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Table 3.1 - Features of shell and tube type exchangers
Shell and Tube Typical TEMA Advantages Limitations

Exchangers code

Fixed tube BEM, AEM, Provides maximum heat Shell side / out side of the tubes are
sheet NEN transfer area for a given inaccessible for mechanical
shell and tube diameter. cleaning. No provision to allow for

Provides for single and differential thermal expansion
multiple tube passes to developed between the tube and the
assure proper velocity. shell side. This can be taken care by

Less costly than providing expansion joint on the
removable bundle shell side.
designs.

Floating-head AEW, BEW, Floating tube sheet To provide the floating-head cover it
BEP, AEP, allows for differential is necessary to bolt it to the tube

AES, BES thermal expansion sheet. The bolt circle requires the
between the shell and the use of space where it would be
tube bundle. Both the possible to place a large number of

tube bundle and the shell tubes. Tubes cannot expand
side can be inspected and independently so that huge thermal

cleaned mechanically. shock applications should be
avoided. Packing materials produce
limits on design pressure and

temperature.
U-tube BEU, AEU U-tube design allows for Because of U-bend some tubes are

differential thermal omitted at the centre of the tube
expansion between the bundle. Because of U-bend, tubes
shell and the tube bundle can be cleaned only by chemical
as well as for individual methods. Due to U-tube nesting,

tubes. Both the tube individual tube is difficult to replace.
bundle and the shell side No single tube pass or true

can be inspected and countercurrent flow is possible.
cleaned mechanically. Tube wall thickness at the U-bend is
Less costly than floating thinner than at straight portion of the

head or packed floating tubes. Draining of tube circuit is
head designs. difficult when positioned with the

vertical position with the head side
upward.

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