Molecular dynamics simulation on effects of nanostructure on interfacial thermal resistance during condensation

Abstract

Heat transfer with phase change is applied in various industrial fields such as power generation industry, air conditioning systems and cooling of electronic devices. In the above mentioned industrial devices, condensation is one of the important processes, and the enhancement of heat transfer coefficients in condensation processes benefits us from a thermal efficiency point of view. In the case of condensation on a solid surface, it is known that condensation heat transfer coefficients change through the modification of physical and chemical properties of condensation surface, and the enhancements of condensation heat transfer coefficient by designed nano and micro structure pattern on a heat transfer surface have been reported (Chen et al., 2011; Miljikovic et al., 2013; Hou et al., 2015). However, there is limited general knowledge on how the structures influence energy transfer during the condensation. In order to understand the effects of the structures at the nanometer scale (nanostructures) attached to a heat transfer surface in the condensation processes, a molecular dynamics point of view is necessary because the molecular-scale condensation occurs on a surface at the nanometer scale at the initial stage of the condensation heat transfer phenomena. Before now, a number of studies have been carried out to estimate the heat transfer of molecular scale (Kimura and Maruyama, 2002; Vera and Yildiz, 2015) and the effects of the nanostructures on the heat transfer surface during condensation (Uno et al., 2016, 2018; Gao et al., 2019). However, there were few researches which investigated the effect of the local segment of the nanostructure on the heat transfer surface during condensation. Therefore, we investigated the condensation behavior and heat transfer mechanism in each segment of the surface with the nanostructure, which would be the basis of the detailed design of the heat transfer surface with the optimal nanostructured pattern which realizes high condensation heat transfer coefficient. In this study, we especially focused on the condensation behaviors and the local heat transfer in condensation processes on a solid surface with a cuboid structure. The classical molecular dynamics Akito FUJII*, Kunio FUJIWARA*, Yoshitaka UEKI* and Masahiko SHIBAHARA* *Graduate School of Engineering, Osaka University 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan E-mail: fujii.akito.mte@gmail.com Received: 17 March 2020; Revised: 11 May 2020; Accepted: 1 June 2020