The effects on micromixing of co-feeding an inert gas with the bulk liquid are studied for a rotor–stator spinning disk reactor by means of the Villermaux–Dushman test reaction. The results of varying rotational speeds and gas–liquid ratios are reported for three configurations: injecting the acid into the dispersed region, into the bottom thin-film region, and into the upper thin-film region. The results show that injecting in the dispersed region is the optimal configuration, as the liquid experiences the shear stress between the rotor and the stator, and with increasing rotational speed, micromixing efficiency subsequently increases. Injecting in the thin-film regions leads to poor micromixing efficiency, since the gas layer reduces the turbulence levels experienced by the liquid. For the bottom thin film, increasing rotational speed improves micromixing efficiency due to inertial rotation of the liquid film. However, in the upper thin film, micromixing is significantly worse, being affected by the dripping of liquid on the stator at the injection point. Gas holdup measurements are compared to previous studies, showing that most of the gas volume is present in the thin-film regions. These results are relevant for the design of modular chemical processes using the spinning disk technology, when fast competitive chemical reactions occur in the presence of gas and liquid.
In this work, Computational Fluid Dynamics (CFD) are used to study the hydrodynamics in a complete rotor-statorspinning disc reactor (rs-SDR) with throughflow. Large Eddy Simulations (LES) of OpenFOAM 9 were used to capturethe turbulent structures of the flow in combination with the wall-adapting local eddy viscosity sub-grid-scale model(WALE). The method was validated based on residence time distributions (RTD) for a range of rotational Reynoldsnumbers (Re = wRD^2/v = 3.2 - 52 *10^4), a dimensionless flowrate (Cw = Q/v/RD ) of 150 and G = 0.0303 (G = h/RD ).The experimental RTD were obtained from tracer experiments with UV/VIS flow cells. From the RTD, the plug flow(PFR) volume fraction, the Péclet number and the radial position (rtrans) where the flow changes from PFR into ideallymixed (CSTR) were determined by using an engineering model based on axial dispersion. For the turbulent cases, goodagreement based on the RTD curve, PFR volume, Péclet number and rtrans were found. Furthermore, the boundarylayer thickness on the rotor and stator and the entrainment coefficient were in good agreement with literature. Lastly,the turbulent intensity was analyzed illustrating a high intensity at the rim of the rotor and 10% larger in centripetalflow compared to centrifugal flow.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.