A fin is disclosed for use in a heat exchanger coils including tube segments
extending
through the fin. The fin includes a corrugated sheet of material having a plurality
of major corrugations, about 8 to about 24 corrugations per inch (2.54 cm), each
major corrugation being a peak or a valley with an amplitude "h" at the peaks or
the valleys perpendicular to a reference major plane equally bisecting the major
corrugations, and a width "w"; a plurality of orifices; a collar perpendicular
to the reference major plane and extending from the sheet around each of the orifices;
and a generally flat area that is generally parallel to or generally coextensive
with the reference major plane and that surrounds each collar. The major corrugations
have angled walls extending from at least one of the peaks and valleys to the generally
flat areas adapted to create a vortex when air travels over the fin. A ratio of
"h" to "w" is about 0.32 to about 0.7.
