Oil Additives for "Drop-In" Replacement Refrigerants

Hydrofluorocarbon (HFC) refrigerants are the leading candidate replacement refrigerants for refrigerant R-502. HFC refrigerants have no ozone depleting potential and very low global warming effect. Their thermodynamic properties and performance closely match that of R-502 so that little or no change is needed in refrigeration system components to utilize HFC refrigerants. HFC refrigerants are not "drop-in" replacements for R-502 because HFC's are not miscible with existing compressor lubricants. The compressor oil must be changed to a synthetic polyolester (POE) oil to prevent fouling of heat exhangers. This oil change is a costly process which makes conversion of existing refrigeration system uneconomical. The purpose of this proposed project is to correct this problem through the use of additives to improve the miscibility of HFC's with existing compressor oil. Through Solubility Parameter Theory we have identified a number of candidate substances that would serve this purpose. The proposed program will investigate these candidates through standard solubility testing methods.