Rehydration of fuel cells
AssigneeIntelligent Energy Limited
InventorsDamian Davies, Nathan Grange, Paul Alan Benson
Life of this patent
Estimating the term…
Abstract
One or more operating parameters, such as electrical current flow from and air flow to, a fuel cell stack within a fuel cell assembly is periodically modulated during rehydration intervals to intermittently increase hydration levels of the fuel cell stack independently of the electrical current demand on the fuel cell assembly from an external load, while maintaining electrical current delivery to that external load.
Claims14
An electrochemical fuel cell assembly comprising:
- a fuel cell stack comprising a number of fuel cells each having a membrane-electrode assembly and fluid flow plates for delivery of fuel and oxidant thereto, and an electrical output for delivery of current from the fuel cell stack;
- and
- a stack power controller comprising a switchable load device, the stack power controller adapted to periodically and temporarily increase the current drawn from the fuel cell stack, in addition to or instead of independent current demand external to the electrochemical fuel cell assembly, by passing current from the fuel cell stack through the switchable load device during rehydration intervals to increase the hydration level of the fuel cells.
An electrochemical fuel cell assembly comprising:
- a fuel cell stack comprising a number of fuel cells each having a membrane-electrode assembly and fluid flow plates for delivery of fuel and oxidant thereto, and an electrical output for delivery of current from the fuel cell stack;
- and
- a stack power controller for periodically and temporarily increasing the current drawn from the fuel cell stack, in addition to or instead of independent current demand extermal to the electrochemical fuel cell assembly, during rehydration intervals to increase the hydration level of the fuel cells,
- wherein the rehydration intervals each include a high current interval in which current drawn from the fuel cell stack is substantially higher than the normal operating current demand and an isolation interval in which the current drawn from the fuel cell stack is substantially lower than the normal operating current demand.
An electrochemical fuel cell assembly comprising:
- a fuel cell stack comprising a number of fuel cells each having a membrane-electrode assembly and fluid flow plates for delivery of fuel and oxidant thereto, and an electrical output for delivery of current from the fuel cell stack;
- a stack controller for modulating air flow through the fuel cell stack on a periodic basis independent of current demand on the fuel cell stack or the electrochemical fuel cell assembly to provide rehydration intervals that increase the hydration level of the fuel cells;
- and
- means for maintaining the current demand to a load external to the electrochemical fuel cell assembly during the rehydration intervals.
A method of operating an electrochemical fuel cell assembly having a fuel cell stack comprising a number of fuel cells each having a membrane-electrode assembly and fluid flow plates for delivery of fuel and oxidant thereto, and an electrical output for delivery of current from the fuel cell stack, the method comprising the steps of:
- periodically and temporarily increasing the current drawn from the fuel cell stack independent of current demand external to the electrochemical fuel cell assembly during rehydration intervals to increase the hydration level of the electrochemical fuel cells by passing current from the fuel cell stack through a switchable load device within the fuel cell assembly;
- and
- maintaining the current demand to a load external to the electrochemical fuel cell assembly during the rehydration intervals.
A method of operating an electrochemical fuel cell assembly having a fuel cell stack comprising a number of fuel cells each having a membrane-electrode assembly and fluid flow plates for delivery of fuel and oxidant thereto, and an electrical output for delivery of current from the fuel cell stack, the method comprising the steps of:
- modulating air flow through the fuel cell stack on a periodic basis independent of current demand on the fuel cell stack or the electrochemical fuel cell assembly to provide rehydration intervals that increase the hydration level of the fuel cells while maintaining the current demand to a load external to the electrochemical fuel cell assembly during the rehydration intervals.
Dependencies are inferred from the claim text.