Investigation of Breakup and Coalescence Models for Churn-Turbulent Gas-Liquid Bubble Columns

Abstract

Three-dimensional Eulerian-Eulerian transient simulations were conducted to represent the gas-liquid flow of a heterogeneous bubble column. Different drag closures, breakup and coalescence models were evaluated in order to verify their influence on the model prediction. Numerical simulations were compared to experimental data, with industrial conditions of gas superficial velocities: 20cm/s and 40cm/s, in order to select the most suitable models to describe the bubble’ dynamics in the heterogeneous flow. The standard k − ε model for both phases was set for turbulence. 12 combinations of breakup and coalescence models were compared and analyzed. In the case of coalescence, Models of Prince and Blanch, and Luo presented similar behavior and good agreement with experimental data, while for breakup, a breakage forming three daughter bubbles appeared to be the best choice. Simulations presented relative errors around 7.7% and 14.0%, for 20cm/s and 40cm/s respectively, for the gas axial velocity, and around 14% and 21.9%, for gas holdup. For drag force, density and viscosity were accounted by an average of the phases, which resulted in an improvement about 7% on model validation

Keywords

• cfd simulation; population balance; breakup; coalescence; churn turbulent flow.