A method for operating a propulsion system for an aircraft, the propulsion system including a gas turbine engine and a fuel cell assembly, the fuel cell assembly comprising a fuel cell stack having a fuel cell defining an outlet positioned to remove output products from the fuel cell during operation, the method including: executing a startup sequence for the gas turbine engine, wherein executing the startup sequence comprises initiating the startup sequence for the gas turbine engine; executing a startup sequence for the fuel cell assembly concurrently with, or subsequent to, initiating the startup sequence for the gas turbine engine; and operating the fuel cell assembly to provide output products to a combustion section of the gas turbine engine.

The present invention relates to a fuel cell device (1) having a fuel cell (2) which, during operation, emits water as a product of cold combustion; a supply air path (3) leading to the fuel cell (2) for a cathode supply air flow (5), which defines a supply air flow direction (4), the cathode supply air flow coming from water-containing supply air supplied to the fuel cell (2); and an exhaust air path (7)leading away from the fuel cell (2), for a cathode exhaust air flow (9), which defines an exhaust air flow direction (8), the cathode exhaust air flow coming from water-containing exhaust air flowing out of the fuel cell (2). The supply air path (3) and the exhaust air path (7) are routed through a humidifier (10) of the fuel cell device (1), which humidifier communicates fluidically with the supply air and the exhaust air, to humidify the supply air and dehumidifying the exhaust air. The exhaust air path (7) is also routed through a water separator (11) of the fuel cell device (1), which water separator communicates fluidically with the exhaust air, for removing water from the exhaust air and for providing this water as evaporation water. The fuel cell device (1) also has a heat exchanger (12) for cooling the fuel cell (2), which heat exchanger has an evaporative cooler (13) for cooling the heat exchanger (12). It is essential that the evaporative cooler (13) is assigned to the water separator (11) in fluidic communication and that it is supplied with evaporation water by same.

The present invention relates to a fuel cell device (1) having a fuel cell (2) which, during operation, emits water as a product of cold combustion; a supply air path (3) leading to the fuel cell (2) for a cathode supply air flow (5), which defines a supply air flow direction (4), the cathode supply air flow coming from water-containing supply air supplied to the fuel cell (2); and an exhaust air path (7)leading away from the fuel cell (2), for a cathode exhaust air flow (9), which defines an exhaust air flow direction (8), the cathode exhaust air flow coming from water-containing exhaust air flowing out of the fuel cell (2). The supply air path (3) and the exhaust air path (7) are routed through a humidifier (10) of the fuel cell device (1), which humidifier communicates fluidically with the supply air and the exhaust air, to humidify the supply air and dehumidifying the exhaust air. The exhaust air path (7) is also routed through a water separator (11) of the fuel cell device (1), which water separator communicates fluidically with the exhaust air, for removing water from the exhaust air and for providing this water as evaporation water. The fuel cell device (1) also has a heat exchanger (12) for cooling the fuel cell (2), which heat exchanger has an evaporative cooler (13) for cooling the heat exchanger (12). It is essential that the evaporative cooler (13) is assigned to the water separator (11) in fluidic communication and that it is supplied with evaporation water by same.

A fuel tank heat dissipation system for fuel cell (FC) cooling is disclosed. in one example, at least one FC is in thermal communication with an intermediary heat exchanger. A fuel tank is also in fluid communication with the intermediary heat exchanger. A fluid is used to receive heat from the intermediary heat exchanger and flow along a first fluid path to the fuel tank. A nozzle is used to spray the fluid about an interior surface of the fuel tank, where the spray of the fluid about the interior of the fuel tank allows the fluid to dissipate the heat. A second fluid path from the fuel tank to the intermediary heat exchanger, the second fluid path to return the fluid that has dissipated the heat to the intermediary heat exchanger.

The present disclosure relates to a fuel cell system including an air supply line configured to supply air to a fuel cell stack, a bypass line connected to the air supply line and configured to allow the air to flow to a target position, and a bypass valve configured to selectively open or close the bypass line, thereby obtaining an advantageous effect of effectively reducing a hydrogen concentration at the target position.

The present disclosure relates to a fuel cell system including an air supply line configured to supply air to a fuel cell stack, a bypass line connected to the air supply line and configured to allow the air to flow to a target position, and a bypass valve configured to selectively open or close the bypass line, thereby obtaining an advantageous effect of effectively reducing a hydrogen concentration at the target position.

The invention relates to a rotor (4) for an air supply unit (1) of a fuel cell unit, which rotor is to be rotatably mounted in a housing (5) of the air supply unit (1) by means of foil-air bearings (15, 16). According to the invention, at least portions of the rotor (4) are formed of a carbon graphite material or of a synthetic-resin-bonded carbon fiber material or coated therewith. The invention also relates to an air supply unit (1) having a rotor (4) of this type.

The invention relates to a rotor (4) for an air supply unit (1) of a fuel cell unit, which rotor is to be rotatably mounted in a housing (5) of the air supply unit (1) by means of foil-air bearings (15, 16). According to the invention, at least portions of the rotor (4) are formed of a carbon graphite material or of a synthetic-resin-bonded carbon fiber material or coated therewith. The invention also relates to an air supply unit (1) having a rotor (4) of this type.

The invention relates to a heat exchanger system for operating a fuel cell stack, comprising: a first compressor and a second compressor for the cathode gas fed to the fuel cell stack, the second compressor being fluidically downstream of the first compressor; a turbine, which is mechanically coupled to the second compressor and against which the cathode gas discharged from the fuel cell stack flows; a first heat exchanger, which is thermally coupled to the fed cathode gas between the first compressor and the second compressor; a second heat exchanger, which is thermally coupled to the fed cathode gas downstream of the second compressor; a fourth heat exchanger, which is thermally coupled to the discharged cathode gas downstream of the turbine; wherein the fourth heat exchanger is thermally variably coupled to the first heat exchanger and to the second heat exchanger in order to control a heat exchange for cooling the first heat exchanger and the second heat exchanger.

The invention relates to a heat exchanger system for operating a fuel cell stack, comprising: a first compressor and a second compressor for the cathode gas fed to the fuel cell stack, the second compressor being fluidically downstream of the first compressor; a turbine, which is mechanically coupled to the second compressor and against which the cathode gas discharged from the fuel cell stack flows; a first heat exchanger, which is thermally coupled to the fed cathode gas between the first compressor and the second compressor; a second heat exchanger, which is thermally coupled to the fed cathode gas downstream of the second compressor; a fourth heat exchanger, which is thermally coupled to the discharged cathode gas downstream of the turbine; wherein the fourth heat exchanger is thermally variably coupled to the first heat exchanger and to the second heat exchanger in order to control a heat exchange for cooling the first heat exchanger and the second heat exchanger.