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December 2018 - Merry Christmas and a Happy New Year

The eventful year 2018 is coming to an end. The Laboratory of Equipment Designs takes the opportunity to say goodbye to Sebastian Soboll and Felix Reichmann, who left the group this autumn, and wish them the best for their future. On the other hand, we would like to welcome again our new research associates Lukas Bittorf, Mira Schmalenberg, Jens Bobers, Julia Schuler and Julia Grühn, who will reinforce the team in the years to come. At the end of the year, we would like to thank our supporters, particularly the students who do research together with us and the alumni who always support us with advice. We wish you a Merry Christmas and a Happy New Year!


November 2018 - Superposition of Taylor and Dean vortices in coiled capillaries

Taylor and Dean flow are two flow patterns that enhance mass transfer and can be observed in capillaries. Recent studies have shown that a combination of these two plow patterns can lead to further increase of mass transfer. By utilizing a colorimetric method based on the consecutive oxidation of leuco-indigo carmine it is possible to visualize the superposition of Taylor and Dean vortices for a gas-liquid system. Depending on the flow conditions different flow regimes were identified that imply different intensities of the respective vortices. For one case a stratified gas distribution is observed, while the other case is characterized by a good radial distribution of dissolved gas within the liquid slug. In between a transition occurs that shows properties of both regimes. Further work will be dedicated to defining these transitions and describing the impact on the selectivity.

Contact: Waldemar Krieger


October 2018 – Investigation of liquid/liquid flows using Micro computed tomography (μ-CT)

For the examination of multiphase interfaces a non-invasive imaging technique is desirable. Micro computed tomography offers the possibility of the 3 dimensional representation of an object up to resolutions in the submicron range, even in opaque media. CT is based on the attenuation of X-Rays which is proportional to the density of the sample material, its atomic number and also the energy of the X-Rays used for the scan. Thus it is possible not only to gain information about the spatial extension of a single phase but much more to distinguish between different materials and thus information about the spatial extension of different multiphase interfaces. The current picture of the month shows a PTFE tube partially filled with silicone oil, water and air scanned with our Bruker Skyscan 1275.

Contact: Julia Schuler

bdm_10_2018_CT LL_flow

September 2018 - Reactive ion etching for microstructured devices

Reactive ion etching provides a dry etching mechanism, which leads to a highly precise and anisotropic etching behavior. A new manufacturing process for polyimide-based microstructured devices with low surface roughness was developed and applied on reactor geometry for liquid-liquid two-phase-flow. The geometry is evolved to create droplets via flow focusing as the dispersed phase is incised by two continuous phase inlet streams. The droplets are created, when the channel is widened from 100 µm to 300 µm. In order to keep the pressure loss for the developed reactor geometry as small as possible, the manufacturing process was optimized with a view to minimizing surface roughness by using Design of Experiments.

Contact: Jens Bobers


August 2018 - Gas-liquid mass transfer enhancement in micronozzles

Micronozzles can be used for the refinement of gas/liquid flow in order to reduce mass transport limitations. The interfacial area is increased due to the micronozzle induced bubble breakub. In this study, the mass transport coefficient was determined for a microchannel containing a micronozzle and a straight reference channel. For this, a colorimetric method based on the oxidation of dihydroresorufin was employed. Pictures were taken with a high speed camera. After image processing, fields of concentrations could be visualized using heat maps and quantified. A clear enhancement of mass transport using the micronozzle could be found.

Contact: Felix Reichmann

Reference channel: Taylor flow, 20 ml/min
Ref 20 mL_min (0,05 s)
Reference channel: Bubbly flow, 35 ml/min
Ref 35 mL_min (0,05 s)

Micronozzle: Laminar breakup, 80 ml/min
Laminarer Aufbruch 80 mL_min (0,0167 s)

Micronozzle: Turbulent breakup, 120 ml/min
Turbulenter Aufbruch 120 mL_min (0,01 s)

July 2018 - Micro–Computed Tomography (µ-CT)

Since June 2018, the Laboratory of Equipment Design has the opportunity of 3D-scanning by X-ray. The SkyScan 1275 from Bruker together with sophisticated analysis software enables clear 3D-images from various objects. A first test image was taken from a play figure, given with a cross sectional view of the polymer bodies. The Grand Smurf is composed of different parts such as the cap, head and body, or legs. Further investigations will include liquid slugs in capillaries or microfluidic chips.
Contact: Julia Schuler

June 2018 - Modular Coiled Flow Inverter Crystallizer (CFIC) 

Production of fine chemicals and pharmaceuticals often includes solid-liquid suspension flow. For continuous cooling a tubular crystallizer was designed based on the coiled flow inverter (CFI) concept, providing a narrow residence time distribution (RTD) of the liquid phase. Counter-current cooling in a tube-in-tube heat exchange concept was designed and allows an adjustment of the temperature profile. Successful operation of up to 50 g∙min-1 in a compact designed prototype with 4 mm inner diameter was scaled down to a modular CFI crystallizer (CFIC) with an inner diameter of 1.6 mm and varying length from 7.8 to 54.6 m. This leads to a significantly lower consumption of chemicals in process development with lower total mass flow rates of 15 – 20 g∙min-1. Due to modular design, mean residence time (3.8 to 6.9 min) and mean cooling rate (0.6 to 1.4 K∙min-1) can be varied at constant mass flow rate. Crystallization growth rate and yield are analyzed with the L-alanine/water test system and seed crystals of 125 – 180 µm. The next step is to characterize the CFIC in detail for different cooling rates, seed amount and seed crystal size. 

 Contact: Mira Schmalenberg

Corresponding publication: M. Schmalenberg, L. Hohmann, N. Kockmann. Miniaturized Tubular Cooling Crystallizer with Solid-Liquid Flow for Process Development. Conference Paper ASME- ICNMM2018, 10-13.06.2018, Dubrovnik Croatia, ICNMM2018-7660


May 2018 - Thin film resistance thermometer on polyimide foil for micro reactors

Besides the common benefits like enhanced mass and heat transfer, micro-structured reactors have drawbacks due to their micro-scaled structures. Measuring temperature is an important issue for micro process engineering. High solution, non-invasive measurement and robustness are requirements, which should be met by the measuring method.
Thin film technology combines the possibility to manufacture micro scaled structures with great flexibility in choosing material and geometry of the structures. Layers of aluminum with a thickness in nanometer scale are deposed on flexible polyimide foil and structured to obtain conductor tracks, which are used as temperature sensors.
The next step is combining a micro-structured reactor and temperature sensors on a single polyimide foil using reactive ion beam etching to create micro channels inside the polyimide foil.

Contact: Jens Bobers


April 2018 - Arduino based slider setup for bubble tracking in Taylor flow

Recently, low-cost hardware platforms such as Arduino have received increasing attention for equipment and process development. In this work, a vision sensor board (Pixy CMUcam5) is utilized to detect and track bubbles in gas-liquid Taylor flow. Information on the bubble position are processed by an Arduino microcontroller in order to motorize a slider setup that carries the Pixy cam and a DSLR camera. This setup allows for dynamic and automatic microfluidic investigations providing extensive insight into gas-liquid mass transfer and hydrodynamics.

Contact: Waldemar Krieger


March 2018 - Lab-scaled continuous operated spinning band column

Distillation as one of the oldest known separation techniques is widely used in chemical industry. Due to the upcoming change in the modern industry to flexible production with versatile modular plants, it is of high interest to develop continuous operating columns for laboratory scale. This is realized with a continuous operated spinning band column with low hold-up and low pressure drop but high separation efficiency as one possible module for modular plants.

For characterization purposes it is of interest to know the distribution of liquid droplets on the rotating spinning band and the mean residence time of liquid, flowing down the column. For first approaches, this can be conducted with dyed water. Hence, a mean residence time can be calculated for different rotation speeds as well as several feed flows and boiling rates.

Contact: Lukas Bittorf


February 2018 - Development of a surface-coated polymer plate reactor

In an effort to improve mechanical stability for an existing microreactor system made from PVDF-foils [1], a surface-coated microreactor was developed. Stability is provided by a PMMA polymer block, which serves as a base plate. Due to its optical transparency, PMMA allows for optical investigations of processes within the reactor. However, PMMA features little chemical resistance. Therefore, the PMMA plate is coated with a PVDF-foil of 100 µm in thickness. The coating and simultaneous structuring of the channel are carried out via ultrasonic hot embosssing and the sealing of the channel is realized by yet another PVDF-foil in an ultrasonic hot welding process step. The newly developed microreactor shows great results in terms of mixing behavior, residence time distribution and mechanical stability [2]. Application in a developed continuous reaction calorimeter employing highly exothermic chemical reactions showed promising results.

Contact: Felix Reichmann

Corresponding publication: [1] Tollkötter et al., Ultrasonic Hot Embossed Polymer Microreactors for Optical Measurement of Chemical Reactions, Chem. Eng. Technol., vol. 38 (7), pp. 1113-1121, 2014. DOI: 10.1002/ceat.201400522
[2] Hoehr, Reichmann et al., Ultrasonic fabrication of polymer plate reactors with a surface coating, in process.


January 2018 - Exkursion zu Sartorius AG und Boehringer Ingelheim

Am 9. und 10. Januar 2018 macht die Arbeitsgruppe Apparatedesign unterstützt durch den Lehrstuhl FSV eine Exkursion zu Sartorius in Göttingen und Boehringer in Ingelheim. Studierende aus den Vorlesungen Pharmaverfahrenstechnik, Good Manufacturing Practice und Mikroverfahrenstechnik bekamen einen sehr guten Einblick in moderne Produktionsmethoden und Tätigkeitsfelder von Bio- und Chemieingenieuren. Ca. 20 Studierende besichtigten Reinräume und chemische Produktionsstätten und waren von der Vielfalt der Eindrücke begeistert.

Contact: Norbert Kockmann


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Photo of Prof. Dr.-Ing. Norbert Kockmann

Prof. Dr.-Ing. Norbert Kockmann

Telephone: 0231 755-8077
Fax: 0231 755-8084


Technische Universität Dortmund
Fakultät Bio- und Chemieingenieurwesen
Arbeitsgruppe ApparateDesign
Geschossbau 3

Room 511