Evolution of ultrafine particle size distributions following indoor episodic releases: Relative importance of coagulation, deposition and ventilation

Donghyun Rim, Michal Green, Lance Wallace, Andrew Persily, Jung-il Choi

Research output: Contribution to journalArticle

42 Citations (Scopus)

Abstract

Indoor ultrafine particles (UFP, <100 nm) undergo aerosol processes such as coagulation and deposition, which alter UFP size distribution and accordingly the level of exposure to UFP of different sizes. This study investigates the decay of indoor UFP originated from five different sources: a gas stove and an electric stove, a candle, a hair dryer, and power tools in a residential test building. An indoor aerosol model was developed to investigate differential effects of coagulation, deposition, and ventilation. The coagulation model includes Brownian, van der Waals, and viscosity forces, and also fractal geometry for particles of >24 nm. The model was parameterized using different values of the Hamaker constant for predicting the coagulation rate. Deposition was determined for two different conditions: central fan on versus central fan off. For the case of a central fan running, deposition rates were measured by using a nonlinear solution to the mass balance equation for the whole building. For the central fan off case, an empirical model was used to estimate deposition rates. Ventilation was measured continuously using an automated tracer gas injection and sampling system. The study results show that coagulation is a significant aerosol process for UFP dynamics and the primary cause for the shift of particle size distribution following an episodic high-concentration UFP release with no fans operating. However, with the central mechanical fan on, UFP deposition loss is substantial and comparable to the coagulation loss. These results suggest that coagulation should be considered during high concentration periods (>20,000 cm -3), while particle deposition should be treated as a major loss mechanism when air recirculates through ductwork or mechanical systems.

Original languageEnglish
Pages (from-to)494-503
Number of pages10
JournalAerosol Science and Technology
Volume46
Issue number5
DOIs
Publication statusPublished - 2012 May 1

Fingerprint

Coagulation
Particle size analysis
coagulation
Fans
Ventilation
ventilation
particle size
Deposition rates
mass balance
Aerosols
tracer
Ultrafine
aerosol
Sampling
sampling
air
gas
loss
rate
Air

All Science Journal Classification (ASJC) codes

  • Environmental Chemistry
  • Materials Science(all)
  • Pollution

Cite this

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Evolution of ultrafine particle size distributions following indoor episodic releases : Relative importance of coagulation, deposition and ventilation. / Rim, Donghyun; Green, Michal; Wallace, Lance; Persily, Andrew; Choi, Jung-il.

In: Aerosol Science and Technology, Vol. 46, No. 5, 01.05.2012, p. 494-503.

Research output: Contribution to journalArticle

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