濕度對室內(nèi)顆粒物分布的影響
發(fā)布時間：2018-11-06 19:38
【摘要】：顆粒物作為室內(nèi)空氣中的主要污染物之一，其在室內(nèi)的分布情況對室內(nèi)空氣品質(zhì)至關(guān)重要。雖然目前國內(nèi)外對室內(nèi)顆粒物分布進行了大量研究，但濕度對室內(nèi)顆粒物分布的影響仍不明確，本文主要通過完成以下幾方面工作對其進行了初步研究： （1）簡單介紹了室內(nèi)顆粒物來源、粒徑范圍、濃度影響因素和對人體健康的危害后，又從理論研究、數(shù)值模擬和實驗研究三方面闡述了室內(nèi)顆粒物運動分布的國內(nèi)外研究現(xiàn)狀，總結(jié)出目前對室內(nèi)顆粒物分布的研究均未考慮相對濕度的影響。 （2）分析了單個顆粒在流場中受到的作用力，給出了顆粒輸運方程、輸運通量。計算了顆粒間的氣體動力學碰撞及碰撞后導致凝并的相關(guān)作用力，得出相對濕度較大時，液橋力是顆粒物間凝并的主導作用力。 （3）實驗研究方面，為了排除溫度變化對實驗結(jié)果的影響和對比分析不同濕度條件下室內(nèi)顆粒物分布的不同，在實驗房間內(nèi)建立了恒溫恒濕控制系統(tǒng)，并通過調(diào)濕設(shè)置了幾種相對濕度不同的工況。利用掃描電鏡微觀觀察了顆粒源釋放的顆粒、本底濃度及不同濕度條件下室內(nèi)顆粒物的微觀形態(tài)，發(fā)現(xiàn)只有相對濕度為65%以上的兩種工況下，顆粒物之間才發(fā)生明顯的凝并現(xiàn)象，不同粒徑不同形態(tài)的小顆粒凝并生成不同粒徑不同形態(tài)的大顆粒，且相對濕度越大，凝并現(xiàn)象越顯著。利用粉塵檢測儀、光學顆粒物粒徑譜儀測試分析了不同工況下室內(nèi)顆粒物的質(zhì)量濃度、數(shù)密度和粒徑分布，發(fā)現(xiàn)與其他工況相比相對濕度為80%時，室內(nèi)顆粒物的質(zhì)量濃度的衰減速度最小、0.3~2μm粒徑范圍內(nèi)的顆粒物數(shù)密度衰減速度最小、0.3~1.5μm粒徑范圍內(nèi)的顆粒物占總顆粒物百分比變化幅度也最小。最后對相對濕度為80%時，顆粒物質(zhì)量濃度、數(shù)密度和粒徑分布隨時間變化曲線發(fā)生跳躍時的臨界相對濕度值進行了研究。每種工況下的各項實驗均進行了實驗一和重復實驗兩次實驗，結(jié)果表明實驗的可重復性較好。 （4）通過CFD方法，利用fluent模擬了工況1（RH=35%）下室內(nèi)顆粒物的運動分布，對比實驗數(shù)據(jù)說明了數(shù)值模擬的正確性，分析了室內(nèi)流場和顆粒物質(zhì)量濃度分布及其隨時間變化情況。 總的來說，相對濕度增大會改變顆粒物碰撞凝并的主要作用力，增強凝并效果，，使得更多的小顆粒凝并生成大顆粒，改變室內(nèi)顆粒物的質(zhì)量濃度、數(shù)密度和粒徑分布，進而對室內(nèi)顆粒物的分布造成影響。
[Abstract]:As one of the main pollutants in indoor air, the distribution of particulate matter in indoor air is very important to indoor air quality. Although much research has been done on indoor particulate matter distribution at home and abroad, the effect of humidity on indoor particulate matter distribution is still unclear. In this paper, a preliminary study was carried out in the following aspects: (1) after a brief introduction of indoor particulate matter sources, particle size range, factors affecting concentration and harm to human health, the theoretical study was carried out. In this paper, the present research situation of indoor particle movement distribution is described in terms of numerical simulation and experimental study, and it is concluded that the influence of relative humidity is not considered in the research of indoor particulate matter distribution at present. (2) the acting force of a single particle in the flow field is analyzed, and the particle transport equation and transport flux are given. The gas-dynamic collision between particles and the related forces leading to condensation after collision are calculated. It is concluded that the liquid bridge force is the leading force of coagulation between particles when the relative humidity is relatively high. (3) in order to eliminate the influence of temperature change on the experimental results and to compare and analyze the distribution of indoor particulate matter under different humidity conditions, a constant temperature and humidity control system was established in the experimental room. Several different working conditions of relative humidity are set up through humidification. The microscopic morphology of particles released from particle source, background concentration and different humidity were observed by scanning electron microscope. It was found that there were only two working conditions where the relative humidity was more than 65%. The phenomenon of coagulation and coalescence occurred only between particles. The smaller particles with different particle sizes and different shapes were coagulated, and the larger the relative humidity was, the more obvious the coagulation phenomenon was. Using dust detector and optical particle size spectrometer, the mass concentration, number density and particle size distribution of indoor particles under different working conditions were measured and analyzed. It was found that the relative humidity was 80 when compared with other working conditions. The attenuation rate of mass concentration of indoor particles was the smallest, the attenuation rate of particle number density was the least in the range of 0.3 渭 m and 1.5 渭 m, and the change range of particle percentage in the range of 0.3 渭 m and 1.5 渭 m was the smallest. At last, the critical relative humidity values of particle mass concentration, number density and particle size distribution when the relative humidity is 80 are studied when the curve of variation of particle mass density and particle size changes with time. Experiment 1 and repeated experiment were carried out under each working condition, and the results showed that the experiment was reproducible. (4) the movement distribution of indoor particulate matter under working condition 1 (RH=35%) was simulated by fluent by CFD method. The correctness of numerical simulation was proved by comparing the experimental data. The indoor flow field and particle mass concentration distribution and their variation with time were analyzed. In general, the increase of relative humidity will change the main force of particle collision condensation, enhance the coagulation effect, make more small particles coagulate and produce large particles, and change the mass concentration, number density and particle size distribution of indoor particles. Then the distribution of indoor particulate matter is affected.
【學位授予單位】：湖南工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2013
【分類號】：X513;TU834.8
本文編號：2315263
[Abstract]:As one of the main pollutants in indoor air, the distribution of particulate matter in indoor air is very important to indoor air quality. Although much research has been done on indoor particulate matter distribution at home and abroad, the effect of humidity on indoor particulate matter distribution is still unclear. In this paper, a preliminary study was carried out in the following aspects: (1) after a brief introduction of indoor particulate matter sources, particle size range, factors affecting concentration and harm to human health, the theoretical study was carried out. In this paper, the present research situation of indoor particle movement distribution is described in terms of numerical simulation and experimental study, and it is concluded that the influence of relative humidity is not considered in the research of indoor particulate matter distribution at present. (2) the acting force of a single particle in the flow field is analyzed, and the particle transport equation and transport flux are given. The gas-dynamic collision between particles and the related forces leading to condensation after collision are calculated. It is concluded that the liquid bridge force is the leading force of coagulation between particles when the relative humidity is relatively high. (3) in order to eliminate the influence of temperature change on the experimental results and to compare and analyze the distribution of indoor particulate matter under different humidity conditions, a constant temperature and humidity control system was established in the experimental room. Several different working conditions of relative humidity are set up through humidification. The microscopic morphology of particles released from particle source, background concentration and different humidity were observed by scanning electron microscope. It was found that there were only two working conditions where the relative humidity was more than 65%. The phenomenon of coagulation and coalescence occurred only between particles. The smaller particles with different particle sizes and different shapes were coagulated, and the larger the relative humidity was, the more obvious the coagulation phenomenon was. Using dust detector and optical particle size spectrometer, the mass concentration, number density and particle size distribution of indoor particles under different working conditions were measured and analyzed. It was found that the relative humidity was 80 when compared with other working conditions. The attenuation rate of mass concentration of indoor particles was the smallest, the attenuation rate of particle number density was the least in the range of 0.3 渭 m and 1.5 渭 m, and the change range of particle percentage in the range of 0.3 渭 m and 1.5 渭 m was the smallest. At last, the critical relative humidity values of particle mass concentration, number density and particle size distribution when the relative humidity is 80 are studied when the curve of variation of particle mass density and particle size changes with time. Experiment 1 and repeated experiment were carried out under each working condition, and the results showed that the experiment was reproducible. (4) the movement distribution of indoor particulate matter under working condition 1 (RH=35%) was simulated by fluent by CFD method. The correctness of numerical simulation was proved by comparing the experimental data. The indoor flow field and particle mass concentration distribution and their variation with time were analyzed. In general, the increase of relative humidity will change the main force of particle collision condensation, enhance the coagulation effect, make more small particles coagulate and produce large particles, and change the mass concentration, number density and particle size distribution of indoor particles. Then the distribution of indoor particulate matter is affected.
【學位授予單位】：湖南工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2013
【分類號】：X513;TU834.8
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