Fuel cell with purge manifold
View Patent ↗A fuel cell includes an electrode assembly having an electrolyte between an anode and a cathode for generating an electric current and byproduct water. A porous plate is located adjacent to the electrode and includes reactant gas channels for delivering a reactant gas to the electrode assembly. A separator plate is located adjacent the porous plate such that the porous plate is between the electrode assembly and the separator plate. The separator plate includes a reactant gas inlet manifold and a reactant gas outlet manifold in fluid connection with the reactant gas channels, and a purge manifold in fluid connection with the porous plate such that limiting flow of the reactant gas from the reactant gas outlet manifold and opening the purge manifold under a pressure of the reactant gas in the reactant gas channels drives the byproduct water toward the purge manifold for removal from the fuel cell.
1. A method of managing water removal in a fuel cell comprising an electrode assembly for generating an electric current and byproduct water, a porous plate adjacent the electrode assembly, the porous plate including reactant gas channels for delivering a reactant gas to the electrode assembly, and a separator plate adjacent the porous plate such that the porous plate is between the electrode assembly and the separator plate, the separator plate including a reactant gas inlet manifold and a reactant gas outlet manifold in fluid connection with the reactant gas channels, and the separator plate including a purge manifold in fluid connection with the porous plate, the method comprising:
limiting flow of the reactant gas through the reactant gas outlet manifold;
allowing flow of the byproduct water through the purge manifold; and
establishing a pressure of the reactant gas in the reactant gas channels such that the reactant gas drives the byproduct water through pores in the porous plate toward the purge manifold for removal from the fuel cell, wherein establishing the pressure of the reactant gas includes establishing a pressure that is greater than a capillary pressure in the pores of the porous plate.
2. The method as recited in claim 1 , wherein limiting flow of the reactant gas through the reactant gas outlet manifold includes at least partially closing an outlet valve associated with the reactant gas outlet manifold.
3. The method as recited in claim 1 , wherein allowing flow of the byproduct water through the purge manifold includes at least partially opening a purge valve associated with the purge manifold.
4. The method as recited in claim 1 , wherein establishing the pressure of the reactant gas includes establishing an open state of an inlet valve associated with the reactant gas inlet manifold to permit a flow of the reactant gas from the reactant gas inlet manifold into the reactant gas channels of the porous plate.
5. The method as recited in claim 1 , wherein allowing flow of the byproduct water through the purge manifold is in conjunction with shutdown of the fuel cell.
6. The method as recited in claim 1 , including selecting the pressure of the reactant gas to be within the range of 10-200 kPag.
7. The method as recited in claim 6 , including selecting the pressure of the reactant gas to be within the range of 100-200 kPag.
8. The method as recited in claim 1 wherein the pores of the porous plate have an average pore radius within the range of 0.1-10 micrometers.
9. The method as recited in claim 1 wherein the porous plate has a porosity within the range of 5-50%.
10. The method as recited in claim 1 wherein the reactant gas channels are formed in a first side of the porous plate adjacent to the electrode assembly and the purge manifold is in fluid connection with the porous plate through byproduct water channels formed adjacent to a second side of the porous plate opposite to the first side of the porous plate.
11. The method as recited in claim 1 wherein establishing the pressure of the reactant gas in the reactant gas channels such that the reactant gas drives the byproduct water through the pores of the porous plate toward the purge manifold for removal from the fuel cell includes establishing the pressure of the reactant gas in the reactant gas channels such that the reactant gas drives the byproduct water through a thickness of the porous plate.
12. The method as recited in claim 1 wherein the purge manifold is below the reactant gas inlet manifold when the separator plate is vertically oriented.
13. The method as recited in claim 1 wherein the purge manifold is located in a lower half of the separator plate when the separator plate is vertically oriented.
14. The method as recited in claim 1 wherein the separator plate includes the reactant gas inlet manifold, the reactant gas outlet manifold, the purge manifold, a second reactant gas inlet manifold, a second reactant gas outlet manifold, a coolant inlet manifold, and a coolant outlet manifold.