Browsing by Author "Bayissa, Tamiru"

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    Radon Progeny Deposition in Respiratory Tract: Comparative Analysis of Models
    (Addis Ababa University, 2011-07) Bayissa, Tamiru; Tesfaye, Tilahun (PhD)
    Cheng (2003) model of the extra-thoracic respiratory tract was used to calculate the deposition efficiency of aerosols of aerodynamic diameter ranging from 0.1 m to 72 m. The model assumes the deposition in the extra-thoracic region is mainly due to nasal airway geometry and the critical dimension is the minimum crosssectional area in the nasal passage. A dimensionless Stokes number is calculated as a function of the the aerodynamic diameter (da), flow rate (Q), and the minimum cross-sectional area (Amin). Literature value of Amin = 1:61 cm2 was used in the calculation of Stockes number. The calculation done using this model agrees with the predictions of the ICRP 1994 respiratory tract model. Further this model gives good agreement to the experimental results available in literature by introducing adjusting parameters for breathing rate and specific geometries of individuals