Abstract: A process for anode overpressure remedial action in a fuel cell system is provided. The process includes monitoring a pressure of hydrogen gas at an anode of a fuel cell stack of the fuel cell system, diagnosing a mechanically stuck open injector based upon the monitored pressure, and based upon diagnosing the mechanically stuck open injector, closing a valve within a hydrogen storage system to prevent flow of the hydrogen gas from a hydrogen storage tank into a gas line connecting the hydrogen storage tank to the mechanically stuck open injector and maintaining operation of the fuel cell stack to deplete the hydrogen gas at the anode.

Abstract: A system and method for a cathode subsystem in a fuel cell system. The system includes a fuel cell stack, a cathode inlet line that provides cathode air to a fuel cell stack and a cathode exhaust line that exhausts a cathode exhaust gas out of the fuel cell stack. Also included is a backpressure valve in the cathode exhaust line that is located downstream of a drip rail of the cathode exhaust line, where the drip rail includes a protrusion that prevents condensed water from building up near the backpressure valve. The drip rail further includes a sump that collects drips of condensed water from the protrusion of the drip rail. The system also includes a drain below a water vapor transfer unit that includes an orifice that is in a portion of the drain that is within the cathode exhaust line.

Abstract: A device and method for improving cathode catalytic heating by allowing independently for a draining of a liquid and a purging of a gas in a fuel cell at cold starts via a system including an anode drain and a cathode catalytic heating system connected by a purge tube, a sump external to the purge tube, and a pintle having a closed position, a first open position, and a second open position.

Abstract: A method for starting a cold or frozen fuel cell stack as efficiently and quickly as possible in a vehicle application is based upon a state of charge of a first power source such as a high voltage battery. Power flow between the first power source and fuel cell system is coordinated in conjunction with a specific load schedule and parallel control algorithms to minimize the start time required and optimize system warm-up.

Abstract: A device and method for improving cathode catalytic heating by allowing independently for a draining of a liquid and a purging of a gas in a fuel cell at cold starts via a system including an anode drain and a cathode catalytic heating system connected by a purge tube, a sump external to the purge tube, and a pintle having a closed position, a first open position, and a second open position.

Abstract: A device and method for ensuring proper fuel cell system warmup or shutdown during freeze conditions. A three-way valve is used in conjunction with a flow-controlling orifice to ensure that the orifice avoids ice blockage during frozen conditions. Dry, warm air is delivered as a slip stream under pressure to a cathode flowpath, where the construction of the orifice is such that it is structurally compliant to promote flexing in response to the pressurized slip stream, thereby helping to break up any small amount of ice that may have formed in or on the orifice.

Abstract: A method for shutting down a fuel cell system including operating a fuel cell stack. the method includes providing an increased cathode air flow so as to dry fuel cell membranes in the stack until a first desired level of high frequency resistance is achieved, rehydrating the cell membranes of the stack until a second desired level of high frequency resistance is achieved, and operating the stack with a decreased cathode input relative humidity until a third desired level of high frequency resistance is achieved.

Abstract: A system and method that monitor the rate of a voltage drop of fuel cells in a fuel cell stack to determine whether the voltage drop is a result of cathode reactant starvation or anode reactant starvation. The method looks at a falling voltage of a fuel cell to determine whether the rate of the fall in voltage indicates that hydrogen starvation of the anode of the fuel cell is occurring. The method also looks at the actual voltage of the fuel cell that is falling to determine whether it is a below a predetermined minimum voltage threshold also indicating that hydrogen starvation of the anode of the fuel cell is occurring. If hydrogen starvation is occurring, the method performs power limiting of the fuel cell stack either based on the rate or the voltage level.

Abstract: A system and method for a cathode subsystem in a fuel cell system. The system includes a fuel cell stack, a cathode inlet line that provides cathode air to a fuel cell stack and a cathode exhaust line that exhausts a cathode exhaust gas out of the fuel cell stack. Also included is a backpressure valve in the cathode exhaust line that is located downstream of a drip rail of the cathode exhaust line, where the drip rail includes a protrusion that prevents condensed water from building up near the backpressure valve. The drip rail further includes a sump that collects drips of condensed water from the protrusion of the drip rail. The system also includes a drain below a water vapor transfer unit that includes an orifice that is in a portion of the drain that is within the cathode exhaust line.

Abstract: A method for purging water from a fuel cell stack at fuel cell system shutdown. The method includes determining a stack water generation request to control the rate of drying of membranes in the stack and determining a cathode catalytic heating water generation request. A maximum charge a battery in the fuel cell system can accept is also determined. An ancillary power request for powering components of the fuel cell system during shutdown is determined. The method allocates how much of the water generation request will be fulfilled by operating the fuel cell stack to charge the battery and to provide the power needed for the ancillary power request, and how much of the water generation request will be fulfilled by cathode catalytic heating that produces water and heat in a cathode side of the fuel cell stack.

Abstract: A valve for a fuel cell system includes a valve housing having a valve seat formed therein. The valve seat includes an orifice 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 first end having an elongate portion and a generally conical shaped base. At least a portion of the base is disposed in the orifice of the valve seat when the movable member is in the closed position to militate against a formation of ice across the orifice of the valve seat.

Abstract: A system and method for selectively determining whether a freeze purge should be performed at shut-down of a fuel cell stack. The method includes identifying that the vehicle has been keyed off and then determining whether a stack membrane humidification value is less than a predetermined humidification value that identifies the humidification of membranes in fuel cells in the fuel cell stack. If the stack membrane humidification value is not less than the predetermined humidification value, then the method determines if the ambient temperature is below a predetermined ambient temperature, and if so, performs the freeze purge. If the ambient temperature is not below the predetermined ambient temperature, then the method performs a short non-freeze purge of the flow channels in the fuel cell stack. The method determines a wake-up time for a controller for a next time to determine whether a freeze purge should be performed.

Abstract: A method for starting a cold or frozen fuel cell stack as efficiently and quickly as possible in a vehicle application is based upon a state of charge of a first power source such as a high voltage battery. Power flow between the first power source and fuel cell system is coordinated in conjunction with a specific load schedule and parallel control algorithms to minimize the start time required and optimize system warm-up.

Abstract: A device and method for ensuring proper fuel cell system warmup or shutdown during freeze conditions. A three-way valve is used in conjunction with a flow-controlling orifice to ensure that the orifice avoids ice blockage during frozen conditions. Dry, warm air is delivered as a slip stream under pressure to a cathode flowpath, where the construction of the orifice is such that it is structurally compliant to promote flexing in response to the pressurized slip stream, thereby helping to break up any small amount of ice that may have formed in or on the orifice.

Abstract: A method for starting a cold or frozen fuel cell stack as efficiently and quickly as possible in a vehicle application is based upon a state of charge of a first power source such as a high voltage battery. Power flow between the first power source and fuel cell system is coordinated in conjunction with a specific load schedule and parallel control algorithms to minimize the start time required and optimize system warm-up.

Abstract: A system and method that monitor the rate of a voltage drop of fuel cells in a fuel cell stack to determine whether the voltage drop is a result of cathode reactant starvation or anode reactant starvation. The method looks at a falling voltage of a fuel cell to determine whether the rate of the fall in voltage indicates that hydrogen starvation of the anode of the fuel cell is occurring. The method also looks at the actual voltage of the fuel cell that is falling to determine whether it is a below a predetermined minimum voltage threshold also indicating that hydrogen starvation of the anode of the fuel cell is occurring. If hydrogen starvation is occurring, the method performs power limiting of the fuel cell stack either based on the rate or the voltage level.

Abstract: A fuel cell system that employs one or more wax elements to provide passive control. In one embodiment, a wax element device is positioned within a coolant stream pipe. The wax element device includes a wax element positioned within a container. An electrically conductive rod is positioned within the wax element and extends out of the pipe. As the wax element expands and contracts in response to temperature changes in the cooling fluid, the rod moves up and down to make various electrical contacts and control the various devices, such a coolant pump and a coolant fan. In another embodiment, the rod extends into a cathode exhaust pipe of the fuel cell system, and is coupled to a back-pressure valve therein. As the temperature of the cooling fluid changes, the wax element expands and contracts to control the position of the back-pressure valve.

Abstract: A system and method for determining whether valves in a fuel cell system bleed manifold unit (BMU) are blocked with ice or have otherwise failed. The system opens a first bleed valve, closes a second bleed valve and opens an exhaust valve, and then reads a pressure signal to determine whether there is flow through a flow restriction to determine whether the first bleed valve or the exhaust valve is blocked. The system then closes the exhaust valve, leaves the first bleed valve open, and again reads the pressure signal to determine the pressure drop across the flow restriction, which will indicate whether the flow restriction the pressure sensor lines are blocked. The system then closes the first bleed valve and opens the second bleed valve to determine whether the pressure signal indicates a flow through the second bleed valve.

Abstract: A technique for reducing the amount of water that accumulates in an anode exhaust gas bleed line in a fuel cell system. The system includes a fuel cell stack, a cathode exhaust line and an anode exhaust line. The anode exhaust gas line is coupled to an anode bleed valve. An anode bleed line is coupled to the bleed valve and the cathode exhaust gas line so the hydrogen in the bled anode exhaust gas is diluted by the cathode exhaust gas. The anode bleed line is coupled to the cathode exhaust gas line so that a stand-off portion of the bleed line extends through a wall of the cathode exhaust gas line and into the cathode exhaust flow therein so as to prevent water and water vapor clinging to the inside surface of the cathode exhaust gas line from draining into the anode bleed line.

Abstract: A system and method for selectively determining whether a freeze purge should be performed at shut-down of a fuel cell stack. The method includes identifying that the vehicle has been keyed off and then determining whether a stack membrane humidification value is less than a predetermined humidification value that identifies the humidification of membranes in fuel cells in the fuel cell stack. If the stack membrane humidification value is not less than the predetermined humidification value, then the method determines if the ambient temperature is below a predetermined ambient temperature, and if so, performs the freeze purge. If the ambient temperature is not below the predetermined ambient temperature, then the method performs a short non-freeze purge of the flow channels in the fuel cell stack. The method determines a wake-up time for a controller for a next time to determine whether a freeze purge should be performed.