US Patent 7858258 Cascaded fuel cell stack operation with anode gas recirculation

A device and method to regulate humidification in a cascaded fuel cell stack. The cascaded fuel cell stack includes individual fuel cells placed together in multiple groups. A recirculation loop is fluidly coupled to an anode flowpath to permit the recirculation of hydrogen or a related fuel. A controller and one or more sensors and flow manipulation devices cooperate with one another to selectively increase or decrease the flow of reactant in the recirculation loop in order to manage water levels in one or more of the anode, cathode or electrolyte layer disposed between the anode and cathode.