Furukawa Metals Co., Ltd.

Fukurawa Metals Co., Ltd.

Jun Fujikake

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.

Method of producing heat transfer tube for use in boiling type heat

A heat transfer tube for condensation easily obtainable through an additional machining process applied to a low fin tube and a method for manufacturing the same. There is formed a toothed wheel-like part having mountain and valley parts alternately and continuously arranged on the outer circumferential fin part of the low fin tube. Each of the mountain parts is formed into a pyramid-like shape having a transverse cross section of approximately a long snare hand drum-like shape in which longer sides are disposed along grooves provided between the fins of the tube and are arranged to be concave curvatures each resembling an arc. The two slanting faces of the mountain part including these longer sides of the pyramid-like shape gradually and smoothly slant from the top of the pyramid to the bottom thereof. The heat transfer tube for condensation is manufactured by carrying out a transforming process applied to the outer circumference of fins of a low fin tube in the longitudinal direction of the fin tube.

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Yamatokooriyama, Japan

Jun Fujikake