Abstract:This study presents some results from the numerical simulation of the flow in an industrial solid bowl centrifuge used for particle separation in industrial fluid processing. The computational fluid dynamics (CFD) software Fluent was used to simulate this multiphase flow. Simplified two-dimensional and three-dimensional geometries were built and meshed from the real centrifuge geometry. The CFD results show a boundary layer of axially fast moving fluid at the gas-liquid interface. Below this layer there is a t… Show more
“…Starting from a laboratory scale (sizing factor 1), a pilot scale (sizing factor in the decadic range) is used to validate the scale‐up assumptions for a real‐size apparatus (sizing factor in the range of hundreds or more). For a different field of application, a similar approach has already been reported in 20. However, the presented method can equally be applied with a calculatory scale‐up from laboratory scale to real scale without the intermediate pilot‐scale step.…”
Section: Scale‐up Methods Based On Mathematical Modelmentioning
A thermally regenerative ammonia battery (TRAB) is a new approach for converting low-grade thermal energy into electricity by using an ammonia electrolyte and copper electrodes. TRAB operation at 72 °C produced a power density of 236 ± 8 Wm(-2), with a linear decrease in power to 95 ± 5 Wm(-2) at 23 °C. The improved power at higher temperatures was due to reduced electrode overpotentials and more favorable thermodynamics for the anode reaction (copper oxidation). The energy density varied with temperature and discharge rates, with a maximum of 650 Wh m(-3) at a discharge energy efficiency of 54% and a temperature of 37 °C. The energy efficiency calculated with chemical process simulation software indicated a Carnot-based efficiency of up to 13% and an overall thermal energy recovery of 0.5%. It should be possible to substantially improve these energy recoveries through optimization of electrolyte concentrations and by using improved ion-selective membranes and energy recovery systems such as heat exchangers.
“…Starting from a laboratory scale (sizing factor 1), a pilot scale (sizing factor in the decadic range) is used to validate the scale‐up assumptions for a real‐size apparatus (sizing factor in the range of hundreds or more). For a different field of application, a similar approach has already been reported in 20. However, the presented method can equally be applied with a calculatory scale‐up from laboratory scale to real scale without the intermediate pilot‐scale step.…”
Section: Scale‐up Methods Based On Mathematical Modelmentioning
A thermally regenerative ammonia battery (TRAB) is a new approach for converting low-grade thermal energy into electricity by using an ammonia electrolyte and copper electrodes. TRAB operation at 72 °C produced a power density of 236 ± 8 Wm(-2), with a linear decrease in power to 95 ± 5 Wm(-2) at 23 °C. The improved power at higher temperatures was due to reduced electrode overpotentials and more favorable thermodynamics for the anode reaction (copper oxidation). The energy density varied with temperature and discharge rates, with a maximum of 650 Wh m(-3) at a discharge energy efficiency of 54% and a temperature of 37 °C. The energy efficiency calculated with chemical process simulation software indicated a Carnot-based efficiency of up to 13% and an overall thermal energy recovery of 0.5%. It should be possible to substantially improve these energy recoveries through optimization of electrolyte concentrations and by using improved ion-selective membranes and energy recovery systems such as heat exchangers.
“…To our knowledge, the commercial CFD code FLUENT offers no alternative approaches, e.g., multiple time steps of the scalar equation per single time step of the flow field equations or the application of a time-averaged (or periodically recurring) flow field. A validation by means of grade efficiency curves is not very promising because particle tracking methods in FLUENT for sedimentation of submicron particles have already shown large deviations from analytical and experimental results [21,22]. Fig.…”
“…Durch die wachsende Rechenleistung halten CFD‐Simulationen Einzug in einige Bereiche der Verfahrenstechnik. In der Literatur sind inzwischen sowohl eigenentwickelte als auch Standardmethoden zur numerischen Beschreibung von Mehrphasenströmungen und zur Strömungsuntersuchung in Zentrifugen bekannt . Um auch in der mechanischen Flüssigkeitsabtrennung für semi‐batch oder kontinuierlich betriebene Vollmantelzentrifugen aufgelöste Simulationen als Unterstützung zu experimentellen Untersuchungen nutzen zu können, befasst sich das IMVM seit einiger Zeit mit der räumlichen und zeitlichen Auflösung des Strömungsfelds.…”
Section: Charakterisierung Des Prozessverhaltens Von Vollmantelzentriunclassified
Im Zuge der Initiative Industrie 4.0 erhöht sich der Digitalisierungsgrad auch in der Prozessindustrie. Eine enge Verknüpfung von Analyseverfahren und dynamischer Prozessmodelle erlaubt die Optimierung der Prozesskontrolle und Steuerung auch in der industriellen Trenntechnik. Zu diesem Zweck müssen mathematische Modelle zur Beschreibung der Prozessebene in Echtzeit bekannt sein. Im Bereich der Fest/Flüssig‐Trennung erzwingt die voranschreitende Digitalisierung die Entwicklung von numerischen Methoden und von Short‐cut‐Modellen zur Vertiefung des Prozessverständnisses und der besseren Auslegung der Anlagen. Aufgelöste Strömungssimulationen dienen hier als Unterstützung zu Experimenten und zur Ableitung geeigneter Short‐cut‐Modelle. Am Beispiel von Vollmantelzentrifugen wird die Entwicklung dynamischer Prozessmodelle und deren Anwendung beschrieben.
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