Theoretical and experimental analysis of turbidity fluctuations in the simultaneous measurement of particle size and aerosol concentration

Abstract. The presence of bioaerosols in swine production facilities affects the respiratory health of swine workers and pigs. Air ionization (AI) is an affordable technology for removing bioaerosols in the air. The purpose of this study was to assess the effect of AI on aerosols in a ventilated space in terms of reduction in aerosol concentration, changes in particle size distribution, and reduction of airborne Porcine Reproductive and Respiratory Syndrome virus (PRRSV). Experiments were performed in a two-chamber system in which aerosols containing PRRSV were introduced. Tests were conducted for two ventilation rates of 34 and 136 m3 h-1 and two aerosol generation rates of 14.8 and 33.0 mL h-1. The aerosol concentration and size distribution were measured with an aerosol particle size spectrometer. The average reduction in geometric mean diameter of aerosols by AI treatment ranged from 8% to 53%, and reduction in aerosol concentration ranged from 68% to 96%. Ventilation rate was found to affect the efficiency of AI in reducing aerosol concentration; the removal efficiency decreased with increased ventilation rate. The removal efficiency of AI varied with particle size. Specifically, at the low airflow rate, the removal efficiency of AI increased sharply with particle size from 70% at 0.25 µm to 95% at 0.6 µm and reached 100% for particles larger than 6 µm. At the high airflow rate, the removal efficiency varied between 50% to 80% before reaching 100% removal for particles sizes of 7 to 9 µm. The average reduction in PRRSV concentration ranged from 68% to 96%, and the residual PRRSV remaining in the air after treatment ranged from 154 to 4593 viral genome copy number (VGCN) m-3. Ozone generation by the AI system was not measured in this study, and it may be a concern due to the health risk to pigs and workers when using AI systems for removing bioaerosols. Keywords: Air ionization, Air quality, Bioaerosols, Porcine Reproductive and Respiratory Syndrome Virus, Swine.

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Simultaneous measurement of particle size, velocity, and temperature in thermal plasmas

IEEE Transactions on Plasma Science ◽

10.1109/27.61509 ◽

1990 ◽

Vol 18 (6) ◽

pp. 948-957 ◽

Cited By ~ 37

Author(s):

J.R. Fincke ◽

W.D. Swank ◽

C.L. Jeffery

Keyword(s):

Particle Size ◽

Simultaneous Measurement ◽

Thermal Plasmas

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Study on the Thermodynamics and Kinetics in the Combustion Reaction between Titanium and Boron Powders

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.351.189 ◽

2007 ◽

Vol 351 ◽

pp. 189-194 ◽

Cited By ~ 1

Author(s):

K. Wang ◽

Zheng Yi Fu ◽

Wei Min Wang ◽

Yu Cheng Wang ◽

H. Wang ◽

...

Keyword(s):

Particle Size ◽

High Temperature ◽

Low Temperature ◽

Experimental Analysis ◽

Combustion Temperature ◽

Raw Materials ◽

Temperature Range ◽

Thermodynamics And Kinetics ◽

Diffusion Controlled ◽

Calculated Activation

Combustion synthesis of titanium diboride(TiB2) from titanium(Ti) and boron(B) powders was studied by theoretical calculation and experimental analysis. In high temperature range or in low temperature range, the calculated activation energies are 140KJ/mol or 355KJ/mol respectively, which is described by a change from dissolution-precipitation controlled process to diffusion-controlled process. With the increase of particle size of the raw materials, combustion temperature and propagating rate will both reduce. The propagating rate decreases with the addition of diluents. Further increase of diluents may result in a stop of the combustion wave halfway or even a failure of ignition.

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Application of Multistep Inversion Method for Online Monitoring Aerosol Particle Size Distribution and Aerosol Concentration

Mathematical Problems in Engineering ◽

10.1155/2020/1983460 ◽

2020 ◽

Vol 2020 ◽

pp. 1-12

Author(s):

Zhenzong He ◽

Liang Xu ◽

Junkui Mao ◽

Xingsi Han ◽

Biao Zhang

Keyword(s):

Particle Size ◽

Standard Deviation ◽

Particle Size Distribution ◽

Size Distribution ◽

Sampling Time ◽

Aerosol Concentration ◽

Inversion Method ◽

Time Interval ◽

Aerosol Particle Size ◽

Sampling Time Interval

Aerosol concentration in the flow is usually time varying, and aerosol particle size distribution (PSD) is considered to be unchanged, which increases the difficulty of the measurement of aerosol PSD and concentration online. To solve these problems, a kind of multistep inversion method based on the angular light-scattering (ALS) signals is proposed. First, the aerosol PSD is estimated using shuffled frog-leaping algorithms (SFLAs) from relative ALS signals. Then, with aerosol PSD as priori information, the aerosol concentration is obtained by the Kalman filter (KF) algorithm, widely used in the real-time control system of industrial facilities for its ability of fast predictions. The result reveals that the performance of the improved SFLA is better than that of the original SFLA in solving the aerosol PSD. Moreover, in studying the aerosol concentration, more accurate results can be obtained with larger standard deviation of process noise or smaller standard deviation of measurement noise, while decreasing sampling time interval can improve the accuracy of retrieval results and reduce time delay to a certain degree. So, to improve retrieval accuracy, the noise should be controlled, and appropriate sampling time interval should be selected. All the numerical simulations confirm that the methodology provides effective and reliable results in real-time estimating.

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The Impact of Large Mobile Air Purifiers on Aerosol Concentration in Classrooms and the Reduction of Airborne Transmission of SARS-CoV-2

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph182111523 ◽

2021 ◽

Vol 18 (21) ◽

pp. 11523

Author(s):

Finn F. Duill ◽

Florian Schulz ◽

Aman Jain ◽

Leve Krieger ◽

Berend van Wachem ◽

...

Keyword(s):

Particle Size ◽

Particle Concentration ◽

Substantial Reduction ◽

Aerosol Concentration ◽

Optimal Placement ◽

Cfd Modeling ◽

Risk Of Infection ◽

Duration Of Stay ◽

Increased Risk ◽

The Impact

In the wake of the COVID-19 pandemic, an increased risk of infection by virus-containing aerosols indoors is assumed. Especially in schools, the duration of stay is long and the number of people in the rooms is large, increasing the risk of infection. This problem particularly affects schools without pre-installed ventilation systems that are equipped with filters and/or operate with fresh air. Here, the aerosol concentration is reduced by natural ventilation. In this context, we are investigating the effect of large mobile air purifiers (AP) with HEPA filters on particle concentration and their suitability for classroom use in a primary school in Germany. The three tested APs differ significantly in their air outlet characteristics. Measurements of the number of particles, the particle size distribution, and the CO2 concentration were carried out in the classroom with students (April/May 2021) and with an aerosol generator without students. In this regard, the use of APs leads to a substantial reduction of aerosol particles in the considered particle size range of 0.178–17.78 µm. At the same time, the three APs are found to have differences in their particle decay rate, noise level, and flow velocity. In addition to the measurements, the effect of various influencing parameters on the potential inhaled particle dose was investigated using a calculation model. The parameters considered include the duration of stay, particle concentration in exhaled air, respiratory flow rate, virus lifetime, ventilation interval, ventilation efficiency, AP volumetric flow, as well as room size. Based on the resulting effect diagrams, significant recommendations can be derived for reducing the risk of infection from virus-laden aerosols. Finally, the measurements were compared to computational fluid dynamics (CFD) modeling, as such tools can aid the optimal placement and configuration of APs and can be used to study the effect of the spread of aerosols from a source in the classroom.

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