heat transfer tube

Abstract

Provided is a heat transmission tube wherein the heat transfer rate within a tube can be improved while the increase of a pressure loss is suppressed. A heat transmission tube (11) having an outer diameter of less than 7 mm has an inner surface (10) on which a helical fin (12) that is oriented at a predetermined angle (ß1) with respect to a tube axis direction (D1) and has a height (Hf) of 0.1 to 0.30 mm is formed. In the heat transmission tube (11), the fin (12) is comprised of fin components (12A) divided by a subsidiary helical groove (14) having a depth (Hn) of 0.1 to 0.30 mm. Each fin component (12A) is provided with a protrusion piece (16) on at least the downstream side (D2d) in the helical direction. The protrusion piece (16) is projected at an angle (a) of 5°=a<70° with respect to the fin (12) between the adjacent portions of the fin (12) on the upstream side (D1u) in the tube axis direction. The fin components (12A) are formed so that the distance (Pf) between the fin components (12A) in the fin forming direction is 1.5 mm or more, and the ratio (W1 / W2) of the length (W1) of the protrusion piece (16) to the distance (W2) between the protrusion pieces (16) is 0.3 to 0.9.

Description

technical field [0001] The present invention relates to a heat transfer tube used in heat exchangers such as refrigerators, air conditioners and the like. Background technique [0002] The heat transfer tubes generally used in air conditioners and refrigerators are used to evaporate or condense the refrigerant in the tubes and exchange heat with the fluid flowing outside the tubes. From the perspective of high efficiency and energy saving of heat exchangers, Often use inner surface ditch pay pipe (inside ditch pay pipe). [0003] The inner surface groove sub-pipe has fine triangular or trapezoidal cross-sectional grooves formed linearly or helically with respect to the pipe axis on the inner surface of the pipe. By providing these grooves on the inner surface of the tube, the heat transfer area can be increased compared to a smooth tube, and the heat transfer performance can be improved by the agitation action of the agitated refrigerant liquid. [0004] In recent years, e...

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Problems solved by technology

[0010] However, in the heat transfer tube in Patent Document 1, although the ridges (3a) and (3b) provided by the three-dimensional protrusion (3) can realize stirring of the refrigerant near the inner peripheral surface of the tube, there is no stirring in the radial direction of the tube. Refrigerant flowing in the center side, as a result, the transfer performance that satisfies the above requirements cannot be obtained

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