Effect of ultrasonic waveforms on gas–liquid mass transfer in microreactors
Qiang Zhang, Zhengya Dong, Zhikai Liu, Guangwen Chen
Abstract
Abstract This study aims to investigate the effect of ultrasonic waveforms on the gas–liquid mass transfer process. For a given load power ( P ), continuous rectangular wave yielded stronger bubble oscillation and higher mass transfer coefficient ( k L a ) than continuous triangular and sinusoidal wave. For pulsed ultrasound, the k L a decreased monotonically with decreasing duty ratio ( D ), resulting in weak enhancement at low D (≤33%). For a given average load power ( P A ), concentrating the P for a shorter period resulted in a higher k L a due to stronger cavitation behavior. For a given P A and D , decreasing the pulse period ( T ) led to an increase in k L a , which reached a constant high level when the T fell below a critical value. By optimizing the D and T , a k L a equivalent to 92% of that under continuous ultrasound was obtained under pulsed ultrasound at a D of 67%, saving 33% in power consumption.