To provide a heat transfer pipe of absorbing device in which a large amount of staying absorbing liquid stagnating at a groove section in a pipe surface is found and an absorbing performance is remarkably improved in such a way that the stayed absorbing liquid may be spread and widened in thin form at the pipe surface.
The number of N (N is a natural number) of grooves 1 having a length of L1, a width of W1 and a depth of H are properly spaced apart in a pipe circumferential direction at an outer surface of a metallic pipe having a pipe outer diameter D. A plurality of groups of grooves arranged in a circumferential direction are formed in a pipe axial direction. Adjoining groups of grooves are displaced from each other with the positions of the grooves in the circumferential direction. The grooves 1 may satisfy relations of 70 mm≤L1≤130 mm and 0.23 mm≤H<0.5 mm and a pitch P (=πD/N) along the pipe outer circumference of the groove in a circumferential direction is about 6.2 to 8.7 mm. In addition, when a width of a protrusion at the outer surface of a metallic pipe formed between each of the grooves 1 in a circumferential direction of the pipe is W2, it may satisfy a relation of 0.5≤W1/W2≤2.5. Further, the groups of the grooves adjoining in the axial direction of the pipe have ends portions entered from each other and then the length L2 at the assembled sections of the groups of grooves may satisfy a relation of 0≤L2/W1≤1.2.
ISHIKAWA MAMORU
SAEKI CHIKARA
KIJIMA HIROYUKI
