Online anode pressure bias to maximize bleed velocity while meeting emission constraint
AssigneeGM Global Technology Operations LLC
InventorsManish Sinha, Seth E. Lerner, Patrick Frost, Victor W. Logan, Balasubramanian Lakshmanan
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Abstract
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.
Claims20
A method for determining a flow rate of an anode exhaust gas through an anode bleed valve from an anode side of a fuel cell stack, said method comprising:
- estimating a bleed flow rate of the anode exhaust gas through the bleed valve that maintains a hydrogen concentration in the anode exhaust gas below a predetermined percentage based on the amount of air in a cathode output from the fuel cell stack, said bled anode exhaust gas being fed into the cathode output from the fuel cell stack;
- using a valve orifice model for the bleed valve to estimate an anode side pressure set-point that is necessary to supply the estimated bleed flow rate;
- and
- providing hydrogen to the anode side of the fuel cell stack that maintains the anode side pressure set-point.
A method for determining a flow of an anode exhaust gas from an anode side of a fuel cell stack, said method comprising:
- providing air from a compressor to a cathode side of the fuel cell stack;
- by-passing some of the air from the compressor around the fuel cell stack;
- determining how much anode exhaust gas can be output from the fuel cell stack and be mixed with compressor air that is provided to the cathode side and bypassed around the fuel cell stack that will maintain the amount of hydrogen in the mixed anode exhaust gas and air below a predetermined hydrogen concentration;
- and
- providing hydrogen to the anode side of the fuel cell stack that maintains an anode side pressure set-point for the determined amount of anode exhaust gas.
A system for determining a flow rate of an anode exhaust gas through an anode bleed valve from an anode side of a fuel cell stack, said system comprising:
- means for estimating a bleed flow rate of the anode exhaust gas through the bleed valve that maintains a hydrogen concentration in the anode exhaust gas that is bled from the fuel cell stack below a predetermined percentage based on the amount of air in a cathode output from the fuel cell stack, said bled anode exhaust gas being fed into the cathode output from the fuel cell stack;
- means for using a valve orifice model for the bleed valve to estimate an anode side pressure set-point that is necessary to supply the estimated bleed flow rate;
- and
- means for providing hydrogen to the anode side of the fuel cell stack that maintains the anode side pressure set-point.
Dependencies are inferred from the claim text.