Browsing by Author "Hung, Yi-Hung"

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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
;
Iswara, Aditya Prana
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Liou, Yi-Ling
;
Wang, Bing-Tsai
;
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.
Collection efficiency and interstage loss of nanoparticles in micro-orifice-based cascade impactors
(2013-04-01)
Liu, Chun-Nan
;
Awasthi, Amit
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Hung, Yi-Hung
;
Tsai, Chuen-Jinn
;
環境工程研究所
In this study, two micro-orifice-based cascade impactors, including the micro-orifice uniform deposit impactor (MOUDI, MSP Model 110) and the NCTU micro-orifice cascade impactor (NMCI), were tested for the collection efficiency and interstage loss of nanoparticles. In the NMCI, new nozzle plates with smooth nozzle shape made by the LIGA (Lithography, Electroplating, and Molding) process were used to replace the 7th-10th stages in one of the MOUDI. Test results show that after adjusting proper S/W ratios (S: jet to plate distance, W: nozzle diameter) to 2.52, 3.01, 13.44, and 24.75 for the 7th, 8th, 9th and 10th stage of the NMCI, respectively, and 5.56, 11.18, 9.3, and 10.9 for the 7th, 8th, 9th and 10th stage of the MOUDI, respectively, the cutoff aerodynamic diameters (d(pa50)) are close to the nominal values given in Marple et al. (1991). Different S/W ratios are needed due to differences in the nozzle shape and nozzle diameter between two cascade impactors. Total interstage loss of nanoparticles from the inlet to the 6th-10th stage of the MOUDI exists due to the convection-diffusion mechanism, which increases with decreasing d(pa). For the MOUDI, total loss is 2.9-15.3 % (d(pa): 105.8 to 15.4 nm) for the inlet to the 6th stage and it increases to 20.1-26.1 % (d(pa): 23 to 15.4 nm) for the inlet to the 10th stage, respectively. Similar but slightly lower loss also exists in the NMCI. Field comparison tests in the ambient air show that mass size distributions measured by the MOUDI agree well with those of the NMCI. Finally, nozzle clogging tests using high concentration incense smokes indicate that the NMCI has a much less tendency for particles to clog in the nozzles than the MODUI. (C) 2012 Elsevier Ltd. All rights reserved.
Differences in 24-h average PM2.5 concentrations between the beta attenuation monitor (BAM) and the dichotomous sampler (Dichot)
(2013-08-01)
Liu, Chun-Nan
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Awasthi, Amit
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Hung, Yi-Hung
;
Gugamsetty, Balakrishnaiah
;
Tsai, Chuen-Jinn
In this study, PM2.5 concentrations were measured simultaneously by a Dichotomous sampler (Dichot, Model SA241, Andersen Inc., Georgia, USA) (PM2.5,D) and a beta attenuation monitor (BAM) (PM2.5,B) at each of three air monitoring stations in Taiwan. Results show that PM2.5,B concentrations measured by the VEREWA-F701 BAM (without federal equivalent method (FEM) designation) are consistently higher than PM2.5,D concentrations by 58.4 37.4% at Jhongshan station, while less overestimation exists at Sinjhuang and judong stations, which is 29.8 +/- 20.2 and 28.4 +/- 19.0%, respectively, where the earlier version of the Met-One BAM-1020s (without FEM designation) are used. Different factors influencing the overestimation, which include aerosol water content, volatilization of inorganic species and positive artifacts due to acid gas adsorption by the glass fiber filter tapes were studied for the BAM-1020. Results show that the overestimation is mainly caused by the positive artifacts due to acid gas adsorption by the glass fiber filter tapes used in the BAM-1020. Aerosol water content and volatilization loss of inorganic semi-volatile species are found to be less important to the overestimation. Crown Copyright (C) 2013 Published by Elsevier Ltd. All rights reserved.
Ultrafine Particles and PM2.5 at Three Urban Air Monitoring Stations in Northern Taiwan from 2011 to 2013
(2015-11-01)
Lin, Guan-Yu
;
Lee, Guo-Rui
;
Lin, Sih-Fan
;
Hung, Yi-Hung
;
Li, Shih-Wei
In this study, long term measurements of PM2.5 and ultrafine particles (UFPs) for daily average mass concentration at Zhongshan (ZS), Sinjhuang (SJ), and Jhudong (JD) urban air monitoring stations were conducted from 2011 spring to 2013 autumn. The results showed that daily average UFPs mass concentrations in spring (average at 3 stations: 1.58 +/- 0.74 mu g m(-3)) and summer (average at 3 stations: 1.59 +/- 0.53 mu g m(-3)) were higher than those in autumn (average at 3 stations: 1.02 +/- 0.28 mu g m(-3)) and winter (average at 3 stations: 1.04 +/- 0.48 mu g m(-3)) due to the impacts by heavy traffic emission and new particle formation event. The effective density (rho(eff)) and dynamic shape factor (chi) for ultrafine particles (UFPs) were found to be 0.68 +/- 0.16 g cm(-3) and 2.06 +/- 0.19, respectively, suggesting that the particle morphology was irregular shape. Based on the calculated rho(eff) and chi, the average number and surface area concentration ratio of UFPs to those of PM2.5 at these monitoring stations was determined to be 89.0 +/- 5.5% and 42.1 +/- 12.8%, respectively, suggesting that UFPs contribute significantly to the health-relevant PM2.5 aerosol fraction in these stations.