Oil retention and pressure drop of R1234yf and R134a with POE ISO 32 in suction lines

A quantitative comparison of oil retention and pressure drop characteristics of refrigerants, R1234yf and R134a with POE32 oil in 10.2 mm inside diameter horizontal and vertical suction lines at a saturation temperature of 13°C with 15°C of superheat is presented. High speed videos of the flow were taken to identify the flow regimes as the mass flux was varied. Test results show that for the same system cooling capacity R1234yf and R134a have very similar oil retention; however, the use of R1234yf results in 20% to 30% higher pressure drop. It was also found that inclined suction lines retain more oil than vertical suction lines.