Droplet cooling and freezing characteristic in effect of ultrasonic

摘要

The application of ultrasound to liquid freezing draws growing attention in these years and its potential seems very promising. In order to make clear droplet cooling and freezing assisted by ultrasonic, numerical simulation of droplet cooling and freezing by ultrasonic has been performed by solidification/melting model of Fluent. Variation of droplet temperature distribution, droplet freezing radius and solid-liquid proportion of droplet in process of freezing are analyzed in different ultrasonic intensities(200W/m(2), 400W/m(2) and 800W/m(2)) and ultrasonic frequency (20,000Hz, 40,000Hz and 80,000Hz) to reflect the effect of ultrasonic on cooling and freezing of droplet. The related experiment is carried out to obtain the droplet freezing state and temperature variation in the effect of ultrasound. The results are shown that the lower ultrasonic frequency would cause droplet to be cooled and freeze easily, and smaller droplet radius is favorable to droplet freezing. Besides, the lower environmental temperature and the greater air velocity would reduce freezing time.