The connection between wall wettability, boiling regime and symmetry breaking for nanoscale boiling

LY Zhang and JL Xu and JP Lei and GL Liu, INTERNATIONAL JOURNAL OF THERMAL SCIENCES, 145, 106033 (2019).

DOI: 10.1016/j.ijthermalsci.2019.106033

The effect of surface wettabilities on nanoscale boiling is investigated using molecular dynamics simulation. Argon particles are filled in- between two solid walls to form a vapor-liquid system. Surface wettability and fluid densities are controlled by the solid-liquid interaction intensity and the number of argon particles, respectively. A complete boiling regime map is presented. M high fluid densities (rho > 0.8 rho(sat) where rho(sat) is the saturation liquid density), non- boiling regime occurs independent on surface wettabilities. At low fluid densities (P <= 0.8 rho(sat)), Leidenfrost, heterogeneous and homogeneous regimes consecutively occur when surface wettabilities are changed from super-hydrophobicity to super-hydrophilicity. Leidenfrost regime is recognized as a nanoscale lotus-leaf-effect. Both Leidenfrost and homogeneous regimes generate symmetric fluid densities. For heterogeneous nucleation, bubble nucleation occurs on either one of the two walls. Because the symmetry of the stable state of the system is lower than the symmetry of the solid-fluid interaction potentials, a small disturbance may change the wall to nucleate a bubble embryo, resulting in asymmetric fluid densities to cause the symmetry breaking. The present study enhances the understanding of nanoscale boiling.

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