A concentration reducing apparatus for a fuel cell vehicle includes: a body having an inner flow path through which an exhaust gas containing a target fluid flows in a predetermined discharge direction, in which the body is made of a porous material that allows a selective discharge of the target fluid in order to selectively discharge the target fluid to an outside of the body.

The present disclosure generally relates to monitoring and controlling emissions produced by a fuel cell or fuel cell stack in a fuel cell engine of a vehicle and/or powertrain.

The present disclosure relates to a fuel cell system including a discharge line configured to discharge exhaust gas, which is discharged from a fuel cell stack, to the outside, and a pneumatic branch line having an outlet end connected to the discharge line, and an inlet end connected to a pneumatic supply unit configured to supply air to a pneumatic part of a mobility vehicle, the pneumatic branch line being configured to selectively supply the air from the pneumatic supply unit to the discharge line, thereby effectively reducing a hydrogen concentration in the exhaust gas discharged from the fuel cell stack.

The invention relates to a method for switching off a fuel cell system (100) having a fuel cell stack (10), that has anode chambers (13) and cathode chambers (12), and a cathode supply (20) having a cathode supply path (21) for supplying an oxygenated cathode operating gas into the cathode chambers (12), a compressor (23) arranged in the cathode supply path(21) and a cathode exhaust path (22) for discharging a cathode exhaust gas from the cathode chambers (12).

The method comprises the steps of:

(a) Maintenance of the cathode chambers (12) under excess pressure while preventing a flow of cathode operating gas through the cathode chambers (12) while keeping the cathode operating gas that is present in the cathode chambers (12) oxygen-depleted;

(b) Expansion of the oxygen-depleted cathode operating gas present in the cathode chambers (12) via the cathode supply path (31) [sic] and/or the cathode exhaust path (22), and

(c) Separation of the cathode chambers (12) from the environment.

Disclosed is a method of controlling an air supply system for a fuel cell. The air supply system includes a fuel cell stack, an air channel to supply air to an inlet of the fuel cell stack, a gas adsorption unit disposed on the air channel and configured to adsorb oxygen contained in air introduced into the air channel. In particular, the method includes: determining whether a power generation operation of the fuel cell stack is resumed; when the power generation operation of the fuel cell stack is resumed, controlling a voltage source to apply a voltage to the gas adsorption unit; and supplying air to the fuel cell stack through the air channel in a state in which the voltage is applied to the gas adsorption unit.

A fuel cell system includes: a fuel cell stack including a cathode passage and an anode passage formed thereinside; and a cathode gas supply passage including a first pump discharging cathode gas and connected to an inlet of the cathode passage. The fuel cell system further includes: a cathode off-gas exhaust passage including a back pressure valve and connected to an outlet of the cathode passage; and a circulation passage including a second pump discharging cathode off-gas to circulate cathode off-gas. The fuel cell system circulates cathode off-gas during idling operation to decrease cathodic potential, and increases an opening degree of the back pressure valve to greater than that during idling operation to decrease the cathode back pressure to less than that during idling operation after idling operation is shifted to load operation. This configuration promptly replaces gas in the fuel cell stack.

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.

In various aspects, systems and methods are provided for operating a molten carbonate fuel cell at increased fuel utilization and/or increased CO.sub.2 utilization. This can be accomplished in part by performing an effective amount of an endothermic reaction within the fuel cell stack in an integrated manner. This can allow for a desired temperature differential to be maintained within the fuel cell.

Systems and methods are provided for operating molten carbonate fuel cells to allow for periodic regeneration of the fuel cells while performing elevated CO.sub.2 capture. In some aspects, periodic regeneration can be achieved by shifting the location within the fuel cells where the highest density of alternative ion transport is occurring. Such a shift can result in a new location having a highest density of alternative ion transport, while the previous location can primarily transport carbonate ions. Additionally or alternately, periodic regeneration can be performed by modifying the input flows to the fuel cell and/or relaxing the operating conditions of the fuel cell to reduce or minimize the amount of alternative ion transport.

A hydrogen supply control system for a fuel cell is provided. The system includes a fuel cell stack that generates electricity using supplied hydrogen and air and a recirculation line that supplies hydrogen discharged from an outlet of the fuel cell stack back to an inlet of the fuel cell stack. A purge valve is disposed at an outlet side of the fuel cell stack of the recirculation line and discharges hydrogen in the recirculation line to the outside as the outlet is opened. A recirculation determining processor determines a recirculation state of the recirculation line and a concentration estimator estimates a purge amount for each gas, which is purged by the purge valve, based on the determined recirculation state and estimates a concentration of hydrogen in the recirculation line based on the estimated purge amount for each gas.