Abstract: This paper reports experimental and computational fluid dynamics (CFD) studies on the performance of microfiltration enhanced by a helical screw insert. The experimental results show that the use of turbulence pro-moter can improve the permeate flux of membrane in the crossflow microfiltration of calcium carbonate suspension, and flux improvement efficiency is strongly influenced by operation conditions. The energy consumption analysis indicates that the enhanced membrane system is more energy saving at higher feed concentrations. To explore the intrinsic mechanism of flux enhancement by a helical screw insert, three-dimensional CFD simulation of fluid flow was implemented. It reveals that hydrodynamic characteristics of fluid flow inside the channel are entirely changed by the turbulence promoter. The rotational flow pattern increases the scouring effect on the tube wall, reducing the particle deposition on the membrane surface. The absence of stagnant regions and high wall shear stress are respon-sible for the enhanced filtration performance. No secondary flow is generated in the channel, owing to the streamline shape of helical screw insert, so that the enhanced performance is achieved at relatively low energy consumption.

Key words: membrane fouling, flux enhancement, turbulence promoter, computational fluid dynamics

摘要： This paper reports experimental and computational fluid dynamics (CFD) studies on the performance of microfiltration enhanced by a helical screw insert. The experimental results show that the use of turbulence pro-moter can improve the permeate flux of membrane in the crossflow microfiltration of calcium carbonate suspension, and flux improvement efficiency is strongly influenced by operation conditions. The energy consumption analysis indicates that the enhanced membrane system is more energy saving at higher feed concentrations. To explore the intrinsic mechanism of flux enhancement by a helical screw insert, three-dimensional CFD simulation of fluid flow was implemented. It reveals that hydrodynamic characteristics of fluid flow inside the channel are entirely changed by the turbulence promoter. The rotational flow pattern increases the scouring effect on the tube wall, reducing the particle deposition on the membrane surface. The absence of stagnant regions and high wall shear stress are respon-sible for the enhanced filtration performance. No secondary flow is generated in the channel, owing to the streamline shape of helical screw insert, so that the enhanced performance is achieved at relatively low energy consumption.

关键词: membrane fouling, flux enhancement, turbulence promoter, computational fluid dynamics