Effect of contact angle on water droplet freezing process on a cold flat surface

The effect of contact angle on water droplet freezing process on a cold flat surface under natural convection conditions was experimentally investigated. A series of hydrophobic surfaces with different contact angles were prepared by solution immersion. The contact angles of these surfaces were varied from 97.2° to 154.9°. Comparative observations of water droplet freezing processes were carried out on both plain copper surface and these hydrophobic surfaces under the same conditions. The experimental results showed that the contact angle has a strong influence on the water droplet freezing time. The larger the contact angle is, the longer the freezing time. The frost crystals growth on the droplet surface that frozen on the hydrophobic surface is faster and presents a pattern that is more dendritic than that on the plain copper surface.