| 摘要 |
PROBLEM TO BE SOLVED: To improve heat transfer performance of transmission of a condensation and boiling heat and to perform high-precise and easy machining. SOLUTION: A heat transfer pipe 100 is formed in such a manner that a plurality of fins 2 are spirally and continuously formed on an inner surface and a spiral groove 1 is formed between the adjoining fins 2 and 2. Each fin 2 comprises an upper region 2U formed approximately in an uneven surface shape or a wave-form shape in the profile of cross section paralleling an inner surface 4 of the heat transfer pipe 100, and a lower region 2L formed approximately in a linear shape in the profile of cross section paralleling the inner surface 4 of the heat transfer pipe 100. Further, in the upper region 2U, a ratio of a curvature of radius R1 of the uneven surface shape in cross section paralleling the inner surface 4 of the heat transfer pipe 100 to a curvature of radius R2 in a protrusion shape in cross section orthogonal to the inner surface 4 is R1≈R2 .
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