Fuel cell end unit with integrated heat exchanger

• US 7,070,874 B2
• Filed: 12/24/2002
• Issued: 07/04/2006
• Est. Priority Date: 12/24/2002
• Status: Expired due to Term

• Current Assignee: Fuelcell Energy Ltd.
• Original Assignee: Fuelcell Energy Ltd.
• Inventors: Patel, Pinakin, Blanchet, Scott
• Primary Examiner(s): Cantelmo, Gregg
• Application Number:
  US10/329,182
• Publication Number:
  US 20040121205A1
• Time in Patent Office: 1,288 Days
• Field of Search: 429/12, 429/26, 429/34, 429/38, 429/39, 165/176, 165/134.1, 165/145, 165/162
• US Class Current: 429/440
• CPC Class Codes: H01M 8/0247 characterised by the form characterised by a channel configuration H01M8/0258
• CPC Class Codes: H01M 8/0267 having heating or cooling means, e.g. heaters or coolant flow channels
• CPC Class Codes: H01M 8/04014 Heat exchange using gaseous fluids; Heat exchange by combustion of reactants
• CPC Class Codes: H01M 8/2457 with both reactants being gaseous or vaporised
• CPC Class Codes: H01M 8/2484 characterised by external manifolds
• CPC Class Codes: H01M 8/2485 Arrangements for sealing external manifolds; Arrangements for mounting external manifolds around a stack
• CPC Class Codes: Y02E 60/50 Fuel cells

Abstract

An end unit for a fuel cell stack is described that contains an integrated heat exchanger for superheating the fuel gas before delivery to the stack. Heat is transferred from the hot cathode outlet stream to the cool fuel inlet stream in a space adjacent the stack'"'"'s end plate. The end unit is designed as a hollow box forming the shell of the exchanger with the heat exchanger inside. The end unit has openings that allow fuel cell process gas to be taken directly from the stack without requiring piping or ductwork to be attached to thin manifolds. Separate chambers are provided for both the cathode outlet and anode outlet gas, thereby allowing all process connections to be made at one end of the stack. The end unit also features a current collection post that is separated from the end cell of the stack by a multitude of members which provide structural support for the end unit and act to more uniformly collect electrical current than would a single, large current post.

Claims

1. A fuel cell stack end unit for a fuel cell stack having a plurality of fuel cells stacked in a first direction, said end unit for stacking in said first direction adjacent an end fuel cell in said fuel cell stack, said end unit comprising:

an assembly having;

a first wall being adjacent said end cell when said end unit is stacked in said first direction in said fuel cell stack;

a second wall opposing said first wall;

a first side wall connecting said first and second walls;

a second side wall transverse to said first side wall and connecting said first and second walls;

a first inlet port receiving a first gas of said fuel cell stack when said end unit is stacked in said fuel cell stack; and

a second inlet port in said second side wall for receiving a second gas of said fuel cell stack when said end unit is stacked in said fuel cell stack;

said assembly conveying said first and second gases in heat exchange relationship and outputting said gases after heat is transferred from one gas to another when said end unit is stacked in said fuel stack;

a third side wall opposing said first side wall and connecting said first and second walls;

a fourth side wall opposing said second side wall and connecting said first and second walls;

a first outlet port in at least one of said first and third side walls for outputting said first gas after undergoing heat exchange in said assembly; and

a second outlet port in said fourth side wall for outputting said second gas after said second gas undergoes heat exchange in said assembly;

wherein said assembly further includes;

an interior wall extending between said first and second walls and said second and fourth side walls, said interior wall being spaced from said third side wall and forming with said first and second walls and said second and fourth side walls a chamber;

a third inlet port in said third side wall for receiving in said chamber a third gas of said fuel cell stack when said end unit is stacked in said fuel cell stack; and

a third outlet port in said second side wall for outputting said third gas after passage through said chamber.

2. A fuel cell stack end unit for a fuel cell stack having a plurality of fuel cells stacked in a first direction, said end unit for stacking in said first direction adjacent an end fuel cell in said fuel cell stack, said end unit comprising:

an assembly;

having a first wall being adjacent said end cell when said end unit is stacked in said first direction in said fuel cell stack, a second wall opposing said first wall;

a first side wall connecting said first and second walls;

a second side wall transverse to said first side wall and connecting said first and second walls;

a first inlet port receiving a first gas of said fuel cell stack when said end unit is stacked in said fuel cell stack; and

a second inlet port in said second side wall for receiving a second gas of said fuel cell stack when said end unit is stacked in said fuel cell stack;

said assembly conveying said first and second gases in heat exchange relationship and outputting said gases after heat is transferred from one gas to another when said end unit is stacked in said fuel stack;

a third side wall opposing said first side wall and connecting said first and second walls;

a fourth side wall opposing said second side wall and connecting said first and second walls;

a first outlet port in at least one of said first and third side walls for outputting said first gas after undergoing heat exchange in said assembly; and

a second outlet port in said fourth side wall for outputting said second gas after said second gas undergoes heat exchange in said assembly;

wherein said assembly further comprises;

a first unit for defining an enclosed gas flow path for said first gas; and

said first and second walls and said first, second, third and fourth side walls forming an enclosure of a second unit enclosing said first unit and defining a gas flow path for said second gas intersecting said first unit, wherein said first and second units act as a heat exchanger transferring heat from said second gas to said first gas.

3. A fuel cell stack end unit according to claim 2, further comprising a third unit disposed within said enclosure for receiving a third gas of said fuel cell stack when said end unit is stacked in said fuel cell stack.

4. A fuel cell stack end unit according to claim 3, wherein said assembly further includes:

an interior wall within said enclosure extending between said first and second walls and said second and fourth side walls, said interior wall being spaced from said third side wall and forming with said first and second walls and said second and fourth side walls said third unit;

a third inlet port in said third side wall for receiving in said third unit said third gas of said fuel cell stack when said end unit is stacked in said fuel cell stack; and

a third outlet port in said second side wall for outputting said third gas after passage through said third unit.

5. A fuel cell stack end unit according to claim 4, wherein said second gas flows into said second unit through said second inlet port and flows out of said second unit through said second outlet port, and wherein said second gas flows through said second unit in a direction transverse to the direction of flow of said first gas through said first unit.

6. A fuel cell stack end unit according to claim 5, wherein said first gas is fuel cell stack anode inlet gas, said second gas is fuel cell stack cathode outlet gas and said third gas is fuel cell stack anode outlet gas.

7. A fuel cell stack end unit according to claim 6, wherein said fuel cell cathode outlet gas is delivered from said fuel cell stack to said second inlet port by a cathode outlet gas manifold disposed on a side of said fuel cell stack.

8. A fuel cell stack end unit according to claim 5, wherein said first unit includes a plurality of tubes for receiving and carrying said first gas.

9. A fuel cell stack end unit according to claim 8, wherein said first gas is fuel cell stack anode inlet gas and said second gas is fuel cell stack cathode outlet gas.

10. A fuel cell stack end unit according to claim 9, wherein said third gas is fuel cell stack anode outlet gas.

11. A fuel cell stack end unit according to claim 10, wherein said plurality of tubes has a surface area transferring heat from said second gas flowing in said second unit to said first gas flowing in said tubes.

12. A fuel cell stack end unit according to claim 11, wherein all connections for delivering and removing process gases to and from said fuel cell stack are disposed in said end unit.

13. A fuel cell stack end unit according to claim 11, wherein said first unit further comprises an inlet chamber and an outlet chamber, said outlet chamber being connected to said inlet chamber by said plurality of tubes.

14. A fuel cell stack end unit according to claim 13, wherein said first unit further comprises:

a turn plenum, said turn plenum being connected by a first set of said plurality of tubes to said inlet chamber and being connected by a second set of said plurality of tubes to said outlet chamber.

15. A fuel cell stack end unit according to claim 14, wherein said fuel cell anode inlet gas flows into said inlet chamber, through said first set of said plurality of tubes, said turn plenum, and said second set of said plurality of tubes to said outlet chamber in a substantially U-shaped path.

16. A fuel cell stack end unit according to claim 14, wherein said outlet chamber of said first unit communicates said fuel cell anode inlet gas via said first outlet port to an anode inlet gas manifold disposed on a side of and providing anode gas to said fuel cell stack.

17. A fuel cell stack end unit according to claim 16, wherein said fuel cell stack anode outlet gas is communicated from said fuel cell stack to said third unit of said stack end unit by means of an anode outlet gas manifold disposed on a side of said fuel cell stack.

18. A fuel cell stack end unit according to claim 15, wherein said second unit has said second inlet port and said second outlet port.

19. A fuel cell stack end unit according to claim 18, wherein fuel cell stack cathode outlet gas enters said second unit through said second inlet port and exits said second unit through said second outlet port, said fuel cell cathode outlet gas flowing through said second unit in a direction substantially transverse to the direction of said first and second sets of said plurality of tubes in said first unit.

20. A fuel cell stack comprising:

a plurality of fuel cells stacked in a first direction and a fuel cell stack end unit stacked along said first direction adjacent an end fuel cell at each end of the stack, one of said fuel cell stack end units including an assembly having;

a first wall being adjacent said end cell;

a second wall opposing said first wall;

a first side wall connecting said first and second walls;

a second side wall transverse to said first side wall and connecting said first and second walls;

a first inlet port receiving a first gas of said fuel cell stack; and

a second inlet port in said second side wall for receiving a second gas of said fuel cell stack;

said assembly conveying said first and second gases in heat exchange relationship and outputting said gases after heat is transferred from one gas to another;

a third side wall opposing said first side wall and connecting said first and second walls;

a fourth side wall opposing said second side wall and connecting said first and second walls;

a first outlet port in at least one of said first and third side walls for outputting said first gas after said first gas undergoes heat exchange in said assembly; and

a second outlet port in said fourth side wall for outputting said second gas after said second gas undergoes heat exchange in said assembly; and

wherein said assembly further includes;

an interior wall extending between said first and second walls and said second and fourth side walls, said interior wall being spaced from said third side wall and forming with said first and second walls and said second and fourth side walls a chamber;

a third inlet port in said third side wall for receiving in said chamber a third gas of said fuel cell stack; and

a third outlet port in said second side wall for outputting said third gas after passage through said chamber.

21. A fuel cell stack comprising:

a plurality of fuel cells stacked in a first direction and a fuel cell stack end unit stacked along said first direction adjacent an end fuel cell at each end of the stack, one of said fuel cell stack end units including an assembly having;

a first wall being adjacent said end cell;

a second wall opposing said first wall;

a first side wall connecting said first and second walls;

a second side wall transverse to said first side wall and connecting said first and second walls;

a first inlet port receiving a first gas of said fuel cell stack; and

a second inlet port in said second side wall for receiving a second gas of said fuel cell stack;

said assembly conveying said first and second gases in heat exchange relationship and outputting said gases after heat is transferred from one gas to another;

a third side wall opposing said first side wall and connecting said first and second walls;

a fourth side wall opposing said second side wall and connecting said first and second walls;

a first outlet port in at least one of said first and third side walls for outputting said first gas after said first gas undergoes heat exchange in said assembly; and

a second outlet port in said fourth side wall for outputting said second gas after said second gas undergoes heat exchange in said assembly; and

wherein said assembly further comprises;

a first unit for defining an enclosed gas flow path for said first gas; and

said first and second walls and said first, second, third and fourth side walls forming an enclosure of a second unit enclosing said first unit and defining a gas flow path for said second gas intersecting said first unit, wherein said first and second units act as a heat exchanger transferring heat from said second gas to said first gas.

22. A fuel cell stack according to claim 21, wherein said assembly further comprises a third unit disposed within said enclosure for receiving a third gas of said fuel cell stack.

23. A fuel cell stack according to claim 21, wherein said first gas is fuel cell stack anode inlet gas.

24. A fuel cell stack according to claim 23, wherein said second gas is fuel cell stack cathode outlet gas.

25. A fuel cell stack according to claim 24, wherein said assembly further comprises a third unit disposed within said enclosure for receiving a third gas from said fuel cell stack.

26. A fuel cell stack according to claim 25, wherein said third gas is fuel cell anode outlet gas and said assembly further includes:

an interior wall within said enclosure extending between said first and second walls and said second and fourth side walls, said interior wall being spaced from said third side wall and forming with said first and second walls and said second and fourth side walls a third unit;

a third inlet port in said third side wall for receiving in said third unit said third gas; and

a third outlet port in said second side wall for outputting said third gas after passage through said third unit.

27. A fuel cell stack according to claim 26, wherein all connections for delivering and removing process gases to and from said fuel cell stack are disposed in said assembly.

28. A fuel cell stack according to claim 26, wherein said first unit comprises:

a plurality of tubes for receiving and carrying said first gas;

an inlet chamber and an outlet chamber, said outlet chamber being connected to said inlet chamber by said plurality of tubes.

29. A fuel cell stack according to claim 28, wherein said first unit further comprises:

a turn plenum, said turn plenum being connected by a first set of said plurality of tubes to said inlet chamber and being connected by a second set of said plurality of tubes to said outlet chamber.

30. A fuel cell stack according to claim 29, wherein said fuel cell anode inlet gas flows from said inlet chamber through said first set of said plurality of tubes, said turn plenum, and said second set of said plurality of tubes, to said outlet chamber in a U-shaped path.

31. A fuel cell stack according to claim 29, further comprising:

an anode gas inlet manifold disposed on one side of said stack, said anode gas inlet manifold receiving said fuel cell anode inlet gas from said outlet chamber of said first unit via said first outlet port and communicating said fuel cell anode inlet gas to said fuel cell stack.

32. A fuel cell stack according to claim 31, further comprising:

an anode gas outlet manifold disposed on a side of said stack opposite said anode gas inlet manifold, said anode gas outlet manifold communicating said fuel cell anode outlet gas from said fuel cell stack to said third unit via said third inlet port.

33. A fuel cell stack according to claim 32, wherein said second unit has said second inlet port and said second outlet port.

34. A fuel cell stack according to claim 33, wherein said fuel cell cathode outlet gas:

enters said second unit through said second inlet port;

flows through said second unit in a direction substantially transverse to the direction of said first and second sets of said plurality of tubes; and

exits said second unit through said second outlet port.

35. A fuel cell stack according to claim 34, further comprising a fuel cell cathode outlet gas manifold disposed on one side of said stack, said cathode gas outlet manifold delivering said fuel cell cathode outlet gas from said fuel cell stack to said second inlet port of said second unit.