Fuel cell stack with an integral ejector for reactant gas recirculation

DETAILED DESCRIPTION Having thus described a typical embodiment of my invention, that which I claim as new and desire to secure by letters Patent of the United States is: 1.
In a fuel cell stack comprising a plurality of fuel cells each including a fuel electrode and an oxidant electrode spaced apart defining an electrolyte compartment therebetween, means constructed and arranged with said cells to define a reactant gas space on the nonelectrolyte side of each electrode, said reactant gas spaces including a fuel gas space on the nonelectrolyte side of each fuel electrode and an oxidant gas space on the nonelectrolyte side of each oxidant electrode, each of said gas spaces having an inlet and an outlet, the improvement to said stack comprising: an ejector for delivering and recirculating one of said reactant gases through said cells, said ejector constructed and arranged to be integral with and in heat exchange relationship with the cells of said stack, said ejector including primary inlet means, secondary inlet means, and outlet means; first conduit means connected to said ejector primary inlet means for delivering preheated reactant gas into said ejector primary inlet means; second conduit means connecting said ejector outlet means to said inlets of said recirculating reactant gas spaces; and third conduit means connecting said recirculating reactant gas space outlets with said ejector secondary inlet means, said secondary inlet means including means for establishing the recirculation rate of reactant gas through said ejector.
2.
The improvement to said stack according to claim 1 wherein said recirculating reactant gas is the oxidant.
3.
The improvement to said stack according to claim 1 wherein said first conduit means is in heat exchange relationship with the cells in said stack for preheating the reactant gas using stack waste heat prior to its delivery into said ejector.
4.
The improvement to said stack according to claim 1 wherein said stack includes end plate means adjacent the last cell of said stack and in heat exchange relationship therewith, said ejector being an integral part of said end plate means