Abstract
The use of the turbulent eddy diffusion model and its variants in exposure assessment is limited due to the lack of knowledge regarding the isotropic eddy diffusion coefficient, D T . But some studies have suggested a possible relationship between D T and the air changes per hour (ACH) through a room. The main goal of this study was to accurately estimate D T for a range of ACH values by minimizing the difference between the concentrations measured and predicted by eddy diffusion model. We constructed an experimental chamber with a spatial concentration gradient away from the contaminant source, and conducted 27 3-hr long experiments using toluene and acetone under different air flow conditions (0.43–2.89 ACHs). An eddy diffusion model accounting for chamber boundary, general ventilation, and advection was developed. A mathematical expression for the slope based on the geometrical parameters of the ventilation system was also derived. There is a strong linear relationship between D T and ACH, providing a surrogate parameter for estimating D T in real-life settings. For the first time, a mathematical expression for the relationship between D T and ACH has been derived that also corrects for non-ideal conditions, and the calculated value of the slope between these two parameters is very close to the experimentally determined value. The values of D T obtained from the experiments are generally consistent with values reported in the literature. They are also independent of averaging time of measurements, allowing for comparison of values obtained from different measurement settings. These findings make the use of turbulent eddy diffusion models for exposure assessment in workplace/indoor environments more practical.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 195-206 |
| Number of pages | 12 |
| Journal | Journal of occupational and environmental hygiene |
| Volume | 14 |
| Issue number | 3 |
| DOIs | |
| State | Published - Mar 4 2017 |
Fingerprint
Keywords
- Diffusion model
- eddy diffusivity
- exposure assessment
- indoor air pollution
- turbulent eddy diffusion coefficient (D )
Cite this
Turbulent eddy diffusion models in exposure assessment - Determination of the eddy diffusion coefficient. / Shao, Yuan; Ramachandran, Sandhya; Arnold, Susan; Ramachandran, Gurumurthy.
In: Journal of occupational and environmental hygiene, Vol. 14, No. 3, 04.03.2017, p. 195-206.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Turbulent eddy diffusion models in exposure assessment - Determination of the eddy diffusion coefficient
AU - Shao, Yuan
AU - Ramachandran, Sandhya
AU - Arnold, Susan
AU - Ramachandran, Gurumurthy
PY - 2017/3/4
Y1 - 2017/3/4
N2 - The use of the turbulent eddy diffusion model and its variants in exposure assessment is limited due to the lack of knowledge regarding the isotropic eddy diffusion coefficient, D T . But some studies have suggested a possible relationship between D T and the air changes per hour (ACH) through a room. The main goal of this study was to accurately estimate D T for a range of ACH values by minimizing the difference between the concentrations measured and predicted by eddy diffusion model. We constructed an experimental chamber with a spatial concentration gradient away from the contaminant source, and conducted 27 3-hr long experiments using toluene and acetone under different air flow conditions (0.43–2.89 ACHs). An eddy diffusion model accounting for chamber boundary, general ventilation, and advection was developed. A mathematical expression for the slope based on the geometrical parameters of the ventilation system was also derived. There is a strong linear relationship between D T and ACH, providing a surrogate parameter for estimating D T in real-life settings. For the first time, a mathematical expression for the relationship between D T and ACH has been derived that also corrects for non-ideal conditions, and the calculated value of the slope between these two parameters is very close to the experimentally determined value. The values of D T obtained from the experiments are generally consistent with values reported in the literature. They are also independent of averaging time of measurements, allowing for comparison of values obtained from different measurement settings. These findings make the use of turbulent eddy diffusion models for exposure assessment in workplace/indoor environments more practical.
AB - The use of the turbulent eddy diffusion model and its variants in exposure assessment is limited due to the lack of knowledge regarding the isotropic eddy diffusion coefficient, D T . But some studies have suggested a possible relationship between D T and the air changes per hour (ACH) through a room. The main goal of this study was to accurately estimate D T for a range of ACH values by minimizing the difference between the concentrations measured and predicted by eddy diffusion model. We constructed an experimental chamber with a spatial concentration gradient away from the contaminant source, and conducted 27 3-hr long experiments using toluene and acetone under different air flow conditions (0.43–2.89 ACHs). An eddy diffusion model accounting for chamber boundary, general ventilation, and advection was developed. A mathematical expression for the slope based on the geometrical parameters of the ventilation system was also derived. There is a strong linear relationship between D T and ACH, providing a surrogate parameter for estimating D T in real-life settings. For the first time, a mathematical expression for the relationship between D T and ACH has been derived that also corrects for non-ideal conditions, and the calculated value of the slope between these two parameters is very close to the experimentally determined value. The values of D T obtained from the experiments are generally consistent with values reported in the literature. They are also independent of averaging time of measurements, allowing for comparison of values obtained from different measurement settings. These findings make the use of turbulent eddy diffusion models for exposure assessment in workplace/indoor environments more practical.
KW - Diffusion model
KW - eddy diffusivity
KW - exposure assessment
KW - indoor air pollution
KW - turbulent eddy diffusion coefficient (D )
UR - http://www.scopus.com/inward/record.url?scp=85011977661&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85011977661&partnerID=8YFLogxK
U2 - 10.1080/15459624.2016.1238476
DO - 10.1080/15459624.2016.1238476
M3 - Article
C2 - 27717291
AN - SCOPUS:85011977661
VL - 14
SP - 195
EP - 206
JO - Journal of Occupational and Environmental Hygiene
JF - Journal of Occupational and Environmental Hygiene
SN - 1545-9624
IS - 3
ER -