scholarly journals Experimental Study of Bubble Formation from a Micro-Tube in Non-Newtonian Fluid

Micromachines ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 71
Author(s):  
Georgia Kontaxi ◽  
Yorgos G. Stergiou ◽  
Aikaterini A. Mouza
Keyword(s):  
Liquid Phase ◽  
Shear Rate ◽  
Newtonian Fluid ◽  
Gas Flow ◽  
Bubble Formation ◽  
Release Time ◽  
Internal Diameter ◽  
Asymptotic Value ◽  
Shear Thinning Fluids ◽  
A Value

Over the last few years, microbubbles have found application in biomedicine. In this study, the characteristics of bubbles formed when air is introduced from a micro-tube (internal diameter 110 μm) in non-Newtonian shear thinning fluids are studied. The dependence of the release time and the size of the bubbles on the gas phase rate and liquid phase properties is investigated. The geometrical characteristics of the bubbles are also compared with those formed in Newtonian fluids with similar physical properties. It was found that the final diameter of the bubbles increases by increasing the gas flow rate and the liquid phase viscosity. It was observed that the bubbles formed in a non-Newtonian fluid have practically the same characteristics as those formed in a Newtonian fluid, whose viscosity equals the asymptotic viscosity of the non-Newtonian fluid, leading to the assumption that the shear rate around an under-formation bubble is high, and the viscosity tends to its asymptotic value. To verify this notion, bubble formation was simulated using Computational Fluid Dynamics (CFD). The simulation results revealed that around an under-formation bubble, the shear rate attains a value high enough to lead the viscosity of the non-Newtonian fluid to its asymptotic value.

scholarly journals Concentric cylinder viscometer flows of Herschel-Bulkley fluids

2019 ◽  
Vol 29 (1) ◽  
pp. 173-181 ◽  
Author(s):  
Hans Joakim Skadsem ◽  
Arild Saasen
Keyword(s):  
Shear Rate ◽  
Yield Stress ◽  
Couette Flow ◽  
Newtonian Fluid ◽  
Shear Thinning ◽  
Newtonian Fluids ◽  
Drilling Fluids ◽  
Concentric Cylinder ◽  
Shear Thinning Fluids ◽  
Cylinder Viscometer

Abstract Drilling fluids and well cements are example non-Newtonian fluids that are used for geothermal and petroleum well construction. Measurement of the non-Newtonian fluid viscosities are normally performed using a concentric cylinder Couette geometry, where one of the cylinders rotates at a controlled speed or under a controlled torque. In this paper we address Couette flow of yield stress shear thinning fluids in concentric cylinder geometries.We focus on typical oilfield viscometers and discuss effects of yield stress and shear thinning on fluid yielding at low viscometer rotational speeds and errors caused by the Newtonian shear rate assumption. We relate these errors to possible implications for typical wellbore flows.

FORMATION OF NANOLITER BUBBLES IN MICROFLUIDIC T-JUNCTIONS

NANO ◽  
2010 ◽  
Vol 05 (03) ◽  
pp. 175-184 ◽  
Author(s):  
JING FAN ◽  
YUXIANG ZHANG ◽  
LIQIU WANG
Keyword(s):  
Liquid Phase ◽  
Flow Rate ◽  
Formation Process ◽  
Relative Velocity ◽  
Gas Flow ◽  
Numerical Study ◽  
Bubble Formation ◽  
Pressure Variation ◽  
Width Ratio ◽  
Gas Flow Rate

A numerical study on nanoliter bubble formation process in microfluidic T-junctions is conducted. The simulated bubble sequence agrees well with experiments. The pressure and velocity distribution in liquid phase, and streamlines of relative velocity of liquid to bubbles are obtained. We also studied pressure variation at the junction and gas flow rate for the first several bubbles, and illustrated the special impact of channel width ratio on bubble formation process. Finally, we derived the critical nondimensional gas pressure above which bubbles can be generated.

scholarly journals Quantification of shear viscosity and wall slip velocity of highly concentrated suspensions with non-Newtonian matrices in pressure driven flows

2021 ◽  
Author(s):  
Patrick Wilms ◽  
Jan Wieringa ◽  
Theo Blijdenstein ◽  
Kees van Malssen ◽  
Reinhard Kohlus
Keyword(s):  
Shear Stress ◽  
Liquid Phase ◽  
Shear Rate ◽  
Shear Viscosity ◽  
Slip Velocity ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Wall Slip ◽  
Flow Index ◽  
Concentrated Suspensions

AbstractThe rheological characterization of concentrated suspensions is complicated by the heterogeneous nature of their flow. In this contribution, the shear viscosity and wall slip velocity are quantified for highly concentrated suspensions (solid volume fractions of 0.55–0.60, D4,3 ~ 5 µm). The shear viscosity was determined using a high-pressure capillary rheometer equipped with a 3D-printed die that has a grooved surface of the internal flow channel. The wall slip velocity was then calculated from the difference between the apparent shear rates through a rough and smooth die, at identical wall shear stress. The influence of liquid phase rheology on the wall slip velocity was investigated by using different thickeners, resulting in different degrees of shear rate dependency, i.e. the flow indices varied between 0.20 and 1.00. The wall slip velocity scaled with the flow index of the liquid phase at a solid volume fraction of 0.60 and showed increasingly large deviations with decreasing solid volume fraction. It is hypothesized that these deviations are related to shear-induced migration of solids and macromolecules due to the large shear stress and shear rate gradients.

scholarly journals Effect of Surfactants on Gas Holdup in Shear-Thinning Fluids

2017 ◽  
Vol 2017 ◽  
pp. 1-7 ◽  
Author(s):  
Shaobai Li ◽  
Siyuan Huang ◽  
Jungeng Fan
Keyword(s):  
Experimental Data ◽  
Liquid Phase ◽  
Sodium Dodecyl ◽  
Shear Thinning ◽  
Gas Holdup ◽  
Bubble Columns ◽  
Gas Velocity ◽  
Shear Thinning Fluids ◽  
Liquid Surface Tension ◽  
Superficial Gas Velocity

In this study, the gas holdup of bubble swarms in shear-thinning fluids was experimentally studied at superficial gas velocities ranging from 0.001 to 0.02 m·s−1. Carboxylmethyl cellulose (CMC) solutions of 0.2 wt%, 0.6 wt%, and 1.0 wt% with sodium dodecyl sulfate (SDS) as the surfactant were used as the power-law (liquid phase), and nitrogen was used as the gas phase. Effects of SDS concentration, rheological behavior, and physical properties of the liquid phase and superficial gas velocity on gas holdup were investigated. Results indicated that gas holdup increases with increasing superficial gas velocity and decreasing CMC concentration. Moreover, the addition of SDS in CMC solutions increased gas holdup, and the degree increased with the surfactant concentration. An empirical correlation was proposed for evaluating gas holdup as a function of liquid surface tension, density, effective viscosity, rheological property, superficial gas velocity, and geometric characteristics of bubble columns using the experimental data obtained for the different superficial gas velocities and CMC solution concentrations with different surfactant solutions. These proposed correlations reasonably fitted the experimental data obtained for gas holdup in this system.

scholarly journals EVALUASI KINERJA METHYL DIETHANOL AMINE (MDEA) DALAM PENYERAPAN KANDUNGAN H2S PADA PROSES PENGOLAHAN GAS ALAM

EKOLOGIA ◽  
2020 ◽  
Vol 20 (1) ◽  
pp. 45-51
Author(s):  
. Sutanto ◽  
Ade Heri Mulyati ◽  
. Hermanto
Keyword(s):  
Natural Gas ◽  
Flow Rate ◽  
Gas Flow ◽  
Acid Gas ◽  
Amine Solution ◽  
A Value ◽  
Logarithmic Equation ◽  
Counter Current ◽  
Column Outlet ◽  
Sour Gas

Drilling natural gas contains water vapor (H2O) and contaminant gases such as CO2 and H2S which must be removed because it reduced the calorie value of the product. H2S gas is also corrosive, easily damaging equipment so that it increased maintenance costs. The process of removing CO2 and H2S gas uses MDEA (methyl diethanolamine). This study aims to determine the optimal concentration and flow rate of absorbent methyl diethanolamine (MDEA) to absorb H2S in the plant I gas flow in Energy Equity Epic (Sengkang) Pty.Ltd. The study was carried out with a steady MDEA mix absorbent flow rate (50% pure amine and 50% demineralization water) fixed at 13 US Gallons per minute flowing continuously at the upper absorber inlet, sour gas flow rate, at the bottom of the absorber inlet with variations in the flow gas namely 7,9,11,13,15,17 MMSCFD and is contacted with amine solution counter-current. Purified natural gas (sweet gas) produced from the top absorber column outlet with an H2S content below 10 ppm. The results showed that the greater the flow rate of gas inlet, the greater the acid gas absorbed. The  amount  of gas  entering and  exiting gas follows the  equation        y = 0.003 x - 2.2537. The ability of the amine solution to absorb H2S follows the logarithmic equation y = 0.167 ln (x) + 101.02 with a value of R = 0.9857, y is H2S absorbed by the amine solution and x is the H2S rate.

Carbon Capture From Natural Gas via Polymeric Membranes

2018 ◽  
pp. 3043-3055
Author(s):  
Nayef Mohamed Ghasem ◽  
Nihmiya Abdul Rahim ◽  
Mohamed Al-Marzouqi
Keyword(s):  
Liquid Phase ◽  
Low Temperature ◽  
Gas Flow ◽  
Polymeric Membrane ◽  
Co2 Absorption ◽  
Membrane Contactor ◽  
Liquid Temperature ◽  
Liquid Phase Boundary ◽  
Key Factor ◽  
Absorption Performance

Polymeric membrane is a promising energy effective and an active alternative for conventional CO2 absorption column. The type of absorption liquid and operating parameters plays an efficient role in the ultimate absorption/stripping performance using gas-liquid membrane contactor. The gas flow rate has a significant effect on CO2 absorption performance, by contrast, it has no effect on stripping performance. Further the CO2 absorption performance in membrane contactor could be enhanced by high liquid flow rates. Because the gas–liquid contact time was a key factor to enhance the stripping flux at low temperature while liquid phase boundary layer thickness and associated mass transfer resistance is important at elevated temperature. So by controlling the liquid phase velocity and the length of module at low temperature better stripping performance can be achieved. The effect of liquid temperature on absorption performance in gas-liquid is not straightforward, since the liquid temperature cooperatively influence several factors.

Dynamics of bubble formation at micro-orifices under constant gas flow conditions

2020 ◽  
Vol 132 ◽  
pp. 103407
Author(s):  
Ehsan Mohseni ◽  
Jaunty Jose Kalayathine ◽  
Sebastian Felix Reinecke ◽  
Uwe Hampel
Keyword(s):  
Gas Flow ◽  
Bubble Formation ◽  
Flow Conditions

Numerical Simulation of Bubble Formation in Co-Flowing Mercury

2008 ◽  
Author(s):  
Ashraf Ibrahim ◽  
Mark Wendel ◽  
David Felde ◽  
Bernard Riemer
Keyword(s):  
Acoustic Waves ◽  
Bubble Growth ◽  
Gas Flow ◽  
Bubble Formation ◽  
Science Center ◽  
Proton Radiography ◽  
Two Phase ◽  
Vof Model ◽  
Computational Fluid Dynamics Cfd ◽  
Bubble Sizes

In this work, we present computational fluid dynamics (CFD) simulations of helium bubble formation and detachment at a submerged needle in stagnant and co-flowing mercury. Since mercury is opaque, visualization of internal gas bubbles was done with proton radiography (pRad) at the Los Alamos Neutron Science Center (LANSCE2). The acoustic waves emitted at the time of detachment and during subsequent oscillations of the bubble were recorded with a microphone. The Volume of Fluid (VOF) model was used to simulate the unsteady two-phase flow of gas injection in mercury. The VOF model is validated by comparing detailed bubble sizes and shapes at various stages of the bubble growth and detachment, with the experimental measurements at 1.66 mg/min helium gas flow rate and different mercury velocities. The experimental and computational results show a two-stage bubble formation in stagnant mercury. The first stage involves growing bubble around the needle, and the second follows as the buoyancy overcomes wall adhesion. The comparison of predicted and measured bubble sizes and shapes at various stages of the bubble growth and detachment is in good agreement.

The thinning of lamellae in surfactant-free foams with non-Newtonian liquid phase

2008 ◽  
Vol 616 ◽  
pp. 235-262 ◽  
Author(s):  
L. N. BRUSH ◽  
S. M. ROPER
Keyword(s):  
Liquid Phase ◽  
Shear Rate ◽  
Transition Region ◽  
Power Law ◽  
Capillary Number ◽  
Newtonian Liquid ◽  
Liquid Viscosity ◽  
Plateau Border ◽  
Shear Rates ◽  
Border Regions

Thinning rates of liquid lamellae in surfactant-free non-Newtonian gas–liquid foams, appropriate for ceramic or polymer melts and also in metals near the melting point, are derived in two dimensions by matched asymptotic analysis valid at small capillary number. The liquid viscosity is modelled (i) as a power-law function of the shear rate and (ii) by the Ellis law. Equations governing gas–liquid interface dynamics and variations in liquid viscosity are derived within the lamellar, transition and plateau border regions of a corner of the liquid surrounding a gas bubble. The results show that the viscosity varies primarily in the very short transition region lying between the lamellar and the Plateau border regions where the shear rates can become very large. In contrast to a foam with Newtonian liquid, the matching condition which determines the rate of lamellar thinning is non-local. In all cases considered, calculated lamellar thinning rates exhibit an initial transient thinning regime, followed by a t−2 power-law thinning regime, similar to the behaviour seen in foams with Newtonian liquid phase. In semi-arid foam, in which the liquid fraction is O(1) in the small capillary number, results explicitly show that for both the power-law and Ellis-law model of viscosity, the thinning of lamella in non-Newtonian and Newtonian foams is governed by the same equation, from which scaling laws can be deduced. This result is consistent with recently published experimental results on forced foam drainage. However, in an arid foam, which has much smaller volume fraction of liquid resulting in an increase in the Plateau border radius of curvature as lamellar thinning progresses, the scaling law depends on the material and the thinning rate is not independent of the liquid viscosity model parameters. Calculations of thinning rates, viscosities, pressures, interface shapes and shear rates in the transition region are presented using data for real liquids from the literature. Although for shear-thinning fluids the power-law viscosity becomes infinite at the boundaries of the internal transition region where the shear rate is zero, the interface shape, the pressure and the internal shear rates calculated by both rheological models are indistinguishable.

Effect of Nanoparticles on the Spreading of Bubble Triple Line on Top of a Stainless Steel Substrate Nozzle

2010 ◽  
Author(s):  
Saeid Vafaei ◽  
Dongsheng Wen
Keyword(s):  
Stainless Steel ◽  
Gas Flow ◽  
Stainless Steel Substrate ◽  
Liquid Droplet ◽  
Steel Substrate ◽  
Bubble Formation ◽  
Triple Line ◽  
Characteristic Points ◽  
Substrate Plate ◽  
Good Agreement

The purpose of this study is to investigate the effect of gold nanofluid on the formation of gas bubbles on top of a stainless steel substrate plate nozzle. The experiment reveals a unique phenomenon of enhanced pinning of the triple line of gold nanofluids for bubbles forming on the substrate plate, i.e the gold nanoparticles are found to prevent the spreading of the triple line during the bubble formation. Different to the liquid droplet measurement, the bubble contact angle is found to be slightly larger for formation of bubbles inside gold nanofluids. It is also observed that bubbles develop earlier inside the nanofluids with reduced bubble departure volume and increased bubble formation frequency. The shape of the bubble is found to be in good agreement with predictions of the Laplace-Young equation under the low gas flow rates inside water. Such a good agreement is also observed for bubbles forming inside nanofluids except a few characteristic points. The variation of solid surface tensions and the resultant force balances at the triple line are believed to be responsible for the modified dynamics of the triple line inside gold nanofluids and subsequent bubble formation.

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