Abstract: The invention relates to a method for operating a fuel cell system in a mode of reduced power output. The fuel cell system comprises a fuel cell stack (BS) having at least one fuel cell (BZ) with an anode (A), a cathode (K), and a proton exchange membrane, anode and cathode inlets, anode and cathode outlets, and a hydrogen and air supply. In order not to adversely affect the life span of the fuel cell system, the air supply to the cathode (K) is interrupted during the changeover to the mode of reduced power output, and an electric voltage (U) of the fuel cell stack (BS) is reduced by means of a current pulse.

Abstract: In the operation of a fuel cell of a fuel cell system, water contained in the exhaust gas is stored in a water tank. The water tank has means for discharging the water in increments or portions. For example, the water can exit as droplets through the porous floor surface of the water tank, and be carried off by the driving wind while the vehicle is driving; or it can be collected at a wall of a water tank and fed into lines, returning it to the exhaust gas flow as droplets.

Abstract: In a method for controlling a fuel cell system that is designed to react a fuel with an oxidant, the fuel cell system can be switched between an idle condition and an active operating condition. In the idle condition, energy is supplied to an energy consumer, at least in part, from an energy storage device, and the fuel is moved actively within the fuel cell system.

Abstract: The invention relates to a method for operating a fuel cell system in a mode of reduced power output. The fuel cell system comprises a fuel cell stack (BS) having at least one fuel cell (BZ) with an anode (A), a cathode (K), and a proton exchange membrane, anode and cathode inlets, anode and cathode outlets, and a hydrogen and air supply. In order not to adversely affect the life span of the fuel cell system, the air supply to the cathode (K) is interrupted during the changeover to the mode of reduced power output, and an electric voltage (U) of the fuel cell stack (BS) is reduced by means of a current pulse.

Abstract: A method for operating a gas generation device, for example, for a fuel cell system, having at least two gas generation units through which a starting-material stream flows in series. The two gas generating units have a first and second rated power Prated—1, Prated—2 and a first and second predetermined operating temperature Trated—1, Trated—2, and the first gas generation unit has a lower thermal mass than the second gas generation unit. During a starting phase only the first gas generation unit is operated, with a power Pstart—1>Prated—1. After the end of the starting phase at least the second gas generation unit is operated.

Abstract: A system is used for cooling a fuel cell arrangement, particularly a fuel cell arrangement with a gas generating system in a motor vehicle. A coolant circuit for the system is connected to a cooler, a coolant delivery device, a fuel cell and at least another component to be cooled. The coolant circuit has at least two valve devices which are each assigned to the fuel cell and the at least another component to be cooled. By means of the valve devices, a flow rate of the coolant through the fuel cell or the another component to be cooled can be influenced as a function of the temperature in the region associated with the fuel cell or the another component.

Abstract: A system is used for cooling a fuel cell arrangement, particularly a fuel cell arrangement with a gas generating system in a motor vehicle. A coolant circuit for the system is connected to a cooler, a coolant delivery device, a fuel cell and at least another component to be cooled. The coolant circuit has at least two valve devices which are each assigned to the fuel cell and the at least another component to be cooled. By means of the valve devices, a flow rate of the coolant through the fuel cell or the another component to be cooled can be influenced as a function of the temperature in the region associated with the fuel cell or the another component.

Abstract: A method for operating a gas generation device, for example, for a fuel cell system, having at least two gas generation units through which a starting-material stream flows in series. The two gas generating units have a first and second rated power Prated—1, Prated—2 and a first and second predetermined operating temperature Trated—1, Trated—2, and the first gas generation unit has a lower thermal mass than the second gas generation unit. During a starting phase only the first gas generation unit is operated, with a power Pstart—1>Prated—1. After the end of the starting phase at least the second gas generation unit is operated.

Abstract: A fuel cell energy generating system which includes a reformate generating device that contains a hydrocarbon reforming reactor and produces a high-hydrogen reformate, has a fuel cell arrangement to which reformate generated by the reformate generating device can be fed on the inlet side by way of a reformate supply line, having at least one reformate-quality-indicating sensor arranged in the reformate flow path, and having a control unit. A valve is provided in the reformate supply line which can be controlled by the control unit such that it releases or interrupts the feeding of the reformate supplied by the reformate generating device into the fuel cell arrangement as a function of the output signal of the at least one reformate-quality-indicating sensor.