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纳滤膜的应用日益广泛,但其传质机理和优化设计的研究还有待深入.本文首先描述了表征高分子膜纳滤的道南-位阻孔模型(Donnan Steric Pore Model,DSPM),进而描述了在DSPM模型基础上发展起来的表征错流纳滤的孔-极化输运模型(Pores and Polarization Transport Model,PPTM).针对在PPTM模型中用经验模型描述膜上方溶液速度场的不足,用Navier-Stokes方程和连续性方程来描述溶液在膜上方自由空间内的流动,并用有限元方法模拟膜上方的溶液错流速度场,从而实现了膜内传质的DSPM模型、膜上方离子浓度场、膜上方自由空间流场的多场耦合有限元分析.通过与实验结果以及传统PPTM结果的对比可以发现,该修正方法能反映膜上方自由空间中的溶液速度场和离子浓度场的变化趋势并且在数值上也更为逼近实验值.改进后的模型将为高分子膜错流纳滤过程的优化设计提供更可靠的理论依据.
The application of nanofiltration membrane is more and more widely used, but the research on its mass transfer mechanism and optimization design still needs further study.In this paper, the Donnan Steric Pore Model (DSPM) The Pores and Polarization Transport Model (PPTM), which is developed on the basis of DSPM model, is described in this paper.According to the insufficiency of describing the solution velocity field above the membrane in the PPTM model, Navier-Stokes equation and continuity equation are used to describe the flow of the solution in the free space above the membrane. The velocity field of the solution above the membrane is simulated by the finite element method, so that the DSPM model of membrane mass transfer, the ion concentration above the membrane Field and free-space above the membrane by multi-field coupled finite element analysis.Compared with the experimental results and the traditional PPTM results, it can be found that this correction method can reflect the trend of solution velocity field and ion concentration field in the free space above the membrane And the numerical value is also closer to the experimental value.The improved model will provide a more reliable theoretical basis for the optimization design of polymer membrane cross-flow nanofiltration process.