Mass Transfer of Diffusive Species with Nonconstant In-Flight Formation and Removal in Laminar Tube Flow. Application to Unattached Short-Lived Radon Daughters
Résumé
This article deals with convective-diffusive aerosol transport with
in-flight formation and removal and is applied to the un attached fraction of
short-lived radon decay products. Two novel contributions to previous studies are
given in this numerical and experimental work: on the one hand, we solve the
mass-transport equations for all the short-lived radon daughters; on the other
hand, we include the 218Po neutralization into the mass-transport equation of the
first radon decay product. Concerning the mass-transfer of all short-lived radon
daughters, numerical calculations lead to the development of simple correlations
for the 214Pb and 214Bi penetration fractions. Those correlations can be used to
determine the diffusion coefficient of 214Pb and 214Bi using the 2-filter method. In
our experiments, a diffusion coefficient equal to 5 x 10- 6 m2/s is found for the
214Pb. Concerning the 218Po neutralization, better agreement is observed between
our numerical and experimental results when 218Po neutralization is taken into
account. These results confirm the neutralization rates found by Howard and
Strange (1994).
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