Abstract: In a method for regulating a fuel cell stack (1), a current-voltage characteristic of the fuel cell stack is detected and evaluated to determine an operating point of the fuel cell stack, wherein a current-voltage characteristic of the fuel cell stack (1) is detected at time intervals in operation whose gradient has a minimum, a characteristic value (Rmin) for the minimum of the gradient is respectively determined from the detected current-voltage characteristic and a desired value for the operating point is determined by addition of a predefined offset value (Roffset) to the characteristic value, and wherein the fuel cell stack (1) is regulated by the desired value determined in this manner.

Abstract: A method for the combined controlled regulation of fuel gas-oxygen carriers of a gas operated energy converter plant (15), in particular of a fuel cell plant, is provided in which the mass or volume through flow of the fuel gas (1) and/or of the oxygen carrier (2) is detected in order to regulate the mixing ratio (r) of fuel gas to oxygen carrier. In the method at least two physical parameters of the fuel gas are additionally determined using a micro thermal sensor (3.1, 3.2), for example, the mass flow and/or volume through flow of the fuel gas and the thermal conductivity or thermal capacity of the fuel gas are determined and a desired value for the mixing ratio is determined from the physical parameters which depends on the fuel gas or on the composition of the fuel gas, and which desired value is used for the regulation of the mixing ratio.

Abstract: The method serves for the manufacture of contacts between electrochemically active discs (2) and interconnectors (1) in planar high temperature fuel cells. The interconnectors have air-side and gas-side surface profiles (11, 11?) with contact surfaces (100) located on raised portions (10). A layer consisting of a contacting mixture (22, 22?) is respectively applied onto the electrodes (21, 21?) of the electrochemically active discs or onto the contact surfaces. The surface profiles for the electrodes are brought into contact with the applied layer so that, at a working temperature, the raised portions penetrate into this layer. Connections are formed between the contact surfaces and electrically conductive particles in this way and thus form discrete, homogeneously structured connections between the contact surfaces and the electrodes. Finally the medium embedding the particles is removed under thermal part treatments and the discrete connections are solidified.

Abstract: A method for the combined controlled regulation of fuel gas-oxygen carriers of a gas operated energy converter plant (15), in particular of a fuel cell plant, is provided in which the mass or volume through flow of the fuel gas (1) and/or of the oxygen carrier (2) is detected in order to regulate the mixing ratio (r) of fuel gas to oxygen carrier. In the method at least two physical parameters of the fuel gas are additionally determined using a micro thermal sensor (3.1, 3.2), for example, the mass flow and/or volume through flow of the fuel gas and the thermal conductivity or thermal capacity of the fuel gas are determined and a desired value for the mixing ratio is determined from the physical parameters which depends on the fuel gas or on the composition of the fuel gas, and which desired value is used for the regulation of the mixing ratio.

Abstract: Disclosed is method of operating a fuel cell which can output an electrical maximum power dependent on the operating temperature for a given fuel gas flow, and which exhibits aging in dependence on the operating duration which brings about an increase of the electrical internal resistance with progressive operating duration. In the disclosed method, the starting value (T0) of the operating temperature for a new fuel cell or for a new fuel cell stack is typically smaller than or equal to the operating temperature, at which the electrical maximum power is achieved and the fuel cell or the fuel cell stack is regulated such that the decrease of the output electrical power as a consequence of aging is partly or completely compensated in that the operating temperature (T) of the fuel cell or of the fuel cell stack is increased with progressive aging.

Abstract: The plant with high temperature fuel cells includes a multi component sleeve for a cell stack. Axially directed chambers for an afterburning process are arranged between the periphery of the stack and an outer region of the sleeve. A construction which fixes the chambers includes a corset-like cage, the cross-section of which perpendicular to the stack axis has essentially the shape of a regular polygon. An afterburning chamber is associated with each corner of this polygon. Radial spring forces respectively act from the corners onto the associated chamber and thereby press sealing edges of the chamber onto sealing strips between chamber and stack. The sealing edges form a closed edge of a trough-like space. The trough-like space is connected via a narrow passage with an axial collection passage for exhaust gas. This collecting passage is arranged between the trough-like space and the corner.

Abstract: A fuel cell system (1) having a cell stack (2) for the carrying out of electrochemical reactions is provided which is provided with inlets (3a, 3b) for an oxidant (5) and for fuel gas (6) and with outlets (4a, 4b) for exhaust gases (7a, 7b). The fuel cell system (1) additionally includes an apparatus (10) having a gas-permeable structure which contains a substance which reacts with gaseous chromium species, wherein the apparatus is in communication with at least one of the outlets to direct exhaust gases through the apparatus and to separate chromium species which are carried along by the exhaust gases.

Abstract: In a method for regulating a fuel cell stack (1), a current-voltage characteristic of the fuel cell stack is detected and evaluated to determine an operating point of the fuel cell stack, wherein a current-voltage characteristic of the fuel cell stack (1) is detected at time intervals in operation whose gradient has a minimum, a characteristic value (Rmin) for the minimum of the gradient is respectively determined from the detected current-voltage characteristic and a desired value for the operating point is determined by addition of a predefined offset value (Roffset) to the characteristic value, and wherein the fuel cell stack (1) is regulated by the desired value determined in this manner.

Abstract: The structured body intended for use for an anode (1) in fuel cells, includes a structure formed by macro-pores and an electrode material. The macro-pores form communicating spaces which are produced by using pore forming materials. The electrode material includes skeleton-like or net-like connected structures of particles which are connected by sintering and which form two reticular systems which interengage: a first reticular system made of ceramic material and a second reticular system which contains metals to effect an electrical conductivity. The electrode material has the properties so that, with a multiple change between oxidizing and reducing conditions, substantially no major property changes occur in the ceramic reticular system, and an oxidization or reduction of the metals occurs in the second reticular system.

Abstract: The plant (1) with high-temperature fuel cells (7) includes a clamping device for a cell stack (5) and axially aligned chambers (7) for an after-burning. Clamping bars (60) of the clamping device are disposed between the afterburning chambers. Exhaust gas passages connect the after-burning chambers to a heat exchanger (20a) acting as a heat sink. A clamping element (62) of the clamping device is in heat conducting connection with the heat exchanger. Compression springs (63) are respectively mounted on the clamping bars between an end of the clamping bar and a lug (622) of the clamping element. In this arrangement they exert a clamping force onto the clamping bars. The compression springs are shielded by the clamping element from the cell stack so that, thanks to the heat sink, the compression springs are only exposed to moderate temperature at which the clamping force is maintained.

Abstract: A lambda probe in which a measuring point for oxygen in a sensor is connected via a diffusion gap with a reaction chamber. The reaction chamber drives oxygen along the diffusion gap. A desired oxygen partial pressure is set in the reaction chamber. The pump current, which is proportional to the strength of the stream of oxygen driven along the diffusion gap, can be used as a measurement for the partial pressure of the residual oxygen in the exhaust gas during a normal operating phase. The lambda probe can be operated for test purposes intermittently in a high or low phase, in which the oxygen partial pressure in the reaction chamber is a minimum or maximum value. While changing between the operating phases, by comparing the pump currents with empirical values, conclusions with regard to the ability of the probe to function can be derived.

Abstract: The structured body intended for use for an anode (1) in fuel cells, includes a structure formed by macro-pores and an electrode material. The macro-pores form communicating spaces which are produced by using pore forming materials. The electrode material includes skeleton-like or net-like connected structures of particles which are connected by sintering and which form two reticular systems which interengage: a first reticular system made of ceramic material and a second reticular system which contains metals to effect an electrical conductivity. The electrode material has the properties so that, with a multiple change between oxidizing and reducing conditions, substantially no major property changes occur in the ceramic reticular system, and an oxidization or reduction of the metals occurs in the second reticular system.

Abstract: The structured body intended for use for an anode (1) in fuel cells, includes a structure formed by macro-pores and an electrode material. The macro-pores form communicating spaces which are produced by using pore forming materials. The electrode material includes skeleton-like or net-like connected structures of particles which are connected by sintering and which form two reticular systems which interengage: a first reticular system made of ceramic material and a second reticular system which contains metals to effect an electrical conductivity. The electrode material has the properties so that, with a multiple change between oxidizing and reducing conditions, substantially no major property changes occur in the ceramic reticular system, and an oxidization or reduction of the metals occurs in the second reticular system.

Abstract: A fuel cell system (1) having a cell stack (2) for the carrying out of electrochemical reactions is provided which is provided with inlets (3a, 3b) for an oxidant (5) and for fuel gas (6) and with outlets (4a, 4b) for exhaust gases (7a, 7b). The fuel cell system (1) additionally includes an apparatus (10) having a gas-permeable structure which contains a substance which reacts with gaseous chromium species, wherein the apparatus is in communication with at least one of the outlets to direct exhaust gases through the apparatus and to separate chromium species which are carried along by the exhaust gases.

Abstract: Anode material for a fuel cell which is to be operated at a high temperature above 700° C.

Abstract: Please substitute the following version of the Abstract, with changes shown by strikethrough (for deletions) or underlining (for added matter). The heat exchanger (I) is provided for a heating system with integrated fuel cells (Z) for the production of electricity and with an additional burner (B). Electrical and thermal energy (E, Q) can be produced in this heating system from a gaseous fuel or from a fuel brought into the gas form by means of the fuel cells, and/or thermal energy (Q) can be produced by means of the additional burner. One part of the thermal energy present in the form of hot exhaust gases can be transferred in the heat exchanger to a liquid heat transfer medium, in particular water or an oil. The heat transfer medium is provided for heat transport for the purpose of room heating and/or process water heating. The heat exchanger forms a compact unit which is also made of a material of good thermal conductivity.

Abstract: The porous, gas permeable layer substructure (5; 5a, 5b) for a thin, gas tight layer (89) can in particular be used as a functional component in high temperature fuel cells (8). This layer substructure has a smooth surface (50a) which is suitable for an application of the gas tight layer or a multi-layer system including the gas tight layer, with the application being carried out by means of a screen printing method or other coating methods. The smooth surface is formed by a compacted edge zone (50). The edge zone and a carrier structure (51) adjacent to this are made from sinterable particles of a uniform substance mixture. The porosity of the carrier structure is greater than 30 volume percent, preferably greater than 40 volume percent. The pore size of the edge zone is smaller than 10 ?m, preferably smaller than 3 ?m.

Abstract: The plant (1) with high-temperature fuel cells (7) includes a clamping device for a cell stack (5) and axially aligned chambers (7) for an after-burning. Clamping bars (60) of the clamping device are disposed between the afterburning chambers. Exhaust gas passages connect the after-burning chambers to a heat exchanger (20a) acting as a heat sink. A clamping element (62) of the clamping device is in heat conducting connection with the heat exchanger. Compression springs (63) are respectively mounted on the clamping bars between an end of the clamping bar and a lug (622) of the clamping element. In this arrangement they exert a clamping force onto the clamping bars. The compression springs are shielded by the clamping element from the cell stack so that, thanks to the heat sink, the compression springs are only exposed to moderate temperature at which the clamping force is maintained.

Abstract: A lambda probe (1) is used with the measuring apparatus for monitoring residual oxygen in an exhaust gas, in which a measuring point for oxygen in a sensor (2) is connected via a diffusion gap (22) with a reaction chamber (24). During operation of the probe the reaction chamber drives a stream of oxygen IO2 along the diffusion gap by means of a controllably adjustable oxygen partial pressure pi. By means of an electro-chemical, oxygen ion pump driven by an electrical pump current Ip, an oxygen partial pressure pi predetermined as a desired value is set in the reaction chamber. In this arrangement the pump current, the strength of which is proportional to the strength of the stream of oxygen driven along the diffusion gap, can be used as a measurement parameter for the partial pressure pm of the residual oxygen in the exhaust gas or its concentration. The residual oxygen can be monitored during a normal operating phase, the phase N.

Abstract: The method serves for the manufacture of contacts between electrochemically active discs (2) and interconnectors (1) in planar high temperature fuel cells. The interconnectors have air-side and gas-side surface profiles (11, 11?) with contact surfaces (100) located on raised portions (10). The raised portions of each surface profile having the contact surfaces approximately span a plane (12). In this arrangement deviations (?) lie within a predetermined tolerance. In this method a layer consisting of a contacting mixture (22, 22? is respectively applied onto the electrodes (21, 21?) of the electrochemically active discs or onto the contact surfaces. The contacting mixture contains electrically conductive particles and a medium embedding the particles. The surface profiles for the electrodes are brought into contact with the applied layer so that, at a working temperature, the raised portions penetrate into this layer.