气-液两相降膜流动及传质过程的CFD研究

利用VOF法建立了考虑表面张力动量源项、气液相间摩擦力动量源项以及相问传质源项的CFD计算模型，定量描述了气．液两相逆流降膜传质过程。根据CFD模型，计算了不同液相进口浓度和不同气相流量条件下，异丙醇稀溶液的解吸过程，模拟得到的液相出口浓度与实验数据吻合很好。相界面处的浓度分布表明。随自由表面波动，界面浓度会发生剧烈脉动。液相总传质系数增强因子R的实验值与CFD模拟均表明，即使在很小的传质推动力下R也大于1。由于CFD模型不考虑Rayleigh-Benard-Maragoni效应，则这种现象，可解释为界面波动对传质增强的结果。这也证明增强界面波动是一种强化传质分离过程的有效途径。

The CFD Simulation of Mass-Transfer Process in Falling Film with Countercurrent Two-Phase Flow

A CFD model using the volume of fluid (VOF) method was presented for predicting the mass-transfer process of the two-phase countercurrent falling film, in which the momentum source term including surface tension and interface shear stress and a mass-transfer source term were given. The model was applied to simulate the stripping process of 2-Propanol dilute solution. It is found that the simulated outlet liquid concentrations under different inlet liquid concentrations and various gas flow rates are in good agreement with the experimental data. The simulations also confirm that with free surface waving the interface concentration fluctuate violently. The enhancement factor R from experiment and CFD simulation are both larger than 1, even under the little mass-transfer impetus. Since the Rayleigh-B?nard-Maragoni effect was not considered in the CFD model, the conclusion can be regarded as that in the simulation, the results of the enhancement of the mass-transfer process is caused by fluctuating interfacial waves, which also proves that fluctuating the interfacial waves is an effective means to enhance the separation efficiency.