Browsing by Author "Chen, Tzu-Ming"

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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
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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.
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.