Solid-like Behaviors Govern Evaporative Transport in Adsorbed Water Nanofilms

Abstract

The thermophysical attributes of water molecules confined in a sub-nanometer thickness significantly differ from those in bulk liquid where their molecular behaviors start governing interfacial physics at the nanoscale. In this study, we elucidate nanothin film evaporation by employing a computational approach from a molecular perspective. As the liquid thickness decreases, the solid-like characteristics of adsorbed water nanofilms make the resistance at solid–liquid interfaces or Kapitza resistance significant. Kapitza resistances not only show a strong correlation with the surface wettability but also dominate the overall thermal resistance during evaporation rather than the resistance at evaporating liquid–vapor interfaces. Once the liquid thickness reaches the critical value of 0.5–0.6 nm, the evaporation kinetics is suppressed due to the excessive forces between the liquid and solid atoms. The understanding of molecular-level behaviors explains how a hydrophilic surface plays a role in determining evaporation rates from an atomistic perspective.

Evaporation of Water Nanodroplets on Heated Surfaces: Does Nano Matter?

“…In the past decade or so, molecular dynamics (MD) simulations, which do not rely on the major simplifying assumptions of the continuum models, have been used to gain insight into the evaporation and wetting behavior of water at the molecular level. Previous work on the evaporation of water at the molecular scale and nanoscale has been primarily focused on the wetting behavior of sessile nanodroplets as a function of size and temperature, , on the evaporation of films − and free-standing nanodroplets, , and on the quantification of accommodation coefficients, which still remains a controversial issue. , Simulations of sessile nanodroplets have shed some light into the role of hydrophobicity on their evaporative behavior; − however, previous studies have overwhelmingly focused on simple Lennard-Jones fluids, thus offering limited insight into the behavior of water nanodroplets, which is mediated by directional interactions such as hydrogen bonds. To the best of our knowledge, only Reese and co-workers have simulated the evaporation of pure sessile water nanodroplets, which they found to evaporate in CCR mode on platinum surfaces.…”

Achieving the Super Gas-Wetting Alteration by Functionalized Nano-Silica for Improving Fluid Flowing Capacity in Gas Condensate Reservoirs

“…Figure k is the distribution of water in the porous media after super gas-wetting alteration by FS1-NSP. The water in the area marked by the three red arrows has been driven out and all the throats are occupied by gas, which eliminates the phenomenon of water locking and memorably improves the flow capacity of liquid . The main reason is that the FS1-NSP has a stronger gas-wetting alteration ability, in which the nanoparticles will be adsorbed on the surface of the throat to effectively reduce the surface free energy and increase the surface roughness.…”

“…The water in the area marked by the three red arrows has been driven out and all the throats are occupied by gas, which eliminates the phenomenon of water locking and memorably improves the flow capacity of liquid. 57 The main reason is that the FS1-NSP has a stronger gas-wetting alteration ability, in which the nanoparticles will be adsorbed on the surface of the throat to effectively reduce the surface free energy and increase the surface roughness. As a result, the water cannot be spread out on the surface, which increases the displacement efficiency and improves the transmission capacity of the fluid.…”

Molecular Dynamics Simulations of Wettability, Thermal Transport, and Interfacial Liquid Structuring at the Nanoscale in Polar Solid–Liquid Interfaces

“…The TBC ( G ) is an interfacial property associated with the thermal transport resistance across different materials and can be calculated using the temperature discontinuity at the interface (Δ T int ) induced by a heat flux ( J ), such that J = G Δ T int . The TBC plays a major role in energy transport processes, such as in thin film evaporation, where the interfacial thermal resistance (inverse of the TBC) can be up to 2 orders of magnitude higher than the evaporation resistance . The TBC was calculated using a well-established NEMD formalism to determine Δ T int .…”

“…The TBC plays a major role in energy transport processes, such as in thin film evaporation, where the interfacial thermal resistance (inverse of the TBC) can be up to 2 orders of magnitude higher than the evaporation resistance. 52 The TBC was calculated using a well-established NEMD formalism to determine ΔT int . The passivated slab and the charge distribution obtained from the reactive simulations were used to create a slit by duplicating a single slab and creating a confinement that was filled with water molecules (2200−3000 molecules depending on the plane), and the distance between the slabs was slightly adjusted to avoid compressibility effects due to the capillary pressure induced by different wettability conditions.…”