Abstract: A system and method for quantifying an anode leak location in a fuel cell system. The system and method include determining there is a leak in an anode sub-system of a fuel cell stack and estimating a first effective leak area using a first leak flow value and first operating parameters. The system and method also include increasing airflow to a cathode side of the fuel cell stack and estimating a second leak effective area using a second leak flow value and second operating parameters. The system and method further include comparing the first leak effective area to the second leak effective area and determining an anode outflow leak location based on the comparison between the first and second leak effective areas.

Abstract: A combined water drain and diluent gas purge valve routes fluid from the anode side of a fuel cell to the cathode inlet. When a purge of diluent gas is requested, the valve opens, draining any liquid present in the sump of a water separation device, for example. After the liquid has drained, the diluent gas is purged. An anode bleed model using fuel injector feedback can determine the amount of gas exiting the valve, and can request the valve to close once the required amount of diluent is purged. During operation, an amount of hydrogen may exit the valve. Hydrogen passing through the valve can be catalytically consumed once it reaches the cathode electrode, causing the cathode exhaust, and the fuel cell exhaust to have a reduced hydrogen content.

Abstract: A system and method for controlling an injector in a fuel cell system. The method provides a variety of injector pulse widths for at least one predetermined duty cycle and determines an injector close time for each of the variety of injector pulse widths. The method also determines an error for the at least one predetermined duty cycle based on each of the provided injector pulse widths and uses the injector pulse width with the lowest error for the at least one predetermined duty cycle.

Abstract: A fuel cell system, including a plurality of bipolar plate assemblies, each assembly including a first plate and a second plate with an internal coolant flow path disposed therebetween, a flow path for a first reactant gas on a side of the first plate opposite the internal coolant flow path, and a flow path for a second reactant gas on a side of the second plate opposite the internal coolant flow path, and a cooling system configured to place coolant in thermal communication with the plurality of bipolar plate assemblies, wherein cycling pressure differentials between the internal coolant flow path and the external reactant gas flow paths cause expansion and contraction of a volume of coolant disposed within the bipolar plate assembly, thereby pumping coolant through the cooling system. A method of cooling a fuel cell-powered vehicle is also provided.

Abstract: Apparatus, methods, and systems for estimating hydrogen concentration and/or pressure in an anode compartment of a fuel cell stack in a fuel cell vehicle. In some implementations, the estimates are based on a correlation between a transient dip in voltage in response to an anode to cathode bleed event and a concentration of hydrogen in the anode compartment of a fuel cell stack. Some implementations may comprise initiating a bleed event, sensing a transient dip in voltage in response to the bleed event, and using the correlation to calculate an estimate of a concentration and/or pressure of the gas in the anode compartment. The sensitivity of the correlation and hence the accuracy of estimation may change with the power level and may be accounted for in the correlation.

Abstract: A fuel cell system, including a plurality of bipolar plate assemblies, each assembly including a first plate and a second plate with an internal coolant flow path disposed therebetween, a flow path for a first reactant gas on a side of the first plate opposite the internal coolant flow path, and a flow path for a second reactant gas on a side of the second plate opposite the internal coolant flow path, and a cooling system configured to place coolant in thermal communication with the plurality of bipolar plate assemblies, wherein cycling pressure differentials between the internal coolant flow path and the external reactant gas flow paths cause expansion and contraction of a volume of coolant disposed within the bipolar plate assembly, thereby pumping coolant through the cooling system. A method of cooling a fuel cell-powered vehicle is also provided.

Abstract: A system and method for controlling hydrogen gas flow to an anode side of a fuel cell stack using a pressure regulator in the event that an injector that normally injects the hydrogen gas into the fuel cell stack has failed in a stuck open position. During normal operation, the control of the injector is determined based on the pressure of an anode sub-system and the position of the pressure regulator is determined based on a supply pressure between the pressure regulator and the injector. If it is determined that the injector is stuck in an open position, then the position of the pressure regulator is controlled to the anode pressure instead of the supply pressure. If the pressure regulator is an electrical pressure regulator, then it is pulsed to mimic normal system operation. Alternately, another valve, such as a shut-off valve, can be employed to provide the flow pulsing.

Abstract: A system and method for quantifying an anode leak location in a fuel cell system. The system and method include determining there is a leak in an anode sub-system of a fuel cell stack and estimating a first effective leak area using a first leak flow value and first operating parameters. The system and method also include increasing airflow to a cathode side of the fuel cell stack and estimating a second leak effective area using a second leak flow value and second operating parameters. The system and method further include comparing the first leak effective area to the second leak effective area and determining an anode outflow leak location based on the comparison between the first and second leak effective areas.

Abstract: A system and method for detecting an intermittent failure of an injector that injects hydrogen gas fuel into the anode side of a fuel cell stack in a fuel cell system. The method includes operating the injector at a fixed injector pulse width and frequency, which causes the stack to generate a constant current, and therefore, a constant fuel consumption rate. While at a constant current, the injector is commanded to a constant duty cycle and frequency that matches the rate of fuel consumption in the fuel cell system. The resulting fuel pressure feedback is then monitored, and if it diverges from a defined nominal value, either in a constant or oscillatory manner, it can be determined that the injector has an intermittent opening failure. In one embodiment, the determination of the injector failure is performed during a shut-down sequence of the fuel cell system.

Abstract: A valve for a fuel cell system includes a valve housing having an inlet and an outlet formed therein. Each of the inlet and the outlet includes a passage formed therein to permit a fluid to flow through the valve housing. A movable member is disposed in the valve housing and is movable between an open position and a closed position. The movable member includes a sliding portion having a first flow regulator and a second flow regulator extending laterally outwardly therefrom. At least a portion of the first flow regulator is disposed in the passage of the inlet and at least a portion of the second flow regulator is disposed in the passage of the outlet when the movable member is in the closed position militating against a formation of ice across the entire opening of the inlet and the outlet.

Abstract: A system and method for preventing anode reactant starvation. The system includes a hydrogen source, an anode bleed valve, and a cell voltage monitor. The system also includes an anode sub-system pressure sensor and a controller configured to control the anode sub-system. The controller determines the average cell voltage and estimates the hydrogen molar fraction and/or nitrogen molar fraction in the anode sub-system. The controller also receives measurement data from the cell voltage monitor and the pressure sensor, and determines whether there is a decrease in the minimum cell voltage in response to changes in the anode pressure. If the controller detects a decrease in the minimum cell voltage in response to changes in the anode pressure, the controller corrects for the decrease by increasing anode pressure and/or by decreasing the molar fraction of nitrogen in the anode sub-system.

Abstract: A system for determining the concentration of hydrogen in an anode sub-system of a fuel cell system. The fuel cell system includes at least one fuel cell, an anode inlet, an anode outlet, an anode recirculation line, a source of hydrogen gas and an injector for injecting the hydrogen gas. First and second acoustic sensors are provided in the anode recirculation line and are spaced a known distance from each other. A controller that is responsive to the output signals from the first and second acoustic sensors determines the concentration of hydrogen gas in the anode recirculation line based on the time between when the controller receives the sensor signal from the first sensor and receives the sensor signal from the second sensor.

Abstract: A system and method for correcting an estimation of nitrogen in an anode side of a fuel cell stack. The system includes a fuel cell stack and a pressure sensor for measuring pressure in an anode sub-system. The system also includes a controller configured to control the estimation of nitrogen permeation from the cathode side to the anode side of the stack, where the controller determines if the pressure in the anode sub-system equilibrates with atmospheric pressure in a shorter period of time after shutdown compared to the time necessary for the anode sub-system to reach approximately atmospheric pressure after a previous shutdown or calibrated time value, and corrects the estimation of nitrogen in the anode side of the stack if the pressure equilibrates in a shorter period of time.

Abstract: A system and method for controlling an injector in a fuel cell system. The method provides a variety of injector pulse widths for at least one predetermined duty cycle and determines an injector close time for each of the variety of injector pulse widths. The method also determines an error for the at least one predetermined duty cycle based on each of the provided injector pulse widths and uses the injector pulse width with the lowest error for the at least one predetermined duty cycle.

Abstract: A valve for a fuel cell system includes a valve housing having an inlet and an outlet formed therein. Each of the inlet and the outlet includes a passage formed therein to permit a fluid to flow through the valve housing. A movable member is disposed in the valve housing and is movable between an open position and a closed position. The movable member includes a sliding portion having a first flow regulator and a second flow regulator extending laterally outwardly therefrom. At least a portion of the first flow regulator is disposed in the passage of the inlet and at least a portion of the second flow regulator is disposed in the passage of the outlet when the movable member is in the closed position militating against a formation of ice across the entire opening of the inlet and the outlet.

Abstract: A system and method for controlling hydrogen gas flow to an anode side of a fuel cell stack using a pressure regulator in the event that an injector that normally injects the hydrogen gas into the fuel cell stack has failed in a stuck open position. During normal operation, the control of the injector is determined based on the pressure of an anode sub-system and the position of the pressure regulator is determined based on a supply pressure between the pressure regulator and the injector. If it is determined that the injector is stuck in an open position, then the position of the pressure regulator is controlled to the anode pressure instead of the supply pressure. If the pressure regulator is an electrical pressure regulator, then it is pulsed to mimic normal system operation. Alternately, another valve, such as a shut-off valve, can be employed to provide the flow pulsing.

Abstract: A combined water drain and diluent gas purge valve routes fluid from the anode side of a fuel cell to the cathode inlet. When a purge of diluent gas is requested, the valve opens, draining any liquid present in the sump of a water separation device, for example. After the liquid has drained, the diluent gas is purged. An anode bleed model using fuel injector feedback can determine the amount of gas exiting the valve, and can request the valve to close once the required amount of diluent is purged. During operation, an amount of hydrogen may exit the valve. Hydrogen passing through the valve can be catalytically consumed once it reaches the cathode electrode, causing the cathode exhaust, and the fuel cell exhaust to have a reduced hydrogen content.

Abstract: A system and method for detecting an intermittent failure of an injector that injects hydrogen gas fuel into the anode side of a fuel cell stack in a fuel cell system. The method includes operating the injector at a fixed injector pulse width and frequency, which causes the stack to generate a constant current, and therefore, a constant fuel consumption rate. While at a constant current, the injector is commanded to a constant duty cycle and frequency that matches the rate of fuel consumption in the fuel cell system. The resulting fuel pressure feedback is then monitored, and if it diverges from a defined nominal value, either in a constant or oscillatory manner, it can be determined that the injector has an intermittent opening failure. In one embodiment, the determination of the injector failure is performed during a shut-down sequence of the fuel cell system.

Abstract: A system for determining the concentration of hydrogen in an anode sub-system of a fuel cell system. The fuel cell system includes at least one fuel cell, an anode inlet, an anode outlet, an anode recirculation line, a source of hydrogen gas and an injector for injecting the hydrogen gas. First and second acoustic sensors are provided in the anode recirculation line and are spaced a known distance from each other. A controller that is responsive to the output signals from the first and second acoustic sensors determines the concentration of hydrogen gas in the anode recirculation line based on the time between when the controller receives the sensor signal from the first sensor and receives the sensor signal from the second sensor.

Abstract: A system and method for correcting an estimation of nitrogen in an anode side of a fuel cell stack. The system includes a fuel cell stack and a pressure sensor for measuring pressure in an anode sub-system. The system also includes a controller configured to control the estimation of nitrogen permeation from the cathode side to the anode side of the stack, where the controller determines if the pressure in the anode sub-system equilibrates with atmospheric pressure in a shorter period of time after shutdown compared to the time necessary for the anode sub-system to reach approximately atmospheric pressure after a previous shutdown or calibrated time value, and corrects the estimation of nitrogen in the anode side of the stack if the pressure equilibrates in a shorter period of time.