气溶胶颗粒在风管系统中沉降的实验研究

气溶胶颗粒是室内外空气中存在的一类重要污染物。为了研究气溶胶颗粒在风管系统中分布和沉降的规律,本文以滑石粉为代表,通过在接近实际工程的矩形镀锌钢板风管系统中释放气溶胶颗粒对其在风管系统中的沉降进行了初步实验研究。实验在不同风速下共进行了两次,并主要在风管系统中的水平直段和局部构件处测量了滑石粉的沉降量。根据滑石粉的沉降量计算出滑石粉的沉降速度,并且对比和分析了不同风速下,风管系统中不同位置的滑石粉的沉降速度。实验表明,气溶胶颗粒在水平直段的底面上的沉降速度最大,侧面上的其次,顶面上的最小;并且气溶胶颗粒的沉降速度随着风速的减小而减小。根据实验数据,分析了影响气溶胶颗粒沉降速的主要因素,包括:风速、沉降面的朝向、局部构件的形状、管道漏风。

Experimental Study on Deposition of Aerosol Particles in Ductwork

Aerosol particles are an important kind of indoor and outdoor main pollutants and its exposure is detrimental to human health.Laboratory experiments were conducted to study preliminarily on deposition of aerosol particles in ventilation duct systems.Particle deposition experiments were conducted with french chalk released in rectangular ductwork,which approximate to ventilation ducts using real HVAC materials.These ducts were fabricated from galvanised steel.Experiments were conducted twice at different air speeds.There were three test ducts in ductwork.Test duct 1 was the sections of connector and test ducts 2,3 are the straight horizontal sections of the experimental duct.Particle deposition fluxes to four panels at each of the floor,wall and ceiling surfaces of test ducts 1,2 and 3 were measured in each experiment.Particle deposition velocities were calculated from the particle flux to the surface and the airborne particle concentration in the duct.Deposition velocities of aerosol particles on the different location were contrasted and analyzed at different air speeds.In straight horizontal sections of the experimental duct,experiments showed deposition velocities of aerosol particles to be highest at duct floors,intermediate at duct walls,and lowest at duct ceilings.Deposition velocities to duct ceiling,wall and floor surfaces decreased with a decrease in air speed.On the basis of experiment data,the major factors influencing particle deposition rates are the air speed,the orientation of the deposition surface,size of the duct and the local air leak.