Heat double-tube-type

Figure 5.1 shows, conceptually, four commonly used types of heat transfer equipment, although many more refined designs of such equipment exist. On a smaller scale, a double-tube type is used, whereas on an industrial scale a shell-and-tube type heat exchanger is frequently used. 

Figure 5.1 Few common types of heat exchangers, (a) Double-tube type (b) shell-and-tube type (c) coil-type and (d) plate-type.

Thus, d for a narrow space between two parallel plates, of which b is sufficiently large compared withz, is almost equal to 2z. Values offluid flow through the annular space between the outer and inner tubes of the double tube-type heat exchanger or fluid flow outside and parallel to the tubes of multitubular heat exchanger can be calculated using Equation 5.11. 

Calculate the equivalent diameter of the annular space of a double tube-type heat exchanger. The outside diameter of the inner tube d is 4.0 cm and the inside diameter of the outer tube is 6.0 cm. 

MUk, flowing at 20001 h through the stainless steel inner tube (40 mm i.d., 2 mm thick) of a double tube-type heater, is to be heated from 10 to 85 °C by saturated steam condensing at 120 °C on the outer surface of the inner tube. Calculate the total length of the heating tube required. 

Heat exchangers, other than the welded double-concentric-tube type or double-tube sheet type, must employ a pressure differential and a means for monitoring the differential. The pressure differential shall be such that the fluid requiring a higher microbial quality shall be that with the greater pressure. Written records of the pressure differential monitoring shall be maintained as required in 212.183... 

The spiral-wound fabrication shown in Figure 1.3 is analogous to a single tube-in-tube or double-pipe heat exchanger. The hollow-fiber concept lends itself to the shell-and-tube type of heat exchanger. The hollow fibers are mounted as a tube bundle inside a shell, as indicated in Figure 1.4. A few applications are indicated in Figure 1.5. 

In the vei tical-tube single-row double-fired heater, a single row of vertical tubes is arrayed along the center plane of the radiant section that is fired from both sides. Usually this type of heater has an overhead horizontal convec tion bank. Although it is the most expensive of the fired heater designs, it provides the most uniform heat transfer to the tubes. Duties are 21 to 132 GJ/h (20 to 125 10 Btu/h) per cell (twin-cell designs are not unusual). 

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