Axial dispersion and pressure drop for single-phase flow in annular pulsed disc and doughnut columns: A CFD study

Computational Fluid Dynamics (CFD) simulations have been performed to understand the effects of different operating and geometric parameters on axial dispersion and pressure drop for single-phase flow in annular pulsed disc and doughnut columns (APDDCs) which are relevant for spent nuclear fuel reprocessing. The first step of the two-step computational approach involves solution of Reynolds Averaged Navier-Stokes (RANS) equations with standard k-ε model of turbulence in 2D axisymmetric computational domain to obtain velocity and pressure fields. In the next step, dilute species transport equation is additionally solved to obtain residence time distribution (RTD) and axial dispersion coefficient. The computational approach has been validated by using experimental data of pulsed disc and doughnut columns (PDDCs) reported in literature. The validated computational approach has been used to perform parametric analysis to understand the effects of flow velocity, amplitude of pulsing, disc spacing, percen open area, the ratio of outer diameter and inner diameter of the annulus and flow cross-sectional area on pressure drop and axial dispersion coefficient.