Abstract: The invention relates to a fuel cell stack comprising a base plate supporting fuel cells and a cap of an electrically insulating material, particularly of ceramics, for electrically insulating the fuel cells stacked on top of each other partially enveloping the fuel cells stacked on top of each other. According to the invention it is contemplated that a metal cap provided for guiding cathode gas envelops the cap including the fuel cells together with the base plate and that the metal cap is attached to the base plate in a sealed manner. The invention further relates to a method for producing a fuel cell stack.

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 stack comprising a base plate supporting fuel cells and a cap of an electrically insulating material, particularly of ceramics, for electrically insulating the fuel cells stacked on top of each other partially enveloping the fuel cells stacked on top of each other. According to the invention it is contemplated that a metal cap provided for guiding cathode gas envelops the cap including the fuel cells together with the base plate and that the metal cap is attached to the base plate in a sealed manner. The invention further relates to a method for producing a fuel cell stack.

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 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 method for regenerating a reformer fed with a mixture of fuel and an oxidant having a mean air number ?1 in continuous reformer operation, the air number being varied for the purpose of regenerating the reformer. In accordance with the invention it is provided for that regeneration occurs in a shutoff phase of the reformer in that the reformer is operated during several successive time intervals with an air number ?2 higher than in reformer operation (?2>?1). Again in accordance with the invention it may be provided for that regeneration occurs in a starting phase of the reformer in that the reformer is continually operated with an air number increased as compared to reformer operation ?2>?1 until a critical temperature threshold is attained. The invention relates furthermore to a system including a reformer and a controller for implementing a method in accordance with the invention.

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 reformer for a fuel cell system for generating a reformate comprising a plurality of function units for treating the fuel, at least one function unit being adapted to a first type of fuel. In this arrangement the invention is characterized to advantage in that the function unit adapted to the first type of fuel can be releasably coupled to the reformer as a module by means of an interface which is also designed to couple a replacement function unit instead of the function unit adapted to the first type of fuel, the replacement function unit being adapted to a second type of fuel different from the first type of fuel. The invention relates furthermore to a function unit for such a reformer, to a fuel cell system having such a reformer and to a motor vehicle having such a fuel cell system.

Abstract: The invention relates to a fuel cell system including a fuel cell stack (10), an afterburner (12) for combustion of exhaust gas emerging from the fuel cell stack and sited in an exhaust gas conduit of the afterburner a heat exchanger (16) in which cathode feed air (18) supplied to the fuel cell stack (10) can be heated. In accordance with the invention it is provided for that cathode feed air (20) can be supplied to the fuel cell stack (10) without being prior heated in the heat exchanger (16) and that the heat and temperature balance of the fuel cell stack (10) can be tweaked by the overall flow of the cathode feed air supplied as well as by the ratio of the proportions (18, 20) of the cathode feed air as heated in the heat exchanger and as not heated in the heat exchanger. The invention relates furthermore to a method of tweaking the heat and temperature balance of a fuel cell stack.

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.