Patent ID: 6391485
Filing Date: 2002-05-21
Classification: H01M,Y02E

Abstract:
A method of purging a fuel cell stack (11) in a fuel cell power plant system (10) during at least one of the two transient operations of shutdown and start-up, the fuel cell stack (11) having a membrane/electrode assembly (MEA)(21,22,23), which MEA includes anode (23) and cathode (22) electrodes on respectively opposite sides of the membrane electrolyte (21), the stack (11) having a fuel reactant flow path (30) on the anode side of the MEA, an oxidant reactant flow path (29) on the cathode side of the MEA, and a coolant flow path (32,31) on at least one of the anode and the cathode sides of the MEA, the fuel reactant flow path (30), the oxidant reactant flow path (29) and the coolant flow path (32,31) each having a respective inlet to (37,39,35) and a respective outlet from (38,40,46) the stack (11), and a fuel reactant supply (42), an oxidant reactant supply (46), and a coolant supply (50) being fed to the fuel reactant inlet (37), the oxidant reactant inlet (39), and the coolant inlet (35), respectively, during normal on load operation of the fuel cell stack (11) in the system (10), the purging method comprising:(a) feeding the coolant supply (50) to at least one of the fuel reactant inlet (37) and the oxidant reactant inlet (39) in the absence of feed of the fuel reactant supply (42) and the oxidant reactant supply (46) to the respective inlets, and (b) causing the coolant to flow in and thereby purge the respective at least one fuel reactant flow path (30) and oxidant reactant flow path (29).