Experimental and CFD studies on the effects of surface texture on liquid thickness, wetted area and mass transfer in wave-like structured packings

Abstract

A novel wave-like polyline-arc (WPA) structured packing is proposed to improve hydrodynamic performance and mass transfer. The experimental results show that the WPA packing yields a lower pressure drop, a higher capacity and a higher mass transfer efficiency compared with the traditional Mellapak 125.X packing. A multi-scale CFD (Computational Fluid Dynamics) model is used to analyse the hydrodynamic performance, and a user-defined function (UDF) is added to the Fluent solver to evaluate the mass transfer efficiency. In the hydrodynamic simulation, we use unsteady 2D and 3D VOF models to explore the effects of surface texture on the liquid thickness and effective wetted area. The CFD results show that a rough surface has a positive effect on both the average film thickness and the wetted area, and the effect on the average film thickness is greater. The mass transfer results indicate that a rough surface enhances the local gas–liquid contact efficiency by disturbing the fluid flow and prolongs the liquid–gas contact time. The simulation results show that the surface texture has a smaller effect on the wet pressure drop than on the mass transfer efficiency and are in agreement with the experimental data.