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