Abstract
In this study, we report on a numerical study on design optimization for a microfluidic crossflow filtration system incorporated with the staggered herringbone micromixer (SHM). Computational fluid dynamics (CFD) and the Taguchi method were employed to find out an optimal set of design parameters, mitigating fouling in the filtration system. The flow and the mass transfer characteristics in a reference SHM model and a plain rectangular microchannel were numerically investigated in detail. Downwelling flows in the SHM model lead to backtransport of foulants from the permeable wall, which slows down the development of the concentration boundary layer in the filtration system. Four design parameters — the number of grooves, the groove depth, the interspace between two neighboring grooves, and the interspace between half mixing periods — were chosen to construct a set of numerical experiments using an orthogonal array from the Taguchi method. The Analysis of Variance (ANOVA) using the evaluated signal-to-noise (SN) ratios enabled us to identify the contribution of each design parameter on the performance. The proposed optimal SHM model indeed showed the lowest growth rate of the wall concentration compared to other SHM models.
Highlights
Membrane filtration is widely used in a variety of areas, e.g., wastewater treatment, chemical and biological industries, food industry, pharmaceutical industry, and microfluidics [1,2,3,4]
In previous studies [36,37], it was demonstrated that, with a micromixer incorporated with a microfluidic membrane filtration system, the permeate flux could be significantly improved via chaotic mixing that reduces the amount of fouling on membrane surfaces
The objective function in the design optimization of the microfluidic filtration system is to minimize the development of the wall concentration on the permeable region
Summary
Membrane filtration is widely used in a variety of areas, e.g., wastewater treatment, chemical and biological industries, food industry, pharmaceutical industry, and microfluidics [1,2,3,4]. In the crossflow filtration, such flow instabilities, occurring in coiled or twisted tubular membranes, increase the backtransport of solute or foulants away from the membrane surface, leading to enhanced permeate fluxes [17,18,19,20]. Another hydrodynamic technique to enhance filtration performance is the use of inserts. In previous studies [36,37], it was demonstrated that, with a micromixer incorporated with a microfluidic membrane filtration system, the permeate flux could be significantly improved via chaotic mixing that reduces the amount of fouling on membrane surfaces.
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