Molecular dynamics study on the effect of surface wettability on the performance of water vapor condensation

Abstract

Many studies have focused on the effect of surface wettability on condensation at the nanoscale, while few studies investigated the condensation process of water vapor below 450K. However, water vapor condensation below 450K is common and important in industrial fields. In this paper, molecular dynamics method is used to study the effect of surface wettability on the performance of water vapor condensation below 450K on a copper surface, and a comparison with the performance of water vapor condensation at 450K was performed. The results show that the heat transfer performance of vapor is not the same when condensing on a hydrophilic surface and on a hydrophobic surface. It’s found that lower temperature vapor requires more time in starting to condense on a hydrophobic surface, whose heat transfer efficiency first increases gradually and finally becomes constant. For the first time the process of vapor condensation on a hydrophobic surface was divided into three stages based on the changes in heat transfer efficiency, and the heat transfer performance of each stage was analyzed. The results show that a stronger surface wettability and higher vapor temperature improve the heat transfer performance during the condensation process. Moreover, the lower the vapor temperature is, the greater the impact of the wettability is on the heat transfer efficiency, and the vapor less easily condenses on a hydrophobic surface.