scholarly journals Role of natural convection in the dissolution of sessile droplets

2016 ◽  
Vol 794 ◽  
pp. 45-67 ◽  
Author(s):  
Erik Dietrich ◽  
Sander Wildeman ◽  
Claas Willem Visser ◽  
Kevin Hofhuis ◽  
E. Stefan Kooij ◽  
...  
Keyword(s):  
Pure Water ◽  
Convective Transport ◽  
Dissolution Time ◽  
Water Mixture ◽  
Scaling Relation ◽  
Equivalent Radius ◽  
Micro Particle Image Velocimetry ◽  
Convective Regime ◽  
Alcohol Water ◽  
Buoyancy Driven Convection

The dissolution process of small (initial (equivalent) radius $R_{0}<1$  mm) long-chain alcohol (of various types) sessile droplets in water is studied, disentangling diffusive and convective contributions. The latter can arise for high solubilities of the alcohol, as the density of the alcohol–water mixture is then considerably less than that of pure water, giving rise to buoyancy-driven convection. The convective flow around the droplets is measured, using micro-particle image velocimetry (${\rm\mu}$PIV) and the schlieren technique. When non-dimensionalizing the system, we find a universal $Sh\sim Ra^{1/4}$ scaling relation for all alcohols (of different solubilities) and all droplets in the convective regime. Here $Sh$ is the Sherwood number (dimensionless mass flux) and $Ra$ is the Rayleigh number (dimensionless density difference between clean and alcohol-saturated water). This scaling implies the scaling relation ${\it\tau}_{c}\propto R_{0}^{5/4}$ of the convective dissolution time ${\it\tau}_{c}$, which is found to agree with experimental data. We show that in the convective regime the plume Reynolds number (the dimensionless velocity) of the detaching alcohol-saturated plume follows $Re_{p}\sim Sc^{-1}Ra^{5/8}$, which is confirmed by the ${\rm\mu}$PIV data. Here, $Sc$ is the Schmidt number. The convective regime exists when $Ra>Ra_{t}$, where $Ra_{t}=12$ is the transition $Ra$ number as extracted from the data. For $Ra\leqslant Ra_{t}$ and smaller, convective transport is progressively overtaken by diffusion and the above scaling relations break down.

Experimental and Numerical Study of Methanol-Water Mixture Single-Phase Heat Transfer in a Micro-Channel Heat Sink

2012 ◽  
Author(s):  
Chun K. Kwok ◽  
Matthew M. Asada ◽  
Jonathan R. Mita ◽  
Weilin Qu
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Heat Sink ◽  
Single Phase ◽  
Numerical Study ◽  
Pure Water ◽  
Molar Fraction ◽  
Water Mixture ◽  
Micro Channel ◽  
Numerical Predictions

This paper presents an experimental study of single-phase heat transfer characteristics of binary methanol-water mixtures in a micro-channel heat sink containing an array of 22 microchannels with 240μm × 630μm cross-section. Pure water, pure methanol, and five methanol-water mixtures with methanol molar fraction of 16%, 36%, 50%, 63% and 82% were tested. Key parametric trends were identified and discussed. The experimental study was complemented by a three-dimensional numerical simulation. Numerical predictions and experimental data are in good agreement with a mean absolute error (MAE) of 0.87%.

CONDUCTANCES OF LITHIUM NITRATE SOLUTIONS IN ETHYL ALCOHOL AND ETHYL ALCOHOL - WATER MIXTURES AT 25.0 °C.

1956 ◽  
Vol 34 (9) ◽  
pp. 1232-1242 ◽  
Author(s):  
A. N. Campbell ◽  
G. H. Debus
Keyword(s):  
No Value ◽  
Ethyl Alcohol ◽  
Pure Water ◽  
Lithium Ion ◽  
Water Molecules ◽  
Lithium Nitrate ◽  
Absolute Alcohol ◽  
Pure Alcohol ◽  
Alcohol Water ◽  
Nitrate Solutions

The conductances of solutions of lithium nitrate in 30, 70, and 100 weight per cent ethyl alcohol have been determined at concentrations ranging from 0.01 molar up to saturation, at 25 °C. The densities and viscosities of these solutions have also been determined. The data have been compared with the calculated conductances obtained from the Wishaw–Stokes equation. The agreement is fairly good up to, say, 2 M, for all solvents except absolute alcohol. In the latter solvent there is no value of å, the distance of closest approach, which will give consistent values of the equivalent conductance. In passing from pure water to pure alcohol, the value of å increases progressively and this we attribute to a change in the solvation of the lithium ion from water molecules to alcohol molecules. Some further calculations incline us to the view that the nitrate ion, as well as the lithium ion, is solvated to some extent, at least in alcohol.

Characterization of Spray Formed by Diesel-Water Mixture Jet Injected Into an Air Crossflow

2017 ◽  
Author(s):  
Jinkwan Song ◽  
Jong Guen Lee
Keyword(s):  
Diesel Fuel ◽  
Drop Size ◽  
Pure Water ◽  
Fuel Mixture ◽  
Water Mixture ◽  
Fuel Injector ◽  
Spray Characteristics ◽  
Two Fluids ◽  
Mixing Ratios ◽  
Fuel Mixtures

Using a mixture of water and diesel fuel is considered a way to reduce gas emissions including NOx and COx in the gas turbine. This paper presents experimental results on spray characteristics of the water-diesel fuel mixture in an air crossflow. A plain-orifice type injector of 0.508 mm in diameter is employed in the research. Pure water, pure diesel fuel, and water-diesel fuel mixtures with different mixing ratios are used to compare their spray characteristics. In order to observe spray behaviors in different breakup regimes, Weber numbers for water of 30 and 125 are chosen as the operating condition and the corresponding Weber numbers for diesel fuel at the same conditions are 92 and 382, respectively. Momentum flux ratios are 10 and 20. A tee connection and a subsequent static mixer are employed at upstream of fuel injector to mix two liquids. Phase Doppler Particle Analyzer (PDPA) measurement is performed to measure droplet distributions and mean drop size at various mixture ratios, and planar laser induced fluorescence (PLIF) technique with dyeing either diesel or water is used to look into the primary breakup process. PDPA data show that the spray characteristics of water-diesel fuel mixtures such as mean drop size and number density distribution can be predicted from the measured drop size distribution of pure fluids by weighting those quantities by mass fraction of each fluid, indicating that the water and diesel are injected alternately without significant mixing between the two fluids. A short transition of liquid flow from water-to-diesel or diesel-to-water produces small fraction of relatively bigger droplets.

scholarly journals Lagrangian transport properties of pulmonary interfacial flows

2011 ◽  
Vol 705 ◽  
pp. 234-257 ◽  
Author(s):  
Bradford J. Smith ◽  
Sarah Lukens ◽  
Eiichiro Yamaguchi ◽  
Donald P. Gaver III
Keyword(s):  
Pulmonary Surfactant ◽  
Flow Characteristics ◽  
Fluid Phase ◽  
Convective Transport ◽  
Interfacial Flows ◽  
Lagrangian Analysis ◽  
Bulk Fluid ◽  
Free System ◽  
Micro Particle Image Velocimetry ◽  
Surfactant Transport

AbstractDisease states characterized by airway fluid occlusion and pulmonary surfactant insufficiency, such as respiratory distress syndrome, have a high mortality rate. Understanding the mechanics of airway reopening, particularly involving surfactant transport, may provide an avenue to increase patient survival via optimized mechanical ventilation waveforms. We model the occluded airway as a liquid-filled rigid tube with the fluid phase displaced by a finger of air that propagates with both mean and sinusoidal velocity components. Finite-time Lyapunov exponent (FTLE) fields are employed to analyse the convective transport characteristics, taking note of Lagrangian coherent structures (LCSs) and their effects on transport. The Lagrangian perspective of these techniques reveals flow characteristics that are not readily apparent by observing Eulerian measures. These analysis techniques are applied to surfactant-free velocity fields determined computationally, with the boundary element method, and measured experimentally with micro particle image velocimetry ($\ensuremath{\mu} $-PIV). We find that the LCS divides the fluid into two regimes, one advected upstream (into the thin residual film) and the other downstream ahead of the advancing bubble. At higher oscillatory frequencies particles originating immediately inside the LCS experience long residence times at the air–liquid interface, which may be conducive to surfactant transport. At high frequencies a well-mixed attractor region is identified; this volume of fluid cyclically travels along the interface and into the bulk fluid. The Lagrangian analysis is applied to velocity data measured with 0.01 mg ml−1 of the clinical pulmonary surfactant Infasurf in the bulk fluid, demonstrating flow field modifications with respect to the surfactant-free system that were not visible in the Eulerian frame.

scholarly journals Hydrophobic *BEA-Type Zeolite Membranes on Tubular Silica Supports for Alcohol/Water Separation by Pervaporation

Membranes ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 86 ◽  
Author(s):  
Kyohei Ueno ◽  
Saki Yamada ◽  
Toshinari Watanabe ◽  
Hideyuki Negishi ◽  
Takuya Okuno ◽  
...  
Keyword(s):  
Alternative Energy ◽  
Separation Performance ◽  
Water Mixture ◽  
Water Separation ◽  
Zeolite Membranes ◽  
Pure Silica ◽  
Large Pore ◽  
Silica Supports ◽  
Alcohol Water ◽  
Type Zeolite

Hydrophobic pure-silica *BEA-type zeolite membranes with large pores were prepared on tubular silica supports by hydrothermal synthesis using a secondary growth method and were applied to the separation of alcohol/water mixtures by pervaporation (PV), an alternative energy-efficient process for production of biofuels. Amorphous pure-silica tubular silica supports, free of Al atoms, were used for preparing the membranes. In this study, the effects of the synthesis conditions, such as the H2O/SiO2 and NH4F/SiO2 ratios in the synthetic gel, on the membrane formation process and separation performance were systematically investigated. The successfully prepared dense and continuous membranes exhibited alcohol selectivity and high flux for the separation of ethanol/water and butanol/water mixtures. The pure-silica *BEA membranes obtained under optimal conditions (0.08SiO2:0.5TEAOH:0.7NH4F:8H2O) showed high PV performance with a separation factor of 229 and a flux of 0.62 kg·m−2·h−1 for a 1 wt % n-butanol/water mixture at 318 K. This result was attributed to the hydrophobicity and large pore size of the pure-silica *BEA membrane. This was the first successful synthesis of hydrophobic large-pore zeolite membranes on tubular supports with alcohol selectivity, and the obtained results could provide new insights into the research on hydrophobic membranes with high permeability.

Temperature-dependency on adhesion force of ice made from surfactant–pure water mixture to copper surface

2017 ◽  
Vol 79 ◽  
pp. 39-48
Author(s):  
Koji Matsumoto ◽  
Kazuyuki Minamiya ◽  
Junki Sakamoto ◽  
Jun Ueda ◽  
Kohei Ehara ◽  
...  
Keyword(s):  
Adhesion Force ◽  
Pure Water ◽  
Copper Surface ◽  
Water Mixture ◽  
Temperature Dependency

scholarly journals Low-frequency Raman Spectroscopy of Aqueous Solutions of Aliphatic Alcohols

2001 ◽  
Vol 56 (8) ◽  
pp. 529-536 ◽  
Author(s):  
Koji Ydoshida ◽  
Toshio Yamaguchi
Keyword(s):  
Aqueous Solutions ◽  
Raman Spectra ◽  
Mole Fraction ◽  
Water Clusters ◽  
Pure Water ◽  
Low Frequency ◽  
Isosbestic Point ◽  
X Ray Diffraction ◽  
Alcohol Water ◽  
Solvent Clusters

Abstract Low-frequency Raman spectra have been measured at room temperature as functions of the alcohol mole fraction in aqueous solutions of methanol, ethanol, 1-propanol, 2 -propanol, and /er/-butylalcohol (TBA). Intrinsic Raman spectra R (ῡ) were obtained from depolarized Rayleigh wing spectra. Isosbestic points have been observed in R (ῡ) of the aqueous solutions of ethanol, 1-propanol, and 2 -propanol, suggesting that the structure o f the solutions is characterized by individual alcohol aggregates and water clusters without a significant amount of alcohol-water mixed aggregates. The R (ῡ) spectra have been expressed as R (ῡ ,x ) = w R (ῡ ,0 ) + aR(D, 1), where R(ῡ, 0) and R(ῡ, 1) are those for pure water and pure alcohols, respectively, and x is the mole fraction of alcohols. The coefficients w and a show the inflection points at characteristic alcohol mole fractions, where microhetrogeneity and structural transition of the solvent clusters take place, as previously shown by X-ray diffraction. In the aqueous solutions of methanol, where no microhetrogeneity takes place, no clear isosbestic point in R(ῡ) has been observed. For aqueous solutions of TBA, an isosbestic point in R(ῡ) has appeared when xTBA > 0.05. Two inflections points in the coefficients have been observed at xTBA « 0.1 and 0.35; the former composition corresponds to the transition composition from the TBA-TBA intermolecular contact to the TBA water molecular association, as previously reported by neutron diffraction.

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