(319f) Micro-Scale Vof-CFD Model of Pressurized Air-Water Bubble Column: Effects of Bubble Flow Regime and Turbulence Model on Hydrodynamics
A micro-scale computational fluid dynamics (CFD) model was developed to investigate the hydrodynamics of the gas distributor under different flow regimes in an air-water bubble column operated at high pressure and ambient temperature. A three-dimensional volume-of-fluid (VOF) CFD model in a representative elementary volume (REV) of a region near a perforated plate distributor was constructed to capture the bubble size distribution (BSD) and hydrodynamics behaviours from injection nozzles. The turbulence models such as Reynolds-averaged NavierâStokes (RANS) and large eddy simulation (LES) approaches were tested in bubbling, transient and jetting regimes. It was found that the LES captured well the bubble behavior in the three flow regimes. Since the LES approach was time-consumming, the realizable k - Îµ model could be used for the bubbling regime to reduce the calculation time. The LES turbulence model was applied to all case studies to investigate the hydrodynamics in terms of BSD and mean bubble size (db,m) at the bottom of bubble columns. The BSD and db,m were compared with experimental data from the literature in air-water bubble columns at 0.1, 5 and 10 MPa. The micro-scale VOF-CFD model is an useful tool to predict the initial BSD from the gas distributor in bubble columns.