Influence of Saturation Temperature on Pressure Drop during Condensation of R-134a inside a Dimpled Tube: A Numerical Study

In this study, the numerical simulations for multiphase fluid flow inside a smooth and dimpled tube were investigated at low mass velocities during the condensation of R-134a to determine the pressure drop. The numerical analysis was conducted at a dryness fraction of 0.5, temperature of saturation of 30–50°C, and mass fluxes range between 50 and 200 kg m −2 s −1 . The impact of mass flux on the pressure drops had been studied along the smooth and dimpled tube. The smooth and dimpled tubes were designed with an inside and outside diameter of 8.38 and 9.54 mm, respectively. The specifications of the dimpled tube were o = 1 mm, p = 5.08 mm, z = 4.99 mm, and e = 0.5 mm. The Volume of Fluid (VOF) flow model was utilized in this study and the flow field was assumed to be three-dimensional, transient and turbulent. With an increase in mass flux for both smooth and dimple tubes, total pressure drop and frictional pressure drop increases. The numerically simulated two-phase friction factor was compared with the well-known correlations of the dimple tube. Also, the numerically simulated pressure drop for the dimple tube was more compared with the plain tube and the pressure drop decreases with an increase in temperature of saturation.