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Entry region mass transfer in turbulent pipe flow
Author(s) -
Wasan D. T.,
Jones W. O.,
Von Behren G. L.
Publication year - 1971
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.690170214
Subject(s) - mass transfer , turbulence , mass transfer coefficient , mechanics , schmidt number , thermodynamics , reynolds number , boundary layer , chemistry , diffusion , sherwood number , materials science , physics , nusselt number
A general treatment is presented for mass transfer in turbulent pipe flow with special emphasis on the mass transfer entry region and the role of interfacial velocity on the rate of mass transfer. This study includes numerical solutions of the convective diffusion equation with an entering fully developed flow. Solutions for constant properties and a constant wall boundary condition are presented over a wide range of Reynolds numbers, Schmidt numbers, and aspect ratios. An expression was developed for predicting the entry region mass transfer coefficient in both gaseous and liquid systems at ordinary fluxes with negligible interfacial velocities and at small aspect ratios. The proposed equation for a binary system is\documentclass{article}\pagestyle{empty}\begin{document}$$ N'St_{{\rm ave}} \, = \,0.24\,(N_{{\mathop{\rm Re}\nolimits} })^{ - 0.4} \,(N_{Sc})^{ - 2/3} \,(z/D)^{ - 0.3} $$\end{document}Experimental concentration profiles have been reported on the vaporization of acetone into a turbulent air stream within a short cylindrical test section. Data are also reported on concentration measurements in an air‐carbon dioxide gaseous mixture with a large interfacial velocity at the inner surface of a porous pipe test section. The numerical solutions of the diffusion convection equation have been compared with the experimental data in the mass transfer entry region, and a pronounced effect of the interfacial velocity on the mass transfer coefficient was found.