Fuel cell system with fuel gas replacement control at start-up

Abstract From the Canadian patent

The disclosure describes fuel cell systems including a fuel cell stack that generates electricity, an exhaust valve that externally vents a fuel gas from a fuel chamber of the , fuel cell stack and a controller that computes an estimated time to replace an oxidant gas in at , least the fuel chamber with a newly supplied fuel gas wherein at a time of , starting up the fuel cell system the controller maintains the exhaust valve in an open position for the estimated time. , In some embodiments the controller computes the estimated time as a summation of a first time , T1 measured from the fuel cell start-up time to a time when contents of a supply conduit are , replaced with fuel gas a …