Browsing by Author "Shiau, HG"

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Effect of deposited particles and particle charge on the penetration of small sampling cyclones
(1999-03-01)
Tsai, CJ
;
Shiau, HG
;
Lin, KC
;
Shih, TS
;
環境工程研究所
Effects of particle mass deposited in the cyclone and particle electrostatic charge on the particle penetration of the commonly used 10mm nylon cyclone have been experimentally investigated in this study. The solid particle penetration of the cyclone has been found to decrease with an increase in particle mass deposited in the cyclone. This effect is most significant for particles near the cutoff aerodynamic diameter and when the deposited particle mass is low. The penetration of the cyclone has also been found to be influenced by particle electrostatic charge. This effect is also significant for particles near the cutoff aerodynamic diameter and when the number of elementary units of charge is greater than several thousands. To overcome these problems, a new cyclone made of conductive aluminum and with inner diameter nearly twice that of the 10 mm nylon cyclone has been designed and tested. Experimental results indicate that effects of both deposited particle mass as well as electrostatic charge on the penetration are reduced substantially in this cyclone. (C) 1999 Elsevier Science Ltd. All rights reserved.
Field study of the accuracy of two respirable sampling cyclones
(1999-12-01)
Tsai, CJ
;
Shiau, HG
;
Shih, TS
;
環境工程研究所
;
Institute of Environmental Engineering
This study is to evaluate the sampling bias of a new cyclone (Tsai et al. 1999) and a 10 mm nylon cyclone under field sampling conditions. Both cyclones were operated at the optimum flow rate of 1.7 L/min. The Marple personal cascade impactor was used to measure the particle size distributions, which were used to calculate the reference RPM (Respirable Particulate Matter) concentrations according to the new ACGIH criteria. A wind tunnel was used in the field to ensure uniform particle concentration and wind speed across the tested cyclones and impactors in the working section. The wind speed, which was varied from 0.8 to 2.3 m/s, was kept constant in the wind tunnel. Near the packaging area of a glazing-making factory (mass median aerodynamic diameter, or MMAD: 11.1 mu m), the average ratio of the RPM concentrations measured by the cyclones to the standard RPM concentrations was found to be 1.20 and 1.10 for the 10 mm nylon and the new cyclone, respectively. Near the packaging area of a lead powder factory (MMAD: 4.82 mu m), the average ratio of the RPM measured by the cyclones to the reference RPM was found to be 1.13 and 1.02 for the 10 mm nylon and the new cyclone, respectively. Wind speed and total airborne particle concentration were found to have little effect on the accuracy of the two respirable cyclones. This field study showed that the new cyclone is more accurate than the 10 mm nylon cyclone based on the reference RPM.