Patent ID: 7858252

Claim:
A method of operating a fuel cell system having a fuel cell stack operable to convert an anode reactant flowing through an anode flow path and a cathode reactant flowing through a cathode flow path into an anode effluent, a cathode effluent, and a voltage output, the cathode flow path having a blocking member downstream of the fuel cell stack operable to selectively block all flow in said cathode flow path from exiting the fuel cell stack, the method comprising: (a) operating the fuel cell stack to convert the anode and cathode reactants and produce the voltage output; (b) closing a blocking device in the cathode flow path to block all flow in the cathode flow path from exiting the fuel cell stack; (c) opening the blocking device to reduce a backpressure in the cathode flow path to produce a stream of droplets from liquid water formed in the cathode flow path and to allow flow in the cathode flow path to exit the fuel cell stack; and (d) alternating between performing (b) and (c) while the fuel cell stack is operating, wherein (b) is performed for a first predetermined period of time, (c) is performed for a second predetermined period of time, (d) includes alternating between performing (b) and (c) based upon said first and second predetermined periods of time, and the reaction occurring in the fuel cell stack is not starved of oxygen during the closing step.