@article{SchwarzOrtlerLindner2024, author = {Schwarz, Benedikt and Ortler, Matthias and Lindner, Johannes}, title = {Rotational speed change and reverse mixing to avoid baffles in dispersing processes}, series = {Chemical Engineering Research and Design}, volume = {206}, journal = {Chemical Engineering Research and Design}, doi = {10.1016/j.cherd.2024.05.004}, pages = {302 -- 309}, year = {2024}, abstract = {Stirring is used for mass and heat transfer, particle suspending or similar processes. It is commonly conducted in a steady operation mode. This paper targets on performing the stirring process dynamically by reversing the rotation direction to introduce additional turbulences and hence accelerating the dispersing processes. The power introduced into the fluid as well as mixing kinetics performing dynamic mixing were studied based on the rotational acceleration, blade pitch angle, liquid volume and duration of the rotational speed direction interval for a vessel equipped with a turbine agitator with and without baffles. Experiments show that baffles are not necessary if reverse mixing is performed at a specific frequency.}, language = {en} } @inproceedings{SchwarzLindner2025, author = {Schwarz, Benedikt and Lindner, Johannes}, title = {Automated Process Optimization in Mixing with Adaptive and Dynamic Mixing Modes}, series = {PARTEC 2025}, booktitle = {PARTEC 2025}, year = {2025}, abstract = {Mixing plays a crucial role in industry, for e.g., fine and petrochemicals, food, pharmaceuticals, and mineral processing. The selection of the stirrer is based on the desired flow pattern and the rheological properties of the material being processed. A change in the mixing task or a significant shift in material properties during the process can lead to decreased efficiency, longer mixing times, or poorer mixing quality. To address the need for handling various tasks across a wide range of applications with the same mixer, a multi-purpose mixer with adjustable tools was developed. It consists of a coaxial stirrer with an inner and an outer stirrer. The blades of the inner stirrer can be changed in inclination during the process. This allows different tasks, such as dispersion, aeration, and suspension, to be performed efficiently in succession without the need for tool changes. Additionally, the process parameters can be dynamically changed to compensate for changes in the process. Energy input into the fluid serves as a key parameter to quantify the quality of a dispersion process. The three independent actuators can be used to achieve the best energy input. To identify the optimal settings, a control algorithm called the "automated design of experience" was developed. This algorithm adjusts the speed of the main and coaxial stirrers and the blade angle in a sequential manner, evaluating whether these changes lead to improved or worsened energy input. It is hence possible to determine optimum mixing parameters in an automated way.}, language = {en} } @misc{SchwarzLindner2025, author = {Schwarz, Benedikt and Lindner, Johannes}, title = {Variable volume flows in a hydrocyclone by changing the inlet geometry during the process}, series = {PARTEC 2025}, journal = {PARTEC 2025}, year = {2025}, abstract = {Motivation: Hydrocyclones are designed for a specific operating point but react badly to a change in operating conditions. Reducing the flow rate results in lower centrifugal forces and hence separation efficiency. Increasing the flow rate increases the pressure loss, while the separation efficiency suffers from increased turbulence. It is also not possible to react to modifications of the material or liquid phase to be separated. The aim of the present development is to create a cyclone that can react to variable operating parameters to keep the separation efficiency at a high level. Material \& Methodology: Good separation in cyclones requires a stable formation of the secondary vortex, which can be characterized by high tangential flow velocity (Schubert 2003). By implementing a variable cross-section in the inlet channel, the feeding velocity into the cyclone can be kept constant at changing flow rates to maintain the secondary vortex and keep comparable separation efficiency and pressure loss. An inline turbidity measurement at the upstream outlet can be used to monitor dynamically the separation efficiency. The variable cross-section area can be controlled depending on the fluctuating volume flow or on a specific outlet concentration based on the measured turbidity. Experiments showed that operating the system at a constant pressure loss improves the separation efficiency despite a reduction of the volume flow. Efficient separation at different or even fluctuating volume flow is hence possible.}, language = {en} } @inproceedings{SchwarzLindner2023, author = {Schwarz, Benedikt and Lindner, Johannes A.}, title = {Automatisierte Prozessoptimierung durch einen adaptiven, dynamischen Mischer}, series = {Jahrestreffen der DECHEMA-Fachgruppen Extraktion und Mischvorg{\"a}nge}, booktitle = {Jahrestreffen der DECHEMA-Fachgruppen Extraktion und Mischvorg{\"a}nge}, editor = {Dechema,}, year = {2023}, language = {en} } @inproceedings{SchwarzLindner2025, author = {Schwarz, Benedikt and Lindner, Johannes}, title = {Variabler Volumenstrom beim Hydrozyklon durch Ver{\"a}nderung der Einlaufgeometrie w{\"a}hrend des Prozesses}, series = {DECHEMA/VDI Fachgruppen Mechanische Fl{\"u}ssigkeitsabtrennung}, booktitle = {DECHEMA/VDI Fachgruppen Mechanische Fl{\"u}ssigkeitsabtrennung}, year = {2025}, language = {de} } @inproceedings{SchwarzLindner2025, author = {Schwarz, Benedikt and Lindner, Johannes}, title = {Verk{\"u}rzte Mischzeiten durch Reversieren der Drehrichtung in einem R{\"u}hrkessel}, series = {DECHEMA/VDI Fachgruppen Mischvorg{\"a}nge}, booktitle = {DECHEMA/VDI Fachgruppen Mischvorg{\"a}nge}, year = {2025}, language = {de} } @inproceedings{SchwarzLindner2024, author = {Schwarz, Benedikt and Lindner, Johannes}, title = {An approach to automated process optimization in mixing using adaptive and dynamic mixing modes}, series = {9 th Asian Particle Technology Symposium}, booktitle = {9 th Asian Particle Technology Symposium}, year = {2024}, language = {en} } @article{SchwarzKnieleLindner2025, author = {Schwarz, Benedikt and Kniele, H. and Lindner, Johannes}, title = {Automated Process Optimization in a Novel TripleShaft Mixer with Adaptive Mixing Modes}, series = {Chemie Ingenieur Technik}, journal = {Chemie Ingenieur Technik}, publisher = {Wiley-VCH}, address = {Weinheim}, doi = {10.1002/cite.70060}, year = {2025}, abstract = {A novel multi-purpose mixer was set up, which allows the change of the blade angle during the process and provides aflow field with respect to the needs of the mixing task. It features as well as a coaxial stirrer for highly viscous liquids andhence has three degrees of freedom. The stirrer considers the integration and validation of an optimization strategy forthe autonomous identification of an optimum operating point based on automated tests. The validation was conducted ina mixing process with several process input parameters, which is commonly used in industrial applications. The powerdraw of the main stirrer was used as a optimization parameter, representing the power used for dispersing. The speedand direction of the main and secondary stirrers, respectively, as well as the angle of the stirrer blades, were used as inputprocesses. The proposed control scheme automatically identifies and corrects drops in energy dissipation rates.}, language = {en} } @article{SchwarzKrauseLindner2026, author = {Schwarz, Benedikt and Krause, Peter and Lindner, Johannes}, title = {A Dynamic Hydrocyclone Adapting to Different Operating Points by Changing the Inlet Area}, series = {Chemical Engineering and Technology}, journal = {Chemical Engineering and Technology}, publisher = {Wiley-VCH}, address = {Weinheim}, doi = {10.1002/ceat.70154}, year = {2026}, abstract = {In this study, a novel hydrocyclone design was developed featuring a variable inlet geometry, which enables adjustment of the inlet area during operation. This allows control over the flow velocity within the cyclone, thereby maintaining a constant tangential velocity despite changes in volumetric flow rate. The prototype demonstrated a constant separation efficiency across a volumetric flow range spanning a factor of two between its minimum and maximum capacities. Two control strategies were investigated: operation at constant pressure drop and operation at constant inlet velocity, both under varying flow rates and inlet geometries. To initially examine the influence of key parameters, hydrocyclones with fixed geometries were fabricated using rapid prototyping and employed in experimental trials. These findings informed the subsequent development and construction of a dynamically adaptive steel prototype capable of dynamic geometrically adjustment.}, language = {en} }