A system for capturing carbon dioxide in flue gas includes a fuel cell assembly including at least one fuel cell including a cathode portion configured to receive, as cathode inlet gas, the flue gas generated by the flue gas generating device or a derivative thereof, and to output cathode exhaust gas and an anode portion configure to receive an anode inlet gas and to output anode exhaust gas, a fuel cell assembly voltage monitor configured to measure a voltage across the fuel cell assembly, and a controller configured to receive the measured voltage across the fuel cell assembly from the fuel cell assembly voltage monitor, determine an estimated carbon dioxide utilization of the fuel cell assembly based on the measured voltage across the fuel cell assembly, and reduce the carbon dioxide utilization of the fuel cell assembly when the determined estimated carbon dioxide utilization is above a predetermined threshold utilization.

The purpose of the present invention is to provide fuel cell system capable of stable start-up and method for starting the fuel cell system. Fuel cell system includes SOFC, a turbocharger, oxidizing gas supply line, a control valve, oxidizing gas blow line, start-up air line for supplying the start-up air to the oxidizing gas supply line with a blower, and a control unit that, in state in which the control valve is closed and the blow valve is opened to supply the start-up air to the oxidizing gas supply line with the blower when the turbocharger is started, decreases the opening of the blow valve and, after the timing at which the opening of the blow valve starts to decrease, increases the opening of the control valve and then stops the supply of the starting air.

The present disclosure relates to systems and methods of using a proportional control valve in a fuel cell stack system. The fuel cell stack system, may comprise a fuel cell stack including an anode with an anode inlet and an anode outlet, and a cathode with a cathode inlet and a cathode outlet, and a control valve, which controls the flow of a fuel into the anode. The flow of fuel may be based on a pressure differential measured across any two of the anode inlet, the anode outlet, the cathode inlet, and the cathode outlet.

A stack current controller may be configured to determine a stack current request based on a state of charge of a battery, an error based on a difference between an actual coolant temperature and a coolant temperature setpoint, or both. A plurality of stack current levels may be implemented corresponding to different battery state-of-charge thresholds. The determined stack current magnitude may be the lowest current magnitude that provides sufficient heat to maintain a coolant temperature at the coolant temperature setpoint or within the coolant temperature threshold. The determined stack current magnitude may be the highest current magnitude that provides sufficient power while maintaining a coolant temperature at the coolant temperature setpoint or within the coolant temperature threshold.

A vehicle includes a fuel cell having an air inlet port and an air outlet port and an air supply system having a compressor connected in fluid communication with the inlet port and a throttle valve connected in fluid communication with the outlet port. A controller is programmed to change a position of the throttle valve based on a target mass air flow, a measured mass air flow, a measured pressure, and the position of the throttle valve.

A method of operating an aircraft includes providing a fuel cell system to power the aircraft, providing an airflow path through the fuel cell system, sensing a change mass air flow rate supplied to a compressor of the fuel cell system, and at least one of adjusting a restriction of airflow entering the airflow path in response to the sensed change in mass air flow rate, adjusting a restriction of airflow exiting the airflow path in response to the sensed change in mass air flow rate, and adjusting an air scoop to gather a different amount of air into the airflow path. A method of operating an aircraft includes sensing a change in ambient pressure supplied to an airflow path and adjusting a restriction of airflow exiting the airflow path in response to a sensed change in ambient pressure.

The present disclosure relates to a method of recovering performance of a fuel cell stack in a fuel cell system of a vehicle. The method includes determining whether the fuel cell stack is in a state in which a stack performance recovery operation is possible based on information collected from the vehicle using a predetermined stack state determination criterion, determining whether the vehicle is in a state in which the stack performance recovery operation is possible based on operation information of a fuel cell system, and performing the stack performance recovery operation upon determining that the fuel cell stack is in the state in which the stack performance recovery operation is possible and that the vehicle is in the state in which the stack performance recovery operation is possible.

A method for controlling a carbon dioxide utilization in a fuel cell assembly includes: measuring a voltage across the fuel cell assembly; determining an estimated carbon dioxide utilization of the fuel cell assembly based on at least the measured voltage across the fuel cell assembly by determining an expected voltage of the fuel cell assembly based on at least a temperature of the fuel cell assembly, a current density across the fuel cell assembly, a fuel utilization of the fuel cell assembly, and a cathode oxygen utilization of the fuel cell assembly; determining the estimated carbon dioxide utilization based on a comparison between the measured voltage and the determined expected voltage; comparing the determined estimated carbon dioxide utilization to a predetermined threshold utilization; and upon determining that the determined estimated carbon dioxide utilization is higher than the predetermined threshold utilization, reducing the carbon utilization of the fuel cell assembly.

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 pressure control system of a fuel cell stack includes: an air supply control unit for controlling a revolutions per minute (RPM) of an air compressor for supplying air to a cathode side of the fuel cell stack based on a required output of the fuel cell stack; a hydrogen supply control unit for controlling a pressure at an anode side of the fuel cell stack with a target pressure based on the required output of the fuel cell stack; and a differential pressure control unit for controlling the air supply control unit or the hydrogen supply control unit to calculate a differential pressure between the anode side and the cathode side of the fuel cell stack, and to modify the target pressure or the RPM of the air compressor based on the calculated differential pressure.