Local mass and energy transports in evaporation processes from a vapor-liquid interface in a slit pore based on molecular dynamics

K Fujiwara,M Shibahara

doi:10.1063/1.5010890

Abstract

Molecular evaporation processes from a vapor-liquid interface formed in a slit-like pore were examined based on the classical molecular dynamics method, in order to elucidate a molecular mechanism of local mass and energy transports in a slit. The calculation system consisted of monatomic molecules and atoms which interact through the 12-6 Lennard-Jones potential. At first, a liquid was situated in a slit with a vapor-liquid interface, and instantaneous amounts of the mass and energy fluxes defined locally in the slit were obtained in two dimensions to reveal local fluctuation properties of the fluid in equilibrium states. Then, imposing a temperature gradient in the calculation system, non-equilibrium evaporation processes in the slit were investigated in details based on the local mass and energy fluxes. In this study, we focused on the fluid which is in the vicinity of the solid surface and in contact with the vapor phase. In the non-equilibrium evaporation processes, the results revealed that the local energy transport mechanism in the vicinity of the solid surface is different from that of the vapor phase, especially in the case of the relatively strong fluid-solid interaction. The results also revealed that the local mass transport in the vicinity of the solid surface can be interpreted based on the mechanism of the local energy transport, and the mechanism provides valuable information about pictures of the evaporation phenomena especially in the vicinity of the hydrophilic surfaces. It suggests that evaluating and changing this mechanism of the local energy transport are necessary to control the local mass flux more precisely in the vicinity of the solid surface.

Highlights

Evaporation in structures is one of the fundamental phenomena in physics and chemistry which is related to mass and energy transports, and it has drawn much attention of scientists and engineers without relation to scales at which it occurs.[1,2] In industries, controlling such evaporation phenomena is a key issue even at nanometer scales for example in the semiconductor manufacturing processes,[3] and is beneficial to other industries where heat managements are necessary.[4,5] even the theoretical description of the evaporation processes has not been fully established, which makes the accurate prediction of the evaporation rate difficult.[1]
The fluid properties of the fluctuation in the vicinity of the solid surface were examined in details to reveal molecular pictures of the local mass and energy transports in the slit
We conducted molecular dynamics simulations focusing on the fluid phase with a vapor-liquid interface in a slit-like pore in equilibrium and non-equilibrium states

Summary

Introduction

Evaporation in structures is one of the fundamental phenomena in physics and chemistry which is related to mass and energy transports, and it has drawn much attention of scientists and engineers without relation to scales at which it occurs.[1,2] In industries, controlling such evaporation phenomena is a key issue even at nanometer scales for example in the semiconductor manufacturing processes,[3] and is beneficial to other industries where heat managements are necessary.[4,5] even the theoretical description of the evaporation processes has not been fully established, which makes the accurate prediction of the evaporation rate difficult.[1].

Objectives

Results

Conclusion