Gm Global Technolgoy Operations, Inc.

Stephen Andreas Grot

Mark A Meltser

Rodney Lynn Borup

Kirk Weisbrod

Stanley Gutowski

Jay Kevin Neutzler

Gerald W Fly

Mark F Mathias

David L Wood, Iii

An electrochemical fuel cell stack comprising an upper end plate assembly; a lower end plate assembly; at least one electrochemical fuel cell assembly interposed between the upper and lower end plate assemblies; and a clamp mechanism operative to compressively clamp the stack. A plurality of screws threaded through threaded bores in the upper end plate at spaced locations in the upper end plate and bearing at their lower ends on an upper face of a distributor plate are selectively tightened to provide a substantially uniform torque in each screw whereby to assure uniform compressive loading across the area of the distributor plate and thereby across the area of the fuel cell assembly.

Fuel cell stack compression method and apparatus

A system for controlling the humidity level of a fuel cell is provided. The system includes a fuel cell, a humidifier for humidifying the fuel cell, and a controller for determining the humidity level of the fuel cell and controlling the humidifier in response to the determined humidity level. The resistance of the fuel cell varies as a function of the humidity level of the fuel cell. Thus, in a preferred system, the controller calculates the resistance of the fuel cell via measurements of AC preferred voltage and current components to determine the humidity level of the fuel cell. A method for controlling the humidity level of a fuel cell is also provided. The steps of the method include: determining the humidity level of the fuel cell, and humidifying the fuel cell in response to the determined humidity level.

System and method for controlling the humidity level of a fuel cell

There is provided a multilayer gas distribution structure for use with a membrane electrode assembly of a PEM fuel cell. The layers of the multilayer diffusion structure have selected chemical and physical properties. Together, the layers facilitate transport of reactant gas to the electrode while improving water management.

Composite gas distribution structure for fuel cell

The CO concentration in the H.sub.2 feed stream to a PEM fuel cell stack is monitored by measuring current and/or voltage behavior patterns from a PEM-probe communicating with the reformate feed stream. Pattern recognition software may be used to compare the current and voltage patterns from the PEM-probe to current and voltage telltale outputs determined from a reference cell similar to the PEM-probe and operated under controlled conditions over a wide range of CO concentrations in the H.sub.2 fuel stream. The PEM-probe is intermittently purged of any CO build-up on the anode catalyst (e.g., by (1) flushing the anode with air, (2) short circuiting the PEM-probe, or (3) reverse biasing the PEM-probe) to keep the PEM-probe at peak performance levels.

Method of monitoring CO concentrations in hydrogen feed to a PEM fuel

The CO concentration in the H.sub.2 feed stream to a PEM fuel cell stack is monitored by measuring current and/or voltage behavior patterns from a PEM-probe communicating with the reformate feed stream. Pattern recognition software may be used to compare the current and voltage patterns from the PEM-probe to current and voltage telltale outputs determined from a reference cell similar to the PEM-probe and operated under controlled conditions over a wide range of CO concentrations in the H.sub.2 fuel stream. A CO sensor includes the PEM-probe, an electrical discharge circuit for discharging the PEM-probe to monitor the CO concentration, and an electrical purging circuit to intermittently raise the anode potential of the PEM-probe's anode to at least about 0.8 V (RHE) to electrochemically oxidize any CO adsorbed on the probe's anode catalyst.

Fuel cell CO sensor

Method and apparatus for monitoring the performance of H.sub.2 --O.sub.2 PEM fuel cells. Outputs from a cell/stack voltage monitor and a cathode exhaust gas H.sub.2 sensor are corrected for stack operating conditions, and then compared to predetermined levels of acceptability. If certain unacceptable conditions coexist, an operator is alerted and/or corrective measures are automatically undertaken.

PEM fuel cell monitoring system

A PEM/SPE fuel cell including a membrane-electrode assembly (MEA) having a plurality of oriented filament embedded the face thereof for supporting the MEA and conducting current therefrom to contiguous electrode plates.

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Rochester, NY, United States of America

Stephen Andreas Grot