Evaluation of large eddy simulation and Euler-Euler CFD models for solids flow dynamics in a stirred tank reactor

Mechanically agitated reactors find wide range of applications for solid suspension and mixing in the chemical, biochemical, and mineral processing industries. Understanding the solids dynamics in these reactors is necessary to improve the design and operation of such reactors. Computational fluid dynamic (CFD) models are often useful in this regard, as it can provide significant insights into the flow and mixing of the phases involved. However, the model predictions need extensive evaluation with experimental results before they can be confidently used for the scale-up and optimization of large scale reactors. Recently, Guha et al. carried out a systematic experimental investigation of the solids hydrodynamics in dense solid-liquid suspensions (2.5-19% solids loading w/w) in a stirred tank using the Computer Automated Radioactive Particle Tracking (CARPT) technique, which provided extensive information to efficiently assess the ability of the existing CFD models in predicting the solids dynamics in slurry reactors. This work presents such an evaluation by comparing the averaged solids velocities, turbulent kinetic energy, and solids sojourn time distributions predicted by CFD models with those obtained from the CARPT experiment for overall solids holdup of 1% (v/v) (2.5% w/w) at Reynolds number of 74,000. The Large Eddy Simulation (LES) and the Euler-Euler model are the models chosen for evaluation in the current study. (c) 2008 American Institute of Chemical Engineers.