Prediction of Reaeration Rates in Square, Stirred Tanks
Publication: Journal of Environmental Engineering
Volume 125, Issue 3
Abstract
Experiments were conducted on the oxygen transfer coefficient, kLa20, through surface aeration in geometrically similar square tanks, with a rotor of diameter D fitted with six flat blades. An optimal geometric similarity of various linear dimensions, which produced maximum kLa20 for any rotational speed of rotor N by an earlier study, was maintained. A simulation equation uniquely correlating k = kLa20(ν/g2)1/3 (ν and g are kinematic viscosity of water and gravitational constant, respectively), and a parameter governing the theoretical power per unit volume, X = N3D2/(g4/3ν1/3), is developed. Such a simulation equation can be used to predict maximum k for any N in any size of such geometrically similar square tanks. An example illustrating the application of results is presented. Also, it has been established that neither the Reynolds criterion nor the Froude criterion is singularly valid to simulate either k or K = kLa20/N, simultaneously in all the sizes of tanks, even through they are geometrically similar. Occurrence of “scale effects” due to the Reynolds and the Froude laws of similitude on both k and K are also evaluated.
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Information & Authors
Information
Published In
Journal of Environmental Engineering
Volume 125 • Issue 3 • March 1999
Pages: 215 - 223
History
Received: Feb 23, 1998
Published online: Mar 1, 1999
Published in print: Mar 1999
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