TURBULENT MASS-TRANSFER IN SMALL RADIUS RATIO ANNULI

Mass transfer in annuli for both fully developed laminar and turbulent flow conditions has been studied with respect to available experiment al data. It is shown that prediction of the Sherwood number for the in ner annular wall based on the hypothesis of coincidence of the zero sh ear stress position for laminar and turbulent flows leads to serious e rror in the case of small radius ratio. Also it is shown that in contr ast with plain tubes the curvature in small radius ratio annuli should be taken into account for the case of small Reynolds numbers. In cons equence, the well-known Leveque equation can be used for the calculati on of the mass transfer coefficient in annuli only under certain condi tions. Possibilities of electrodiffusion diagnostics for the precise d etermination of the zero shear stress position in annuli are discussed .