| 摘要 |
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 (DELTAP1) 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 (DELTAP2) 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.
|
