Fins are used on all air coolers, dry coolers, evaporators
Fins increase the heat transfer of an air cooler. Fins are used on all air coolers, dry coolers, evaporators and condensers that transfer energy from a primary coolant or liquid media to air, although in some situations the air may be so unclean that there is a risk of blockage.
Fins consist of thin metal plates, 0.12–0.5 mm thick, which are fixed to an air cooler, dry cooler, evaporator or condenser. The fins are normally made of aluminium, which has good heat conductivity.
Heat transfer from metal to air is less effective than from liquid to metal, so the fins are used to increase the overall surface area and thus compensate for the metal-to-air inefficiency.