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 vehicle includes a fuel-cell system having a fuel cell, a purge valve, and a drain line extending from the purge valve. A controller is programmed to open the purge valve according to a baseline purge routine when the drain line slopes away from the purge valve, and open the purge valve according to an enhanced purge routine when the drain line slopes towards the purge valve.

A fuel cell system comprises: a gas-liquid separator separating exhaust gas of a fuel cell stack into a liquid component and a gas component and storing liquid water of the liquid component; a circulation pipe; a drain pipe discharging the liquid water; and a drain valve opening and closing the drain pipe. In an end scavenging process that is executed when operation of the fuel cell system is finished, the control unit opens the drain valve when a valve opening condition for the drain valve is satisfied. The valve opening condition is set such that an amount of the liquid water stored in the gas-liquid separator at the time the drain valve is opened in the end scavenging process is larger than an amount of the liquid water stored in the gas-liquid separator at the time the drain valve is opened during normal operation of the fuel cell system.

A condensate water drain control system for fuel cells includes a fuel cell stack configured to generate electric power through chemical reaction, a fuel supply line configured to recirculate fuel discharged from the fuel cell stack together with fuel introduced from a fuel supply valve, a water trap located in the fuel supply line, the water trap being configured to collect condensate water discharged from the fuel cell stack, a drain valve configured to discharge the condensate water stored in the water trap to the outside when opened, and a drain controller configured to determine whether the fuel supply valve is controlled such that pressure in the fuel supply line is maintained before the drain valve is opened and to sense discharge of fuel from the fuel supply line through the drain valve upon determining that the pressure is maintained.

A fuel cell stack includes multiple stacked individual cells each having an anode and a cathode, a common fuel inlet duct, a common fuel outlet duct, a common oxidizing agent inlet duct, a common oxidizing agent outlet duct, and at least one microwave source configured to selectively generate microwave radiation into the common fuel outlet duct and/or into the common oxidizing agent outlet duct to manage water contained therein to melt ice and/or expedite evaporation.

The disclosure provides a humidifier control apparatus including a humidifier; a reservoir tank configured to store condensed water discharged from the humidifier; a heating unit configured to apply heat to the reservoir tank; and a drain valve configured to discharge the condensed water stored in the reservoir tank.

A fuel cell system mounted on a vehicle includes a fuel cell, a humidity sensor configured to detect a humidity in a vehicle cabin of the vehicle, a cathode off-gas exhaust passage through which cathode off-gas emitted from the fuel cell is exhausted to outside the vehicle, an introducing port for cathode off-gas, provided in the cathode off-gas exhaust passage, a cathode off-gas introducing unit configured to introduce cathode off-gas emitted from the fuel cell, into the vehicle cabin of the vehicle via the introducing port, and a cathode off-gas introducing amount control unit configured to control an amount of the cathode off-gas introduced into the vehicle cabin of the vehicle in accordance with a humidity in the vehicle cabin of the vehicle, detected by the humidity sensor.

A method for operating a solid oxide fuel cell device is provided, which includes: using waste heat arising during the operation of the solid oxide fuel cell to produce cold by means of a refrigeration machine integrated in a refrigeration circuit for cooling of the exhaust gas at the anode side, condensing the water in the exhaust gas arising at the anode side with the aid of the refrigeration machine by a first water condenser, separating the water by a water separator, compressing the CO.sub.2 exhaust gas flow at the anode side, wherein the cooling power produced by the refrigeration machine is used for cooling of the CO.sub.2 exhaust gas flow, and storing the compressed CO.sub.2 in a CO.sub.2 storage.

A solid oxide fuel cell device and a motor vehicle having a solid oxide fuel cell device are also provided.

A control unit of a fuel cell system opens a second valve at the time of closing a first valve, and maintains the same operating state of a compressor before closing the first valve and after opening the second valve.

A method of operating a fuel cell system includes providing an anode exhaust from a fuel cell stack to a water injector, supplying water to the water injector, and injecting the water from the water injector into the anode exhaust to vaporize the water and generate a humidified anode exhaust.