Development of Miscibility Improved Oil for R32

Abstract

R32 is a refrigerant that excels in various applications and has seen wide use in recent years. However, R32 is known to have lower miscibility with refrigeration oils than do other refrigerants such as HFCs and HFOs. Moreover, when R32 is dissolved in refrigeration oils, the kinematic viscosity of the oil drops sharply. This has made it difficult to develop oils with improved miscibility with R32 that do not suffer from these drops in kinematic viscosity. Our work has shown that the addition of a new base material to POE improves miscibility with R32 while reducing the drop in kinematic viscosity that occurs when R32 is dissolved in it. Using this technology, we have developed new refrigeration oils whose critical solution temperatures were −20°C or below under R32 atmosphere. The kinematic viscosities of the new oils when R32 is dissolved in them were equal to or greater than those of POE oils currently used for R410A. In addition, the new oils have not only expanded the range of choices for POEs for R32, but also shown the possibilities for use with HFOs. In this study, we report our test methods and various characteristics of the oils under R32 and HFOs.