Fabrication of Microfluidic Rapid Micromixer

2011 ◽  
Vol 467-469 ◽  
pp. 2013-2017
Author(s):  
Hsiang Chen Hsu ◽  
Hsi Chien Liu ◽  
Cheng Jiun Han
Keyword(s):  
Flow Rate ◽  
Fluid Velocity ◽  
Volumetric Flow Rate ◽  
Mixing Efficiency ◽  
Mixing Index ◽  
Micro Pump ◽  
Chaotic Convection ◽  
Wide Range ◽  
Parametric Studies ◽  
Junction Type

A microfluidic multi-cylindric rapid micromixer is fabricated in the present paper. The key features in the presented MEMS-based microchannel design are (1) micro pump (2) Y-junction type channel (3) cylindric obstacle (4) notch with the edge of sharp teeth. Two different fluids (DI water and red ink) were pumped and injected into Y-type channel, and the fluids were broken-up by a cylindric obstacle in the center of tapered microchannel. The chaotic convection occurs in the mixing channel behind the cylindric obstacle. The mixing index is defined to qualify the mixing efficiency, which demonstrates the outlet notch with sharp teeth along the sidewall plays an important role for mixing effects. The developed micromixer can enhance mixing using the mechanisms of diffusion and convection for wide range of Reynolds number (0.01<Re<100). Parametric studies for volumetric flow rate include the number of cylindric obstacles, the number of notches with sharp-teeth and the width of microchannel. Preliminary results demonstrate that the mixing index reaches the desired effect (<0.1) within 0.08 second when the inlet fluid velocity is 0.49992m/s, i.e. volumetric flow rate is 1200μl /min. The presented device is faster than most of reported micromixers.

scholarly journals Analytical Solution for Heat Transfer in Electroosmotic Flow of a Carreau Fluid in a Wavy Microchannel

2019 ◽  
Vol 9 (20) ◽  
pp. 4359 ◽  
Author(s):  
Saima Noreen ◽  
Sadia Waheed ◽  
Abid Hussanan ◽  
Dianchen Lu
Keyword(s):  
Fluid Flow ◽  
Flow Pattern ◽  
Flow Rate ◽  
Electroosmotic Flow ◽  
Linear Problem ◽  
Perturbation Technique ◽  
Volumetric Flow Rate ◽  
Carreau Fluid ◽  
Long Wavelength ◽  
Wide Range

This article explores the heat and transport characteristics of electroosmotic flow augmented with peristaltic transport of incompressible Carreau fluid in a wavy microchannel. In order to determine the energy distribution, viscous dissipation is reckoned. Debye Hückel linearization and long wavelength assumptions are adopted. Resulting non-linear problem is analytically solved to examine the distribution and variation in velocity, temperature and volumetric flow rate within the Carreau fluid flow pattern through perturbation technique. This model is also suitable for a wide range of biological microfluidic applications and variation in velocity, temperature and volumetric flow rate within the Carreau fluid flow pattern.

Comprehensive analysis of the thermohydraulic performance of cooling networks subject to fouling and undergoing retrofit projects

2020 ◽  
pp. 0958305X2094531
Author(s):  
Hebert Lugo-Granados ◽  
Lázaro Canizalez-Dávalos ◽  
Martín Picón-Núñez
Keyword(s):  
Pressure Drop ◽  
Water Flow ◽  
Flow Rate ◽  
Fluid Velocity ◽  
Water Flow Rate ◽  
Volumetric Flow Rate ◽  
Cooling Capacity ◽  
Point Of View ◽  
Rate Distribution

The aim of this paper is to develop guidelines for the placing of new coolers in cooling systems subject to retrofit. The effects of the accumulation of scale on the flow system are considered. A methodology to assess the interconnected effect of local fluid velocity and fouling deposition is developed. The local average fluid velocity depends on the water flow rate distribution across the piping network. The methodology has four main calculation components: a) the determination of the flow rate distribution across the piping network, b) the prediction of fouling deposition, c) determination of the hydraulic changes and the effect on fouling brought about by the placing of new exchangers into an existing structure, and d) the calculation of the total cooling load and pressure drop of the system. The set of disturbances introduced to the system through fouling and the incorporation of new coolers, create network responses that eventually influence the cooling capacity and the pressure drop. In this work, these interactions are analysed using two case studies. The results indicate that, from the thermal point of view, the incorporation of new heat exchangers is recommended in series. The limit is the point where the increase of the total pressure drop causes a reduction in the overall volumetric flow rate. New coolers added in parallel create a reduction of pressure drop and an increase in the overall water flow rate; however, this increase is not enough to counteract the reduction of fluid velocity and heat capacity removal.

scholarly journals Volumetric flow rate in simulations of microfluidic devices

2018 ◽  
Vol 180 ◽  
pp. 02046
Author(s):  
KristÍna Kovalčíková ◽  
Martin Slavík ◽  
Katarína Bachratá ◽  
Hynek Bachratý ◽  
Alžbeta Bohiniková
Keyword(s):  
External Force ◽  
Flow Rate ◽  
Laboratory Experiments ◽  
Fluid Velocity ◽  
Volumetric Flow Rate ◽  
Microfluidic Devices ◽  
Fixed Set ◽  
Volumetric Rate ◽  
Simulation Parameter ◽  
Set Up

In this work, we examine the volumetric flow rate of microfluidic devices. The volumetric flow rate is a parameter which is necessary to correctly set up a simulation of a real device and to check the conformity of a simulation and a laboratory experiments [1]. Instead of defining the volumetric rate at the beginning as a simulation parameter, a parameter of external force is set. The proposed hypothesis is that for a fixed set of other parameters (topology, viscosity of the liquid, …) the volumetric flow rate is linearly dependent on external force in typical ranges of fluid velocity used in our simulations. To confirm this linearity hypothesis and to find numerical limits of this approach, we test several values of the external force parameter. The tests are designed for three different topologies of simulation box and for various haematocrits. The topologies of the microfluidic devices are inspired by existing laboratory experiments [3 - 6]. The linear relationship between the external force and the volumetric flow rate is verified in orders of magnitudes similar to the values obtained from laboratory experiments.

scholarly journals CFD Modelling of Global Mixing Parameters in a Peirce-Smith Converter with Comparison to Physical Modelling

2011 ◽  
Vol 6 (1) ◽  
Author(s):  
Deside K Chibwe ◽  
Guven Akdogan ◽  
Chris Aldrich ◽  
Rauf H Eric
Keyword(s):  
Flow Rate ◽  
Volume Fraction ◽  
Mixing Time ◽  
Volumetric Flow Rate ◽  
Numerical Code ◽  
Mixing Efficiency ◽  
Phase System ◽  
Cfd Modelling ◽  
Cold Model ◽  
Peirce Smith Converter

The flow pattern and mixing in an industrial Peirce-Smith converter (PSC) has been experimentally and numerically studied using cold model simulations. The effects of air volumetric flow rate and presence of overlaying slag phase on matte on the flow structure and mixing were investigated. The 2-D and 3-D simulations of the three phase system were carried out using volume of fluid (VOF) and realizable k - ɛ turbulence model to account for the multiphase and turbulence nature of the flow respectively. These models were implemented using commercial Computational Fluid Dynamics (CFD) numerical code FLUENT. The cold model for physical simulations was a 1:5 horizontal cylindrical container made of Perspex with seven tuyeres on one side of the cylinder typifying a Peirce-Smith converter. Compressed air was blown into the cylinder through the tuyeres, simulating air or oxygen enriched air injection into the PSC. The matte and slag phases were simulated with water and kerosene respectively in this study. The influence of varying blowing conditions and simulated slag quantities on the bulk mixing was studied with five different air volumetric flow rates and five levels of simulated slag thickness. Mixing time results were evaluated in terms of total specific mixing power and two mixing time correlations were proposed for estimating mixing times in the model of PSC for low slag and high slag volumes. Both numerical and experimental simulations were in good agreement to predict the variation characteristics of the system in relation to global flow field variables set up in the converter through mathematical calculation of relevant integrated quantities of turbulence, Volume Fraction (VF) and velocity magnitudes. The findings revealed that both air volumetric flow rate and presence of the overlaying slag layer have profound effects on the mixing efficiency of the converter.

scholarly journals Modeling of mixing for stirred bioreactors: 3. Mixing time for aerated simulated broths

2002 ◽  
Vol 56 (12) ◽  
pp. 506-513 ◽  
Author(s):  
Dan Cascaval ◽  
Corneliu Oniscu ◽  
Anca-Irina Galaction ◽  
Fiorina Ungureanu
Keyword(s):  
Flow Rate ◽  
Rotation Speed ◽  
Mixing Time ◽  
Volumetric Flow Rate ◽  
Mixing Efficiency ◽  
Complex Flow ◽  
Average Deviation ◽  
Stirred Bioreactor ◽  
Stirred Bioreactors ◽  
Turbine Impeller

This paper presents the experiments on mixing efficiency for aerated media for a laboratory stirred bioreactor with a double turbine impeller. The effects of stirrer rotation speed, air volumetric flow rate and stirrer position on the shaft on mixing time for aerated water and simulated broths (CMCNa solutions) were analyzed. Compared to non-aerated broths, the results indicated that the variation of mixing time with the considered parameters is very different, due to the complex flow mechanism of the gas-liquid dispersion, a mechanism which is changed by changing the broth properties or fermentation conditions. Using the Statistics Toolbox of MATLAB some correlations between the mixing time and rotation speed, air volumetric flow rate and stirrer position on the shaft were established. The proposed equations agree well with the experiments, the average deviation being ?9.02%.

Thermal Bubble Microfluidic Gate Based on SOI Wafer

2009 ◽  
Author(s):  
Chingfu Tsou ◽  
Chenghan Huang
Keyword(s):  
Flow Rate ◽  
Applied Voltage ◽  
Vapor Bubble ◽  
Rectangular Cross Section ◽  
Fluid Velocity ◽  
Side Wall ◽  
Bubble Nucleation ◽  
Mixing Efficiency ◽  
Vertical Side ◽  
Silicon Based

This paper presents a simple process using an SOI wafer to fabricate a silicon-based vertical microheater to generate thermal bubbles for the applications in microfluidic systems. The fabrication process consists of only two photolithography masks that provide an effective way to manufacture a resistive bulk microheater and high-aspect-ratio microchannel. The electro-thermal property of the proposed microheater has been characterized and verified by finite element analysis and experiment. According to the design concept and experimental results, the largest temperature occurred at the smallest neck section due to the non-uniform property of the resistance along the length of the arch-type microheater, and thus the vapor bubble was generated and attached on the vertical side wall of the microheater. For a typical microheater design, bubble nucleation could be generated under the applied voltage of 5V and the bubble could obstruct the entire 100 μm width of the microchannel when the applied voltage reaches 8V. A switching test has showed the silicon-based microheater has a good thermal-resistance behavior for long-term reliability and the modulation of output flow rate is easy handled by the sizes of thermal bubble. Moreover, the bubble can be formed with a steady growth even when the maximum fluid velocity is larger than 920 μm/s in a microchannel with rectangular cross-section 100 μm wide and 50 μm high. Mixing performance of the thermal bubble to disturb two collateral liquids with lamina flow was also carried out in this work. Experiments show that a high mixing efficiency could be achieved when the vapor bubble was formed in a 100 μm wide, 50 μm deep microchannel with a flow rate of 780 μm/s. These results reveal that the microfluid gate presented here is well designed and bubble sizes are stable and controllable.

Multieffects on Mixing Quality of an Active Micromixer

2007 ◽  
Author(s):  
Thien X. Dinh ◽  
Yoshifumi Ogami
Keyword(s):  
Flow Rate ◽  
Pressure Loss ◽  
Rotation Speed ◽  
Mixing Efficiency ◽  
Mean Velocity ◽  
Mixing Performance ◽  
Convective Mixing ◽  
Wide Range ◽  
Computational Fluid Dynamics Cfd

The convective mixing performance of an active micromixer is analyzed by using computational fluid dynamics (CFD). The mixer consists of a Y-shaped channel and an N-paddle (3, 4, and 5) rotor with radius R suspended in the junction of the channel. Numerical simulations are performed for a wide range of rotation speed of the rotor, ω, and mean velocity in the mixer, U. The asymptotic mixing performance is investigated by means of Lagrangian particle tracking simulation, stretching of a material line, dispersive and distributive mixing efficiencies. The results show that the mixing performance depends on the combined variable ωR/U, whereas paddle number has ignorable effects. Physically, the convective ratio of rotation speed to mean velocity governs the mixing process in the mixer. Contrastively, paddle number affects significantly to pressure loss and fluid torque exercising on the rotor. The time-averaged fluid torque depends linearly on rotation speed regardless of flow rate. Pressure loss relates linearly to flow rate, negligibly to rotation speed. It shows that a smaller paddle number produces lesser pressure loss and fluid torque for the same mixing efficiency.

scholarly journals An Investigation into the Volumetric Flow Rate Requirement of Hydrogen Transportation in Existing Natural Gas Pipelines and Its Safety Implications

Gases ◽  
2021 ◽  
Vol 1 (4) ◽  
pp. 156-179
Author(s):  
Abubakar Jibrin Abbas ◽  
Hossein Hassani ◽  
Martin Burby ◽  
Idoko Job John
Keyword(s):  
Natural Gas ◽  
Flow Rate ◽  
Compressibility Factor ◽  
Volumetric Flow Rate ◽  
Gas Pipeline ◽  
Internal Erosion ◽  
Gas Pipelines ◽  
Natural Gas Pipelines ◽  
Natural Gas Pipeline ◽  
Wide Range

As an alternative to the construction of new infrastructure, repurposing existing natural gas pipelines for hydrogen transportation has been identified as a low-cost strategy for substituting natural gas with hydrogen in the wake of the energy transition. In line with that, a 342 km, 36″ natural gas pipeline was used in this study to simulate some technical implications of delivering the same amount of energy with different blends of natural gas and hydrogen, and with 100% hydrogen. Preliminary findings from the study confirmed that a three-fold increase in volumetric flow rate would be required of hydrogen to deliver an equivalent amount of energy as natural gas. The effects of flowing hydrogen at this rate in an existing natural gas pipeline on two flow parameters (the compressibility factor and the velocity gradient) which are crucial to the safety of the pipeline were investigated. The compressibility factor behaviour revealed the presence of a wide range of values as the proportions of hydrogen and natural gas in the blends changed, signifying disparate flow behaviours and consequent varying flow challenges. The velocity profiles showed that hydrogen can be transported in natural gas pipelines via blending with natural gas by up to 40% of hydrogen in the blend without exceeding the erosional velocity limits of the pipeline. However, when the proportion of hydrogen reached 60%, the erosional velocity limit was reached at 290 km, so that beyond this distance, the pipeline would be subject to internal erosion. The use of compressor stations was shown to be effective in remedying this challenge. This study provides more insights into the volumetric and safety considerations of adopting existing natural gas pipelines for the transportation of hydrogen and blends of hydrogen and natural gas.

scholarly journals Effect of magnetic field on Newtonian fluid sandwiched between non-Newtonian fluids through porous cylindrical shells

2021 ◽  
Author(s):  
Deepak Kumar Maurya ◽  
Satya Deo
Keyword(s):  
Magnetic Field ◽  
Newtonian Fluid ◽  
Flow Rate ◽  
Hartmann Number ◽  
Viscosity Ratio ◽  
Fluid Velocity ◽  
Fluid Motion ◽  
Volumetric Flow Rate ◽  
Shear Stresses ◽  
Micropolar Fluids

Abstract The present work deals with the influence of magnetic field on Newtonian fluid sandwiched between two porous cylindrical pipes which are filled with micropolar fluids. Fluid motion is occurring along z*-axis and applied magnetic field is taken in the direction perpendicular to the direction of fluid motion. On applying appropriate boundary conditions, velocity profiles, microrotations, flow rate and shear stresses are obtained for the corresponding fluid regions. The graphs for volumetric flow rate and fluid velocity are plotted and discussed for different values of micropolar parameter, couple stress parameter, porosity, viscosity ratio parameter, Hartmann number, conductivity ratio parameters and Darcy numbers.MSC (2020): 76A05, 76S05, 76W05, 35Q35

scholarly journals Optimization of injected radiotracer volume for flow rate measurement in closed conduits

2020 ◽  
Vol 74 (5) ◽  
pp. 305-312
Author(s):  
Miroslav Pavlovic ◽  
Marijana Pantovic-Pavlovic ◽  
Pavel Bartl ◽  
Jasmina Stevanovic ◽  
Bojan Radak
Keyword(s):  
Flow Rate ◽  
Fluid Velocity ◽  
Plug Flow ◽  
Volumetric Flow Rate ◽  
Pilot Scale ◽  
Quality Performance ◽  
Flow Meters ◽  
Injection Volume ◽  
In Situ Calibration ◽  
Flow Quality

In chemical processes it is essential that the flow in the process is accurately defined. Fluid velocity measurements are important for fluid flow quality performance in flow systems. This study focuses on determination of the volumetric flow rate and its standard (relative) deviation for calibration of conventional flow meters by using a radiotracer approach. The measurements for flow meter calibration were performed at a pilot-scale flow rig using Technetium-99 m (99mTc) as a radiotracer in the form of pertechnetate ion (99mTcO4-). The measured data were analyzed, and precision of the experimental setup was investigated under two different approaches ? IAEA?s RTD software and sum approximation of raw data. For the first time, the variation of standard deviation of calculated flow rate with the injection volume and activity of the radiotracer was determined. Plug flow with axial dispersion was used to simulate the measured RTD curves and investigate the flow dynamics of the flowing water. The results of the study have shown the possibility of in situ calibration of flow meters with a relative error lower than 1 %. They also revealed a slight dependency of the precision of output results on the injection volume as well as similar results for manual and specialized RTD software data processing.

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