20 KHZ frequency of ultrasonic industry application, already been proved http://www.dowellsonic.com/ that it is the most efficient, and has large-scale application.Ultrasound in liquid medium, by mechanical action, cavitation effect and heat effect, produce mechanical, thermal, optical, electrical, and chemical and ultrasonic dispersion so on a series of effects. Especially high power ultrasonic, can produce strong cavitation, and thus formed in the local instantaneous high temperature, high pressure, vacuum and micro jet.