Fuel cell end unit with integrated heat exchanger

• US 20040121205A1
• Filed: 12/24/2002
• Published: 06/24/2004
• Est. Priority Date: 12/24/2002
• Status: Active Grant

• Current Assignee: Fuelcell Energy Ltd.
• Original Assignee: Fuelcell Energy Ltd.
• Inventors: Blanchet, Scott
• Granted Patent: US 7,070,874 B2
• Time in Patent Office: Days
• US Class Current: 429/26
• 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, comprising:

an assembly adapted to receive first and second gases, to convey said first and second gases in heat exchange relationship and to output said gases after heat is transferred from one gas to another.

2. A fuel cell stack end unit according to claim 1, wherein said assembly comprises:

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

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 adapted to transfer heat from said second gas to said first gas.

3. A fuel cell stack end unit according to claim 2, wherein said first unit includes a plurality of tubes for receiving and carrying said first gas and said second unit comprises an enclosure in which said plurality of tubes are disposed.

4. A fuel cell stack end unit according to claim 3, wherein said plurality of tubes has a surface area adapted to transfer heat from said second gas flowing in said second unit to said first gas flowing in said tubes.

5. A fuel cell stack end unit according to claim 4, wherein said second unit is in the form of a hollow box forming said enclosure, said hollow box defining exterior walls of said heat exchanger.

6. A fuel cell stack end unit according to claim 5, further comprising a third unit disposed within said hollow box and adapted to receive a third gas.

7. A fuel cell stack end unit according to claim 6, wherein said hollow box has first and second opposing exterior walls and said second unit further comprises an inlet port disposed in said first exterior wall of said hollow box and an outlet port disposed in said second exterior wall of said hollow box.

8. A fuel cell stack end unit according to claim 7, wherein said second gas flows into said second unit through said inlet port and flows out of said second unit through said outlet port, and wherein said second gas flows through said second unit in a direction transverse to the direction of said plurality of tubes in said first unit.

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 fuel cell cathode outlet gas is delivered from said fuel cell stack to said inlet port of said second unit by a cathode outlet gas manifold disposed on a side of said fuel cell stack.

11. A fuel cell stack end unit according to claim 4, wherein said first gas is fuel cell stack anode inlet gas.

12. A fuel cell stack end unit according to claim 11, wherein said second gas is fuel cell stack cathode outlet gas.

13. A fuel cell stack end unit according to claim 12, further comprising a third unit adapted to receive a third gas from said fuel cell stack.

14. A fuel cell stack end unit according to claim 13, wherein said third unit is disposed within said second unit and wherein said third gas is fuel cell anode outlet gas.

15. A fuel cell stack end unit according to claim 14, wherein all connections for delivering and removing process gases to and from said fuel cell stack are disposed in said end unit.

16. A fuel cell stack end unit according to claim 14, 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.

17. A fuel cell stack end unit according to claim 16, 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.

18. A fuel cell stack end unit according to claim 17, 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.

19. A fuel cell stack end unit according to claim 17, wherein said outlet chamber of said first unit communicates said fuel cell anode inlet gas to an anode inlet gas manifold disposed on a side of and providing anode gas to said fuel cell stack.

20. A fuel cell stack end unit according to claim 19, 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.

21. A fuel cell stack end unit according to claim 18, wherein said second unit further comprises an inlet port formed on one side of said enclosure and an outlet port formed on a side of said enclosure opposite said one side.

22. A fuel cell stack end unit according to claim 21, wherein fuel cell stack cathode outlet gas enters said second unit through said inlet port and exits said second unit through said 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.

23. A fuel cell stack comprising a plurality of fuel cells and a fuel cell stack end unit disposed at each end of the stack, one of said fuel cell stack end units including an assembly adapted to receive first and second gases, to convey said first and second gases in heat exchange relationship and to output said gases after heat is transferred from one gas to another.

24. A fuel cell stack according to claim 23, wherein said heat exchanger is adapted to superheat fuel gas before delivery to said stack.

25. A fuel cell stack according to claim 23, wherein said assembly comprises:

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

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 adapted to transfer heat from said second gas to said first gas.

26. A fuel cell stack according to claim 25, wherein said first unit includes a plurality of tubes for receiving and carrying said first gas and said second unit comprises an enclosure in which said plurality of tubes are disposed.

27. A fuel cell stack according to claim 26, wherein said plurality of tubes has a surface area adapted to transfer heat from said second gas flowing in said second unit to said first gas flowing in said plurality of tubes.

28. A fuel cell stack according to claim 27, wherein said fuel cell end unit is in the form of a hollow box forming said enclosure, said hollow box defining exterior walls of said heat exchanger.

29. A fuel cell stack according to claim 28, further comprising a third unit disposed within said hollow box, said third unit being adapted to receive a third gas.

30. A fuel cell stack according to claim 27, wherein said first gas is fuel cell stack anode inlet gas.

31. A fuel cell stack according to claim 30, wherein said second gas is fuel cell stack cathode outlet gas.

32. A fuel cell stack according to claim 31, wherein said assembly further comprises a third unit adapted to receive a third gas from said fuel cell stack.

33. A fuel cell stack according to claim 32, wherein said third unit is disposed within said second unit and wherein said third gas is fuel cell anode outlet gas.

34. A fuel cell stack according to claim 32, wherein all connections for delivering and removing process gases to and from said fuel cell stack are disposed in said assembly.

35. A fuel cell stack according to claim 34, 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.

36. A fuel cell stack according to claim 35, 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.

37. A fuel cell stack according to claim 36, 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.

38. A fuel cell stack according to claim 36, 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 and communicating said fuel cell anode inlet gas to said fuel cell stack.

39. A fuel cell stack according to claim 38, 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.

40. A fuel cell stack according to claim 39, wherein said second unit further comprises an inlet port formed on one side of said enclosure and an outlet port formed on a side of said enclosure opposite said one side.

41. A fuel cell stack according to claim 40, wherein said fuel cell cathode outlet gas:

enters said second unit through said 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 outlet port.

42. A fuel cell stack according to claim 41, 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 inlet port of said second unit.

43. An end unit for attachment between one end of a fuel cell stack and a current collection post, said end unit comprising a structure adapted to restrict electrical current flow from said fuel cell stack to said current collection post.

44. An end unit according to claim 43, further comprising a first surface in electrical contact with said fuel cell stack and a second surface in electrical contact with said current collection post, said structure being in electrical contact with said first and second surfaces.

45. An end unit according to claim 44, wherein said structure comprises a plurality of members, said members connecting said first and second surfaces of said end unit.

46. An end unit according to claim 45, wherein said members of said structure are electrically conductive.

47. An end unit according to claim 46, wherein said members are disposed at uniformly spaced intervals between said first and second surfaces.

48. An end unit according to claim 47, wherein each of said members is a cylindrical post.

49. An end unit for attachment to a fuel cell stack, said end unit separating a current collection post from the fuel cell stack, said end unit comprising a structure adapted to restrict electrical current flow from said fuel cell stack to said current collection post;

wherein said structure is further adapted to receive first and second gases, to convey said first and second gases in heat exchange relationship and to output said gases after heat is transferred from one gas to another.

50. A fuel cell stack comprising:

a plurality of fuel cells;

a current collection post disposed at one end of said fuel cell stack; and

an end unit for attachment to one end of said plurality of fuel cells and separating said current collection post from said plurality of fuel cells, said end unit comprising a structure adapted to restrict electrical current flow from said plurality of fuel cells to said current collection post,

wherein said structure is further adapted to receive first and second gases, to convey said first and second gases in heat exchange relationship and to output said gases after heat is transferred from one gas to another.

51. A fuel cell stack comprising:

a plurality of fuel cells;

a current collection post disposed at one end of said fuel cell stack; and

an end unit for attachment to one end of said plurality of fuel cells and separating said current collection post from said plurality of fuel cells, said end unit comprising a structure adapted to restrict electrical current flow from said plurality of fuel cells to said current collection post.