Abstract: A fuel cell system includes a polymer electrolyte membrane fuel cell unit having a cooling circuit and an evaporator having at least one evaporation chamber for evaporation of a medium in the fuel cell system and at least one heat-transfer chamber which thermally communicates with the evaporation chamber. The heat-transfer chamber is a part of the cooling circuit of the fuel cell unit.

Abstract: A method and an apparatus produce current values dependent on the position of the accelerator pedal controlling the power of one or more electric drives for moving a mobile device that is energised by a fuel cell. The time required by the drive or drives to respond to a change in the desired current value produced as a function of the position of the accelerator pedal is kept as small as possible by producing a current value—convertible into a desired torque value—which is held continuously at a value sufficient to ensure that the output voltage of the fuel cell just avoids undershooting a critical limit.

Abstract: An arrangement for generating a hydrogen-containing gas from a hydrocarbon-containing medium includes a multi-stage reforming unit that is connected to a multi-stage carbon monoxide removal unit by a heat-conducting separating medium. The stages of the reforming unit, in an ascending order relative to the gas flow direction in the reforming unit, are in a thermal contact with stages of the carbon monoxide removal unit, in a descending order relative to the gas flow direction in the carbon monoxide removal unit.

Abstract: The present invention relates to a circuit arrangement for a composite fuel cell system comprising a plurality of individual fuel cells connected in series, the voltage of the individual fuel cells being monitored, in which case components are present which enable the individual fuel cells to be bridged in the sense of a low-resistance parallel circuit. Furthermore, the invention relates to a method for operating a circuit arrangement of this type, in which case the fuel cells are bridged if the magnitude of their voltage falls below a specific threshold value or if the sign of their voltage has changed relative to normal operation, or alternatively in which case the components are controllable switches which are driven if the composite fuel cell system is intended to be discharged.

Abstract: A gas generator for generating a hydrogen-rich carbon-monoxide-lean gas from a water-fuel mixture by catalytic steam reforming and/or from an oxygen-fuel mixture by partial oxidation includes at least one fuel reservoir vessel; a reforming reactor; a CO shift reactor; a gas purifying unit; and a line to feed water from a water reservoir vessel into the reformate gas stream fed to the CO shift reactor. The water reservoir vessel contains a water-methanol mixture having a mixing ratio effective to ensure adequate frost protection.

Abstract: A fuel cell system includes a gas generation device for the catalytic steam reforming of a steam/fuel mixture and/or for the partial oxidation of an oxygen/fuel mixture for generating a hydrogen-rich medium and a gas cleaning stage for removing carbon monoxide from the product gas of the gas generation device using selective CO oxidation. A principal flow path of the medium is split at least over a certain length into a first and a second parallel flow path and is then brought together again. A flow-diverting means is provided at least in the first flow path in order to open or block the first flow path in a temperature-dependent manner.

Abstract: A fuel cell system has a single-stage or multistage gas generation unit for producing a hydrogen-rich gas from an untreated fuel, a single-stage or multistage gas cleaning unit, at least one fuel cell and a single-stage or multistage exhaust-gas treatment unit for converting the fuel cell exhaust gases as completely as possible. At least two sub-units of the fuel cell system are connected to one another mechanically and in terms of flow by means of a connecting plate.

Abstract: A method and device for insulation monitoring of an electrically insulated DC network by measuring of the insulation resistance using galvanic isolation between a measuring resistor which is connected to ground, and a measuring pulse generator, and a measurement-data acquisition device, which eliminates some of the effect that noise in the DC network would otherwise have on the measurement.

Abstract: A fuel cell system includes (1) a heat exchanger for preheating a fuel/water mixture; (2) an evaporator unit for generating a starting-material gas flow from the preheated fuel/water mixture; (3) a gas generation unit for producing a hydrogen-rich gas containing carbon monoxide from the starting-material gas flow; (4) a gas cleaning unit for selective removal of carbon monoxide from the hydrogen-rich gas; (5) a cooling unit for the gas cleaning unit; and (6) at least one fuel cell comprising an anode chamber through which cleaned, hydrogen-rich gas flows, a cathode chamber through which an oxygen-containing medium flows, and a cooling space through which a coolant flows. The heat exchanger, through which the cleaned, hydrogen-rich gas flows, is arranged downstream of the gas cleaning unit. Alternatively, the heat exchanger is arranged downstream of the cooling space and through which the coolant flows.

Abstract: In a method for improving cold starting of a catalytically active component in gas generation systems for a mobile fuel cell system, a temporary store is arranged directly in the starting-material gas stream. During cold starting, the temporary store stores gaseous constituents from the gaseous starting material, which constituents cause problems when starting, and releases such constituents (which have been stored during the cold-start phase) again as a result of the heating which takes place as operation of the system continues.

Abstract: To carry out a heterogeneously catalysed reaction, a reaction mixture comprising hydrocarbon and water is fed onto a catalyst that is produced by compressing at least one catalyst powder into a highly compressed layer which forms a shaped body. The reaction mixture is pressed through the catalyst layer with a pressure drop.

Abstract: In a fuel cell system having a gas generation system for providing hydrogen from a carbon- and hydrogen-containing medium for a fuel cell unit, means are provided for adjusting pressure in the gas generation system and/or mass flow through the fuel cell unit, upstream of the fuel cell unit. In a transition from a part-load range to a full-load range, the pressure can be at least briefly reduced, and in a transition from a full-load range to a part-load range, the pressure can be at least briefly increased.

Abstract: In a fuel cell system having a fuel cell and a catalytic burner connected downstream thereof, an additional hydrogen-containing medium is fed to the catalytic burner.

Abstract: Methods and apparatus for supplying an oxidant stream, in particular air, to a cathode of a fuel cell, include an oxidant supply device and a return line to recirculate part of the oxidant discharged from the cathode into the oxidant supplied to the cathode. A throttle device is located in the return line, which is connected upstream of the oxidant supply device.

Abstract: In a fuel cell system, and a method of operating a fuel cell system comprising a fuel cell unit and an air supply for providing a fuel for the fuel cell unit, a compressor having a variable internal compression ratio is provided for media delivery in the gas generation system.

Abstract: Insulation monitoring of an electrical network such as a DC network which is electrically insulated with respect to the ground of a device, includes at least two insulation monitoring devices that monitor different network sections, which can be isolated by one or more switches. Non-contacting switches are used to alternatingly connect and isolate respective measuring resistors of the monitoring devices to, and from, ground, as a result of which the insulation monitoring devices can not negatively affect each other's measurements.

Abstract: A vaporizer, a fuel cell system including the vaporizer, and a method of vaporizing fuel in a fuel cell system are disclosed. The fuel cell system includes a fuel reservoir (24) for storing a liquid fuel and a fuel cell (10) for consuming a fuel and generating electricity therefrom. A fuel vaporizer (28) is interposed between the fuel reservoir (24) and the fuel cell (10) for receiving liquid fuel and vaporizing it and delivering it ultimately to the fuel cell (10). The fuel vaporizer (28) includes a heat exchanger which includes a hot fluid inlet (65), a hot fluid outlet (67) and a core (50) interconnecting the inlet (65) and the outlet (68). The core (50) has alternating fuel flow structures (68) and hot fluid structures (69) with the fuel flow structures (68,69) having an inlet (56) and an outlet (58).

Abstract: A device for evaporating liquids includes a porous, thermally conductive evaporation body, which contains a catalyst material on one surface, while the evaporation body is gas-impermeable on the opposite surface. Liquid which is to be evaporated and, if appropriate an additional fuel, can be fed to the evaporation body. The heat of evaporation required is provided by an exothermic reaction of the liquid or with a gaseous oxidizing agent at the catalyst material.

Abstract: An electrical data bus system comprises at least one monitoring device for detecting leakage of a flammable gas within a fuel zone. Pursuant to the method, upon a flammable gas leak within the fuel zone being detected, the flow of electrical current in the fuel zone, via the data bus system or any device connected to the data bus system, is prevented.

Abstract: A device is used to meter a gaseous medium, in particular air, by means of a plurality of metering valves, into a plurality of components of a fuel cell system used in a motor vehicle. All of the metering valves are arranged on a central middle block. The central middle block has at least one inlet opening for the gaseous medium, which is connected, via at least one passage, to in each case one connection point for each of the metering valves.