波纹板填料表面液体降膜流动的特性分析

Analysis of characteristics of liquid falling film flow on corrugated sheet packing

基于降膜流动实验台,结合计算流体力学方法(Computational Fluid Dynamics, CFD)研究了波纹板表面液体的平均液膜厚度和有效润湿面积等定量信息,并通过三维模拟进一步分析了喷淋密度和波纹倾斜角度β对降膜流动特性的影响。结果表明,液体在波纹板表面的流动并非均匀,分为沟流和溪流两种形式;当喷淋密度较小时,液体在波谷内形成沟流,当喷淋密度达到400 m^(3)/(m^(2)·h),液体跨越相邻波纹进行溪流流动;两种形式波纹板整体的润湿性能均较差,且液膜厚度分布不均;波纹倾斜角度对降膜流动特性影响较大,90°时更有利于提高有效润湿面积。

The falling film flow characteristics of the liquid in corrugated sheet packing are the key factors affecting its mass transfer performance. In this work, a falling film flow experimental bench was built and combined with computational fluid dynamics to study the falling film flow of the corrugated sheet, the influence of spray density and corrugation tilt angle on flow characteristics was analyzed,and quantitative information of average liquid film thickness and the effective wetting area was obtained through three-dimensional simulation. The results showed that the three-dimensional CFD model can accurately predict the liquid falling film flow behavior and calculate the characteristic parameters. The flow of liquid on the corrugated sheet was not homogeneous but was classified as two kinds of forms: groove flow and rivulet flow. As the spray density was low, the liquid flow formed a groove flow in the trough while it changed as rivulet flow along the adjacent ripples when the spray density reached 400 m^(3)/(m^(2)·h), compared with channel flow, the rivulet form was more beneficial to increase the contact area of gas and liquid. However, no matter which flowed mode, the overall wettability of the corrugated sheet was poor, and the thickness distribution of the liquid film was not uniform, which was not conducive to mass transfer. The tilt angle of the corrugation had a greater influence on the flow characteristics of the falling film, after extensive research on the tilt angle, it was found that when the tilt angle was 90°, it was more conducive to increasing the effective wetting area and reducing the average liquid film thickness. The results of this study have theoretical guiding significance for controlling the liquid film thickness and increasing the effective wetting area during the falling film flow, and also have application value for improving the corrugated sheet structure and increasing the mass transfer efficiency.