Experimental Parametric Study of Frequency and Sound Pressure Level on the Acoustic Coagulation and Precipitation of PM2.5 Aerosols

The efficiency of particle removal for PM2.5 aerosols using conventional separation systems is generally low. In this paper, acoustic precipitation and coagulation of aerosols as a preconditioning system is investigated experimentally. The results of experimental study concerning the effect of frequency and sound pressure level (SPL) on the acoustic coagulation and precipitation of PM2.5 aerosols are presented. An acoustic particle conditioning setup was used to perform experiments at the resonance frequencies of 204, 550, 650 and 749 (Hz), and SPLs 140, 150, 155, 162 dB. All experiments were performed under ambient condition and similar initial concentration. The experimental results showed that the effect of acoustics on filtration efficiency is amplified by increasing the frequency and intensity. Eventually, at the frequency of 749 (Hz) and 162 (dB) the acoustic coagulation and precipitation efficiency reaches about 83% which is significant. The results of this study (experimentally and theoretically) prove the existence of a threshold in SPL (>= 155 dB) at which the acoustic precipitation and coagulation efficiency increase rapidly, implying the importance of turbulence coagulation interactions at high intensity acoustic waves. In addition, a new empirical correlation was developed for the acoustic coagulation and precipitation efficiency with reasonable accuracy.