Abstract
Droplets on the superhydrophobic surface can fall off the surface spontaneously, which greatly promote dropwise condensation. This study considers a continuous droplet condensation process including droplet growth and droplet jumping. A droplet growth model considered NCG is developed and droplet jumping is simulated using VOF (Volume Of Fluid) model. Al–based superhydrophobic surfaces are prepared using chemical deposition and etching method. The Al-based superhydrophobic surface has a contact angle of 157°±1° and a rolling angle of 2°±1°. An observation experiment is designed to observe droplet jumping on superhydrophobic surface using a high– speed camera system. The result of droplet growth model shows a good match with experimental data in mid-term of droplet growth. Fordroplet jumping, simulation and experiment results show that droplet jumping of different diameter hasa universality in a non–dimensional form. The jumping process can be divided into 3 stages and droplet vibration is observed.
Highlights
Dropwise condensation has a higher heat transfer coefficient, which can be applied for heat transfer enhancement[1, 2]
Many studies have proven that droplets on a superhydrophobic surface with high contact angle and rolling angle can fall off the surface spontaneously, which greatly promote dropwise condensation[1,2,3,4,5,6]
Considering the influence of surface wettability, Kim et al[4] expanded droplet thermal model to surface with contact angle larger than 90° and gave the calculation of curvature thermal resistance in droplet growth model based on heat transfer theory
Summary
Dropwise condensation has a higher heat transfer coefficient, which can be applied for heat transfer enhancement[1, 2]. Considering the influence of surface wettability, Kim et al[4] expanded droplet thermal model to surface with contact angle larger than 90° and gave the calculation of curvature thermal resistance in droplet growth model based on heat transfer theory. Compared two growth models: CB (constant base) model and CCA (constant contact angle) model on the superhydrophobic surface with an ESEM observation for droplets growth They found that droplet diameter increases in a step like fashion of CB and CCA mode. The result of droplet growth model shows a good match with experimental data in mid-term of droplet growth while in the early stage and late stage the model has significant differences from experiment data because of the coalesce between microdroplets.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
