A Study on Mixing Efficiency in a Two-Channel Circular Micromixer

2006 ◽  
Vol 22 (4) ◽  
pp. 331-338
Author(s):  
M. Chang ◽  
Y.-H. Hu ◽  
S.-W. Chau ◽  
K.-H. Lin
Keyword(s):  
Three Dimensional ◽  
Numerical Prediction ◽  
Mixing Efficiency ◽  
Experimental Measurements ◽  
Inspection Method ◽  
Flow Rates ◽  
Two Fluids ◽  
Finite Volume Discretization ◽  
Mixing Chamber ◽  
Image Inspection

AbstractThe mixing behavior of a two-channel micromixer with a circular mixing chamber at four different chamber depths and six different flow rates had been investigated. Experiments were implemented with the mixings of two fluids. An image inspection method using the variance of the image gray level contrast as the measurement parameter to determine the mixing efficiency distribution in these mixers. The steady, three-dimensional and laminar flow fields inside the micromixers were also simulated numerically with a finite volume discretization. Through the numerical integration over the chamber depth, the three-dimensional numerical prediction could be compressed into a two-dimensional result, which could be directly used to compare with the experimental measurements. Experimental results show that the measured mixing efficiency is raised with the increase of chamber depth. The numerical prediction of mixing efficiency agreed qualitatively with those obtained from the experimental measurements, while the ratio of the depth to diameter of the mixing chamber is big enough to eliminate the viscosity effect.

Two Fluid Mixing in a Micromixer with Helical Channels and Grooved Surfaces

2013 ◽  
Vol 284-287 ◽  
pp. 2096-2101
Author(s):  
Ya Hui Hu ◽  
Farn Shiun Hwu ◽  
Kao Hui Lin
Keyword(s):  
Pure Water ◽  
Reynolds Numbers ◽  
Acetone Solution ◽  
Mixing Efficiency ◽  
Inspection Method ◽  
Two Fluids ◽  
Biomedical Diagnosis ◽  
Passive Micromixer ◽  
Image Inspection ◽  
Helical Channels

The mixing behavior of two fluids in a passive micromixer with a Y-type inlet and helical fluid channels with herringbone grooves etched into the bottom was studied in a numerical simulation and experiments. The mixing of the pure water and acetone solution prepared with different Reynolds numbers and acetone concentrations was investigated. An image inspection method using the variance in contrast of the image gray level as the measurement parameter was adopted to calculate the mixing efficiency distribution. Inspection results show that the mixing efficiency decreased with the increase in the concentration of the acetone solution, although the mixing efficiency around the outlet reached to a value of 90%, even when the Reynolds numbers of the fluids were as low as Re = 1, and the best efficiency achieved for the case of Re = 10 was over 98%. The results show that it should be possible to apply the proposed micromixer in the field of biomedical diagnosis.

A Novel Three-Dimensional Passive Micromixer with Replaceable Mixing Chamber

2014 ◽  
Vol 513-517 ◽  
pp. 3090-3093
Author(s):  
He Zhang ◽  
Li Tian ◽  
Xiao Wei Han ◽  
Xiao Wei Liu
Keyword(s):  
Numerical Simulation ◽  
Three Dimensional ◽  
Mixing Efficiency ◽  
Mixing Chamber ◽  
Result Show ◽  
Passive Micromixer ◽  
Left And Right

In this paper, we design and fabricate a three-dimensional passive-micromixer with a replaceable mixing chamber. The rectangular mixing chamber has a dimension of 20 mm × 3 mm in length and width and 2 mm in height, the chamber can be fitted with different microstructures to accelerate mixing. Then, we compare the no structure chamber to left and right interdigitated chamber by using numerical simulation, the result show that the mixing efficiency has been significantly improved. The photomicrographs proved the effectiveness of the design finally.

Enhancement of Mixing in a Micro TAS by Micro-Bubble Emission Boiling

2007 ◽  
Author(s):  
H. Kato ◽  
T. Kimura ◽  
K. Yamazaki ◽  
M. Yamaguchi
Keyword(s):  
Heat Flux ◽  
Nucleate Boiling ◽  
Mixing Efficiency ◽  
Sectional Area ◽  
Cross Sectional ◽  
Maximum Heat ◽  
Two Fluids ◽  
Maximum Heat Flux ◽  
Mixing Chamber ◽  
Micro Bubble

The mixing of two fluids is important in enhancing chemical reactions in a micro TAS. Some devices or methods are needed to enhance the mixing, because the Reynolds number is very low, on the order of 1. In the present research, we studied the possibility of using micro-bubble emission boiling. A heater made of a platinum wire of 30 micrometer was installed in a Y-shaped micro-channel whose cross sectional area was 2 mm × 0.5 mm. The heater was directly powered by electric current up to 1.5 A. The maximum heat flux was 7.47 MW/m2, which was well above the burnout heat flux. The subcool was 80 degrees and the velocity of fluid (colored water) was changed from 0.5 to 2.0 mm/s. When micro-bubble emission boiling occurred, the mixing was improved drastically. The mixing efficiency reached above 90% at v = 2.0 mm/s and q = 7.47MW/m2. In contrast, the mixing efficiency was poor in the case of normal nucleate boiling. The effect of the mixing chamber was also examined.

scholarly journals Chaotic Micromixer Based on 3D Horseshoe Transformation

Micromachines ◽  
2019 ◽  
Vol 10 (6) ◽  
pp. 398 ◽  
Author(s):  
He Zhang ◽  
Xin Li ◽  
Rongyan Chuai ◽  
Yingjie Zhang
Keyword(s):  
Convective Diffusion ◽  
Three Dimensional ◽  
Mixing Efficiency ◽  
Inverse Transformation ◽  
Mixing Index ◽  
Chaotic Flow ◽  
Buffer Solutions ◽  
Mixing Chamber ◽  
Microscope Images ◽  
Ph Buffer

To improve the efficiency of mixing under laminar flow with a low Reynolds number (Re), a novel three-dimensional Horseshoe Transformation (3D HT) was proposed as the basis for the design of a micromixer. Compared with the classical HT, the Lyapunov exponent of the 3D HT, which was calculated based on a symbolic dynamic system, proved the chaotic enhancement. Based on the 3D HT, a micromixer with a mixing length of 12 mm containing six mixing units was obtained by sequentially applying “squeeze”, “stretch”, “twice fold”, “inverse transformation”, and “intersection” operations. Numerical simulation and Peclet Number (Pe) calculations indicated that when the squeeze amplitude 0 < α < 1/2, 0 < β < 1/2, the stretch amplitude γ > 4, and Re ≥ 1, the mass transfer in the mixer was dominated by convective diffusion induced by chaotic flow. When Re = 10, at the outlet of the mixing chamber, the simulated mixing index was 96.4%, which was far less than the value at Re = 0.1 (σ = 0.041). Microscope images of the mixing chamber and the curve trend of pH buffer solutions obtained from a mixing experiment were both consistent with the results of the simulation. When Re = 10, the average mixing index of the pH buffer solutions was 91.75%, which proved the excellent mixing efficiency of the mixer based on the 3D HT.

A New Scheme for Improving the Mixing Efficiency in Micro Scale

2011 ◽  
Author(s):  
Ali Mohammad Anbari ◽  
Artin Haroutunian ◽  
Mohammed Said Saidi ◽  
Mohammad Behshad Shafii
Keyword(s):  
Fluid Velocity ◽  
Mixing Efficiency ◽  
Mixing Process ◽  
Layer Potential ◽  
Outlet Cross Section ◽  
Micro Scale ◽  
Two Fluids ◽  
Mixing Chamber ◽  
Micro Channels ◽  
Micro Mixer

Generally speaking, most micro-fluidic mixing systems are limited to the low Reynolds number regime in which diffusion dominates convection, and consequently the mixing process tends to be slow and it takes a relatively long time to have two fluids completely mixed. Therefore, rapid mixing is essential in micro-fluidic systems. In order to hasten the mixing process in micro scale, in this study we come up with a novel scheme for a two dimensional micro-fluidic mixer which encompasses three pairs of electrodes, one pair embedded in the mixing chamber and two pairs located in the micro-channels before and after the mixing chamber. The width of the middle pair is assumed to be twice of the other pairs. In addition, the fluids enter the device via two different entrances within a T-junction. The width of all micro-channels is equal to 50 micrometer and the whole mixer is less than 1 millimeter in length. While Electrical potentials are applied to three electrodes in the outlet and inlet ports in order to conduct the fluids within the mixer, the chaotic electrical fields applied to the mixing chamber are derived by the Duffing-Holmes nonlinear system. We numerically simulate the performance of our micro-mixer by solving Navier-Stokes and continuity equations for fluid velocity field, Poisson-Boltzmann equation for describing the electrical double layer potential distribution, Laplace equation for the externally induced electrical field distribution and concentration transport equation in order to obtain the concentration distribution of two fluids within the geometry. Then, the mixing efficiency is calculated in the outlet cross section of the mixer and the results indicate that a mixing performance efficiency of up to 98% is obtainable by utilizing this proposed scheme.

Flow in Single and Twin Entry Radial Turbine Volutes

1988 ◽  
Author(s):  
N. Lymberopoulos ◽  
N. C. Baines ◽  
N. Watson
Keyword(s):  
Three Dimensional ◽  
Experimental Measurements ◽  
Axial Component ◽  
Flow Properties ◽  
Internal Wall ◽  
Dimensional Solution ◽  
Flow Rates ◽  
Radial Turbine ◽  
Partial Admission ◽  
Single Entry

This paper presents a numerical analysis and experimental measurements of flows in the vaneless volute of a radial–inflow turbine. Cases of single and twin entry to the volute were studied, and in particular the case of unequal flows, or partial admission, to the two entries. The distance between the rotor tip and the limit of the internal wall separating the two flows was varied in order to study the effects of interaction of the two streams. The computational model is based on a quasi–three–dimensional solution of the Euler equations, in which the radial and tangential components of velocity are fully solved, but the axial component is only treated to simulate the mixing of the two streams. The results of the model were compared with published results for a single entry, and extensive new results for a single or twin entry, casing. Even in the single and equal flow twin–entry cases, significant variations in flow properties around the exit circumference of the volutes were observed, most particularly in the region of re–entry near the tongue. For unequal flows the interaction of the two streams was strong and increased with increasing separating wall diameter, and with increasing inequality of flow rates. In extreme cases the flow reverses.

A Low Temperature Co-Fired Ceramic Microfluidic Cell Counter

2014 ◽  
Vol 592-594 ◽  
pp. 2261-2266
Author(s):  
A. Priya Rathi ◽  
A. Vimala Juliet
Keyword(s):  
Low Temperature ◽  
Saline Solution ◽  
Three Dimensional ◽  
Comsol Multiphysics ◽  
Mixing Efficiency ◽  
Electrode Pair ◽  
Two Fluids ◽  
Microfluidic Biosensor ◽  
A Cell ◽  
Cell Counter

A three-dimensional microfluidic biosensor has been successfully designed using a low temperature co-fired ceramic (LTCC) technology. This microfluidic sensor consists of mixing, focusing and measuring region. The mixing region is a rectangular shaped channel, to enable the complete mixing of sample and buffered saline solution. An electrode pair in the focusing region uses negative dielectrophoretic forces to direct the cells from all directions of the channel towards the center. The measuring region consists of eleven pairs of gold plated electrodes to measure the change in impedance whenever a cell passes through it. The layout of the design is made using AUTOCAD tool and simulated using COMSOL Multiphysics. The results demonstrate the mixing efficiency of two fluids for different velocities.

An experience of elaboration and implementation of systems of slag-forming mixtures mechanized feeding into CCM moulds

2020 ◽  
Vol 76 (10) ◽  
pp. 994-1003
Author(s):  
S. P. Eron’ko ◽  
M. Yu. Tkachev ◽  
E. V. Oshovskaya ◽  
B. I. Starodubtsev ◽  
S. V. Mechik
Keyword(s):  
Economic Effect ◽  
Three Dimensional ◽  
Movable Part ◽  
High Quality ◽  
Working Zone ◽  
Fine Material ◽  
Mixing Chamber ◽  
Field Samples ◽  
Technical Solutions ◽  
Feeding Systems

Effective application of slag-forming mixtures (SFM), being fed into continuous castingg machine (CCM) moulds, depends on their even distribution on the melt surface. Manual feeding of the SFM which is widely usedd does not provide this condition, resulting in the necessity to actualize the work to elaborate systems of SFM mechanized feedingg into moulds of various types CCM. A concept of the designing of a system of SFM feeding into CCM moulds presented with the ratte strictly correspondent to the casting speed and providing formation of an even layer of fine material of given thickness on the whoole surface of liquid steel. The proposed methods of designing of the SFM mechanized feeding systems based on three-dimensional computer simulation with the subsequent verification of the correctness of the adopted technical solutions on field samples. Informattion is presented on the design features of the adjusted facilities intended for continuous supply of finely granulated and powder mixtuures on metal mirror in moulds at the production of high-quality billets, blooms and slabs. Variants of mechanical and pneumo-mechaanical SFM supply elaborated. At the mechanical supply the fine material from the feeding hopper is moved at a adjusted distance bby a rigid horizontally located screw. At the pneumo-mechanical supply the metered doze of the granular mixture is delivered by a sshort vertical screw, the lower part of which is located in the mixing chamber attached from below to the hopper and equipped with ann ejector serving for pneumatic supply of the SFM in a stream of transporting gas. It was proposed to use flexible spiral screws in the ffuture facilities of mechanical SFM feeding. It will enable to eliminate the restrictions stipulated by the lack of free surface for locatiion of the facility in the working zone of the tundish, as well as to decrease significantly the mass of its movable part and to decreaase the necessary power of the carriage moving mechanism driver. The novelty of the proposed technical solutions is protected by thhree patents. The reduction of 10–15% in the consumption of slag-forming mixtures during the transition from manual to mechanizeed feeding confirmed. The resulting economic effect from the implementation of technical development enables to recoup the costs inncurred within 8–10 months.

scholarly journals A Numerical Study of Sub-Millisecond Integrated Mix-and-Inject Microfluidic Devices for Sample Delivery at Synchrotron and XFELs

2021 ◽  
Vol 11 (8) ◽  
pp. 3404
Author(s):  
Majid Hejazian ◽  
Eugeniu Balaur ◽  
Brian Abbey
Keyword(s):  
Molecular Dynamics ◽  
Flow Rate ◽  
Numerical Study ◽  
Three Dimensional ◽  
Microfluidic Devices ◽  
Liquid Jets ◽  
Mixing Efficiency ◽  
X Ray Diffraction ◽  
Cross Sectional ◽  
Time Required

Microfluidic devices which integrate both rapid mixing and liquid jetting for sample delivery are an emerging solution for studying molecular dynamics via X-ray diffraction. Here we use finite element modelling to investigate the efficiency and time-resolution achievable using microfluidic mixers within the parameter range required for producing stable liquid jets. Three-dimensional simulations, validated by experimental data, are used to determine the velocity and concentration distribution within these devices. The results show that by adopting a serpentine geometry, it is possible to induce chaotic mixing, which effectively reduces the time required to achieve a homogeneous mixture for sample delivery. Further, we investigate the effect of flow rate and the mixer microchannel size on the mixing efficiency and minimum time required for complete mixing of the two solutions whilst maintaining a stable jet. In general, we find that the smaller the cross-sectional area of the mixer microchannel, the shorter the time needed to achieve homogeneous mixing for a given flow rate. The results of these simulations will form the basis for optimised designs enabling the study of molecular dynamics occurring on millisecond timescales using integrated mix-and-inject microfluidic devices.

scholarly journals Geometrical Optimization of a Venturi-Type Microbubble Generator Using CFD Simulation and Experimental Measurements

Designs ◽  
2021 ◽  
Vol 5 (1) ◽  
pp. 4
Author(s):  
Dillon Alexander Wilson ◽  
Kul Pun ◽  
Poo Balan Ganesan ◽  
Faik Hamad
Keyword(s):  
Water Flow ◽  
Flow Rate ◽  
Cfd Simulation ◽  
Air Flow ◽  
Bubble Diameter ◽  
Diameter Ratio ◽  
Experimental Measurements ◽  
Cfd Model ◽  
Flow Rates ◽  
Throat Diameter

Microbubble generators are of considerable importance to a range of scientific fields from use in aquaculture and engineering to medical applications. This is due to the fact the amount of sea life in the water is proportional to the amount of oxygen in it. In this paper, experimental measurements and computational Fluid Dynamics (CFD) simulation are performed for three water flow rates and three with three different air flow rates. The experimental data presented in the paper are used to validate the CFD model. Then, the CFD model is used to study the effect of diverging angle and throat length/throat diameter ratio on the size of the microbubble produced by the Venturi-type microbubble generator. The experimental results showed that increasing water flow rate and reducing the air flow rate produces smaller microbubbles. The prediction from the CFD results indicated that throat length/throat diameter ratio and diffuser divergent angle have a small effect on bubble diameter distribution and average bubble diameter for the range of the throat water velocities used in this study.

Sign in / Sign up

Export Citation Format

Share Document