Fouling Mitigation via Chaotic Advection in a Flat Membrane Module with a Patterned Surface.

Kyung Tae Kim,Tae Gon Kang,Seon Yeop Jung,Jo Eun Park

doi:10.3390/membranes11100724

Kyung Tae Kim, Tae Gon Kang + Show 2 more

Open Access

https://doi.org/10.3390/membranes11100724

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Journal: Membranes	Publication Date: Sep 23, 2021
Citations: 7	License type: CC BY 4.0

Affiliation: Korea Aerospace University, Dankook University

Abstract

Fouling mitigation using chaotic advection caused by herringbone-shaped grooves in a flat membrane module is numerically investigated. The feed flow is laminar with the Reynolds number () ranging from 50 to 500. In addition, we assume a constant permeate flux on the membrane surface. Typical flow characteristics include two counter-rotating flows and downwelling flows, which are highly influenced by the groove depth at each . Poincaré sections are plotted to represent the dynamical systems of the flows and to analyze mixing. The flow systems become globally chaotic as the groove depth increases above a threshold value. Fouling mitigation via chaotic advection is demonstrated using the dimensionless average concentration () on the membrane and its growth rate. When the flow system is chaotic, the growth rate of drops significantly compared to that predicted from the film theory, demonstrating that chaotic advection is an attractive hydrodynamic technique that mitigates membrane fouling. At each Re, there exists an optimal groove depth minimizing and the growth rate of . Under the optimum groove geometry, foulants near the membrane are transported back to the bulk flow via the downwelling flows, distributed uniformly in the entire channel via chaotic advection.

Highlights

The filtration of foulants such as molecules or fine particles from a feed fluid using membranes is used in many fields, including environmental, chemical, biological, pharmaceutical, and food industries [1,2]
Depending on the relative direction between the feed flow and the permeate flow in a membrane filtration process, filtration is classified into dead-end filtration and crossflow filtration
As for the mass transfer in the filtration module, the focus will be on the effects of two parameters on the concentration distribution on the membrane surface and the growth rate of the wall concentration along the downchannel direction

Summary

Introduction

The filtration of foulants such as molecules or fine particles from a feed fluid using membranes is used in many fields, including environmental, chemical, biological, pharmaceutical, and food industries [1,2]. The present study employs a crossflow filtration module that consists of a flat membrane and a patterned non-permeable solid surface with herringbone-shaped grooves, which stirs the feed fluid via chaotic advection, thereby suppressing fouling and concentration polarization in the crossflow filtration module. This is because chaotic advection leads to chaotic trajectories of fluid particles and foulants, thereby uniformly dispersing the foulants in the channel In this regard, a systematic numerical investigation is carried out to understand the flow characteristics and the mass transport in the crossflow filtration module with a flat membrane and a patterned non-permeable solid surface. As for the mass transfer in the filtration module, the focus will be on the effects of two parameters (i.e., the dimensionless groove depth and the Reynolds number of the bulk flow) on the concentration distribution on the membrane surface and the growth rate of the wall concentration along the downchannel direction.

Governing Equations and Boundary

Governing Equations and Boρunuda⋅ r∇yuCondit∇iopns μ∇ u (2)

Simulation Details

Convergence with Mesh Refinement

Evolution of the Foulant Concentration

Growth Rate of the Wall Concentration

Pressure Loss in the Constant Permeate Flux Mode