CFD study of Marangoni condensation heat transfer of vapor mixture on a horizontal tube

Abstract

Over the past few decades, experimental studies have been conducted on the condensation heat transfer of vapor mixtures. However, the local heat transfer characteristics of vapor mixture affected by surface tension have not been fully investigated. The present work, for the first time, suggested the CFD simulation method for the Marangoni condensation of ethanol-vapor mixture and analyzed the calculated result with flow structure. A CFD study has been performed for the condensation heat transfer of steam–ethanol mixtures on a horizontal tube to elucidate the Marangoni condensation phenomenon and the consequent heat transfer mechanism, which are difficult to fully obtain experimentally. In the present study, the numerical predictions of condensation heat transfer using a liquid film model agree well with those of the experimental results. The CFD analysis of steam–ethanol mixture compares with pure steam to clearly show the influence of surface tension on the heat transfer. In particular, when a small amount of ethanol is added to pure steam, the condensation heat transfer is enhanced because the local liquid film thickness is changed because of the surface tension gradient on the gas–liquid interface, which is caused by a concentration difference.