Cascade fuel inlet manifold for fuel cells

Abstract

Fuel is provided to an inlet ( 14 ) of a cascade region ( 15 ) which has a plurality of stages ( 17 - 23 ), each of which divides fuel flow evenly into a pair of corresponding slots ( 24 - 26 ). The flow is then spread across a floor surface ( 41 ) of a cascade exit header ( 40 ), the flow spreading into areas between the slots. The flow is then directed into an open cavity which is in fluid communication with the inlets of the fuel flow fields ( 12 ) of the fuel cells, reaching the fuel flow field inlets uniformly and simultaneously.

We claim:  
     
         1 . A fuel cell stack having an array of contiguous fuel cells, each fuel cell having a fuel flow field with a flow field inlet, said stack including a fuel inlet manifold system comprising: 
 a cascade region having a series of stages, each stage having a surface terminating in passages at opposite edges of said surface, each passage of each stage except the last in said series directing fuel to the surface of a next stage in said series, the passages of the last stage in said series directing fuel onto a cascade exit surface so that fuel is spread in dimensions not parallel with said passages; and    an open cavity disposed between said flow field inlets and said cascade exit surface.    
     
     
         2 . A fuel cell stack having an array of contiguous fuel cells, each fuel cell having a fuel flow field with a flow field inlet, comprising: 
 means for providing a flow of fuel from a source;    means for successively dividing the flow of fuel substantially equally into two substantially simultaneous flows, a number, n, of times, to provide n+1 flows, said number being at least three; and    means for spreading the fuel from said n+1 flows to provide a single, substantially uniform flow of fuel to said flow field inlets.    
     
     
         3 . A method of providing fuel to a fuel cell stack having an array of contiguous fuel cells, each fuel cell having a fuel flow field with a flow field inlet, said method comprising: 
 providing a flow of fuel from a source;    successively dividing the flow of fuel substantially equally into two substantially simultaneous flows, a number, n, of times, to provide n+1 flows, said number being at least three; and    spreading the fuel from said n+1 flows to provide a single, substantially uniform flow of fuel to said flow field inlets.