Fluid dynamics separation

The preceding accomplishments are applied in nature, but required tremendous amounts of basic research on mass transfer, interactions of materials with biological components, fluid dynamics, separation processes (especially chromatography and membrane separations), and biochemical kinetics. 

Fluid coking, 18 650-651 Fluid-column roaster, 26 564—565 Fluid deposits, 17 694-695 Fluid-dynamic separating devices, 22 275, 283. See also Classifiers Fluid energy activated flowmeters, 11 654-669... 

E. RxX z m. Aerodynamic Separation of Gases and Isotopes, Eecture Series 1978, Von Karmen Institute for Fluid Dynamics, Belgium, 1978. 

The highest level of integration would be to establish one large set of equations and to apply one solution process to both thermal and airflow-related variables. Nevertheless, a very sparse matrix must be solved, and one cannot use the reliable and well-proven solvers of the present codes anymore. Therefore, a separate solution process for thermal and airflow parameters respectively remains the most promising approach. This seems to be appropriate also for the coupling of computational fluid dynamics (CFD) with a thermal model. ... 

The present book is devoted to both the experimentally tested micro reactors and micro reaction systems described in current scientific literature as well as the corresponding processes. It will become apparent that many micro reactors at first sight simply consist of a multitude of parallel channels. However, a closer look reveals that the details of fluid dynamics or heat and mass transfer often determine their performance. For this reason, besides the description of the equipment and processes referred to above, this book contains a separate chapter on modeling and simulation of transport phenomena in micro reactors. 

Individual process steps identified in a conceptual design (reactors or separation/purification units) are studied experimentally in the laboratory and/or by computer simulation (see simulation programs as given in SOFTWARE DIRECTORY or Computational Fluid Dynamics (CFD) programs for studying fluid dynamics, such as PHOENIX, FLUENT, and FIDAP). 

There have been several studies in which the flow patterns within the body of the cyclone separator have been modelled using a Computational Fluid Dynamics (CFD) technique. A recent example is that of Slack et a/. 54 in which the computed three-dimensional flow fields have been plotted and compared with the results of experimental studies in which a backscatter laser Doppler anemometry system was used to measure flowfields. Agreement between the computed and experimental results was very good. When using very fine grid meshes, the existence of time-dependent vortices was identified. These had the potentiality of adversely affecting the separation efficiency, as well as leading to increased erosion at the walls. 

The vertical cylindrical column provides, in a compact form and with the minimum of ground requirements, a large number of separate stages of vaporisation and condensation. In this chapter the basic problems of design are considered and it may be seen that not only the physical and chemical properties, but also the fluid dynamics inside the unit, determine the number of stages required and the overall layout of the unit. 

Liibberstedt [64] tested three different hydrocyclones for HeLa cell separation a 7 mm Bradley [67], a 10 mm Mozley (Richard Mozley Ltd., Redruth, UK), and a 10 mm Dorr-Oliver (Dorr-Oliver GmbH, Wiesbaden, Germany) (the dimension quoted here is the diameter of the cylindrical part of each hydrocyclone). The best results were obtained with the Dorr-Oliver hydrocyclone (Fig. 3), which produced a cell separation efficiency of 81 % when working at a pressure drop of 300 kPa and a flow rate of 2.8 L min When operating with two 10 mm Dorr-Oliver connected in series (the overflow of the first as feed for the second) at 200 kPa, the global efficiency of the arrangement was 94% [65]. These experimental values confirm the computational fluid dynamics (CFD) predictions that high levels of efficiencies for mammalian cells could be achieved with small diameter hydrocyclones [46]. 

Although much progress has been made in the last decade regarding operation, design and scale-up of spin-filters, in most works found in the literature either fouling or retention problems (or both) were observed. A better comprehension of the fluid and particle dynamics involved in spin-filter perfusion would improve this situation. In this context, a valuable tool that could be used is computational fluid dynamics (CFD), which has been recently employed for the design and performance prediction of other cell separation devices [46,114]. 

Since it will take several years to realize such an integral software toolbox, individual approaches with separate steps have to be applied to meet gradually the requirements of microreactor design. Standard software for computational fluid dynamics is directly applicable in this context, and there are also powerful software tools for the simulation of special steps in microfabrication processes. However, there has been rather little experience with materials for microreactors, optimization of microreactor design, and, in particular, the treatment of interdependent effects. Consequently, a profound knowledge of the basic properties and phenomena of microreaction technology just described is absolutely essential for the successful design of microreaction devices. 

The reactor is the nucleus of the process. Getting the fluid dynamics right in the reactor means improved safety, productivity, and selectivity, which in turn influences upstream (reduced raw material costs) and downstream (reduced separation and waste treatment costs) see Figure 1. 

Every separation unit operation is governed by the continuum conservation laws, and thus, in principle, everything meaningful to know in the continuum for any process can be determined with computational fluid dynamics (CFD) (92). In recent years there have been significant academic and industrial efforts to enable... 

The key reactive separation topics to be addressed in the near future are a proper hydrodynamic modeling for catalytic internals, including residence time distribution account and scale-up methodology. Further studies on the hydrodynamics of catalytic internals are essential for a better understanding of RSP behavior and the availability of optimally designed catalytic column internals for them. In this regard, the methods of computational fluid dynamics appear very helpful. 

Kenig EY, Kloker M, Egorov Y, Menter F, Gorak A. Towards improvement of reactive separation performance using computational fluid dynamics. Proceedings of International Symposium on Multifunctional Reactors (ISMR-2), Nuremberg, 2001. 

Computational fluid dynamics were used to describe the flow which undergoes a fast transition from laminar (at the fluid outlets) to turbulent (in the large mixing chamber) [41]. Using the commercial tool FLUENT, the following different turbulence models were applied a ke model, an RNC-ki model and a Reynolds-stress model. For the last model, each stream is solved by a separate equation for the two first models, two-equation models are applied. To have the simulations at... 

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