Abstract: The method for manufacturing heat exchanger elements includes the steps of forming an open tubular base body having a longitudinal extension having a width that is substantially greater than the height thereby defining narrow and wide sides of the tubular base body. In the longitudinal extension of the tubular base body a longitudinal opening with longitudinal edges remains. Two strips of sheet metal are removed from a supply roll and corrugated to form corrugated sheet metal strips. The open tubular base body and the corrugated sheet metal strips are advance continuously and parallel to one another in the direction of the longitudinal extension through a fastening device such that the wide sides face the corrugated sheet metal strips. The corrugated sheet metal strips are pressed onto the wide sides and then fastened to the wide sides at some locations of contact between the wide sides and the of corrugated sheet metal strips.

Abstract: A heat exchanger has a plurality of parallel heat exchanger tubes with two plane sides and two narrow sides. The heat exchanger tube has a contour with a width and a height in a direction of flow of a first heat-exchanging medium such that the width is much greater than the height. Ribs are connected to the plane sides of the heat exchanger tubes. The ribs are made of a rib band folded to a meander-shape with bent portions. Adjacent ones of the ribs form a flow cross-section for a second heat-exchanging medium. The ribs have a plurality of openings wherein the size of the opening is at least equal in size to the size of the flow cross-section between adjacent ribs.