Vapor–liquid separation of mixtures R134a/R600a at horizontal branch T-junctions.

• Vapor-liquid separation of R134a/R600a at T-junctions was investigated experimentally. • Effects of inlet flow conditions were revealed. • Phase separations of mixtures and pure fluids were compared. • Effects of diameter ratio and branch angle were studied. As a promising separator, T-junction can be easily incorporated into the thermodynamic systems. Previous researches have investigated the phase separation of air-water and pure refrigerants but here the separation performance of mixtures at horizontal branch T-junctions is reported. Experiments were conducted to explore the effects of the flow conditions, the mass fractions and the geometric structures on the phase separation of R134a/R600a. During the experiments, the flow parameters including the inlet mass flux, the vapor quality and the mass flow ratio of the branch to the inlet, were varied. Three mixtures with R134a mass fraction 0.3030, 0.5202 and 0.7053 were employed. Furthermore, for the configurations of branching T-junction, the diameter ratio of the branch to the inlet was set to be 0.75 and 1.0, and three branch angles (45°, 90° and 135°) were considered. From the generated data, it was found that the branch outlet quality is always higher than the inlet quality, and the vapor fraction of branch outlet decreases with the increase of inlet vapor quality. The higher the mass flow ratio is, the larger the vapor fraction of R134a/R600a is. Under the experimental conditions, the mixtures with R134a mass fraction 0.3030 and 0.5202 have lower vapor fraction than R134a at inlet quality 0.1–0.5. As for the geometric effects, when the mass flow ratio is relatively large, more vapors usually prefer to flow into the branch with the smaller diameter, and vapor fraction for the angle 45° is lower than those for angles 90° and 135° [ABSTRACT FROM AUTHOR]