Experimental Observation and Analysis of Enhancing Boiling Heat Transfer with Acoustic Cavitation

A series of experiments are carried out to make clear the effects of acoustic cavitation on boiling heat transfer from a 20 mm diameter circular copper tube taking alcohol as working liquid.The cavitation intensity and the distance between the bottom of ultrasonic transducer and the test section are measured in experiments.The experimental research shows that sub-cooled boiling can be enhanced by acoustic cavitation.In the nucleate boiling region,maximum enhancement rate appears in the initiation region of boiling heat transfer,but the enhancement rate decreases with the increase of heat flux.The enhancement rate increases along with the increase of cavitation intensity when heat flux isn't changed.Macroscopic turbulence of the liquid caused by ultrasonic cavitation and decrease of the thickness of boundary layer induced by acoustic shock wave can directly or indirectly influence bubble formation and growth and departure on the wall.