Fuel cell and fuel cell coolant compositions

Abstract

This invention is directed to coolant compositions, particularly coolant compositions useful n fuel cells, and to fuel cells containing such coolant compositions. The coolant compositions or heat transfer fluids of this invention have and retain low electrical conductivity through extended periods of use. These coolant or heat transfer fluids are composed of a base composition and an additive package which imparts the property of retaining low electrical conductivity for extended periods of time. The base composition can be de-ionized water (DI water) alone or a mixture of DI water and a freezing point depressant of the types well-known in the art (e.g., propylene glycol). The additive package contains an organic corrosion inhibitor and a polymeric ion suppressant. The use of both components of the additive package is important.

1 . A method for removing heat generated in a fuel cell stack located in a loop by recirculating a heat transfer liquid through the loop, said loop comprising the fuel cell stack and a heat transfer removal means, said method comprising: 
 mixing deionized water with about 0.01% to about 5% by weight of an organic corrosion inhibitor to obtain a deionized water and organic corrosion inhibitor mixture;    suspending an ion exchange resin in said deionized water and corrosion inhibitor mixture to obtain said heat transfer liquid, wherein said ion exchange resin size is from about 0.1 micron to about 100 micron;    recirculating the heat transfer liquid in the loop through the fuel cell stack and the heat transfer removal means;    whereby the recirculating heat transfer liquid removes the heat generated in the fuel cell stack.    
   
   
       2 . A method for removing heat generated in the fuel cell stack of  claim 1  wherein the ion exchange resin is present in an amount of from about 0.01 percent to about 4 percent by weight of the heat transfer liquid.  
   
   
       3 . The heat transfer liquid of  claim 1  wherein the corrosion inhibitor is selected from the group consisting of azoles, aromatic hydroxy compounds and amines.  
   
   
       4 . The heat transfer liquid of  claim 3  wherein the azoles include benzotriazole, tolyriazole, methyl benzotriazoles, mercaptobenzoimidazole, and mercaptobenzothiazole.  
   
   
       5 . The heat transfer liquid of  claim 3  wherein the aromatic hydroxy compounds include salicylaldoxime, salicyl alcohol, methyl gallate, propyl gallate, octyl gallate, and dodecyl gallate.  
   
   
       6 . The heat transfer liquid of  claim 3  wherein the amines include alcohol amines.  
   
   
       7 . The heat transfer liquid of  claim 6  wherein the alcohol amines include monoethanol amine, diethanol amine, triethanol amine and morpholine.  
   
   
       8 . A method for removing heat generated in a fuel cell stack located in a loop by recirculating a heat transfer liquid through the loop, said loop comprising the fuel cell stack and a heat transfer removal means, said method comprising: 
 mixing deionized water and an organic freezing point depressant to obtain a deionized water and organic freezing point depressant mixture, wherein the deionized water is present in an amount of from about 10 to about 90% by volume of the deionized water and organic freezing point depressant mixture, and the organic freezing point depressant is present in an amount of from about 90 to about 10 percent by volume of the deionized water and freezing point depressant mixture;    mixing an organic corrosion inhibitor and an ion exchange resin to said deionized water and freezing point depressant mixture to obtain the heat transfer fluid, wherein the organic corrosion inhibitor is present in an amount of from about 0.01 to about 5 percent by weight of the heat transfer fluid, and the ion exchange resin is present as a suspension in the heat transfer fluid and in an amount of from about 0.01 to about 4 percent by weight of the heat transfer fluid;    recirculating the heat transfer liquid in the loop through the fuel cell stack and the heat transfer removal means;    whereby the recirculating heat transfer liquid removes the heat generated in the fuel cell stack.    
   
   
       9 . The heat transfer liquid of  claim 8  wherein the corrosion inhibitor is selected from the group consisting of azoles, aromatic hydroxy compounds and amines.  
   
   
       10 . The heat transfer liquid of  claim 9  wherein the azoles include benzotriazole, tolyriazole, methyl benzotriazoles, mercaptobenzoimidazole, and mercaptobenzothiazole.  
   
   
       11 . The heat transfer liquid of  claim 9  wherein the aromatic hydroxy compounds include salicylaldoxime, salicyl alcohol, methyl gallate, propyl gallate, octyl gallate, and dodecyl gallate.  
   
   
       12 . The heat transfer liquid of  claim 9  wherein the amines include alcohol amines.  
   
   
       13 . The heat transfer liquid of  claim 12  wherein the alcohol amines include monoethanol amine, diethanol amine, triethanol amine and morpholine.  
   
   
       14 . The heat transfer fluid of  claim 3  wherein the ion exchange resin has a size of from about 0.1 micron to about 100 micron.  
   
   
       15 . A method for reducing the rate of increase of the electrical conductivity of a heat transfer liquid circulated through a fuel cell stack comprising suspending in the liquid a mixture of two types of ion exchange particles; one having acid functionality and the other having base functionality.