Novel Formulae for Deposition Efficiency of Electrically Neutral, Submicron Aerosol Particles in Bipolarly Charged Fibrous Filters Derived Using Brownian Dynamics Approach

Figures & data

FIG. 1 The influence of the fiber charge density, q _F , on the fractional single fiber efficiency calculated for the neutral and bipolarly charged fibers; U ₀ = 0.129 m/s, d _F = 7.84 μ m, and α = 0.069.

FIG. 2 Effect of the polarization force parameter (variable particle diameter) on the single fiber deposition efficiency due to electrostatic forces for q _F = 1 nC/m (left) and q _F = 5 nC/m (right).

FIG. 3 Effect of the polarization force parameter (variable fiber charge density) on the single fiber deposition efficiency due to electrostatic forces for d _P = 0.1 μ m (left) and d _P = 1 μ m (right).

FIG. 4 Collection of all numerical data (points) obtained using the BD method and comparison with individual fits to Equation (22) for fixed q _F values (thin dotted lines) and with global fits (two thick, solid and dashed lines, for various ranges of N _{σ 0} variability).

FIG. 5 (a) Effect of gas velocity (left) and (b) effect of fiber diameter (right) on the Δ E _el (N _{σ 0}) relationship.

TABLE 1 Characteristics of the respirator investigated experimentally by Bałazy et al. (2006)

Layer	Material	Thickness L [mm]	Fiber diameter d F [μ m]	Packing density α [−]	Basis weight ρ SF [g/m^2]
Outer	Polypropylene, neutral	0.31 ± 0.05	39.49 ± 1.80	0.165	46.67
Middle	Polypropylene, electret	1.77 ± 0.12	7.84 ± 2.00	0.069	110.67
Inner	Polypropylene, neutral	1.05 ± 0.16	40.88 ± 2.26	0.200	191.67

FIG. 6 Validation of the results of direct BD simulations using experimental data of Bałazy et al. (2006) obtained for a commercial respirator.

FIG. 7 Comparison of various correlations Δ E _el (N _{σ 0}) with experimental data of Kim et al. (2005) for an electrically active resin wool filter.

FIG. 8 Comparison of various correlations Δ E _el (N _{σ 0}) with experimental data of Lee et al. (2002) for a melt-blown polypropylene electret filter.

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Kim , J. C. , Otani , Y. , Namiki , N. and Kimura , K. 2005 . Initial Collection Performance of Resin Wool Filters and Estimation of Charge Density . Aerosol Sci. Technol. , 39 : 501 – 508 .

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Lee , M. , Otani , Y. , Namiki , N. and Emi , H. 2002 . Prediction of Collection Efficiency of High-performance Electret Filters . J. Chem. Engineering Japan , 35 ( 1 ) : 57 – 62 .

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