PASSIVE AIR BREATHING FUEL CELL SYSTEM WITH SWITCHED FUEL GAS DELIVERY

摘要

A fuel cell system (10) includes a polymer electrolyte fuel cell (11) with a stack of fuel cell units having an internal fuel flow channel extending between a first fuel supply inlet (12) and a second fuel supply inlet (13). A distribution valve (9) is connected by supply lines to the two inlets of the fuel cell and to a source of fuel gas such as hydrogen in a canister under pressure (17). In a first position of the distribution valve, fuel is supplied to the fuel flow channel through the first supply inlet, and in a second position of the valve, fuel is supplied through the second fuel supply inlet. The valve is switched at a selected frequency to provide alternating flow of fuel gas through the fuel flow channel, equalizing the concentration of fuel gas in the fuel flow channel and mixing the water vapor and inert gases within the fuel flow channel to avoid localized concentrations.