Patent ID: 8492039

Claim:
A fuel cell system comprising: a first sensor installed inside a fuel cell stack of the fuel cell system, the first sensor detecting and providing a temperature of the fuel cell stack; a second sensor detecting and providing a temperature of reformate in a heat exchanger, the reformate generated in a fuel reformer and being supplied to the fuel cell stack through the heat exchanger; and a controller coupled to the first sensor and the second sensor, the controller comparing the temperature of the fuel cell stack detected by the first sensor with the temperature of the reformate in the heat exchanger detected by the second sensor, controlling the temperature of the reformate in the heat exchanger to be lower than the temperature of the fuel cell stack during a starting time of the fuel cell system, wherein the controlling the temperature of the reformate comprises setting the temperature of the reformate in the heat exchanger to maintain relative humidity of the reformate in the heat exchanger to be in a range of 90% to 50% based on the temperature of the fuel cell stack, and wherein the actions performed by the controller are responsive to operation control signals generated by a programmed operation routine in the controller.