Browsing by Author "Hsu, YD"

Now showing 1 - 2 of 2

Axial flow cyclone for segregation and collection of ultrafine particles: Theoretical and experimental study
(2005-03-01)
Hsu, YD
;
Chein, HM
;
Chen, TM
;
Tsai, CJ
;
環境工程研究所
In this study, an axial flow cyclone was designed, fabricated, and evaluated at different conditions of air flow rates (Q(0)) and low-pressure environments (P), especially for the segregation and collection of ultrafine particles. An evaporation/condensation type of aerosol generation system consisting of tube furnace and mixing chamber was employed to produce test aerosols. The test aerosol was then classified by a differential mobility analyzer (DMA) and number concentration was measured by a condensation nuclei counter (CNC) and an electrometer upstream and downstream of the cyclone, respectively. The s-shaped curve of the collection efficiency in submicron particle size range was obtained to be similar to the traditional cyclone found in the literatures when the particles were largerthan 40 nm at Q(0) = 1.07, 0.455 L(STP)/min, and P= 4.8-500 Torr. The curve was found to be fitted very well by a serniempirical equation described in this paper. Forparticles smaller than 40 nm, however, the collection efficiency was unusually increased as the particle diameter was decreased due to the fact that the diffusion deposition becomes the dominant collection mechanism in the low pressure conditions. A model composed of centrifugal force and diffusion deposition is presented and used to fit the experimental data. The cyclone was demonstrated to separate and collect ultrafine particles effectively in the tested vacuum conditions.
Theoretical and experimental study of an axial flow cyclone for fine particle removal in vacuum conditions
(2004-09-01)
Tsai, CJ
;
Chen, DR
;
Chein, HM
;
Chen, SC
;
Roth, JL
An axial flow cyclone to remove fine particles at low pressure conditions (6-23 torr) was designed and tested. The inner diameter of the cyclone is 3.0 cm and tested flow rates are 0.455 and 1.0 slpm. A theoretical evaluation was first carried out to calculate the particle collection efficiency and cutoff diameter for the axial flow cyclone. Experiments were then conducted to test the theory at different flow rates, pressures and cyclone designs. It was demonstrated that at sufficiently low pressure of 6 torr (flow rate = 0.455 slpm), the axial flow cyclone is able to remove particles below 100 nm efficiently, and the flow Reynolds number was found to have a great effect on the particle collection efficiency. (C) 2004 Elsevier Ltd. All rights reserved.