R12 has been the refrigerant of choice for, for example, auto air conditioning and domestic refrigerators, but has been found to have unacceptably high ozone depletion potential ("ODP") and global warming potential ("GWP").
Several replacements have been proposed for R12, but all have been found wanting. For example, 1,1,1,2-tetrafluoroethane ("R134a") is more acceptable environmentally, but cannot be used in most existing equipment owing to incompatibility with common refrigeration oils. Blends of R22 and R142b have better oil solubility, but in the event of a prolonged leak from the vapor phase can become flammable owing to fractionation causing a shift to over about 70% R142b. A blend of R22 and R124 has also been proposed (U.S. Pat. No. 4,303,536), but does not offer the solubility and cost-effectiveness of the subject ternary blend.
What is needed is a refrigerant blend which offers a combination of high energy efficiency (as indicated by a high "COP" or coefficient of performance), good oil solubility, and low cost, while remaining essentially nonflammable throughout a leak. Such blends would be useful as replacements for R12 in auto air conditioning, domestic refrigerators, commercial refrigeration units, and the like.