Tubes in pressure drop

The Sieder and Tate equation for the pressure drop in tubes is... 

A convenient chart for water pressure drop in tubes is given in Figure 10-138. 

If rheological flow curve data are available (as in Fig. 3-16), we can directly compute the pressure drop in tube flow as well as determine the velocity profile and flow rate. 

Apb Pressure drop in tube filled with particles (fixed bed etc.) Pa... 

FIGURE 13.2 Scheme for calculation of pressure drop in tube. 

From the above plot, it can be seen that the recovery factor for gas reservoirs depends upon how low an abandonment pressure can be achieved. To produce at a specified delivery pressure, the reservoir pressure has to overcome a series of pressure drops the drawdown pressure (refer to Figure 9.2), and the pressure drops in the tubing, processing facility and export pipeline (refer to Figure 9.12). To improve recovery of gas, compression facilities are often provided on surface to boost the pressure to overcome the pressure drops in the export line and meet the delivery pressure specified. 

Pressure drop in static mixers depends very strongly on geometric arrangement of the inserts. It is simply defined in relation to the pressure drop AP in an empty tube given by Darcy s equation ... 

The fluid dehvery in an air-spray system can be pressure or suction fed. In a pressure-fed system, the fluid is brought to the atomizer under positive pressure generated with an external pump, a gas pressure over the coating material in a tank, or an elevation head. In a suction system, the annular flow of air around the fluid tip generates sufficient vacuum to aspirate the coating material from a container through a fluid tube and into the air stream. In this case, the paint supply is normally located in a small cup attached to the spray device to keep the elevation differential and frictional pressure drop in the fluid-supply tube small. 

The shape of the coohng and warming curves in coiled-tube heat exchangers is affected by the pressure drop in both the tube and shell-sides of the heat exchanger. This is particularly important for two-phase flows of multicomponent systems. For example, an increase in pressure drop on the shellside causes boiling to occur at a higher temperature, while an increase in pressure drop on the tubeside will cause condensation to occur at a lower temperature. The net result is both a decrease in the effective temperature difference between the two streams and a requirement for additional heat transfer area to compensate for these losses. 

Pressure drop in the tube can be expressed with the use of the friction factor from the Ergun equation ... 

Calculation of Tubeside Pressure Drop in Shell and Tube Exchangers... 

Common to all air cooled heat exchangers is the tube, through which the process fluid flows. To compensate for the poor heat transfer properties of air, which flows across the outside of the tube, and to reduce the overall dimensions of the heat exchanger, external fins are added to the outside of the tube. A wide variety of finned tube types are available for use in air cooled exchangers. These vary in geometry, materials, and methods of construction, which affect both air side thermal performance and air side pressure drop. In addition, particular... 

Firebox Overpressure - The firebox of a forced-draft furnace and boiler is designed to withstand the overpressure that can be generated by the fans with dampers in their closed position. This needs to be specially checked when both forced and induced-draft fans are provided to discharge combustion products through heat recovery facilities, since higher than normal fan pressures may be used to overcome pressure drop. In the case of high-pressure process furnaces, a tube rupture could also be the cause of firebox overpressure. 

Chilton, T. H. and A. P. Colburn, Heat Transfer and Pressure Drop in Empty Baffled and Packed Tubes, Part II, Pressure Drop in Packed Tubes, Trans. Am. Inst. Chem. Engrs. 26, 178, 1931,... 

When a fluid flows over a stationary or moving surface, the pressure of the fluid decreases along the length of the surface due to friction. This is commonly called the pressure drop of the system. Of particular interest are the pressure drops in pipes (tubes) and in heat exchanger shells. 

Figure 10-142. Pressure drop in fluid flowing across tube banks with segmental baffles. (Used by permission Buthod, A. P. Oil Gas Journal, V. 58, No. 3, 1960. PennWell Publishing Company. All rights reserved.)...

Pressure Drop in Exchanger Shells Using Bundles ofLoxv-Fin Tubes... 

At a 12.5 psi pressure drop in water to water applications, the surtoce heat transfer rote achieved in a Graham plate exchanger exceeds that of a shell and tube unit by a factor of 3.4. Similar or higher improvement toctors are obtained with other fluids. 

Calculate tube-side pressure drop in usual manner, including loss in headers. 

Pressure drop in heat exchangers Tube-side... 

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