室内超细微粒渗透传输机理研究
发布时间：2018-08-30 20:08
【摘要】：在室内无明显污染源的情况下,室外颗粒物的渗透是室内颗粒物的主要来源。为了评估室内人体污染物暴露风险,有必要了解颗粒渗透过程的影响因素及传输机理。本文采用实验方法和数值模拟方法研究室外颗粒物通过建筑狭缝渗透进入室内的传输机理及其影响因素,并对狭缝内污染物扩散规律给予阐述。实验设计搭建不同尺寸狭缝的测量装置平台,借助快速粒径谱仪(FMPS)和质量浓度采样分析仪(DustTrak)测量两实验舱内的颗粒数浓度和质量浓度变化,得到不同粒径颗粒的穿透率和粒径谱演变特征。研究显示,在仪器粒径测量范围6～523nm内,随着粒径的增加,穿透率呈增加趋势,其主导影响因素为布朗扩散运动。在狭缝压差为4Pa,缝高为1mm,缝长为43mm的情况下,平均穿透率变化范围为0.51～0.98,而在缝长为94mm时,平均穿透率变化范围在0.55～0.95之间,颗粒穿透率随着缝长增加和压差减小而减小。室内外颗粒数浓度呈线性相关性,其室内外数浓度比值(I/O)为0.69～0.74,相关系数R2均大于0.99,表明室内颗粒物浓度很大程度上与室外颗粒的渗透有关。室内外颗粒质量浓度平均比值为0.74,相关系数R2达0.98以上。室外颗粒PM1、PM2.5、PM10和总颗粒质量浓度与穿透率呈负相关性。数值模拟方法采用Fluent软件进行计算,考虑其沉降机制如布朗扩散、重力沉降以及Saffman升力的影响。数值模拟显示,狭缝缝长越长,压差越小,缝高越小,颗粒穿透率就越小,其中缝高占主导影响因素。当缝高变化时,同一个粒径的颗粒沉降到壁面的主导因素变化,穿透率也随之变化。小粒径颗粒布朗扩散占主导作用,随着粒径的增大,重力沉降所占比率增加。在不同形状管道中,粒径较大的颗粒更容易沉积在入口段管道,因此入口段颗粒浓度最高。粒径较小的颗粒随气流运动。通道拐角越多,颗粒沉积位置越分散,从而减小通道阻塞。L型管道和U型管道在拐角底部及管道右壁面颗粒浓度较高,由于拐角处存在漩涡,颗粒更容易沉积下来。
[Abstract]:The permeation of indoor particulate matter is the main source of indoor particulate matter without obvious indoor pollution sources. In order to evaluate the exposure risk of indoor human pollutants, it is necessary to understand the influencing factors and transport mechanism of particle permeation process. In this paper, experimental method and numerical simulation method are used to study the transport mechanism and influencing factors of indoor permeation of outdoor particulates through the building slit, and the diffusion law of pollutants in the slit is expounded. A platform for measuring slit with different sizes was designed and built. The change of particle number and mass concentration in the two experimental cabins was measured by (FMPS) and (DustTrak). The characteristics of penetration rate and particle size spectrum evolution of different particle size were obtained. The results show that the penetration rate increases with the increase of particle size in 6~523nm, and the dominant factor is Brownian diffusion movement. When the slit pressure difference is 4 Pa, the seam height is 1 mm, and the seam length is 43mm, the average penetration rate varies from 0.51g to 0.98, while when the slit length is 94mm, the average penetration rate ranges from 0.550.95 to 0.550.95. The particle penetration rate decreases with the increase of the slit length and the decrease of the pressure difference. The concentration of indoor and outdoor particles was linearly correlated with the ratio of indoor and outdoor particle concentration (I / O) was 0.69 ~ 0.74, and the correlation coefficient R ~ (2) was higher than 0.99, indicating that indoor particle concentration was related to the permeation of outdoor particles to a great extent. The average mass concentration ratio of indoor and outdoor particles is 0.74, and the correlation coefficient R ~ 2 is above 0.98. There was a negative correlation between outdoor particle PM1,PM2.5,PM10 and total particle mass concentration and penetration rate. The numerical simulation method is calculated by Fluent software, considering the influence of the settlement mechanism such as Brownian diffusion, gravity settlement and Saffman lift. Numerical simulation shows that the longer the slit is, the smaller the pressure difference is, the smaller the seam height is, and the smaller the particle penetration rate is, and the higher the slit height is, the more the influence factor is. When the seam height changes, the dominant factor of settling to the wall of the same particle size changes, and the penetration rate also changes. The Brownian diffusion of small particle size plays a dominant role, and the ratio of gravity deposition increases with the increase of particle size. In the pipeline with different shapes, the larger particle size is easier to deposit in the inlet pipe, so the particle concentration in the inlet section is the highest. The smaller particles move with the air flow. The more the channel corner, the more dispersed the particle deposition position, thus reducing the channel blocking. L-type pipeline and U-shaped pipeline in the corner bottom and the right wall of the pipe particle concentration is higher, because of the swirl around the corner, particles are easier to deposit down.
【学位授予单位】：中国计量学院
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X51
本文编号：2214154
[Abstract]:The permeation of indoor particulate matter is the main source of indoor particulate matter without obvious indoor pollution sources. In order to evaluate the exposure risk of indoor human pollutants, it is necessary to understand the influencing factors and transport mechanism of particle permeation process. In this paper, experimental method and numerical simulation method are used to study the transport mechanism and influencing factors of indoor permeation of outdoor particulates through the building slit, and the diffusion law of pollutants in the slit is expounded. A platform for measuring slit with different sizes was designed and built. The change of particle number and mass concentration in the two experimental cabins was measured by (FMPS) and (DustTrak). The characteristics of penetration rate and particle size spectrum evolution of different particle size were obtained. The results show that the penetration rate increases with the increase of particle size in 6~523nm, and the dominant factor is Brownian diffusion movement. When the slit pressure difference is 4 Pa, the seam height is 1 mm, and the seam length is 43mm, the average penetration rate varies from 0.51g to 0.98, while when the slit length is 94mm, the average penetration rate ranges from 0.550.95 to 0.550.95. The particle penetration rate decreases with the increase of the slit length and the decrease of the pressure difference. The concentration of indoor and outdoor particles was linearly correlated with the ratio of indoor and outdoor particle concentration (I / O) was 0.69 ~ 0.74, and the correlation coefficient R ~ (2) was higher than 0.99, indicating that indoor particle concentration was related to the permeation of outdoor particles to a great extent. The average mass concentration ratio of indoor and outdoor particles is 0.74, and the correlation coefficient R ~ 2 is above 0.98. There was a negative correlation between outdoor particle PM1,PM2.5,PM10 and total particle mass concentration and penetration rate. The numerical simulation method is calculated by Fluent software, considering the influence of the settlement mechanism such as Brownian diffusion, gravity settlement and Saffman lift. Numerical simulation shows that the longer the slit is, the smaller the pressure difference is, the smaller the seam height is, and the smaller the particle penetration rate is, and the higher the slit height is, the more the influence factor is. When the seam height changes, the dominant factor of settling to the wall of the same particle size changes, and the penetration rate also changes. The Brownian diffusion of small particle size plays a dominant role, and the ratio of gravity deposition increases with the increase of particle size. In the pipeline with different shapes, the larger particle size is easier to deposit in the inlet pipe, so the particle concentration in the inlet section is the highest. The smaller particles move with the air flow. The more the channel corner, the more dispersed the particle deposition position, thus reducing the channel blocking. L-type pipeline and U-shaped pipeline in the corner bottom and the right wall of the pipe particle concentration is higher, because of the swirl around the corner, particles are easier to deposit down.
【学位授予单位】：中国计量学院
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X51
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