Fluid Conditions

Most flow meters are designed and caHbrated for use on turbulent flow, by far the more common fluid condition. Measurements of laminar flow rates may be seriously in error unless the meter selected is insensitive to velocity profile or is specifically caHbrated for the condition of use. 

Variable-Area Flow Meters. In variable-head flow meters, the pressure differential varies with flow rate across a constant restriction. In variable-area meters, the differential is maintained constant and the restriction area allowed to change in proportion to the flow rate. A variable-area meter is thus essentially a form of variable orifice. In its most common form, a variable-area meter consists of a tapered tube mounted vertically and containing a float that is free to move in the tube. When flow is introduced into the small diameter bottom end, the float rises to a point of dynamic equiHbrium at which the pressure differential across the float balances the weight of the float less its buoyancy. The shape and weight of the float, the relative diameters of tube and float, and the variation of the tube diameter with elevation all determine the performance characteristics of the meter for a specific set of fluid conditions. A ball float in a conical constant-taper glass tube is the most common design it is widely used in the measurement of low flow rates at essentially constant viscosity. The flow rate is normally deterrnined visually by float position relative to an etched scale on the side of the tube. Such a meter is simple and inexpensive but, with care in manufacture and caHbration, can provide rea dings accurate to within several percent of full-scale flow for either Hquid or gas. 

M. E. Paulaitis and co-workers, eds.. Chemical Engineering at Supercritical-Fluid Conditions, Ann Arbor Science PubHshers, Mich., 1983. 

Runaway reaction or polymerization—e.g., vinyl chloride monomer (Kim-E and Reid, The Rapid Depressurization of Hot, High Pressure Liquids or Supercritic Fluids, chap. 3, in M. E. Paulaitis et al., eds.. Chemical engineering at Supercritical Fluid Conditions, Ann Arbor Science, 1983, pp. 81-100)... 

In the absence of factual corrosion information for a particular set of fluid conditions, a reasonably good selection would be possible from data based on the resistance of materials to a very simifar environment. These data, however, should be used with some reservations. Good practice calls for applying such data for preliminary screening. Materials selected thereby would reqmre further study in the fluid system under consideration. 

Convert the free air rates to the proper product in the tanks using the corrections outlined in a previous paragraph. Keep in mind that the manufacturer s rating tables are in free air however, the actual process calculations provide flows in terms of the actual liquids at actual temperatures and pressures. It is important that the manufacturer be given the actual fluid conditions to ensure proper capacity rating. 

For a given fluid condition and assumed size of reboiler, evaluate physical property factor c )i from Figure 10-107A and physical property factor from Figure 10-107B. 

Except for fluid conditions of possible galvanic corrosion, the tins can be any selected material, not necessarily the same as the tube. Some usable tin and/or tube materials are... 

This reaction occurs over a wide range of drilling fluid conditions. 

Figure 8.16 (Fluid -+- fluid) phase diagram for a near-ideal system. Reproduced with permission from W. B. Streett, Chapter 1 in Chemical Engineering ai Supercritical Fluid Conditions, M. E. Paulaitis, J. M. L. Penninger. R. D. Gray Jr., and P. Davidson, editors, Ann Arbor Science Press. Michigan, 1983.

For the flow of a compressible fluid, conditions of sonic velocity may be reached, thus limiting the maximum flowrate for a given upstream pressure. This situation can also occur with two-phase flow, and such critical velocities may sometimes be reached with a drop in pressure of only 30 per cent of the inlet pressure. 

While electrical conductivity, diffusion coefficients, and shear viscosity are determined by weak perturbations of the fundamental diffu-sional motions, thermal conductivity is dominated by the vibrational motions of ions. Heat can be transmitted through material substances without any bulk flow or long-range diffusion occurring, simply by the exchange of momentum via collisions of particles. It is for this reason that in liquids in which the rate constants for viscous flow and electrical conductivity are highly temperature dependent, the thermal conductivity remains essentially the same at lower as at much higher temperatures and more fluid conditions. 

ORNL small-break LOCA tests Experimental investigation of heat transfer and reflood analysis was made under conditions similar to those expected in a small-break LOCA. These tests were performed in a large, high-pressure, electrically heated test loop of the ORNL Thermal Hydraulic Test Facility. The analysis utilized a heat transfer model that accounts for forced convection and thermal radiation to steam. The results consist of a high-pressure, high-temperature database of experimental heat transfer coefficients and local fluid conditions. 

The minimum DNB ratio is evaluated at the hottest fuel rod in the hottest flow channel of the core. The fluid conditions in the hottest flow channel of an open-channel PWR should be realistically evaluated by considering the cross-channel... 

Subtracting matter, by cutting, chipping, or carving, for example, provides a way to shape solid materials into objects. Many objects are not shaped by the subtraction of matter, however, but are either cast or wrought cast objects are shaped when the material used to make them, such as glass, plaster of Paris, or bronze, is in a fluid condition. Wrought objects, on the... 

The critical velocity depends on particle radius, particle composition fluid medium, and fluid conditions such as solution pH and ionic strength. 

Porous property of these particles was considered to be based on crystallization mechanism of calcium phosphate, in which fine crystals formed in the bottom of fluidized bed attached to the fluidized seeds by driving force of supersaturation and fluid conditions. 

For experimental determination of diffusion coefficients, a large database is already available. Nonetheless, data for specific applications are often difficult to find because the data may not cover the right temperature range, mineral compositions, or fluid conditions. In geospeedometry applications, data often must be extrapolated to much lower temperatures and the accuracy of such extrapolation is difficult to assess. Because the timescale of geological processes is often in the order of Myr, and that of experiments is at most years, instrumental methods to measure very short profile are the key for the determination of diffusion coefficients that are applicable to geologic problems. 

Under the (fluid) conditions necessary to promote photoassociation, the excimer fluorescence is rotationally depolarized however, measurements of pyrene crystal fluorescence have confirmed81 the predicted direction of polarization along the major axis. 

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