A two-phase flow CFD model using the volume of fluid (VOF) method is presented for predicting the hydrodynamics of falling film flow on inclined plates, corresponding to the surface texture of structured packing. Using the proposed CFD model the influence of the solid surface microstructure, liquid properties and gas flow rate on the flow behavior was investigated. From the simulated results it was shown that under the condition of no gas flow the liquid flow patterns are dependent on the microstructure of the plates, and proper microstructuring of the solid surface will improve the formation of a continuous liquid film. It was also found that liquid properties, especially surface tension, play an important role in determining the thinfilm pattern. However, there are very different liquid film patterns under the action of gas flow. Thinner liquid films break easily, but thicker liquid films can remain continuous even at higher gas flow rates, which demonstrates that all factors affecting the liquid film thickness will affect the liquid film patterns under conditions of counter-current two-phase flow.

Structured packings are widely used in many separation processes. In this paper, the liquid film flow behavior as well as mass transfer efficiency on the novel and the traditional structured packings is investigated after being simplified into multibaffled and inclined plate, respectively. The novel structured packing has a number of openings punched through the ridges on the inner and outer sides of the packing surface, and this structure corresponds to a certain flow pattern that influences mass transfer processes other than the traditional ones. The CFD method and VOF model are applied to investigate the vapor−liquid two-phase flow behavior and mass transfer process. Isopropanol desorption on the two kinds of plates is studied experimentally and numerically, and the experimental and simulation results are in good agreement. A significantly higher mass transfer efficiency of the multibaffled plate is observed, and the simulation results indicate successfully that the higher mass transfer efficiency on the novel structured packing results from the increased renewal rate and disturbance of liquid film flow.

Falling liquid film flow is a sort of ubiquitous transport phenomenon occurring in chemical engineering. Fundamental research on the flow and mass transfer behavior of falling liquid film flow on plates with different structures can help engineers to develop more efficient equipment. In this paper, falling liquid film flow on a plate with rectangular holes is investigated with both numerical and experimental methods. Mass transfer experiments show that opening rectangle-shaped narrow holes on a plate can enhance the mass transfer efficiency. Compared to an ordinary plate, the vapor-liquid mass transfer rate on a holed plate can be increased by 10-20%. To analyze the detailed flow and mass transfer behavior, the computational fluid dynamics model (CFD) based on the volume of fluid (VOF) method is developed. In this model, the Marangoni effect induced by mass transfer is considered. The new model was demonstrated to give more satisfactory results than the previous model.