Non-equilibrium Molecular Dynamics Study of Surface Wettability Effects on Pool Boiling of Water over Nanoscale Aluminum Substrate

TL;DR

This study uses non-equilibrium molecular dynamics simulations to analyze how surface wettability affects pool boiling of water on nanoscale aluminum, revealing that hydrophilic surfaces improve heat transfer and delay boiling transitions.

Contribution

It provides detailed molecular insights into the influence of surface wettability on boiling heat transfer and critical heat flux in nanoscale aluminum-water systems.

Findings

Hydrophilic surfaces increase critical heat flux (CHF).

Hydrophilic surfaces delay the Leidenfrost point.

Surface wettability significantly affects nanoscale boiling behavior.

Abstract

Non-equilibrium molecular dynamics (NEMD) simulations were used to study pool boiling of water films on an ultra-thin planar aluminum substrate as well as the effect of surface wettability. The simulation geometry is a 10 nm-thick water film on an FCC aluminum substrate heated from 300 K to 900 K. The first peak acceleration onset time of the film, as the measure of the nucleation start, has been observed. The average heating rates of the near-wall water were 0.064, 0.048, and 0.035 K/ps for hydrophilic, neutral, and hydrophobic surfaces, respectively. Boiling curves shows that the critical heat flux (CHF) equals 5216, 3979, and 2525 MW/m^2 at wall temperatures of 466, 502, and 561 K, respectively. The minimum heat flux (MHF, Leidenfrost point) is equal to 2157, 2463, and 2366 MW/m^2 at wall temperatures of 767, 784, and 746 K, respectively. Interfacial HTC remains higher for longer times under the hydrophilic condition, whereas Kapitza resistance is low initially but then increases sharply after transition to film boiling with the highest values for the hydrophobic surface. In general, the results demonstrate that engineering aluminum wettability towards intense hydrophilicity diminishes the explosive boiling point, increases CHF, and enhances nanoscale thermal management performance.