When a time point of occurrence of a stop state of a fuel cell system is predicted during traveling, a drying state control that causes a fuel cell stack to transition to a dry state is started a predetermined time (a required drying time) before the predicted time point of occurrence of the stop state.

Methods and systems are described for optimizing water discharge in fuel cell vehicles. The system includes a fuel cell stack, a blower for purging water from the fuel cell stack and a controller. The controller detects that an ambient temperature satisfies a threshold temperature. The controller determines the fuel cell vehicle is approaching a stopping location. The controller calculates a water discharge time prediction necessary to purge excess water from the fuel cell stack while the fuel cell vehicle is operating in response to detecting that the ambient temperature satisfies the threshold temperature and the fuel cell vehicle is approaching the stopping location. The water discharge time prediction is calculated based on the blower operating while the fuel cell stack is in at least one of an idle state and a stopped state as the fuel cell vehicle approaches the stopping location.

Methods and systems are described for optimizing water discharge in fuel cell vehicles. The system includes a fuel cell stack, a blower for purging water from the fuel cell stack and a controller. The controller detects that an ambient temperature satisfies a threshold temperature. The controller determines the fuel cell vehicle is approaching a stopping location. The controller calculates a water discharge time prediction necessary to purge excess water from the fuel cell stack while the fuel cell vehicle is operating in response to detecting that the ambient temperature satisfies the threshold temperature and the fuel cell vehicle is approaching the stopping location. The water discharge time prediction is calculated based on the blower operating while the fuel cell stack is in at least one of an idle state and a stopped state as the fuel cell vehicle approaches the stopping location.

Methods and apparatus for reducing the tendency for mold formation and accumulation in membrane-based humidifiers used in PEM fuel cell systems can include reducing the oxygen concentration and/or generating hydrogen peroxide within the humidifier upon shutdown of a fuel cell system. In some embodiments, a fuel cell system comprises valves and lines located and operable to facilitate introduction of hydrogen into the humidifier upon shutdown of the system. In some embodiments, a fuel cell humidifier comprises a catalyst for promoting the generation of hydrogen peroxide from hydrogen and oxygen, and/or comprises acidic gas transport layers.

Methods and apparatus for reducing the tendency for mold formation and accumulation in membrane-based humidifiers used in PEM fuel cell systems can include reducing the oxygen concentration and/or generating hydrogen peroxide within the humidifier upon shutdown of a fuel cell system. In some embodiments, a fuel cell system comprises valves and lines located and operable to facilitate introduction of hydrogen into the humidifier upon shutdown of the system. In some embodiments, a fuel cell humidifier comprises a catalyst for promoting the generation of hydrogen peroxide from hydrogen and oxygen, and/or comprises acidic gas transport layers.

A fuel cell system includes a fuel cell stack of a plurality of power generation cells and an impedance measuring device for measuring the impedance in the fuel cell stack. When stopping the operation of the fuel cell system, a method for stopping the operation of the fuel cell system operates the plurality of power generation cells to generate electric power, until the impedance value becomes equal to or greater than an objective impedance value. After the impedance value has become equal to or greater than the objective impedance value, the operation stopping method still continues the power generation of the multiple power generation cells for a given period of time.

The invention relates to a method for deactivating a fuel cell system (10) comprising a jet pump (28) for conveying an anode-side gas flow in a recirculation path (26), wherein the jet pump (28) comprises a metering valve (36) for metering H.sub.2. While the fuel cell system (10) is cooling, a flow passes through a drive nozzle (46) at least once in order to discharge condensed water. The t invention additionally relates to a jet pump (28) comprising a metering valve (36) and to the use of the method in order to deactivate a fuel cell system (10).

The invention relates to a method for deactivating a fuel cell system (10) comprising a jet pump (28) for conveying an anode-side gas flow in a recirculation path (26), wherein the jet pump (28) comprises a metering valve (36) for metering H.sub.2. While the fuel cell system (10) is cooling, a flow passes through a drive nozzle (46) at least once in order to discharge condensed water. The t invention additionally relates to a jet pump (28) comprising a metering valve (36) and to the use of the method in order to deactivate a fuel cell system (10).

A fuel cell module is configured or operated, or both, such that after a shut down procedure a fuel cell stack is discharged and has its cathode electrodes at least partially blanketed with nitrogen during at least some periods of time. If the fuel cell module is restarted in this condition, electrochemical reactions are limited and do not quickly re-charge the fuel cell stack. To decrease start up time, air is moved into the cathode electrodes before the stack is re-charged. The air may be provided by a pump, fan or blower driven by a battery or by the flow or pressure of stored hydrogen. For example, an additional fan or an operating blower may be driven by a battery until the fuel cell stack is able to supply sufficient current to drive the operating blower for normal operation.

A fuel cell module is configured or operated, or both, such that after a shut down procedure a fuel cell stack is discharged and has its cathode electrodes at least partially blanketed with nitrogen during at least some periods of time. If the fuel cell module is restarted in this condition, electrochemical reactions are limited and do not quickly re-charge the fuel cell stack. To decrease start up time, air is moved into the cathode electrodes before the stack is re-charged. The air may be provided by a pump, fan or blower driven by a battery or by the flow or pressure of stored hydrogen. For example, an additional fan or an operating blower may be driven by a battery until the fuel cell stack is able to supply sufficient current to drive the operating blower for normal operation.