中文摘要：

分子蒸馏是一种高效的液液分离技术，但由于缺乏对其流体力学性质的认识，使得该项技术还多停留在实验室阶段。本实验通过高速摄像法，以水和丙三醇溶液作为测试液体，在冷模常压下，对在不同操作工况下蒸发壁面上的液膜形态进行图像记录，来研究刮膜式分子蒸馏设备内的流体力学性质。实验发现在整个操作过程中壁面主要出现4种不同的液膜形态：点状分布、线状分布、部分成膜和整体成膜。根据实验数据作出的壁面液体流型图证实了液膜形态与过程的转速，进料速度及物料性质有关。除此之外利用量纲分析法对影响成膜的各因素进行分析，得到与成膜过程相关的三个无量纲数Π1、Π2和Π3。使用非线性最小二乘法对实验数据进行拟合，得到整体成膜状态下方程Π3=f（Π1，Π2）的具体形式，再利用丙三醇作为测试液体验证了方程Π3=f（Π1,Π2）的准确性。结果表明成膜临界速度ucr（Π3）作为判断壁面流型的标准是可行的，其大小与过程的雷诺数、韦伯数及设备的高径比有关。成膜临界速度ucr经验关联式的提出为分子蒸馏设备的理论研究和工业应用提供了参考。

英文摘要：

Molecular distillation is a highly efficient liquid-liquid separation technology. However, due to the inadequate knowledge of its hydrodynamic characteristics, this technology is still remained at the laboratory stage. By the help of the high speed photography and using the water and glycerol solution as tested fluids, respectively, the hydrodynamic characteristics of the fluid in the wiped film molecular distillatory （WFMD） was investigated by identifying the film pattern of the fluid on the evaporating wall of the WFMD under the condition of cold model and at normal pressure. The experimental results show that, depending on the rotor rotating speed, fluid feeding rate and the physical properties of the tested fluid, there are four different forms of film can be occurred on the evaporating wall of the WFMD; they are point shape, linear shape, partial film and intact film. The dimensional analysis was used to analyze the effects of the above operating factors on the filmformation process, and the dimensionless numberΠ1,Π2 and Π3 associated with the film-formation process were obtained. The relative formula Π3=f （Π1,Π2） was determined with the nonlinear least square method and the determined formula was verified by the experiments with glycerol as tested fluid. As a result, it is reasonable to use the critical velocity of film formation u＊cr （Π3） as the criteria for judging the formation of the intact film on the evaporating wall of the WFMD. Moreover, the formula reveals that the value of u＊cr is correlated with the Reynolds number Re, the Webber number We and the ratio of the height to the diameter of the evaporator. This research could be helpful for the theoretical study and industrial design of the WFMD.