Abstract: Mechanical stresses of the membrane of a fuel cell can be reduced by virtue of the fact that the supply of feed gas to a gas chamber of the fuel cell takes places, initially, by means of a first pressure increasing speed and then by means of a second pressure increasing speed. The first pressure increasing speed is slower than the second pressure increasing speed. Pressure surges are prevented in the membrane due to the lower pressure increasing speed in the first phase of the gas supply, and as a result, the life span of the membrane is increased.

Abstract: During the operation of a fuel-cell assembly, the latter is supplied with ambient air with the aid of a liquid ring pump. Any foreign matter that is contained in the air is taken up by the service fluid of the liquid ring pump. The charging of the service fluid with foreign matter is controlled. In particular, the service fluid is continuously conducted in an circuit via a purification device.

Abstract: Disclosed is a fuel cell system comprising a fuel cell stack, supplied with a reaction gas on the gas inlet side and comprises at least one flush valve on the gas outlet side on a flush cell. A control device, which controls the actuation of the flush valve as a function of the voltage of the flush cell, is provided, wherein the voltage tap is provided in a region of the flush cell at which the concentration of the reaction gas drops the fastest to a predefined threshold value. Due to the voltage tap in the region where the concentration of the reaction gases drop the fastest to a predefined threshold value, a significantly more sensitive and precise regulation of the flush is possible and voltage dips are effectively prevented in the flush cell, as a result of which the overall risk of corrosion are minimized for the flush cell.

Abstract: Mechanical stresses of the membrane of a fuel cell can be reduced by virtue of the fact that the supply of feed gas to a gas chamber of the fuel cell takes places, initially, by means of a first pressure increasing speed and then by means of a second pressure increasing speed. The first pressure increasing speed is slower than the second pressure increasing speed. Pressure surges are prevented in the membrane due to the lower pressure increasing speed in the first phase of the gas supply, and as a result, the life span of the membrane is increased.

Abstract: A method for starting a mobile fuel cell system, in particular for a vehicle, includes conveying air to be supplied to the system during starting and operation of the system by a motor-powered compressor, in order to ensure a necessary operating pressure and, if required, additional humidifying of the air. A motor drive for the compressor has an electric motor which is supplied from a mobile starter battery during a starting phase. An output voltage of the starter battery is different from an operating voltage at an output of a fuel cell stack of the fuel cell system. A control device is provided between an output of the starter battery or of the fuel cell stack and a motor input. The control device interrupts the starting voltage supplied from the output of the starter battery and switches over to the output voltage of the fuel cell stack when the output operating voltage of the fuel cell stack reaches an adequate level. A fuel cell system is also provided.

Abstract: In a method and an apparatus for monitoring a selected group of fuel cells of a high-temperature fuel cell stack, a change over time in an averaged electrical voltage of the fuel cells of the selected group is ascertained and compared with a reference value that detects at least a change over time in a voltage of other fuel cells. The method permits a reliable detection of the failure of one fuel cell of a stack with simple measures.

Abstract: A fuel cell system having a fuel cell block is operated by compressing an operating agent for the fuel cell block with a liquid ring compressor. After compressing the operating agent, water is separated from the operating agent in an apparatus for water separation. The fuel cell block is cooled with the water and, after the cooling, at least a portion of the water is fed back into the apparatus for water separation. This measure reduces the number of components which form the fuel cell system.