Heat exchanger and dimple tube used in the same, the tube having larger opposed protrusions closest to each end of tube

摘要

A heat exchanger employing a dimple tube is disclosed, in which sufficient strength is provided by improving the processing accuracy of the dimple tube and decreasing the processing error. The tube comprises a plate folded in two so as to make two edges of the plate contact each other and form a flat tube. The plate comprises protrusions provided on each inner wall of the flat tube in a manner such that the heads of opposed protrusions on both the inner walls contact each other. The plate is clad with a brazing filler metal and the protrusions are formed on a surface of the plate before the plate is folded, and the two edges of the plate and the heads of the opposed protrusions are respectively brazed after the plate is folded. A predetermined number of sets of the opposed protrusions, positioned closest to the end of the tube, are larger than the other protrusions in a manner such that their size along the longitudinal direction of the tube is larger.