| 摘要 |
PURPOSE:To obtain the heat transfer tube of titanium, which is prevented from stress concentration of annular protuberance and improved in the rigidity thereof, by a method wherein a plural rails of axial protuberances, intersecting orthogonally to the annular protuberances of inner surface of the tube, are provided in the heat transfer tube. CONSTITUTION:The annular protuberances 11 are arranged axially on the inner wall of main body 10 of the tube with constant spaces. The annular protuberances 11 are formed so as to have vertical surfaces 12 in order to improve the overall heat-transfer coifficient efficiently and slanted surfaces 13 are formed from the vertical surfaces 12 toward the downstream side of heat medium. Four rails of axial protuberances 14 are formed axially along the inner wall of main body 10 of the tube. The section of the axial protuberance 14 is circular and is connected to the inner wall of the tube main body 10 smoothly with a curvature (r). In case the impact force of steam or the like, for example, is exerted vertically on the outer periphery of the heat transfer tube of titanium of such constitution, the impact force may be supported by the axial protuberances of the tube and, as a result, the stress concentration, effecting on the roots of vertical surfaces 12 of the annular protuberances 11, may be mitigated. |
