Critical droplet volume for spontaneous capillary wrapping

2010 ◽  
Vol 97 (12) ◽  
pp. 124103 ◽  
Author(s):  
Longquan Chen ◽  
Xiang Wang ◽  
Weijia Wen ◽  
Zhigang Li
Keyword(s):  
Droplet Volume ◽  
Critical Droplet

WATER DROPLET EVAPORATION IN A CHAMBER ISOLATED FROM THE EXTERNAL ENVIRONMENT

2020 ◽  
Vol 6 (3) ◽  
pp. 8-22
Author(s):  
KSENIA A. Batishcheva ◽  
ATLANT E. Nurpeiis
Keyword(s):  
Water Vapor ◽  
Evaporation Rate ◽  
External Environment ◽  
Heat Removal ◽  
Droplet Evaporation ◽  
Droplet Volume ◽  
Evaporation Time ◽  
Aluminum Alloy Amg6 ◽  
Evaporation Of Droplets ◽  
Contact Diameter

With an increase in the productivity of power equipment and the miniaturization of its components, the use of traditional thermal management systems becomes insufficient. There is a need to develop drip heat removal systems, based on phase transition effects. Cooling with small volumes of liquids is a promising technology for microfluidic devices or evaporation chambers, which are self-regulating systems isolated from the external environment. However, the heat removal during evaporation of droplets into a limited volume is a difficult task due to the temperature difference in the cooling device and the concentration of water vapor that is unsteady in time depending on the mass of the evaporated liquid. This paper presents the results of an experimental study of the distilled water microdrops’ (5-25 μl) evaporation on an aluminum alloy AMg6 with the temperatures of 298-353 K in an isolated chamber (70 × 70 × 30 mm3) in the presence of heat supply to its lower part. Based on the analysis of shadow images, the changes in the geometric dimensions of evaporating drops were established. They included the increase in the contact diameter, engagement of the contact line due to nano roughening and chemical composition inhomogeneous on the surface (90-95% of the total evaporation time) of the alloy and a decrease in the contact diameter. The surface temperature and droplet volume did not affect the sequence of changes in the geometric dimensions of the droplets. It was found that the droplet volume has a significant effect on the evaporation time at relatively low substrate temperatures. The results of the analysis of droplet evaporation rates and hygrometer readings have shown that reservoirs with salt solutions can be used in isolated chambers to control the concentration of water vapor. The water droplets evaporation time was determined. The analysis of the time dependences of the evaporation rate has revealed that upon the evaporation of droplets in an isolated chamber under the conditions of the present experiment, the air was not saturated with water vapor. The latter did not affect the evaporation rate.

scholarly journals Contribution of droplet volume fluctuation to dispersion of nanowire length

2016 ◽  
Vol 741 ◽  
pp. 012040
Author(s):  
Y Berdnikov ◽  
N V Sibirev ◽  
V G Dubrovskii
Keyword(s):  
Droplet Volume

scholarly journals Planar droplet sizing: Application to a spray of Jet A1 kerosene

2017 ◽  
Author(s):  
Pierre Doublet ◽  
Christine Lempereur ◽  
Virginel Bodoc ◽  
Mikael Orain ◽  
Pierre Gajan
Keyword(s):  
Light Intensity ◽  
Scattered Light ◽  
Droplet Surface ◽  
Scattered Light Intensity ◽  
Field Of View ◽  
Fluorescence Signal ◽  
Droplet Volume ◽  
Image Processing Algorithm ◽  
Two Phase ◽  
Scattering Angle

Optical techniques are  widely employed for their non-intrusive behavior and are applied to two-phase flowinvestigations. Until now, the most commonly used technique to determine the droplet size is the Phase Doppler Anemogranulometry, although it is time consuming for an overall injector characterization. An imaging technique called Planar Droplet Sizing has been used to offer an alternative and provide a spatially-resolved 2D map of the Sauter Mean Diameter (SMD). The measurement is based on the ratio between laser-induced fluorescence and scattered light intensities which are assumed to be proportional respectively to the droplet volume and droplet surface area. However, previous studies revealed that the dependence of fluorescence intensity on the droplet volume can be altered by the absorption of light in the liquid. The scattered light intensity depends on the scattering angle and intensity variations within the field of view must be avoided.The aim of this study is to make the PDS technique operational for a Jet A-1 kerosene spray. A strong absorption of liquid kerosene appears under UV excitation at 266 nm making the technique unsuitable. Under visible excitation at 532 nm, a fluorescent tracer (Pyrromethene 597) must be added to the kerosene to enhance the fluorescence signal. To prevent scattered light intensity variations within the field of view, an optimal scattering angle close to 115° is required. An image processing algorithm is proposed in order to reduce the effects ofmultiple scattering.DOI: http://dx.doi.org/10.4995/ILASS2017.2017.4698

scholarly journals A many-body dissipative particle dynamics with energy conservation study of droplets icing on microstructure surfaces

2021 ◽  
Vol 3 (1) ◽  
Author(s):  
Chenyang Wang ◽  
Xiao Wu ◽  
Pengfei Hao ◽  
Feng He ◽  
Xiwen Zhang
Keyword(s):  
Contact Angle ◽  
Dissipative Particle Dynamics ◽  
Real Life ◽  
Transfer Model ◽  
Change Model ◽  
Droplet Volume ◽  
Many Body ◽  
Cold Surface ◽  
One Dimensional ◽  
Large Factor

AbstractDroplets icing has important applications in real life. The icing process of droplets on microstructure is explored based on the MDPDE method in this study. Firstly, the correctness of the heat transfer model was verified by one-dimensional heat conduction simulation, and then the feasibility of the phase change model was verified by investigating the icing process of droplets. The influence of cold surface temperature, droplet volume and contact angle on freezing time of droplets was discussed, and it was found that the temperature of cold surfaces had a greater effect on freezing. We finally explored the influence of different microstructure surfaces on the icing of droplets, and results showed that the presence of microstructures greatly enhanced the anti-icing effect of the surface. In our research, the contact angle is a relatively large factor affecting the icing of droplets. In addition, it was discovered that the droplet had the strongest ability to delay freezing on the surface of triangle microstructures with a contact angle of 157.1°.

scholarly journals Design, modeling, and performance analysis of a new dispensing system based on compliant mechanism

2020 ◽  
Vol 103 (2) ◽  
pp. 003685042092389
Author(s):  
Junfeng Hu ◽  
Xinying Zhao
Keyword(s):  
Life Science ◽  
Compliant Mechanism ◽  
Semiconductor Industry ◽  
Future Application ◽  
Rapid Manufacturing ◽  
Driving Voltage ◽  
Droplet Volume ◽  
Forming Process ◽  
And Performance ◽  
Good Agreement

Jet dispenser is widely used in microelectronic packaging, semiconductor industry, life science, and rapid manufacturing fields. As the requirement for dispensing accuracy and speed become higher and higher, especially for viscous materials, the traditional mechanisms cannot meet the high precision dispensing. This paper presents a new jetting dispenser using the complaint mechanism with amplifier components to design the dispenser, which gain the motion and force from the elastic deformation of flexible hinges. To describe the mechanical property of the jetting dispenser, the model of the jetting dispenser was built by employing a pseudo-rigid-body method. To predict accurately droplet volume, we established the model by describing the forming process of droplet. Furthermore, the errors of the droplet volume were analyzed based on the model. The prototype of the dispenser was built and the effects of driving voltage, radius of spray chamber, glue supply pressure, glue viscosity, and turn-on time of hammer on the droplet were analyzed experimentally. The analytical results are in good agreement with experimental results, which the advantages of the presented jetting dispenser with a new design concept are validated. This research provided a new idea and modeling method for the future application of the dispensing system.

WETTING AND PREWETTING PHENOMENA IN NEMATIC LIQUID CRYSTAL DISK-LIKE DROPLET

2019 ◽  
Vol 26 (04) ◽  
pp. 1850171
Author(s):  
ERFAN KADIVAR ◽  
SHAHRAM AHMADI DARANI
Keyword(s):  
Differential Equation ◽  
Boundary Layer ◽  
Phase Diagram ◽  
Free Energy ◽  
Liquid Crystal ◽  
Boundary Layer Transition ◽  
Layer Transition ◽  
Critical Droplet ◽  
Quadratic Surface ◽  
Maxwell Construction

We present a theoretical investigation of wetting and prewetting phenomena in a nematic-disk like droplet under a concentric anchoring configuration. Our theoretical model is based on Landau–de Gennes free energy together with a quadratic surface energy. By using the Maxwell construction, we numerically solve the Euler–Lagrange differential equation. The occurrence of boundary layer transition is summarized in the phase diagram scanned by temperature and surface potential. We find that prewetting phenomenon disappear below a critical droplet size and critical temperature.

Exciplex Fluorescence Thermometry of Falling Hexadecane Droplets

1992 ◽  
Vol 114 (2) ◽  
pp. 450-457 ◽  
Author(s):  
T. R. Hanlon ◽  
L. A. Melton
Keyword(s):  
Droplet Radius ◽  
Droplet Volume ◽  
Sharp Rise ◽  
Optical Sampling ◽  
Fluorescence Thermometry ◽  
Exciplex Fluorescence

Exciplex fluorescence thermometry has been used to measure the temperature of 283 micron hexadecane droplets falling through a quiescent, oxygen-free, approximately 500°C ambient. After a period of negligible change, the derived droplet temperatures exhibit a sharp rise of about 100°C followed by a gentle increase to approximately 200°C. The derived temperatures, although averaged over most of the volume of the droplet, still provide some evidence of internal processes in the droplet due to the partially selective optical sampling of the droplet volume, in which fluorescence from the region between 0.50 and 0.75 of the droplet radius contributes disproportionately. At longer times, the droplet is presumed to be approximately homogeneous, and the exciplex fluorescence thermometry measurements provide accurate, interpretable temperatures for the freely falling droplets.

Effect of protein type, concentration and oil droplet size on the formation of repulsively jammed elastic nanoemulsion gels

Soft Matter ◽  
2019 ◽  
Vol 15 (47) ◽  
pp. 9762-9775 ◽  
Author(s):  
Aakash Patel ◽  
Athira Mohanan ◽  
Supratim Ghosh
Keyword(s):  
Whey Protein ◽  
Droplet Size ◽  
Sodium Caseinate ◽  
Oil Droplet ◽  
Critical Droplet ◽  
Oil In Water ◽  
Oil Droplet Size

Sodium caseinate (SC)-stabilized 40% oil-in-water nanoemulsions (NEs) could be transformed into elastic gels below a critical droplet size due to increase in ϕeff by a thicker steric barrier of SC, while whey protein (WPI)-stabilized NEs remained liquid due to thinner steric barrier of WPI.

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