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In this study, the flow fields of two‐stage impellers, consisting of combinations of different impeller types on one shaft, are investigated using stereo particle image velocimetry. Based on the results of torque measurements, diameters for different impellers are determined in order to achieve matching power input of the individual turbines. When implemented adequately, both selected impellers are able to contribute their respective characteristics, resulting in flow fields that differ significantly from those induced by single‐stage impellers as well as two‐stage setups consisting of identical impellers. [ABSTRACT FROM AUTHOR]

The achievable grinding fineness of spiral jet mills does not only depend on the comminution efficiency in the region of the nozzle jets but is also significantly affected by the separation efficiency in the region of the product outlet. Therefore, the aim of this study is to investigate the influences of the product outlet diameter and different particle trap rings on the flow conditions and the grinding performance, optimizing the classifying efficiency of spiral jet mills. The velocity fields analyzed by particle image velocimetry and the experimental grinding results show that the classification process can be optimized by both reducing the product outlet diameter and installing a particle trap ring. [ABSTRACT FROM AUTHOR]

In this study, flow fields in stirred tank reactors are investigated by a fluorescence tracer method. For these measurements, a fluorescent dye is inserted into a stirred tank reactor and distributed by the impeller flow, following the characteristic main circulation pathways. By this means, the main flow fields can be detected and visualized. Originally developed and used for the investigation of viscoelastic fluids, the method was adapted for Newtonian fluids with low viscosity in this study, with impeller installation height and impeller Reynolds numbers selected as influencing parameters. The resulting flow fields in both single‐ and double‐impeller setups match the known structures from literature excellently. Therefore, the developed fluorescence tracer method has proven to be a promising supplement to the established repertoire of fluid investigation methods, with little effort in both experiment itself as well as the following data analysis steps. [ABSTRACT FROM AUTHOR]

Reusing wastewater from oil‐related industries is becoming increasingly important, especially in water‐stressed oil‐producing countries. Before oily wastewater can be discharged or reused, it must be properly treated, e.g., by membrane‐based processes like ultrafiltration. A major issue of the applied membranes is their high fouling propensity. This paper reports on mitigating fouling inside ready‐to‐use ultrafiltration hollow‐fiber modules used in a polishing step in oil/water separation. For this purpose, in‐situ polyzwitterionic hydrogel coating was applied. The membrane performance was tested with oil nano‐emulsions using a mini‐plant system. The main factors influencing fouling were systematically investigated using statistical design of experiments. [ABSTRACT FROM AUTHOR]

Surface patterning is a recent promising approach to promote performance of pressure‐driven membranes in water treatment and desalination. Nevertheless, knowledge about foulant deposition mechanisms, especially at early stage of filtration, is still lacking. The applicability of particle imaging velocimetry to study fluid characteristics atop surface patterned thin‐film composite membranes was investigated at different operating conditions. This work is an important first step toward reliable understanding of the impacts of topographical membrane surface modification on hydrodynamic conditions and foulant deposition mechanisms. [ABSTRACT FROM AUTHOR]

Suspending particles in liquids is an important and versatile case for industrial stirring processes. By using advanced optical, non‐invasive measurement techniques like particle image velocimetry (PIV), it is possible to gain deep insights into the involved fluid dynamics without affecting the flow. However, for suspensions, the application of PIV is not trivial since both, suspended and tracer particles are present and need to be discerned during experiments. The here presented method development solves this problem and thus leads to a better insight into turbulent kinetic energy distribution, which can be utilized for process optimization through improved stirred vessel design. [ABSTRACT FROM AUTHOR]

By integrating a water‐soluble polymer, which has the ability to complex heavy metal ions into ultrafiltration membranes, the separation process could be enhanced to enable also filtration of these species. In this work, a membrane and an adsorber polymer were functionalized with complementary reactive groups so that the adsorber polymer could be immobilized in the porous support layer of the ultrafiltration membrane via click reaction. The separation performances and membrane characteristics of the synthesized membranes are comparable to those of conventional UF membranes. [ABSTRACT FROM AUTHOR]

Novel ultrafiltration membranes are prepared from solution of cellulose in ionic liquids by phase inversion on filter paper as support. Membrane performance can be adjusted by varying the casting solution composition. The addition of dimethyl sulfoxide leads to a change in solvent quality of the used ionic liquid, which has a direct influence on the membrane structure formation. However, it does not have a big influence on the membrane performance but can benefit the processing of cellulose to membranes via reducing the viscosity of the solution and costs by decreasing the amount of ionic liquid. [ABSTRACT FROM AUTHOR]

Interest in thin‐film membranes with properties specially tailored to the respective separation process is growing. In order to obtain such membranes with high permselectivity and fouling resistance, established membrane systems are combined with new building blocks. Star polymers are a class of promising building blocks. In this study, star polymers with anion exchange groups of variable molecular weight and low polydispersity were synthesized by atom transfer radical polymerization. The anion exchange groups were tertiary amino and quaternary ammonium groups. The resulting star polymers were integrated into polyamide thin‐film composite membranes using interfacial polymerization. [ABSTRACT FROM AUTHOR]

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The results of measurements using two different particle image velocimetry (PIV) systems (2D-PIV versus stereo-PIV) are compared and the obtained data with a coupled CFD simulation are also correlated. A stirred vessel with internal helical coil as additional heat exchanger is analyzed with these settings. Results for the velocity fields and turbulent kinetic energy distribution are shown and the feasibility of stereo-PIV measurements by using refractive index matching fluid is proven. This investigation provides a good accordance and consistency between the different PIV systems and the related CFD. [ABSTRACT FROM AUTHOR]