Design and Validation of a 6-Volatility Tandem Differential Mobility Analyzer (VTDMA)

Figures & data

FIG. 1 Schematic view of the V-TDMA. 85 × 60 mm (300 × 300 DPI).

TABLE 1 Results of iterative calculations: T_i = oven utilization temperature, T_p = desired oven wall temperature, r_e = calculated oven outer radius, S = oven outer surface, V = oven volume, W = oven refractory weight

	T i (°C)	T p (°C)	r e (cm)	S (m^2)	V (m^3)	W (Kg)
Oven 2	200	50	4	0.085	1.5 × 10^−3	1.35
Oven 3	400	60	4	0.085	1.5 × 10^−3	1.35
Oven 4	600	65	5	0.11	2.3 × 10^−3	2.1
Oven 5	800	70	6	0.135	3.4 × 10^−3	3
Oven 6	1000	80	6	0.135	3.4 × 10^−3	3
Oven 1	100	40	3	0.062	8.5 × 10^−4	0.8

FIG 2 CFD temperature profile for Tamb = 25°C and Ti = 1000°C (oven heating path). 57 × 52 mm (300 × 300 DPI).

FIG 3 Measured temperature profile inside the heating path of the oven. 47 × 31 mm (300 × 300 DPI).

FIG 4.Results of NaCl penetration test showing the efficiency of aerosol transport through the Oven at 25°C and the VTDMA depending on the selected particle size and heater temperature (curves are deduced by fitting he measured dot raw data points). 58 × 44 mm (300 × 300 DPI).

CFD particle tracks and heating prediction for Dp = 100 nm and Ti = 800°C in the entrance (0 to 10 cm), the center (15 to 25 cm) and the cooling section (50 to 60 cm) of the thermo-desorber unit. 82 × 31 mm (300 × 300 DPI).

FIG 6.Inverted volatility scans of 100 nm NaCl laboratory generated aerosol heated stepwise. 48 × 30 mm (300 × 300 DPI).

FIG 7.Fraction of number and volume of particles lost by thermo-desorption as a function of conditioning temperatures. The curves are obtained from volatilization of NaCl particles with 100 nm initial size. 49 × 29 mm (300 × 300 DPI).

TABLE 2 Volatilization temperature of different test aerosols in the VTDMA

	O'Dowd	Philippin	Burtscher	Brooks	This work	This work
	(1993)	(1999)	(2000)	(2001)	(15 nm)	(150 nm)
(NH4)2SO4	280^ˆ	180^ˆ	180^ˆ	235^ˆ	160^ˆ	180^ˆ
NaCl	700^ˆ	—	—	650^ˆ	500^ˆ	650^ˆ
NaNO3	—	—	—	550^ˆ	475^ˆ	550^ˆ
NH4NO3	—	—	—	—	30^ˆ	60^ˆ

FIG 8.Volatility scan of 35 nm NaCl uncoated and coated size distributions. 48 × 31 mm (300 × 300 DPI).

FIG 9.Number (RN) and volume (RV) fractionation curves derived from volatility size distributions of initial 55 and 200 nm particles at the Puy de Dome Station as a function of conditioning temperatures. The slight increase at 100°C for 200 nm particles is due to instrumental error.