纤维膜过滤特性的数值模拟

Filtration performance of fiber membranes by numerical simulating

一个高性能过滤膜除了与纤维自身结构参数有关联外,过滤时的操作条件对其也有重要影响。为研究纤维膜过滤效率、过滤压降与过滤速度、孔隙率以及过滤膜厚度之间的关系,以更好地对实际过滤进行优化,本研究从纤维膜的过滤机理进行出发,采用FLUENT多孔介质离散相模型对纤维过滤器的流场进行模拟。结果表明,膜前后压降会随着过滤速度和膜厚度的增大而增大;一定范围内纤维膜孔隙率适度增加,截留率变化不大,但是膜压差会逐渐减小;同时过滤速度对颗粒截留率有影响,速度增大时,粒子轨迹发生偏移,导致过滤膜一部分过早发生堵死,而一部分作用减弱,影响了过滤效果。

In addition to the structural parameters of filer membrane,the actual operational conditions of filtering also have an important impact on filtration efficiency. To study the relationship between the filtration efficiency,the pressure drop and the porosity,filtration velocity,and the thickness of membrane,then better optimizing the actual filtration efficiency,the porous media model of FLUENT-DPM was used to simulate the flow field based on the the mechanism of filtration. The results showed that the pressure drop would increase with the increment of filtration velocity and film thickness; rejection rate changed little when membrane porosity increased within a certain range,while the pressure drop decreased. Meanwhile,filtering velocity had an effect on particle rejection,the particle tracking would be skewed with increasing velocity. This could lead to part of the membrane blocked prematurely,which was not conducive to the improvement of filtration efficiency.