Near-azeotropic ternary compositions constituted by hydrogenated fluorocarbons and hydrocarbons, suitable as refrigerating fluids

Abstract

Near-azeotropic ternary compositions of hydrofluorocarbons with n-butane or isobutane selected from: A) 1,1,1,2-tetrafluoroethane (R134a) 65-94% by weight pentafluoroethane (R125) 2-25% by weight n-butane (R600) and/or isobutane (R-600a) 1-10% by weight B) 1,1,1,2-tetrafluoroethane (R134a) 65-94% by weight 1,1,1,2,3,3,3-heptafluoropropane (R227ea) 5-25% by weight n-butane (R600) and/or isobutane (R-600a) 1-10% by weight Said compositions have zero ODP, very low GWP and good solvent power for mineral lubricants. They are utilizable as drop-in substituents of R-12 in domestic refrigeration.

1. Drop-in substitutes for R 12 consisting of ternary near-azeotropic compositions: 
       
         
           
                 
                 
                 
               
                     
                 
                   1,1,1,2-tetrafluoroethane (R 134a) 
                   75-86% 
                   by weight 
                 
                   pentafluoroethane (R125) 
                   4-20%  
                   by weight 
                 
                   n-butane (R 600) 
                   2-4% 
                   by weight 
                 
                   or 
                     
                     
                 
                   1,1,1,2-tetrafluoroethane (R 134a) 
                   75-93% 
                   by weight 
                 
                   1,1,1,2,3,3,3-heptafluoropropane (R 227ea) 
                   5-20% 
                   by weight 
                 
                   n-butane and/or isobutane (R 600 & R 600a) 
                   2-4% 
                   by weight 
                 
                     
                 
             
                
               
               
                
                
                
                
                
                
                
                
               
            
           
         
       
       said compositions having the feature that the percent variation of the vapor pressure after 50% percent evaporation of the liquid at a temperature of 25° C. is comprised between 0.5 and 7% of the vapor pressure before said evaporation. 
     
     
       2. A method of refrigeration comprising condensing and evaporating the compositions of  claim 1 . 
     
     
       3. The drop-in substitutes as claimed in claim 1 wherein the drop-in substitutes consists of the following ternary near-azeotropic composition:
 1,1,1,2-tetrafluoroethane (R 134a),   pentafluoroethane (R 125) and   n-butane (R 600).   
     
     
       4. The drop-in substitutes as claimed in claim 1 wherein the drop-in substitutes consists of the following ternary near-azeotropic composition:
 1,1,1,2-tetrafluoroethane (R 134a),   1,1,1,2,3,3,3-heptafluoropropane (R 227ea) and   n-butane and/or isobutane (R 600 & R 600a).   
     
     
       5. A method of refrigeration which comprises evaporating and condensing a refrigerant mixture which can be obtained by adding HFC-125 to a mixture of HFC-134a and n-butane, wherein the presence of HFC-125 causes the flammability characteristics of the refrigerant mixture to be improved as compared to the flammability of the mixture of HFC-134a and n-butane. 
     
     
       6. The method of claim 5, wherein the n-butane content of the refrigerant mixture is from 2 to 4 wt. %. 
     
     
       7. A method for maintaining lubrication of mechanical parts of a compressor included in a refrigeration circuit, which comprises using a compatibilized lubricant-refrigerant mixture formed by combining a lubricant with a refrigerant mixture in accordance with claim 5. 
     
     
       8. The method according to claim 7, wherein the lubricant is mineral oil. 
     
     
       9. The method of claim 5, wherein the n-butane content of the refrigerant mixture is from 2 to 4 wt. %.