The Characterization And Influence Of Ultrasonic Cavitation Intensity In The Sonochemistry Reactor

Along with the progress of science and technology,the ultrasound has been widely applied to ultrasonic cleaning,ultrasonic medicine,sonochemical reaction and ultrasonic sewage treatment et cetera.Ultrasonic cavitation is the main power in practical application for ultrasonic.Since cavitation is the main force accelerating chemical reactions and that sonochemical reactor is the place where chemical reactions were realized,the cavitation intensity in it is directly related to the sonochemical yield.The measurement,characterization and influence study of cavitation intensity is not only the guidance for sonochemical reaction to achieve the best effect,but also an important index to evaluate and optimize sonochemical reaction equipment.However,as for the complexity of ultrasonic cavitation fields and the random spatial and temporal variability,the research of the representation and influence of the ultrasonic cavitation intensity have become an urgent problem to solve.This research plays a guiding role in the application of ultrasound.This paper gives an overview on the sonochemical theory,the effect and influence factors of ultrasonic cavitation phenomenon.After comparing various measurement methods,this paper proposed an improved electrochemical method,combined it with spectrum analysis to measure the intensity of ultrasonic cavitation,and evaluated the combined method by aluminum foils erosion experiment.After evaluating,these methods were used to research the influence of the frequency,shape,the array number and position of the transducer,liquid level on the ultrasonic cavitation intensity.Comparing the 20 kHz,50 kHz and 80 kHz low-frequency ultrasonic cavitation intensity,the results showed that the cavitation intensity reduces as the frequency increases.The intensity at 20 kHz is five times as much as the one at 80 kHz,and the intensity at 50 kHz is three times as much as the one at 80 kHz.Furthermore,synergistic effect of different frequencies on the cavitation could strengthen the cavitation.It is much better than the transducer increment.Then,the ultrasonic cavitation intensity was measured by these methods in regular eight-angular prism and rectangular shape sonochemical reactors.It is observed that the cavitation intensity in the regular eight-angular prism is higher than in the other shape.The conclusion that the more side wall,the less possibility to form standing wave and the less cavitation dead-zone,the more beneficial for ultrasonic cavitation occurring was obtained.Finally,the influence of the array number and position of the transducer on the ultrasonic cavitation fields has been discussed,drawing the conclusion that the cavitation effect when the transducers distribute on the reactor side wall is better than the others on the bottom.We also found the resonance liquid level of the cavitation at different frequencies.The results show that the interval value of the resonance liquid level increases as the frequency decreases.