Abstract: Non-isothermal falling film flow is common in distillation process,which has great effect on the mass and heat transfer process on the surface of packing due to its particular property. In this paper,visualization device was set up and morphologic change of non-isothermal falling film flow on structured packing surface,in which liquid phase was heated by packing,was observed and analyzed through laser induced fluorescence system. Wetting area and film thickness were compared under different condition. Wetting area decreased remarkably with the increase of packing temperature,leading to dry plate phenomenon. The increase of local film thickness in wave trough of packing and formation of rivulet and irregular droplets were captured by LIF as well. Liquid aggregation and dispersion trajectories disappeared,weakening the redistribution and surface renewal ability. As a result,the shrinkage of non-isothermal falling film on structured packing surface is significant,which calls for enough attention to pay in industrial production for the weakening of heat and mass transfer capability.

Key words: non-isothermal falling film flow, LIF, film shrinkage, packing

摘要： 非等温降膜流动在精馏过程中较为常见，其流动特性较为特殊，对填料表面的质量和热量传递有重要影响。本文搭建了可视化的实验装置，在保证液相室温进料的前提下升高填料温度，在规整填料表面构造液相被加热的非等温降膜流动，运用激光诱导荧光技术对液膜形态变化进行观测分析，对液体润湿面积、液膜厚度等参数进行比较。结果表明，随着填料温度的升高，液体润湿面积显著减小，波谷处液膜厚度显著增加，液膜逐渐收缩为沟流，填料表面的不规则液滴数目增多，干板现象越发严重。液体的聚并和分散轨迹消失，液相再分布及表面更新能力降低。因此，填料表面的非等温降膜流动液膜收缩现象十分明显，降低传热传质能力，需在工业生产中引起足够重视。

关键词: 非等温降膜流动, 激光诱导荧光技术, 液膜收缩, 填料