膜蒸馏跨膜传质过程的新模型——TPKPT

A New Method to Describe the Mass Transfer Process in Membrane Distillation-TPKPT Model

以纯水为介质，用直接接触式膜蒸馏测定了材料或性能参数不同的三种多孔疏水膜在不同温度下的渗透通量。根据测量结果计算出了各种膜在不同温度下的渗透系数，发现渗透系数均随着温度的升高而升高；这一结果说明Poiseuille流动在跨膜传质中起着非常重要的作用。据此提出了Knudsen扩散-Poiseuille流动两参数跨膜传质模型，即TPKPT模型。用此模型拟合实验数据，得到了三种实验用膜的模型参数。用这些模型参数计算膜在不同温度下的渗透系数，其值与实验测量值吻合较好，说明TPKPT模型能较好地描述膜蒸馏的跨膜传质过程。

To study the mass transfer process in membrane distillation, water fluxes of three kinds of membranes were measured at different temperatures by direct contact membrane distillation (DCMD), and the membrane distillation coefficients (C) for each membrane were obtained directly from experiment data. The fact that C increase with temperature indicates that Poiseuille flow plays a very important role in the process of mass transfer through the membrane. Based on this conclusion, a Two Parameters Knudsen- Poiseuille Transition (TPKPT) model, which emphasizes the effect of temperature on membrane distillation coefficient, was proposed to predicted the mass flux of membrane distillation. The parameters of TPKPT model for each membrane employed in this study were evaluated by a multi-component linear regression program. The values of membrane distillation coefficients for each membrane determined by TPKPT model agree well with the experimental data. The large contribution of Poiseuille flow to mass transfer may be attributed to the actually lager pore size and the increase of pore size with membrane temperature.