Bubble Size Distribution Dependence on Liquid Viscosity and Gas Flowrate Within a Bubble Column With a Porous Sparger

Abstract

Bubble size distributions within the homogeneous and heterogeneous regimes were experimentally investigated with varying gas superficial velocity and viscosity. Air was bubbled into aqueous solutions of glycerin (concentrations from 0% to 85%) through a porous stone sparger. A minimum of 2400 bubbles were measured per operating condition. The probability density functions were shown to be near Gaussian (normal) and lognormal for the homogeneous and heterogeneous regimes, respectively. Deviations from these distributions were observed at the bubble size extrema. The skewness and kurtosis were used to determine the operation regime and further analyzed. The homogeneous results showed excellent agreement with a power-law correlation for initial bubble sizes with only slight modifications to the constant and exponent, even though extrapolation over two orders of magnitude was required for the comparison. A dimensionally reasoned scaling law for bubbles in the heterogeneous regime was formed following similar logic to classic work analyzing the breakage of droplets within isotropic turbulence. Once again, the current results were in excellent agreement with slight modifications to the proportionality constant and exponent.