Fluid-dynamic properties

In 1976 he was appointed to Associate Professor for Technical Chemistry at the University Hannover. His research group experimentally investigated the interrelation of adsorption, transfer processes and chemical reaction in bubble columns by means of various model reactions a) the formation of tertiary-butanol from isobutene in the presence of sulphuric acid as a catalyst b) the absorption and interphase mass transfer of CO2 in the presence and absence of the enzyme carboanhydrase c) chlorination of toluene d) Fischer-Tropsch synthesis. Based on these data, the processes were mathematically modelled Fluid dynamic properties in Fischer-Tropsch Slurry Reactors were evaluated and mass transfer limitation of the process was proved. In addition, the solubiHties of oxygen and CO2 in various aqueous solutions and those of chlorine in benzene and toluene were determined. Within the framework of development of a process for reconditioning of nuclear fuel wastes the kinetics of the denitration of efQuents with formic acid was investigated. 

The fluid dynamic properties of continuous magnetic media, including liquid ferromagnetic media (ferrofluids), are described by the Navier-Stokes equations with the addition of terms describing the interaction with the magnetic field and are the subject of a considerable number of studies (for a review, see Ref. 1). The motion of discrete magnetic particles in a very... 

Currently available data for the flow properties of the fluidized catalyst bed are fragmentary, since the local motion of the emulsion phase is diflicult to measure experimentally. Therefore, it is useful to clarify the flow properties of the bed in terms of our knowledge of bubble columns. First, the fluid-dynamic properties of the bubble columns will be explained then, the available data will be adapted to apply to fluid catalyst beds. The reader will be able to picture an emulsion phase of carefully prepared catalyst particles operating in intense turbulence for fluidized beds under conditions of practical interest. This turbulence distinguishes the flow properties of fluid catalyst beds from those of widely studied teeter beds. 

Longitudinal dispersion in the continuous phase (the liquid phase for a bubble column, and the emulsion phase for a fluidized catalyst bed) is closely related to flow properties of the equipment. Here, we wish to describe the longitudinal dispersion phenomena in terms of the fluid-dynamic properties of the equipment. The prime purpose is to test whether the fluid-dynamic analysis developed earlier is sound, but lon-... 

Practical application of advanced process control for chromatographic processes is still at the beginning. Optimal operation of large-scale production should also include the adaptation and optimization of thermo- and fluid-dynamic properties, which might vary during extended operation. Progress in this field is very closely linked to improved detectors and other measurement and control devices. 

The lava-lamp model for the Earth s mantle (Albarede 8k van der Hilst, 1999 Kellogg et al., 1999) takes its name from that household curiosity of the 1960s based upon the fluid-dynamic properties of liquids with near identical densities. The model is based upon seismic observations of an irregular, deep boundary layer in the mantle at 1,600-2,000 km depth. 

The role of mixing has been studied in systems with more complex reaction schemes or considering more complex fluid-dynamical properties, and in the context of chemical engineering or microfluidic applications (for reviews on microfluidics see e.g. Squires (2005) or Ottino and Wiggins (2004)). Muzzio and Liu (1996) studied bi-molecular and so-called competitive-consecutive reactions with multiple timescales in chaotic flows. Reduced models that predict the global behavior of the competitive-consecutive reaction scheme were introduced by Cox (2004) and by Vikhansky and Cox (2006), and a method for statistical description of reactive flows based on a con-... 

Fluid Dynamics Knowledge of fluid dynamics is important to insure that screening experiments are structured to acquire data on how fluid dynamic properties (such as SCFCO2 solvent diffusivity and superficial velocity) will affect the commercial plant s performance and economic efficiency. For example, in many cases a commercial plant s performance and economic efficiency are sensitive to the superficial velocity of the SCFCO2 solvent. Experiments should be designed to yield data that can be used to determine how sensitive commercial plant performance and economic efficiency is to superficial velocity of the SCFCO2. 

Gas-flowing solids-fixed bed contactors, according to their mass transfer and fluid dynamics properties, are suitable for various environmental appUcations, which involve adsorption of pollutants. Several investigations [6,10,36,37,41] have been carried out at pilot-plant level, and the results were promising for the design of industrial equipment. In the presented works [6,10,36,37,41], the adsorption process is followed by the chemical reaction on the flowing solids phase. 

Most of the research up to date was primarily directed toward the determination and prediction of major fluid dynamic properties, including heat and mass transfer rates. Although there is still lack of data and prediction models for some of the parameters, many favorable features have been identified low pressure drop, high heat and mass transfer rates, and low axial dispersion of gas and flowing solids. 

Gas-liquid phase segregation is typically required following some other separation process, such as distillation, absorption, evaporation, gas-liquid reactions, and condensation. Before separation techniques or equipment can be selected, the parameters of the separation must be defined. Information on volume of gas or liquid, volume ratio of the phases, and disper -phase particle size—that is, drop or bubble size-should be known or estimated. For existing operations, measurements are a possibility, while for new facilities analogies from data on other processes could be used. Laboratory or pilot riant tests may be considered, but it is difficult to maintain all fluid dynamic properties constant while chaining scale and wall effects may be significant on the small scale. 

It is still common practice to estimate the fluid dynamic properties from empirical correlations. Such correlations are usually developed from "cold flow" measurements which are often not properly designed and evaluated. It is understood that use of empirical correlations is of limited value and their predictions may lead to serious errors. This is particularly valid for those quantities which characterize interfacial properties like mass transfer coefficients, interfacial areas and phase holdups. It is now obvious that properties like density, viscosity, and surface tension are not always sufficient to describe fluid dynamic and interfacial phenomena. 

There are many interesting and important reports on the fluid dynamic properties of magnetic fluids. In the following, characteristic behaviors will be introduced. 

Farag et al. [65] adapted a pair of the reflective fibre optic sensors, originally developed by Sobocinski et al. [185], for measuring fluid dynamic properties (e.g., bubble fraction and bubble frequency) in a pilot scale turbulent fluidized bed. Each of the probes consisted of one emitter and two receivers. A pair of reflective fibre optic sensors, 3 mm apart, were used to measure fluid dynamic properties. The bubble fractions, (3, was defined as the cumulative contact times Xm divided by the total sampling time T ... 

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