| 摘要 |
PURPOSE:To prevent two fluids from mixing even if a part of an inner tube is corroded by a structure wherein grooves passing through along the direction of the axis line of the inner tube are provided between the inside tube of the inner tube and the outside tube of the inner tube. CONSTITUTION:In the double tube type heat exchanger consisting of a fluid passage 3 in the inner tube 12 and a fluid passage 4 formed as a gap between an outer tube 1 and the inner tube 12 inserted in the outer tube 1, the bare tube 12b is inserted into the internally grooved tube 12 and, after that, worked by drawing so as to form tightly contact portions 12c and vacant portions 12d between the tubes 12a and 12b. Said portions 12d pass through along the direction of the axis line of the inner tube 12 so as to communicate with the open air at both the ends 12e and 12f of the inner tube 12. As the inner tube 12 causes work-hardening at drawing, the inner tube 12 is annealed after drawing and then inserted in the outer tube 1 and, after that, the outer tube 1 and the inner tube 12 are simultaneously wound in serveral turns. Accordingly, even if the inner tube is corroded, one fluid does not mix with the other fluid. Furthermore, because the inner tube is annealed, the external size of the heat exchanger can be made smaller by bending. |
