Lubricant refrigerant composition for hydrofluorocarbon (HFC) refrigerants

A method of separating a lubricant-refrigerant composition and returning a lubricant rich phase of the lubricant from a refrigerant rich phase of the refrigerant to a compressor, which comprises;

• permitting a liquid phase separation between the lubricant rich phase and the refrigerant rich phase wherein at a temperature of above −60° C. the lubricant rich phase resides below the refrigerant rich phase;
• removing the lower layer lubricant rich phase away from the upper layer refrigerant rich phase, and
• returning the lubricant rich phase to the compressor;
• wherein the refrigerant and lubricant comprise
• (A) at least one fluorine-containing hydrocarbon refrigerant containing 1 to 3 carbon atoms, further where fluorine is the only halogen in said fluorine-containing hydrocarbon with the proviso that 1,1,1,2-tetrafluoroethane is not the sole refrigerant;
• and
• (B) at least one lubricant comprising
• (1) a hydrocarbyl substituted arene,
• (2) a phosphate ester,
• (3) an organic ester of a carboxylic acid and an alcohol,
• (4) a perfluoropolyethylene,
• (5) an ether of the structure
• wherein R3 is hydrogen, a hydrocarbon group containing from 1 to 20 carbon atoms, or an alkyl substituted aromatic wherein the alkyl group contains from 1 to 12 carbon atoms, R4 is independently hydrogen, methyl or ethyl, R5 is acyl group containing from 2 to 20 carbon atoms, b is an integer of from 1 to 10 and a is an integer such that the product of a and b is at least two;
• (6) a polyether wherein the polyether is prepared by polymerizing an ether of the structure
• CH2═CHR1O—R2
• wherein R1 is hydrogen or an alkyl group containing from 1 to 4 carbon atoms and R2 is an aliphatic group containing from 1 to 8 carbon atoms,
• (7) a polyalphaolefin;
• or
• (8) a mineral oil.

A compression refrigeration system, comprising;

• a compressor, a condenser, an oil return valve, an oil return line, an expansion valve and an evaporator wherein the system is charged with a composition comprising
• (A) at least one fluorine-containing hydrocarbon refrigerant containing 1 to 3 carbon atoms, further wherein fluorine is the only halogen in said fluorine-containing hydrocarbon with the proviso that 1,1,1,2-tetrafluoroethane is not the sole refrigerant;
• and
• (B) at least one lubricant comprising
• (1) a hydrocarbyl substituted arene,
• (2) a phosphate ester,
• (3) an organic ester of a carboxylic acid and an alcohol,
• (4) a perfluoropolyethylene,
• (5) an ether of the structure
• wherein R3 is hydrogen, a hydrocarbon group containing from 1 to 20 carbon atoms, or an alkyl substituted aromatic wherein the alkyl group contains from 1 to 12 carbon atoms, R4 is independently hydrogen, methyl or ethyl, R5 is hydrogen or a hydrocarbon group containing from 1 to 20 carbon atoms or an acyl group containing from 2 to 20 carbon atoms, b is an integer of from 1 to 10 and a is an integer such that the product of a and b is at least two;
• (6) a polyether wherein the polyether is prepared by polymerizing an ether of the structure
• CH2═CHR1O—R2
• wherein R1 is hydrogen or an alkyl group containing from 1 to 4 carbon atoms and R2 is an aliphatic group containing from 1 to 8 carbon atoms,
• (7) a polyalphaolefin;
• or
• (8) a mineral oil;
• wherein at a temperature of above −60° C. a phase separation occurs such that at least two phases are formed, said phases being a refrigerant rich phase and a lubricant rich phase, further wherein the lubricant rich phase resides below the refrigerant rich phase, such that the lubricant rich phase is separated from the refrigerant rich phase by the oil return valve and the lubricant rich phase returned to the compressor by the oil return line.