Heat transfer tube for use in boiling type heat exchangers and method of

Abstract

The invention is concerned with a heat transfer tube for use in boiling type heat exchangers, having an excellent heat transfer performance. More specifically, the invention relates to a surface condition of the heat transfer tube for improving the heat transfer performance and a method of producing the tube easily, especially a method for processing the surface condition efficiently and advantageously from an industrial point of view. The essential feature of the invention resides in a provision of a surface condition for promoting the boiling which consists of annular or spiral cavities extending along the tube surface in the circumferential direction of the latter, as well as narrow gaps extending along the cavities so as to allow the cavities to communicate the outside space. If necessary, spiral or annular fins may be provided on the tube surface, so as to improve the boiling performance at the outside of the tube. Further, as a mechanism for promoting the boiling also in the axial direction of the tube, as well as in the circumferential direction, axially extending cavities and narrow gaps extending along the axially extending cavities for communication of the latter with the outside space may be formed on the tube surface, so as to remarkably improve the boiling performance at the outside of the tube.