Fine particle dispersion compositions and uses thereof

Abstract

The present invention relates to dispersion compositions comprising synthetic oils or other heat transfer fluids and fine particles. The compositions also comprise at least one dispersant. The dispersion compositions have improved thermal conductivity properties, which may translate to improved energy efficiency performance in a variety of heat transfer applications. Such applications include vapor compression air conditioning and refrigeration systems of all types, secondary heat transfer fluids, and other heating or cooling fluid applications.

1 . A dispersion composition, said composition comprising fine particles of metal or metal oxide dispersed in a synthetic oil medium and optionally, at least one dispersant.  
   
   
       2 . The composition of  claim 1  wherein said metal oxide is selected from the group consisting of magnesium oxide, silicon dioxide, titanium dioxide, iron oxide, copper oxide, zinc oxide, zirconium oxide, stannic oxide, and cerium oxide.  
   
   
       3 . The composition of  claim 1  wherein said metal is selected from the group consisting of copper and silver.  
   
   
       4 . The composition of  claim 1  wherein said metal oxide is iron oxide and said synthetic oil is selected from the group consisting of polyol ester and polyalklyene glycol.  
   
   
       5 . The composition of  claim 4  wherein said iron oxide particles are present in an amount not greater than about 50 weight percent.  
   
   
       6 . The composition of  claim 4  wherein said iron oxide particles are present in an amount not greater than about 25 weight percent.  
   
   
       7 . The composition of  claim 4  wherein said iron oxide particles are present in an amount not greater than about 6 weight percent.  
   
   
       8 . The composition of  claim 5 ,  6 , or  7  wherein said dispersant is present and is selected from the group consisting of anionic dispersants, non-ionic dispersants, and combinations thereof.  
   
   
       9 . The composition of  claim 5 ,  6 , or  7  wherein at least one dispersant is present and is selected from the group consisting of sulfosuccinates, alkoxylated polyaromatics, 12-hydroxystearic acid, polyhydroxystearic acid and combinations thereof.  
   
   
       10 . The composition of  claim 4  wherein said dispersant is present in said composition at from about 1 weight percent to about 6 weight percent.  
   
   
       11 . The composition of  claim 4  wherein said dispersant is present in said composition at from about 1 weight percent to about 4 weight percent.  
   
   
       12 . The composition of  claim 1  wherein said metal oxide particles are iron oxide particles having a median particle size of about 30 nanometers or less, and wherein said dispersant is selected from the group consisting of sulfosuccinates, alkoxylated polyaromatics, 12-hydroxystearic acid, polyhydroxystearic acid and mixtures thereof.  
   
   
       13 . A synthetic oil composition comprising fine particles of metal or metal oxide, and at least one dispersant, and having enhanced thermal conductivity based on the presence of the fine particles.  
   
   
       14 . A method for preparing a dispersion composition comprised of fine particles of metal or metal oxide, synthetic oil and at least one dispersant, said method comprising combining said at least one dispersant with said synthetic oil, combining said fine particles of metal or metal oxide with the dispersant and synthetic oil combination to form a slurry, and providing the resultant slurry to a milling device to produce said dispersion composition.  
   
   
       15 . The method of  claim 14 , said method further comprising providing the produced dispersion composition to a milling device until a median particle size of less than about 30 nanometers is obtained to produce a synthetic oil having enhanced thermal conductivity.  
   
   
       16 . The method of  claim 14  wherein said milling device is a ball mill or a media mill.  
   
   
       17 . The method of  claim 14  wherein said milling device is a media mill.  
   
   
       18 . The method of  claim 14  wherein said milling device is a media mill and wherein said milling device utilizes 0.2 millimeter diameter grinding media.  
   
   
       19 . The method of  claim 14  wherein said particles are a metal oxide selected from the group consisting of magnesium oxide, silicon dioxide, titanium dioxide, iron oxide, copper oxide, zinc oxide, zirconium oxide, stannic oxide, and cerium oxide.  
   
   
       20 . The method of  claim 14  wherein said fine particles are iron oxide particles and said synthetic oil is polyol ester or polyalkylene glycol.  
   
   
       21 . The method of  claim 19  wherein said dispersant is anionic, non-ionic, or a combination thereof.  
   
   
       22 . The method of  claim 19  wherein said dispersant is selected from the group consisting of sulfosuccinates, alkoxylated polyaromatics, 12-hydroxystearic acid, polyhydroxystearic acid and combinations thereof.  
   
   
       23 . The method of  claim 14  wherein said particles are iron oxide particles having a median particles size of about 30 nanometers or less, and wherein said dispersant is at least one selected from the group consisting of sulfosuccinates, alkoxylated polyaromatics, 12-hydroxystearic acid, polyhydroxystearic acid and mixtures thereof.  
   
   
       24 . The method of  claim 14  wherein said dispersion composition comprises metal oxide particles having a median particle size of less than about 50 nanometers.  
   
   
       25 . The method of  claim 14 , said method further comprising combining said dispersion composition with a refrigerant composition.  
   
   
       26 . A method of using a refrigeration oil having fine particle dispersion, said method comprising providing said refrigeration oil to a mechanical system to transfer heat from a heat source to a heat sink.  
   
   
       27 . The method of  claim 26  wherein said mechanical system is selected from the group consisting of a refrigeration apparatus, heating apparatus and air conditioning apparatus.  
   
   
       28 . The method of  claim 27  wherein said mechanical system is a heat pump, refrigerator, air conditioner, or secondary loop system.  
   
   
       29 . The method of  claim 27  wherein said method further comprises combining said refrigeration oil having fine particle dispersion with a refrigerant composition.  
   
   
       30 . A method of using a heat transfer fluid dispersion composition comprising fine particles of metal or metal oxide dispersed in a heat transfer fluid selected from water, aliphatic alcohols, aliphatic glycols, silicones, hydrocarbons, fluorine-containing refrigerants, or non-fluorine containing refrigerants and at least one dispersant, said method comprising providing said heat transfer fluid dispersion composition to a mechanical system to transfer heat from a heat source to a heat sink.