Computational analysis of a vortex ingesting bioreactor for hydrogen production

Abstract

In this work, the fluid dynamics behaviour of a bioreactor specifically designed for a fermentative hydrogen production process is investigated by Computational Fluid Dynamics (CFD) simulations. The geometrical features of the bioreactor, which is a dual impellers baffled stirred tank provided with a draft tube, and the gas-liquid characteristics of the vortex ingesting operating mode make the modelling and the numerical solution tasks particularly challenging. The computational strategy is based on the two-phase formulation of the Reynolds Averaged Navier-Stokes equations in an Eulerian framework for both the continuous and the dispersed phase. The results of the simulations are compared with available experimental data collected in a parallel investigation under the same operating conditions and a identical bioreactor geometry. The reliability of the predicted overall hydrodynamics behaviour and the accuracy of the turbulent two-phase mean velocity field are evaluated and critically discussed. The results confirm that the proposed CFD approach is a suitable tool for the design and optimization of stirred bioreactors.