An Analysis of Mixing Time Correlations Across a Wide Reynolds Number Range

Mixing time serves as an indicator of the time required for the entire tank, including poorly mixed regions, to become homogeneous. Correlation equations for mixing time based on this definition have been reported. However, in operations where rapid mixing of an introduced material is required—specifically, in cases where the uniform mixing time in well-mixed regions is critical—correlation equations for mixing time in these well-mixed regions are necessary.In this study, the concentration gradient (∇C), defined as the spatial gradient (∇) of concentration (C), was introduced as a key parameter to characterize mixing. The mixing time was redefined as the time required for ∇C to become uniform throughout the stirred tank. Based on this definition, a correlation equation for mixing time was derived from the convection-diffusion equation. The validity of the derived parameters was evaluated using experimental data. The proposed correlation effectively predicts mixing times across different flow conditions.