Effects of Physicochemical Properties of Ultrafine Particles on the Performance of an Ultrafine Particle Concentrator

Figures & data

FIG. 1 The Harvard Ultrafine Concentrated Ambient Particle System (HUCAPS).

FIG. 2 Experimental setup for laboratory performance evaluation of HUCAPS.

TABLE 1 Salient features of different aerosols used to challenge the HUCAPS

		Aerosol mobility diameter
Aerosol composition	Deliquescence relative humidity* (%)	Mean (nm)	Median (nm)	Mode (nm)	Geometric standard deviation	Typical upstream aerosol concentrations (#/cc)
Ammonium sulphate	81	66± 0.5	58± 0.5	53± 0.5	1.6± 0.1	2150± 30 (n = 5)
Sodium chloride	75	60± 0.5	43± 0.5	50± 0.5	1.6± 0.1	3050± 50 (n = 5)
Potassium sulphate	97	58± 0.5	48± 0.5	43± 0.5	1.6± 0.1	1980± 30 (n = 5)
Polystyrene latex	—	63± 0.5	60± 0.5	62± 0.5	1.8± 0.1	1120± 10 (n = 5)

TABLE 2 Effect of saturation ratio on the concentration enrichment factor as a function of aerosol hygroscopicity

	Concentration enrichment factor* (calculated from aerosol number concentration)
Saturation ratio	Ammonium sulphate	Sodium chloride	Potassium sulphate	Indoor air	Polystyrene latex
1.8	0.9± 0.1	0.8± 0.1	0.9± 0.1	0.9± 0.1	0.9± 0.1
2.2	1.9± 0.1	1.6± 0.1	1.1± 0.1	1.2± 0.1	1.0± 0.1
2.5	8.0± 0.2	7.8± 0.2	5.2± 0.2	3.8± 0.2	2.3± 0.2
2.8	30.1± 3.0	30.4± 1.0	24.8± 1.0	23.4± 1.0	22.3± 1.0
3.0	45± 3.0	42± 3.0	39± 3.0	38± 3.0	36± 3.0

FIG. 3 Concentration enrichment factor as a function of saturation ratio.

FIG. 4 Concentration enrichment factors as a function of aerosol hygroscopicity.

TABLE 3 Results from filter reflectance analysis for BC on the aerosol mass collected

Filter type	Sampling duration (h)	Aerosol mass collected (μg)	CEFmass	Absorption coefficient (m^−1× 10^−5)	Estimated elemental carbon mass (μg)	CEFEC
Upstream	20	26	37.8	0.02	0.7	42.3
Downstream	20	982		1.64	29.6
Upstream	24	38	35.6	0.02	0.9	42.2
Downstream	24	1351		1.76	38.0
Upstream	24	37	33.8	0.02	0.9	37.9
Downstream	24	1249		1.58	34.1
Upstream	24	40	35.6	0.04	1.7	33.0
Downstream	24	1422		2.60	56.1

FIG. 5 Performance of HUCAPS with indoor air (Sr = 3.0).