Two-Phase CFD Study on Hydrodynamics in an Air-Pulsed Column Having Circular Slotted Plates: Influence of Slot Geometry

An Euler–Euler two-fluid numerical model is used in a two-dimensional (2D) axisymmetric CFD study. This study aims at predicting the dispersed-phase holdup in a 3 in. diameter air-pulsed column having circular slotted plates. The methodology involves numerically solving mass and momentum conservation equations for both the phases. The turbulence is modeled using the standard k–ε model based on mixture properties. The CFD model assumes monodispersed drops of the dispersed phase in the entire computational domain. The CFD model is validated with the reported experimental studies of an air-pulsed column having circular slotted plates as well as disc and doughnut plates. The effect of different drag models on the dispersed-phase holdup predicted in the column is reported. The Ishii–Zuber drag model is used in the CFD study as it provides good prediction of the dispersed-phase holdup. The validated model is also used to study the effects of geometrical parameters, namely the width of the slot, fractional opening area, and interplate spacing in the column, on dispersed-phase holdup using a response surface methodology. A 3-factor 3-level Box–Behnken design is used for the simulations, followed by ANOVA. The ANOVA results show that the most significant factor influencing the dispersed-phase holdup is the two-way interaction between interplate spacing and the fractional open area. Lastly, a comparison of hydrodynamics in a pulsed circular slotted plate column (PCrSPC) with a pulsed disc and doughnut column (PDDC) is reported. Large recirculation regions are formed in PDDC as compared to PCrSPC, leading to higher axial dispersion in PDDC.