Browsing by Author "Huang, Cheng-Hsiung"

Now showing 1 - 7 of 7

Application of physical vapor deposition process to modify activated carbon fibers for ozone reduction
(2008-05-01)
Lin, Yu-Chih
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Chang, Chung-Liang
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Lin, Tser-Sheng
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Bai, Hsunling
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Yan, Ming-Gu
This study utilized the activated carbon fiber (ACF) modified with metal catalyst via physical vapor deposition (PVD) process (ACF/PVD) to diminish ozone. Furthermore, the ozone removal efficiency of ACF/PVD was compared with that of original ACF and ACF modified with metal catalyst via impregnation process (ACF/impregnation). In addition to the kinds of coated metal and the inlet ozone concentrations, the effects of the coating thickness and the reaction temperature on ACF/PVD for ozone removal were also examined. The results indicate that the ozone removal efficiency of ACF/PVD is better than that of original ACF and ACF/impregnation. The ozone removal efficiency of different metal-coated ACF/PVD in the superior order is gold (Au), and manganese (Mn). The increase of Au-coated thickness (3 nm to 80 nm) on ACF/PVD will enhance the ozone removal. However, when the Mn-coated thickness on ACF/PVD is larger than 15 rim, the ozone removal efficiency displays a declining trend. Furthermore, a higher reaction temperature will result in a better ozone removal of ACF/PVD and the original ACF.
Concentrations of ultrafine particles at a highway toll collection booth and exposure implications for toll collectors
(2010-12-15)
Cheng, Yu-Hsiang
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Huang, Cheng-Hsiung
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Huang, Hsiao-Lin
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Tsai, Chuen-Jinn
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環境工程研究所
Research regarding the magnitude of ultrafine particle levels at highway toll stations is limited. This study measured ambient concentrations of ultrafine particles at a highway toll station from October 30 to November 1 and November 5 to November 6, 2008. A scanning mobility particle sizer was used to measure ultrafine particle concentrations at a ticket/cash tollbooth. Levels of hourly average ultrafine particles at the tollbooth were about 3-6 times higher than those in urban backgrounds, indicating that a considerable amount of ultrafine particles are exhausted from passing vehicles. A bi-modal size distribution pattern with a dominant mode at about <6 nm and a minor mode at about 40 nm was observed at the tollbooth. The high amounts of nanoparticles in this study can be attributed to gas-to-particle reactions in fresh fumes emitted directly from vehicles. The influences of traffic volume, wind speed, and relative humidity on ultrafine particle concentrations were also determined. High ambient concentrations of ultrafine particles existed under low wind speed, low relative humidity, and high traffic volume. Although different factors account for high ambient concentrations of ultrafine particles at the tollbooth, measurements indicate that toll collectors who work close to traffic emission sources have a high exposure risk. (C) 2010 Elsevier ay. All rights reserved.
Control efficiency of submicron particles by an efficient venturi scrubber system
(2007-04-01)
Huang, Cheng-Hsiung
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Tsai, Chuen-Jinn
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Wang, Yu-Min
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環境工程研究所
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Institute of Environmental Engineering
An efficient venturi scrubber system combining a particle growth device and a traditional venturi scrubber was designed and tested in the laboratory. Before the venturi scrubber, saturated steam at 100 degrees C was mixed with normal temperature waste stream to achieve supersaturation conditions allowing submicron particles to grow into micron sizes. Hence the control efficiency of submicron particles was greatly enhanced at a reasonably low pressure drop as compared to that found in the literature. At a flow rate of 250 L/min and a liquid to gas ratio of 2.5 L/m(3), the control efficiency of the present venturi scrubber system for NaCl particles greater than 100 nm is greater than 90%, and pressure drop is only about 44 cmH(2)O (4.3 kPa). In comparison, to remove only 50% of 0.6 mu m particles at the same liquid to gas ratio, the pressure drop needed will be greater than 200 cmH(2)O (or 19.6 kPa). Theoretical calculation has also been conducted to simulate particle growth process and the control efficiency of the venturi scrubber considering the effects of mixing ratio (ratio of steam to waste stream by mass flow rate) and particle diameter. Theoretical results using Calvert's theory (1970) were found to agree well with the experimental data for NaCl particles greater than 50 nm, and for SiO2 particles greater than 150 nm.
Enhancement of Extrinsic Charging Efficiency of a Nanoparticle Charger with Multiple Discharging Wires
(2010)
Tsai, Chuen-Jinn
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Lin, Guan-Yu
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Chen, Hui-Lin
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Huang, Cheng-Hsiung
;
Alonso, Manuel
A unipolar charger with multiple discharging wires has been developed and investigated to enhance the extrinsic charging efficiency of nanoparticles by using sheath air near the wall of the charger. The applied voltage of the charger ranged from +4.0 to +10 kV, corresponding to corona current from 0.02 to 119.63 mu A. Monodisperse NaCl particles of 10 similar to 50 nm and Ag particles of 2.5 similar to 10 nm in diameter were produced to test the performance of the charger with multiple discharging wires and to investigate the particle loss at different sheath flow rates, corona voltages and sheath air velocities. Results showed that the optimal efficiency in the charger was obtained at + 9 kV applied voltage, 10 L/min aerosol flow rate and 20 L/min sheath air flow rate. The extrinsic charging efficiency increased from 2.86% to 86.3% in the charger as the particle diameter increasing from 2.5 to 50 nm. The TDMA (tandem-differential mobility analyzer) technique was used to investigate the charge distribution, and the charge distributions in the exit were obtained at the optimal operating condition.
Exposure assessment of nano-sized and respirable particles at different workplaces
(2011-09-01)
Tsai, Chuen-Jinn
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Huang, Cheng-Yu
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Chen, Sheng-Chieh
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Ho, Chi-En
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Huang, Cheng-Hsiung
In this study, nanoparticle (NP, diameter < 100 nm) and respirable particles measurements were conducted at three different nanopowder workplaces, including the mixing area of a nano-SiO(2)-epoxy molding compound plant (primary diameter: 15 nm), bagging areas of a nano-carbon black (nano-CB) (primary diameter: 32 nm) and a nano-CaCO(3) (primary diameter: 94 nm) manufacturing plant. Chemical analysis of respirable particle mass (RPM) and NPs was performed to quantify the content of manufactured nanoparticles in the collected samples. Nanopowder products obtained from the plants were used in the laboratory dustiness testing using a rotating drum tester to obtain particle mass and number distributions. The obtained laboratory data were then used to elucidate the field data. Both field and laboratory data showed that NP number and mass concentrations of manufactured materials were close to the background level. Number concentration was elevated only for particles with the electrical mobility diameter > 100 nm during bagging or feeding processes, unless there were combustion-related incidental sources existed. Large fraction of nanomaterials was found in the RPM due to agglomeration of nanomaterials or attachment of nanomaterials to the larger particles. From this study, it is concluded that RPM concentration measurements are necessary for the exposure assessment of nanoparticles in workplaces.
Measurements of respirable dust and nanoparticle concentrations in a titanium dioxide pigment production factory
(2010)
Huang, Cheng-Hsiung
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Tai, Chih-Yuan
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Huang, Cheng-Yu
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Tsai, Chuen-Jinn
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Chen, Chun-Wan
This study compared respirable dust and nanoparticle concentrations measured by different sampling devices at a titanium dioxide pigment factory. Respirable particle mass concentrations, nanoparticle concentrations, particle size distribution and particle metallic content were measured at different sampling locations. The sampling results of the Multi-orifice Uniform Deposit Impactor (MOUDI) showed that the particle size distribution at this titanium dioxide production factory fell in the range of 1-10 mu m. Generally, the higher levels of the respirable particle mass concentrations and nanoparticle number concentrations were near the packing site of the pigment titanium dioxide production factory. Metal analysis results revealed that the titanium dioxide concentrations in respirable dust and nanoparticles were within the limits specified by National Institute for Occupational Safety and Health (NIOSH). During sampling, particle metallic content analysis is essential for identifying the source of particles and for measuring respirable dust and nanoparticle concentrations.
Prediction of dimensionless cutsize for size-fractionated measurements of particles that impact on a sintered stainless-steel filter
(2007)
Huang, Cheng-Hsiung
;
Lin, Tser-Sheng
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Chang, Sheh-Hsun
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Tsai, Chuen-Jinn
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環境工程研究所
This investigation experimentally studied the penetration curve of particles that impact on a sintered stainless-steel filter with various pore sizes, sampling flow rates and jet diameters. The penetration curves were compared to those with an aluminum foil substrate. Test data reveal that when the sintered stainless-steel filter has larger pore sizes (100 mu m or 40 mu m), the particle penetration, P(%), is lower and the curve is less steep than that obtained from the aluminum foil substrate. The penetration curve of the sintered stainless-steel filter with smaller pore size (5 mu m) is close to that of the aluminum foil substrate. The dimensionless cutsize-shift (the ratio of the dimensionless cutsize of sintered stainless-steel filter to that of aluminum foil) falls as the pore sizes and the Reynolds number increase. Experimental data were then compared with theoretical results, and theory over-predicted the dimensionless cutsize-shift. Hence, a regression equation for the dimensionless cutsize-shift is proposed by fitting the experimental data. The discrepancy between the experimental data and the regression prediction is within 4%. The regression equation can be used to predict the dimensionless cutsize for the size-fractionated measurements of particles that impact on a sintered stainless-steel filter with various sized pores and Reynolds numbers.