Modeling of R-113 Saturate Vapor Condensation in a Vertical Pipe Using the VOF Method in a Three-Dimensional Formulation

Advances in computer technology have significantly expanded the possibilities for studying heat and mass transfer processes using Computational Fluid Dynamics (CFD) methods and, in particular, vapor condensation in pipes. One of the promising methods of numerical research is Volume of Fluid (VOF), which allows direct modeling of the behavior of the interphase surface in complex unsteady flows with mass transfer. Currently, the main efforts of researchers are aimed at the active development and testing of effective VOF models and algorithms and the selection of optimal characteristics of the grids used that are necessary for modeling a moving interphase surface and modes in which the vapor flow can be turbulent and the flow in the condensate film can consistently change from laminar (laminar-wave) to turbulent. An important issue remains the influence of taking into account real three-dimensionality in problems traditionally considered as two-dimensional: condensation of vapor on the surface of a horizontal cylinder, bundles of horizontal tubes, or in a vertical cooled tube. For this purpose, the authors previously performed methodological calculations, including verification of models and VOF algorithms as applied to condensation processes in pipes. Based on the results obtained in a two-dimensional (2D) formulation when modeling condensation in a vertical pipe of turbulent vapor flow, the optimal sizes of grid cells in the liquid film and vapor in the radial and longitudinal directions were selected, various turbulence models were tested, and the method for determining the constant in the Lee model was verified. When comparing the calculated values and data obtained experimentally at the Department of Engineering Thermal Physics of the National Research University MPEI, their good agreement was observed (arithmetic mean deviation 14.4%). This paper examines the results of modeling the specified problem in a three-dimensional (3D) formulation. Based on the performed calculations, the operability of the proposed algorithms, methods, and grid parameters was confirmed when transferring them from a two-dimensional to a three-dimensional problem statement. The values obtained from 3D modeling are in better agreement with the experimental data (average arithmetic deviation 10.2%); the accuracy of calculations relating to the laminar-wave mode of condensate film movement is significantly increased.