| 摘要 |
PURPOSE:To obtain the heat transfer tube of a high performance and reduce the cost thereof by a method wherein the configurations of the grooves on the inner surface of the tube are changed in accordance with the positions of the tube. CONSTITUTION:First group II, consisting of a multitude of grooves 2 which are opened toward the center axis of the tube, and second group III, consisting of a multitude of grooves 3, whose apexes are narrow and the inner parts thereof are wide, are formed alternately and opposingly on the inner surface of the tube. These groove groups II, IIIare obtained by applying extracting and elongating process to an inner surface uniformly grooved metal tube obtained by a grooving process. The depth of the groove 2 of the first groove group II becomes deeper than the conventional groove by the choking and thickness increasing effect of the extracting and elongating process after the grooving process and the surface 26 of the chevron 25 becomes rough compared with the conventional groove whereby the heat transfer property of the pipe is improved. The inner part of the groove 3 of the second groove group III is wider and the apex 30 thereof is narrower than the conventional groove whereby the area of the chevron permitted to contact with a fluid is increased and the heat transfer performance may be improved. |
