Gm Global Technolgoy Operations, Inc.

Robert Schaefer

Rainer Pechtold

Sebastian Lienkamp

Thorsten Rohwer

A fuel cell stack that includes cascaded stack stages and tube bundle flow restrictions for providing a cathode input gas to each stage in the stack. The stack includes a first flow pipe for providing cathode gas flow to a first stage of the plurality of stages of the fuel cell stack. The fuel cell stack also includes a second flow pipe that receives a cathode exhaust gas flow from the first stage and fresh cathode gas flow, where the cathode exhaust gas flow and the fresh cathode gas flow are combined and sent to a second stage of the plurality of stages of the fuel cell stack. The tube bundle flow restriction is positioned within the second flow pipe and controls the flow of the cathode gas flow to the second stage, where the flow restriction provides a laminar flow through the control valve to the second stage.

Laminar bypass for cascaded stack

A fuel cell system utilizes at least one flow restricting device to vary the stoichiometric quantity of cathode reactant flowing to two discrete cathode sides of the fuel cell system. The varying of the stoichiometric quantity of cathode reactant can be between two predetermined values. The varying of the stoichiometric quantity can be during a steady state power demand placed on the system and/or during transients in a power demand placed on the system. The airmover that supplies the cathode reactant stream can be operated in a substantially continuous manner during a continuous power demand placed on the fuel cell system.

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Darmstadt, Germany

Robert Schaefer