Penetration coefficient and deposition rate as a function of particle size in non-smoking naturally ventilated residences
Chao, C. Y. H., Wan, M. P. and Cheng, d. C. K.
2003 Atmospheric Environment, 37(30): 4233-4241
Chao, C. Y. H., Wan, M. P. and Cheng, d. C. K., (2003), "Penetration coefficient and deposition rate as a function of particle size in non-smoking naturally ventilated residences", Atmospheric Environment, 37(30): 4233-4241.
Abstract:
In residential environments without the operation of mechanical ventilation, in?ltration becomes the dominant ventilation mode and deposition on material surface is one of the major particle losses, while penetration determines how much ambient particle can be brought from outside into the indoor environment. This study presents results based on measurements conducted in six non-smoking residences in high-rise apartment buildings. The effect of particle size from 0.02 to 10 mm was evaluated. A simpli?ed indoor particle model was constructed to facilitate the calculation. The deposition rate and the penetration coef?cient were determined according to a decay rate constant and the steady-state particle concentration in the transient form of the indoor particle concentration decay pro?le. Both of them were particle-size dependent but showed a different up-and-down inversion pro?le against the particle size. The major causes of the depositional losses and the penetration effects are diffusion, inertial impaction/interception and settling. They reduce the penetration and enhance the deposition in the size ranges of ultra-?ne and coarse mode particles. The penetration coef?cient showed a hill-shape with respect to particle sizes and there was a peak (0.79) at the size range of 0.853-1.382 mm. It decreased on both smaller and larger particle size ranges and the minimum particle penetration coef?cient was 0.48 at the particle size range 4.698-9.647 mm. Deposition rate showed a converse shape with maximum values at both the smallest and the largest particle size ranges: 1.16104ms1 for 4.698-9.647 mm and 0.6104ms1 for 0.02-1.00 mm. The lowest deposition velocity was 0.31104ms1 (0.542-0.777 mm) that was about four times less than the maximum deposit ion velocity.
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