Water droplet dynamics on a heated nanowire surface

Abstract A sliding droplet over the silicon oil film is examined and the dynamics of droplet motion are explored. The solution crystallized wafer surfaces are silicon oil impregnated and the uniform thickness oil film is realized. A recording facility operating at high-speed and the tracker program are used to monitor and evaluate the droplet dynamics during droplet sliding. The sliding behavior and flow generated in the droplet fluid are predicted by adopting the experimental terms. Findings revealed that the crystallized surface possesses the texture composing of spherules and fibrils, which give rise to 132o ± 4o contact angle and 38o ± 4o hysteresis. Oil impregnation on the crystalized surface improves the optical transmittance by three times for 250 nm to 500 nm wavelength range and almost 1.5 times after 500 nm to 850 nm wavelengths of the optical spectrum. The oil rim and ridges are developed in sliding water droplet vicinity while influencing droplet motion; however, this influence is estimated as almost 12% of droplet gravitational energy change during sliding. A circulatory flow is developed inside the droplet fluid and the maximum velocity in the droplet fluid changes as the droplet location changes on the oil surface during its sliding.

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Water droplet dynamics in a dead-end anode proton exchange membrane fuel cell

Applied Energy ◽

10.1016/j.apenergy.2018.10.001 ◽

2019 ◽

Vol 233-234 ◽

pp. 300-311 ◽

Cited By ~ 11

Author(s):

Asif Soopee ◽

Agus P. Sasmito ◽

Tariq Shamim

Keyword(s):

Fuel Cell ◽

Water Droplet ◽

Proton Exchange Membrane ◽

Proton Exchange ◽

Droplet Dynamics ◽

Dead End ◽

Exchange Membrane

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Numerical Study of Water Droplet Heat Removal and Dynamics During its Impact Onto the Micro-Pillar Array at Elevated Temperature

Volume 7: Decontamination and Decommissioning, Radiation Protection, and Waste Management; Mitigation Strategies for Beyond Design Basis Events ◽

10.1115/icone26-81171 ◽

2018 ◽

Author(s):

Beni Mehrdad Shahmohammadi ◽

Shangzhen Xie ◽

Jiyun Zhao

Keyword(s):

Heat Transfer ◽

Level Set Method ◽

Level Set ◽

Solid Surface ◽

Water Droplet ◽

Heat Removal ◽

Spray Cooling ◽

Optimal Size ◽

Droplet Dynamics ◽

Micro Pillars

The spray cooling and heat removal efficiency is one of the important aspect of nuclear thermalhydraulics and safety, especially for passive containment cooling after severe accidents. In order to design and optimize these systems effectively, computer modelling of the underlying mechanism of the liquid drop interaction with the hot solid surface would be necessary. Therefore, completeness, accuracy and reliability of the models that are being used in such sensitive areas are vital to the society and environment. Furthermore, the current powerful computer resources need to be fully exploited, so that the precision and the accuracy of the obtained computational results would be further enhanced. Nowadays, Volume-Of-Fluid (VOF) method is widely used in simulating the droplet dynamics, however these models provide estimations that are different in certain extents compare to the experimental results. In present work, we have used the level-set method to study the droplet dynamics and heat removal when the water droplet impact on the surface with different morphologies. The developed model which is based on the finite element method (FEM) has been benchmarked with previously performed experiments regarding the droplet bouncing on a flat hydrophobic surface; these estimations were in a good agreement with the previously published results. Moreover, hot solid surfaces with presence of micro-pillar has been considered to perform sensitivity study for different sizes of the micro-pillars and water droplets. In addition, it has been found that the heat transfer and droplet dynamic behavior would significantly vary in scenarios when the micro-pillars are presents in compare to a flat solid surface; it is observed that a better droplet spreading can be obtained with optimal size of micro-pillars that are present underneath of the droplet axial trajectory. The present study and the model would add valuable information to the field of heat transfer in aspect of spray cooling by investigating the feasibility of using the level-set method for a better estimation of fluid and heat transfer related results.

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