A fuel cell unit includes: a first case housing a fuel cell stack; a second case housing a power converter; an adapter fixing the first and second cases together; and a conductive member connecting between the fuel cell stack and the power converter. A first flange portion, surrounding a first opening portion, of the first case and a second flange portion, surrounding a second opening portion, of the second case are different in at least one of shape and size. The adapter includes: a third flange portion corresponding to the first flange portion; a fourth flange portion corresponding to the second flange portion; a surrounding wall portion continuous from the third flange portion to the fourth flange portion to define an internal space communicating with openings inside the third and fourth flange portions; and a partition wall portion between the first opening portion and the second opening portion.

A hydrogen leakage detection system for detecting a hydrogen leakage in a fuel cell system includes: an outer shell configured to accommodate a hydrogen flow section; a hydrogen sensor; and a porous sheet disposed to delimit at least a part of a space within the outer shell and allowing permeation of hydrogen through the porous sheet in a thickness direction thereof. The hydrogen flow section is disposed in a region below the porous sheet, and the hydrogen sensor is disposed in a region above the porous sheet.

A fuel cell system includes a fuel cell, a cathode off-gas discharge channel, a gas-liquid separator, and a cover member. The gas-liquid separator includes a body, a first discharge channel including a first valve seat at an end, and a first valve device including a first valve element and a first driver. The cover member covers at least the first discharge channel and the first valve seat in the gas-liquid separator, and includes a gas channel defining portion that defines a gas channel communicating with the cathode off-gas discharge channel between the cover member and the gas-liquid separator. The gas channel is configured such that a cathode off-gas flowing into the cover member comes into contact with the first discharge channel and the first valve seat and does not come into contact with the first driver.

An ejector has a variable nozzle structure and is installed in a fuel cell recirculation line to supply new hydrogen and a recirculation gas. The ejector includes: a first housing having a first hole through which hydrogen is supplied and an orifice through which the hydrogen is discharged; a second housing disposed in the first housing and having a second hole into which the hydrogen passing through the first hole flows; and a poppet penetrating a third hole defined at one side of the second housing. The poppet is configured to adjust an area of a space opened by the orifice discharging the hydrogen. The hydrogen flowing into the second housing is discharged through a space between the other side opposite to the one side of the second housing and the poppet to move to the orifice.

A control device of a fuel cell system does not execute feedback control of an air valve in a case where a first condition in which a valve opening degree command value calculated by the control device is less than a command value threshold and a second condition in which a valve opening degree measurement value measured by an air valve opening degree sensor is less than a measurement value threshold are satisfied, and executes the feedback control of the air valve in a case where the first condition or the second condition is not satisfied.

A fuel gas injection apparatus includes a chamber, a heat exchanger, a supply manifold, injectors, and a mount body. The chamber is in communication with a fuel gas tank, and the heat exchanger is in communication with the chamber. The supply manifold is in communication with the heat exchanger and has a plurality of branched flow channels for flowing a fuel gas. The plurality of injectors detachably communicate with the branched flow channels of the supply manifold. The mount body is in communication with the plurality of injectors and guides the fuel gas injected from plurality of injectors to a fuel cell stack. The chamber and the heat exchanger are attached to the mount body.

The invention relates to a shut-off valve (1) for temporarily interrupting the supply of air to a fuel cell stack in a fuel cell system, said shut-off valve comprising a valve piston (3) which can move back and forth in a cylindrical housing bore (2) and is prestressed in the direction of a sealing seat (5) by the spring force of a spring (4), wherein a connection between an air inlet duct (6) and an air outlet duct (7) is established or interrupted depending on the axial position of the valve piston (3). According to the invention, inside the housing bore (2), one end of the valve piston (3) delimits a spring chamber (8) which accommodates the spring (4) and is subjected to ambient pressure, and the other end thereof delimits a control chamber (9) which can be connected to the air inlet duct (7) via a control valve (10). The invention also relates to a fuel cell system comprising a shut-off valve (1) according to the invention.

A method of controlling a fuel cell device includes: a step of purging a hydrogen supply unit of a fuel electrode and purging a gas supply unit of an oxidant electrode when an operation of the fuel cell device ends; a step of measuring a voltage between the fuel electrode and the oxidant electrode and determining whether the voltage is greater than a predetermined threshold; a step of continuing power generation in the fuel cell device when the voltage is greater than the predetermined threshold; and a step of depressurizing the hydrogen supply unit and the gas supply unit when the voltage is equal to or less than the predetermined threshold.

A fuel cell system having a fuel cell cooling circuit coupled to a battery cooling circuit through a coolant/coolant heat exchanger for removing heat from the fuel cell cooling circuit through the battery cooling circuit during normal steady state operation of the fuel cell system.

An aircraft propulsion system comprises a gas turbine engine arranged to provide propulsive thrust and a fuel cell system having an air input port, the aircraft propulsion system being configured such that air from a compressor of the gas turbine engine is provided to the air input port during operation of the aircraft propulsion system. The fuel cell system is able to provide appreciable electrical power at altitude without the need for a dedicated compressor.