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 selectively operating a fuel cell stack in response to loss of a voltage signal from one or more fuel cells in the stack. If the voltage signal from the one or more fuel cells is lost, the method performs one or more remedial actions to cause the fuel cell stack to operate in a more stack safe condition. The method then determines whether the cell or cells whose voltage signal is lost was healthy, such as operating above a predetermined voltage threshold, prior to the voltage signal being lost. If the cell voltage signal was above the voltage threshold, then the fuel cell stack is operated normally under the remedial actions, and if the voltage signal is below the voltage threshold, then the fuel cell stack is operated in a power limitation mode.

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: Systems and methods to control the delivery of coolant to a coolant loop within a vehicular fuel cell system. During periods of low power output from one or more fuel cell stacks, operation of a pump used to circulate coolant through the loop is intermittent, thereby reducing pump usage during such times. The frequency of pump operation, as measured by a pump on/off (i.e., pulsed) cycle, may be adjusted to keep a local temperature rise within the one or more stacks to no more than a small amount over the bulk stack temperature.

Abstract: A system and method for determining whether an anode injector that injects hydrogen gas into an anode side of a fuel cell stack has failed. The method includes monitoring a voltage of the fuel cell stack and performing spectral analysis of the stack voltage to identify amplitude peaks in the stack voltage. The method further includes determining whether the spectral analysis of the stack voltage has identified an amplitude peak at a location where an amplitude peak should occur if the injector is operating properly. If no amplitude peak is identified at that location, then the method determines that the injector is not operating properly. If an amplitude peak is identified at that location, then the method compares the amplitude peak to the desired amplitude peak to identify if it is within a threshold to determine if the injector is operating properly.

Abstract: A method for determining a flow of a gas through an injector and a flow of a gas through a valve in a fuel cell system. The method includes determining an injector flow estimation for the gas flowing through the injector and determining a valve flow estimation for the gas flowing through the valve. The method also includes calculating an error that is a difference between the injector flow estimation and the valve flow estimation and adjusting the flow of the gas through the valve based on the error.

Abstract: A system and method for detecting an anode pressure sensor failure in a fuel cell system. The system and method include a controller that sets an initial minimum anode pressure sensor value and an initial maximum anode pressure sensor value. The controller determines a desired time interval for sampling anode pressure measurements and determines a total number of samples of anode pressure measurements to be collected by the controller from an anode pressure sensor. The controller also compares a pressure difference between the initial or a measured minimum anode pressure and the initial or a measured maximum anode pressure to a predetermined pressure difference threshold and sets a pressure sensor fault if the pressure difference between the initial or measured minimum anode pressure and the initial or maximum anode pressure is less than the predetermined pressure difference threshold.

Abstract: A system and method for determining a loss of cooling fluid from a thermal sub-system in a fuel cell system. The method includes monitoring current feedback from a high temperature pump that pumps the cooling fluid through a coolant loop. A measured current from the pump is compared to an expected current for the system operating conditions, and if that current is significantly less than what is expected, then it may be as a result of low cooling fluid. If the measured current is less than the expected current for a predetermined period of time, then the system can take mitigating action as a result of a low cooling fluid. Further, if the pump speed is too low to provide an accurate current measurement, then it can be increased if an overflow tank level sensor indicates a low cooling fluid level.

Abstract: An anode reactant recycling system for a fuel cell is disclosed, the system including a hollow main body, a bleed conduit, an injector, a water separator, and a hydrophilic porous media. The anode reactant recycling system for a fuel cell is configured to minimize a required number of components, eliminate the need for the anode heat exchanger, use a single valve for removal of condensate and reactant byproducts from the anode reactant recycling system, and provide an upstream volume for startup pressurization.

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 fuel cell assembly is disclosed that utilizes a water transport structure extending from fuel cell plates of the assembly into fuel cell assembly manifolds, wherein the water transport structure facilitates the transport of liquid water from the fuel cell plates thereby minimizing the accumulation of liquid water and ice in the fuel cell stack.

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 fuel cell assembly is disclosed that utilizes a water transport structure extending from fuel cell plates of the assembly into fuel cell assembly manifolds, wherein the water transport structure facilitates the transport of liquid water from the fuel cell plates thereby minimizing the accumulation of liquid water and ice in the fuel cell stack.

Abstract: A method for determining the amount of fuel flow from a high pressure gas tank to the anode side of a fuel cell stack through pulsed injector. The anode sub-system pressure is measured just before the injector pulse and just after injector pulse and a difference between the pressures is determined. The difference between the pressures, the volume of the anode sub-system, the ideal gas constant, the anode sub-system temperature, the fuel consumed from the reaction in the fuel cell stack during the injection event and the fuel cross-over through membranes in the fuel cells of the fuel cell stack are used to determine the amount of hydrogen gas injected by the injector.

Abstract: A method for determining a flow of a gas through an injector and a flow of a gas through a valve in a fuel cell system. The method includes determining an injector flow estimation for the gas flowing through the injector and determining a valve flow estimation for the gas flowing through the valve. The method also includes calculating an error that is a difference between the injector flow estimation and the valve flow estimation and adjusting the flow of the gas through the valve based on the error.

Abstract: A fuel cell system includes a water vapor transfer unit and a fluid flow distribution feature, the water vapor transfer unit including a first plate having a plurality of first flow channels for receiving a flow of a first fluid therein, and a second plate having a plurality of second flow channels for receiving a flow of a second fluid therein. The fluid flow distribution feature is configured to control at least one of a volume of flow of the first fluid through the first flow channels and a volume of flow of the second fluid through the second flow channels, wherein at least one of a flow distribution of the first fluid across the first plate and a flow distribution of the second fluid across the second plate is varied.

Abstract: An anode reactant recycling system for a fuel cell is disclosed, the system including a hollow main body, a bleed conduit, an injector, a water separator, and a hydrophilic porous media. The anode reactant recycling system for a fuel cell is configured to minimize a required number of components, eliminate the need for the anode heat exchanger, use a single valve for removal of condensate and reactant byproducts from the anode reactant recycling system, and provide an upstream volume for startup pressurization.

Abstract: A system and method for determining a loss of cooling fluid from a thermal sub-system in a fuel cell system. The method includes monitoring current feedback from a high temperature pump that pumps the cooling fluid through a coolant loop. A measured current from the pump is compared to an expected current for the system operating conditions, and if that current is significantly less than what is expected, then it may be as a result of low cooling fluid. If the measured current is less than the expected current for a predetermined period of time, then the system can take mitigating action as a result of a low cooling fluid. Further, if the pump speed is too low to provide an accurate current measurement, then it can be increased if an overflow tank level sensor indicates a low cooling fluid level.