Experimental Investigation of Thermophysical Properties of Lubricant Refrigerant Mixtures

Due to the F-Gas Regulation and the Kigali Amendment of the Montreal Protocol, high-global warming potential (GWP) refrigerants such as R134a are no longer considered viable, especially for small household appliances. Besides natural refrigerants and pure low-GWP refrigerants, refrigerant blends, which are often zeotropic, are growing in popularity as a solution to meet the combined requirements of a low environmental impact with thermodynamic efficiency. In many cases, the substitution of the refrigerant also requires a substitution of the compressor lubricant. Especially for refrigerant blends, the resulting thermophysical properties of the lubricant-refrigerant mixture are unknown and cannot easily be determined. This paper presents the experimental investigation of some important thermophysical properties for binary and ternary lubricant-refrigerant mixtures based on a POE ISO VG68 lubricant with the refrigerants R152a and carbon dioxide (R744) and their zeotropic blends.