Parametric study of water vapor absorption into a constrained thin film of lithium bromide solution

This study presents a two-dimensional numerical simulation of a membrane-based absorber. A comprehensive parametric study is performed to quantify the influence of different operational and geometrical parameters such as solution film thickness, velocity, and concentration, cooling water temperature, and membrane thickness, pore size, and porosity on the absorption rate. In addition, the effect of membrane surface roughness on the absorption rate is investigated. The results indicate that the most critical parameters that affect the absorption rate are the solution film thickness and velocity. While it is impossible to control these parameters independently in a conventional absorber, they can be readily adjusted in the proposed membrane-based absorber to achieve the optimal performance. The simulation results suggest up to 3-fold enhancement in the absorption rate when a solution film thickness in the range of 50–100 μm is used.