摘要:
A method that employs a model based approach to determine a maximum anode pressure set-point based on existing airflow in the exhaust gas line. This approach maximizes anode flow channel velocity during bleed events while meeting the hydrogen emission constraint, which in turn increases the amount of water purged from the anode flow channels to increase stack stability.
摘要:
A method that employs a model based approach to determine a maximum anode pressure set-point based on existing airflow in the exhaust gas line. This approach maximizes anode flow channel velocity during bleed events while meeting the hydrogen emission constraint, which in turn increases the amount of water purged from the anode flow channels to increase stack stability.
摘要:
A method for providing a fast and reliable start-up of a fuel cell system. The method uses a stack voltage response to a load to assess if hydrogen and oxygen are being sufficiently distributed to all of the fuel cells by coupling an auxiliary load to the fuel cell stack until a predetermined minimum cell voltage has been reached or a first predetermined time period has elapsed. The method then determines whether a minimum cell voltage has dropped to a first predetermined voltage and, if so, reduces the maximum power allowed to be below the first predetermined voltage value, determines whether the minimum cell voltage in the stack is below a second predetermined voltage, or determines whether the minimum cell voltage drop rate is greater than a predetermined voltage drop rate. If none of these conditions are met, the method returns to loading the stack with system components.
摘要:
A method for providing a fast and reliable start-up of a fuel cell system. The method uses a stack voltage response to a load to assess if hydrogen and oxygen are being sufficiently distributed to all of the fuel cells by coupling an auxiliary load to the fuel cell stack until a predetermined minimum cell voltage has been reached or a first predetermined time period has elapsed. The method then determines whether a minimum cell voltage has dropped to a first predetermined voltage and, if so, reduces the maximum power allowed to be below the first predetermined voltage value, determines whether the minimum cell voltage in the stack is below a second predetermined voltage, or determines whether the minimum cell voltage drop rate is greater than a predetermined voltage drop rate. If none of these conditions are met, the method returns to loading the stack with system components.
摘要:
A control strategy for bleeding an anode side of fuel cell stack in a fuel cell system that improves water management and addresses durability and performance concerns. The method includes determining when to begin the anode bleed, typically by estimating or measuring the amount of nitrogen in the anode side of the stack. The method also includes determining when to end the anode bleed based on the volume of gas that has been bled. The method determines the mole flow rate of the anode gas flowing through a bleed valve, integrates the mole flow rate to get the number of moles of the gas that have passed through the bleed valve, determines a desired amount of moles to be bled, and ends the bleed when the actual number of moles of the gas equals the desired number of moles of the gas.
摘要:
A control strategy for bleeding an anode side of fuel cell stack in a fuel cell system that improves water management and addresses durability and performance concerns. The method includes determining when to begin the anode bleed, typically by estimating or measuring the amount of nitrogen in the anode side of the stack. The method also includes determining when to end the anode bleed based on the volume of gas that has been bled. The method determines the mole flow rate of the anode gas flowing through a bleed valve, integrates the mole flow rate to get the number of moles of the gas that have passed through the bleed valve, determines a desired amount of moles to be bled, and ends the bleed when the actual number of moles of the gas equals the desired number of moles of the gas.
摘要:
A system and method for breaking-in and humidifying membrane-electrode-assemblies (MEAs) in a fuel cell stack. The method includes performing voltage cycling and humidification of the MEAs in the stack, including one or more temperature steps wherein current density of the stack is cycled within a predetermined range for each of the one or more temperature steps. The method also includes maintaining a fuel cell stack voltage within a predetermined range, and maintaining anode and cathode reactant flows at an approximate set-point during the current density cycling of the one or more temperature steps to break-in and humidify the MEAs in the stack so that the stack is able to operate at a predetermined threshold for a fuel cell stack voltage output capability.
摘要:
A graded electrode is described. The graded electrode includes a substrate; and at least two electrode layers on the substrate forming a combined electrode layer, a composition of the at least two electrode layers being different, the combined electrode layer having an average level of the property that changes across the substrate. Fuel cells using graded electrodes and methods of making graded electrodes are also described.
摘要:
A method for determining the health of the membranes in a fuel cell stack. The total parasitic current of the fuel cells in the stack is determined. From the total parasitic current, the shorting resistance and the cross-over parasitic current are determined. The health of the membranes is then determined from the cross-over parasitic current and the shorting resistance.
摘要:
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.