Abstract: A method for reconditioning a fuel cell stack. The method includes periodically increasing the relative humidity level of the cathode input airflow to the stack to saturate the cell membrane electrode assemblies to be greater than the relative humidity levels during normal stack operating conditions. The method also includes providing hydrogen to the anode side of the fuel cell stack at system shut down while the membrane electrode assemblies are saturated without stack loads being applied so that the hydrogen crosses the cell membranes to the cathode side and reacts with oxygen to reduce stack contaminants.

Abstract: A system and method for determining whether there is a cross-over leak, or other failure, in a WVT unit that humidifies the cathode inlet airflow to a fuel cell stack in a fuel cell system. The fuel cell system includes an HFR circuit that determines the humidity level of the membranes in the fuel cell stack and an RH sensor that measures the relative humidity of the airflow to the cathode side of the fuel cell stack. The HFR humidity calculation is compared to RH measurements from the RH sensor, and if the difference between the two RH values is greater than a predetermined calibration value, then the system may determine that the WVT unit is failing and needs to be serviced or replaced.

Abstract: A fuel cell system that enables an assisted anode purge upon start-up is provided. The fuel cell system includes a fuel cell stack having a plurality of fuel cells with anodes and cathodes. The fuel cell stack has an anode supply manifold and an anode exhaust manifold in fluid communication with the anodes. The fuel cell system further includes a suction device in fluid communication with at least one of the anode supply manifold and the anode exhaust manifold. The suction device adapted to selectively draw a partial vacuum on the fuel cell stack during a start-up of the fuel cell system. Methods for starting the fuel cell system are also provided.

Abstract: A system and method for determining whether there is a cross-over leak, or other failure, in a WVT unit that humidifies the cathode inlet airflow to a fuel cell stack in a fuel cell system. The fuel cell system includes an HFR circuit that determines the humidity level of the membranes in the fuel cell stack and an RH sensor that measures the relative humidity of the airflow to the cathode side of the fuel cell stack. The HFR humidity calculation is compared to RH measurements from the RH sensor, and if the difference between the two RH values is greater than a predetermined calibration value, then the system may determine that the WVT unit is failing and needs to be serviced or replaced.

Abstract: A fuel cell system that enables an assisted anode purge upon start-up is provided. The fuel cell system includes a fuel cell stack having a plurality of fuel cells with anodes and cathodes. The fuel cell stack has an anode supply manifold and an anode exhaust manifold in fluid communication with the anodes. The fuel cell system further includes a suction device in fluid communication with at least one of the anode supply manifold and the anode exhaust manifold. The suction device adapted to selectively draw a partial vacuum on the fuel cell stack during a start-up of the fuel cell system. Methods for starting the fuel cell system are also provided.

Abstract: A fuel cell system that enables an assisted anode purge upon start-up is provided. The fuel cell system includes a fuel cell stack having a plurality of fuel cells with anodes and cathodes. The fuel cell stack has an anode supply manifold and an anode exhaust manifold in fluid communication with the anodes. The fuel cell system further includes a suction device in fluid communication with at least one of the anode supply manifold and the anode exhaust manifold. The suction device adapted to selectively draw a partial vacuum on the fuel cell stack during a start-up of the fuel cell system. Methods for starting the fuel cell system are also provided.

Abstract: A method for reconditioning a fuel cell stack. The method includes periodically increasing the relative humidity level of the cathode input airflow to the stack to saturate the cell membrane electrode assemblies to be greater than the relative humidity levels during normal stack operating conditions. The method also includes providing hydrogen to the anode side of the fuel cell stack at system shut down while the membrane electrode assemblies are saturated without stack loads being applied so that the hydrogen crosses the cell membranes to the cathode side and reacts with oxygen to reduce stack contaminants.

Abstract: A fuel cell system that increases stack stability by reducing the amount of liquid water droplets at the anode input of a fuel cell stack in the system. Re-circulated anode exhaust gas from the fuel cell stack and fresh hydrogen gas are sent to an anode heat exchanger so that both the fresh hydrogen gas and the re-circulated anode exhaust gas are heated to reduce the formation of water droplets in the anode input gas. Further, a portion of the heated cooling fluid directly from the fuel cell stack is sent to the heat exchanger to heat the fresh hydrogen gas and the re-circulation hydrogen before the cooling fluid is sent to an isolation heat exchanger to have its temperature reduced.

Abstract: A fuel cell system that enables an assisted anode purge upon start-up is provided. The fuel cell system includes a fuel cell stack having a plurality of fuel cells with anodes and cathodes. The fuel cell stack has an anode supply manifold and an anode exhaust manifold in fluid communication with the anodes. The fuel cell system further includes a suction device in fluid communication with at least one of the anode supply manifold and the anode exhaust manifold. The suction device adapted to selectively draw a partial vacuum on the fuel cell stack during a start-up of the fuel cell system. Methods for starting the fuel cell system are also provided.

Abstract: A fuel cell system that increases stack stability by reducing the amount of liquid water droplets at the anode input of a fuel cell stack in the system. Re-circulated anode exhaust gas from the fuel cell stack and fresh hydrogen gas are sent to an anode heat exchanger so that both the fresh hydrogen gas and the re-circulated anode exhaust gas are heated to reduce the formation of water droplets in the anode input gas. Further, a portion of the heated cooling fluid directly from the fuel cell stack is sent to the heat exchanger to heat the fresh hydrogen gas and the re-circulation hydrogen before the cooling fluid is sent to an isolation heat exchanger to have its temperature reduced.