Fuel cell stack assembly and method of operating the same

Abstract

A fuel cell stack assembly and method of operating the same are provided. The assembly includes a fuel cell stack column and side baffles disposed on opposing sides of the column. The side baffles and the fuel cell stack may have substantially the same coefficient of thermal expansion at room temperature. The side baffles may have a laminate structure in which one or more channels are formed.

What is claimed is: 
     
         1 . A fuel cell stack assembly comprising:
 a fuel cell stack column; and   side baffles disposed on opposing sides of the column,   wherein:   the side baffles have a first coefficient of thermal expansion (CTE) at room temperature,   the column has a second CTE at room temperature, and   at least one of:
 (a) the first CTE is within +/−20% of the second CTE; or 
 (b) the side baffles each comprising first and second baffle plates that are laminated to one another and comprise different ceramic materials. 
   
     
     
         2 . The fuel cell stack assembly of  claim 1 , wherein the first CTE is within +/−20% of the second CTE. 
     
     
         3 . The fuel cell stack assembly of  claim 2 , wherein:
 the side baffles each comprise first and second baffle plates that are connected to one another at edges thereof and have substantially the same size and shape;   the first baffle plates have a third CTE at room temperature that is greater than the second CTE; and   the second baffle plates have a fourth CTE at room temperature that is less than the second CTE.   
     
     
         4 . The fuel cell stack assembly of  claim 3 , wherein the average of the third CTE and the fourth CTE is substantially equal to the second CTE. 
     
     
         5 . The fuel cell stack assembly of  claim 2 , wherein:
 the side baffles each comprise first and second baffle plates that are connected to one another at edges thereof and that have different lengths;   the first baffle plates have a third CTE at room temperature that is greater than the second CTE; and   the second baffle plates have a fourth CTE at room temperature that is less than the second CTE.   
     
     
         6 . The fuel cell stack assembly of  claim 5 , wherein the average of the third CTE and the fourth CTE is not substantially equal to the second CTE. 
     
     
         7 . The fuel cell stack assembly of  claim 5 , wherein,
 the column has a length C, and   a length A of the first baffle plate and length B of the second baffle plate satisfy the following equation:   
       
         
           
             
               
                 second 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 CTE 
                 * 
                 Length 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 C 
               
               = 
               
                 
                   third 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   CTE 
                   * 
                   Length 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   A 
                 
                 + 
                 
                   fourth 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   CTE 
                   * 
                   Length 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   
                     B 
                     . 
                   
                 
               
             
           
         
       
     
     
         8 . The fuel cell stack assembly of  claim 2 , wherein the first CTE ranges from about 8.7 to about 10.7 at room temperature and the first CTE is within +/−10% of the second CTE. 
     
     
         9 . The fuel cell stack assembly of  claim 2 , wherein the first CTE and the second CTE are both about 9.7. 
     
     
         10 . The fuel cell stack assembly of  claim 2 , wherein the side baffles comprise an alumina-titania mixture having the first CTE. 
     
     
         11 . The fuel cell stack assembly of  claim 2 , further comprising:
 a compression assembly disposed on a first end of the column; and   a lower block disposed on an opposing second end of the column,   wherein the side baffles connect the compression assembly and the lower block.   
     
     
         12 . The fuel cell stack assembly of  claim 11 , wherein the compression assembly is configured to apply a first load to the column at room temperature and is configured to apply a second load to the column at about 650° C., the first and second loads being substantially the same. 
     
     
         13 . The fuel cell stack assembly of  claim 2 , wherein:
 the column comprises solid oxide fuel cells; and   the side baffles each comprise the first and the second baffle plates that are laminated to one another and comprise the different ceramic materials.   
     
     
         14 . The fuel cell stack assembly of  claim 1 , wherein the side baffles each comprise the first and the second baffle plates that are laminated to one another and comprise the different ceramic materials. 
     
     
         15 . The fuel cell stack assembly of  claim 14 , wherein:
 the first baffle plates are disposed closer to the column than the second baffle plates; and   the first baffle plates have a higher dielectric strength than the second baffle plates.   
     
     
         16 . The fuel cell stack assembly of  claim 14 , wherein the first and second baffle plates have different thermal conductivities. 
     
     
         17 . The fuel cell stack assembly of  claim 15 , wherein the side baffles each comprise a third baffle plate laminated to the first or second baffle plates. 
     
     
         18 . The fuel cell stack assembly of  claim 14 , further comprising:
 a compression assembly disposed on a first end of the column; and   a lower block disposed on an opposing second end of the column, wherein the side baffles connect the compression assembly and the lower block.   
     
     
         19 . The fuel cell stack assembly of  claim 18 , wherein:
 the compression assembly applies a compressive force to the column;   the side baffles further comprise third baffle plates that are laminated to the second baffle plates, the second baffle plates being disposed between the first and third baffle plates, wherein at least one of the second baffle plates comprises channels that extend in a direction perpendicular to a stacking direction of fuel cells of the column, and the channels extend from the column to an outer surface of the corresponding side baffle; and   bypass electrodes disposed in the channels and configured to electrically bypass one or more selected fuel cells of the column.   
     
     
         20 . The fuel cell stack assembly of  claim 18 , wherein:
 the compression assembly applies a compressive force to the column;   the side baffles further comprise third baffle plates that are laminated to the second baffle plates, the second baffle plates being disposed between the first and third baffle plates, wherein at least one of the second baffle plates comprises channels that extend in a direction perpendicular to a stacking direction of fuel cells of the column, and the channels extend from the column to an outer surface of the corresponding side baffle; and   at least one of sensors and electrical leads disposed in the channels.