Browsing by Author "Tsai, Chuen-Jinn"

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A detailed numerical study on the evolution of droplet size distribution of dibutyl phthalate in a laminar flow diffusion chamber
(2020-03-01)
Jia, Feng
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Li, Zi-Yi
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Pui, David Y. H.
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Tsai, Chuen-Jinn
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環境工程研究所
A numerical model was used to study the homogeneous nucleation process of dibutyl phthalate (DBP) vapor in a laminar flow diffusion chamber (LFDC); the spatial and temporal evolution of DBP droplet size distribution was governed by the population balance equation (PBE). In the PBE, the nucleation rate was calculated by the self-consistent correction nucleation theory (SCCNT), droplet coagulation, vapor and droplet deposition losses were considered. The simulation results showed that the nucleation rate predicted by the SCCNT improved the underestimation of that predicted by the classical nucleation theory. Due to vapor deposition before nucleation and droplet deposition after nucleation on the wall, the DBP mass loss was severe, accounting for about 86.3% of the total inlet vapor mass, and the droplet size distribution shifted towards larger diameters. The simulation results agreed well with the experimental data in terms of the droplet size distribution and average number concentration at the outlet of the LFDC because of the detailed droplet dynamic, transport and deposition mechanisms treated in this model. Based on this model, the number of molecules in the critical cluster was calculated using the first nucleation theorem and found to be larger about 50% than that calculated using the Gibbs-Thompson equation.
A mass correction method for the aerosol particle mass analyzer to measure the particle mass of sub-50 nm nanoparticles
(1970-01-01)
Liao, Bo-Xi
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Gong, Wen-Cheng
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Li, Ziyi
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Tsai, Chuen-Jinn
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環境工程研究所
The particle mass measurement instrument of the aerosol particle mass analyzer (APM) tends to underestimate the particle mass of sub-50 nm nanoparticles, limiting the APM mass measurement to larger particles. In the present work, a mass correction method was developed based on a calibration reference to correct the APM mass underestimation according to a measured mass-based dimensionless parameter The correction was tested using laboratory generated silver nanoparticles and ambient nanoparticles. It was found that the measured effective density variations of silver nanoparticles due to different extent of APM mass underestimation at different operating conditions were reduced by the correction method with a significant improvement of R-squared from 0.40 to 0.87. In addition, about 20% increase in the effective density from 0.91 to 1.09 g/cm(3) was observed for 30 nm ambient wet nanoparticles using the correction method. The difference between the raw and corrected effective densities is due to the mass underestimation by the APM itself, which should be corrected in the data analysis program of the APM. Copyright (c) 2019 American Association for Aerosol Research
A Modified Deutsch-Anderson Equation for Predicting the Nanoparticle Collection Efficiency of Electrostatic Precipitators
(2012-10-01)
Lin, Guan-Yu
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Chen, Tzu-Ming
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Tsai, Chuen-Jinn
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環境工程研究所
;
Institute of Environmental Engineering
It is of great importance to mitigate nanoparticle exposure in the environment by using effective control devices. For controlling nanoparticles with the particle diameter (d(p)) < 100 nm in the air environment, electrostatic precipitators (ESPs) are widely used in many industries because of their low pressure drop and high removal efficiency. However, existing models cannot predict the nanoparticle collection efficiency very well. This is due to the partial charging effect, when some nanoparticles are not charged but penetrate through the ESPs, resulting in a decrease in the collection efficiency. In this study, a modified Deutsch-Anderson model was developed to predict the nanoparticle collection efficiency (eta, %), as well as that for particles with d(p) > 100 nm. The present model is eta(%) = [1 - exp(-A(N-De)(B)) + C(N-De) - (1 - alpha)] x 100%, where A, B, and C are regression coefficients, NDe is the modified Deutsch number, and a is the partial charging factor. Good agreement was obtained between the present predictions and experimental data published in the literature. It is expected that the modified equation can facilitate the design and scale-up of the ESPs for controlling nanoparticle emissions, as well as particle in all size ranges.
A New Cross-Flow Tube Bundle Heat Exchanger with Staggered Hot and Cold Tubes for Thermophoretic Deposition of Submicron Aerosol Particles
(2009)
Chien, Chih-Liang
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Huang, Shih-Hsuan
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Tsai, Chuen-Jinn
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環境工程研究所
;
Institute of Environmental Engineering
A new tube cross-flow bundle heat exchanger has been designed and tested for thermophoretic deposition of submicron aerosol particles. The present design has five columns of hot and cold square tubes, respectively, arranged in a staggered manner to maintain a nearly constant temperature gradient in the direction of the aerosol flow. Each column has four tubes of 4 mm x 4 mm in cross section and the gap between the tube surfaces is 0.5 mm. The precipitator was tested experimentally using monodisperse NaCl test particles ranging from 38 to 397 nm in diameter at the aerosol flow rate of 0.6 and 1.2 L/min, respectively, at different temperature gradients. Results showed that the thermophoretic deposition efficiency increased with decreasing aerosol flow rate and increasing temperature gradient with the maximum thermophoretic deposition efficiency occurred at the aerosol flow rate of 0.6 L/min. The effect of inlet temperature of the aerosol flow on the efficiency was also tested and showed increasing inlet temperature increased the deposition efficiency. Numerical simulation was further conducted to validate the experimental data and good agreement was obtained. An empirical equation was also validated to facilitate the design and scale-up of the precipitator.
A Novel Multifilter PM(10)-PM(2.5) Sampler (MFPPS)
(2011-01-01)
Liu, Chun-Nan
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Chen, Sheng-Chieh
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Tsai, Chuen-Jinn
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環境工程研究所
;
Institute of Environmental Engineering
A novel multifilter PM(10)-PM(2.5) sampler (MFPPS) that enables the collection of four PM(10) and four PM(2.5) samples simultaneously has been developed and tested. The MFPPS uses a PM(10) impactor as the inlet and operates at 33.4 L/min. After the inlet, the aerosol flow is divided half by a Y-type fitting. Half of the flow is directed into four PM(10) filter cassettes, while the other half is directed into four PM(2.5) filter cassettes after the aerosols are further classified by a PM(2.5) impactor. An active flow control system consisting of two mass flow controllers (MFCs), one for PM(10) and the other for PM(2.5), is used to fix the total flow rate of 16.7 L/min for four PM(10) or four PM(2.5) channels based on the ambient pressure and temperature. To ensure flow rate uniformity through each of the four PM(10) or four PM(2.5) filter cassettes, an orifice is assembled behind each of the filter cassettes to increase the pressure drop, such that the flow rates of eight sampling lines are nearly equal using just two MFCs. The MFPPS was calibrated in the laboratory for particle collection efficiency curves first. Then, the ambient PM concentrations were compared with those of other two collocated FRM samplers, the dichotomous PM(10) and the EPA WINS PM(2.5) sampler in the field study. Calibration results showed the cutoff aerodynamic diameters of the PM(10) and PM(2.5) impactors were 9.8 +/- 0.1 and 2.5 +/- 0.05 mu m, respectively. Field comparison results indicated PM(10) and PM(2.5) concentrations agreed well with the other two PM samplers.
A Novel Multifilter PM10-PM2.5 Sampler (MFPPS)
(2011-01-01)
Liu, Chun-Nan
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Chen, Sheng-Chieh
;
Tsai, Chuen-Jinn
;
環境工程研究所
;
Institute of Environmental Engineering
A novel multifilter PM10-PM2.5 sampler (MFPPS) that enables the collection of four PM10 and four PM2.5 samples simultaneously has been developed and tested. The MFPPS uses a PM10 impactor as the inlet and operates at 33.4 L/min. After the inlet, the aerosol flow is divided half by a Y-type fitting. Half of the flow is directed into four PM10 filter cassettes, while the other half is directed into four PM2.5 filter cassettes after the aerosols are further classified by a PM2.5 impactor. An active flow control system consisting of two mass flow controllers (MFCs), one for PM10 and the other for PM2.5, is used to fix the total flow rate of 16.7 L/min for four PM10 or four PM2.5 channels based on the ambient pressure and temperature. To ensure flow rate uniformity through each of the four PM10 or four PM2.5 filter cassettes, an orifice is assembled behind each of the filter cassettes to increase the pressure drop, such that the flow rates of eight sampling lines are nearly equal using just two MFCs. The MFPPS was calibrated in the laboratory for particle collection efficiency curves first. Then, the ambient PM concentrations were compared with those of other two collocated FRM samplers, the dichotomous PM10 and the EPA WINS PM2.5 sampler in the field study. Calibration results showed the cutoff aerodynamic diameters of the PM10 and PM2.5 impactors were 9.8 +/- 0.1 and 2.5 +/- 0.05 mu m, respectively. Field comparison results indicated PM10 and PM2.5 concentrations agreed well with the other two PM samplers.
A numerical modelling study of SO2 adsorption on activated carbons with new rate equations
(2018-12-01)
Li, Ziyi
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Liu, Yingshu
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Wang, Haihong
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Tsai, Chuen-Jinn
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Yang, Xiong
Modelling dynamic adsorption of sulfur dioxide (SO2) on activated carbons (ACs) is significant in guiding practical desulphurization processes and making highly efficient use of adsorbents in terms of the adsorption rate which largely depends on particle size. In this work, models derived from the Vermeulen and an improved linear driving force (LDF) rate equation were studied for the first time on SO2 adsorption over AC particles with different sizes. For larger particles (>= 3 mm), breakthrough curves predicted by the Vermeulen equation showed good agreement with experimental data, demonstrating that intraparticle diffusion resistance varied with particle size, feed concentration, adsorption time and location. For smaller particles (1 mm), a correction on the volume-averaged adsorption capacity as a function of adsorption time and saturation in the rate equation was developed to avoid the underestimation of adsorption rate due to the inappropriate parabolic concentration profile inherent in the conventional LDF model. By providing a concentration gradient and adsorption rate closer to actual values, the improved LDF equation was confirmed to provide excellent prediction results on 1-mm particles. Different modelling characteristics of the two models indicates varying effects of intraparticle diffusion on adsorption rate with particle size regarding the specificity of SO2 physisorption on ACs.
A parallel plate wet denuder for acidic gas measurement
(2008-08-01)
Tsai, Chuen-Jinn
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Lin, Guan-Yu
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Chen, Sheng-Chieh
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環境工程研究所
;
Institute of Environmental Engineering
A parallel plate wet denuder (PPWD) was designed and tested for acidic gas absorption in this studY. The PPWD is composed of two fi-osted glass plates coated with nano-TiO? particles. The gap of the plates is 4 inin, the active sinjace is 7.5 cut in width and 15 cin in height. The DI water is,flowing downward along the sulf ces to form a icn forni tvaterfilm to absorb the gas.flowing uptvard along the gap. The gas absorption efficiency and nienzory eft ct were tested using test gases of HF (3.573.80 ppb), HCl (0.48-15.63 pph), and HN03 (8.43-20.92 ppb) generatedfi-oni per"leation tubes at the flow rate of 5-10 Llinin, scrubbing DI water flow rate oj'].O n?Llnlilll plate, and PH = 6.8 -_ 0.3. The experiment was also conducted for HF and HCl with scrubbing water PH value ol'3.08 and 4.10 to examine the ffcct of PH oil the absorption efficiency. The experimental data at different.flow rates match with the theoretical values ver ' N7 well assuming peifect absorption condition (it the water filin when the scrubbing water PH = 6.8 +/- 0.3. The absorption efficiency of the three gases at the sampling flow rate of 5 Llinin was nearly 100% when the scrubbing water PH value was 6.8 +/- 0.3, but was ' found to decrease slightl ' v when the PH value of scrubbing tvater was reduced from 6.8 to 3.08, which indicates slight inodification of' peifect absorption condition at the water filin. The meniory cffect test showed that the rise time was 15 to 25 min and the fiall tinie was 10 to 25 iniiijbi- the three gases. Good un ft)rniit_v Qfthe tvater filin was observed during the 9-day ainbient air sampling for HF, 110, and HNO,, which indicates the applicabilitly (the present PPWD for ambient air sampling. (c) 2008 American Institute of Chemical Engineers.
A real-time monitoring system for soluble gas pollutants and it's application for determining the control efficiency of packed towers
(2015-11-05)
Chien, Chih-Liang
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Iswara, Aditya Prana
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Liou, Yi-Ling
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Wang, Bing-Tsai
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Chang, Jui-Chiao
This study used a parallel-plate wet denuder coupled with an ion chromatograph (PPWD-IC) to monitor soluble gas pollutants in the exhaust stack and investigate the removal efficiency of packed towers. Gas pollutant concentrations measured by the PPWD-IC system were first validated with those obtained by a manual porous metal denuder sampler (PDS) as the reference sampler. The measured concentrations of the PPWD-IC system are in good agreement with those of the PDS with the coefficient of determination (R-2) greater than 0.93. The PPWD-IC system was then used to determine the removal efficiency of packed towers in high-tech factories. Results show that the PPWD-IC system is able to monitor multiple high-concentration gas pollutants semi-continuously, such as HF, HCl, HNO2, HNO3, CH3COOH, and NH3, in the exhaust stack with a temporal resolution of 20 min. The PPWD-IC system was employed to test the gas removal efficiency of a new honeycomb wet scrubber in an optoelectronic factory. The removal efficiency of the wet scrubber equipped with the honeycomb module at the liquid-to-gas ratio of 18.5 L/m(3) is shown to be close to 100% for HF (112.4-448.4 ppbv) and CH3COOH (696.3-6537.0 ppbv) and 99% for HCI (3394,9-10794.5 ppbv), respectively. (C) 2015 Elsevier B.V. All rights reserved.
A review on recent progress in observations, sources, classification and regulations of PM2.5 in Asian environments
(2016-11)
Gautam, Sneha
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Yadav, Ankit
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Tsai, Chuen-Jinn
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Kumar, Prashant
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環境工程研究所
Natural and human activities generate a significant amount of PM2.5 (particles aecurrency sign2.5 mu m in aerodynamic diameter) into the surrounding atmospheric environments. Because of their small size, they can remain suspended for a relatively longer time in the air than coarse particles and thus can travel long distances in the atmosphere. PM2.5 is one of the key indicators of pollution and known to cause numerous types of respiratory and lung-related diseases. Due to poor implementation of regulations and a time lag in introducing the vehicle technology, levels of PM2.5 in most Asian cities are much worse than those in European environments. Dedicated reviews on understanding the characteristics of PM2.5 in Asian urban environments are currently missing but much needed. In order to fill the existing gaps in the literature, the aim of this review article is to describe dominating sources and their classification, followed by current status and health impact of PM2.5, in Asian countries. Further objectives include a critical synthesis of the topics such as secondary and tertiary aerosol formation, chemical composition, monitoring and modelling methods, source apportionment, emissions and exposure impacts. The review concludes with the synthesis of regulatory guidelines and future perspectives for PM2.5 in Asian countries. A critical synthesis of literature suggests a lack of exposure and monitoring studies to inform personal exposure in the household and rural areas of Asian environments.
A size-segregation method for monitoring the diurnal characteristics of atmospheric black carbon size distribution at urban traffic sites
(2014-06-01)
Cheng, Yu-Hsiang
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Liao, Chung-Wen
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Liu, Zhen-Shu
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Tsai, Chuen-Jinn
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Hsi, Hsing-Cheng
Understanding the characteristics of the size distribution of ambient black carbon (BC) in distinct environments is critical because the influence of BC aerosols on climate, visibility, and human health depends strongly on the distribution of BC aerosols over the particle size spectrum. In this study, a novel method for determining the mass size distribution of BC in atmospheric aerosols was developed. This size-segregation method relies on measuring BC in parallel using two aethalometers, one of which is used to measure the total BC (BCT) mass concentration as a reference level and the other is used to measure the BC (BC;) mass concentration for BC sizes below specific particle sizes that are selected using a size cut-off inlet. In this study, this method was applied to measure BC in atmospheric samples at an urban traffic site. The aethalometers were operated continually from December 15, 2012 to January 31, 2013, and from February 15, 2013 to March 31, 2013. The measurement results presented in this paper are for the diurnal variation patterns, average concentrations, mass fractions, and size distributions of BC aerosols. The results indicate that BC T mass concentration is approximately 2.8 mu g m(-3) in the Taipei urban area. The levels of BC at this sampling site were affected markedly by traffic emission levels and local wind speed. At the sampling site, the average BC2.5/BCT; BC1.0/BCT, BC0.5/BCT, BC0.25/BCT, and BC0.1/BCT were 0.96 +/- 0.04, +/- 0.92 +/- 0.07, 0.89 +/- 0.04, 0.73 +/- 0.10, and 0.18 +/- 0.08, respectively. The results indicate that approximately 90% of the BC aerosols were smaller than 0.5 mu m, that most of the BC aerosols (55%) were in the size range of 0.1-0.25 mu m, and that approximately 18% of the BC aerosols were ultrafine. Moreover, the daily average mass size distribution of BC exhibited a single accumulation mode at 0.16 gm at this sampling site. The mode of the BC mass size distribution at rush hour (9 AM) was only 0.14 mu m, which is smaller than the daily average. Moreover, the mode of the BC mass size distribution at an early morning hour (3 AM) was 0.18 mu m, and a minor coarse mode was also observed during this period. The results further revealed that the geometric diameter (D-pg) of the BC aerosols varied between 0.14 and 0.22 mu m and the geometric standard deviation (sigma(g)) of these BC aerosols ranged between 1.4 and 2.3 during the sampling period. Because BC exhibits extremely low chemical reactivity; the size distribution of BC in the atmosphere does not change substantially except through coagulation. (c) 2014 Elsevier Ltd. All rights reserved.
Adsorption phenomena and related mechanisms of airborne nanoparticles on porous materials
(2018-08-19)
Li, Ziyi
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Liu, Yingshu
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Tsai, Chuen-Jinn
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Xing, Yi
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Lu, Pei
An axial flow cyclone to remove nanoparticles at low pressure conditions
(2007-01-01)
Chen, Sheng-Chieh
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Tsai, Chuen-Jinn
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環境工程研究所
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Institute of Environmental Engineering
In this study, the axial flow cyclone used in Tsai et al. (2004) was further tested for the collection efficiency of both solid (NaCl) and liquid (OA, oleic acid) nanoparticles. The results showed that the smallest cutoff aerodynamic diameters achieved for OA and NaCl nanoparticles were 21.7 nm (cyclone inlet pressure: 4.3 Torr, flow rate: 0.351 slpm) and 21.2 nm (5.4 Torr, 0.454 slpm), respectively. The collection efficiencies for NaCl and OA particles were close to each other for the aerodynamic diameter ranging from 25 to 180 nm indicating there was almost no solid particle bounce in the cyclone. The 3-D numerical simulation was conducted to calculate the flow field in the cyclone and the flow was found to be nearly paraboloid. Numerical simulation of the particle collection efficiency based on the paraboloid flow assumption showed that the collection efficiency was in good agreement with the experimental data with less than 15% of error. A semi-empirical equation for predicting the cutoff aerodynamic diameter at different inlet pressures and flow rates was also obtained. The semi-empirical equation is able to predict the cutoff aerodynamic diameter accurately within 9% of error. From the empirical cutoff aerodynamic diameter, a semi-empirical square root of the cutoff Stokes number, root St*(50), was calculated and found to be a constant value of 0.241. This value is useful to the design of the cyclone operating in vacuum to remove nanoparticles.
An Efficient Single-Stage Wet Electrostatic Precipitator for Fine and Nanosized Particle Control
(2010)
Lin, Guan-Yu
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Tsai, Chuen-Jinn
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Chen, Sheng-Chieh
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Chen, Tzu-Ming
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Li, Shou-Nan
In this study, an efficient parallel-plate single-stage wet electrostatic precipitator (wet ESP) with a width of 75 mm, effective precipitation length of 48 mm and gap of 9.0 mm was designed and tested to control fine and nanosized particles without the need of rapping. The collection plates are made of sand-blasted copper plates coated with TiO(2) nanopowder instead of hydrophilic membranes. Three gold wires (diameter: 100 mu m) were used as the discharge electrodes and a pulse jet valve was used to regularly purge the wires. The design of the present wet ESP is aimed at solving the problems of traditional dry ESPs: reduction of the collection efficiency due to particle deposition on the discharge electrodes and collection electrodes, back corona, and particle re-entrainment. The collection efficiency at initially clean and heavy particle loading conditions was tested and compared to a similar dry ESP. Experimental results showed that when the wet ESP was initially clean, the particle collection efficiency ranged from 96.9-99.7% for particles ranging from 16.8 to 615 nm in electrical mobility diameter at an aerosol flow rate of 5 L/min (residence time of 0.39 s) and an applied voltage of 4.3 kV. After heavy loading with TiO(2) nanopowder about 1.2 +/- 0.06 g/plate, the collection efficiency of the present wet ESP for corn oil particles was shown to reduce only slightly to 94.7-99.0% for particles from 16.8 to 615 nm in diameter.
An efficient wet electrostatic precipitator for removing nanoparticles, submicron and micron-sized particles
(2014-11-05)
Chen, Tzu-Ming
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Tsai, Chuen-Jinn
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Yan, Shaw-Yi
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Li, Shou-Nan
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環境工程研究所
An efficient wire-to-plate single-stage wet electrostatic precipitator (WESP) was designed and tested to control nanoparticles, submicron and micron-sized particles emitted from semiconductor manufacturing processes. Tungsten-wires of 0.36 mm in diameter were used as discharge electrodes and a fixed voltage of -15 kV was supplied to generate the electric field and corona ions. Fine water mist at room temperature was used to quench the high temperature exhaust gas to enhance particle condensation growth and improve the collection efficiency of nanoparticles. Experimental results showed that without fine water mist, nanoparticle collection efficiency was 67.9-92.9%, which was greatly enhanced to 99.2-99.7% when the WESP was operated with fine water mist. A predictive method was developed to calculate the particle collection efficiency equation eta(%) in the form as eta(%) = [1 - exp(-alpha(N-De)(beta) + gamma)] x 100%, in which alpha, beta and gamma are regression coefficients and N-De is the Deutsch number. Good agreement was obtained between present predictions and experimental data. For longer term operation, the periodic wall-cleaning water was used to clean discharge electrodes and collection electrodes regularly. In the field tests, the total collection efficiencies (40 <= d(p) <= 8100 nm) of the WESP were found to maintain greater than 98.7% and 97.3% for continuous operation for 35 and 22 day at fab A and fab B, respectively. (C) 2014 Elsevier B.V. All rights reserved.
An Online Parallel-Plate Wet Denuder System for Monitoring Acetic Acid Gas
(2010-10-01)
Ku, Yueh-Ping
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Yang, Caddie
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Lin, Guan-Yu
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Tsai, Chuen-Jinn
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環境工程研究所
In air environments, acetic acid gas may lead to irritations, generate pungent odor, and cause objects to corrode. This paper examines an online parallel-plate wet denuder system to monitor gaseous acid at ppbv concentration levels. Denuder surfaces which comprised frosted glass plates coated with a thin layer of TiO(2) nanoparticles were covered by a thin film made of ultrapure water or 0.5 mM H(2)O(2) to absorb the test acetic gases that were generated from a small thermostatic evaporation tube. Denuder effluent was then injected automatically into an ion chromatography for real-time detection. The method was validated by comparing measured concentrations with those obtained simultaneously by using a well established impinger technique. Test results showed that the current technique is an efficient collector for gaseous acetic acid, achieving the collection efficiency between 93.8% to 96.4% by using ultrapure water film. It can monitor 0.9-698.0 ppbv gaseous acetic acid accurately in real-time with response time of 10 minutes, a detection limit of 1.2 ppbv and a time resolution of either 10 minutes or 20 minutes, depending on the concentration of the eluent used in the ion chromatography. The technique was applied successfully to measure the exposure concentration of acetic acid gas leaking from a fume hood in a laboratory.
An overview of regional experiments on biomass burning aerosols and related pollutants in Southeast Asia: From BASE-ASIA and the Dongsha Experiment to 7-SEAS
(2013-10-01)
Lin, Neng-Huei
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Tsay, Si-Chee
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Maring, Hal B.
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Yen, Ming-Cheng
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Sheu, Guey-Rong
By modulating the Earth-atmosphere energy, hydrological and biogeochemical cycles, and affecting regional-to-global weather and climate, biomass burning is recognized as one of the major factors affecting the global carbon cycle. However, few comprehensive and wide-ranging experiments have been conducted to characterize biomass-burning pollutants in Southeast Asia (SEA) or assess their regional impact on meteorology, the hydrological cycle, the radiative budget, or climate change. Recently, BASE-ASIA (Biomass-burning Aerosols in South-East Asia: Smoke Impact Assessment) and the 7-SEAS (7-South-East Asian Studies)/Dongsha Experiment were conducted during the spring seasons of 2006 and 2010 in northern SEA, respectively, to characterize the chemical, physical, and radiative properties of biomass-burning emissions near the source regions, and assess their effects. This paper provides an overview of results from these two campaigns and related studies collected in this special issue, entitled "Observation, modeling and impact studies of biomass burning and pollution in the SE Asian Environment". This volume includes 28 papers, which provide a synopsis of the experiments, regional weather/climate, chemical characterization of biomass-burning aerosols and related pollutants in source and sink regions, the spatial distribution of air toxics (atmospheric mercury and dioxins) in source and remote areas, a characterization of aerosol physical, optical, and radiative properties, as well as modeling and impact studies. These studies, taken together, provide the first relatively complete dataset of aerosol chemistry and physical observations conducted in the source/sink region in the northern SEA, with particular emphasis on the marine boundary layer and lower free troposphere (LFT). The data, analysis and modeling included in these papers advance our present knowledge of source characterization of biomass-burning pollutants near the source regions as well as the physical and chemical processes along transport pathways. In addition, we raise key questions to be addressed by a coming deployment during springtime 2013 in northern SEA, named 7-SEAS/BASELInE (Biomass-burning Aerosols & Stratocumulus Environment: Lifecycles and Interactions Experiment). This campaign will include a synergistic approach for further exploring many key atmospheric processes (e.g., complex aerosol-cloud interactions) and impacts of biomass burning on the surface-atmosphere energy budgets during the lifecycles of biomass-burning emissions. (c) 2013 The Authors. Published by Elsevier Ltd. All rights reserved.
Biomass burning tracers in rural and urban ultrafine particles in Xi'an, China
(2017-07-01)
Zhu, Chong-Shu
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Cao, Jun-Ji
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Tsai, Chuen-Jinn
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Zhang, Zhi-Sheng
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Tao, Jun
To investigate the impact of biomass burning emissions on ultrafine particles (PM0.133: particulate matter with an aerodynamic diameter less than 0.133 mu m), biomass burning tracers (including levoglucosan, mannonsan and K+) were measured at a rural and an urban sites in Xi'an during winter heating period. The average levoglucosan concentrations of rural and urban PM0.133 were 0.93 +/- 0.32 mu g m(-3) and 0.29 +/- 0.14 mg m(-3), respectively. Comparable PM0.133 mannosan concentrations were observed in rural samples (0.16 +/- 0.26 mu g m(-3)) and urban samples (0.17 +/- 0.10 mu g m(-3)). Higher correlation between levoglucosan and K+ was obtained for urban samples (R = 0.86) than that for rural samples (R = 0.72). The levoglucosan to K+ ratio was found to be higher for rural samples (0.77 +/- 0.39) compared to that for urban samples (0.32 +/- 0.14). Levoglucosan to mannosan ratios averaged 7.86 and 2.83 for rural and urban samples, respectively. It can be concluded that the major source of rural biomass burning was the combustion of crop residuals and softwood. The contributions of biomass burning to OC ranged from 19% to 32%, with an average of 24% for rural samples. The results provide a better understanding on the rural and urban magnitude of levoglucosan and contributions of biomass burning in Xi'an. (C) 2017 Turkish National Committee for Air Pollution Research and Control. Production and hosting by Elsevier B.V. All rights reserved.
Characteristic of nanoparticles generated from different nano-powders by using different dispersion methods
(2012-04-01)
Tsai, Chuen-Jinn
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Lin, Guan-Yu
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Liu, Chun-Nan
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He, Chi-En
;
Chen, Chun-Wan
A standard rotating drum with a modified sampling train (RD), a vortex shaker (VS), and a SSPD (small-scale powder disperser) were used to investigate the emission characteristics of nano-powders, including nano-titanium dioxide (nano-TiO2, primary diameter: 21 nm), nano-zinc oxide (nano-ZnO, primary diameter: 30-50 nm), and nano-silicon dioxide (nano-SiO2, primary diameter: 10-30 nm). A TSI SMPS (scanning mobility particle sizer), a TSI APS (aerodynamic particle sizer), and a MSP MOUDI (micro-orifice uniform deposit impactor) were used to measure the number and mass distributions of generated particles. Significant differences in specific number and mass concentration or distributions were found among different methods and nano-powders with the most specific number and mass concentration and the smallest particles being generated by the most energetic SSPD, followed by VS and RD. Near uni-modal number or mass distributions were observed for the SSPD while bi-modal number or mass distributions existed for nano-powders except nano-SiO2 which also exhibited bimodal mass distributions. The 30-min average results showed that the mass median aerodynamic diameter (MMAD) and number median diameter (NMD) of the SSPD ranged 1.1-2.1 mu m and 166-261 nm, respectively, for all three nano-powders, which were smaller than those of the VS (MMAD: 3.3-6.0 mu m and NMD: 156-462 nm), and the RD (MMAD: 5.2-11.2 mu m and NMD: 198-479 nm). For nano-particles (electric mobility diameter < 100 nm), specific mass concentrations were nearly negligible for all three nano-powders and test methods. Specific number concentrations of nano-particles were low for the RD tester but were elevated when more energetic VS and SSPD testers were used. The quantitative size and concentration data obtained in this study is useful to elucidate the field emission and personal exposure data in the future provided that particle loss in the generation system is carefully assessed.
Characterization of Atmospheric PM(2.5)Inorganic Aerosols Using the Semi-Continuous PPWD-PILS-IC System and the ISORROPIA-II
(2020-08-01)
Le, Thi-Cuc
;
Wang, Yun-Chin
;
Pui, David Y. H.
;
Tsai, Chuen-Jinn
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環境工程研究所
A semi-continuous monitoring system, a parallel plate wet denuder and particle into liquid sampler coupled with ion chromatography (PPWD-PILS-IC), was used to measure the hourly precursor gases and water-soluble inorganic ions in ambient particles smaller than 2.5 mu m in diameter (PM2.5) for investigating the thermodynamic equilibrium of aerosols using the ISORROPIA-II thermodynamic equilibrium model. The 24-h average PPWD-PILS-IC data showed very good agreement with the daily data of the manual 5 L/min porous-metal denuder sampler with R(2)ranging from 0.88 to 0.98 for inorganic ions (NH4+, Na+, K+, NO3-, SO42-, and Cl-) and 0.89 to 0.98 for precursor gases (NH3, HNO3, HONO, and SO2) and slopes ranging from 0.94 to 1.17 for ions and 0.87 to 0.95 for gases, respectively. In addition, the predicted ISORROPIA-II results were in good agreement with the hourly observed data of the PPWD-PILS-IC system for SO42-(R-2= 0.99 and slope = 1.0) and NH3(R-2= 0.97 and slope = 1.02). The correlation of the predicted results and observed data was further improved for NH(4)(+)and NO(3)(-)with the slope increasing from 0.90 to 0.96 and 0.95 to 1.09, respectively when the HNO(2)and NO(2)(-)were included in the total nitrate concentration (TN = [NO3-] + [HNO3] + [HONO] + [NO2-]). The predicted HNO(3)data were comparable to the sum of the observed [HNO3] and [HONO] indicating that HONO played an important role in the thermodynamic equilibrium of ambient PM(2.5)aerosols but has not been considered in the ISORROPIA-II thermodynamic equilibrium model.