Heat Exchanger

A heat exchanger wherein:

• a core body is configured by turning up and bending a strip-shaped metal plate in a fanfold manner and forming turned-up end edges alternately at one end and then the other end of a rectangular planar portion, and has flat first flow channels and second flow channels alternately in the thickness direction of the metal plate;
• the first flow channels of the core body are blocked with slit blocks comprising long boards or bars at both the ends of each of said turned-up end edges, flat openings are formed only on one side, fins are interposed in said second flow channels, and thus a core is formed;
• the outer circumference of the core body is fitted in a tubular casing and thereby communication between adjacent turned-up end edges is blocked;
• a pair of ports for cooling water is formed at both the end portions of the casing on the side facing the side of said openings of said first flow channels;
• projecting stripes are bent and formed on the opposing planes in each of said first flow channels in proximity to and along said slit blocks at the positions opposing the ports, and gaps are formed between the respective projecting stripes;
• said cooling water is introduced into the respective first flow channels from said ports, and a part of said introduced cooling water is guided by said projecting stripes and passes through between the pair of opposing projecting stripes;
• and
• a fluid to be cooled is introduced from one cylindrical opening of said casing to the other opening through the respective second flow channels.