Numerical investigation of condensation inside an inclined smooth tube

Abstract

In this paper the effect of inclination angle on the condensation heat transfer coefficient, pressure drop and flow regime inside a smooth tube was investigated numerically. The working fluid was R134a at a saturation temperature of 40°C. The Volume of Fluid (VOF) multiphase flow formulation was utilized to solve the governing equations. Simulations were conducted at a heat flux of 5 kW/m2, at mass fluxes of 100 – 600 kg/m2.s, and the inclination angles were varied from vertical downward to vertical upward. The simulation results were successfully validated with the experimental data. The results showed that an optimum downward inclination angle of between -30° and -15° exists, for the heat transfer coefficients. It was also found that the effect of inclination angle on the pressure drop and void fraction became negligible at high mass fluxes and vapour qualities.