Numerical study on condensation heat transfer in vertical channel with hydrophilic-hydrophobic patterned surfaces

Abstract

A numerical study was conducted of condensation phenomenon in a vertical channel with hydrophilic-hydrophobic patterned surfaces. The Volume of Fluid (VOF) method was adopted to detect the phase interface and the Lee's phase-change model was used. An Artificial Neural Network (ANN) model was constructed to predict the heat transfer coefficient using experimental data and model was used for the numerical validation. From the force balance around a liquid droplet, a theoretical relationship between the inflow velocity and the droplet movement angle was derived. The size, arrangement and angle of the pattern were considered as design variables, together with the channel height. The results showed that a decrease of the pattern size and increases of pattern angle and channel height caused heat transfer augmentation. In contrast, increased pressure drop was observed as the pattern size and the channel height decreased and the pattern angle increased. Bridging droplets in the channel were observed depending on the arrangement of patterns between two plates; surfaces with staggered patterns showed better performance. It was found that the thermal performance of the plate was highly influenced by the pattern angle, because of the performance of the condensate liquid removal.