AVOIDING COOLANT SLUMP INTO REACTANT FIELDS DURING PEM FUEL CELL SHUTDOWN

摘要

A fuel cell power plant (100) having a stack of fuel cells (102), each having an anode (104), a fuel reactant gas flow field plate (118), a cathode (106), an oxidant reactant gas flow field plate (120), and an electrolyte (101) between the anode and cathode. The stack has coolant channels (131), an air blower (144), air inlet (139a) and outlet (141a) valves, and a cathode recycle loop using either the primary air blower or a cathode recycle blower (135). A shutdown process includes recycling air through the cathodes with only one of an air inlet valve or air exit valve closed, while applying fresh fuel and recycling fuel through the anodes until oxygen is about 4% or less, or average cell voltage is about 0.2 or less, or for predetermined period of time.