Fuel cell system with electrokinetic pump

• US 20050233195A1
• Filed: 04/19/2004
• Published: 10/20/2005
• Est. Priority Date: 04/19/2004
• Status: Active Grant

• Current Assignee: Teleflex Life Sciences Pte., Ltd. (Teleflex Incorporated)
• Original Assignee: Eksigent Technologies LLC
• Inventors: Paul, Phillip H., Arnold, Don W., Anex, Deon S.
• Granted Patent: US 7,521,140 B2
• Time in Patent Office: Days
• US Class Current: 429/415
• CPC Class Codes: H01M 8/04007 related to heat exchange
• CPC Class Codes: H01M 8/04186 of liquid-charged or electrolyte-charged reactants
• CPC Class Codes: H01M 8/0432 Temperature; Ambient temperature
• CPC Class Codes: H01M 8/04447 of anode reactants at the inlet or inside the fuel cell
• 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: Y02E 60/50 Fuel cells

Abstract

A fuel cell system having a fuel cell, the fuel cell having a membrane-electrode assembly; a fuel reservoir containing a liquid fuel; a conduit coupling the fuel reservoir to the fuel cell; and an electrokinetic fuel pump coupled to the conduit, the electrokinetic fuel pump having a plurality of electrodes; wherein the electrokinetic fuel pump moves fuel from the fuel reservoir through the conduit to the fuel cell; and wherein the electrokinetic fuel pump electrodes do not deleteriously affect the performance of the membrane-electrode assembly.

Claims

1. A fuel cell system comprising:

a) a fuel cell comprising a membrane-electrode assembly;

b) a fuel reservoir containing a liquid fuel;

c) a conduit coupling the fuel reservoir to the fuel cell; and

d) an electrokinetic fuel pump coupled to the conduit, the electrokinetic fuel pump comprising a plurality of electrodes;

wherein the electrokinetic fuel pump moves fuel from the fuel reservoir through the conduit to the fuel cell; and

wherein the electrokinetic fuel pump electrodes do not deleteriously affect the performance of the membrane-electrode assembly.

2. The fuel cell system of claim 1 wherein the electrokinetic fuel pump electrodes further comprise capacitive carbon electrodes.

3. The fuel cell system of claim 1 further comprising:

a) a mixing chamber coupled to the conduit; and

b) a high temperature fuel reformer;

wherein the electrokinetic fuel pump moves fuel from the reservoir through the conduit, the mixing chamber, and the high temperature fuel reformer to the fuel cell.

4. The fuel cell system of claim 1 wherein the fuel cell produces a current;

and wherein the fuel cell system further comprises;

a current monitor for monitoring the current produced by the fuel cell; and

a controller coupled to the current monitor and to the electrokinetic fuel pump, the controller controlling the flow rate of the electrokinetic fuel pump based upon the current detected by the current monitor.

5. The fuel cell system of claim 1 further comprising a plurality of electrokinetic stirring pumps positioned inside of the fuel cell for stirring the fuel in the fuel cell.

6. The fuel cell system of claim 5 wherein the fuel cell produces a current;

and wherein the fuel cell system further comprises;

a current monitor for monitoring the current produced by the fuel cell;

a controller coupled to the current monitor, the electrokinetic fuel pump, and to the plurality of electrokinetic stirring pumps;

wherein the controller controls the flow rate of the electrokinetic fuel pump and the flow rate of the electrokinetic stirring pumps based upon the current detected by the current monitor.

7. The fuel cell system of claim 5 further comprising:

a temperature sensor for sensing a temperature of the fuel cell;

a controller coupled to the temperature sensor and to the plurality of electrokinetic stirring pumps;

wherein the controller controls the flow rate of the plurality of electrokinetic stirring pumps based upon the temperature sensed by the temperature sensor.

8. The fuel cell system of claim 5 further comprising:

a current monitor for monitoring the current produced by the fuel cell;

a temperature sensor for sensing the temperature of the fuel cell; and

a controller coupled to the current monitor, the temperature sensor, the electrokinetic fuel pump, and the plurality of electrokinetic stirring pumps;

wherein the controller controls the flow rate of at least one of the electrokinetic fuel pump and the plurality of electrokinetic stirring pumps based upon a current sensed by the current monitor and a temperature sensed by the temperature sensor.

9. The fuel cell system of claim 5 wherein the fuel cell further comprises at least one gas permeable membrane.

10. The fuel cell system of claim 5 wherein the fuel cell further comprises

a membrane-electrode assembly having an anode and a cathode;

and

an electrokinetic recirculation pump for pumping reaction products generated at the cathode to the anode.

11. The fuel cell system of claim 10 further comprising:

a concentration sensor to detect fuel concentration at the anode; and

a controller coupled to the concentration sensor and the electrokinetic recirculation pump;

wherein the controller controls the flow rate of the electrokinetic recirculation pump based on a concentration sensed by the concentration sensor.

12. The fuel cell system of claim 11 further comprising a condenser for condensing reaction products generated at the cathode.

13. The fuel cell system of claim 5 further comprising a plurality of heat conducting posts inside of the fuel cell.

14. The fuel cell system of claim 5 further comprising a plurality of heat conducting fins inside of the fuel cell.

15. The fuel cell system of claim 5 further comprising a plurality of heat conducting fins in thermal contact with an outer surface of the fuel cell.

16. The fuel cell system of claim 5 wherein the fuel cell is formed as a cylinder having a center channel;

and wherein the fuel is delivered to the fuel cell along the center channel.

17. The fuel cell system of claim 5 wherein the fuel is delivered to the fuel cell using a fuel distribution manifold.

18. The fuel cell system of claim 1 wherein the fuel cell is formed as a cylinder having an outer circumferential channel;

and the fuel is delivered to the fuel cell along the outer circumferential channel.

19. A fuel cell system comprising:

a) a fuel cell comprising a membrane-electrode assembly;

b) a fuel reservoir containing a liquid fuel;

c) a conduit coupling the fuel reservoir to the fuel cell;

d) an electrokinetic fuel pump coupled to the conduit, the electrokinetic fuel pump comprising a plurality of electrodes;

e) a mixing chamber coupled to the conduit; and

f) an electrokinetic mixing pump coupled to the conduit, the electrokinetic mixing pump comprising a plurality of electrodes and being adapted for mixing the fuel; and

wherein the electrokinetic fuel pump moves the fuel from the fuel reservoir through a first portion of the conduit to the mixing chamber;

the electrokinetic mixing pump moves the fuel from the mixing chamber through a second portion of the conduit to the fuel cell; and

the electrokinetic fuel pump electrodes and the electrokinetic mixing pump electrodes do not deleteriously affect the performance of the membrane-electrode assembly.

20. The fuel cell system of claim 19 wherein the electrokinetic mixing pump operates in an oscillatory mode.

21. The fuel cell system of claim 20 wherein the electrokinetic mixing pump further comprises a plurality of check valves.

22. A fuel cell system comprising:

a) a fuel cell having a membrane-electrode assembly and a reservoir;

b) a fuel delivery system providing fuel to the fuel cell; and

c) a plurality of electrokinetic stirring pumps positioned inside of the reservoir for stirring the fuel in the fuel cell.

23. A fuel cell system comprising:

a) a plurality of fuel cells electrically connected together;

b) a fuel reservoir containing a liquid fuel;

c) a conduit coupling each of the fuel cells to the fuel reservoir; and

d) an electrokinetic fuel pump coupled to the conduit, the electrokinetic fuel pump comprising a plurality of electrodes;

wherein the electrokinetic fuel pump moves the fuel from the fuel reservoir through the conduit to the plurality of fuel cells; and

the electrokinetic fuel pump electrodes do not deleteriously affect the performance of the membrane-electrode assembly.

24. A fuel cell system comprising:

a fuel reservoir for storing a fuel;

a conduit coupling the fuel reservoir to the fuel cell;

an electrokinetic fuel pump coupled to the conduit, the electrokinetic fuel pump comprising a plurality of electrodes; and

a fuel cell, the fuel cell further comprising

a reservoir; and

a membrane-electrode assembly having an anode;

a plurality of electrokinetic stirring pumps positioned inside the fuel cell for stirring the fuel inside the fuel cell, each electrokinetic stirring pump further comprising two outer electrodes and an inner electrode positioned between the two outer electrodes;

wherein the electrokinetic fuel pump moves fuel from the fuel reservoir through the conduit to the fuel cell; and

the electrokinetic fuel pump electrodes and the electrokinetic stirring pump electrodes do not deleteriously affect the performance of the membrane-electrode assembly.

25. The fuel cell system of claim 24 wherein the electric potential of the outer electrodes of the each of the plurality of electrokinetic stirring pumps is equal to the electric potential of the anode of the membrane-electrode assembly.

26. The fuel cell system of claim 24 wherein the plurality of electrokinetic stirring pumps are powered by a battery.

27. The fuel cell system of claim 24 wherein the plurality of electrokinetic stirring pumps are powered by an isolated power supply.

28. A method for generating electricity comprising pumping fuel with an electrokinetic fuel pump from a fuel reservoir into a fuel cell such that the fuel cell generates electricity.

29. A method for generating electricity comprising:

pumping fuel from a fuel reservoir to a fuel cell with an electrokinetic fuel pump;

passing the fuel through a membrane-electrode assembly in the fuel cell to generate an electric current.

30. The method of claim 29 further comprising:

monitoring the current produced by the fuel cell; and

controlling the rate of pumping fuel from the fuel reservoir based upon the current produced by the fuel cell.

31. The method of claim 29 further comprising stirring the fuel in the fuel cell with electrokinetic stirring pumps.

32. The method of claim 29 further comprising pumping reaction products generated at a cathode of the membrane-electrode assembly to the anode of the membrane-electrode assembly with an electrokinetic recirculation pump.