A New Correlation for Predicting Aeration Efficiency for Air Diffused Systems

Abstract

Aeration efficiency is defined as the ratio of the oxygen transfer to the power consumed. It provides the best evaluation of the effectiveness of any aeration system. Most recent studies in oxygenation process focused on investigating the vital parameters affecting the oxygenation process without paying attention to the power consumption. The goal of this study is to establish an empirical correlation that describes aeration efficiency behavior with different orifice diameters. This work has two main parts: studying bubble hydrodynamics and aeration efficiency investigation. The first goal of examining bubble hydrodynamics was to calculate some necessary parameters that have a known effect on an aeration process. A second outcome from investigating bubble hydrodynamics was the development of two correlations for predicting bubble size and frequency with correlation factors of 0.95 and 0.92, respectively. In addition, the dimensionless analysis also was employed to correlate the parameters significantly affecting aeration efficiency. The new developed empirical formula was derived from 120 different experiments with a correlation factor of R^2=0.94 using SOLVER nonlinear regression in MS EXCEL. Five parameters were found to be affecting factors on the aeration performance, namely: Gas holdup, static to chamber pressure ratio, submergence height to tank diameter ratio, and aerated to tank area ratio. The parameter with the highest impact was the pressure ratio term, which has the largest power exponent of 0.721. Future work in this aspect will be implementing optimization techniques to find the best orifice size to be used in manufacturing aeration membranes.