HEAT TRANSFER PIPE WITH INNER SURFACE GROOVE

摘要

PROBLEM TO BE SOLVED: To improve a heat transferring efficiency with helical fins by a method wherein an inclination angle of a fin in respect to an axis of a heat transfer pipe is set in a specified range in an odd-numbered region counted from one region and an inclination angle of the fin in respect to an axis of the heat transfer pipe is set in a specified range in an even-numbered region counted from the one region. SOLUTION: Many fins 2 extending continuously in a zig-zag form toward a circumferential direction are formed in parallel to each other at an inner circumferential surface of a heat transfer pipe 1 having some inner grooves. The inner circumferential surface of the heat transfer pipe 1 is divided into regions R1 to R4 in a circumferential direction. At a region of odd-number counted from any one region of the regions R1 to R4, an inclination angleαof the fin 2 in respect to an axis of the heat transfer pipe 1 is set to be 10 to 25 deg. and in turn, at a region of even number counted from one region, an inclination angleβof the fin in respect to an axis of the heat transfer pipe 1 is set to be -10 to -25 deg.. With such an arrangement as above, it is possible to improve a heat transfer rate through the fins 2.