Fuel cell system
The invention provides a reactant delivery system for a dead-headed PEM fuel cell system, comprising a fuel cell, a fuel supply, a purge valve, an inlet orifice, an outlet orifice, and a controller. A first fuel flow circuit is provided, wherein fuel is flowed from the fuel supply to the inlet orifice, through the fuel cell from the inlet orifice, and through the outlet orifice from the fuel cell to the purge valve. A second fuel flow circuit is also provided, wherein fuel is flowed from the fuel supply to the outlet orifice, through the fuel cell from the outlet orifice, and through the inlet orifice from the fuel cell to the purge valve. A valve means is coupled to the controller and adapted to transfer fuel flow between the first flow circuit and the second flow circuit.
1. A method of operating a fuel cell system, comprising:
coupling a hydrogen supply to an inlet of a fuel cell, the fuel cell having an outlet;
pressurizing the fuel cell inlet with hydrogen from the hydrogen supply while the outlet is closed;
reacting at least a portion of the hydrogen in the fuel cell to supply electrical current to a load while the outlet is closed;
opening the outlet of the fuel cell to allow hydrogen to flow through the fuel cell from the inlet to the outlet;
removing the hydrogen supply from the inlet of the fuel cell and closing the inlet of the fuel cell;
coupling the hydrogen supply to the outlet of the fuel cell;
pressurizing the fuel cell outlet with hydrogen from the hydrogen supply while the inlet is closed;
reacting at least a portion of the hydrogen in the fuel cell to supply electrical current to the load while the inlet is closed; and
opening the inlet of the fuel cell to allow hydrogen to flow through the fuel cell from the outlet to the inlet.
2. The method of claim 1 , further comprising:
alternating at successive time intervals of a predetermined size the steps of coupling the hydrogen supply to the inlet of the fuel cell and coupling the hydrogen supply to the outlet of the fuel cell.
3. The method of claim 1 , further comprising:
monitoring a performance parameter of the fuel cell; and
performing the step of coupling the hydrogen supply to the outlet of the fuel cell when the performance parameter falls below a predetermined level.
4. The method of claim 3 , wherein the performance parameter is a voltage of the fuel cell, and the predetermined threshold is 0.4 volts.
5. The method of claim 1 , wherein the act of opening the outlet of the fuel cell includes purging the fuel cell for a predetermined period of time, and wherein the act of opening the inlet of the fuel cell includes purging the fuel cell for a predetermined period of time.
6. The method of claim 1 , further comprising:
coupling a battery to the load to supply power to the load during the step of opening an outlet of the fuel cell; and
coupling the battery to the load to supply power to the load during the step of opening the inlet of the fuel cell.
7. The method of claim 1 , further comprising:
purging the fuel cell prior to the act of pressurizing the fuel cell inlet.
8. The method of claim 7 , further comprising:
monitoring a performance parameter of the fuel cell; and
performing the purging of the fuel cell in response to the performance parameter falling below a predetermined level.
9. The method of claim 1 , further comprising:
purging the fuel cell prior to the act of pressurizing the fuel cell outlet.
10. The method of claim 9 , further comprising:
monitoring a performance parameter of the fuel cell; and
performing the purging of the fuel cell in response to the performance parameter falling below a predetermined level.
11. A method of operating a fuel cell system comprising a fuel cell having a first orifice and a second orifice, the method comprising:
closing off the second orifice of the fuel cell;
pressurizing the fuel cell with hydrogen while the second orifice is closed by coupling the first orifice of the fuel cell to a hydrogen supply;
reacting at least a portion of the hydrogen in the fuel cell to supply electrical current to a load while the second orifice is closed;
closing the first orifice and opening the second orifice;
pressurizing the fuel cell with hydrogen while the first orifice is closed by coupling the second orifice of the fuel cell to the hydrogen supply; and
reacting at least a portion of the hydrogen in the fuel cell to supply electrical current to the load while the first orifice is closed.
12. A method of operating a fuel cell system, comprising:
closing off an exhaust flow path of an anode chamber of a fuel cell;
flowing hydrogen into a first orifice of the anode chamber while the exhaust flow path is closed off;
reacting at least a portion of the hydrogen in the anode chamber to supply electrical current to a load while the exhaust flow path is closed off;
flowing hydrogen into the exhaust flow path of the anode chamber; and
reacting at least a portion of the hydrogen in the anode chamber to supply electrical current to the load.