Comparison of measured gas flux with Drift Flux Theory in a two-phase counter-current flow channel

This experimental study aims to test the validity of the Drift Flux Theory (DFT) within a lab scale REFLUXTM Flotation Cell (RFCTM). The DFT, which is an analytical model, studies the transport conditions of rising bubbles in downward liquid flux. The model relates the component volumetric fluxes to the relative velocity between the liquid and gas phases and to their volume fractions. This requires measuring the local gas volume fraction and bubble diameter with high spatial and temporal resolution, which remains a challenge due to the limitations of existing sensors. To tackle this problem, newer sensors were used in the current study to revisit the hydrodynamics of the RFCTM. In the current experimental setup, the gas fraction is measured using the Wire-Mesh Sensor, which has a high spatial and temporal resolution of 0.5 mm and 10 kHz respectively. The bubble size distribution is measured in situ with an optical process microscope. The experimental parameters, such as gas flux, liquid flux, and wash-water fluxes, were changed to set different conditions in the model. These parameteric values were compared to predictions from the DFT which revealed significant deviations from the theoretical claims made on the basis of simplified transport conditions. The application of the drift-flux theory to highly turbulent multiphase flows, such as RFCTM, must therefore be reviewed and requires further research.