Heat exchanger core

A heat exchanger core comprising:

• plurality of flat plate parts formed by alternately folding back a single belt-like metal plate in a zigzag fashion at a first fold-back edge and at a second fold-back edge;
• a plurality of element parts formed by joining peripheral edges of a pair of adjoining flat plate parts which are integrally coupled to each other at said first fold-back edge, adjoining ones of said plurality of element parts being integrally coupled at a certain interval to each other at said second fold-back edge;
• a pair of ports for a first fluid formed at positions apart from each other at the peripheral edge of each of said plurality of element parts, wherein a second fluid flows over an outer surface side of said plurality of element parts and a planar surface of each of said plurality of flat plate parts is bent into a corrugation to form a corrugated bent part, with said pair of ports of each element part being formed at said second fold-back edge, external surfaces of said corrugated bent parts of adjoining element parts being in back-to-back contact with one another;
• and
• a manifold part associated with said ports, said manifold part extending from said second fold-back edge to said first fold-back edge or its vicinity, said manifold part being bent into a corrugation to form auxiliary corrugated bent parts and such that the amplitude of said corrugation is smaller than the amplitude of corrugations of the other parts, external surfaces of said auxiliary corrugated bent parts of adjoining element parts being in back-to-back contact with one another.