Blower-door estimates of PM2.5 deposition rates and penetration factors in an idealized room

2020 ◽  
pp. 1420326X2094442 ◽  
Author(s):  
Yonghang Lai ◽  
Ian Ridley ◽  
Peter Brimblecombe
Keyword(s):  
Deposition Rate ◽  
Coefficient Of Variation ◽  
Particle Deposition ◽  
Experimental Methods ◽  
Test Cell ◽  
Deposition Rates ◽  
Penetration Factor ◽  
Surface Materials ◽  
Novel Method ◽  
Indoor And Outdoor

Particle deposition and penetration in buildings has been widely studied, but the effect of indoor characteristics merits further investigation, so improved experimental methods may be needed. The present study measured indoor and outdoor concentrations of PM2.5 and estimated PM2.5 deposition rates and penetration factors under a variety of different indoor situations, with a novel method (blower-door method). The blower-door method is compared with the standard decay and rebound method for an idealized room (a portable building test cell; 6.08 m [Formula: see text] 2.40 m [Formula: see text] 2.60 m) under eight testing scenarios (empty, cardboard boxes in three arrangements, terry cloth wall covering, and three sets of window holes); run three times to establish the coefficient of variation representing precision. Results show that higher induced indoor–outdoor pressure differences cause a larger variation of estimated effective deposition rate on different indoor surfaces. The deposition rate and penetration factor may be influenced by indoor surface materials. The blower-door method gives higher precision for the estimates, and detects subtle differences in penetration factors, which may be difficult using the decay and rebound method.

scholarly journals Effects of Neighboring Units on the Estimation of Particle Penetration Factor in a Modeled Indoor Environment

Urban Science ◽  
2020 ◽  
Vol 5 (1) ◽  
pp. 2
Author(s):  
Yonghang Lai ◽  
Ian A. Ridley ◽  
Peter Brimblecombe
Keyword(s):  
Air Quality ◽  
Indoor Air Quality ◽  
Deposition Rate ◽  
Indoor Air ◽  
Particle Deposition ◽  
Weather Conditions ◽  
Penetration Factor ◽  
Particle Penetration ◽  
Indoor Pm2.5 ◽  
Pm2.5 Concentration

Ingress of air from neighboring apartments is an important source of fine particulate matter (PM2.5) in residential multi-story buildings. It affects the measurement and estimation of particle deposition rate and penetration factor. A blower-door method to measure the particle deposition rate and penetration factor has previously been found to be more precise than the traditional decay-rebound method as it reduces variability of PM2.5 ingress from outside. CONTAM is a multi-zone indoor air quality and ventilation analysis computer program to aid the prediction of indoor air quality. It was used in this study to model the indoor PM2.5 concentrations in an apartment under varying PM2.5 emission from neighboring apartments and window opening and closing regimes. The variation of indoor PM2.5 concentration was also modeled for different days to account for typical outdoor variations. The calibrated CONTAM model aimed to simulate environments found during measurement of particle penetration factor, thus identifying the source of error in the estimates. Results show that during simulated measurement of particle penetration factors using the blower-door method for three-hour periods under a constant 4 Pa pressure difference, the indoor PM2.5 concentration increases significantly due to PM2.5 generated from adjacent apartments, having the potential to cause an error of more than 20% in the estimated value of particle penetration factor. The error tends to be lower if the measuring time is extended. Simulated measurement of the decay-rebound method showed that more PM2.5 can penetrate inside if the PM2.5 was generated from apartments below under naturally variable weather conditions. A multiple blower-door fan can be used to reduce the effects of neighboring emission and increase the precision of the penetration estimates.

Indoor particle dynamics in schools: Determination of air exchange rate, size-resolved particle deposition rate and penetration factor in real-life conditions

2015 ◽  
Vol 26 (10) ◽  
pp. 1335-1350 ◽  
Author(s):  
Dinh Trinh Tran ◽  
Laurent Y Alleman ◽  
Patrice Coddeville ◽  
Jean-Claude Galloo
Keyword(s):  
Deposition Rate ◽  
Particle Deposition ◽  
Particle Density ◽  
Real Life ◽  
Particle Dynamics ◽  
Ventilation Rate ◽  
Rate Coefficients ◽  
Particle Size Fractions ◽  
Penetration Factor

Indoor and outdoor airborne particles, CO, CO2 levels and comfort parameters were monitored at two naturally ventilated elementary schools (S1 and S2). This paper studies the variation of ventilation rate during lectures, recreations, lunchtime and after class. Additionally, mass balance equations were used to estimate the particle deposition rates and penetration factors for different particle size fractions. The originality of the present work resides in taking advantage of occupants’ activities as sources of indoor particles and tracer gas CO2 used to simultaneously estimate the above-mentioned parameters in different scenarios. This simple approach makes the determination of indoor particle dynamics more effective, and allows reducing the cost of indoor air quality studies. During the class, the ventilation rates at S1 and S2 fluctuated largely from day to day, with respective average values of 10.08 m3/h/p and 7.92 m3/h/p, significantly lower than the ASHRAE acceptable value (18 m3/h/p) in classrooms. The particle deposition loss rate coefficients for 0.3–10 µm particles dramatically increased from 0.16–0.18 h−1 for the 0.3–0.5 µm fraction to 1.81–2.31 h−1 for the 7.5–10 µm fraction, while their corresponding penetration factors declined from 0.94 to 0.30, respectively. The difference in deposition rate between schools was probably associated to discrepancies in particle density.

Measurement of particle deposition rates in a commercial aircraft cabin

2014 ◽  
Vol 20 (7) ◽  
pp. 770-779 ◽  
Author(s):  
Robert W. Powell ◽  
Byron W. Jones ◽  
Mohammad H. Hosni
Keyword(s):  
Particle Deposition ◽  
Commercial Aircraft ◽  
Deposition Rates ◽  
Aircraft Cabin

scholarly journals Airflow and Particle Deposition in Acinar Models with Interalveolar Septal Walls and Different Alveolar Numbers

2018 ◽  
Vol 2018 ◽  
pp. 1-18 ◽  
Author(s):  
Jinxiang Xi ◽  
Mohamed Talaat ◽  
Hesham Tanbour ◽  
Khaled Talaat
Keyword(s):  
Deposition Rate ◽  
Particle Deposition ◽  
Orientation Angle ◽  
Structural Complexity ◽  
Particle Dispersion ◽  
Breath Holding ◽  
Complex Models ◽  
Tracking Model ◽  
Lagrangian Tracking ◽  
Collateral Ventilation

Unique features exist in acinar units such as multiple alveoli, interalveolar septal walls, and pores of Kohn. However, the effects of such features on airflow and particle deposition remain not well quantified due to their structural complexity. This study aims to numerically investigate particle dynamics in acinar models with interalveolar septal walls and pores of Kohn. A simplified 4-alveoli model with well-defined geometries and a physiologically realistic 45-alveoli model was developed. A well-validated Lagrangian tracking model was used to simulate particle trajectories in the acinar models with rhythmically expanding and contracting wall motions. Both spatial and temporal dosimetries in the acinar models were analyzed. Results show that collateral ventilation exists among alveoli due to pressure imbalance. The size of interalveolar septal aperture significantly alters the spatial deposition pattern, while it has an insignificant effect on the total deposition rate. Surprisingly, the deposition rate in the 45-alveoli model is lower than that in the 4-alveoli model, indicating a stronger particle dispersion in more complex models. The gravity orientation angle has a decreasing effect on acinar deposition rates with an increasing number of alveoli retained in the model; such an effect is nearly negligible in the 45-alveoli model. Breath-holding increased particle deposition in the acinar region, which was most significant in the alveoli proximal to the duct. Increasing inhalation depth only slightly increases the fraction of deposited particles over particles entering the alveolar model but has a large influence on dispensing particles to the peripheral alveoli. Results of this study indicate that an empirical correlation for acinar deposition can be developed based on alveolar models with reduced complexity; however, what level of geometry complexity would be sufficient is yet to be determined.

Impact of Deposition Rate on the Structural and Magnetic Properties of Sputtered Ni/Cu Multilayer Thin Films

2017 ◽  
Vol 73 (1) ◽  
pp. 85-90 ◽  
Author(s):  
Ali Karpuz ◽  
Salih Colmekci ◽  
Hakan Kockar ◽  
Hilal Kuru ◽  
Mehmet Uckun
Keyword(s):  
Thin Films ◽  
Magnetic Properties ◽  
Deposition Rate ◽  
High Rate ◽  
Cubic Phase ◽  
High Deposition Rate ◽  
Multilayer Thin Films ◽  
Face Centered Cubic ◽  
Deposition Rates ◽  
Cu Films

AbstractThe structural and corresponding magnetic properties of Ni/Cu films sputtered at low and high deposition rates were investigated as there is a limited number of related studies in this field. 5[Ni(10 nm)/Cu(30 nm)] multilayer thin films were deposited using two DC sputtering sources at low (0.02 nm/s) and high (0.10 nm/s) deposition rates of Ni layers. A face centered cubic phase was detected for both films. The surface of the film sputtered at the low deposition rate has a lot of micro-grains distributed uniformly and with sizes from 0.1 to 0.4 μm. Also, it has a vertical acicular morphology. At high deposition rate, the number of micro-grains considerably decreased, and some of their sizes increased up to 1 μm. The surface of the Ni/Cu multilayer deposited at the low rate has a relatively more grainy and rugged structure, whereas the surface of the film deposited at the high rate has a relatively larger lateral size of surface grains with a relatively fine morphology. Saturation magnetisation, Ms, values were 90 and 138 emu/cm3 for deposition rates of 0.02 and 0.10 nm/s, respectively. Remanence, Mr, values were also found to be 48 and 71 emu/cm3 for the low and high deposition rates, respectively. The coercivity, Hc, values were 46 and 65 Oe for the low and high Ni deposition rates, respectively. The changes in the film surfaces provoked the changes in the Hc values. The Ms, Mr, and Hc values of the 5[Ni(10 nm)/Cu(30 nm)] films can be adjusted considering the surface morphologies and film contents caused by the different Ni deposition rates.

Atmospheric deposition and canopy interactions of nitrogen in forests

1993 ◽  
Vol 23 (8) ◽  
pp. 1603-1616 ◽  
Author(s):  
Gary M. Lovett ◽  
Steven E. Lindberg
Keyword(s):  
Linear Function ◽  
Dry Deposition ◽  
Wet Deposition ◽  
Particle Deposition ◽  
Cloud Water ◽  
Organic N ◽  
Total System ◽  
Inorganic N ◽  
Deposition Rates ◽  
Total Deposition

Wet deposition of nitrogen compounds was measured and dry and cloud water deposition were estimated at 11 forested sites in North America and one site in Europe. Dry deposition was a significant pathway of N input to all the forests, averaging 46% of the total deposition. At most of these sites, NH4+ was the dominant form of fixed N in the air, but HNO3 vapor dominated the dry deposition of N. Coarse-particle deposition was often important, but fine-particle deposition usually contributed only a small amount of the dry-deposited N. The deposition rates of inorganic N, which ranged between 4.8 and 27 kg N•ha−1•year−1, were generally much higher than has been reported by other studies measuring only wet or bulk deposition. The highest deposition rates were at the high-elevation sites in the southeastern and northeastern United States and much of the deposition at these sites was attributed to cloud water. Throughfall and stemflow (TF + SF) flux was also measured at all sites, and the net canopy exchange (NCE = (TF + SF)–total deposition) was found to be negative (indicating consumption of N in the canopy) for NH4+ and NO3−, and positive (indicating canopy release) for organic N. Past reports of canopy release of NO3− can probably be attributed to washoff of dry-deposited NO3− species. Consumption of inorganic N in the canopy ranged from 1 to 12 kg N•ha−1•year−1, and was highest in the spruce and spruce–fir stands. When organic N was included in the canopy N balance, the net canopy uptake of N was generally < 15% of the total system N requirement. Total N deposition was a linear function of wet deposition for low-elevation sites, and dry deposition was a linear function of the net throughfall flux for NO3−.

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