Numerical Analysis of Reflux Condensation

Download or read book Numerical Analysis of Reflux Condensation written by Foad Hassaninejadfarahani and published by . This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Reflux condensation occurs in a vertical tube when there is an upward core flow of vapour (or gas-vapour mixture) and a downward flow of the liquid film. The understanding of this condensation configuration is crucial in the design of reflux condensers and in loss-of-coolant safety analyses in nuclear power plant steam generators. A range of modelling approaches exists for co-current film condensation from gas-vapour mixtures in parallel-plate channels and tubes. These methods are based on marching from the inlet down the tube and do not apply to the reflux condensation. In this research, however, a two-dimensional two-phase model was developed that solves the steady, full elliptic governing equations in both the film and the gas-vapour core flow on a non-orthogonal mesh that dynamically adapts to the phase interface. Gas-vapour shear and heat and mass transfer at the interface were accounted for fundamentally. This modelling is a big step ahead of current capabilities by removing the limitations of previous reflux condensation models which inherently cannot account for the detailed local balances of shear, mass, and heat transfer at the phase interface. The model was developed and applied for co-current and counter-current flows in vertical parallel-plate channels, followed by vertical tubes. In each stage, the model results were compared against the available experimental and numerical data for validation purposes. A wide range of boundary conditions and geometries have been studied to examine the details of co-current and counter-current condensation phenomena. Velocity, temperature, pressure, and gas mass fraction profiles along with the axial variation of various parameters such as local Nusselt number, film thickness, interface and centre-line temperature and gas mass fraction are presented in parametric studies.