Modeling free surface gas transfer in agitated lab-scale bioreactors

A physics-based approach for modeling convective gas-liquid mass transfer across free surfaces in lab-scale agitated vessels is presented. This approach, which combines numerical modeling with semi-empirical turbulence theory, is validated across multiple operating scales and conditions. The findings show that, regardless of the mechanical action driving motion, free surface mass transfer rate in lab-scale systems is consistent with empirical relationships. The role and importance of free surface convective mass transfer in lab scale devices is also discussed. The computational approach is shown to be practical within the context of industrial analysis and design timescales.