Droplet entrainment was investigated in the feed section of distillation columns for multiple feed inlet devices under different flow conditions. Entrainments from two-phase flow regimes were measured in the feed section of a column with an air and water system. A new feed inlet device named demister flash box was developed. Measurements with two-phase flow regime in the feed pipe indicated that the demister flash box had the lowest entrainment. Experiments with a surfactant in water due to low surface tension demonstrated that the entrainment was higher compared to water. In addition, entrainment determinations with high droplet flow rate from a spray nozzle in feed were conducted. The results indicated that the V baffle had the lowest entrainment.

To optimize the performance of oil‐free reciprocating piston compressors, the leakage flow through the piston seal has to be minimized. Therefore, the effects of the geometrical parameters and shapes of labyrinth seals on the leakage flow are examined. The main geometrical parameters and shapes are investigated by means of computational flow dynamics simulations. The optimum geometries obtained from the simulations are experimentally tested on a compressor rig. The rectangle labyrinth shows the lowest leakage followed by a novel semicircle geometry and the triangle geometry shows the highest leakage flow among the labyrinths. The straight seal exhibits the highest leakage flow rate. It can be concluded that the rectangle labyrinth reduces the leakage flow rate in the most efficient way.

This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. Im Rahmen diesesBeitrags werden experimentelle Untersuchungen zur Tropfenabscheidung im Einleitbereich eines Stoffaustauschapparates für zweiphasige Strömungen vorgestellt. Dafür wurde in einem Versuchsstand im Pilotmaßstab der qualitative Tropfenmitriss für unterschiedliche Tropfenabscheider eines Stoffaustauschapparates vermessen. Die daraus resultierenden Ergebnisse werden in diesem Beitrag hinsichtlich ihrer Aussagekraft zur Vermeidung von Tropfenmitriss diskutiert und bewertet. Darüber hinaus wird ein kurzer Ausblick über simulative Arbeiten zur Bestimmung des Tropfenmitriss gegeben.

Micellar casein fibers of defined size and internal structure can be produced by the extrusion of cold-renneted casein micelles into a warm, calcium-rich coagulation bath. Calcium phosphate contacts within the casein matrix are important for fiber stability and production but become less important under acidic pH conditions. We demonstrate this with swelling experiments in media with pH < 2, which we adjust with citric acid of different molarities. In contrast to the simple swelling of dried casein fibers in water, a two-phase process takes place in citric acid similar to swelling in 1 N HCl. However, instead of a second deswelling step, we observe in citric acid that the fiber swells further. The observation is explained by a pH-dependent transition from a rennet casein gel to an acidified rennet gel. This can be simulated with a kinetic model that couples two second-order rate equations via a time-varying ratio. The final swelling values decrease with increasing proton concentration via a scaling relation, which is also confirmed by swelling in other acids (HCl or acetic acid) in this pH range. We attribute this to a decrease in the molecular weights of the aggregated casein structures within the strands of the gel network.

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