| 摘要 |
PROBLEM TO BE SOLVED: To provide an inside surface grooved pipe suitable for a heat transfer pipe of a heat exchanger using a non-azetropic mixed refrigerant, and superior in repetitive internal pressure fatigue characteristic. SOLUTION: A spirally extended groove 5 is formed on an inside surface of the inside surface grooved pipe 4 composed of copper or a copper alloy. A part between the grooves 5 is formed as a fin 6. When a lead angle of the groove 5 is set to a (°), and the bottom thickness is set to b (mm), a and b satisfy the following numerical expression: b≥1.04/a+0.20. When a radius of curvature of a root part 6a of the fin 6 is set to r, and a groove bottom width of the groove in a pipe axis orthogonal cross section is set to W, the ratio (r/W) is set to 0.280 or more. COPYRIGHT: (C)2004,JPO
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