13 Zentrale Universitätseinrichtungen
Permanent URI for this collectionhttps://elib.uni-stuttgart.de/handle/11682/14
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Item Open Access Kontrollverfahren zur Kristallisation von Ascorbinsäure(1989) Rochlenko, A. A.; Macievskij, G. A.; Truksina, T. S.; Zaruckij, V. V.; Pertschi, Ottmar (Übersetzer)Crystallization of ascorbic acid from its aquivalent saturated solutions with cooling from 60 to 4° was controlled by measuring the concentration of the crystals in the solution. The process was simplified by measuring the concentration of the crystals in the solution by passing 2 - 3 MHz ultrasonic vibrations through the constantly stirred solution, and the concentration of crystals was determined from the absorption coefficient of ultrasonic vibrations.Item Open Access Materialien für experimentelle Untersuchungen zur hygienischen Bewertung der Wasserentsalzung durch umgekehrte Osmose(1979) Rachmanin, Ju. A.; Davydova, S. G.; Selivanov, S. B.; Martynova, I. M.; Mel'nikova, A. I.; Pertschi, Ottmar (Übersetzer)hygienische Bewertung der Wasserentsalzung durch umgekehrte OsmoseItem Open Access Particle-resolved simulation of the pyrolysis process of a single plastic particle(2024) Zhang, Feichi; Tavakkol, Salar; Galeazzo, Flavio C. C.; Stapf, DieterParticle-resolved simulations have been performed to study the pyrolysis process of a high-density polyethylene (HDPE) particle in an inert hot nitrogen flow. The simulations resolve the velocity and temperature boundary layers around the particle, as well as the gradients of temperature and concentration within the particle. The objective of this work is to gain an in-depth understanding of the effect of particle morphology-specifically, the particle size and shape-on the interplay between heat transfer and pyrolysis progress, as well as to assess the applicable particle size when using the Lagrangian concept for simulating plastic pyrolysis. In all simulation cases, the pyrolysis reaction is initiated at the external surface of the particle, where the particle is heated the fastest. The reaction front propagates inward toward the core of the particle until it is fully pyrolyzed. For particle diameters larger than 4 mm, distinct temperature gradients within the particle can be detected, leading to a temperature difference of more than 10 K between the core and the external surface of the plastic particle. In this case, the Lagrangian simulations yield a considerably slower conversion compared with the particle-resolved simulations. Moreover, the cylindrical particle in longitudinal flow has been found to be pyrolyzed more slowly compared with the spherical and shell-shaped particles, which is attributed to the enhanced heat transfer conditions for the cylindrical particle. The results reveal the importance of considering particle morphology when modeling plastic pyrolysis. In addition, the Lagrangian approach, which assumes particle homogeneity, is only applicable for particle diameters smaller than 2 mm when modeling plastic pyrolysis.