Cascaded stack with gas flow recycle in the first stage

Abstract

A fuel cell system including a humidification system is described. The humidification system employs a recycling system that recycles relatively humid gas exhausted from a multistage fuel cell stack, either on the anode and / or cathode side, and sends this relatively humid gas back to be combined with relatively dry supply gas, such as but not limited to hydrogen and / or air. The humidified supply gas mixture is then reintroduced into the first stage of the multistage fuel cell stack. A recirculation device, such as but not limited to a pump and / or an ejector, can be used to aid in moving the humid exhaust gas back through a recycle gas line to be combined with the supply gas.

Description

technical field

[0001] The present invention relates generally to fuel cell systems, and more particularly to new and improved gas flow recirculation systems for fuel cell systems. Background technique

[0002] Fuel cells have been used as power sources in a variety of applications. For example, it has been proposed to use a fuel cell as a power plant in an electric vehicle instead of an internal combustion engine. In a PEM type fuel cell, hydrogen gas is supplied to the anode of the fuel cell and oxygen as an oxidant is supplied to the cathode. A PEM fuel cell includes a membrane electrode assembly (MEA) containing a thin, proton-transporting, non-conductive solid polymer electrolyte membrane with an anode catalyst on one side of the electrolyte membrane and a cathode catalyst on the opposite side. The MEA is sandwiched between a pair of conductive elements, sometimes referred to as gas diffusion media components, which: (1) serve as current collectors for the anode and c...

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