Development of a Cyclone-Based Aerosol Sampler with Recirculating Liquid Film: Theory and Experiment

Figures & data

FIG. 1 Schematic diagram of a sampler with recirculating liquid film. H_C is the actual cyclone height; H is the cyclone height measured from the nozzle axis; R is the radius of the cyclone; r_c is the distance between the cyclone center axis and the nozzle axis; and r_B is the vortex radius.

FIG. 2 The results of calculation of average trajectory of airflow lines in the swirling cyclone.

FIG. 3 The results of calculation of F(z/HB) function and its derivative.

FIG. 4 Particle capturing efficiency in the swirling cyclone calculated under (a) different cyclone diameter 2R (Q = 60 l/min) and (b) different airflow rate Q (2R = 20 mm). Cyclone height H is 50 mm and nozzle diameter is 4 mm.

FIG. 5 Differential efficiency of particle capturing in the swirling cyclone calculated under (a) different particle sizes d _p (Q = 60 l/min) and (b) different airflow rates Q (d _p = 1 μm). Cyclone height H is 50 mm and diameter is 20 mm. Nozzle diameter is 4 mm.

FIG. 6 Photograph of a typical swirling sampler with recirculating water film.

FIG. 7 (a) Schematic diagram of the setup for different experiments; (b) Top-view of points for pressure measurements using a mobile sonde connected to mP1.

TABLE 1 Pressure evaluation with mobile sonde near swirling cyclone wall

	Pressure, Pa
Distance from nozzle axis, mm	Point 1	Point 2	Point 3	Point 4
45	200	150	120	160
40	120	10	95	120
35	50	−25	110	100
30	−80	50	80	150
25	−85	100	100	20
20	−45	10	160	−120
15	−30	−10	100	−120
10	−60	50	−100	−40
5	−170	450	−100	−90
0	−200	300	−270	−50
−5	−330	−550	−500	200
−7.5	420	300	−500	−420

TABLE 2 Pressure evaluation on 1–3 and 2–4 profiles depending on sonde distance from cyclone wall

	Pressure distribution on profiles (1–3)							Pressure distribution on profiles (2–4)
	Sonde coordinate from point 1, mm							Sonde coordinate from point 2, mm
Height from nozzle axis, mm	0	1	2	10	18	19	20	0	1	2	10	18	19	20
	(center)							(center)
	Pressure, Pa							Pressure, Pa
45	200	50	0	−60	0	40	120	150	40	0	−60	0	40	160
30	−80	−95	−100	−100	0	20	80	50	20	0	−100	0	40	150
15	−30	−*	—	−125	0	30	100	−10	—	—	−125	—	—	−120
0	−200	—	—	−120	0	—	−270	300	60	0	−120	—	—	−50

FIG. 8 Airflow positive pressure area borders constructed by Table 1 data.

FIG. 9 Relationship of flow rate and static pressure measured on the cyclone wall at the height of 15 and 30 mm.

TABLE 3 Maximal water-film heights for cyclones of various design and operating parameters. Both the cyclone height and the maximal height of the water film were distances from the bottom of the cyclone

Parameters	Values
Cyclone diameter, mm	16	20	24
Nozzle diameter, mm	4	4	4
Cyclone height, mm	55	55	55
Air flow rates that provide stable recirculating water film, l/min	37 ± 5	48 ± 3	53 ± 4
Maximal liquid-film height, mm, calculated from Equation (18)*	45	56	53

TABLE 4 Comparison of maximal liquid-film heights between measurements using soldered-in sonde tubes and predictions calculated from Equation (18). Swirling cyclone has the dimension of diameter 20 mm, height 55 mm, nozzle 2 × 6 mm

Air flow rate (l/min)	40	50	60
Maximal liquid-film pressure (in mm H2O) calculated by Equation (18)	31.8	50.3	72.9
Liquid height in tube z = 15 mm (experiment)	13	32	41
Maximal liquid rise based on the tube z = 15 mm (experiment)	28	47	55*
Liquid height in tube z = 30 mm (experiment)	2	17	26
Maximal liquid rise based on the tube z = 30 mm (experiment)	32	47	55*

FIG. 10 The imprint of stained particles settling in the swirling cyclone using a rectangular nozzle. Note that the cut around the nozzle causes the missing sections in the imprints. (Cyclone diameter is 20 mm, height is 55 mm, nozzle dimension is 2 × 6 mm. Air consumption is 80 l/min.).

FIG. 11 The imprint of stained particles settling in the swirling cyclone using a circular nozzle. Note that the cut around the nozzle causes the missing sections in the imprints. (Cyclone diameter is 20 mm, cyclone height is 55 mm, nozzle diameter is 4 mm, and air consumption is 80 l/min.).

FIG. 12 Capturing efficiencies of monodisperse latex particles in the swirling sampler. The data points were experimentally obtained and the curve was theoretically calculated using Equation (30).