Wetting controlled boiling at the nanoscale

TL;DR

This study uses molecular dynamics simulations to reveal that nanoscale boiling is a heterogeneous, wetting-dependent process influenced by interfacial thermal conductance, challenging the traditional homogeneous spinodal-based view.

Contribution

It demonstrates that nanoscale boiling occurs at a wetting-dependent onset temperature, often below the spinodal temperature, and is controlled by interfacial thermal conductance, providing new insights into boiling mechanisms.

Findings

Nanoscale boiling is heterogenous and occurs at a wetting-dependent onset temperature.

Boiling can occur at temperatures 100 K below the spinodal temperature for weakly wetting surfaces.

Interfacial thermal conductance decreases before phase change, controlling nucleation times.

Abstract

Boiling is the out-of-equilibrium transition which occurs when a liquid is heated above its vaporization temperature. At the nanoscale, boiling may be triggered by irradiated nanoparticles immersed in water or nanocomposite surfaces and often results in micro-explosions. It is generally believed that nanoscale boiling occurs homogeneously when the local fluid temperature exceeds its spinodal temperature, around 573 K for water. Here, we employ molecular dynamics simulations to show that nanoscale boiling is an heterogenous phenomenon occuring when water temperature exceeds a wetting dependent onset temperature. This temperature can be 100 K below spinodal temperature if the solid surface is weakly wetting water. In addition, we show that boiling is a slow process controlled by the solid-liquid interfacial thermal conductance, which turns out to decrease significantly prior to phase change yielding long nucleation times. We illustrate the generality of this conclusion by considering both a spherical metallic nanoparticle immersed in water and a solid surface with nanoscale wetting heterogeneities. These results pave the way to control boiling using nanoscale patterned surfaces.