Experimental investigation of the successive freezing processes of water droplets on an ice surface

In the present study, we report for the first time the observations of the successive freezing processes of water droplets on an ice surface. During the experiment, an ice surface was generated first and then kept at a desired temperature by a semi-conductor cooler. After that, three deionized water droplets were deposited onto the ice surface successively and their freezing processes were recorded. The results show that both ice surface temperature and the initial height of the water droplet have significant effects on not only the droplet freezing time, but the contact diameter, angle, and height of the ice bead as well. When the initial height of the water droplet was relatively small, the subsequent water droplet could only cover a portion of the ice bead formed by the previous droplet. Besides, under the same initial height of the water droplet, the decrease of the ice surface temperature could result in an obvious reduction of the contact diameter of the ice bead and an apparent increase of the ice bead angle.