Patent ID: 8188323

Claim:
A composition for improving lubricant return in refrigeration and heat transfer apparatuses, comprising: a) a refrigerant or heat transfer fluid selected from the group consisting of HFC-32 and HFC-125; HFC-125 and HFC-134a; HFC-32, HFC-125, and HFC-134a; HFC-32, HFC-125, HFC-134a, and n-butane; HFC-32, HFC-125, HFC-134a, and 2-methylpropane; HFC-32, HFC-125, HFC-134a, n-butane and 2-methylbutane; HFC-32, HFC-125, HFC-134a, n-butane and n-pentane; HFC-32, HFC-125, HFC-134a, 2-methylpropane and 2-methylbutane; HFC-32, HFC-125, HFC-134a, 2-methylpropane and n-pentane; HFC-125, HFC-134a, and n-butane; HFC-125, HFC-134a, and 2-methylpropane; HFC-125, HFC-134a, n-butane and 2-methylbutane; HFC-125, HFC-134a, n-butane and n-pentane; HFC-125, HFC-134a, 2-methylpropane and 2-methylbutane; HFC-125, HFC-134a, 2-methylpropane and n-pentane; HFC-125, HFC-134a, HFC-227ea, n-butane and 2-methylbutane; HFC-125, HFC-134a, HFC-227ea, n-butane and n-pentane; HFC-125, HFC-134a, HFC-227ea, 2-methylpropane and 2-methylbutane; HFC-125, HFC-134a, HFC-227ea, 2-methylpropane and n-pentane; R401A; R401B; R402A; R402B; R403A; R403B; R410B; R413A; R414A; R414B; R416A; R419A; R422B; R422c; R422D; R423A; R407A; R407B; R407D; R407E; R408A; R424A; R425A; R426A; R427A; R428A; and R508B; and b) a lubricant and c) at least one perfluoropolyether (PFPE), wherein said lubricant is non-miscible in said refrigerant or heat transfer fluid, and (i) at least one of the end groups of said perfluoropolyether is a functionalized group selected from the group consisting of esters, hydroxyls, amines, amides, cyanos, carboxylic acids and sulfonic acids; or (ii) at least one of the two end groups of the perfluoropolyether is an unfunctionalized branched or straight chain perfluoroalkyl radical; and wherein the amount of said perfluoropolyether is less than 1% by weight relative to said refrigerant or heat transfer fluid.