An apparatus for determining state information relating to inertization of a fuel provision system configured to supply a fuel cell unit with fuel and including a vessel for storing fuel and a fuel line between the vessel and/or between a refueling access for refueling the vessel and the fuel cell unit, where the inertization replaces fuel in the fuel line and/or in the fuel cell unit with inert gas. The apparatus includes a device that is configured to cause the fuel cell unit to be supplied with gas from the fuel line while the vessel is closed and/or without fuel being taken from the vessel, to determine measurement information relating to an electric current and/or an electric voltage caused by the fuel cell unit being supplied with gas, and to determine the state information relating to the inertization of the fuel provision system on a basis of the measurement information.

A fuel cell system having a fuel cell using a fuel gas containing a combustible gas and an oxidant gas to generate power includes an exhaust gas route for an exhaust gas from the fuel cell to circulate, an air supplier absorbing air within the fuel cell system and supplying the air to the exhaust gas, an air supply route for the air to circulate, a merging part where the exhaust gas and the air merge, a discharge route discharging a mixed gas composed of the merged exhaust gas and the air to the atmosphere, and a combustible gas detector that detects the concentration of a combustible gas in the mixed gas. With respect to flow of the air circulating in the air supply route and the discharge route, from the upstream side, the air supplier, the merging part, and the combustible gas detector are disposed in this order.

A fuel cell system that has a fuel cell stack is provided. The system includes an electrolyte membrane, and a cathode and an anode that are a pair of electrodes disposed on opposite sides of the electrolyte membrane. A controller applies voltages to the cathode and the anode of the fuel cell stack before hydrogen that operates the fuel cell stack is supplied to the anode. When the voltages are applied to the cathode and the anode, hydrogen that resides in the cathode flows to the anode through the electrolyte membrane to decrease the concentration of the hydrogen in the cathode. The fuel cell system reduces the concentration of hydrogen discharged to the outside of the vehicle by reducing the concentration of hydrogen in the cathode before driving of the fuel cell is initiated.

The invention relates to a method for calibrating a fuel sensor (S) of a fuel cell system (100), wherein the method comprises the following steps: 1) opening a bypass valve (BV) in the bypass line (13) in order to operate the bypass line (13) in the open state; 2) closing shut-off valves (SV1, SV2) in the air supply line (11) and in the exhaust air line (12) in order to conduct all supply air from the air supply line (11) past the at least one fuel cell (101) and introduce it into the exhaust air line (12), 3) carrying out a zero-point calibration of the fuel sensor (S).

There is provided a hydrogen consumption quantity measurement system that, even in a case in which there is a possibility that leakage hydrogen is contained in exhaust gas from a fuel cell or a hydrogen engine, makes it possible to accurately determine a total quantity of hydrogen consumption of the fuel cell without having to modify a vehicle or the like. This hydrogen consumption quantity measurement system measures a hydrogen consumption quantity in a test body, which is formed by a moving body or portion thereof that includes a hydrogen reactor that causes hydrogen to undergo a chemical reaction, and that utilizes energy obtained from this chemical reaction, and includes an oxygen concentration sensor that measures a concentration of oxygen contained in exhaust gas from the test body.

The invention relates to a method for operating a fuel cell system (1), in particular a PEM fuel cell system, in which at least one fuel cell (2) is supplied with a hydrogen-containing anode gas via an anode gas path (3) and anode gas exiting the fuel cell (2) is returned via a recirculation path (4), wherein, in order to reduce a nitrogen content in the anode gas, a flush valve (5) arranged in the recirculation path (4) is opened and the recirculation path (4) is flushed. According to the invention, the hydrogen content of the anode gas is determined using at least one sensor (6) and used as a control variable when controlling the flushing of the recirculation path (4). The invention also relates to a control device (10) for carrying out the method according to the invention.

A mass spectrometry-based method of directly online detecting fuel cell reaction products includes passing a reactant sample (16) through a fuel cell (12) to form reaction products that exit the fuel cell (12) in an output stream (26). The method also includes adding a derivatizing reagent (32) to the output stream (28) to form a derivatized output stream (34), wherein the derivatizing reagent (32) reacts with a potential reaction product to thereby form a derivatized reaction product if the potential reaction product is present. The method further includes directing a charged solvent (44) toward the derivatized output stream (34) to thereby ionize the derivatized output stream (34) and directing the ionized, derivatized output stream (54) to a mass spectrometer (14), the mass spectrometer (14) being configured to detect the derivatized reaction product.

The invention relates to a method to determine a content of a gas component in a gas mixture delivered recirculating through an anode chamber (12) or a cathode chamber (13) of a fuel cell (10), wherein the delivery takes place via a delivery device (26) functioning according to the positive displacement principle. The invention also relates to a fuel cell system (100) configured to execute the method.

According to the invention, the content of the gas component is determined depending on geometric parameters (V, ) and operating parameters (n, U, I) of the delivery device (26), as well as on thermodynamic state variables (p, T) of the gas mixture. The sought target quantity, for example a hydrogen component of an anode gas, can thus be determined in a simple and robust manner from quantities that are already known or measured.

A redox flow battery includes a cell in which a first chamber in which a first electrode serving as an anode during charging is installed and a second chamber in which a second electrode serving as a cathode during charging is installed are divided by a membrane, a first tank that stores a first electrolyte, a first circulation device including a first supply path that connects the first tank and the first chamber and a first recovery path that connects the first chamber and the first tank, a second tank that stores a second electrolyte, a second circulation device including a second supply path that connects the second tank and the second chamber and a second recovery path that connects the second chamber and the second tank, and an adjustment path that supplies gas included in the first tank to the second recovery path.

A reforming element for a molten carbonate fuel cell stack and corresponding methods are provided that can reduce or minimize temperature differences within the fuel cell stack when operating the fuel cell stack with enhanced CO.sub.2 utilization. The reforming element can include at least one surface with a reforming catalyst deposited on the surface. A difference between the minimum and maximum reforming catalyst density and/or activity on a first portion of the at least one surface can be 20% to 75%, with the highest catalyst densities and/or activities being in proximity to the side of the fuel cell stack corresponding to at least one of the anode inlet and the cathode inlet.