An air supply system for a fuel cell includes: a fuel cell stack in which multiple unit cells are stacked and that generates electricity through chemical reactions, an air channel to supply incoming air containing oxygen to the fuel cell stack and to transfer air discharged from the fuel cell stack to the outside of the air supply system, and a gas adsorption unit that is disposed on the air channel, positioned near an outlet of the fuel cell stack, and adsorbs oxygen contained in the air introduced into the air channel.

Various embodiments of the present application are directed to methods of measuring a mass flow rate of at least one exhaust gas constituent in an exhaust gas of a fuel cell. In one example embodiment, the method includes the steps of measuring a volumetric flow rate of the exhaust gas; using a gas sensor to determine a concentration of the at least one exhaust gas constituent, and calculating the mass flow rate of the exhaust gas constituent using the volumetric flow rate of the exhaust gas and the determine concentration of the at least one exhaust gas constituent.

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.

To provide a fuel cell system configured to reduce false cross leak judgment. A fuel cell system wherein the controller preliminarily stores a first data group indicating a relationship between the flow rate of the oxidant gas, the opening degree of the bypass valve, and the hydrogen concentration of the oxidant off-gas; and wherein before the controller determines whether or not a cross leak has occurred, the controller varies the hydrogen concentration threshold used for determining whether or not a cross leak has occurred, by comparing the flow rate of the oxidant gas measured by the oxidant gas flow rate sensor and the opening degree of the bypass valve with the first data group.

The invention relates to a detection system (10a; 10b; 10c) for detecting hydrogen (11) in a cavity (12) of a fuel cell vehicle (13), comprising a fuel cell system (15) with a fuel cell housing (16) and a purging air line (17) for purging the fuel cell housing (16) and a hydrogen sensor (14) outside the fuel cell housing (16), wherein the purging air line (17) has a purging air outlet (18) for discharging purging air (19) out of the fuel cell housing (16), wherein the purging air outlet (18) is designed for applying the hydrogen sensor (14) with the purging air from the purging air line (17). The invention also relates to a fuel cell vehicle (13) comprising a detection system (10a; 10b; 10c) according to the invention.

Some embodiments of the disclosure provide a cathode circulation system of a fuel cell connected to a power generation unit of the fuel cell. The cathode circulation system includes a first gas supply tank for providing an inert gas, a second gas supply tank for providing a reaction gas, a mixing tank connected to the first gas supply tank and the second gas supply tank for mixing the inert gas and the reaction gas, a gas-liquid separator connected to the power generation unit, and at least one cathode gas pump provided between the mixing tank and the gas-liquid separator and between the mixing tank and the power generation unit.

A method for shutting down a fuel cell system (2) having at least one fuel cell (3), which fuel cell comprises an anode chamber (10) and a cathode chamber (6), wherein after the shut-down hydrogen remains in the anode chamber (10) of the fuel cell (3) in order to prevent carbon corrosion and to ensure a hydrogen protection time. The invention is characterized in that when the hydrogen in the anode chamber (10) is largely used up directly or after a specified number of subsequent meterings of hydrogen at least into the anode chamber (10), the hydrogen protection time is actively terminated by air being actively admitted into the cathode chamber (6), the fuel cell (3) being actively cooled before air is actively admitted into the cathode chamber (6).

An air supply system for a fuel cell includes: a fuel cell stack in which multiple unit cells are stacked and that generates electricity through chemical reactions, an air channel to supply incoming air containing oxygen to the fuel cell stack and to transfer air discharged from the fuel cell stack to the outside of the air supply system, and a gas adsorption unit that is disposed on the air channel, positioned near an outlet of the fuel cell stack, and adsorbs oxygen contained in the air introduced into the air channel.

A control unit estimates a discharged fuel gas amount, i.e., an amount of fuel gas discharged from the outlet of a cathode flow field, of a fuel exhaust gas introduced from a communication flow path to the inlet of the cathode flow field and then flowing through a cathode. The control unit calculates an oxygen-containing gas amount necessary for dilution at the time of discharge into the atmosphere, from the estimated discharged fuel gas amount, and sets a discharge amount of the air pump, based on the calculated oxygen-containing gas amount.

The invention relates to a device (1) for determining the hydrogen concentration of a fluid in an exhaust gas line (12) of a fuel cell system (100), comprising a sensor (14) which is arranged in a tube section (2), wherein said tube section has an inflow opening (4) and an outflow opening (6). A purge line (40) opens into the tube section (2) between the inflow opening (4) and the H2 sensor (14). A mixing element (8) mixes an exhaust gas flowing through the inflow opening (4) such that different components of the exhaust gas are distributed homogeneously.