Molecular dynamics simulations of nanoscale boiling on mesh-covered surfaces
S Ahmad and W Deng and HQ Liu and SA Khan and JT Chen and JY Zhao, APPLIED THERMAL ENGINEERING, 195, 117183 (2021).
The surfaces with micro/nano porous mesh structures have shown great potentials to significantly enhance the boiling heat transfer performance. In this work, the nonequilibrium molecular dynamics simulations are carried out to investigate the boiling process on the mesh-covered copper surfaces with argon as a working fluid. Three different type of surfaces are incorporated: a porous mesh-covered surface (a surface with pores in between the mesh wires and base solid surface), a simple mesh-covered surface (a surface without pores under mesh wires) and a plain surface. The simulations results showed that both mesh-covered surfaces have significant effects on the density distribution of the system, argon temperature and evaporation rate. The heat transfer from the solid surface to argon is significantly enhanced for both mesh-covered surfaces due to larger solid-liquid contact area as compared to plain surface. Furthermore, different mechanisms of boiling process are observed for porous mesh-covered surface and other two surfaces. The argon atoms near the solid surface are quickly heated, forming a vapor layer which causes the separation of the liquid as the big clusters for both simple mesh-covered surface and plain surface. But liquid is present in the pores under the mesh wires which evaporates and delays the formation of vapor layer for the porous mesh-covered surface, and thus, when liquid cluster is separating from the solid surface the argon temperature, evaporation rate and heat flux are enhanced significantly as compared to simple mesh-covered surface and plain surface. Furthermore, some liquid remains in pores even after the separation of the liquid cluster from the solid surface, which evaporates with time while the liquid cluster rises up, further increasing the argon temperature and evaporation rate for the porous mesh-covered surface. It is found that simple and porous mesh-covered surfaces increased the evaporation rate by 19.16% and 23.89%, respectively. Moreover, the porous mesh-covered surface showed highest energy exchange rate and heat flux.
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