Abstract: The invention relates to a fuel cells system (10) which comprises at least one heat-generating component (12 to 32) and at least one component (12, 14, 16) that uses process air. The invention is characterized in that ambient air (34) can be supplied to the heat-generating component, said air being heatable by the heat-generating component (12 to 32), and the air heated in said manner being supplied to the component (12, 14, 16) that uses process air. The invention also relates to a method for influencing the thermal balance of the fuel cell system according to the invention.

Abstract: The invention relates to a fuel cell system (10) which comprises a reformer (12) having an oxidation zone (48) to which stored fuel can be supplied by means of a fuel supply device (50) for reaction with an oxidant; and an afterburner (36) having an oxidation zone (60) to which stored fuel can be supplied by means of a fuel supply device (62) for reaction with an oxidant. The invention is characterized in that the fuel supply device (50) of the reformer (12) and the fuel supply device (62) of the afterburner (36) are adapted to supply fuel in such a manner that the fuel supplied by the fuel supply device (50) of the reformer differs from the fuel supplied by the fuel supply device (62) of the afterburner (36) with respect to the type of fuel and/or its state of aggregation and/or the temperature at which it is supplied. The invention also relates to a motor vehicle comprising said fuel cell system and to a method for operating said fuel cell system.

Abstract: The invention relates to a reformer (12) for a fuel cell system (10). Said reformer comprises an oxidation zone (48) to which stored fuel can be supplied by means of a primary fuel supply device (50; 62) for reaction with an oxidant; and a mixing zone (54), arranged downstream of the oxidation zone (48), to which stored fuel can be supplied by means of a secondary fuel supply device (56; 64) for mixing with substances originating from the oxidation zone (48). The invention is characterized in that the primary fuel supply device (50; 62) and the secondary fuel supply device (56; 64) are adapted to supply fuel in such a manner that the fuel supplied by the primary fuel supply device (50; 62) differs from the fuel supplied by the secondary fuel supply device (56; 64) with respect to the type of fuel and/or its state of aggregation and/or the pressure and/or the temperature at which it is supplied.

Abstract: The invention relates to a process for determining the lambda value (?actual) of reformate provided for supply to a fuel cell stack, in which the no-load voltage across at least one fuel cell element is detected and evaluated for determining the lambda value (?actual). In accordance with the invention it is provided for that the at least one fuel cell element is a terminal fuel cell element of the fuel cell stack exclusively provided for sensing, and the voltage provided for at least one consumer can be picked off across the remaining fuel cell elements of the fuel cell stack. The invention relates furthermore to a process for lambda control of a reformer, a device for determining the lambda value, as well as to a system comprising a reformer for reacting at least fuel and air into reformate, and a fuel cell stack which is connected with the reformer for receiving reformate therefrom, the reformer being lambda-controlled.

Abstract: The invention relates to a fuel cell system comprising a reformer and an afterburner each for reacting at least fuel and an oxidant; and a fuel feeder for supplying the reformer and the afterburner with fuel. It is provided for to particular advantage that at least one flow control valve for controlling the fuel supply is included upstream of at least the reformer or the afterburner. The invention relates furthermore to a motor vehicle having one such fuel cell system.