Refrigeration oil and compositions with carbon dioxide refrigerant

摘要

Lubricant compositions comprising certain mixtures of esters of pentaerythritol, di-pentaerythritol, tri-pentaerythritol and higher pentaerythritol oligomers are ideally suited for use with CO2 as refrigerant in heat transfer devices provided that at least 30% by weight of the esters are esters of pentaerythritol oligomers containing 4 or more pentaerythritol monomer units and wherein a majority of the alkylcarboxylate groups are straight chain C3-6 alkanoyl groups, such as n-pentanoyl. Said mixture of alkylcarboxylate esters are shown to not only have higher than expected viscosity and exceptional CO2 miscibility, but also possess excellent lubricity, film building properties and load bearing properties even as part of a lubricant/CO2 solution.

主权项

1. A working fluid for a heat transfer device comprising
i) CO2 as a refrigerant, and ii) a polyol ester lubricant composition having a viscosity index of 130 or higher comprising a mixture of esters of formula I wherein n is an integer of from 1 to 20, each R is independently an alkyl carbonyl of from 5 to 10 carbon atoms, each R1 is independently selected and is either a group R or a substituent of formula II: and wherein from 70% to 100% of all R groups in the mixture of compounds of formula I are selected from isomers of alkyl carbonyl groups of 5 carbon atoms, at least 50% of all groups R in the compounds of formula I present in the working fluid are n-pentanoyl, and wherein the polyol ester lubricant composition ii) comprises: a) from 20 to 45 wt % compounds of formula I wherein n is 1 and each R1 is independently selected and is a group R, b) from 15 to 20 wt % compounds of formula I wherein n is 2 and each R1 is independently selected and is a group R, c) from 10 to 15 wt % compounds of formula I wherein n is 3 and each R1 is independently selected and is a group R, and d) from 30 to 55 wt % compounds of formula I which are pentaerythritol oligomers of 4 or more pentaerythritol monomer groups.