Detailed two-phase numerical analysis of falling film absorption over a horizontal tube

Abstract

A comprehensive two-phase numerical model of falling film absorption from a pure vapour over an isothermal horizontal tube is presented. The detailed two-dimensional elliptic Navier–Stokes equations in each phase are solved together to study the laminar LiBr solution-vapour flow characteristics from above the tube to the falling film below the tube. The liquid-gas interface is captured precisely by implementing a dynamically moving non-orthogonal mesh and an adaptive-grid Eulerian method. The fundamental balances of mass, energy, and force are enforced at the interface to model the heat and mass interchange between the two phases. The accuracy of the numerical model results is validated through comparisons with relevant numerical and experimental results from the open literature. New numerical results are presented for a parametric study of the liquid film inlet Reynolds number, the film inlet temperature, the tube diameter, and the distance between the tubes on the absorption rate, temperature, and mass fraction distributions.