Exit losses

Expansion and Exit Losses For ducts of any cross section, the frictional loss for a sudden enlargement (Fig. 6-13c) with turbulent flow is given by the Borda-Carnot equation ... 

Equation (6-95) is valid for incompressible flow. For compressible flows, see Benedict, Wyler, Dudek, and Gleed (J. E/ig. Power, 98, 327-334 [1976]). For an infinite expansion, A1/A2 = 0, Eq. (6-95) shows that the exit loss from a pipe is 1 velocity head. This result is easily deduced from the mechanic energy balance Eq. (6-90), noting that Pi =pg. This exit loss is due to the dissipation of the discharged jet there is no pressure drop at the exit. 

Contributing to f are losses for the entrance to the pipe, the three sections of straight pipe, the butterfly valve, and the 90 bend. Note that no exit loss is used because the discharged jet is outside the control volume. Instead, the V v2 term accounts for the kinetic energy of the discharging stream. The Reynolds number in the pipe is... 

The pressure drop through a settling chamber is small, consisting primarily of entrance and exit losses. Because low gas velocities are used, the chamber is not subject to abrasion and may therefore be used as a precleaner to remove very coarse particles and thus minimize abrasion on subsequent equipment. 

Exit ioss. The exit loss assumes that one-half of the kinetic energy leaving the vaned diffuser is lost. 

The advantage of a stage with greater than 50% reaetion is the low exit loss resulting from lower axial veloeity and blade speeds. Beeause of the... 

Exit loss. This loss is due to the kinetie energy head leaving the stator. 

Exit loss. The fluid leaving a radial-inflow turbine constitutes a loss of about one-quarter of the total exit head. This loss varies from about 2-5%. 

When dealing with water treatment applications you carmot avoid pipe flow calculations. We have a pipeline in which the throughput capacity of 500 Liter/sec. The flow is split into two pipelines and the inside diamter of the pipe is 350 mm. The length of the pipeline is 55 m. The entry loss is 0.70 and the exit loss is 1.00. There are two 45° bends and two 90° bends in the lines, (a) Determine the flow per pipe (b) determine the line velocity (c) determine the resulting hydraulic loss in meters. 

Determine expansion or contraction losses, if any, including tank or vessel entrance or exit losses from Figures 2-12A, 2-15, or 2-16. Convert units to psi, head loss in feet times 0.4331 = psi (for water), or adjust for Sp Gr of other liquids. 

K = total resistance coefficient of pipe, valves, fittings, and enuance and exit losses in the line... 

Tabulate the summation of equivalent lengths of straight pipe, valves, fittings, entrance/exit losses as presented in earlier sections of this chapter. 

Note When P is expressed in absolute pressure units, hswill be in absolute units. If P Is less than atmospheric pressure P is (-) If expressed as a gauge reading and will be a negative feet of liquid. P is (-(-) if expressed in absolute units. The friction loss hs Includes any entrance or exit losses and other such fittings in the system. 

The friction lasses from the pump to the vessel include any entrance or exit losses. Unless velocities ore high,these lasses ore usually negligible. 

The friction losses for fluid flow in pipe valves and fittings are determined as presented in Chapter 2. Entrance and exit losses must be considered in these determinations, but are not to be determined for the pump entrance or discharge connections into the casing. 

The values of friction loss (including entrance, exit losses, pressure drop through heat exchangers, control valves and the like) are hjL and h L. The total static head is D — Sl, or [(D -f D ) — (—Sl)] if siphon action is ignored, and [(D + D ) — (S l)] for worst case, good design practice. 

Note that this pressure loss does not account for nozzle entrance or exit losses. These losses may be neglected provided velocities are low and no unusual conditions are imposed upon these connections. For low pressure systems, these losses cannot be ignored. 

For bundle entrance and exit losses, refer to copyrighted graph of Donohue. ... 

Assume the 3% pressure loss (1% due to entrance and exit losses plus 2% due to intercooler and piping losses). Suction pressure at second case ... 

Table 19.4 Allowances for fittings and entrance and exit losses in pipes...

For most duties, the fluids have to make fewer passes across the plates than would be required through tubes or in passes across the shell. Since a plate unit can carry out the duty with one pass for both fluids in many cases, the reduction in the number of required passes means less pressure lost due to entrance and exit losses and consequently more effective use of the pressure. 

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