丝网板液膜流动及传质

doi:10.11949/j.issn.0438-1157.20141454

摘要/Abstract

摘要：

采用液膜流动测定及CO₂吸收实验较为系统地考察了固体壁面与丝网壁面液膜流动差异, 以及网孔尺寸对降膜流动及传质影响, 结果表明:在较低Re下, 丝网结构对液膜波动存在一定抑制作用。两种结构的壁面液膜波动振幅整体上随Re及距进口位置的增加而有所增加, 相比于固体壁面, 丝网壁面在沿流动方向不同位置处平均膜厚及波动振幅差异更小, 且在较低Re(<80)下, 液膜波动对液量更为敏感。不同孔径丝网板液膜流动观测结果表明, 液膜瞬时波动振幅及波动频率随丝网孔径的增加均出现了先增加后减小的变化趋势;在不同物系下, 当网孔尺寸≤2 mm时, 膜厚随网孔尺寸的增加逐步增大, 后随着网孔尺寸的进一步增大, 膜厚逐步减小。此外, CO₂吸收实验结果显示, 随着丝网孔径的减小, 测试板传质性能提升明显, 但单位面积网丝对传质贡献减少。

关键词: 流动, 传质, 液膜, 丝网板

Abstract:

The influence of substance structures as well as the mesh size of gauze on the flow dynamics and mass transfer behaviour of falling liquid film, has been studied experimentally. One smooth plate and six gauze plates with mesh size in the range of 0.3—13.0 mm were chosen as test plates. The results show that the film wave amplitude increases in the flow direction for both types of structures, and the gauze structure has an obvious suppressive effect on the film wave behaviour at low Reynolds number (Re). The variations of average film thickness and wave amplitude along the flow direction for the gauze plates are less noticeable in comparison with those over a smooth one, and the film wave behaviour for the gauze substance is much more sensitive to the liquid flow rate when Re<80. In addition, it is found that the average film thickness, film wave amplitude and fluctuation frequency for the gauze plates follow similar trend with mesh size goes up from 0.3 to 13.0 mm: the values initially increase to a peak value, then decrease obviously. Furthermore, the results from CO₂absorption into NaOH solutions reveal that when increasing the mesh size, the corresponding liquid side mass transfer coefficient decreases rapidly, but the contribution of unit wires to mass transfer rate increases remarkably.

Key words: flow, mass transfer, liquid film, gauze plates

中图分类号:

TQ021.1

胡剑光, 刘佳特, 王成, 于建国, 戴干策. 丝网板液膜流动及传质[J]. 化工学报, 2015, 66(S1): 71-80.

HU Jianguang, LIU Jiate, WANG Cheng, YU Jianguo, DAI Gance. Flow dynamics and mass transfer characteristics of vertically falling liquid film flow on gauze plates[J]. CIESC Journal, 2015, 66(S1): 71-80.

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