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Numerical experiments on evaporation and explosive boiling of ultra-thin liquid argon film on aluminum nanostructure substrate.

Wang W, Zhang H, Tian C, Meng X - Nanoscale Res Lett (2015)

Bottom Line: Those simulations begin with an initial configuration for the complex liquid-vapor-solid system, followed by an equilibrating system at 90 K, and conclude with two different jump temperatures, including 150 and 310 K which are far beyond the critical temperature.The space and time dependences of temperature, pressure, density number, and net evaporation rate are monitored to investigate the phase transition process on a flat surface with and without nanostructures.The simulation results reveal that the nanostructures are of great help to raise the heat transfer efficiency and that evaporation rate increases with the nanostructures' height in a certain range.

View Article: PubMed Central - PubMed

Affiliation: Department of Electrical and Mechanical Engineering, Xidian University, No. 2 South Taibai Road, Xi'an, Shaanxi 710071 China ; State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University, No. 99 Yanxiang Road, Xi'an, Shaanxi 710054 China ; Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China.

ABSTRACT
Evaporation and explosive boiling of ultra-thin liquid film are of great significant fundamental importance for both science and engineering applications. The evaporation and explosive boiling of ultra-thin liquid film absorbed on an aluminum nanostructure solid wall are investigated by means of molecular dynamics simulations. The simulated system consists of three regions: liquid argon, vapor argon, and an aluminum substrate decorated with nanostructures of different heights. Those simulations begin with an initial configuration for the complex liquid-vapor-solid system, followed by an equilibrating system at 90 K, and conclude with two different jump temperatures, including 150 and 310 K which are far beyond the critical temperature. The space and time dependences of temperature, pressure, density number, and net evaporation rate are monitored to investigate the phase transition process on a flat surface with and without nanostructures. The simulation results reveal that the nanostructures are of great help to raise the heat transfer efficiency and that evaporation rate increases with the nanostructures' height in a certain range.

No MeSH data available.


Related in: MedlinePlus

Number density profiles for the case with a 310 K heated source. (a) Surface 0, (b) surface 1, (c) surface 2, and (d) surface 3.
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Fig6: Number density profiles for the case with a 310 K heated source. (a) Surface 0, (b) surface 1, (c) surface 2, and (d) surface 3.

Mentions: The density number profile of the high superheated temperature process in the z-axis as a function of time for different surfaces is shown in Figure 6, which indicates the distribution characteristics of the argon atoms. Considering the three phases in the simulation system, the distance between the solid wall and the top boundary of the simulation domain is divided into thirty-four equal slices. The number of molecules in each slice is counted to obtain the density of each slice in the computational domain. It is a clear phenomenon that the liquid film moves away from the solid surface at different times and that the maximum point of number density decreases with the increase of time. The region of density jumps appearing in the curves indicates the locations of the floating liquid argon. For example, due to slow evaporation, surface 0 has not separated from the flat surface until 6 ns which can be captured in Figure 6a. At t = 1.2 ns, the liquid cluster is between 10 and 14 nm for surface 1, between 13 and 17 nm for surface 2, and between 18 and 22 nm for surface 3, which means that with the increasing height of the nanoposts, the liquid cluster moves and evaporates faster. The reason why the number density gradually flattens after each jump is the disappearance of the interface between the liquid and gas phases.Figure 6


Numerical experiments on evaporation and explosive boiling of ultra-thin liquid argon film on aluminum nanostructure substrate.

Wang W, Zhang H, Tian C, Meng X - Nanoscale Res Lett (2015)

Number density profiles for the case with a 310 K heated source. (a) Surface 0, (b) surface 1, (c) surface 2, and (d) surface 3.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4401484&req=5

Fig6: Number density profiles for the case with a 310 K heated source. (a) Surface 0, (b) surface 1, (c) surface 2, and (d) surface 3.
Mentions: The density number profile of the high superheated temperature process in the z-axis as a function of time for different surfaces is shown in Figure 6, which indicates the distribution characteristics of the argon atoms. Considering the three phases in the simulation system, the distance between the solid wall and the top boundary of the simulation domain is divided into thirty-four equal slices. The number of molecules in each slice is counted to obtain the density of each slice in the computational domain. It is a clear phenomenon that the liquid film moves away from the solid surface at different times and that the maximum point of number density decreases with the increase of time. The region of density jumps appearing in the curves indicates the locations of the floating liquid argon. For example, due to slow evaporation, surface 0 has not separated from the flat surface until 6 ns which can be captured in Figure 6a. At t = 1.2 ns, the liquid cluster is between 10 and 14 nm for surface 1, between 13 and 17 nm for surface 2, and between 18 and 22 nm for surface 3, which means that with the increasing height of the nanoposts, the liquid cluster moves and evaporates faster. The reason why the number density gradually flattens after each jump is the disappearance of the interface between the liquid and gas phases.Figure 6

Bottom Line: Those simulations begin with an initial configuration for the complex liquid-vapor-solid system, followed by an equilibrating system at 90 K, and conclude with two different jump temperatures, including 150 and 310 K which are far beyond the critical temperature.The space and time dependences of temperature, pressure, density number, and net evaporation rate are monitored to investigate the phase transition process on a flat surface with and without nanostructures.The simulation results reveal that the nanostructures are of great help to raise the heat transfer efficiency and that evaporation rate increases with the nanostructures' height in a certain range.

View Article: PubMed Central - PubMed

Affiliation: Department of Electrical and Mechanical Engineering, Xidian University, No. 2 South Taibai Road, Xi'an, Shaanxi 710071 China ; State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University, No. 99 Yanxiang Road, Xi'an, Shaanxi 710054 China ; Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China.

ABSTRACT
Evaporation and explosive boiling of ultra-thin liquid film are of great significant fundamental importance for both science and engineering applications. The evaporation and explosive boiling of ultra-thin liquid film absorbed on an aluminum nanostructure solid wall are investigated by means of molecular dynamics simulations. The simulated system consists of three regions: liquid argon, vapor argon, and an aluminum substrate decorated with nanostructures of different heights. Those simulations begin with an initial configuration for the complex liquid-vapor-solid system, followed by an equilibrating system at 90 K, and conclude with two different jump temperatures, including 150 and 310 K which are far beyond the critical temperature. The space and time dependences of temperature, pressure, density number, and net evaporation rate are monitored to investigate the phase transition process on a flat surface with and without nanostructures. The simulation results reveal that the nanostructures are of great help to raise the heat transfer efficiency and that evaporation rate increases with the nanostructures' height in a certain range.

No MeSH data available.


Related in: MedlinePlus