Wettability effect on droplet growth behaviors during dropwise condensation

Document Type

Conference Proceeding

Publication Date



Department of Mechanical Engineering-Engineering Mechanics


The present study examines the transient characteristics of droplet growth and heat transfer during dropwise condensation process on different hydrophobic surfaces. The self-Assembled monolayer (SAM) of n-octadecyl mercaptan was coated on the surface to change the surface wettability with the contact angles of 148° and 124°. A Canon EOS 7D camera and an Infinity K2 lens were used to capture the spontaneous images during condensation. From the experiment, three regimes were observed: in the first regime where the droplets were formed with nearly homogenous pattern, the heat transfer coefficient increased rapidly. In the second regime, both the droplet size and the liquid area fraction increased. In the third regime, coalescence among larger droplets was dominant, causing the decrease in the liquid area fraction with time. Moreover, the measured fall-off time was faster in the case with higher contact angle because of relatively low surface energy.

Publisher's Statement

© Copyright 2015 by ASME. Publisher’s version of record: https://doi.org/10.1115/IMECE2015-52930

Publication Title

ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE)