Enhancement of proton exchange membrane fuel cell system by use of radial placement and integrated structural support system

• US 6,582,842 B1
• Filed: 11/09/2000
• Issued: 06/24/2003
• Est. Priority Date: 09/26/2000
• Status: Expired due to Fees

• Current Assignee: Texas A&M University System
• Original Assignee: Reliant Energy Power Systems, Inc.
• Inventors: King, George R.
• Primary Examiner(s): KALAFUT, STEPHEN J
• Application Number:
  US09/711,197
• Time in Patent Office: 957 Days
• Field of Search: 429/19, 429/20, 429/32, 429/38
• US Class Current: 429/423
• CPC Class Codes: H01M 8/0232 Metals or alloys
• CPC Class Codes: H01M 8/0245 in the form of layered or coated products
• CPC Class Codes: H01M 8/0254 corrugated or undulated
• CPC Class Codes: H01M 8/04089 of gaseous reactants
• CPC Class Codes: H01M 8/241 with solid or matrix-supported electrolytes
• CPC Class Codes: H01M 8/249 comprising two or more groupings of fuel cells, e.g. modular assemblies
• CPC Class Codes: Y02E 60/50 Fuel cells
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product
• CPC Class Codes: Y10T 428/12042 Porous component
• CPC Class Codes: Y10T 428/12382 Defined configuration of both thickness and nonthickness surface or angle therebetween [e.g., rounded corners, etc.]
• CPC Class Codes: Y10T 428/12479 Porous [e.g., foamed, spongy, cracked, etc.]
• CPC Class Codes: Y10T 428/12493 Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
• CPC Class Codes: Y10T 428/24694 Parallel corrugations
• CPC Class Codes: Y10T 428/249956 Void-containing component is inorganic

Abstract

An improved proton exchange membrane fuel cell system is provided for the economical and efficient production of electricity. The fuel cell system provides a plurality of fuel cell stacks that substantially surround a reformer assembly.

Claims

1. A fuel cell system comprising:

(a) a reformer subassembly;

(b) a plurality of fuel cell stacks, the plurality of fuel cell stacks so arranged as to substantially surround the reformer assembly, each fuel cell stack having a plurality of fuel inlet channels, each fuel inlet channel having a top and a bottom, and each fuel cell stack having an air inlet channel and an air and water outlet channel;

(c) an air supply header, the air supply header serving to connect a means for supplying air to each fuel cell stack with the air inlet channel of each fuel cell stack;

(d) an air and water return header, the air and water return header connected to the air and water outlet channel;

(e) a fuel supply header, the fuel supply header serving to connect the reformer subassembly to the top of the plurality of fuel inlet channels of each fuel cell stack; and

(f) a fuel discharge header, the fuel discharge header connected to the bottom of the fuel inlet channel of each fuel cell stack.

2. The fuel cell system according to claim 1, wherein the reformer subassembly is a partial oxidation, auto-thermal, closed-loop adiabatic or steam reformer.

3. The fuel cell system according to claim 1, wherein the air supply header further comprises a plurality of transition pieces and main supply header, each transition piece further comprising an orifice, each transition piece so situated as to connect the main supply header to the air supply channel of each fuel cell stack.

4. The fuel cell system according to claim 3, wherein each orifice of each transition piece is so sized as to be able to balance the pressure of a supply of air to each fuel cell stack.

5. The fuel cell system according to claim 1, wherein the fuel discharge header further comprises a bottom outlet valve, the bottom outlet valve acting to connect the fuel discharge header to the fuel outlet channel.

6. The fuel cell system according to claim 1, wherein the air and water outlet header further comprises a water removal device.

7. The fuel cell system of claim 1, wherein each fuel cell stack is radially placed around the reformer assembly.

8. The fuel cell system of claim 1, wherein each fuel cell stack is comprised of a node, wherein each node is comprised of a PEM fuel cell assembly.

9. The fuel cell system of claim 8, wherein each node of at least one fuel cell stack is comprised of a plurality of PEM fuel cell assemblies and wherein each PEM fuel assembly within each node is externally strapped.

10. The fuel cell system of claim 8, wherein each PEM fuel cell assembly comprises:

(a) an MEA, the MEA having two catalytic active layers, the MEA further having an anode side and a cathode side;

(b) a gas diffusion layer, the gas diffusion layer having a top face and a bottom face, the bottom face of the gas diffusion layer juxtaposed to the anode side of the MEA;

(c) a gas and liquid diffusion layer, the gas and liquid diffusion layer having a top face and a bottom face, the top face of the gas and liquid diffusion layer juxtaposed to the cathode side of the MEA;

(d) an anode gas flow field comprising a three-dimensional open-cell foamed structure suitable for gas diffusion, the anode gas flow field juxtaposed to the top face of the gas diffusion layer; and

(e) a cathode gas and liquid flow field comprising a three-dimensional open-cell foamed structure suitable for gas and liquid diffusion, the cathode gas and liquid flow field juxtaposed to the bottom face of the gas and liquid diffusion layer.

11. The fuel cell system according to claim 10, wherein the wherein the cathode gas and liquid flow field of the PEM fuel cell assembly has corrugations, the corrugations creating microchannels, the corrugations further having a pitch and a run, and the microchannels running parallel to the air supply channels.

12. The fuel cell system according to claim 11 wherein the pitch of the corrugations of the cathode gas and liquid flow field of the PEM fuel cell assembly is greater than or equal to ⅔

of the run of the corrugations.

13. The fuel cell system according to claim 10 wherein the anode gas flow field of the PEM fuel cell assembly comprises tin oxide, nickel, alloys of nickel, copper, alloys of copper, gold or alloys of gold.

14. The fuel cell system according to claim 10 wherein the cathode gas and liquid flow field of the PEM fuel cell assembly comprises tin oxide, nickel, alloys of nickel, copper, alloys of copper, gold, and alloys of gold.

15. The fuel cell system according to claim 10 wherein the anode gas flow field or the cathode gas and liquid flow field of the PEM fuel cell assembly are plated with tin oxide, gold, iridium, silver or copper.

16. The fuel cell system according to claim 10 wherein the MEA of the PEM fuel cell assembly further comprises a platinum or a platinum/ruthenium catalyst.

17. The fuel cell system according to claim 10 wherein the electrolyte of the PEM fuel cell assembly is a perfluorosulfonic acid membrane.

18. The fuel cell system according to claim 10 wherein the gas diffusion layer and the gas and liquid diffusion layer of the PEM fuel cell assembly comprise a fibrous layer.

19. A fuel cell system according to claim 1, wherein each fuel cell stack comprises:

(a) a first end plate and a second end plate, the second end plate being aligned with the first end plate;

(b) a plurality of fuel cell assemblies interposed between the first end plate and the second end plate, each fuel cell assembly comprising an open-cell foamed gas flow field, an open-cell foamed gas and liquid flow field, and an MEA; and

(c) an internal foil, the internal foil having an anode connection surface and a cathode connection surface, the anode connection surface being bonded to the gas flow field of a first fuel cell assembly and the cathode connection surface being bonded to the gas and liquid flow field of a second fuel cell assembly wherein the fuel cell assemblies are under compression.

20. The fuel cell stack system according to claim 19 wherein the first end plate or the second end plate of at least one fuel cell stack are made of polyetheretherketone.

21. The fuel cell stack system according to claim 19 wherein the first end plate or the second end plate of at least one fuel cell stack are substantially circular members.

22. The fuel cell system according to claim 19 wherein the compression on at least one fuel cell stack exerts less than 45 psi of compressive force.

23. The fuel cell system according to claim 22, wherein the weight of each individual fuel cell assembly is supported from the air supply header or the fuel supply header.

24. The fuel cell system according to claim 19 wherein the gas flow field and the gas and liquid flow field of at least one fuel cell assembly are comprised of tin oxide, nickel, alloys of nickel, copper, alloys of copper, gold, or alloys of gold.

25. The fuel cell system according to claim 19 wherein the gas flow field, the gas and liquid flow field, or the internal foil of at least one fuel cell assembly are plated with tin oxide or gold.

26. The fuel cell system according to claim 19 wherein the electrolyte foil of at least one fuel cell assembly is a fluorocarbon-based electrolyte.

27. The fuel cell system according to claim 19 wherein the MEA of at least one fuel cell assembly comprises a gas diffusion layer, the gas diffusion layer being located between the gas flow field and the electrolyte, and a gas and liquid diffusion layer, the gas and liquid diffusion layer being located between the gas and liquid flow field and the electrolyte.

28. The fuel cell system according to claim 27 wherein the MEA of at least one fuel cell assembly further comprises a platinum or a platinum/ruthenium catalyst.