Research On Coagulation Enhancement Of Submicron Particles With Ultrasonic Technology

Submicron particles on the human respiratory system,the highest penetration efficiency,can cause a variety of respiratory diseases.Submicron particles indoor air pollution is serious,people long time exposure in indoor air pollution poses a serious threat to health.However,its particle size characteristics determine that submicron particles are one of the difficulties in dust removal technology.As a kind of effective pretreatment technology,ultrasonic coagulation technology has great potential and practical application value.In this paper,the experimental method was used to study the coagulation of submicron particles with different particle sizes under different parameters.The ultrasonic wave was used as the sound source,and the submicron particles contained in the real indoor air were selected as the experimental objects.The concentration of number of particles was measured by scanning mobility particle sizers(SMPS).The effects of sound intensity,time of action and ultrasonic frequency on the coagulation effect were studied emphatically.Firstly,the effect of different intensity of sound field on the coagulation of submicron particles was studied in this paper with the particle size range of20.9~805.8nm.The experimental results show that the ultrasonic coagulation efficiency increases with the increase of the intensity of the sound field,and the maximum decay rate of the total concentration can reach 36.1% under 25 kHz ultrasonic wave,the decay rate of the particles with the median diameter from 92 nm to 101 nm and the particle size is 20.9nm up to 47.1%.And then using 25 kHz ultrasonic wave for different action time experiments,the experimental results show that the longer the action time,the higher the particle concentration attenuation rate.When the action time reaches 20 s,the decay rate of the total particle concentration is 42.2%.When the action time increased from 7S to13 s,the attenuation rate of the total number of particles increased rapidly,continue to increase the role of time,the effects of ultrasonic ascension is limited,the total number of particles concentration attenuation increase slow down.The decay rate ofparticles in each particle size is not the same at the same action time,and the overall decay rate decreases with the increase of particle size.Finally,the experimental study on the effect of ultrasonic frequency on the coagulation effect was carried out.The experiment was carried out by using ultrasound at 25 kHz,28kHz and 40 kHz.The experimental results show that the main particle size of three kinds of frequency is 20.9~131nm.The sound pressure level is160.4dB,the total 25 kHz concentration decay rate was up to 36.1%,the highest28 kHz was 34%,the highest 40 kHz was 30%,the sound intensity is 25 kHz the total concentration decay rate as low as 14% 153.4dB,the decay rate of 28 kHz 4% is the lowest,the decay rate of 40 kHz for a minimum of 2%.In the scope of this experimental study,under the condition of low intensity of sound intensity,the effect of high frequency ultrasound is better than that of low frequency.