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

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.

Download Full-text

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

Journal of Energy Resources Technology ◽

10.1115/1.4041661 ◽

2018 ◽

Vol 141 (3) ◽

Cited By ~ 1

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.

Download Full-text

Influence of Semicontinuous Processing on the Rheology and Droplet Size Distribution of Mayonnaise-like Emulsions

Food Science and Technology International ◽

10.1177/1082013209345046 ◽

2009 ◽

Vol 15 (4) ◽

pp. 367-373 ◽

Cited By ~ 7

Author(s):

C. Bengoechea ◽

M.L. López ◽

F. Cordobés ◽

A. Guerrero

Keyword(s):

Size Distribution ◽

Droplet Size ◽

Flow Rate ◽

Droplet Size Distribution ◽

Egg Yolk ◽

Continuous Phase ◽

Agitation Speed ◽

Viscosity Data ◽

Pumping System ◽

Oil In Water

Oil-in-water (o/w) emulsions stabilized by egg yolk, with a composition similar to those found in commercial mayonnaises or salad dressings, were processed in a semicontinuous device. This specially designed emulsification device consists of, basically, a vessel provided with an anchor impeller, where the continuous phase was initially placed; a pumping system that controls the addition of the oily phase; a rotor-stator unit, where the major breaking of the oily droplets takes place, and a recirculation system. The design allowed the introduction of a rotational rheometer to obtain viscosity data along the emulsification process. The most important advantages of this in-line emulsification device, when compared to discontinuous emulsification equipment, are the possibilities of recording viscosity data along the process and the higher values for the storage, G', and loss moduli, G'', of the resulting emulsions. The influence of egg yolk concentration, agitation speed, and flow rate over the rheological properties (G', G'') as well as droplet size distribution were investigated. Higher protein concentration, agitation speed and flow rate generally produce emulsions with higher G' and G'' values.

Download Full-text

OPERATIONAL CONSIDERATIONS FOR OPTIMUM DEPOSITION EFFICIENCY IN AERIAL APPLICATION OF DISPERSANTS

International Oil Spill Conference Proceedings ◽

10.7901/2169-3358-1983-1-53 ◽

1983 ◽

Vol 1983 (1) ◽

pp. 53-60 ◽

Cited By ~ 1

Author(s):

Gordon P. Lindblom ◽

Bryan S. Cashion

Keyword(s):

Droplet Size ◽

Oil Spills ◽

Droplet Size Distribution ◽

Deposition Efficiency ◽

Field Trials ◽

Aviation Industry ◽

Agricultural Practice ◽

Aerial Application ◽

Model Studies ◽

Spray System

ABSTRACT The growing worldwide recognition of the value of aircraft for application of dispersants to marine oil spills has resulted in a number of tests and field trials, but they have developed new concerns regarding control of depositional efficiency. These are similar to those extensively studied by the agricultural aviation industry, and involve anything influencing placement of a calculated dosage on a given area with minimum variation or loss due to aircraft turbulence, drift, or other factors. Aerial application of dispersants differs from agricultural practice in the physical properties of the fluids sprayed, the dosage generally required, and operational factors such as altitude, speed, swath, and total area to be covered. Consideration of these may result in need for special mechanical designs or alterations in the spray system. The major requirement for depositional efficiency is the droplet size distribution, which is affected by at least five factors. The most critical are nozzle diameter, viscosity of the fluid sprayed, and its exit velocity relative to the aircraft speed. These, together with pressure and pump rates, result in two shear regimes which are the ultimate controllers of droplet size. This report presents evidence for the above from mathematical model studies, laboratory windstream tests, and flight tests of both piston and turbo-powered aircraft. The data are used to propose a framework of requirements for optimal aerial dispersant application operations.

Download Full-text

Modeling Maximum Droplet Size In Gas-Liquid Annular Flow and Liquid–Liquid Dispersed Flow

10.2118/206081-ms ◽

2021 ◽

Author(s):

Kanat Karatayev ◽

Yilin Fan

Keyword(s):

Experimental Data ◽

Open Source ◽

Droplet Size ◽

Annular Flow ◽

Flow Behavior ◽

Droplet Size Distribution ◽

Theoretical Models ◽

Dispersed Phase ◽

Complex Flow ◽

Dispersed Flow

Abstract Hydrocarbon production is commonly associated as the dispersed flow of two and more immiscible phases starting from porous media to surface facilities. In the dispersed flow, one phase is usually dispersed into another dominating phase in terms of droplets. Accurate prediction of the droplet size distribution of a dispersed phase is critical in characterizing complex flow behavior in pipe flows. In the first part of this paper, we provide the analyses of open-source experimental data on the maximum droplet size in gas-liquid annular flow and evaluate the existing theoretical models and suggest an improvement based on the experimental data analyses to predict the maximum droplet size of the entrained liquid droplets in gas-liquid annular flow. In the second part of this paper, we cover the experimental results from the open-source literature data and in-house experimental data to give the general understanding on droplet formation concepts and evaluate the existing predictive models and present a new modeling approach to determine a maximum stable droplet size of the dispersed phase in the liquid-liquid dispersed flow under turbulent flow conditions.

Download Full-text

Characterization of water-in-oil emulsions produced with microporous hollow polypropylene fibers

Journal of the Serbian Chemical Society ◽

10.2298/jsc0011829v ◽

2000 ◽

Vol 65 (11) ◽

pp. 829-837

Author(s):

Goran Vladisavljevic ◽

Sabine Brösel ◽

Helmar Schubert

Keyword(s):

Size Distribution ◽

Disperse Phase ◽

Droplet Size ◽

Pressure Difference ◽

Droplet Diameter ◽

Droplet Size Distribution ◽

Continuous Phase ◽

Transmembrane Pressure ◽

Polypropylene Fibers ◽

Oil Emulsions

The preparation of fine and monodispersed water-in-oil (W/O) emulsions by utilizing hydrophobic hollow polypropylene fibers with 0.4 mm pores was investigated in this work. The experiments were carried out using demineralized water as the disperse phase, mineral oil Velocite No. 3 as the continuous phase, and polyglycerol polyricinoleate (PGPR 90) in the concentration range of 2.5 - 10 wt % as the oil-soluble emulsifier. The size of the water droplets in the prepared emulsions and the droplet size distribution strongly depend on the content of the disperse phase, the transmembrane pressure difference, and the emulsifier concentration. Stable emulsions with a very narrow droplet size distribution and a mean droplet diameter lower than 0.27 ?m were produced using 10 wt % PGPR 90 at a pressure difference below 30 kPa.

Download Full-text

PREDICTION OF OIL DROPLET MOVEMENT AND SIZE DISTRIBUTION: LAGRANGIAN METHOD AND VDROP-J MODEL

International Oil Spill Conference Proceedings ◽

10.7901/2169-3358-2017.1.1194 ◽

2017 ◽

Vol 2017 (1) ◽

pp. 1194-1211 ◽

Cited By ~ 4

Author(s):

Feng Gao ◽

Lin Zhao ◽

Frank Shaffer ◽

Roozbeh Golshan ◽

Michel Boufadel ◽

...

Keyword(s):

Size Distribution ◽

Droplet Size ◽

Droplet Size Distribution ◽

Added Mass ◽

Visual Observation ◽

Mass Force ◽

Lagrangian Particle ◽

Horizontal Pipe ◽

Droplet Movement ◽

Daughter Droplets

ABSTRACT (2017-306): During subsurface oil releases, oil disperses into droplets whose trajectories depend on the droplet size. We report the measurements of the droplet size distribution (DSD) obtained from the release of diesel at 135 GPM from a horizontal pipe in the Ohmsett tank. The DSD was predicted using the model VDROP-J and matched the observation. Subsequently, the movement of the droplets was tracked using a Lagrangian Particle Tracking (LPT) approach. Various forces affecting the migration of the droplets were considered, these include drag, buoyancy, lift, and added mass force. It was found that the lift force is negligible. The added mass force was negligible for droplets smaller than 500 μm. Visual observation and modeling indicated that large droplets (larger than 300 μm) tend to separate from the plume and migrate upward independently, which affects, not only the DSD of large droplets but also the resulting daughter droplets. This is an issue that has not been addressed in the literature. Our findings indicate that the DSD is needed to better predict the trajectory of oil blowouts.

Download Full-text

Modulation of spray droplet number density and size distribution by an acoustic field

The Journal of Computational Multiphase Flows ◽

10.1177/1757482x17690751 ◽

2017 ◽

Vol 9 (1) ◽

pp. 32-46 ◽

Cited By ~ 2

Author(s):

Javier Achury ◽

Wolfgang Polifke

Keyword(s):

Size Distribution ◽

Droplet Size ◽

Acoustic Field ◽

Density Wave ◽

Droplet Size Distribution ◽

Continuous Phase ◽

Number Density ◽

Size Dependent ◽

Preferential Concentration ◽

Momentum Coupling

Multiple interactions may occur when a poly-disperse spray is exposed to an acoustic field. In the context of spray combustion instabilities, acoustic agglomeration, the formation of a droplet number density wave and the modulation of the droplet size distribution are interesting effects. A droplet number density wave, i.e. preferential concentration of droplets in space, may result from size-dependent, one-way momentum coupling between the acoustic field and the spray. The modulation of the droplet size distribution, which has been evidenced in the experimental work of Gurubaran and Sujith (AIAA 2008-1046), is thus a consequence of the droplet number density wave formation. In the present work, the mechanisms that produce these effects are simulated and analyzed in depth by means of computational fluid dynamics. The spray is modeled with both Lagrangian (particles mass-point approach) and Eulerian (continuous phase approach) descriptions. The particular Eulerian method used is a variant of the presumed density function method of moments, which allows to account for the effects of poly-dispersity, in particular the size-dependence of particle velocity. Both the Lagrangian and Eulerian models are validated against experimental data for spray dynamics and spray response to an acoustic field.

Download Full-text