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

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%.

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.

A Photographic Study on the Effects of Hydrophobic-Spot Size and Subcooling on Local Film Boiling

2013 ◽  
Author(s):  
Bambang Joko Suroto ◽  
Masahiro Tashiro ◽  
Sana Hirabayashi ◽  
Sumitomo Hidaka ◽  
Masamichi Kohno ◽  
...  
Keyword(s):  
Heat Flux ◽  
High Speed ◽  
Bubble Dynamics ◽  
Pure Water ◽  
Nucleate Boiling ◽  
Spot Size ◽  
Copper Surface ◽  
Film Boiling ◽  
Working Fluid ◽  
Boiling Regime

The effects of hydrophobic circle spot size and subcooling on local film boiling phenomenon from the copper surface with single PTFE (Polytetrafluoroethylene) hydrophobic circle spot at low heat flux has been investigated. The experiments were performed using pure water as the working fluid and subcooling ranging from 0 and 10K. The heat transfer surfaces are used polished copper block with single PTFE hydrophobic circle spot of diameters 2, 4 and 6 mm, respectively. A high-speed camera was used to capture bubble dynamics and disclosed the sequence of the process leading to local film boiling. The result shows that local films boiling occurs on the PTFE circle spot at low heat flux and was triggered by the merging of neighboring bubbles. The study also showed that transition time required for change from nucleate boiling regime to local film boiling regime depends on the diameter of the hydrophobic circle spot and the subcooling. A stable local film boiling occurs at the smallest diameter of hydrophobic spot. Subcooling cause the local film boiling occur at negative superheat and oscillation of bubble dome.

MOLECULAR DYNAMICS SIMULATION ON THE STRUCTURE AND DYNAMICS OF WATER IN THE 1-BUTYL-3-METHYLIMIDAZOLIUM TETRAFLUOROBORATE/WATER MIXTURE

2010 ◽  
Vol 09 (03) ◽  
pp. 573-584 ◽  
Author(s):  
GUOCAI TIAN ◽  
JIAN LI
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Pure Water ◽  
Molar Fraction ◽  
Blue Shift ◽  
Dynamics Simulation ◽  
Water Molecules ◽  
Water Mixture ◽  
Structure And Dynamics ◽  
Hydrogen Bond Interactions

The micro-structure, and IR spectrum of water molecules in 1-butyl-3-methylimi- dazolium tetrafluoroborate( [Bmim]BF4 )/water mixture with different concentrations (x1 = 25.0%, 50.0%, 75.0%, and 90.0%) were studied with molecular dynamics simulation at room temperature. It was shown that water molecules tend to be isolated from each other in mixtures with more ions than water molecules in pure water. With the increase of the molar fraction of water in the mixture, the rotation bands and the bending bands of water display red shift from 566.2 to 651.4 cm-1 and from 1638.4 to 1683.2 cm-1 respectively, whereas the O–H stretch bands show blue shift from 3519.8 to 3452 cm-1, which agree well with the experimental results. This suggests that the molecules are hindered and their motions are difficult and slow, due to the hydrogen-bond interactions and the inharmonic interactions between the inter- or intra-molecular modes of water molecules.

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.

scholarly journals Functionalized Graphene Oxide Modified Polyethersulfone Membranes for Low-Pressure Anionic Dye/Salt Fractionation

Polymers ◽  
2018 ◽  
Vol 10 (7) ◽  
pp. 795 ◽  
Author(s):  
Lifen Liu ◽  
Xin Xie ◽  
Rahul Zambare ◽  
Antony Selvaraj ◽  
Bhuvana Sowrirajalu ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Pore Size ◽  
Adhesion Force ◽  
Pure Water ◽  
Dye Adsorption ◽  
Alkaline Condition ◽  
Operating Pressure ◽  
Functionalized Graphene ◽  
Dye Molecules ◽  
Functionalized Graphene Oxide

In this study, polyelectrolyte assembled functionalized graphene oxide (PE-GO) membranes were fabricated through a one-step charge facilitated deposition method for high performance dye/salt separation. According to the intercalation of polydopamine (PDA) and (ionic liquid) IL functional moieties into the GO membranes, the pore size of the resulted PE-pGO and PE-iGO membrane increased from 2.69 nm to 4.13 nm and 6.54 nm, respectively. Correspondingly, a pure water flux of 13.8 ± 2.2, 36.7 ± 3.4, and 52.1 ± 6.7 L m−1 h−1 bar−1 was achieved for PE-GO, PE-pGO and PE-iGO membrane, respectively. PE-iGO membrane with the largest pore size could be operated with significant water permeability (28.3 to 38.3 L m−1 h−1 bar−1) at a low operating pressure range of 0.5–2 bar (dye concentration = 100 ppm, salt concentration = 5 g/L). More importantly, functionalities introduced to the GO nanosheets are found to impact the dye adsorption to the membrane surface. The IL intercalation promotes the elution of dye molecules from the IL moieties at elevated pH, therefore enhancing the efficiency of alkaline washing of the membrane. By contrast, the intercalation of PDA weakens such efficiency due to its strong adhesion force to the dye molecules even at the alkaline condition.

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