On the Volume Fraction Effects of Inertial Colliding Particles in Homogeneous Isotropic Turbulence 1

The main objective of the present study is the investigation of volume fraction effects on the collision statistics of nonsettling inertial particles in a granular medium as well as suspended in an unsteady homogeneous isotropic turbulent flow. For this purpose, different studies with mono-disperse Lagrangian point-particles having different Stokes numbers are considered in which the volume fraction of the dispersed phase is varied between 0.001 and 0.01. The fluid behavior is computed using a three-dimensional Lattice-Boltzmann method. The carrier-fluid turbulence is maintained at Taylor microscale Reynolds number 65.26 by applying a spectral forcing scheme. The Lagrangian particle tracking is based on considering the drag force only and a deterministic model is applied for collision detection. The influence of the particle phase on the fluid flow is neglected at this stage. The particle size is maintained at a constant value for all Stokes numbers so that the ratio of particle diameter to Kolmogorov length scale is fixed at 0.58. The variation of the particle Stokes number was realized by modifying the solids density. The observed particle Reynolds and Stokes numbers are in between [1.07, 2.61] and [0.34, 9.79], respectively. In the present simulations, the fluid flow and the particle motion including particle-particle collisions are based on different temporal discretization. Hence, an adaptive time stepping scheme is introduced. The particle motion as well as the occurrence of inter-particle collisions is characterized among others by Lagrangian correlation functions, the velocity angles between colliding particles and the collision frequencies. Initially, a fluid-free particle system is simulated and compared with the principles of the kinetic theory to validate the implemented deterministic collision model. Moreover, a selection of results obtained for homogeneous isotropic turbulence is compared with in literature available DNS and LES results as well. According to the performed simulations, the collision rate of particles with large Stokes numbers strongly depends on the adopted volume fraction, whereas for particles with small Stokes numbers the influence of particle volume fraction is less pronounced

Experimental analysis of a paraffin-based cold storage tank

[EN] The aim of this study is to characterize a paraffin-based cold storage tank. Novel experimental results are presented for this system which combines a significant amount of paraffin (1450 kg) immersed around 18 spiral-shaped coils disposed in counter-current flow. The paraffin has a phase-change temperature in the range 4 8 °C as measured by a 3-layer calorimeter. Different tests have been carried out with a constant mass flow rate and supply temperature. Around 31% of the paraffin has hardly any contact with the coils and hereby acts as a dead mass. The results show the importance of natural convection within the phase-change-material, particularly during the melting process. The highest efficiency has been achieved for the lowest supply temperatures and mass flow rates of the heat transfer fluid.The authors gratefully acknowledge the fundings from ACCIONA Infraestructuras.Torregrosa-Jaime, B.; López-Navarro, A.; Corberán, JM.; Esteban-Matías, JC.; Klinkner, L.; Payá-Herrero, J. (2013). Experimental analysis of a paraffin-based cold storage tank. International Journal of Refrigeration. 36(6):1632-1640. doi:10.1016/j.ijrefrig.2013.05.001S1632164036

Tagungsband Symposium Maschinenbau

Das Programm des Maschinenbau-Symposiums zeigt zum einen die Bedeutung der Maschinenbaubranche in Deutschland und zum anderen berichten erfolgreiche Absolventen aus ihren Unternehmen

Sekundaere Keimbildung Schlussbericht

TIB: RN 1908 (1979-5) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Einfluss des Druckes auf den Foerdervorgang wandgleitender dispers-plastischer Materialien in Schneckenmaschinen Abschlussbericht

Technische Informationsbibliothek Hannover: AC--6049. / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Abschlussbericht zum Projekt BioMeth - Biologische Methanisierung mit Membranbegasung in einer Molke-Pilotbiogasanlage

In dem Projekt BioMeth wurde der Ansatz der Membranbegasung zur Erhöhung der Verfügbarkeit von gelöstem Wasserstoff für die biologische Methanisierung im Sinn der Etablierung eines Power-to-Gas-Konzeptes zur Energiespeicherung verfolgt. Übergeordnetes Ziel war die Entwicklung eines skalierbaren Verfahrenskonzeptes, dass sich zur Nutzung CO2-haltiger Gasvolumenström eignet. Geplant war es, das Verfahren am Beispiel der Biogasanlage der Biokäserei Monte-Ziego in Teningen zu demonstrieren und dort das bestehende Konzept der parallelen Abwasseraufbereitung und Energieerzeugung zu erweitern. Die ursprüngliche Struktur des Arbeitspaketplanes ist in nachfolgender Abbildung gezeigt

Trennsysteme mit nichtporoesen Membranen. Der Einsatz der Pervaporation und Dampfpermeation fuer die Stofftrennung bei chemischen Prozessen und im Umweltschutz Abschlussbericht

Pervaporation and vapour permeation process have been analyzed and compared with conventional methods of thermal material separation processes with regard to (i) improvement of conventional esterification processes (acetic acid-ethanol; acetic acid-isopropanol), (ii) aceotropic separation of organic systems (benzene-cyclohexane; methanol-dimethylcarbonate) and (iii) separation and recovery of organic substances from waste water (aniline-water). Large-scale application is partially limited by overall process economics. To the technically and economically advantageous membrane processes belong the vapour permeation for selective water removal from esterification systems and the combination of rectification and pervaporation for methanol-dimethylcarbonate separation. The efficiency of different membrane types in these processes are compared. (WEN)Available from TIB Hannover: F95B672+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Forschung und Technologie (BMFT), Bonn (Germany)DEGerman

Druckverlust und Waermeuebergang an querangestroemten Rohrbuendel-Waermeaustauschern in Blasensaeulen-Reaktoren

TIB: RN 1908 (1984-5) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman