Browsing by Author "Karasev, Vladimir V."

Now showing 1 - 2 of 2

Laboratory and field tests of a novel three-stage personal dust sampler for sampling three dust fractions simultaneously
(2008-01-01)
Tsai, Chuen-Jinn
;
Chang, Cheng-Sheng
;
Chen, Sheng-Chieh
;
Chen, Penny
;
Shih, Tung-Sheng
This study designed and calibrated a novel three-stage personal dust sampler for sampling inhalable, thoracic, and respirable dust fractions simultaneously. The sampler has an annular inlet as the first stage for inhalable dust sampling, two impactors in the second and third stages to classify thoracic and respirable dusts, respectively, and a final filter. Laboratory calibration tests using monodisperse liquid and solid particles showed that with 100 ppi (pores per inch) PUF (porous polyurethane foam) substrates and at the flow rate of 3.2 L/min, the sampling efficiency curves of both impactor stages matched with the ISO/CEN/ACGIH thoracic and respirable sampling criteria, respectively. The sampler also agreed with the inhalable criterion for particles smaller than 17 mu m while the deviation increases with increasing particle diameter with a maximum of 28% for 27 mu m particles. It was also found that collection efficiency curve for solid particles was similar to that of liquid particles, indicating that there was no solid particle bounce from the PUF substrates for both impactors. This study also compared inhalable, thoracic, and respirable dust concentrations measured by the present three-stage personal dust samplers with those of the Respicon samplers at three different workplaces. Without using a correction factor of 1.5 for the extrathoracic dusts of the Respicon, field results showed that the present three-stage sampler measured three dust fractions comparable to those of the Respicon samplers. The inhalable dust concentrations of the two samplers differed within 5% while the thoracic and respirable concentration differed by less than 22%.
Particle loss in a critical orifice
(2007-09-01)
Chen, Sheng-Chieh
;
Tsai, Chuen-Jinn
;
Wu, Cheng-Han
;
Pui, David Y. . H.
;
Onischuk, Andrei A.
Particle deposition in different regions of a critical orifice assembly was studied numerically and experimentally. The investigated orifice is an O'Keefe E-9 (O'Keefe Control Co.) orifice whose diameter is 0.231 mm and critical flow rate is 0.455 slpm. The orifice assembly has an inlet tube (inner diameter = 10.4 mm, length = 90 mm) and outlet tube (inner diameter = 6.2 mm, length = 60 mm). In the numerical study, axisymmetric, laminar flow field of the orifice assembly was obtained first by solving the Navier-Stokes equations. The diffusion loss of nanoparticles was then calculated by solving the convection-diffusion equation. Inertial impaction and interception loss of 2-10 mu m particles was calculated by tracing particle trajectories in the flow field. In the experimental study, monodisperse NaCl (20-800 nm in aerodynamic diameter) and fluorescein-containing oleic acid (2-10 mu m in aerodynamic diameter) particles were used to test particle loss in both diffusion- and inertial impaction-dominated regimes. The numerical results were compared with the experimental data and good agreement was obtained with the maximum deviation smaller than 10.4%. (C) 2007 Elsevier Ltd. All rights reserved.