Hamid Saffari*, Vahid Naziri
The Journal of Mechanical Science and Technology, vol. 24, no. 12, pp.2587-2596, 2010

Abstract : The heat transfer phenomenon occurring during stratified condensation inside an inclined tube is investigated theoretically and numerically. Differential equations governing the kinematic, dynamic, and thermal aspects for vapor condensation inside inclined tubes, which are derived from a thin film flow modeling, are solved simultaneously. These solutions are achieved by applying an explicit finite difference numerical method to predict the condensation heat transfer coefficient variations along the tangential and axial coordinates. The inclination angle is found to have a significant effect on condensation heat transfer coefficient inside inclined tubes. In addition, in accordance with the given physical and thermal condition of working fluids, there is a specific optimum inclination angle. In this study, the 30°–50° range from the horizontal position is found to be the range of the optimum inclination angle for achieving the maximum condensation heat transfer coefficient, with R134a, R141b, and R11 as the working fluids. The results of the present study are compared with experimental data, and a good agreement is observed between them.

Keyword : Filmwise condensation; Heat transfer coefficient; Optimum inclination angle; Stratified flow; Theoretical investigation