A method for controlling a fuel cell (12) includes the following steps: measuring the fluid pressure in a first compartment from the anode and cathode compartments of the fuel cell (12); calculating a first target pressure for the fluid pressure in the second compartment of the fuel cell (12), the first target pressure depending on the fluid pressure measured in the first compartment; stabilizing the fluid pressure in the second compartment to the first target pressure; measuring the fluid pressure in the second compartment; calculating a second target pressure for the fluid pressure in the first compartment, the second target pressure depending on the fluid pressure measured in the second compartment; and stabilizing the fluid pressure in the first compartment at the second target pressure.

The invention relates to a fuel cell system comprising a stack of electrochemical cells forming a polymer ion-exchange membrane fuel cell (6), a fuel gas supply circuit and an oxidant gas supply circuit.

Said oxidant gas supply circuit comprises a compressor (3) intended to compress the ambient air before it enters the fuel cell (6), and an outlet exhaust (10) intended to discharge the gases leaving the fuel cell.

Said supply circuit is connected to the fuel cell at a first access point (7) and a second access point (8).

The system additionally comprises a switching element (11) that has two positions: a first position in which the outlet of the compressor (3) is connected to the first access point (7), and the second access point (8) is connected to the outlet exhaust (10), and a second position in which the outlet of the compressor (3) is connected to the second access point (8), and the first access point (7) is connected to the outlet exhaust (10).

The system is characterized in that it contains a moisture reservoir positioned in the oxidant gas supply circuit, upstream of the first access point (7).

An airflow control method of an air control system for a fuel cell stack (FCS) includes opening a recirculation valve by a controller to recirculate air through a compressor to increase a temperature of the air prior to entering the FCS to offset a FCS temperature below a predetermined threshold in response to identification to a cold-start event. The recirculation valve may be arranged with the compressor to recirculate air therethrough. The FCS may be arranged with the compressor and recirculation valve to selectively receive air therefrom. A sensor may measure thermal conditions of the FCS. The controller may be programmed to receive signals from the sensor indicating thermal conditions of the FCS, and to operate the recirculation valve based on the signals to recirculate air through the compressor to increase a temperature of the air prior to entering the FCS.

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.

The present disclosure provides a system and a method for purging the condensate water and hydrogen of a fuel cell stack, which may allow the condensate water and hydrogen discharged from a stack to be directly bypassed to an exhaust line of a humidifier rather than a shell side of the humidifier to be purged to the atmosphere according to the operation state and operation condition of the stack, thereby solving a problem in that an inverse voltage is generated upon cold operation of a fuel cell system, a flooding phenomenon occurs in the stack, or the like to improve the operation stability of the stack and the operation efficiency of the fuel cell system.

A PEM fuel or electrolysis cell with an extended lifetime, improved performance and uniform and stable operation is disclosed wherein a membrane electrode assembly is provided with a gradient of one or more properties in combination with a modification of one or more control parameters of the cell during its operation.

A fuel cell apparatus may include a stack, a stack air blower configured to supply external air to the stack, a humidifier configured to extract moisture contained in exhaust air and to supply the extracted moisture to external air supplied to the stack, a first bypass channel configured to allow exhaust air to bypass the humidifier, a first three-way valve controlled to adjust the amount of exhaust air that bypasses the humidifier, and a humidity sensor configured to sense the humidity of external air. The fuel cell apparatus may also include a second bypass channel configured to allow external air to bypass the humidifier, a second three-way valve controlled to adjust the amount of external air that bypasses the humidifier, and a controller configured to control the first three-way valve and the second three-way valve depending on the sensed humidity value of the external air.

Molten carbonate fuel cells (MCFCs) are operated at elevated pressure to provide increased operating voltage and/or enhanced CO.sub.2 utilization with a cathode input stream having a low CO.sub.2 content. It has been discovered that increasing the operating pressure of a molten carbonate fuel cell when using a low CO.sub.2-content cathode input stream can provide unexpectedly large increases in operating voltage while also reducing or minimizing the amount of alternative ion transport and/or enhancing CO.sub.2 utilization.

A pinhole determination method for a fuel cell includes steps of: blocking air supply to a fuel cell stack by a controller; measuring a cell voltage value of each of unit fuel cells of the fuel cell stack; and determining whether or not a pinhole is present by comparing the cell voltage value with an average cell voltage value.

The present invention enables a fuel cell to be stably started by minimizing a lack of air in a gas turbine when starting the fuel cell. This fuel cell system comprises: a gas turbine (11) having a compressor (21) and a combustor (22); a first compressed air supply line (26) that supplies compressed air (A1), which has been compressed by the compressor, to the combustor; a solid oxide fuel cell (SOFC) (13) having an air electrode and a fuel electrode; a second compressed air supply line (31) that supplies partially compressed air (A2), which has been compressed by the compressor, to the air electrode; a blower (33) that is disposed on the second compressed air supply line, and raises the pressure of the compressed air (A2); a circulation booster line (60) connecting the upstream side and downstream side of the blower in the second compressed air supply line; a control valve (61) disposed on the circulation booster line; a control valve (63) disposed between the circulation booster line in the second compressed air supply line and the SOFC; and a control device (62) that closes the control valves and opens the control valves to start the blower when starting the SOFC.