Evaporation of Liquid Semi-Volatile Aerosols Collected on Fibrous Filters

Figures & data

FIG. 1 Evaporation of collected ammonium nitrate on a TEOM filter for different masses. Experimental points taken from Furuuchi et al. 2001 and compared to the maximum theoretical evaporation rate noted “saturation.”

FIG. 2 Drops of n-hexadecane deposited on the quartz fibers of a W filter, observed by SEM. (a) axisymetric ondoloid drop in contact with only one fiber, (b) Clamshell shaped drop out of alignment with the bearing fiber, c) Drop deformed by simultaneous contact with several fibers.

FIG. 3 Diagram of the filter clogging system with mono- or poly-dispersed liquid aerosol.

TABLE 1 Size distribution of mono-dispersed aerosols of the C₁₆ tested

DMM (μ m)	σ g	Notation
1.48	1.26	1 μ m
4.43	1.26	4 μ m
7.64	1.14	7 μ m

FIG. 4 Diagram of the system for monitoring the evaporation of the liquid aerosols collected by the fibrous filter.

TABLE 2 Characteristics of the tested filters

		Glass
Material	Polyester				High-quality quartz
filter (notation)	T	D	B	A	W
Weight (g.m^− 2)	528	75	70	70	75
Thickness (mm)	1.72	0.58	0.60	0.65	0.40
Packing density	0.222	0.056	0.052	0.048	0.073
d f, Davies (μ m)	20.4	1.12	2.85	5.59	0.53
Δ p f (Pa) at 5 cm.s^− 1	40.9	299.2	46.4	21.5	580
K(m^2)	3.8 10^–11	1.7 10^–12	1.2 10^–11	2.7 10^–11	6.4 10^–13
Where d f,Davies is the diameter of the fibers determined by the Davies, 1973 model and K the permeability of the filters (m^2) defined by:
Where μ is the viscosity (Pa.s), e the thickness of the filter (m) and Δ p f the average load loss of filters (Pa) measured at v = 5 cm.s^–1.

FIG. 5 Evaporation of a mono-dispersed n-hexadecane aerosol, DMM = 1 μ m, Filter W, filtration velocity of 5 cm.s^{− 1} and a temperature of 23°C.

FIG. 6 Standardized maximum rate as a function of the mass of collected C₁₆, for all the tests. Group “W” includes results from W filters and group “other” includes all results obtained with filters A, B, D, and T.

FIG. 7 Mass of remaining aerosol at transition point t ₁ as a function of initial load M _ev,∞. M _ev,∞ ≥ 88 μ g and ε _a ≤ 40 μ g.

FIG. 8 Optical microscopic observations of W filters clogged with 1 mg n-hexadecane. (a) DMM = 1 μ m, (b) DMM = 7 μ m. Magnification ×200.

FIG. 9 Standardized evaporation rate as a function of residual mass at decreasing rate, for three tests (1, 2, and 3). W filter and DMM = 1 μ m. (a) M _ev,∞≈ 30 μg. (b) M _ev,∞≈ 90 μ g.