Sonochemical production of hydrogen: Enhancement by summed harmonics excitation

A particular case of harmonics excitation using ultrasonic waves with the frequencies of 200, 300 and 500 kHz at an acoustic amplitude of 2 atm is numerically investigated in the present paper, as a new method aiming to improve the sonochemical production of hydrogen within active cavitation bubble. The modification of the conventional sine signal, travelling across an aqueous medium saturated with oxygen, into evolutionary number of harmonics tending to square signal proved to be of a notable efficiency regarding the hydrogen emergence kinetics. The productivity was revealed to be the highest under 200 kHz, while the gain due to the use of a sum of six successive harmonics instead of sine wave was the most important under 500 kHz. Moreover, the sum of six harmonics proved to be more efficient than the square wave in terms of hydrogen production.