透析器中随机分布纤维管表面定浓度时传质模拟

通过数值模拟,研究了在透析器外壳内壁面的影响下,纤维表面定浓度时,中空纤维分布的随机性对透析器管外流场和浓度场的影响,同时考察了管外流体速度以及中空纤维填充密度对管外传质系数的影响.模拟结果表明:随机排布的方式对传质系数有较大的影响,但相比忽略壁面影响时的影响要小;Reynolds 数越大,传质系数也越大;在所研究的中空纤维填充密度范围内(10%～50%),随着填充密度的增大,透析器的管外传质系数先增大,后减小,变化幅度均较小,与忽略壁面影响的值比较发现,在填充密度小的时候壁面对传质有促进作用,填充密度大的时候则相反.

Numerical simulation of the shell-side mass transfer of randomly packed hollow fiber modules with constant fiber wall concentration

Mass transfer coefficient is an important parameter to evaluate the performance of hollow fiber modules. Numerical simulations were performed to study the wall effect of the module shell and packing pattern of hollow fibers which are randomly distributed, as well as the influences of flow Reynolds number to the mass transfer coefficient. The fiber wall concentration was assumed to be a constant value in this study. It was found that, the mass transfer coefficient increases with flow Reynolds number. Further study reveals that different packing patterns of hollow fibers result in different mass transfer coefficient values. This effect comes out more remarkable when neglecting the module wall effect. By varying the packing density from 10% to .50%, mass transfer coefficient increases first and then decreases experiencing a maximum value. Comparing to that with no wall effect, we found that, the wall effect promotes the mass transfer in a relatively low packing density but comes to the contrary as the packing density getting higher.