Molded coolant plate assembly with integral reactant flow fields and thermal dam

1. An end-cooler assembly for a fuel cell comprising:

a cooler having a coolant tube array;

a composite material including flake graphite and hydrophobic polymer, the composite material surrounding the coolant tube array and providing a first side;

a reactant flow field formed in the first side;

a thermal dam embedded in and entirely surrounded by the composite material, the thermal dam arranged between the coolant tube array and the flow field; and

wherein the coolant tube array, composite material, flow field and thermal dam comprise a unitary, monolithic structure bound together by the composite material.

2. The end-cooler assembly according to claim 1 , comprising a pressure plate secured to a second side of the composite material that is opposite the first side.

3. The end-cooler assembly according to claim 2 , wherein a graphitized substrate is arranged between the pressure plate and the second side to provide compliance between the monolithic structure and the pressure plate.

4. The end-cooler assembly according to claim 3 , wherein a corrosion resistant tape is arranged about a perimeter of the pressure plate, and a corrosion resistant sealant is provided between the unitary, monolithic structure and the pressure plate near the perimeter and adjoining the tape.

5. The end-cooler assembly according to claim 1 , wherein the composite material includes 80-85% by weight flake graphite with the balance provided by one of a FEP, PFA or PTFE polymers.

6. The end-cooler assembly according to claim 1 , wherein the bottom of the flow field channel is spaced from the uppermost surface of the thermal dam by approximately 55 mils (1.4 mm).

7. The end-cooler assembly according to claim 1 , wherein the thermal dam includes a FEP film arranged between carbonized substrates.

8. The end-cooler assembly according to claim 7 , wherein the carbonized substrates are impregnated with a PTFE dispersion.

9. The end-cooler assembly according to claim 7 , wherein the carbonized substrates have an electrical areal resistance of about 0.016 ohm-in 2 (0.1 ohm-cm 2 ) providing a voltage drop across the thermal dam of about 0.010 V at a current density of 93 A/ft 2 (0.1 A/cm 2 ).

10. The end-cooler assembly according to claim 7 , wherein the thermal dam has a thermal conductivity of about 0.1 Btu/hr-ft-° F. (0.17 W/m-° K).

11. The end-cooler assembly according to claim 7 , wherein the thermal dam is about 40 mils (1.0 mm) thick.

12. A method of manufacturing an end-cooler assembly comprising the steps of:

a) depositing into a mold a first volume of a mixture of about 80-85% by weight flake graphite with the balance a hydrophobic polymer binder;

b) loading into the mold a coolant tube array onto the first volume;

c) depositing into the mold a powder of the mixture onto the coolant tube array;

d) loading into the mold a thermal dam comprising one of a carbonized substrate; or a FEP film sandwiched between two carbonized substrates onto the powder;

e) depositing into the mold a second volume of the mixture onto the thermal dam;

f) compressing the contents of the mold; and heating the contents of the mold above the melting point of the polymer and then cooling to below the solidifying point of the polymer the contents of the mold under compression; and

g) removing from the mold a unitary, monolithic structure comprising the mixture, the coolant tube array and the thermal dam.

13. The method according to claim 12 , wherein prior to performing step d), performing the step of manufacturing the thermal dam by laminating a FEP film between carbonized substrates.

14. The method according to claim 12 , comprising the step of forming a flow field in the unitary, monolithic structure on a first surface of the mixture near the thermal dam, and securing a pressure plate to a second surface of the mixture opposite the first surface.