硅橡胶复合膜用于渗透蒸发的膜传质动力学(Ⅰ)膜面上的对流传质

MASS TRANSFER KINETICS OF PERVAPORATION BY USING COMPOSITE SILICONE RUBBER MEMBRANE (Ⅰ) CONVECTIVE TRANSPORT ON MEMBRANE SURFACE

利用自制的硅橡胶平板复合膜对低浓度乙醇水溶液进行渗透蒸发分离乙醇实验 ,研究了过程的传质动力学。基于液 -膜的串联传质阻力模型 ,通过实验测定了膜的总传质系数 ,采用对比差值方法将总传质系数拆分为膜面上的液膜传质系数和膜内的扩散传质系数两部分 ,分析了液相边界层阻力和膜扩散阻力对总传质系数的影响。特别针对膜面上液体流动状况对膜传质的影响进行了探讨 ,得出了液膜传质系数与Reynolds数及温度的关联式。

The pervaporation of ethanol from dilute aqueous solution through a novel plate composite silicone rubber membrane was investigated.Based upon the well-known resistance-in-series model,the overall mass transfer coefficient across membrane was measured and split into two parts of liquid film mass transfer coefficient and diffusive mass transfer coefficient in membrane,by conducting an ingenious calculation from the experimental data with different skin layer thickness of membranes. This allowed the relative contributions of the liquid film boundary layer resistance and the membrane resistance to be elucidated. Especially,the effects of liquid flow status on the surface of membrane on mass transfer of membrane was revealed,from which the correlations between liquid film mass transfer coefficient and Reynolds number as well as feed temperature could be obtained.