Flow, fluid rates

Figure 10-32 shows the schematic of a pump, moving a fluid from tank A to tank B, both of which are at the same level. Tne only force that the pump has to overcome in this case is the pipe function, variation of which with fluid flow rate is also shown in the figure. On the other for the use shown in Figure 10-33, the pump in addition to pipe friction should overcome head due to difference in elevation between tanks A and B. In this case, elevation head is constant, whereas the head required to overcome fric tiou depends on the flow rate. Figure 10-34 shows the pump performance requirement of a valve opening and closing. 

Fluidization occurs when the fluid flow rate is great enough so that the pressure drop across the bed equals the weight of the bed. As stated previously, the solids film thickness adjacent to the wall is difficult to measure and/or predict. Wen and Fan [Chem. Eng., 64(7), 254 (1957)] give external walls ... 

FIG. 11 96 Balance points of compressor and condenser determines performance of condensing unit for fixed temperature of condenser cooling fluid (flow rate and heat-transfer coefficient are constant). 

The galvanic potential of metals can vary in response to environmental changes such as changes in fluid chemistry, fluid-flow rate, and fluid temperature. For example, at ambient temperatures steel is noble to zinc (as in galvanized steel). In waters of certain chemistries, however, a potential reversal may occur at temperatures above 140°F (60°C), and the zinc becomes noble to the steel. 

An accident sequence source term requires calculating temperatures, pressures, and fluid flow rates in the reactor coolant system and the containment to determine the chemical environment to which fission products are exposed to determine the rates of fission product release and deposition and to assess the performance of the containment. All of these features are addressed in the... 

For a fixed value of pressure drop, the fluid flow rate is approximately proportional to the size of the overflow diameter. A reduction in the overflow diameter leads to an increase in the pressure drop over the cyclone in order to keep the fluid flow rate unchanged. When the fluid flow rate is fixed, then, in general, the reduction in the size of the overflow diameter results in an increase in efficiency. This is simply because a small outlet opening makes it difficult for the particles to penetrate the cyclone. 

For a cyclone of fixed dimensions, the collection efficiency may be improved by increasing the fluid flow rate through the cyclone. As a consequence of this, the pressure drop over the cyclone increases. It can be shown that the relationship between the cut-off diameter and the fluid flow rate Q may be approximated as follows ... 

Hot wire anemometer An instrument for the measurement of fluid velocity by measuring the resistance of a fine platinum or nichrome wire, which may or may not be shielded by a silica tube. The wire resistance is proportional to the temperature and the fluid flow rate. 

When the downstream pressure is less than (or below) the critical or choked pressure, the velocity and fluid flow rate at a restriction or throat wall not/cannot be increased by lowering the downstream pressure further, and the fluid velocity at the restriction or throat is the velocity of sound at the conditions [29]. 

It was indicated earlier that the cathodic current was a poor indicator of adequate protection. Whilst, to a first approximation the protection potential is a function of the metal, the current required for protection is a function of the environment and, more particularly, of the cathodic kinetics it entails. From Fig. 10.4 it is apparent that any circumstance that causes the cathodic kinetics to increase will cause both the corrosion rate and the current required for full (/") or partial (1/ — /, ) protection to rise. For example, an increase in the limiting current in Fig. 10.5 produced by an increase in environmental oxygen concentration or in fluid flow rate will increase the corrosion rate and the cathodic protection current. Similarly, if the environment is made more acid the hydrogen evolution reaction is more likely to be involved in the corrosion reaction and it also becomes easier and faster this too produces an increased corrosion rate and cathodic current demand. 

The heat-exchange during the process is computed using data collected from the process fluid (flow rate and temperature variation). 

The catalytic reaction can be conveniently divided into a number of sequential steps, all of which impact on the overall efficiency of the reaction. First the reactants must diffuse to the catalyst surface the rate of diffusion depends on several factors including fluid density, viscosity and fluid flow rate. Whilst some reaction will take place at the external surface, the majority of reactants will need to diffuse into the internal pores. For a... 

Eredictions. A rotating cyhnder within a cyhnder electrode test system as been developed that operates under a defined hydrodynamics relationship (Figs. 25-15 and 25-16). The assumption is that if the rotating electrode operates at a shear stress comparable to that in plant geometry, the mechanism in the plant geometty may be modeled in the laboratory. Once the mechanism is defined, the appropriate relationship between fluid flow rate and corrosion rate in the plant equipment as defined by the mechanism can be used to predict the expected corrosion... 

The pressure drop in a pipe, due to friction, is a function of the fluid flow-rate, fluid density and viscosity, pipe diameter, pipe surface roughness and the length of the pipe. It can be calculated using the following equation ... 

The static pressure difference will be independent of the fluid flow-rate. The dynamic loss will increase as the flow-rate is increased. It will be roughly proportional to the flow-rate squared, see equation 5.3. The system curve, or operating line, is a plot of the total pressure head versus the liquid flow-rate. The operating point of a centrifugal pump can be found by plotting the system curve on the pump s characteristic curve, see Example 5.3. 

Define the duty heat-transfer rate, fluid flow-rates, temperatures. 

R is equal to the shell-side fluid flow-rate times the fluid mean specific heat divided by the tube-side fluid flow-rate times the tube-side fluid specific heat. 

If the specification is incomplete, determine the unknown fluid temperature or fluid flow-rate from a heat balance. 

An alternative to the stirred tank system is a column-type device which provides for constant fluid flow through a powder bed. The mass transport process was shown to be primarily determined by the length and cross-sectional area of the cylinder and the fluid flow rate [36],... 

The Bernoulli equation relates the pressure drop across the bed to the fluid flow rate and the bed properties ... 

A laminar-flow reactor (LFR) is rarely used for kinetic studies, since it involves a flow pattern that is relatively difficult to attain experimentally. However, the model based on laminar flow, a type of tubular flow, may be useful in certain situations, both in the laboratory and on a large scale, in which flow approaches this extreme (at low Re). Such a situation would involve low fluid flow rate, small tube size, and high fluid viscosity, either separately or in combination, as, for example, in the extrusion of high-molecular-weight polymers. Nevertheless, we consider the general features of an LFR at this stage for comparison with features of the other models introduced above. We defer more detailed discussion, including applications of the material balance, to Chapter 16. 

Mechanical forces such as shear and surface tension affect enzyme activity by disturbing the shape of the enzyme molecule. Since the shape of the active site of the enzyme is specifically engineered to correspond to the shape of the substrate, even small changes in structure may drastically affect enzyme activity. Consequently, fluid flow rates, stirrer speeds, and foaming must be carefully controlled in order to ensure that an enzyme s productivity is maintained. 

Determine the values of the tank volumes (really residence times of the component) in each of the four tanks for steady-state operation with a fixed fluid flow rate of q so as to maximize the yield of pipduct C4. Note (V/qt) = 0 5 the residence time. Use the following data for the coefficients in the problem... 

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