INTERNALLY-GROOVED HEAT TRANSFER PIPE FOR EVAPORATOR

摘要

PROBLEM TO BE SOLVED: To provide an internally-grooved heat transfer pipe suppressing accumulation of a refrigerating machine oil, having sufficient CO₂ evaporation heat-transferring performance, being advantageous in fin molding performance by reducing a diameter, and suppressing fin collapse and fin falling in expanding a heat transferring tube.;SOLUTION: A pipe outer diameter D is 2-4 mm, a height H of the fin is 0.05-0.25 mm, a lead angle β of the fin is 0-35°, a ratio (H/D) of the fin height H and the pipe outer diameter D is 0.025 or more, the number N of grooves is 20-60, and an apex angle θ of a slant face of the groove is 12-40°. When a tensile strength of a pipe material is σB[N/mm²], a root radius of the fin is R[mm], and a bottom thickness is t[mm], α=(H/D)×t is 0.015 or less, γ=(H/R)×t is 0.2-2.0, and t is t≥25.5×D/[2×(0.8×σB+25.5)].;COPYRIGHT: (C)2010,JPO&INPIT