Digital Twinning Process for Stirred Tank Reactors/Separation Unit Operations through Tandem Experimental/Computational Fluid Dynamics (CFD) Simulations

Abstract

Computational fluid dynamics simulations (CFD) were used to evaluate mixing in baffled and unbaffled vessels. The Reynolds-averaged Navier−Stokes k–ε model was implemented in OpenFOAM for obtaining the fluid flow field. The 95% homogenization times were determined by tracer tests. Experimental tests were conducted by injecting sodium chloride into the vessel and measuring the conductivity with two conductivity probes, while the simulations replicated the experimental conditions with the calculation of the transport of species. It was found that the geometry of the system had a great effect on the mixing time, since the irregular flow distribution, which can be obtained with baffles, can lead to local stagnation zones, which will increase the time needed to achieve the homogenization of the solute. It was also found that measuring local, pointwise concentrations can lead to a high underestimation of the global mixing time required for the homogenization of the entire vessel. Dissolution of sucrose was also studied experimentally and by mathematical modeling. The dissolution of sucrose was found to be kinetically limited and a very good agreement was found between the experiments and the modeling approach. The extent of the applicability of CFD simulations was evaluated for enabling rapid process design via simulations.

Hybrid Approach for Mixing Time Characterization and Scale-Up in Geometrical Nonsimilar Stirred Vessels Equipped with Eccentric Multi-Impeller Systems—An Industrial Perspective

“…Due to the large number of conducted experiments, data analysis was performed with an automated script written in Python. The offset-corrected signal of the step input experiments shows overall good reproducibility and follows trends from the literature [30,34,35]. The step height for all replicates is comparable.…”

“…Sensors with fast response times (optimally 5 times faster than measured mixing time) and measurement frequency of at least once per second are recommended [33]. When applying the approach of the global determination of mixing time, a representative sensor position must be chosen [34], and a sufficient number of replicates has to be considered [35,36]. To avoid the handling of large amounts of hazardous material, e.g., concentrated acids and bases, sodium chloride and sensitive conductivity sensors are often used in mixing time studies.…”

Digital Twin for the Prediction of Extreme Loads on a Wave Energy Conversion System

“…This last component means that the virtual model is fed with data obtained from the physical product, while the information and processes from the virtual representation are the input to the physical. As stated by [20], in many sectors, there is a need to build approaches that will help not only in the initial stages of the design process of a product but also during the operation phase [21]. While in the initial phase, numerical simulation tools and lab-scale experiments are necessary; in the operational phase, the availability of real data bring advancements in the monitoring and improving operations during the life cycle of a product.…”

Recursive Settling of Particles in Shear Thinning Polymer Solutions: Two Velocity Mathematical Model

“…It should be noted that, based on one-velocity continuum models, the existing tools of computational fluid dynamics make it possible to solve sedimentation problems, taking into account many complex processes. It is worth mentioning the works [ 7 , 8 , 9 ], where the sedimentation of particles in stirred vessels is analyzed in the case of two-phase turbulent mixing flows, taking into account chemical reactions, crystallization, and dissolution processes.…”