Measurement Of Particle Resuspension From Surfaces When Swept By A Hairbrush

One important factor that affects indoor air quality is the suspended particles,which may come from indoor pollutant sources or outdoors.For indoor pollutant sources,re-suspension of the deposit particulate is a primary constituent,for it contributes 30 percent of indoor PM10 according to studies.Re-suspended particles can be caused by daily activities such as walking,dancing or sweeping.However,current articles concentrate on resuspension of particles caused by walking and dancing.There are few studies addressed on the effects of sweepings,especially the influence of each sweeping parameter.Since sweeping is an indispensable daily behavior,exploring its influence on particle resuspension is important and necessary.This study investigates the influence of sweeping behavior by hairbrush on particle resuspension by experiment,including the bristle diameter,bristle dispersity,sweeping penetration and sweeping speed.To avoid the interference of outside suspended particles,a clean wind tunnel was built.In it,a particle-laden plate obtained by naturally depositing the standard Arizona dusts was swept by an electric controlled hairbrush.To well observe the turbulent flow rose by sweeping,the smoke was used as tracer gas.During the sweeping process,with a light surface generated by laser generator as background,a high speed camera was used to capture the particle accumulation on the surface,separation and re-suspension from surface and particle clouds' movement in the air.A precision balance was used to calculate the removal quantity on the particle-laden plate,and a particle counter was used to record the number of resuspension particles.After the experiment,the distribution of re-deposit particle on the surface was also saved by camera.The results show that the movement of resuspension particles caused by sweeping is along the tangent of the brush rotation and the forehand of particle-laden surface.Some large suspended particle clusters will rapidly re-deposited on the surface again.With the increase of the bristle's diameter and the decrease of the bristle's dispersity,both the resuspension particles and removal quantity increase,and the large diameter bristles can promote resuspension of small particles.With the increase of the sweeping depth,the resuspension particles and removal quantity also increase and the growth rate become faster,for it enhances the elastic force and broadens the clean areas.Moreover,with the increase of sweeping speed in a certain range,the resuspension particles and removal quantity increase as well,for it enhances the inertial oscillation of the bristle after the bristles leave surface.