Experimental condensation study of vertical superhydrophobic surfaces assisted by hydrophilic constructal-like patterns

The effect of hydrophilic constructal-like patterns on the condensate mass flow rate production of superhydrophobic vertical test sections is discussed. The surface patterning, which presents a branching topology, is obtained by coating selected areas of the condensation surface with a commercial product. In total, five different designs were tested, three with a branched topology having coated/clear area fractions of approximately 30%, 50% and 70%, in addition to fully clear and fully coated test sections. The condensation performance of each test section was measured in the presence of non-condensable gases inside a climate-controlled chamber, which allowed independent adjustment of its internal temperature and humidity. Condensation measurements indicate that for some cases, averaged improvements ranged between 7.4% and 17.5% when a test section with an area fraction of 70% is compared with clear and fully coated surfaces, respectively, considering the climate-controlled chamber is kept with a relative humidity of nearly 80%. Additionally, a qualitative image-based analysis of the condensation process revealed that the superhydrophobic/hydrophilic interface arguably aids the droplet detachment and could, potentially, guide/direct the draining flow in real systems.