Ultrasonic Vibration for Instantaneously Removing Frozen Water Droplets from Cold Vertical Surface

摘要

An experimental study concerning frozen water droplets adhered to cold surface subjected to 20 kHz ultrasonic vibration was conducted. The transient process of frozen water droplet shedding from cold surface was recorded and the simultaneous internal temperature variation of cold plate was measured. In addition, the mechanism of ultrasonic vibration for removing frozen water droplets from cold surface was qualitatively analyzed. It is found that the frozen water droplets instantaneously fall off from the vertical surface accompanying with flick phenomenon due to the combined action of interface transverse shear force induced by ultrasonic mechanical effect and impact force generated by ultrasonic cavitation. Meanwhile, an instantaneous internal temperature jump of cold flat occurs. The results indicated that the high frequency ultrasonic vibration can effectively remove the frozen water droplets adhered to cold surface which is the base for frost growth and thus it is a highly effective defrosting method.