Evolution of Ultrafine Particle Size Distributions Following Indoor Episodic Releases: Relative Importance of Coagulation, Deposition and Ventilation
Dong H. Rim, Lance L. Wallace, Andrew K. Persily, Jung I. Choi
Indoor ultrafine particles (UFP, 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 vs. 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 on.. 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.
, Wallace, L.
, Persily, A.
and Choi, J.
Evolution of Ultrafine Particle Size Distributions Following Indoor Episodic Releases: Relative Importance of Coagulation, Deposition and Ventilation, Aerosol Science and Technology, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=909446
(Accessed March 3, 2024)