| 摘要 |
A double-pipe heat exchanger that is easy to manufacture, and the whole thereof is smoothly bent to serve as a part of piping, and that provides high pressure resistance, wherein an inner tube 1 has a section orthogonal to an axis line thereof in which a plurality of swollen portions 7a in a bladder-like or balloon-like shape in section are formed in a radial direction from the center, mouths of these swollen portions 7a are closed, and the tip ends of respective swollen portions 7a are in contact with the inner surface of an outer tube 2. |
