Experimental study for enhancing condensation on large-scale surface using hybrid hydrophilic-hydrophobic patterns

Improving condensation on large-scale surfaces promotes a wide range of manufacturing fields. To take advantage of both dropwise and filmwise condensation properties, both hydrophobic and hydrophilic surfaces can be developed on one hybrid surface. In this paper, experimental studies were performed on vapor condensation over a flat vertical plate. Three different surfaces were utilized: hydrophilic (aluminum), hydrophobic (coated), and hybrid surfaces with distinctive hydrophilic and hydrophobic patterns. The effect of the volume flow rate of the cooling water was investigated from 5 L/min to 15 L/min. For the hybrid surfaces, three types of patterns were studied: separated holes of hydrophilic patterns (the island) with two different diameters, arrow pattern, and tree pattern. According to the results, the heat transfer rate varied as the surface conditions changed. For the aluminum surface that resulted in filmwise condensation mode, the observed heat transfer rate was less than that of the coated surface, which showed a combination of filmwise and dropwise condensation modes. For the hybrid surfaces, the observed heat transfer rate was higher than that of the coated surface. From all the surfaces in this study, the highest heat transfer rate was for the 2.0 mm diameter island pattern