A core structure of an integral heat-exchanger comprises at least two first heat
exchanger tubes which extend in parallel with each other; at least two second heat
exchanger tubes which extend in parallel with each other, the second heat exchanger
tubes juxtaposed with the first heat exchanger tubes; and a corrugated fin including
a corrugated first part interposed between the first heat exchanger tubes, a corrugated
second part interposed between the second heat exchanger tubes and a flat connection
part arranged between the corrugated first and second parts. The corrugated first
part of the fin is formed with a plurality of first louvers each extending substantially
between the two first heat exchanger tubes. The corrugated second part of the fin
is formed with a plurality of second louvers each extending substantially between
the two second heat exchanger tubes. The innermost one of the second louvers is
positioned away from the innermost end of the corrugated second part of the fin
by a given length. The flat connection part is formed with a third louver in the
vicinity of the innermost one of the first louvers. The third louver is constructed
to obstruct a heat transfer in the fin.
