Casing baffles

For unbaffled case with cods use 0.65 of h calculated for baffled case (29). 

Large areas such as the shock pads of artificial sports surfaces can experience very considerable dimensional changes due to temperature. In one particularly baffling case artificial grass appeared to expand and formed waves when the temperature was lowered. The effect was found to be a result of internal stresses and the differential expansion between the grass and the mbber shock pad. 

In investigating an in-service failure, the analyst must consider a broad spectrinn of possibilities or reasons for its occurrence. Often a large number of factors must be understood in order to determine the cause of the original failure. The analyst is in the position of Sherlock Holmes attempting to solve a baffling case. Like the great detective, the analyst must carefully examine and evaluate all evidence available and prepare a hypothesis or a model of the chain of events that could have caused the crime. If the failure can be duplicated under controlled simulated service conditions in the laboratory, much can be learned about how the failure actually occurred. 

In the case of a packed column, the terms on the right-hand side should each be divided by the voidage, ie, the volume fraction not occupied by the soHd packing (71). In unpacked columns at low values of the sHp velocity approximates the terminal velocity of an isolated drop, but the sHp velocity decreases with holdup and may also be affected by column internals such as agitators, baffle plates, etc. The sHp velocity can generally be represented by (73) ... 

A numerical study of the effect of area ratio on the flow distribution in parallel flow manifolds used in a Hquid cooling module for electronic packaging demonstrate the useflilness of such a computational fluid dynamic code. The manifolds have rectangular headers and channels divided with thin baffles, as shown in Figure 12. Because the flow is laminar in small heat exchangers designed for electronic packaging or biochemical process, the inlet Reynolds numbers of 5, 50, and 250 were used for three different area ratio cases, ie, AR = 4, 8, and 16. 

The feed gas is iatioduced neai the lotoi axis. Enriched and depleted gases are extracted by stationary pitot-like scoops. The location and shape of these tubes, and the baffles within the rotor, gready effect the gas dow which recirculates within the rotor, reaching enrichment equiUbtium at a given feed rate. A vacuum is maintained around most of the rotor. The UF leakage around the stationary axial post is confined to the top of the case by the use of a molecular pump. 

Baffles are provided for heat-transfer purposes. When shell-side baffles are not required for heat-transfer purposes, as may be the case in condensers or reboilers, tube supports are installed. 

Micro-scale variables are involved when the particles, droplets, baffles, or fluid chimps are on the order of 100 [Lm or less. In this case, the critical parameters usually are power per unit volume, distribution of power per unit volume between the impeller and the rest of the tanh, rms velocity fluctuation, energy spectra, dissipation length, the smallest micro-scale eddy size for the particular power level, and viscosity of the fluid. 

For Reynolds numbers greater than 2000 baffles are commonly used with turbine impelTers and with on-centerhne axial-flow impellers. The flow patterns illustrated in Figs. 18-15 and 18-16 are quite different, but in both cases the use of Baffles results in a large top-to-bottom circulation without vortexing or severely unbalanced fluid forces on the impeller shaft. 

Crystallizers with Fines Removal In Example 3, the product was from a forced-circulation crystallizer of the MSMPR type. In many cases, the product produced by such machines is too small for commercial use therefore, a separation baffle is added within the crystallizer to permit the removal of unwanted fine crystalline material from the magma, thereby controlling the population density in the machine so as to produce a coarser ciystal product. When this is done, the product sample plots on a graph of In n versus L as shown in hne P, Fig. 18-62. The line of steepest ope, line F, represents the particle-size distribution of the fine material, and samples which show this distribution can be taken from the liquid leaving the fines-separation baffle. The product crystals have a slope of lower value, and typically there should be little or no material present smaller than Lj, the size which the baffle is designed to separate. The effective nucleation rate for the product material is the intersection of the extension of line P to zero size. 

Draft-Tuhe (DT) Crystallizer This ciystaUizer may be employed in systems in which fines destruction is not needed or wanted. In such cases the baffle is omitted, and the internal circulator is sized to have the minimum nucleating influence on the suspension. 

Soft solids, most of which are biological waste such as sewage, are difficult to convey up the beach. Annular baffles or dams have been commonly used to provide a pool-level difference wherein the pool is deeper upstream of the baffle toward the clarifier and lower downstream of the baffle toward the beach. The pool-level difference across the baffle, together with the differential speed, provide the driving force to convey the compressible sludge up the beach. This has been used effectively in thickening of waste-activated sludge and in some cases of fine clay with dilatant characteristics. 

Deterioration of tubes near the inlet nozzle of condenser shells due to impingement of water and steam mixtures can be alleviated through the use of appropriately placed and sized baffles or impact plates or by applying clip-on impingement shields to the tubes (see Case History 11.3). 

Industry sets limits that bound our degrees of freedom and thus tend to shorten our design case study load. We are all aw are of such limits and this last category is included primarily for completeness. Examples include minimum industrial thickness for carbon steel plate, and maximum baffle cut for shell and tube heat exchangers. 

Sinee the reaetors were a series of baffled tanks, Case 1 is most likely. Case 2 ean be evaluated quantitatively by using the kineties applieable to the reaetion and making suitable ehanges to allow for the reeyeling of ethylene glyeol. Case 3 is extremely unlikely beeause the impurities formed are water-soluble and should, therefore, be removed by the water purged from the system. 

There are cases where W/D = 1/8 and J/D = 1/10 for some agitator correlations. Usually, 4 baffles are used and the clearance between the baffles and the wall is about 0.1-0.15 J. This ensures that the liquid does not form stagnant pockets between the baffle and the wall. The number of impeller blades varies from 4 to 16, but is generally between 6 and 8. 

This jacket is considered a special case of a helical coil if certain factors are incorporated into equations for calculating outside-film coefficients. In the equations at left and below, the equivalent heat transfer diameter D. for a rectangular cross-section IS equal to four times the width of the annular space, w and IS the mean or centerline diameter of the coil helix. Velocities are calculated from the actual cross-section of the flow area. pw. where p IS the pitch of the spiral baffle, and from the effective mass flowrate. W. through the passage. The leakage around spiral baffles is considerable, amounting to 35-50% of the total mass flowrate. The effective mass flowrate is about 60% of the total mass flowrate to the jacket W =... 

In this case, a controlled quantity of water is discharged against a rapidly rotating disk where centrifugal force spins the droplets radially against circumferentially placed baffles, producing a fine water mist which is discharged into the airstream. 

Complementary accessories for ATD components of the installation which are used in conjunction with, and in several cases form an integral part of, the air terminal device for the purpose of achieving the predetermined profile or rate of flow into or from the air terminal device (e.g., air flow controllers, dampers, flow equalizers, baffles, etc.), and... 

In this case foam can be re-entered into the mixture by this action, and solids or liquids added will enter the impeller rather rapidly. The deeper the liquid above the baffle the greater the rotating action. Bottom srvirling action allows the segregation of heavy solid particles [21]. 

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