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利用有限元分析软件Comsol Multiphsics中的自由流动、达西定律以及物质传递耦合膜阻力公式,建立中空纤维膜的膜污染计算流体力学(CFD)模型,并通过实验室小试对模型参数进行了修正。结果表明,过滤初期,膜通量的快速下降是由于污染物质吸附作用在膜表面快速累积而引起的,随后,由于污染物质吸附达到动态饱和,同时滤饼层尚未形成,总阻力系数增长缓慢,因而通量下降亦较缓慢;最后,随着过滤的进行,已累积的污染物质在膜表面分布趋于均匀,滤饼层基本形成,此阶段通量下降较为明显。模型可准确地预测中空纤维超滤膜膜通量的变化,解析膜内污染物质浓度分布及其浓差极化层厚度动态变化,为研究膜内物质浓度分布可视化提供手段。
The computational fluid dynamics (CFD) model for membrane fouling of hollow fiber membranes was established by using the free flow, Darcy’s law and the resistance formula of mass transfer coupling membrane in Comsol Multiphsics, and the parameters of the model were corrected by lab test . The results showed that the rapid decrease of membrane flux was mainly caused by the rapid accumulation of pollutants on the surface of the membrane during the initial stage of filtration. Subsequently, the saturated resistivity of the membrane was not yet formed due to the adsorption of pollutants, and the total drag coefficient increased slowly. The flux decreased slowly. Finally, as the filtration progressed, the accumulated pollutants tended to be uniform on the surface of the membrane and the cake layer was basically formed. The flux decreased more obviously at this stage. The model can predict the change of membrane flux of hollow fiber ultrafiltration membrane accurately, analyze the concentration distribution of pollutants in the membrane and the dynamic change of the thickness of the concentration polarization layer, and provide a means to study the visualization of the membrane material concentration distribution.