Effect of ultrasound on the nucleation temperature of water with varied air contents

Abstract

Ultrasonic cavitation is shown to hamper the supercooling required for the nucleation of water. To elucidate the mechanism of nucleation of ice under ultrasonic cavitation, ultrasound waves were applied to supercooled water with oxygen contents of 4.06, 4.48, 4.95, 5.62, and 6.34 mg L−1. Ultrasonic waves were intermittently applied at temperatures below 0 °C. Nucleation temperatures were measured under different experimental conditions. The maximum nucleation temperature (−3.66 ± 0.39 °C) was observed for a water sample containing 4.95 mg L−1 oxygen, at 319 W power (electric power of ultrasound). At 319 W, the intensity of cavitation in this water sample was less than that at higher power. It is concluded that compared with the effect of pressure produced by cavitation, the effect of heat produced by cavitation is significant during the nucleation of water with high-intensity ultrasonic cavitation.