A system and method of controlling water imbalance in an electrochemical cell is provided. The method includes determining a present water imbalance in the electrochemical cell by summing a water.sub.in and a water.sub.created less a water.sub.out. Water.sub.in represents an amount of water introduced into the electrochemical cell by an oxidant feed gas; water.sub.created represents an amount of water created by the electrochemical cell from the electrochemical reaction; and water.sub.out represents an amount of water discharged from the electrochemical cell by an oxidant exhaust gas. The method includes tracking a cumulative water imbalance during operation of the electrochemical cell by repeatedly determining the present water imbalance and continuing to sum the results during operation. And, the method also includes adjusting a flow rate of the oxidant feed gas entering the electrochemical cell based on the cumulative water imbalance.

Various systems and methods disclosed herein may include a fuel cell system that may dynamically respond to changes in steam concentration in the fuel cell system. The fuel cell system may include a fuel cell stack that produces an anode exhaust stream, an anode recycle blower that receives the anode exhaust stream and outputs an anode recycle stream, and a humidity sensor configured to measure the steam concentration of the anode recycle stream. The fuel cell system may also include a master controller configured to receive steam concentration measurement from the humidity sensor and control the operation of the anode recycle blower and/or other components based on the steam concentration measurement.

Proposed are a fuel cell system and a method of controlling the fuel cell system. The fuel cell system may comprise a discharge valve configured to adjust a flow rate between an inlet and an outlet, connected at the inlet to a water trap connected to an anode of a fuel cell stack, and connected at the outlet to an external exhaust line, and a controller configured to derive an error value on the basis of a difference between condensate water production amount and discharge amount of the anode of the fuel cell stack when the discharge valve is in an open state, configured to correct the condensate water production amount of the anode on the basis of the error value when the discharge valve is in a closed state, and configured to open the discharge valve when the corrected condensate water production amount exceeds a predetermined first reference value.

A power generation system includes: a power generation unit configured to discharge a flue gas; a housing configured to accommodate the power generation unit; a ventilator configured to ventilate the housing; a first gas channel through which a gas discharged from the ventilator flows; a second gas channel through which the flue gas from the power generation unit flows; a merging portion where the first gas channel and the second gas channel merge; a third gas channel through which the gases merged at the merging portion flow; a water trap unit connected to the first gas channel and including a water sealing structure; and a water discharge channel through which water in the water trap unit is discharged to an outside of the housing.

A method of controlling the operation of a fuel cell system is provided. The method includes diagnosing a water shortage state in a fuel cell stack based on degradation of cooling performance and deterioration of the fuel cell stack and determining a diagnosis level of the fuel cell system based on the diagnosed water shortage state of the fuel cell stack. In addition, a regenerative operation is performed by selecting a regenerative operation mode which corresponds to the determined diagnosis level.

A fuel cell system includes: a fuel cell that generates electricity using a fuel gas and an oxidant gas; a fuel gas supply path through which a fuel gas to be supplied to an anode of the fuel cell flows; a recycle gas path through which an anode off-gas emitted from the anode of the fuel cell is returned to the fuel gas supply path; a water reservoir that holds water separated from the anode off-gas flowing through the recycle gas path; a drainage path through which water stored in the water reservoir is drained; a valve provided on the drainage path; and a controller that determines, on the basis of a history of a flow rate of the anode off-gas, a length of time for which the valve continues to be opened for draining the water stored in the water reservoir.

A fuel cell vehicle on which a fuel cell system including a fuel cell is mounted includes a discharge mechanism configured to discharge moisture, generated by the fuel cell, from the fuel cell system to an outside of the vehicle, a camera configured to capture an image outside the vehicle, and an electronic control unit configured to determine whether predetermined control based on an information obtained from the image and executed or stopped in response to a driving status or drive mode of the vehicle in an on-state of an ignition switch is being executed, and, when it is determined that the predetermined control is being executed, execute a low discharge process in which a discharge flow rate of water vapor that is discharged from the discharge mechanism to the outside of the vehicle is reduced as compared to when it is determined that the predetermined control is stopped.

A method of diagnosing level sensor failure in a fuel cell water trap, the method may include: determining whether a water level of a level sensor is changed in a fuel cell water trap, adding an amount of charge according to an operating time and comparing the added amount of charge with a preset threshold amount of charge, according to the result of the, forcibly opening a drain valve according to determining whether a channel voltage of a specific channel is abnormal as the result of the comparison, and diagnosing a failure of the level sensor according to determining whether the channel voltage of the specific cell is recovered as a normal state when the drain valve is opened.

A fuel cell failure diagnostic apparatus is provided. The apparatus includes a water-level sensor that senses a water-level of water generated at an anode side of a fuel cell stack and stored in a water trap and a drain valve for the drain control of the generated water. A drain valve position sensor senses a position of the drain valve. A controller detects a failure situation by performing failure diagnosis based on the sensing information generated from the water-level sensor and the drain valve position sensor, and performs a corresponding control depending upon the failure situation.

Various systems and methods disclosed herein may include a fuel cell system that may dynamically respond to changes in steam concentration in the fuel cell system. The fuel cell system may include a fuel cell stack that produces an anode exhaust stream, an anode recycle blower that receives the anode exhaust stream and outputs an anode recycle stream, and a humidity sensor configured to measure the steam concentration of the anode recycle stream. The fuel cell system may also include a master controller configured to receive steam concentration measurement from the humidity sensor and control the operation of the anode recycle blower and/or other components based on the steam concentration measurement.