| 摘要 |
PROBLEM TO BE SOLVED: To provide an inner helically grooved heat exchanger tube in which deformation of fins, e.g. collapse or tilting, can be suppressed effectively at the time of enlarging the tube mechanically. SOLUTION: A large number of grooves 12 are made in the inner surface of a tube to extend at a specified lead angle with respect to the circumferential direction of the tube or the tube axis and inner surface fins 14 of a specified height are formed between the grooves 12 thus producing an inner helically grooved heat exchanger tube. Outside diameter of the tube is set at 4-10 mm, depth of the groove is set at 0.10-0.30 mm and the tube wall thickness, i.e., the bottom thickness (t), is set to satisfy a relation; t<=0.1248×D0.32782 (where, D represents the outside diameter of tube).
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