Miscibility analysis of polyol-ester based oil SW32 with R404A and low-GWP refrigerant R452A.

Refrigerant/lubricant miscibility plays an important role in the overall thermal performance and reliability of refrigeration and air-conditioning systems. R452A is considred a viable replacement of R404A refrigerant due to its comparible thermophysical properties and low global warming potential. In this paper, the miscibility of a polyol ester based oil SW32 is experimentally investigated with R404A and R452A by varying the oil mass fraction from 5% to 70% over the temperature range of 243.15K to 313.15K. The results revealed R452A is completely miscible with SW32 oil up to 30% oil mass fraction over the whole temperature range considered in the study followed by R404A which showed complete miscibility up to 20% oil mass fraction. Liquid phase separation showed the presence of three different types of immisicibility present for both refrigerant at higher oil mass fractions. Moreover, the low-global warming potential alternative, R452A demonstrated an 18% higher miscibility region with SW32 oil compared to R404A.