Experimental study on anti-frosting performance of superhydrophobic surface under high humidity conditions

Abstract

• Frosting experiment of superhydrophobic surface under high humidity was performed. • Self-jumping of condensate droplets always existed at early stage of frosting. • The freezing time of droplets was delayed compared with that of bare surface. • Ambient humidity had effects on frost crystal pattern and frost layer thickness. • Superhydrophobic surface had good anti-frosting performance under high humidity. The ambient humidity has a significant influence on the frosting characteristics of cold surface. In order to achieve the anti-frosting performance of superhydrophobic surface under high humidity conditions, visualization were performed to study the frosting characteristics of superhydrophobic surface at relative humidity of 65%, 75%, 85% and 95%. The absolute humidity was 6.11, 7.05, 7.99 and 8.93 g/m 3 , respectively. Experimental results showed that the phenomenon of merging and self-jumping of condensate droplets always existed at early stage of frosting, even under high humidity conditions. Although the freezing time of condensate droplets decreased with the increase of ambient humidity, it was delayed compared with bare surface. At the frost layer growth stage, the ambient humidity had effects on the frost crystal pattern and frost layer thickness of superhydrophobic surface. When the relative humidity was 65%, the surface was covered with sword-shaped frost crystals, while the frost layer was thicker and denser at 95%. The frost layer thickness of superhydrophobic surface was 0.78, 0.58, 0.64 and 0.74 times of that of bare surface, when the relative humidity was 65%, 75%, 85% and 95%, respectively. This indicated that the superhydrophobic surface still had good anti-frosting performance under high humidity conditions.