Patent ID: 7939209

Claim:
A method for controlling the exhaust gas temperature of a fuel cell system, the fuel cell system including a fuel cell having an anode, a cathode, the fuel cell system further including a fuel supply line for supplying H 2 -containing fuel to the anode, an oxidant supply line for supplying O 2 -containing gas to the cathode, and at least one discharge line for discharging anode gas or cathode gas from the fuel cell, the discharge line being connected by at least one humidifier with the fuel supply line or with the oxidant supply line so that the fuel or the oxidant is humidified with moisture from the exhaust gas, the method comprising the step of: controlling a temperature of the exhaust gas by changing a fuel temperature of the fuel in the fuel supply line or an oxidant temperature of the oxidant in the oxidant supply line, and by transferring heat in the humidifier from the fuel or the oxidant to the exhaust gas, the controlling including cooling the oxidant in the oxidant supply line with a cooling device and a cooling circuit including a control valve by controlling the amount of coolant passing through the cooling device by increasing opening of the control valve or increasing closing of the control valve to adjust the heat transfer in the humidifier from the fuel or the oxidant to the exhaust gas and control the temperature of the exhaust gas.