CFD analysis of diffuser configurations for enhanced oxygen transfer and flow mixing in two-phase reactor systems

Modeling mass transfer in gas-liquid systems is key to studying and optimizing multiple processes in nuclear reactor plants. Eulerian-Eulerian two-fluid approach has been widely used in CFD simulations to model gas-liquid phenomena for industrial applications. Although its coupling with mass transfer models can provide useful insights, a lack of studies remains concerning the modeling of medium to large size systems. In this work, two-phase CFD simulations of an aerated tank comprising 16 air diffusers have been performed and validated with experimental data to model oxygen transfer phenomena. Experimental void fraction data has been obtained with needle probe sensors located inside the tank at different heights. Simulations using open-source code OpenFOAM including the mass transfer through the two-film resistance theory and the oxygen transfer coefficient proposed by Clift have been done for two different diffuser configurations and two flow rates. Time-averaged void fraction profiles show an overall agreement for both configurations at the analyzed heights. Hydrodynamical differences generated by the diffuser layouts have been studied. Simulated oxygen curves capture the trend observed in experimental tests regarding oxygen transfer efficiency and saturation concentration.