Effect of flow rates of the continuous phase on droplet size in dripping and jetting regimes in a simple fluidic device for coaxial flow

2014 ◽  
Vol 454 ◽  
pp. 84-88 ◽  
Author(s):  
Seung-Kwan Moon ◽  
In Woo Cheong ◽  
Sung-Wook Choi
Keyword(s):  
Droplet Size ◽  
Continuous Phase ◽  
Flow Rates ◽  
Fluidic Device

scholarly journals Modeling of Droplet Generation in a Microfluidic Flow-Focusing Junction for Droplet Size Control

Micromachines ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 590
Author(s):  
Ali M. Ibrahim ◽  
Jose I. Padovani ◽  
Roger T. Howe ◽  
Yasser H. Anis
Keyword(s):  
Numerical Model ◽  
Droplet Size ◽  
Size Control ◽  
Continuous Phase ◽  
Immiscible Fluids ◽  
Droplet Generation ◽  
Flow Rate Ratio ◽  
Flow Focusing ◽  
Flow Rates ◽  
Microfluidic Flow

In this paper, we study the parameters that affect the generation of droplets in a microfluidic flow-focusing junction. Droplets are evaluated based on the size and frequency of generation. Droplet size control is essential for microfluidic lab-on-a-chip applications in biology, chemistry, and medicine. We developed a three-dimensional numerical model that can emulate the performance of the physical system. A numerical model can help design droplet-generation chips with new junction geometries, different dispersed and continuous phase types, and different flow rates. Our model uses a conservative level-set method (LSM) to track the interface between two immiscible fluids using a fixed mesh. Water was used for the dispersed phase and mineral oil for the continuous phase. The effects of the continuous-to-dispersed flow rate ratio (Qo/Qw) and the surfactant concentration on the droplet generation were studied both using the numerical model and experimentally. The numerical model was found to render results that are in good agreement with the experimental ones, which validates the LSM model. The validated numerical model was used to study the time effect of changing Qo/Qw on the generated droplet size. Properly timing when the flow rates are changed enables control over the size of the next generated droplet, which is useful for single-droplet size modulation applications.

Effect of Shear and Water Cut on Phase Inversion and Droplet Size Distribution in Oil–Water Flow

2018 ◽  
Vol 141 (3) ◽  
Author(s):  
Mo Zhang ◽  
Ramin Dabirian ◽  
Ram S. Mohan ◽  
Ovadia Shoham
Keyword(s):  
Size Distribution ◽  
Droplet Size ◽  
Phase Inversion ◽  
Droplet Size Distribution ◽  
Continuous Phase ◽  
Dispersed Phase ◽  
Water Emulsion ◽  
Inversion Region ◽  
Oil Water ◽  
Water Cut

Oil–water dispersed flow occurs commonly in the petroleum industry during the production and transportation of crudes. Phase inversion occurs when the dispersed phase grows into the continuous phase and the continuous phase becomes the dispersed phase caused by changes in the composition, interfacial properties, and other factors. Production equipment, such as pumps and chokes, generates shear in oil–water mixture flow, which has a strong effect on phase inversion phenomena. The objective of this paper is to investigate the effects of shear intensity and water cut (WC) on the phase inversion region and also the droplet size distribution. A state-of-the-art closed-loop two phase (oil–water) flow facility including a multipass gear pump and a differential dielectric sensor (DDS) is used to identify the phase inversion region. Also, the facility utilizes an in-line droplet size analyzer (a high speed camera), to record real-time videos of oil–water emulsion to determine the droplet size distribution. The experimental data for phase inversion confirm that as shear intensity increases, the phase inversion occurs at relatively higher dispersed phase fractions. Also the data show that oil-in-water emulsion requires larger dispersed phase volumetric fraction for phase inversion as compared with that of water-in-oil emulsion under the same shear intensity conditions. Experiments for droplet size distribution confirm that larger droplets are obtained for the water continuous phase, and increasing the dispersed phase volume fraction leads to the creation of larger droplets.

A Multifunctional Microfluidic Device Based on Bifurcation Geometry

2010 ◽  
Author(s):  
Ahmed Fadl ◽  
Stefanie Demming ◽  
Zongqin Zhang ◽  
Bjo¨rn Hoxhold ◽  
Stephanus Bu¨ttgenbach ◽  
...  
Keyword(s):  
Microfluidic Device ◽  
Microfluidic Devices ◽  
Optical Lithography ◽  
Working Fluid ◽  
The Novel ◽  
Flow Rates ◽  
Single Function ◽  
Fluidic Device ◽  
Bifurcation Structures ◽  
Novel Design

Developing multifunctional devices are essential to realize more efficient Microsystems. With miniaturization processes taking place in many different applications, the rooms for single function microfluidic devices are limited. In this study, we introduce a multifunctional micro fluidic device based on bifurcation geometry which is capable of performing pumping and mixing at the same time. Optical lithography is used to fabricate the designed microfluidic device. The microfluidic device is tested at low actuator frequencies, and ethanol is employed as a working fluid. The operational principles are based on rectifying the oscillatory flows by using bifurcation structures for flow rectification. The results prove the feasibility of the novel design, and results are presented in terms of flow rates and maximum back pressures.

scholarly journals DEVELOPMENT OF MICROEMULSION AND WATER/OIL/WATER MULTIPLE EMULSION CONTAINING BETA-ARBUTIN, LACTIC ACID, AND SODIUM ASCORBYL PHOSPHATE

2020 ◽  
pp. 212-220
Author(s):  
SILVIA SURINI ◽  
NUR MPN NEGORO
Keyword(s):  
Lactic Acid ◽  
Droplet Size ◽  
Physical Stability ◽  
Continuous Phase ◽  
Stability Studies ◽  
Flow Properties ◽  
Multiple Emulsion ◽  
Multiple Emulsions ◽  
Whitening Agent ◽  
Oil Water

Objective: In addition to lactic acid and sodium ascorbyl phosphate, which have whitening effects, beta-arbutin is a safe whitening agent for skin.Combining these three substances should reduce the concentration of each one in a formula and achieve an optimal whitening effect. In this study,microemulsions and water/oil/water (W/O/W) multiple emulsions were applied to produce a formula containing these whitening agents.Methods: All the active ingredients were formulated into microemulsions and W/O/W multiple emulsions with different concentrations of Tween 80and Span 80 as emulsifiers to obtain a stable formula. Twelve-week physical stability studies were performed for every formula at low (4±2°C), room(28±2°C), and high (40±2°C) temperatures.Results: The produced microemulsions were transparent with a mean droplet size of 15.50 nm. In addition, the W/O/W multiple emulsions containeddroplets within droplets, which were dispersed in a continuous phase with an inner droplet size of 0.15 μm and an outer droplet size of 0.37 μm. TheW/O/W multiple emulsions showed pseudoplastic thixotropic flow properties. Furthermore, the microemulsions were stable at low (4±2°C) androom (28±2°C) temperatures, while the W/O/W multiple emulsions were stable at room (28±2°C) and high (40±2°C) temperatures.Conclusion: It was concluded that the combination of beta-arbutin, lactic acid, and sodium ascorbyl phosphate was suitable for formulating intomicroemulsions as well as W/O/W multiple emulsions as whitening cosmetic products.

scholarly journals Water Droplets Translocation and Fission in a 3D Bi-Planar Multifurcated T-Junction Microchannels

Processes ◽  
2020 ◽  
Vol 8 (5) ◽  
pp. 510
Author(s):  
Inn-Leon Lu ◽  
Voon-Loong Wong ◽  
Jit-Kai Chin ◽  
Kuzilati Kushaari
Keyword(s):  
Droplet Size ◽  
Flow Behavior ◽  
Phase 1 ◽  
Maximum Velocity ◽  
Droplet Size Distribution ◽  
Continuous Phase ◽  
Fission Process ◽  
Model Studies ◽  
Daughter Droplets ◽  
Droplet Fission

Droplet fission has gained notable interest in drug delivery applications due to its ability to perform parallel operations in single device. Hitherto, droplet flow behavior in a 3D constriction was scarcely investigated. This study aims to investigate droplets fission inside a 3D bi-planar multifurcated microfluidic device. The flow behavior and droplet size distribution were studied in trifurcated microchannels using distilled water as dispersed phase (1 mPa·s) and olive oil (68 mPa·s) as continuous phase. Various sizes of subordinate daughter droplets were manipulated passively through the modulation of flowrate ratio (Q) (0.15 < Q < 3.33). Overall, we found droplet size coefficient of variations (CV%) ranging from 0.72% to 69%. Highly monodispersed droplets were formed at the upstream T-junction (CV% < 2%) while the droplet fission process was unstable at higher flowrate ratio (Q > 0.4) as they travel downstream (1.5% < CV% < 69%) to splitting junctions. Complex responses to the non-monotonic behavior of mean droplet size was found at the downstream boundaries, which arose from the deformations under nonuniform flow condition. CFD was used as a tool to study the preliminary maximum velocity (Umax) profile for the symmetrical (0.01334 m/s < Umax < 0.0153 m/s) and asymmetrical branched channels (0.0223 m/s< Umax < 0.00438 m/s), thus complementing the experimental model studies.

scholarly journals Highly concentrated emulsion with a cubic liquid crystal as the external phase: characterization and obtaining of meso/macroporous material

2013 ◽  
Vol 30 ◽  
pp. 87-96 ◽  
Author(s):  
E. Santamaría ◽  
M. Cortés ◽  
A. Maestro ◽  
M. Porras ◽  
J. M. Gutiérrez ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Droplet Size ◽  
Raw Materials ◽  
Water System ◽  
Chemical Society ◽  
Continuous Phase ◽  
Rheological Parameters ◽  
Macroporous Material ◽  
Internal Phase ◽  
External Phase

High internal phase ratio emulsions (HIPRE) or highly concentrated emulsions are characterized by their large internal phase volume.The nature and concentration of surfactant affects several features of the final emulsion, such as stability, droplet size and structure of the external phase. Therefore, an ordered external mesophase (structure of liquid crystal) can be obtained. The present work studies the influence of composition and preparation variables on the final properties of HIPRE with an external phase formed by a bicontinuous cubic liquid crystal. The studied outputs variables were droplet size, stability and rheological parameters as yield stress, viscosity at a fixed shear rate and the plateau value of the storage modulus. O/W HIPREs were prepared with a decane/brij 35/water system. Once the emulsions were characterized the meso/macroporous material was obtained. In order to prepare the materials, the emulsions were formed by incorporating the catalyst of the reaction (HCl) in the continuous phase. When the emulsions were formed, tetraethylorthosilicate (TEOS) was added as a silica source In order to optimize the production process a study of reutilization and recovery of some of the raw materials (i.e: the surfactant and the EtOH used) was done.DOI: http://dx.doi.org/10.3126/jncs.v30i0.9374Journal of Nepal Chemical Society Vol. 30, 2012 Page:  87-96 Uploaded date: 12/19/2013   

Effect of Drift Retardant Adjuvants on Spray Droplet Size of Water and Paraffinic Oil Applied at Ultralow Volume

1995 ◽  
Vol 9 (2) ◽  
pp. 380-384 ◽  
Author(s):  
James E Hanks
Keyword(s):  
Droplet Size ◽  
Liquid Flow ◽  
Water Soluble ◽  
Air Pressure ◽  
Spray Droplet ◽  
Flow Rates ◽  
Pressure Water ◽  
Paraffinic Oil

Adjuvants were evaluated to determine the effect on increasing spray droplet size and reducing the amount of spray dispensed in small driftable size particles when applying water and paraffinic oil at ultralow volume. Spray solutions were applied with an air-assist system at liquid flow rates of 28 and 56 ml/min and atomized with 14, 28, 42, 56, and 84 kPa of air pressure. Water and paraffinic oil were applied alone and with two drift retardant adjuvants mixed individually in each. The two water soluble adjuvants were mixed at concentrations of 0.25, 0.50, 0.75, 1.0, and 2.0%; oil soluble adjuvants were applied at 0.125, 0.25, and 0.50%. Adjuvants used in water and oil were effective at increasing droplet size and reducing the amount of liquid dispensed in small driftable size particles. Effectiveness of the adjuvants decreased as air pressures increased, with water soluble adjuvants being more susceptible to air pressure. Volume median diameters > 200 μm with water could be achieved without adjuvants; whereas with oil, an adjuvant was required.

CFD Study on must of Grapes Separation in a Hydrocyclone

2013 ◽  
Vol 837 ◽  
pp. 645-650
Author(s):  
Petru Cârlescu ◽  
Ioan Tenu ◽  
Marius Baetu ◽  
Radu Rosca
Keyword(s):  
Cfd Simulation ◽  
Reynolds Stress Model ◽  
Continuous Phase ◽  
Solid Particles ◽  
Advanced Degree ◽  
Separation And Purification ◽  
Discrete Phase Model ◽  
Flow Rates ◽  
Discrete Phase ◽  
Simulation And Experiment

Abstract. Hydrocyclones are increasingly used in the food industry for various separation and purification. In this paper, an optimization was made to design a hydrocyclone model using CFD (Computational Fluid Dynamics). CFD simulation is performed with FLUENT software by coupling the Reynolds Stress Model (RSM) for must of grapes flow with Discrete Phase Model (DPM) for solid particles trajectory. Coupling of discrete phase (particles) and continuous phase (must of grapes) in the mathematical model is set so that the continuous phase to influence discrete phase. Tracking particles traiectory in this hydrocyclone allows advanced degree is separation so obtained to the maximum particle size approaching the size of a yeast cell 10 μm, without separating them. Hydrocyclone dimensional designed simulation was performed and analyzed on an experimental pilot plant for three different must flow rates supply. Introduced particle flow rates simulation and experiment does not exceed 10% of the must flow rates. The degree of separation obtained is in agreement with experimental data.

scholarly journals The Effect of pH and High-Pressure Homogenization on Droplet Size

2017 ◽  
Vol 2 (4) ◽  
pp. 110-122
Author(s):  
Ah Pis Yong ◽  
Md. Aminul Islam ◽  
Nurul Hasan
Keyword(s):  
High Pressure ◽  
Light Scattering ◽  
Droplet Size ◽  
Skim Milk ◽  
Egg Yolk ◽  
Continuous Phase ◽  
High Pressure Homogenization ◽  
Emulsion Droplets ◽  
Droplet Sizes ◽  
Basil Oil

The aims of this study are to revisit the effect of high pressure on homogenization and the influence of pH on the emulsion droplet sizes. The high-pressure homogenization (HPH) involves two stages of processing, where the first stage involves in blending the coarse emulsion by a blender, and the second stage requires disruption of the coarse emulsion into smaller droplets by a high-pressure homogenizer. The pressure range in this review is in between 10-500 MPa. The homogenised droplet sizes can be reduced by increasing the homogenization recirculation, and there is a threshold point beyond that by applying pressure only, the size cannot be further reduced. Normally, homogenised emulsions are classified by their degree of kinetic stability. Dispersed phase present in the form of droplets while continuous phase also known as suspended droplets. With a proper homogenization recirculation and pressure, a more kinetically stable emulsion can be produced. The side effects of increasing homogenization pressure are that it can cause overprocessing of the emulsion droplets where the droplet sizes become larger rather than the expected smaller size. This can cause kinetic instability in the emulsion. The droplet size is usually measured by dynamic light scattering or by laser light scattering technique. The type of samples used in this reviews are such as chocolate and vanilla based powders; mean droplet sizes samples; basil oil; tomato; lupin protein; oil; skim milk, soymilk; coconut milk; tomato homogenate; corn; egg-yolk, rapeseed and sunflower; Poly(4-vinylpyridine)/silica; and Complex 1 until complex 4 approaches from author case study. A relationship is developed between emulsion size and pH. Results clearly show that lower pH offers smaller droplet of emulsion and the opposite occurs when the pH is increased.

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