Abstract:

According to the theoretical model for laminar flow,the mass transfer in the shell-side of randomly distributed hollow fiber bundles under two boundary conditions is investigated.One boundary condition assigns a constant mass flow rate, and the other assigns a constant concentration.The correlations of mass transfer Sherwood number are obtained under different packing ratios.The results show that the mass transfer for the axial laminar flow in the randomly distributed fiber bundles can be divided into developing region and fully developed region as well as those in a tube.In the fully developed region of a given randomly distributed fiber bundle, Sherwood number is a certain value and much smaller than that in the fully developed region of a regular array fiber bundles.The non-uniform distribution of hollow fibers decreases the performance of mass transfer in the module.In the developing region of a given random distributed fiber bundle, Sherwood number is also smaller than that in the developing region of in the regular array fiber bundles.The packing ratio affects not only the coefficient B, but also the exponents a of Re and b of Sc in the correlation Sh=BRe^aSc^bf(d_e/L).

Key words:

随机分布, 中空纤维, 传质系数, 数值模拟

摘要：

按层流流动理论模型，对纤维为随机分布的中空纤维膜组件的壳程，在恒定壁面传质量和恒定壁面浓度边界条件下的传质现象进行了数值模拟，并得到了不同装填率下传质Sherwood数关联式。结果表明，纵向层流时，随机分布纤维间的传质仍可分进口段和充分发展段。对于某一给定的纤维束，在传质的充分发展段，传质Sherwood数为一个定值，且较纤维束规则排列时小得多，纤维分布不均一性将导致膜组件的传质能力下降。在传质进口段，传质Sherwood数也较纤维束规则排列时要小，装填率不但对传质系数的关联式Sh=BRe^aSc^bf(d_e/L) 的系数B值有影响，且对该式中的Reynolds数的指数a和Schmidt数的指数b值也均有影响。

关键词:

随机分布, 中空纤维, 传质系数, 数值模拟