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Particle air filters used in central residential forced‐air systems are most commonly evaluated for their size‐resolved removal efficiency for particles 0.3‐10 µm using laboratory tests. Little information exists on the removal efficiency of commercially available residential filters for particles smaller than 0.3 µm or for integral measures of mass‐based aerosol concentrations (eg, PM2.5) or total number concentrations (eg, ultrafine particles, or UFPs) that are commonly used in regulatory monitoring and building measurements. Here, we measure the size‐resolved removal efficiency of 50 new commercially available residential HVAC filters installed in a recirculating central air‐handling unit in an unoccupied apartment unit using alternating upstream/downstream measurements with incense and NaCl as particle sources. Size‐resolved removal efficiencies are then used to estimate integral measures of PM2.5 and total UFP removal efficiency for the filters assuming they are challenged by 201 residential indoor particle size distributions (PSDs) gathered from the literature. Total UFP and PM2.5 removal efficiencies generally increased with manufacturer‐reported filter ratings and with filter thickness, albeit with numerous exceptions. PM2.5 removal efficiencies were more influenced by the assumption for indoor PSD than total UFP removal efficiencies. Filters with the same ratings but from different manufacturers often had different removal efficiencies for PM2.5 and total UFPs. 相似文献
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The transportation of ambient particulate matter (PM) from outdoor air into the inlet of a mechanical building ventilation system is poorly understood. No studies have examined the effect commonly used commercial air handling unit (AHU) inlet designs have upon the migration of PM from the ambient environment into the building ventilation system, and implications of this on energy consumption and indoor air quality (IAQ). Through the numerical analysis of commercial AHU inlets, the differences in concentration of PM in ambient air and that within AHUs were determined, more commonly referred to as Aspiration Efficiency (AE %). A 20–50% difference in particle concentrations between ambient air and the in-AHU concentration was observed between forward and rear-facing AHUs relative to ambient wind direction and speed, and at the maximum ventilation flow rate. Furthermore, a decrease in the ventilation flow rates resulted in a significant reduction in PM concentrations entering the rear-facing AHU. Increasing the Stoke number led to lower AE as a continuous decrease was observed for both rear-facing inlets. The findings of this paper show that AHU inlet design has significant implications on IAQ and building energy consumption, and scope exists to design these inlets to impact both aspects positively. 相似文献
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Electret filters are widely used in HVAC systems to decrease particulate matter in indoor environments. The previous standard in Europe for testing air filters for general ventilation was EN 779. In July 2018, it was replaced by the new international standard ISO 16890. One major change is the discharging process: It is now performed by treating the filters with saturated isopropyl alcohol (IPA) vapor. The process is intended to simulate a worst-case scenario of the filtration efficiency due to the reduction of the electret effect. These minimal efficiencies are a principal part of the filter classification. Therefore, two round robin tests with different filter classes (F9 and F7 according to EN 779) and up to eleven participants were carried out to evaluate the new test method by comparing the filtration efficiencies and pressure drops before and after the IPA treatment. Pressure drop measurements showed no mechanical altering of the material due to the discharging process. The calculated filter classes had a maximum deviation of 5%. Even with different equipment, the results indicate that the new ISO 16890 seems to be a viable test standard and a decent replacement for previous national standards. 相似文献
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对燃烧过程超细颗粒物的国内外研究现状进行了综述,介绍了国内外近期开展的有关超细颗粒物的研究课题、研究方向,简述了常用的超细颗粒物的采样和分析方法,并对其研究的发展趋势进行了预测,由此提出了目前应该开展研究的重点和方向。 相似文献
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袋式除尘机组性能测试及分析 总被引：2，自引：0，他引：2
本文针对PL型袋式除尘机组进行技术性能测试及分析,得出了除尘机组风量及滤袋阻力随发尘量变化关系回归关联式。测试结果表明：该除尘机组性能参数达到铭牌标定参数,是一种性能较好的袋式除尘设备;在实际运行中,除尘机组残留压力损失并不停留在某一恒定值,而是一次循环比一次循环残留压力损失增加,减少残留压力损失是延长布袋使用寿命的关键;并针对除尘机组存在的问题进行了分析。 相似文献
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Application of fractal flocculation and vertical transport model to aquatic sol-sediment systems 总被引：1，自引：0，他引：1
In estuarine and coastal environments, flocculation occurs between particles of different fractal dimensions and of different densities. Questions remain concerning the level of detail required to model particle flocculation and settling in these heterogeneous systems. This paper compares the goodness of fit between two flocculation models, using measured time series particle size distribution data collected from clay, colloidal silica, emulsified crude oil, clay-crude oil, and silica-crude oil systems. The coalesced sphere (CS) flocculation model includes the effects of heterogeneous particle size and density; the modified coalesced fractal sphere (mCFS) model adds effects due to heterogeneous fractal dimension. Goodness of fit was quantified using values of a minimized objective function, the mean of the sum of the square of the relative residuals (MSSRR). For nearly all tested experimental conditions, MSSRR values varied less than 5% between the CS and mCFS flocculation models. Additionally, collision efficiency values for single-particle-type (alpha(HOMOO)) and dual-particle-type (alpha(HETT)) systems were obtained through parameter regression using the CS and mCFS models. Using the mCFS model, estimated fractal dimension (D) values obtained for clay and clay-oil systems were between 2.6 and 3.0, lower than that postulated by the CS model but higher than that estimated experimentally by the particle concentration technique. The Stokes settling velocity of a clay aggregate of a given mass is reduced with decreased fractal dimension. This results in clay-oil flocculation occurring faster than floc sedimentation in the studied hydrodynamic range. Thus, the mCFS model provides insights to the fate of spilled oil in inland and coastal waters. 相似文献
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针对人造毛皮行业存在短纤维和细小尘杂难处理的特点,设计一套新型环吹袋式除尘器,对其性能进行试验研究,分别考察了关闭和开启环吹时过滤速度对过滤压力损失和过滤效率的影响以及清灰周期的确定。结果表明压力损失随过滤速度的增大而增大,过滤效率随着过滤速度的增大呈现先减小后增大的规律。在保证除尘器阻力的前提下,降低过滤速度,开启环吹,有利于清灰周期的延长。 相似文献
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本文阐明了对袋式除尘器用滤料进行表面技术处理的必要性及其产生的相关问题,并通过现有理论及实验研究结果对滤料孔隙率与过滤阻力、过滤效率之间的两组关系分别进行分析论证,得出两组关系在除尘实践中存在的矛盾:滤料的孔隙率增大,过滤阻力减小,但是过滤效率也随之减小;而当孔隙率减小时,过滤效率增大,过滤阻力也增大。在实际过滤除尘工程中,用户和设计者往往希望拥有高效低阻的过滤材料。为此本文给出了解决这个矛盾的思路,以及依据实际过滤除尘工况寻找复合滤料最佳孔隙率的具体操作方法,这不仅对滤料的性能优化设计、选择提供了方法指导,还将有助于新型滤料的研发,同时也避免了对滤料进行表面处理时存在的盲目性。 相似文献
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从质量平衡关系式得出纤维过滤器过滤固体气溶胶的非稳态过程第一阶段中穿透率和积尘量的关系式,并用无量纲参数加以简化。R.C.Brown和D.A.Japuntich的实验数据验证了该关系式的可靠性。结合R.C.Brown的数据分析得到同一时间穿透率随厚度增加而减小,同一位置处穿透率随时间而减小;同一时间局部当量积尘量随厚度增加而减小,同一位置处局部当量积尘量随时间而增加;当量总积尘量与无量纲时间呈线性关系。 相似文献
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陶粒生物滤池与无烟煤滤池强化过滤效果对比 总被引：1，自引：0，他引：1
以北京某自来水厂处理密云水库蓄水的出水（混凝沉后水）为试验用水，通过中试对比研究了陶粒生物滤池与无烟煤滤池的过滤效果。结果表明，陶粒生物滤池与无烟煤滤池对水中颗粒物的去除效果接近；对于水中的浊度，无烟煤滤层对其去除效果较好，而陶粒滤层的过滤效果则较差，需要依靠石英砂的截污作用来降低浊度；陶粒对有机物的过滤效果优于无烟煤的，陶粒生物滤池对TOC的去除率为14．9％～30．2％，对CODMn的去除率为13．1％～38．5％；与无烟煤滤池相比，陶粒生物滤池具有水头损失增长快、周期较短、初滤水中颗粒物较多等缺点。 相似文献
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Cattaneo A Peruzzo C Garramone G Urso P Ruggeri R Carrer P Cavallo DM 《Indoor air》2011,21(6):489-500
The province of Lodi is located in northern Italy on the Po River plain, where high background levels of air pollutants are prevalent. Lodi province is characterized by intensive agriculture, notably animal husbandry. This paper assesses indoor levels of selected airborne pollutants in 60 homes in the province, with special attention to size-fractionated particulate matter (PM). Indoor PM?.? concentrations are frequently higher than current guidelines. PM?? and nitrogen dioxide also exceed the respective guideline recommendations in some cases, noting that 24-h nitrogen dioxide levels were compared with an annual limit value. All other studied pollutant levels are below current international guidelines. Among indoor PM size fractions, PM?.? is predominant in terms of mass concentrations corresponding to 57% of PM?? in summer and 71% in winter. A strong seasonal trend is observed for all studied pollutants, with higher levels in winter corresponding to changes in ambient concentrations. The seasonal variation in PM?? is largely due to PM?.? increase from summer to winter. Summer indoor PM levels are mainly from indoor-generated particles, while particles of outdoor origin represent the main contribution to winter indoor PM levels. On average, indoor concentrations of coarse PM are mostly constituted by indoor-generated particles. PRACTICAL IMPLICATIONS: This study presents a comparison between measured indoor concentrations in the study area and indoor air quality guideline criteria. Accordingly, particulate matter (PM) and NO? are identified as key pollutants that may pose health concerns. It is also found that indoor PM in residential units is mainly constituted by particles with aerodynamic diameters <0.5 μm, especially in winter. Risk mitigation strategies should be focused on the reduction in indoor levels of NO? and ultrafine and fine particles, both infiltrated from outdoors and generated by indoor sources. 相似文献
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Yutong Zhu Xiaoming Song Rongshan Wu Jiakun Fang Lingyan Liu Tong Wang Shuo Liu Hongbing Xu Wei Huang 《Indoor air》2021,31(6):1707-1721
Improving air quality in indoor environments where people live is of importance to protect human health. In this systematic review, we assessed the effectiveness of personal-level use of air filtration units in reducing indoor particulate matters (PM) concentrations under real-world situations following systematic review guidelines. A total of 54 articles were included in the review, in which 20 randomized controlled/crossover trials that reported the changes in indoor fine PM (PM2.5) concentrations were quantitatively assessed in meta-analysis. Standardized mean differences (SMDs) were calculated for changes in indoor PM concentrations following air filtration interventions. Moderate-to-large reductions of 11%–82% in indoor PM2.5 concentrations were observed with SMD of −1.19 (95% CI: −1.50, −0.88). The reductions in indoor PM concentrations varied by geographical locations, filtration technology employed, indoor environmental characteristics, and air pollution sources. Most studies were graded with low-to-moderate risk of bias; however, the overall certainty of evidence for indoor PM concentration reductions was graded at very low level. Considering the effectiveness of indoor air filtration under practical uses, socio-economic disparities across study populations, and costs of air filter replacement over time, our results highlight the importance of reducing air pollution exposure at the sources. 相似文献
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The ability to adjust the properties of the filter medium by altering the degree of the medium compression is important because the different porosities in media affect the ideal filter performance according to the properties of influent wastewater. This study therefore focused on the particle size distribution (PSD) of compressible media filter (CMF) effluents depending on the compression ratio (0–30%) and the filter bed depth (Layers 1–5) in order to evaluate the CMF performance. The results showed that the removal efficiency for particles larger than 10 µm was more than 90% while that for particles smaller than 10 µm was less than 85% of removal efficiency. From the power law fit, substantial decreases in the number of large‐sized particles were observed in the PSD. Particle removal efficiencies increased along with the average compression ratio increase. Furthermore, the results demonstrated that each layer in the bed had a different role in the filter performance, and it was found that a filter bed of about 0.45–0.60 m would be needed for the production of the desired effluent quality in this study. The detachment phenomenon was observed in particles larger than 5 µm, especially in 5–15 µm particles. 相似文献
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现代城市规划的缘起与公共健康关系密切,20世纪初期作为政府对于公共卫生的干预途径和方法出现。目前欧美对于健康城市规划的研究关注如何通过规划设计,减少特定疾病的患病率,国内相关研究开始起步。由于我国城市大气环境问题日益严峻,雾霾(PM2.5,PM10等颗粒物)频发,导致呼吸系统疾病患病人数上升;非常有必要探究如何通过建成环境要素的规划和设计优化,减缓颗粒物对于居民呼吸系统健康的影响。本文基于颗粒物分布、呼吸系统疾病、城市空间要素三者关系的文献研究,以建成环境要素是否影响颗粒物浓度分布作为自变量选取原则,以人口、社会和经济因素作为协变量,以呼吸系统疾病(特别是肺癌)的个体病患分布和特定空间单元患病率作为因变量,建构在颗粒物分布视角下的健康城市规划理论框架,并提出构建实证模型的方法和路径。 相似文献
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L. Morawska A. Afshari G. N. Bae G. Buonanno C. Y. H. Chao O. Hänninen W. Hofmann C. Isaxon E. R. Jayaratne P. Pasanen T. Salthammer M. Waring A. Wierzbicka 《Indoor air》2013,23(6):462-487
Motivated by growing considerations of the scale, severity, and risks associated with human exposure to indoor particulate matter, this work reviewed existing literature to: (i) identify state‐of‐the‐art experimental techniques used for personal exposure assessment; (ii) compare exposure levels reported for domestic/school settings in different countries (excluding exposure to environmental tobacco smoke and particulate matter from biomass cooking in developing countries); (iii) assess the contribution of outdoor background vs indoor sources to personal exposure; and (iv) examine scientific understanding of the risks posed by personal exposure to indoor aerosols. Limited studies assessing integrated daily residential exposure to just one particle size fraction, ultrafine particles, show that the contribution of indoor sources ranged from 19% to 76%. This indicates a strong dependence on resident activities, source events and site specificity, and highlights the importance of indoor sources for total personal exposure. Further, it was assessed that 10–30% of the total burden of disease from particulate matter exposure was due to indoor‐generated particles, signifying that indoor environments are likely to be a dominant environmental factor affecting human health. However, due to challenges associated with conducting epidemiological assessments, the role of indoor‐generated particles has not been fully acknowledged, and improved exposure/risk assessment methods are still needed, together with a serious focus on exposure control. 相似文献