HEAT EXCHANGER TUBE FOR CONDENSING STEAM AND MANUFACTURE THEREOF

摘要

PURPOSE: To obtain a metallic heat exchanging tube having ribs each extending annularly or helically on the outer surface and provided with a protruding edge in which heat transfer effect is enhanced by making depressions isolated from each other in a rib flank thereby avoiding restriction of condensate. CONSTITUTION: In a heat exchanger tube 1 for condensing vapor having ribs 2 extending helically on the outer surface with a groove 3 being made between ribs, a large number of depressions 5 spaced apart in the longitudinal direction are made in the rib flank 4 at a pace of 4-30 depressions per 1 cm of the rib length. The depressions are made at a depth equal to 20-80% of the rib height H. The tube 1 with rib is made using an apparatus comprising a tool holder incorporating at least one rear stage rolling disc provided with a rolling tool and a pattern and the depression 5 is formed by making a large number of teeth of the rolling disc to bite into the rib flank 4.