Effect of saturation temperature on the condensation of R134a inside an inclined smooth tube

Abstract

In this study, numerical simulations of the condensation of R134a inside an inclined smooth tube are conducted. The effects of different parameters such as saturation temperature, tube inclination angle, vapour quality, and mass flux, on variations of the condensation heat transfer coefficient and pressure drop along the tube were investigated. The simulations were performed at a uniform heat flux of 5050 W/m2, mass fluxes of 100–400 kg/m2s, saturation temperatures of 30–50 °C, vapour qualities of 0.1–0.9, and inclination angles of −90 to + 90° It was assumed that the flow field was three-dimensional, transient, and turbulent. The volume of fluid model was used to solve the governing equations. The simulated results for the condensation heat transfer coefficient and pressure drop showed good correlation with the available experimental data. The results also demonstrated that the condensation heat transfer coefficient and pressure drop along the tube increased with decreasing saturation temperature, and increasing mass flux and vapour qualities. It was also determined that there was an optimum inclination-angle-range, −30 to −15°, in which the condensation heat transfer coefficient attained a maximum value.