Core structure of heat exchanger

Abstract: A core structure includes a plurality of flat tubes and a plurality of corrugated inner fins. Each corrugated inner fin has top portions for being fixed to an inner surface of an upper wall portion of the tubes, bottom portions for being fixed to an inner surface of a lower wall portion thereof, and slanted portions for connecting the top portion with adjacent bottom portions thereof. The corrugated inner fin has first corrugations located at both end sides of the corrugated inner fin and second corrugations located between the first corrugations, where the first and the second corrugations has the top portion and the adjacent slanted portions and project from the bottom portions. The first corrugations are set to be smaller in a front-back directional length of the corrugated inner fin than a front-back directional length of the second corrugations.