TEMA designations of Heat Exchangers
Tubular Exchangers Manufacturers Association
Because of the number of variations in mechanical designs for front and rear heads and shells, and for commercial reasons, TEMA has designated a system of notations that correspond to each major type of front head, shell type and rear head. The first letteridentifies the front head, the second letter identifies the shell type and the third letter identifies the rear head type.
Removable bundle exchangers
Removable bundle exchangers give the customer the ability to replace the tube bundle without replacing the shell or Bonnets. They are generally less cost effective than non removable designs.
BEU/AEU- U Bundle Exchangers are generally the most cost effective design style of removable bundle exchanger. Tubes may be water blasted, steam or chemically cleaned. These units must have an even number of tube passes, sometimes limiting their applicability to a service(e.g. they generally can not be used when a temperature cross occurs).
CEU- This design has the tubesheet welded to the Bonnet. You can remove the bundle from the shell, however to replace the bundle, the inlet Bonnet is included or you must cut off the tubesheet. Tubes may be chemically cleaned, water blasted or steam cleaned.
BEW/AEW- These are straight tube units with one floating head and one stationary head. The floating head is generally sealed with an O-Ring. These units are most often used as oil coolers or air coolers. Cleaning can be performed by either a chemical, mechanical method, water blast or steam cleaning.
AEP/BEP- These are straight tube units with one inside packed floating head and one stationary head. The floating head is generally sealed with packing. These units are most often used as intercoolers and aftercoolers with the gas on the tube side. They are also the most common style for oxygen service exchangers. These units have been used in services with tube side design pressures in excess of 2000 PSIG.
AES/AET- These units are the most expensive of the removable bundle designed units. The floating head is internal to the shell. Tubes can be cleaned mechanically , chemically, water blasted or steam cleaned. The design of these units forces an even number of tube side passes therefore they suffer the same service restrictions as U bundles. Although in theory one pass unit can be designed, this is rarely done. These units are generally used in services where U bundles are not desired and the service may be too corrosive/damaging to the packing used in AEP/BEP units.
More information:
http://www.wermac.org/equipment/heatexchanger_part5.html