Characterization and Optimization of a Three-Dimensional T-Type Micromixer for Convective Mixing Enhancement With Reduced Pressure Loss

Abstract

Numerical simulations and experiments are used to evaluate the flow and mixing characteristics of a proposed convective 3-D T-type micromixer. The study presents a parametric study and performance optimization of this micromixer based on the variation of its geometry. To investigate the effect of design and operation parameters on the device performance, a systematic design and optimization methodology is applied; it combines Computational Fluid Dynamics (CFD) with an optimization strategy that integrates Design of Experiments (DOE), Surrogate modeling (SM) and Multi-Objective Genetic Algorithm (MOGA) techniques. The degree of mixing and the pressure loss in the mixing channel are the performance criteria to identify optimum designs at different Reynolds numbers (Re). The convective flow generated in the 3-D T-type micromixer drastically enhances mixing at Re > 100 by making the two fluids to roll up along the mixing channel. The resulting optimum designs are fabricated on polymethylmethacrylate (PMMA) by CNC micromachining. Experiments are carried out to visualize the streams of de-ionized water and aqueous fluorescein solution, by which the extent of mixing is determined, based on the standard deviation of fluorescein intensities on cross-section images. This study applies a systematic procedure for evaluation and optimization of a proposed 3-D T-mixer which has a configuration of channels that promote convective mixing since the two fluids come into contact. The methodology applied can also be used to efficiently modify and customize current micromixers.

Numerical Study of T-Shaped Micromixers with Vortex-Inducing Obstacles in the Inlet Channels

“…Sultan et al studied flow behavior and mixing in mixers with T-shaped jet inlets for different geometrical parameters [ 32 , 33 ]. Three-dimensional (3D) T-type micromixers with non-aligned inlets were proposed for convective mixing enhancement [ 34 , 35 , 36 ]. Other than the geometric modification of the mixing channel, droplet micromixers [ 37 ], micromixers using ultra-hydrophobic surfaces [ 38 ] and more designs have been proposed by many researchers (see References [ 1 , 2 , 3 ] for reviews of these) to improve the mixing quality in passive micromixers.…”

Evaluation of flow characteristics that give higher mixing performance in the 3-D T-mixer versus the typical T-mixer

“…A c c e p t e d M a n u s c r i p t 3 In the present study, the original geometry of the 3-D T-mixer (aspect ratio of the mixing channel equal to 2.0) [1] has been used to evaluate numerically the flow structures and mixing performance in the device at different Re values. As not only the mixing level achieved in the designs reflects their performance, other important variables such as pressure drop and shear stress have been also evaluated.…”

“…The basic design of the new channel configuration was born from the intuitive idea of a geometry that can promote flow circulations at different flow rates and not merely because of the presence of obstacles in the device or a high flow rate in the mixing channel. Recently, Ansari et al [18] provided a valid experimental test of the concept design originally presented by CortesQuiroz et al [1]. Their work was applied on a particular configuration of the 3-D T-mixer with aspect ratio of the mixing channel equal to 0.9, where only measurements of mixing level were used to compare its performance against that of a simple T-mixer.…”

“…More recently, Matsunaga and Nichino [17] included a pair of antisymmetric barriers in the inlet channels near the junction zone of the T-mixer, which generate angular momentum in the flow inducing a swirling flow structure to improve fluid mixing for Re > 20. In this paper, a new configuration of the T-shaped micromixer, which has been called the 3-D T-mixer [1], is studied. The motivation has been to define a simple channel structure where secondary flows can be generated to enhance mixing but at lower flow rates and, consequently, with lower pressure losses than in the simple planar T-mixer.…”

Mixing Performance of a 3D Micro T-Mixer with Swirl-Inducing Inlets and Rectangular Constriction

“…Cortes-Quiroz et al [ 32 ] introduced a 3D T-mixer, in which the depth of two inlet channels was half of the depth of the mixing channel and the position of two inlet channels was different in terms of the direction of the mixing channel depth. The mixing performance of different configurations of the 3D T-mixer was numerically investigated.…”