Abstract: To strengthen the heat transfer of pure steam condensation, based on the idea of cooperative drainage, a bilayer surface of mastoid + stripe is designed and prepared：one layer was a superhydrophilic mastoid surface, and the other is a hydrophilic-superhydrophobic stripe surface. Condensation heat transfer experiments are conducted in a pure steam environment. The results show that the striped surface strengthen the condensation heat transfer performance. As the subcooling degree is 7.0 K, the condensation heat transfer coefficient is 1.39 times that of a smooth copper surface. However, the mastoid + stripe bilayer surface has a better heat transfer performance, the condensation heat transfer coefficient can be increased to 2.14 times that of smooth copper surface under the same working conditions. To acquire the mechanism of enhancing condensation heat transfer performance, a series of visualization experiments and force analysis are carried out. It is found that the condensation droplets in the superhydrophobic area could be quickly separated by the driving force from the mastoid + streak surface. Therefore, the condensation heat resistance is greatly reduced and the corresponding condensation heat transfer is greatly enhanced.

Key words: synergistic drainage, interfacial tension, condensation heat transfer, bilayer surface, wettability