Refrigerant R22 is scheduled to be phased out and new and environmentally friendly refrigerants RE170 and RE170/R227ea have promising application. Miscibility of these refrigerants with lubricants has a large influence on working effect of the refrigerating system. For this reason

an experimental apparatus for testing miscibility of new refrigerants with lubricants was established based on standard SH/T 0699—2000. The miscibility values of promising refrigerants RE170 and mixed refrigerant RE170/R227ea with a mineral oil were studied. RE170 and the mineral oil were completely miscible at -50℃

as oil proportion changed from 10% to 60%. When R227ea mass fraction in mixed refrigerant RE170/R227ea changed from 35% to 60% and oil proportion was specified at 14.6%±0.5%

low phase separation temperature increased with increasing R227ea. When R227ea mass fraction was below 38%

the mixed refrigerant and mineral oil became miscible even at -50℃. When R227ea mass fraction was over 55%

the mixed refrigerant and mineral oil were immiscible even at room temperature. Finally

by combining the methods of empirical equation and solubility parameter

a new evaluation method was proposed to evaluate the miscibility of pure refrigerants and binary refrigerant mixtures with the mineral oil.