Consumption-based fuel cell monitoring and control

• US 20050266284A1
• Filed: 05/28/2004
• Published: 12/01/2005
• Est. Priority Date: 05/28/2004
• Status: Active Grant

• Current Assignee: DCNS SA (Government of France)
• Original Assignee: IdaTech LLC (IdaTech Ltd.)
• Inventors: Scharf, Mesa
• Granted Patent: US 7,842,428 B2
• Time in Patent Office: Days
• US Class Current: 429/410
• CPC Class Codes: H01M 8/04089 of gaseous reactants
• CPC Class Codes: H01M 8/04402 of anode exhausts
• CPC Class Codes: H01M 8/04589 of fuel cell stacks
• CPC Class Codes: H01M 8/04753 of fuel cell reactants
• CPC Class Codes: H01M 8/0612 from carbon-containing material
• CPC Class Codes: H01M 8/0662 Treatment of gaseous reactants or gaseous residues, e.g. cleaning
• CPC Class Codes: Y02E 60/50 Fuel cells
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product

Abstract

Fuel cell systems and methods for controlling the operation of components of the fuel cell system, such as which may include a fuel source and a fuel cell stack. In some examples, a fuel source is adapted to provide supply fuel to a fuel cell stack at a supply pressure. In some systems, fuel not used by the fuel cell stack is discharged through at least one exit orifice at an exit pressure. In some examples, a control system is adapted to control operation of one or both of the fuel source and the fuel cell stack based on the flow of unused fuel. In some examples, a target pressure is determined based on the level of electrical current produced by a fuel cell stack, such that when fuel is supplied at the target pressure, the fuel cell stack consumes a given proportion of the supply fuel.

Claims

1. A fuel cell system comprising:

a fuel source adapted to provide supply fuel at a supply pressure;

a fuel cell stack including at least one fuel cell, wherein the fuel cell stack is adapted to receive the supply fuel, to produce electrical current from the received supply fuel, and to discharge unused fuel at an exit pressure; and

a control system adapted to detect the exit pressure and to determine the flow of unused fuel based on the exit pressure.

2. The fuel cell system of claim 1, wherein the control system is further adapted to control operation of at least one of the fuel source and the fuel cell stack based on the determined flow of unused fuel.

3. The fuel cell system of claim 1, in which the control system is adapted to determine the flow of unused fuel by utilizing the equation F=K{square root}{square root over (P)}, where F is the flow of unused fuel, K is a constant, and P is the exit pressure.

4. The fuel cell system of claim 2, in which the control system is adapted to detect the electrical current produced by the fuel cell stack, and to control the fuel source to provide the supply fuel at a supply pressure based on the electrical current produced by the fuel cell stack.

5. The fuel cell system of claim 1, in which the control system is further adapted to determine the flow of supply fuel.

6. The fuel cell system of claim 5, in which the control system is adapted to determine the flow of supply fuel based on the electrical current produced by the fuel cell stack and the exit pressure.

7. The fuel cell system of claim 5, in which the fuel source is adapted to produce the supply fuel from one or more feedstocks, and the control system is further adapted to control operation of the fuel source based on the determined flow of supply fuel.

8. The fuel cell system of claim 1, wherein the fuel source includes at least one hydrogen-storage device.

9. The fuel cell system of claim 1, wherein the fuel source includes a fuel processor adapted to produce the supply fuel from at least one feedstock.

10. The fuel cell system of claim 9, wherein the supply fuel is hydrogen gas.

11. The fuel cell system of claim 10, wherein the at least one feedstock includes water and at least one carbon-containing feedstock.

12. The fuel cell system of claim 11, wherein the fuel processor is adapted to produce hydrogen gas by steam reforming the water and the at least one carbon-containing feedstock.

13. The fuel cell system of claim 10, wherein the fuel source further includes at least one separation device adapted to selectively reduce the concentration of impurities in the supply fuel.

14. An energy-producing and consuming assembly comprising:

a fuel cell system according to claim 1;

and

at least one energy-consuming device adapted to exert an applied load on the fuel cell system.

15. An energy-producing and consuming assembly comprising:

a fuel cell system according to claim 2;

and

at least one energy-consuming device adapted to exert an applied load on the fuel cell system.

16. A fuel cell system comprising:

a fuel source adapted to provide supply fuel at a supply pressure;

a fuel cell stack including at least one fuel cell, wherein the fuel cell stack is adapted to receive supply fuel from the fuel source at the supply pressure, to use a portion of the received fuel to produce electrical power, and to discharge unused fuel through one or more exit orifices; and

a control system adapted to detect the level of electrical current produced, to determine a target supply pressure at which the fuel cell stack consumes a given proportion of the supply fuel for a given level of electrical current produced by the fuel cell stack, and to control operation of the fuel cell stack based on the target supply pressure.

17. The fuel cell system of claim 16, in which the control system is adapted to control operation of the fuel source in a manner tending to change the supply pressure to the target pressure.

18. The fuel cell system of claim 17, in which the control system is adapted to detect a change in the electrical current produced by the fuel cell stack, and to change the target supply pressure based on the detected change in the electrical current.

19. The fuel cell system of claim 16, in which the fuel source is adapted to produce the supply fuel from one or more feedstocks, and the control system is adapted to control use of the feedstocks by the fuel source based on the determined target supply pressure.

20. The fuel cell system of claim 16, in which the fuel cell stack is adapted to discharge unused fuel continuously, at least one of the one or more exit orifices is adapted to be selectively adjusted, and the control system is adapted to adjust the at least one of the one or more exit orifices to vary the supply pressure.

21. The fuel cell system of claim 16, in which the fuel cell stack is adapted to discharge unused fuel intermittently, and the control system is adapted to selectively adjust one or more of the frequency and duration of each discharge.

22. The fuel cell system of claim 16, wherein the fuel source includes at least one hydrogen-storage device.

23. The fuel cell system of claim 16, wherein the fuel source includes a fuel processor adapted to produce the supply fuel from at least one feedstock.

24. The fuel cell system of claim 23, wherein the supply fuel is hydrogen gas.

25. The fuel cell system of claim 24, wherein the at least one feedstock includes water and at least one carbon-containing feedstock.

26. The fuel cell system of claim 25, wherein the fuel processor is adapted to produce hydrogen gas by steam reforming the water and the at least one carbon-containing feedstock.

27. The fuel cell system of claim 24, wherein the fuel source further includes at least one separation device adapted to selectively reduce the concentration of impurities in the supply fuel.

28. An energy-producing and consuming assembly comprising:

a fuel cell system according to claim 16;

and

at least one energy-consuming device adapted to exert an applied load on the fuel cell system.

29. A method of operating a fuel cell system, comprising:

producing a supply fuel at a supply pressure;

applying oxidant and the supply fuel to a fuel cell stack, which includes at least one fuel cell, and which is adapted to produce electrical current therefrom;

discharging fuel unused by the fuel cell stack through an exit orifice at an exit pressure;

detecting the exit pressure;

determining the flow of unused fuel based on the exit pressure; and

controlling production of the supply fuel based on the determined flow of unused fuel.

30. The method of claim 29, in which determining the flow of unused fuel includes solving the equation F=K{square root}{square root over (P)}, where F is the flow of unused fuel, K is a constant, and P is the exit pressure.

31. The method of claim 29, further comprising detecting the electrical current produced by the fuel cell stack, and controlling production includes controlling production of the supply fuel at a pressure based on the electrical current produced by the fuel cell stack.

32. The method of claim 29, further comprising determining the flow of supply fuel, and controlling production of the supply fuel based on the determined flow of supply fuel.

33. The method of claim 32, in which producing a supply fuel includes determining the efficiency of the production of the supply fuel based on the determined flow of supply fuel, and controlling production of the supply fuel includes controlling the production of the supply fuel in a manner improving the efficiency of the production of the supply fuel.

34. The method of claim 32, in which producing a supply fuel includes producing the supply fuel using a chemical process, and controlling production of the supply fuel includes determining the stoichiometry of the chemical process based on the determined flow of supply fuel, and controlling production of the supply fuel based on the determined stoichiometry.

35. The method of claim 32, in which determining the flow of supply fuel includes detecting the electrical current produced by the fuel cell stack, and determining the flow of supply fuel based on the electrical current produced by the fuel cell stack and the exit pressure.

36. The method of claim 32, in which supplying a supply fuel includes producing the supply fuel from one or more feedstocks based on the determined flow of supply fuel.

37. A method of operating a fuel cell system, comprising:

providing supply fuel at a supply pressure;

applying oxidant and the supply fuel to a fuel cell stack, which includes at least one fuel cell, and which is adapted to produce electrical current therefrom;

discharging fuel unused by the fuel cell stack;

detecting the level of electrical current produced;

determining a target pressure of the supply fuel at which the fuel cell stack consumes a given proportion of the supply fuel for a given level of electrical current produced by the fuel cell stack; and

maintaining the supply pressure at about the target pressure.

38. The method of claim 37, further comprising detecting a change in the electrical current produced by the fuel cell stack, and changing the target pressure based on the detected change in the electrical power.

39. The method of claim 37, in which providing supply fuel includes applying one or more feedstocks to a fuel processor apparatus in a manner producing the supply fuel at a supply pressure, and in which maintaining the supply pressure includes applying the one or more feedstocks to the fuel processor apparatus in a manner maintaining the supply pressure at about the target pressure.