Mid-combustion fluid injection for NOx reduction

Abstract

A method of reducing the amount of NOx produced by a diesel engine, by injecting a heat sink fluid into the combustion chamber after commencement of a combustion cycle, and before the natural cessation of NOx production during the same combustion cycle, thereby altering the NOx formation cycle associated with the combustion cycle.

I claim:  
     
         1 . A method for reducing the formation of NOx in a diesel engine, comprising: 
 injecting fuel to begin a cycle of combustion of said fuel and an associated cycle of formation of NOx in a cylinder of a diesel engine; and    injecting a heat sink fluid into said cylinder, said heat sink fluid injection beginning after said beginning of said cycle of combustion of said fuel, said heat sink fluid injection beginning before cessation of said associated cycle of said NOx formation in said cylinder.    
     
     
         2 . The method recited in  claim 1 , wherein said heat sink fluid comprises air.  
     
     
         3 . The method recited in  claim 1 , wherein said heat sink fluid comprises nitrogen.  
     
     
         4 . The method recited in  claim 1 , wherein said heat sink fluid comprises water.  
     
     
         5 . The method recited in  claim 1 , further comprising ceasing said injection of said heat sink fluid before cessation of said cycle of combustion of said fuel.  
     
     
         6 . The method recited in  claim 1 , further comprising repeating said injection of said heat sink fluid during selected said combustion cycles in said cylinder.  
     
     
         7 . The method recited in  claim 6 , further comprising omitting said injection of said heat sink fluid during at least some said combustion cycles.  
     
     
         8 . A method for reducing the formation of NOx in a diesel engine, comprising: 
 injecting fuel to begin a cycle of combustion of said fuel and an associated cycle of formation of NOx in a cylinder of a diesel engine;    beginning injection of a heat sink fluid into said cylinder, after said beginning of said cycle of combustion of said fuel and before cessation of said associated cycle of said NOx formation in said cylinder; and    ceasing said injection of said heat sink fluid before cessation of said cycle of combustion of said fuel.    
     
     
         9 . The method recited in  claim 8 , wherein said heat sink fluid comprises air.  
     
     
         10 . The method recited in  claim 8 , wherein said heat sink fluid comprises nitrogen.  
     
     
         11 . The method recited in  claim 8 , wherein said heat sink fluid comprises water.  
     
     
         12 . The method recited in  claim 8 , further comprising repeating said injection of said heat sink fluid during selected said combustion cycles in said cylinder.  
     
     
         13 . The method recited in  claim 12 , further comprising omitting said injection of said heat sink fluid during at least some said combustion cycles.  
     
     
         14 . A method for reducing the formation of NOx in a diesel engine, comprising: 
 repeatedly injecting fuel to begin a plurality of cycles of combustion of said fuel and a plurality of associated cycles of formation of NOx in a cylinder of a diesel engine; and    repeatedly injecting a heat sink fluid into said cylinder, after each said beginning of selected said cycles of combustion of said fuel and before cessation of associated said cycles of said NOx formation in said cylinder;    wherein each said injection of said heat sink fluid ceases before cessation of said associated cycle of combustion of said fuel.    
     
     
         15 . The method recited in  claim 14 , wherein said heat sink fluid comprises air.  
     
     
         16 . The method recited in  claim 14 , wherein said heat sink fluid comprises nitrogen.  
     
     
         17 . The method recited in  claim 14 , wherein said heat sink fluid comprises water.  
     
     
         18 . The method recited in  claim 14 , further comprising omitting said injection of said heat sink fluid during at least some said combustion cycles.