An elliptic numerical analysis of water vapour absorption into a falling film in vertical parallel plate channels

Abstract

An implicitly coupled elliptic numerical model is applied to study the two-phase falling film absorption inside a parallel plate vertical channel. A complete set of two-phase two-dimensional governing equations are solved for co-current laminar flows of LiBr solution and water vapour. A precise liquid-gas interface is determined dynamically during solution over a non-orthogonal structured moving mesh. Fundamental interface boundary conditions are implemented to model the heat and mass interchange between the two phases. The capability of this new model is demonstrated through detailed comparisons with two previous parabolic and elliptic models. The impacts of the interface heat of absorption and mass fraction condition and the liquid film diffusion coefficient are investigated. New results are presented to examine the channel inlet pressure effect on the liquid film thickness development over the cold wall and the heat and mass transfer at the interface.