scholarly journals Asymmetric Y-shaped Micromixers with Spherical Mixing Chamber for Enhanced Mixing Efficiency and Reduced Flow Impedance

2021 ◽  
Vol 14 (5) ◽  
Keyword(s):  
Mixing Efficiency ◽  
Mixing Chamber ◽  
Flow Impedance ◽  
Reduced Flow

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.

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.

Triple-Choking Model for Ejector

2010 ◽  
Vol 2 (2) ◽  
Author(s):  
J. Sargolzaei ◽  
M. R. Pirzadi Jahromi ◽  
E. Saljoughi
Keyword(s):  
Theoretical Models ◽  
Mixing Efficiency ◽  
Governing Equations ◽  
Critical Mode ◽  
Cross Sectional ◽  
New Approach ◽  
Mode Operation ◽  
Operation Conditions ◽  
Mixing Chamber ◽  
Good Agreement

In this study, a 1D analysis has been presented for the prediction of ejector performance at critical mode operation. The new triple-choking model has been developed using the governing equations of the compressible fluids and thermodynamics properties based on the frictional adiabatic fluid study. A new approach has been introduced to consider the frictional effects on the mixing efficiencies by extending the 1D ejector theory. A very good agreement has been reported for the R141b and steam experimental data at critical mode operation. Furthermore, simulated results have been compared with some of the recent theoretical models. In addition, the influence of operation conditions on the ejector performance and the required cross-sectional area of the mixing chamber has been showed. Finally, the influence of the operation conditions (such as generator, condenser, and evaporator temperatures) and the size of ejector on the mixing efficiency have been studied.

scholarly journals Study on the Expansion of Primary Flow for the Mixing Uniformity in the Two-Phase Ejector

2021 ◽  
Vol 2097 (1) ◽  
pp. 012012
Author(s):  
Lixing Zheng ◽  
Hongwei Hu ◽  
Changning Mi
Keyword(s):  
Secondary Flow ◽  
Optimization Design ◽  
Entropy Change ◽  
Mixing Efficiency ◽  
Primary Flow ◽  
Two Phase ◽  
Operation Conditions ◽  
Thermodynamic Entropy ◽  
Mixing Chamber ◽  
Flow Pressure

Abstract The expansion of primary flow in the suction chamber of the CO2 two-phase ejector is investigated and its influences on the mixing characteristics are analyzed. An ejector model is developed, by constructing differential equations for mass, momentum and energy then get the governing equation. In the suction chamber, the expansion of primary flow and the compression of secondary flow are modeled along the flow path. Based on the constant-pressure mixing theory, the pressure equilibrium positions of two stream (namely at the inlet and inside of mixing chamber, respectively) are considered. The mass and energy transfer in the mixing chamber were analyzed by using the double-flow model formulation. The ejector performance parameters are obtained for the different operation conditions, and the distributions of temperature and velocity of two streams in the mixing chamber are presented. The simulation results showed the influence of primary flow expansion on the pressure lift ratio was relatively obvious, and the larger expansion distance was helpful to improve the mixing efficiency and decrease the thermodynamic entropy change during the mixing. Moreover, the temperature of secondary flow for lower primary flow pressure presented larger descent rates at the initial of mixing. This work is helpful for the improvement of ejector theoretical model and the optimization design.

scholarly journals CFD Analysis Diesel Spray Mixing Nozzle in Various Angle

2021 ◽  
Vol 12 (1S) ◽  
pp. 478-490
Author(s):  
N.Kalaimani, Et. al.
Keyword(s):  
Spray Angle ◽  
Diesel Spray ◽  
Mixing Efficiency ◽  
Cfd Analysis ◽  
Mixing Ratios ◽  
Mixing Chamber ◽  
Ic Engines

The main objective of this project is finding the optimized mixed ratio of the diesel spray mixer in the IC Engines, CFD Methodology is used for this analysis the spray angle variations give the various mixing ratios of the sprayer for better combustion ratios the turbulence will decide the best mixing efficiency, the turbulence, pressure and velocity results inside the mixing chamber is analyze through CFD methodology

Investigation of Fill Factor in Two-Wing Rotor Mixing of Rubber by Using Computational Fluid Dynamics

2017 ◽  
Vol 45 (2) ◽  
pp. 144-160 ◽  
Author(s):  
Pashupati Dhakal ◽  
Suma R. Das ◽  
Abhilash J. Chandy
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
High Performance ◽  
Fill Factor ◽  
Industrial Process ◽  
Coupling Reaction ◽  
Operating Regime ◽  
Mixing Efficiency ◽  
Operating Variables ◽  
Mixing Chamber

ABSTRACT The industrial process of manufacturing tires brings together all the ingredients required to mix a batch of rubber compound in an operation called mixing. The development and use of mixing in a mixing chamber equipped with a rotor has a significant impact on the process itself, and understanding mixing is important in terms of evaluating how material, mixer design, and operating variables (e.g., rpm, temperature, ram pressure) affect distribution, dispersion, and coupling reaction. One of the most important factors to consider is the fill factor, which is the volume of the material relative to the volume of the chamber. It is critical to determine the operating regime in terms of the level of mixing material in the chamber to satisfy all the mixing requirements of the process. Furthermore, the availability of modern high-performance computing resources and accurate mathematical models makes computational fluid dynamics (CFD) an important and necessary tool in understanding some of the complex physical and chemical phenomena associated with such industrial manufacturing problems. The objective of this paper is to assess the effect of fill factor in a two-wing rotor geometry that is used for rubber compounds mixing in the tire manufacturing process and thereby determine the best fill factor with regard to providing the highest mixing efficiency. A series of 3D CFD simulations in a mixing chamber with fill factors of 45, 60, 75, 90, and 100%, stirred by counter-rotating rotors, were carried out using a CFD code. Flow patterns, mixing index, particle trajectories, and statistics such as segregation scale, length of stretch, and pairwise distribution are presented to understand the mixing process with a long-term goal of improving product quality and throughput. Results showed that the major mixing mechanism is shear for most of the fill factors and that the 75% fill factor has the best distributive mixing characteristics among the fill factors studied here.

Flow Mechanism of a Novel Active Micro-Rotor Mixer

2012 ◽  
Vol 488-489 ◽  
pp. 1177-1183
Author(s):  
Y.C. Liou ◽  
J.M. Miao ◽  
T.L. Liu ◽  
S.J. Cheng
Keyword(s):  
Reynolds Number ◽  
Vortex Flow ◽  
Pure Water ◽  
Inertial Force ◽  
Flow Patterns ◽  
Mixing Efficiency ◽  
Working Fluids ◽  
Rotating Speed ◽  
Mixing Chamber ◽  
Micro Mixer

The purpose of this study is to investigate the complex vortex flow patterns within a novel active micro-rotor mixer under various Reynolds numbers and rotating speeds by employing of CFD technique. The concept of present micro-rotor mixer is inspired from the Wankel-type combustor which is widely used in the power machines. The configuration of present micro-mixer is consisted of a rotor with shape of triangle column, a blending chamber and individual inlet and outlet ports. The blending chamber is served as the mixing chamber since the separated three sub-regions will change their volumes as the rotor undergoing the rotating motion with a fixed eccentricity. The dynamic flow patterns and mixing process of two species within the mixing chamber were simulated and visualized with streak lines. The governing equations are unsteady, two-dimensional incompressible Navier-Stokes equation and the two working fluids are pure water and alcohol. The concentration equation for species is also solved to reveal the mass transfer process in various sub-regions then being calculated on the outlet port to evaluate the mixing efficiency. The dynamic mesh technique was applied to re-distribute the computational meshes when the rotor finished a complete rotation cycle. Inspection on the flow developing stages within the mixing chamber over one complete cycle, it seems that multi-vortex flow field was generated due to the interaction of the shear force from the rotor, viscous force and inertial force of working fluids. The Coanda flow appeared in some conditions. When the Reynolds number is below of 10, the rotating speed of rotor has less influence on the mixing efficiency. An obvious enhancement in the mixing efficiency can be found in cases of the rotating speed of rotor changed from 30 rpm to 150 rpm when the Reynolds number in range of 25 to 100. Generally, the maximum mixing efficiency of 85% can be achieved for 1<Re<100 which demonstrated that present design was effective for μ-TAS.

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.

RGB Color Model Analysis for a Simple Structured Polydimethylsiloxane Pneumatic Micromixer

2021 ◽  
pp. 247263032110088
Author(s):  
Xuling Liu ◽  
Duanqin Zhang ◽  
Jie Liu ◽  
Liangwen Wang ◽  
Songjing Li
Keyword(s):  
Simple Structure ◽  
Model Analysis ◽  
Mixing Efficiency ◽  
Color Model ◽  
Microfluidic Chips ◽  
Mixing Chamber ◽  
Pneumatic Chamber ◽  
Conventional Methods

This article reports mixability experiments and their RGB color model analysis for a simple structured micromixer based on the pneumatic-driven membrane in multiple microreagent mixing applications. First, a novel and simple structure consisting of a mixing chamber and a pneumatic chamber is designed and fabricated of polydimethylsiloxane (PDMS) material, which facilitates integration with microfluidic chips. Then, experiment results and their RGB color model about mixing efficiency are investigated. Compared with conventional methods, the RGB color model for mixing results is easy and intuitive. In addition, the designed micromixer operation relies on less external laboratory infrastructure because of its simple structure.

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