Abstract: A fuel cell system operating method in which a temperature of a fuel cell power generator is measured when the fuel cell power generator stops generating power, and it is determined whether the temperature is within a predetermined temperature range, and a reverse current is supplied to the fuel cell power generator upon restart if the temperature was determined to be outside of the predetermined range so as to increase the efficiency of the system after restarting the fuel cell power generator after being exposed to extreme conditions. Subsequently, the reverse current supply to the fuel cell power generator stops and electric energy is generated through an electrochemical reaction between hydrogen and oxygen in the fuel cell power generator.

Abstract: A fuel cell system operating method in which a temperature of a fuel cell power generator is measured when the fuel cell power generator stops generating power, and it is determined whether the temperature is within a predetermined temperature range, and a reverse current is supplied to the fuel cell power generator upon restart if the temperature was determined to be outside of the predetermined range so as to increase the efficiency of the system after restarting the fuel cell power generator after being exposed to extreme conditions. Subsequently, the reverse current supply to the fuel cell power generator stops and electric energy is generated through an electrochemical reaction between hydrogen and oxygen in the fuel cell power generator.

Abstract: A fuel cell system possessing a mixing tank for recovering an unreacted fuel, the mixing tank being capable of effectively condensing a stack emission product without increasing its volume. The mixing tank includes a fuel supply port for supplying a concentrated fuel; a fluid inlet port for supplying a fluid discharged from an external fuel cell stack; a chamber for mixing the concentrated fuel with the fluid discharged from the fuel cell stack; a stack supply port for supplying a mixed fuel in the chamber to the fuel cell stack; and a chamber cooling member for cooling the chamber.