Hydrodynamic characteristics study

The main aim of the present chapter is to verify the capacity of conventional theory to predict the hydrodynamic characteristics of laminar Newtonian incompressible flows in micro-channels in the hydraulic diameter range from dh = 15 to db = 4,010 pm, Reynolds number from Re = 10 up to Re = Recr, and Knudsen number from Kn = 0.001 to Kn = 0.4. The following conclusions can be drawn from this study ... 

Many industrial processes which employ bubble column reactors (BCRs) operate on a continuous liquid flow basis. As a result these BCR s are a substantially more complicated than stationary flow systems. The design and operation of these systems is largely proprietary and there is, indeed a strong reliance upon scale up strategies [1]. With the implementation of Computational Fluid Dynamics (CFD), the associated complex flow phenomena may be anal)rzed to obtain a more comprehensive basis for reactor analysis and optimization. This study has examined the hydrodynamic characteristics of an annular 2-phase (liquid-gas) bubble column reactor operating co-and coimter-current (with respect to the gas flow) continuous modes. 

In the last decade there were many papers published on the study of enzyme catalyzed reactions performed in so-called chromatographic reactors. The attractive feature of such systems is that during the course of the reaction the compounds are already separated, which can drive the reaction beyond the thermodynamic equilibrium as well as remove putative inhibitors. In this chapter, an overview of such chromatographic bioreactor systems is given. Besides, some immobilization techniques to improve enzyme activity are discussed together with modern chromatographic supports with improved hydrodynamic characteristics to be used in this context. 

C. Bentifraouine, C. Xuereb, J.R Riba, An experimental study of the hydrodynamic characteristics of external-loop airlift contactors, J. Chem. Technol. Biotechnol. 69 (1997) 345-349. 

Benincasa et al. (2003) also studied the effect of ionic strength and electrolyte composition on hydrodynamic characteristics of HS. The author s reported that components of different HS fractions behave like organic acids, but that the retention level of fractions with larger components may not be accurately modulated by varying mobile phase properties as these species are either totally retained in acidic phases or released before the void peak at pH 4.2. Authors concluded that pronounced differences exist in the physicochemical properties of some HS components even when particle sizes were similar. 

E. K.T. Kam, E. Alper, S. Al-Safadi, F. Abu-Seedo, M. Absi-Halabi and M. Sabri, Cold flow studies on catalyst properties and hydrodynamic characteristics in ebullated-bed model reactor. Technical Report KISR 4169, Kuwait Institute for Scientific Research, Kuwait, 1992. 

As illustrated by the results presented in Figure 2 and in Table 2 at high ionic strength and high Ca2 + for favorable particle-particle interactions (e.g., in the deposition of non-Brownian particles, F = F%Taviiy + Fdrag +FlVDW Fchem = 0), transport models based on physical and hydrodynamic characteristics of a system can predict the initial kinetics of aggregation and deposition processes in aquatic systems quantitatively. In the presence of repulsive chemical interactions, however, quantitative theoretical predictions of such kinetics are very inaccurate and even many qualitative predictions are not observed. The determination of Fchem in aquatic systems merits study and development,- it is necessary for the quantitative prediction of the kinetics of colloid chemical processes in these systems. 

In the book [117], some data are given on the hydrodynamic characteristics of bodies of various shapes these data mainly pertain to the region of precrisis self-similarity. The influence of roughness of the cylinder surface and the turbulence level of the incoming flow on the drag coefficient is discussed in [522]. In [211], the relationship between hydrodynamic flow characteristics in turbulent boundary layers and the longitudinal pressure gradient is studied. Analysis of the transition to turbulence in the wake of circular cylinders is presented in [333]. 

Rutherford et al. [10], by using LDV, studied the hydrodynamic characteristics of the agitated systems in the Rushton double turbine, where the height of the electrolyte, H, is equal to the tank diameter, D. They detected four unstable and three stable flux patterns. The stable flux patterns were named as parallel, mixed, and divergent (Figure 17.2). 

The mass transfer resistances strongly depend on the nature of the hydrodynamics in the contacting device and the mode of operation. Many devices have been used to study two-phase mass transfer at or near the liquid-liquid interface. Hence, the hydrodynamic characteristics of ion transport through a membrane were presented to evaluate the feasibility that this permeation system can be calibrated as a standardized liquid-liquid system for studying the membrane-moderated PT-catalyzed reaction. The individual mass transfer coefficients and diffusivities for the aqueous phase, organic phase, and membrane phase were determined and then correlated in terms of the conventional Sh-Re-Sc relationship. The transfer time of quaternary salt across the membrane and the thickness of the hydrodynamic diffusion boundary layer are calculated and then the effect of environmental flow conditions on the rate of membrane permeation can be accurately interpreted [127]. 

Experimental data on hydrodynamic properties of natural and biosynthetic lignins in dilute solutions are reviewed. The results of viscometric, translational diffusion, and sedimentation studies provide evidence for the macromolecnles of lignin having a complex topological structure. The benefits and limitations of the theoretical approaches used to describe the topology of lignin macromolecular chains are discussed. The relationship between hydrodynamic characteristic and fractal properties of lignin is considered. 

In the following studies, the hydrodynamics and mass transfer during liquid-liquid flow with ionic liquids in channels with a range of diameters are presented. How patterns, as well as several hydrodynamic characteristics, such as plug length, plug velocity, film thickness, and pressure drop have been investigated. 

To study the effects of residence time on dioxouranium(VI) extraction, experiments were conducted for different channel lengths, ranging from 10 to 31.5 cm at the same total volumetric flow rate, Qn,i = 14.6 cm h, and ionic liquid to aqueous phase flow rate ratio of 1 for initial nitric acid concentration varying from 0.01 to 3 M. Changes in the mixture velocity would alter the hydrodynamic characteristics of the two phase flow, such as plug length and circulation patterns (as shown in Chap. 5), which also affect mass transfer. 

Study of hydrodynamic characteristics scrubber showed that the coefficient of hydraulic resistance depends strongly on the angle of the blade swirler a. It also depends on the movement of gas-dispersed medium defined by the Reynolds number Re =pDv//u. As seen in Fig. 4, with increasing Reynolds number of 8 x lO" sets scaling of The exception is with the swirl angle of blades 35.5°, installation of which continues to increase hydraulic resistance. 

The program ANSYS-14/CFX mathematical model of motion of polydispersed gas system. The character of the movement of dust particles under the influence of centrifugal force. This allowed choosing the desired hydrodynamic conditions and taking into account of the design under various conditions of scrubber. Experimental study of the hydrodynamic characteristics of the device to determine the empirical constants and test the adequacy of the hydrodynamic model. 

Mathematical modeling and determination of the characteristic parameters to predict the performance of membrane solvent extraction processes has been studied widely in the literature. The analysis of mass transfer in hollow fiber modules has been carried out using two different approaches. The first approach to the modeling of solvent extraction in hollow fiber modules consists of considering the velocity and concentration profiles developed along the hollow fibers by means of the mass conservation equation and the associated boundary conditions for the solute in the inner fluid. The second approach consists of considering that the mass flux of a solute can be related to a mass transfer coefficient that gathers both mass transport properties and hydrodynamic conditions of the systan (fluid flow and hydrodynamic characteristics of the manbrane module). 

Tan L, Roghair I, Van Sint Atinaland M Simulation study on the effect of gas permeation on the hydrodynamic characteristics of membrane-assisted micro fluidized beds, Appl Math Model, 2014. http //dx.doi.Org/10.1016/j.apm.2014.04.044 (in press). 

Deepwater sea cage engineering has developed rapidly, but research into hydrodynamic characteristics is relatively weak. Model experiments are very useful methods for such studies, but the main difficulty is in obtaining reasonable simulation criteria for model tests of fishing nets. For such modef tests, the geometric scale A is usually... 

Hydrodynamic properties. The basic hydrodynamic characteristics of a macromolecule are its translational and rotational friction, experimentally studied by methods of diffusion, sedimentation, and viscometry. The chain necklace model [11], which has been very satisfactorily confirmed by the experimental data, is widely used in the hydrodynamics of rigid-chain molecules. 

The theoretical concq>ts of the hydrodynamic behavior of macromolecules reported above are used in practice in the analysis of the propmies of mesogenic macromolecules. This analysis includes preliminary fractionation of the polymer studied, determination of the molecular weights and hydrodynamic characteristics (Py [i]], o) in.a wide range of M, and obtaining the empirical equations which correlate die molecular weight M with the intrinsic viscosity and coefficients D and Sq (Sq is the sedimentation coefficient). 

Quantitative studies of the hydrodynamic characteristics were conducted in [100-103] for the polymers and copolymers listed in Table 3.10, and only copolymers of 3 are soluble in tetrachloroethane [100], while alkylene aromatic polyethers are soluble in dichloroacetic and trifluoroacetic acids [101-103]. The use of acids with a high viscosity and density as solvents limits the possibilities of the sedimentation method. For this reason, for polydecamethylene-tere-phthaloyl di-p-hydroxybenzoate (P-IO-MTOC, polymer 1) and the totally aromatic polyether (PE) containing aromatic rings in the meta and para positions (polymer 2), the molecular weights of the fractions and samples were either determined with the Svedberg equation using sedimentation-diffusion data... 

Ruiz et al. (2005) studied the hydrodynamic characteristics of ebullated-bed systems operated at high pressure and temperature. The purpose of the work was to examine the effect of both variables on the hydrodynamic properties of ebullated-bed systems. The bed porosity and liquid minimum fluidization were measured and... 

Note that filter aid selection must be based on planned laboratory tests. Guidelines for selection may only be applied in the broadest sense, since there is almost an infinite number of combinations of filter media, filter aids, and suspensions that will produce varying degrees of separation. The hydrodynamics of any filtration process are highly complex filtration is essentially a multiphase system in which interaction takes place between solids from the suspension, filter aid, and filter medium, and a liquid phase. Experiments are mandatory in most operations not only in proper filter aid selection but in defining the method of application. Some general guidelines can be applied to such studies the filter aid must have the minimum hydraulic resistance and provide the desired rate of separation an insufficient amount of filter aid leads to a reduction in filtrate quality — excess amounts result in losses is filtration rate and it is necessary to account for the method of application and characteristics of filter aids. 

Heat transfer in micro-channels occurs under superposition of hydrodynamic and thermal effects, determining the main characteristics of this process. Experimental study of the heat transfer in micro-channels is problematic because of their small size, which makes a direct diagnostics of temperature field in the fluid and the wall difficult. Certain information on mechanisms of this phenomenon can be obtained by analysis of the experimental data, in particular, by comparison of measurements with predictions that are based on several models of heat transfer in circular, rectangular and trapezoidal micro-channels. This approach makes it possible to estimate the applicability of the conventional theory, and the correctness of several hypotheses related to the mechanism of heat transfer. It is possible to reveal the effects of the Reynolds number, axial conduction, energy dissipation, heat losses to the environment, etc., on the heat transfer. 

The quasi-one-dimensional model of laminar flow in a heated capillary is presented. In the frame of this model the effect of channel size, initial temperature of the working fluid, wall heat flux and gravity on two-phase capillary flow is studied. It is shown that hydrodynamical and thermal characteristics of laminar flow in a heated capillary are determined by the physical properties of the liquid and its vapor, as well as the heat flux on the wall. 

In this work, an experimental study was conducted on gelatin in semi-dilute region in water solution and research the effect of temperature, pH, zeta potential, and ionic strength on hydrodynamic properties by viscometiy, in order to determine the conformational characteristic, and phase transition (Tgei). 

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