In accordance with the present invention refrigerant compositions are disclosed. The compositions comprise a refrigerant mixture consisting essentially of HFC-32, HFO-1234yf, and CO.sub.2. The compositions are useful as refrigerants in processes to produce cooling and heating, in methods for replacing refrigerant R-410A, and in refrigeration, air conditioning or heat pump systems. These inventive compositions match cooling capacity for R-410A within 10% with GWP less than 400 or less than 300.

The use of a refrigerant in organic Rankine cycle systems including at least one hydrofluoroolefin, having at least four carbon atoms represented by the formula (I) R1CHCHR2 in which R1 and R2 independently represent alkyl groups having from 1 to 6 carbon atoms, substituted with at least one fluorine atom, optionally with at least one chlorine atom.

In an aspect, the present invention provides a refrigerating machine oil comprising a poly(meth)acrylate as a base oil, wherein the poly(meth)acrylate comprises a hydrogenated poly(meth)acrylate, a content of a unit having a carbon-carbon double bond present at a terminal in the poly(meth)acrylate is 6% by mole or less relative to total units constituting the poly(meth)acrylate, and a kinematic viscosity at 40 C. of the hydrogenated poly(meth)acrylate is 1 to 1000 mm2/s, the refrigerating machine oil being used with a refrigerant comprising a refrigerant selected from difluoromethane, a mixture of difluoromethane and pentafluoroethane, a mixture of difluoromethane, pentafluoroethane, and 1,1,1,2-tetrafluoroethane, a mixture of pentafluoroethane, 1,1,1,2-tetrafluoroethane, and 1,1,1-trifluoroethane, an unsaturated hydrofluorocarbon, a hydrocarbon, and carbon dioxide.

The lubricating oil composition for a refrigerator of the present invention is used with a refrigerant containing carbon dioxide, and contains a base oil (A) containing a polyoxyalkylene glycol as a major component, and an alcohol (B) having at least one hydroxy group, in which a total number of the hydroxy group and an ether bond is from 2 to 3 (provided that the number of an ether bond may be 0).

A refrigeration oil composition includes: a mixture of a naphthenic mineral oil and at least one of a polyol ester oil and a polyvinyl ether oil; and at least one of a sorbitan compound and a glycerin fatty acid ester and a working fluid for a refrigeration system includes: the refrigeration oil composition; and one or more refrigerants selected from a hydrofluorocarbon refrigerant, a hydrofluoroolefin refrigerant and a carbon dioxide refrigerant.

The lubricating oil composition for a refrigerator according to the present invention is a lubricating oil composition for a refrigerator containing a base oil containing a low-viscosity base oil component having added thereto a polyoxyalkylene glycol compound having a kinetic viscosity at 100 C. that is higher than the low-viscosity base oil component, and the base oil has a kinetic viscosity at 100 C. of 2.4 to 25 mm.sup.2/s and a ratio (Mw/Mn) of a weight average molecular weight (Mw) and a number average molecular weight (Mn) of 1.3 to 13.

Provided herein are compositions comprising at least one estolide compound of formula:

##STR00001##

in which n is an integer equal to or greater than 0; m is an integer equal to or greater than 1; R.sub.1, independently for each occurrence, is selected from optionally substituted alkyl that is saturated or unsaturated, and branched or unbranched; R.sub.2 is selected from hydrogen and optionally substituted alkyl that is saturated or unsaturated, and branched or unbranched; and R.sub.3 and R.sub.4, independently for each occurrence, are selected from optionally substituted alkyl that is saturated or unsaturated, and branched or unbranched. Also provided are uses of the compositions described herein.

The present invention relates to a refrigerator oil containing a specified amount of a polyvinyl ether-based compound (A) containing a structural unit (a1) having a methoxy group in a side chain thereof and a specified amount of a polyvinyl ether-based compound (B) containing a structural unit (b2) of a specified structure; a refrigerator oil composition containing the refrigerator oil; and a production method the refrigerator oil.

The working fluid composition for a refrigerating machine of the present invention comprises a refrigerant comprising a first refrigerant component and a second refrigerant component, and having a global warming potential (GWP) of 500 or less, wherein the first refrigerant component is at least one selected from difluoromethane and tetrafluoropropene, and the second refrigerant component is at least one selected from carbon dioxide and a hydrocarbon having 3 to 4 carbon atoms; and a refrigerating machine oil comprising at least one selected from a polyol ester, a polyvinyl ether and a polyalkylene glycol compound as a base oil, wherein a carbon/oxygen molar ratio of the base oil is 2.5 or more and 5.8 or less.

The present invention provides a refrigerating machine oil comprising, as a base oil, a polymer having a structural unit represented by the following formula (1): ##STR00001##
wherein R.sup.1, R.sup.2 and R.sup.3, which may be the same as or different from each other, represent a hydrogen atom or a hydrocarbon group; and R.sup.4 represents a hydrocarbon group or an organic group containing an oxygen atom, and having a number average molecular weight Mn of 300 or more and 3000 or less and a ratio of a weight-average molecular weight Mw to a number average molecular weight Mn (Mw/Mn) of 1.10 or more and 2.00 or less, and the refrigerating machine oil being used with a refrigerant selected from the group consisting of difluoromethane, a mixture of difluoromethane and pentafluoroethane, a mixture of difluoromethane, pentafluoroethane and 1,1,1,2-tetrafluoroethane, a mixture of pentafluoroethane, 1,1,1,2-tetrafluoroethane and 1,1,1-trifluoroethane, unsaturated hydrofluorocarbons, hydrocarbons and carbon dioxide.