Fuel cell components, stacks and modular fuel cell systems

1. A proton exchange membrane fuel cell power module comprising:

(a) a cylindrical housing having an interior surface;

(b) a fuel cell stack contained within said cylindrical housing, said fuel cell stack comprising a plurality of fuel cells interposed between a pair of compression end-plates, each of said fuel cells comprising an anode and an anode flow field plate, a cathode and a cathode flow field plate, and a proton conducting membrane electrolyte interposed between said anode and said cathode;

(c) a humidifier contained within said cylindrical housing; and

(d) an air supply configured to direct air to said plurality of fuel cell cathode flow field plates via said humidifier and via a plenum defined by a space between said fuel cell stack and said interior surface of said cylindrical housing.

2. The proton exchange membrane fuel cell power module of claim 1 , wherein said humidifier is a bubbler humidifier.

3. The proton exchange membrane fuel cell power module of claim 1 , wherein said humidifier comprises a reservoir containing water, wherein said reservoir is located within said plenum.

4. The proton exchange membrane fuel cell power module of claim 3 wherein said fuel cell stack is cylindrical.

5. The proton exchange membrane fuel cell power module of claim 4 , wherein said plenum serves as an oxidant supply manifold, and wherein said air supply is configured to direct air into said plenum and in contact with said water in said reservoir such that said air is humidified and then

(i) enters said plurality of cathode flow field plates;

(ii) flows substantially radially through said plurality of cathode flow field plates; and

(iii) exits said fuel cell stack via a central oxidant exhaust manifold.

6. The proton exchange membrane fuel cell power module of claim 4 , wherein said plenum serves as an oxidant supply manifold and is divided by a baffle, and wherein said air supply is configured to direct air into said plenum such that said air

(i) flows between said interior surface of said cylindrical housing and an outer wall of said baffle in a first substantially axial direction;

(ii) contacts said water in said reservoir such that said air is humidified;

(iii) flows between an inner wall of said baffle and said fuel cell stack in a second substantially axial direction, wherein said second substantially axial direction is opposite to said first substantially axial direction;

(iv) flows substantially radially through said plurality of cathode flow field plates; and

(v) exits said fuel cell stack via a central oxidant exhaust manifold.

7. The proton exchange membrane fuel cell power module of claim 4 , further comprising a layer of diffusive media at least partially submerged in said water in said reservoir.

8. The proton exchange membrane fuel cell power module of claim 5 , further comprising a water collection system for recovering water from air flowing; in said oxidant exhaust manifold and directing said recovered water to said reservoir.

9. The proton exchange membrane fuel cell power module of claim 4 , further comprising:

(e) a plurality of coolant pathways, each of said pathways disposed between an adjacent pair of said plurality of fuel cells, wherein said coolant pathways are fluidly connected to said reservoir; and

(f) a coolant circulation system configured to circulate said water from said reservoir through said coolant pathways.

10. The proton exchange membrane fuel cell power module of claim 9 , wherein said humidifier further comprises a plurality of nozzles fluidly connected to receive said water exiting said coolant pathways, wherein said coolant circulation system is configured to spray water exiting said coolant pathways into said plenum via said plurality of nozzles to humidify air flowing through said plenum.

11. The proton exchange membrane fuel cell power module of claim 1 , further comprising:

(e) a fuel inlet manifold comprising a plurality of aligned first openings formed in each of said plurality of fuel cells for directing a fuel supply stream to each of said plurality of anode flow field plates; and

(f) a fuel outlet manifold comprising a plurality of aligned second openings formed in each of said plurality of fuel cells for discharging a fuel exhaust stream from each of said plurality of anode flow field plates.

12. The proton exchange membrane fuel cell power module of claim 3 wherein said fuel cell stack is hexagonal.

13. The proton exchange membrane fuel cell power module of claim 12 , wherein said plenum serves as an oxidant supply manifold, and wherein said air supply is configured to direct air into said plenum and in contact with said water in said reservoir such that said air is humidified and then

(i) enters said plurality of cathode flow field plates;

(ii) flows substantially radially through said plurality of cathode flow field plates; and

(iii) exits said fuel cell stack via a central oxidant exhaust manifold.

14. The proton exchange membrane fuel cell power module of claim 12 , wherein said plenum serves as an oxidant supply manifold and is divided by a baffle, and wherein said air supply is configured to direct air into said plenum such that said air

(i) flows between said interior surface of said cylindrical housing and an outer wall of said baffle in a first substantially axial direction;

(ii) contacts said water in said reservoir such that said air is humidified;

(iii) flows between an inner wall of said baffle and said fuel cell stack in a second substantially axial direction, wherein said second substantially axial direction is opposite to said first substantially axial direction;

(iv) flows substantially radially through said plurality of cathode flow field plates; and

(v) exits said fuel cell stack via a central oxidant exhaust manifold.

15. The proton exchange membrane fuel cell power module of claim 12 , further comprising a layer of diffusive media at least partially submerged in said water in said reservoir.

16. The proton exchange membrane fuel cell power module of claim 13 , further comprising a water collection system for recovering water from air flowing in said oxidant exhaust manifold and directing said recovered water to said reservoir.

17. The proton exchange membrane fuel cell power module of claim 12 , further comprising:

(e) a plurality of coolant pathways, each of said pathways disposed between an adjacent pair of said plurality of fuel cells, wherein said coolant pathways are fluidly connected to said reservoir; and

(f) a coolant circulation system configured to circulate said water from said reservoir through said coolant pathways.

18. The proton exchange membrane fuel cell power module of claim 17 , wherein said humidifier further comprises a plurality of nozzles fluidly connected to receive said water exiting said coolant pathways, wherein said coolant circulation system is configured to spray water exiting said coolant pathways into said plenum via said plurality of nozzles to humidify air flowing through said plenum.

19. The proton exchange membrane fuel cell power module of claim 12 , wherein at least one of said anode, said anode flow field plate, said cathode and said cathode flow field plate comprises sheet material shaped in the form selected from a group consisting of a triangle, a square, a rectangle, a parallelogram and a half-hexagon, wherein said forms are capable of being fitted together into a substantially hexagonal assembly.

20. The proton exchange membrane fuel cell power module of claim 12 , wherein said hexagonal fuel cell stack is formed by a plurality of fuel cell sub-stacks shaped such that when assembled within said cylindrical housing, said fuel cell sub-stacks together constitute said hexagonal fuel cell stack.