Lubrication for refrigerant heat transfer fluids
AssigneeHenkel Corporation
InventorsEugene R. Zehler, Nicholas E. Schnur
Life of this patent
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Abstract
Esters and mixtures of esters of polyhydric alcohols, e.g., of pentaerythritol, in which at least 22 number percent of the acyl groups in the esters are either branched or contain no more than six carbon atoms, are effective lubricants and/or lubricant base stocks for chlorine-free fluorocarbon refrigerant heat transfer fluids, particularly for chlorine-free heat transfer fluids such as Refrigerant 134a (1,1,1,2-tetrafluoroethane).
Claims20
A refrigerant working fluid comprising:
- (A) a fluoro-group-containing heat transfer fluid;
- and
- (B) a lubricant composition consisting essentially of materials selected from the group consisting of esters of (i) alcohols containing at least two --OH groups and (ii) organic carboxylic acids, wherein:
- (a) at least about 22 number percent of the acyl groups in the total of all the esters in said lubricant composition include no more than six carbon atoms, or include at least one carbon atom bonded to at least three other carbon atoms by single bonds, or both;
- (b) the ratio of the number percent of acyl groups in the total of all the esters in said lubricant composition that are that contain 8 or more carbon atoms and are unbranched to the number percent of acyl groups in the total of all the esters in said lubricant composition that are both branched and contain not more than 6 carbon atoms is not greater than about 1.56;
- (c) the number percent of acyl groups in the total of all the esters in said lubricant composition that contain nine or more carbon atoms is not greater than about 81;
- and
- (d) at least 62 number percent of the total of all the alcohol moieties in the esters in said lubricant composition contain at least one carbon atom that is bonded by carbon-carbon single bonds to four other carbon atoms.
A process for operating a mechanical refrigerating system comprising cyclic compression, liquefaction, expansion, and evaporation of a fluoro-group-containing heat transfer fluid, wherein the improvement comprises lubricating a part of the refrigerating system that comes into contact with the heat transfer fluid with a lubricant composition consisting essentially of materials selected from the group consisting of esters of (i) alcohols containing at least two --OH groups and (ii) organic carboxylic acids, wherein:
- (A) at least about 22 number percent of the acyl groups in the total of all the esters in said lubricant composition include no more than six carbon atoms, or include at least one carbon atom bonded to at least three other carbon atoms by single bonds, or both;
- (B) the ratio of the number percent of acyl groups in the total of all the esters in said lubricant composition that contain 8 or more carbon atoms and are unbranched to the number percent of acyl groups in the total of all the esters in said lubricant composition that are both branched and contain not more than six carbon is not greater than about 1.56;
- (C) the number percent of acyl groups in the total of all the esters in said lubricant composition that contain nine or more carbon atoms is not greater than about 81;
- and at least 62 number percent of the total of all the alcohol moieties in the esters in said lubricant composition contain at least one carbon atom that is bonded by carbon-carbon single bonds to four carbon atoms.
Dependencies are inferred from the claim text.