| 摘要 |
PROBLEM TO BE SOLVED: To improve the condensation heat transfer coefficient by forming a continuous fin of a prescribed height with a prescribed angle relative to the axial direction on an inner surface of a pipe, and forming a continuous fin higher than the prescribed height between the fins of the prescribed height. SOLUTION: A continuous spiral fin 12A of a prescribed height with the angleβrelative to the axial direction of a heat transfer pipe 10 for in-pipe condensation is formed on an inner surface of a heat transfer pipe body 11. A continuous spiral fin 12B higher than the prescribed height is formed between the spiral fins 12A of the prescribed height, and a notch 13 is provided in the higher spiral fin 12A. The heat transfer pipe 10 having the continuous and lower spiral fin 12A and the continuous and higher spiral fin 12B is formed. The turbulence effect in the vicinity of a pipe wall is promoted, and the condensation heat transfer coefficient is improved thereby.
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