfer medium and for preventing bulk mixing of the streams. An exemplary mass transfer medium such as a liquid water portion of a water saturated polyfluorosulfonic ionomer selectively sorbs fluid substances consisting of polar molecules such as alcohol and/or water molecules from the plant exhaust stream containing polar and non-polar molecules, and desorbs the polar molecules into the process oxidant stream to directly recover and transfer alcohol fuel and water leaving the plant back into the fuel cell, and to thereby also humidify and add heat to the process oxidant stream.

Alcohol and water recovery system for a direct aqueous alcohol fuel cell

During start up, a fuel cell is warmed to operating temperature by introducing a dilute hydrogen/air mixture into the normal process oxidant channels of the fuel cell where it reacts with a noble metal or noble metal alloy catalyst to produce heat at subflame temperatures. In one embodiment, catalyst is provided in a structure between the cathode and the process oxidant channels; if the structure is not sufficiently hydrophobic to allow the hydrogen/fuel mixture to reach it, such structure may be specially produced with hydrophobic regions to assure ice-free passages; in a structure with sufficient hydrophobic regions, only the catalyst need be added. In embodiments with a hydrophobic cathode, no structural modification is required; or a hydrophilic cathode may be provided with hydrophobic regions.

Start up of frozen fuel cell

A proton exchange membrane fuel cell has methanol or ethanol fed into the coolant passages during shut down so as to prevent water trapped therein from freezing in sub-freezing environments. Upon start-up, a controlled amount of air is fed through the cathode reactant flow field so that alcohol diffusing to the cathode catalyst is oxidized, producing heat which will raise the temperature of the fuel cell above freezing, and to a normal operating temperature. A heat exchanger in the coolant water circulating loop may be bypassed during start-up.

Start up of cold fuel cell

A mass transfer composite membrane for use with a fuel cell power plant includes a transfer medium core between opposed, rigid, porous support sheets. An inlet surface of the composite membrane is positioned in contact with an oxidant inlet stream of a fuel cell power plant, and an opposed exhaust surface of the composite membrane is positioned in contact with an exhaust stream exiting the fuel cell power plant to recover mass such as water from the exhaust stream and transfer it into the oxidant inlet stream entering the fuel cell. The transfer medium core may comprise any of a variety of materials for sorbing a fluid substance consisting of polar molecules such as water molecules from a fluid stream consisting of polar and non-polar molecules. A preferred transfer medium core is an ionomeric membrane such as a water saturated polyfluorosulfonic acid ionomer membrane. The porous support sheets may comprise a reinforcing fiber with a thermoset resin, such as a carbon sheet with a phenolic resin, or a glass fiber with an epoxy resin, wherein the sheets are thermoset into a rigid configuration. The mass transfer composite membrane may be a flat or a mounded layer defining protrusions and depressions. A plurality of the mounded layer membranes may be disposed within a frame in mirror-image association wherein protrusions and depressions formed by the mounds of adjacent membranes contact each other to define serpentine passages for the inlet and exhaust streams.

Mass transfer composite membrane for a fuel cell power plant

A mass and heat recovery system for a fuel cell power plant includes at least one fuel cell for producing electrical energy, hydrocarbon fuel processing components for producing a hydrogen rich reducing fluid for the fuel cell, and a direct mass and heat transfer device for recovering mass and heat such as water vapor leaving the plant. The fuel processing components include an auxiliary burner that provides heat to generate steam and a reformer that receives the steam mixed with a hydrocarbon fuel along with a small amount of air and converts the mixture to a hydrogen rich stream appropriate for supplying hydrogen to the anode electrode. The direct mass and heat transfer device passes a process oxidant stream upstream of the plant in mass transfer relationship with a plant exhaust stream that includes both a cathode exhaust stream and an anode exhaust stream wherein the anode exhaust stream has first been burned in the auxiliary burner so that mass and heat such as water vapor in the plant exhaust stream transfer directly through a mass transfer medium of the device to the process oxidant stream entering the plant. The device includes a separator housing for supporting the transfer medium and for preventing bulk mixing of the streams. An exemplary transfer medium such as a liquid water portion of a water saturated polyflourosulfonic ionomer selectively sorbs a fluid substance consisting of polar molecules such as water molecules from a fluid stream containing polar and non-polar molecules.

Growing community of inventors

Glastonbury, CT, United States of America

Thomas F Fuller