The Research On The Dynamic Characteristics Of Inhalable Particles And The Effect Of Filtration Efficiency In Sound Field

Inhalable particles from coal combustion and exhaust emission have great effect on both global atmosphere environment and human health,especially for the treatment of particulate pollution which has gradually aroused extensive concern.Acoustic agglomeration as one of the efficient pretreatment method can greatly increase collision probability among particles,then promoting the growth of aggregation in order to improve the removal efficiency of PM2.5 for the traditional particle filtering devices.The effect of acoustic agglomeration under the frequency shifting from 0 to 10000 Hz were studied in this article through the built experimental platform,determining working features under different frequency.The further investigation for acoustic agglomeration of particulate matter was obtained by the agglomeration parameters like sound intensity?the residence time?initial concentration under sound field only and the combined sound field with spray,finding out the changing features of particle size distribution with different experimental parameters.In the process of experiments,the samples of flyash with and without sound field were collected to observe the microstructure by scanning electron microscope(SEM),and from the corresponding results,it proved that the sound field indeed promotes the acoustic agglomeration.At the end of experiments,according to the change of particle concentration measured at the outlet of particle filtering devices in the condition of different acoustic parameters as well as atomization,it can be found that the variation of concentration have certain difference under different conditions.Kernel function model is established based on the orthokinetic mechanism,hydrodynamic interaction and Brownian agglomeration,then calculating collision efficiency between particles in agglomeration volume to correct the total kernel function and simulating the changing tendency of kernel function under different parameters.The group method has been applied to the numerical simulation of the particle size distribution under acoustic field only and the calculated results agree well with the experimental results.More simulations were performed with the sound field only and the combined acoustic field with spray to analyze the changing tendency of particle size distribution and particle concentration along with the change of acoustic parameters?residence time and initial concentration.Finally,the process analysis has been introduced to better know the changing tendency of particle size distribution in different stage,aiming to provide evidences for the prospect of the multi-field cooperation.