Flow-type parameter

Figure 3.17 Birefringence as a function of the eigenvalue of the velocity gradient tensor, G, for planar flows generated in a four-roll mill, for dilute solutions of polystyrenes of three different molecular weights in polychlorinated biphenyl solvent. Here G is the strain rate and a the flow type parameter. For planar extension, a — 1 and G = is the extension rate for simple shear, a = 0 and G = y is the shear rate. The different symbols correspond to a values of 1.0 (0)> 0.8 (A), 0.5 (-1-), and 0.25 (diamonds). The curves are theoretical predictions from the FENE dumbbell model, including conformation-dependent drag (discussed in Section 3.6.2.2.2). (From Fuller and Leal 1980, reprinted with permission from Steinkopff Publishers.)...

Column Type Minimum Reduced Plate Height Minimum Reduced Velocity flow Resistance Parameter Separation Impedance... 

Continuous operation In flow-type reactors, e.g., loop reactors, the space velocity of the reaction is determined through the installed static mixing device that is used to generate the dispersion, together with the velocity of the circiflating medium (catalyst- and substrate/product phase). Knowledge of these parameters allows one to set up a kinetic model for the investigated reaction. 

The classification system introduced by Carr [29,30] was used to evaluate the flow properties of the sorbitol powders. In Carr s system, a flowable powder is defined as free flowing and will tend to flow steadily and consistently. This is to be contrasted with a floodable powder, which will exhibit an unstable, discontinuous, and gushing type of flow. The parameters in Carr s system include the angle of repose, angle of spatula, compressibility, cohesion, and dispersibility. Based on these parameters, flowability and floodability indices are calculated to determine the handling properties of bulk solids. 

Concurrent flow of liquid and gas can be simulated by the homogeneous model of Section 6.8.1 and Eqs. 6.109 or 6.112, but several adequate correlations of separated flows in terms of Lockhart-Martinelli parameters of pipeline flow type are available. A number of them is cited by Shah (Gas-Liquid-Solid Reactor Design, McGraw-Hill, New York, 1979, p. 184). The correlation of Sato (1973) is shown on Figure 6.9 and is represented by either... 

Paper refers to the contents of the title paper in Vol. 25, N. 5, of May 1972, and presents an empirical analysis of a number of carefully conducted tests in cooling towers of the vertical, counter-flow type. In order to put cooling tower performance on a common basis the area to height factor is introduced. Parameters examined by Dr. Whillier are reexamined and use is made of the area to height factor to predict cooling tower performance. 

In the batch-type reaction system, however, the pressure cannot be controlled during the treatment. Table 1 shows a maximum pressure for various supercritical alcohols at 300 and 350°C. It can be observed that at the same temperature, they gave different maximum pressure and that the pressure tended to be lower as the alkyl chain of the alcohol became longer. Previously, it was found that the reaction pressure is an important reaction parameter in enhancing the reaction rate (11). Therefore, the flow-type reaction system, which can control the reaction pressure up to 50 MPa, was used to study the effect of the reaction pressure on the formation of alkyl esters. Reaction temperature and reaction time were set at 300°C and 20... 

The heterogeneously catalyzed alkoxylation of alpha-pinene and limonene over beta zeolite provides excellent results in both a discontinuous batch reactor and a continuous flow-type apparatus with a fixed bed reactor. In both reactors, the use of methanol as addition compound and limonene as feedstock gives l-methyl-4-[alpha-methoxy-isopropyl]-l-cyclohexene with the yield of 85% (conversion 93%, selectivity 92%). By means of variation of the reaction parameters, the limonene conversion can be adjusted within the range 40 - 90%. The selectivity to 1-methyl-4-[alpha-methoxy-isopropyl]-l-cyclohexene always remains at about 95%. 

All these flow types appear more or less in a series one after the other during the evaporation of a liquid in a vertical tube, as Fig. 4.30 illustrates. The structure of a non-adiabatic vapour-liquid flow normally differs from that of an adiabatic two-phase flow, even when the local flow parameters, like the mass flux, quality, etc. agree with each other. The cause of this are the deviations from thermodynamic equilibrium created by the radial temperature differences, as well as the deviations from hydrodynamic equilibrium. Processes that lead to a change in the flow pattern, such as bubbles coalescing, the dragging of liquid drops in fast flowing vapour, the collapse of drops, and the like, all take time. Therefore, the quicker the evaporation takes place, the further the flow is away from hydrodynamic equilibrium. This means that certain flow patterns are more pronounced in heated than in unheated tubes, and in contrast to this some may possibly not appear at all. 

For values of parameters j/ and ( ), see Figure 12.65. Berl saddle parameters are apphcable to ceramic Intalox saddles—but not to metal Intalox saddles, which have a quite different geometry and are of the through-flow type covered by Wagner et al. ... 

FIGURE 11.8 The effect of the viscosity ratio, drop over continuous phase inn/tlc), on the critical Weber number for drop breakup in various types of laminar flow. The parameter a is a measure of the amount of elongation occurring in the flow for a — 0, the flow is simple shear for a — 1, it is purely (plane) hyperbolic. 

Column type Minimum reduced plate height Minimum reduced velocity Flow resistance parameter Separation impedance... 

Now in integrated circuits aspire to use objects, which have the sizes in hundreds nanometers and less, therefore a new methods of surface modification are necessary. One of perspective methods is an action of compression plasma flow on a silicon surface. Advantages of MPC as compared to other types of accelerators are high stability of compression flows generated, capability to control composition and dimensions of the flow and parameters of plasma. The discharge duration is large enough for practical applications [1]. Ona surface of silicon samples processed compression plasma flow surface structures cylindrical form [1] had been found. 

Three main types of elongational flow are uniaxial, biaxial, and planar. Although resistance to flow can be referred to loosely as an elongational or extensional viscosity (which further depends upon the type of elongational flow), this parameter generally is not constant. 

In the early days of tuneable diode laser spectroscopy, as is true for many modem-day applications, the experimental set-up of a TDLAS system was comprised of a gas cell as its centrepiece. This sampled the analyte across a closed volume allowing for the control of the internal and external parameters (e.g. ambient temperature, gas pressure in the cell, etc.). Then, flow-type systems were introduced later, in which the overall configuration was modified so that the gas could be continuously exchanged in a flow through the cell, normally assisted by a pump at the exit of the cell, as shown in Section 28.2. 

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