초록 ▼

A fuel cell system (10) having a membrane/electrode assembly (MEA) (16) is provided with the means and technique for quickly inerting the MEA without requiring a nitrogen purge. A first fine pore plate (14) is positioned at an anode side of the MEA and defines a coolant flow field (36) and typically

A fuel cell system (10) having a membrane/electrode assembly (MEA) (16) is provided with the means and technique for quickly inerting the MEA without requiring a nitrogen purge. A first fine pore plate (14) is positioned at an anode side of the MEA and defines a coolant flow field (36) and typically also, a fuel reactant flow field (48). A second fine pore plate (12) is positioned at a cathode side of the MEA and defines a lo coolant flow field (36) and typically also, an oxidant reactant flow field (38). A respective wettable substrate (22,26) is positioned between the MEA and each of the first and second fine pore plates, and is adjacent to the fine pore plates. Various means (50,56,61,60,70,78,66,54,77) drive and control the oxidant flow field, the fuel reactant flow field, and the coolant flow field such that the pressure of the two reactant flow fields is sufficiently greater (.DELTA.P1) than the pressure of the coolant flow field during on load operation to substantially exclude coolant from the reactant flow fields and limit the availability of coolant to the wettable substrates. However, those means drive and control the reactant flow fields and the coolant flow field to such relative pressures (.DELTA.P2) during shutdown and start-up (e. g., small or zero differential near ambient) as to allow coolant to flood the wettable substrates, and in some instances also the reactant flow fields, and thereby protectively inert the system.

대표청구항 ▼

1. A method of inerting a fuel cell system (10) having a membrane/electrode assembly (MEA) (16), which MEA includes anode and cathode electrode catalyst layers (20,24) on respectively opposite sides of the membrane (18), and having a respective support plate (21,25) comprising a respective substrate

1. A method of inerting a fuel cell system (10) having a membrane/electrode assembly (MEA) (16), which MEA includes anode and cathode electrode catalyst layers (20,24) on respectively opposite sides of the membrane (18), and having a respective support plate (21,25) comprising a respective substrate (22,26) at at least one of the anode and cathode catalyst layers (20,24), the method comprising:(a) providing at least one of the substrates (22,26) as a wettable substrate; (b) providing a reactant flow field (38,48) adjacent the respective at least one wettable substrate; (c) providing at least one fine pore plate (12,14) adjacent the respective at least one wettable substrate and including a coolant flow field (36) spaced farther from the membrane (18) relative to the reactant flow field (38,48); (d) operating the reactant flow field (38,48) at a first pressure during on load operation of the fuel cell system (10); (e) operating the coolant flow field (36) at a second pressure during on load operation of the fuel cell system, the second pressure being lower than that of the first pressure to create a first pressure differential (.DELTA.P1) therebetween sufficient to substantially exclude coolant from the reactant flow field (38,48) and to limit availability of coolant to the wettable substrate (22,26); and (f) during fuel cell shutdown, operating the reactant flow field at a third pressure level and operating the coolant flow field at a fourth pressure level, the fourth pressure level being such relative to the third pressure level as to provide a second pressure differential (.DELTA.P2) sufficient to allow the coolant to migrate through the respective fine pore plate (12,14) and flood the respective wettable substrate (26,22) to isolate the respective catalyst layer (24,20) of the MEA from the respective reactant.