Rectangular heat transfer duct for e.g. plate heat exchanger, has identical U-profiles reciprocally placed on each other and connected over entire length, where each profile includes left and right side pieces thicker than U-profile base

The duct (1) has identical U-profiles (2, 3) reciprocally placed on each other and connected over entire length. Each U-profile has left and right side pieces (4, 5) thicker than a U-profile base (6). Front surfaces of the side pieces include negative and positive contours (7, 8) e.g. concave and convex, corresponding to each other, and the U-profiles and/or side pieces are connected with each other in a form-fit manner by the contours. The negative contour is mirrored based on the positive contour about a central axis (13) of the side pieces. Die Erfindung betrifft einen Wärmeübertragungskanal mit rechteckigem Innenquerschnitt, bei dem der Rechteckkanal durch zwei Formstäbe ausgebildet ist, die aufeinander gelegt und über die gesamte Länge verbunden sind.