An experimental study on the plate edge effect of frosting characteristics for horizontal flat cold plates with surface wettability considered

Frosting happens frequently in nature and industry and the accumulated frost layer always plays negative effects on a variety of applications. To clarify the frosting characteristics of cold plates with different surface wettability considering the plate edge effect, the frosting experiments of horizontal flat cold plates with hydrophilic, hydrophobic and superhydrophobic surfaces were carried out under forced convection. The results show that, different from the large condensed droplets in the edge-affected regions of the hydrophilic and hydrophobic surfaces, which are small and few on the superhydrophobic surface. The area-average equivalent contact diameter and coverage area ratio of condensed droplets decrease with the increase of surface wettability. The average freezing propagation velocity in the edge-affected region of the superhydrophobic surface is 166.4 × 10⁻⁶ m/s, which is 81.8% and 54.5% lower than those on hydrophilic and hydrophobic ones, respectively. And the maximum frost layer growth rate of the superhydrophobic surface is 3.36 × 10⁻⁶ m/s, which is 2.78 and 2.30 times the two other ones. The frost layer surface roughness of the superhydrophobic surface is 85.1 × 10⁻⁶ m, which is 27.8% and 74.7% higher than those on hydrophilic and hydrophobic ones, respectively. This study can reveal the time–space frosting characteristics in the edge region of horizontal cold plates and provide a reference for anti-frosting in practical applications.