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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

Snapshots of liquid argon boiling process 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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Fig5: Snapshots of liquid argon boiling process for the case with a 310 K heated source. (a) Surface 0, (b) surface 1, (c) surface 2, and (d) surface 3.

Mentions: The snapshots of the entire simulation domain in the y-z plane at representative simulation times are shown in Figure 5. At the beginning of the process, two phase interfaces in each case, including the interface between solid wall and liquid argon and the interface between liquid argon and vapor argon, have clear divisions from 0 to 1 ns. For surface 0, liquid argon keeps its original state from 0 to 2 ns. As time goes on, it is obvious that the liquid argon atoms enter into the vapor region gradually, and almost all of the liquid argon atoms escape from the superheated wall to the vapor region until 6 ns. For surface 1, the entire separation of the liquid argon film from the solid surface is completed at about 1.2 ns and then they become large clusters that move upward with evaporation. For surface 2 and surface 3, due to bigger contact surface area with fluid, the separation of the liquid starts at about 1.1 ns, only a small cluster of liquid moves upward, and the rest of the liquid moves as individual atoms or in a dispersed tiny cluster. As can be seen in Figure 5a, the explosive boiling and evaporation process lasts longer, and the system requires additional time to reach the equilibrium state for surface 0. In addition, with the increasing height of the nanoposts on the surface, the lesser the time the system needs to complete the boiling and evaporation of the liquid argon. It is worth to mention that comparing surface 2 with surface 3, these two systems take almost equal time to get equilibrium, so a reasonable height of nanoposts should be considered in simulation with the idea of time conservation.Figure 5


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)

Snapshots of liquid argon boiling process 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

Fig5: Snapshots of liquid argon boiling process for the case with a 310 K heated source. (a) Surface 0, (b) surface 1, (c) surface 2, and (d) surface 3.
Mentions: The snapshots of the entire simulation domain in the y-z plane at representative simulation times are shown in Figure 5. At the beginning of the process, two phase interfaces in each case, including the interface between solid wall and liquid argon and the interface between liquid argon and vapor argon, have clear divisions from 0 to 1 ns. For surface 0, liquid argon keeps its original state from 0 to 2 ns. As time goes on, it is obvious that the liquid argon atoms enter into the vapor region gradually, and almost all of the liquid argon atoms escape from the superheated wall to the vapor region until 6 ns. For surface 1, the entire separation of the liquid argon film from the solid surface is completed at about 1.2 ns and then they become large clusters that move upward with evaporation. For surface 2 and surface 3, due to bigger contact surface area with fluid, the separation of the liquid starts at about 1.1 ns, only a small cluster of liquid moves upward, and the rest of the liquid moves as individual atoms or in a dispersed tiny cluster. As can be seen in Figure 5a, the explosive boiling and evaporation process lasts longer, and the system requires additional time to reach the equilibrium state for surface 0. In addition, with the increasing height of the nanoposts on the surface, the lesser the time the system needs to complete the boiling and evaporation of the liquid argon. It is worth to mention that comparing surface 2 with surface 3, these two systems take almost equal time to get equilibrium, so a reasonable height of nanoposts should be considered in simulation with the idea of time conservation.Figure 5

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