Section 3. INTERCOOLERS AND AFTERCOOLERS
1 DESCRIPTION. Intercoolers and aftercoolers are heat exchangers employed to
dissipate the heat generated in compression. There are two types of heat
exchangers used on air compressors, air-cooled and water-cooled.
1.1 Air-Cooled Heat Exchanger. Air-cooled heat exchangers are most often
used on small compressors. The air-cooled heat exchanger is a finned, tubular
radiator (figure 4-3).
1.2 Water-Cooled Heat Exchanger. The most common design of water-cooled heat
exchangers, shell and tube type, consists of a single bundle of tubes enclosed
inside a cylindrical shell (figure 4-4). The air to be cooled passes through
the tubes while the water passes over the tubes. Baffles are often provided
in the tube bundle to direct the waterflow across the heat exchanger tubes in
the most efficient manner.
(a) The intercooler is located between the discharge of one cylinder and
the intake of the next cylinder of multistage compressors. The intercooler
reduces the temperature and the volume of the compressed air for delivery to
the next compression stage.
(b) The aftercooler is located at the discharge of the last cylinder to
cool the air, reduce its volume, and to liquify any condensable vapors.
FIGURE 4-3. Air-Cooled Heat Exchanger