| 摘要 |
PROBLEM TO BE SOLVED: To provide an inner helically-grooved heat transfer pipe with excellent workability while keeping sufficient performance of evaporating/heat-transferring CO<SB>2</SB>even if the diameter is enlarged. SOLUTION: A pipe outer diameter D is larger than 7 mm and not more than 13 mm, height H of a fin is 0.1-0.4 mm, a lead angleβof the fin is 0-35 degrees, a ratio (H/D) of the fin height H and the pipe outer diameter D is 0.01-0.05, the number N of grooves is 40-100, and an apex angleθof a slant face of the groove is 10-40 degrees. When a tensile strength of a pipe material isσB [N/mm<SP>2</SP>], a root radius of the fin is R [mm], and a bottom thickness is t[mm], a parameterαobtained by multiplying the ratio (H/D) by the bottom thickness t (α=(H/D)×t) is 0.04 or less, a parameterγobtained by multiplying a ratio(H/R) of the fin height H and the fin root radius R by the bottom thickness t (γ=(H/R)×t) is 0.5-4.0, and the bottom thickness t is not less than 25.5×D/[2×(0.8×σB+25.5)]. COPYRIGHT: (C)2011,JPO&INPIT |
