Theoretical Prediction of Volumetric Mass Transfer Coefficient (k_La) for Designing an Aeration Tank

Abstract

The objective of this present paper is to propose a new theoretical prediction method of the volumetric mass transfer coefficient (k_La) occurring in a gas-liquid contactor based on the dissociation of the liquid-side mass transfer coefficient (k_L) and the interfacial area (a). The calculated results have been compared with those obtained with the experimental process in a small-scale bubble column. Tap water was used as liquid phase and an elastic membrane with a single orifice as gas sparger. Only the dynamic bubble regime was considered in this work (Re_OR= 1501000 and We = 0.0024). This study has clearly shown that, whatever the operating conditions under test, the generated bubble diameters (dB), bubble frequency (f_B) and their associated rising velocities (U_B) were the important parameters in order to predict, not only the values of k_La, but also the values of a and of k_L. Moreover, these obtained results could provide a better understanding of the parameters which influence the oxygen transfer mechanism in the aeration process. By using the correlations to estimate these bubble hydrodynamics (d_B and U_B), it diminishes times for measuring the associated mass transfer parameters and also their experimental complexities and errors.