Influence of Pattern Geometry of Hybrid Surfaces on Dropwise Condensation Heat Transfer and Droplet Dynamics

The scope of combining two wettability regions is to impact the droplet dynamic behaviors, manipulate the droplets’ mobility and enhance condensation heat transfer. Hydrophobic-hydrophilic hybrid patterns can promote the heat transfer, droplet-renewal frequency and enhance the droplets’ removal during condensation. With regard of condensation on hybrid surfaces, the geometry of the patterns has a significant influence on droplets departure frequency and heat transfer performance. Therefore, different patterns geometries (circle, ellipse, and diamond) have been developed on horizontal copper tubes at atmospheric pressure. All the patterns have the same size, and the same identical gap as well between the adjacent patterns. Results show that the diamond hybrid surface has the best performance compared with ellipse, circles hybrid surfaces at the same pattern area with same neighbor gap between two patterns and complete dropwise However, the circle and ellipse hybrid surfaces outperform lower performance compared to complete dropwise surface. The heat transfer rate for the diamond hybrid surface is 15% higher than complete dropwise surface when the gap is 0.5mm. This study clearly demonstrated the effect of pattern’s geometry regarding maximum condensation heat transfer rate and droplet departure frequency.