Hydrodynamic cavitation overall intensity evaluation via noise characterization and its effect on phenol oxidative degradation

Abstract

In the present research, noise signals generated by Hydrodynamic cavitation (HC) are charcterized to provide an applicable direct measuring for overall intensity estimation of the phenomenon. The signals amplitude plots as well as spectrogram graph and Fast Fourier Transform (FFT) are used for the characterization of the noise generated by the cavitation phenomenon for each experiment. In order to validate the outcomes, results are complied with the chemical activity. For such a purpose, phenol oxidative degradation kinetics is selected. Experiments are performed at various HC inlet pressure (4–7 bar), operating temperature (20–40 °C) and concentration of H2O2 (0–1000 mg L−1). It was found that the amplitude mean square of the cavitation noise signals could be introduced as a quantitative index for HC overall intensity. The results imply a direct correlation of HC overall intensity with chemical reaction at constant temperature. According to the results, it can also be also concluded that H2O2 presence can affect the intensity of HC and facilitate the super cavitation occurrence, as well as its expected beneficial effect on phenol degradation. The optimum values of the signal characterization and chemical experiments are in the same wavelength showing an 88.9 % degradation in the presence of 1000 mg L−1 H2O2 at 5 bar inlet pressure.

Keywords

• Hydrodynamic cavitation
• Cavitation noise
• Phenol degradation
• Super Cavitation