Patent ID: 7121331

Claim:
A heat exchanger comprising: a plate-shaped heat exchanger unit shaped to be substantially rectangular in plan view, the plate-shaped heat exchanger unit having a first planar fluid communication chamber defined therein; and a flat fin shaped similarly to the first planar fluid communication chamber and accommodated in the first planar fluid communication chamber, the flat fin having a first end provided with a first recess and a second end opposing to the first end and provided with a second recess, wherein the first recess comprises a first circular opening formed in a vicinity of an edge of the first end and a first cutout part that extends from the first circular opening to the edge of the first end, and the second recess comprises a second circular opening formed in a vicinity of an edge of the second end and a second cutout part that extends from the second circular opening to the edge of the second end, thereby allowing a first fluid, which has been introduced into the first planar fluid communication chamber through the first recess, to flow along an edge of the first and second ends.