Multiple pressure regime control to minimize RH excursions during transients
AssigneeGM Global Technology Operations LLC
InventorsDavid A. Arthur, Manish Sinha
Life of this patent
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Abstract
A control system for a fuel cell stack that controls the relative humidity of the cathode outlet gas during stack power transients to provide better cathode outlet gas relative humidity control by reducing the dynamic pressure range and thus the dynamic cathode outlet gas relative humidity range. In one embodiment, the control system uses a first narrower cathode pressure range based on stack current density during stack power transients to provide better cathode outlet gas relative humidity control, and uses a second wider cathode pressure range based on stack current density during low current density and steady-state current density to improve system efficiency by decreasing compressor parasitics.
Claims25
A fuel cell system comprising:
- a fuel cell stack receiving a cathode inlet airflow and outputting a cathode exhaust gas flow;
- a compressor for providing the cathode inlet airflow to the stack;
- a water vapor transfer device receiving the cathode inlet airflow from the compressor and the cathode exhaust gas flow from the fuel cell stack, said water vapor transfer device using water vapor in the cathode exhaust gas to humidify the cathode inlet air;
- and
- a controller for controlling the relative humidity of the cathode exhaust gas flow so as to control the relative humidity of the cathode inlet air, said controller causing a cathode of the fuel cell stack to operate in a first cathode pressure range based on the current density being produced by the stack if the stack current density is below a predetermined value, and causing a cathode of the fuel cell stack to operate in a second cathode pressure range based on the current density being produced by the stack if the stack current density is above the predetermined value, wherein the first and second pressure ranges are different and the second pressure range is narrower than the first pressure range.
A fuel cell system comprising:
- a fuel cell stack receiving a cathode inlet airflow and outputting a cathode exhaust gas flow;
- and
- a controller for controlling the relative humidity of the cathode exhaust gas flow so as to control the relative humidity of the cathode inlet airflow, said controller causing a cathode of the fuel cell stack to operate in a first cathode pressure range if the stack current density is below a predetermined current density or is in a steady state operation, and causing a cathode of the fuel cell stack to operate in a second cathode pressure range if the stack current density is above the predetermined value and is in a dynamic cycle, wherein the first and second pressure ranges are different.
A method for controlling the cathode pressure of a fuel cell stack, said method comprising:
- using a first cathode pressure range if the stack current density is below a predetermined current density or is in a steady state current density;
- and
- using a second cathode pressure range if the stack current density is above the predetermined value and is in a dynamic cycle.
Dependencies are inferred from the claim text.