Abstract: In an embodiment a method includes providing a workpiece, attaching a marking to the workpiece such that the marking is integrally bonded to the workpiece, wherein attaching the marking includes applying at least one raw material for the marking, heating the workpiece with the at least one raw material such that the marking is formed from the at least one raw material and performing a surface treatment of the workpiece at least in an area with the marking, wherein performing the surface treatment includes shot peening, sand blasting or material-removing etching against which the marking is resistant to, wherein the marking remains readable on the workpiece at least until after performing the surface treatment, and wherein the marking has, in at least a part of a near ultraviolet, a visible and/or a near-infrared spectral range relative to the workpiece, at least one of a degree of reflection difference, a reflectance difference or an albedo difference of at least 10 percentage points.

Abstract: The invention relates to a fuel cell system comprising a first exothermally operated fuel cell stack and a second non-exothermally operated fuel cell stack, wherein anode waste gas containing water molecules from the first fuel cell stack can be supplied to the second fuel cell stack, and wherein hydrocarbons can be admixed to the anode waste gas by way of a feed line. According to the invention, it is contemplated that the anode waste gas of the first fuel cell stack can be supplied to the second fuel cell stack in an uncooled state. The invention further relates to a method for operating a fuel cell system.

Abstract: The invention relates to a fuel cell system comprising a first exothermally operated fuel cell stack and a second non-exothermally operated fuel cell stack, wherein anode waste gas containing water molecules from the first fuel cell stack can be supplied to the second fuel cell stack, and wherein hydrocarbons can be admixed to the anode waste gas by way of a feed line. According to the invention, it is contemplated that the anode waste gas of the first fuel cell stack can be supplied to the second fuel cell stack in an uncooled state. The invention further relates to a method for operating a fuel cell system.

Abstract: The invention relates to a fuel cell system comprising a reformer for generating a reformate from a fuel and an oxidising agent, a fuel cell for converting the reformate into a depleted reformate and electric energy, and a recirculation conduit for partly returning the depleted reformate to the reformer. In this connection the invention is advantageously characterised in that a delivery device is provided by means of which the fuel as well as the depleted reformate from the recirculation conduit are supplyable to the reformer. The invention further relates to a method for operating such a fuel cell system.

Abstract: The invention relates to a method for testing the leak-tightness of a fuel cell stack comprising the steps of operating the fuel cell stack using defined gas supply rates, a defined modification of at least one gas supply rate, detecting at least one cell or cell group voltage and analysing the variation in time of the at least one cell or cell group voltage.