| 摘要 |
PROBLEM TO BE SOLVED: To provide a falling liquid film-type refrigerating machine of light weight, capable of effectively reducing pressure drop inside of a tube without degrading effect of improvement of heat transfer performance by a groove formed on an outer face of the tube and a fin. SOLUTION: This heat transfer tube 10 is formed in a state that the fin 12 formed on the outer face of the tube has a fin height (H) of 0.15-0.35 mm, a fin pitch (P<SB>1</SB>) of 0.9-2.4 mm, a minimum width (W) of a fin top portion of 0.3-0.7 mm, a bottom thickness (t) of the tube of 0.40-0.55 mm, and a radius of curvature (R) of a fin base of 0.05-0.3 mm, the groove 14 has a groove depth (D) of 0.1-0.3 mm and a groove pitch (P<SB>2</SB>) of 0.5-1.0 mm, the fin and the groove are formed in the tube axial direction while satisfying that a ratio (d<SB>1</SB>/H) of the difference (d<SB>1</SB>) between the fin height and the groove depth and the fin height (H) is 0.05-0.25, and a depth (d<SB>2</SB>) of hollows 16 formed on an inner face of the tube is 0.03 mm or less. COPYRIGHT: (C)2009,JPO&INPIT
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