Heat-transfer tubes with grooved inner surface.

摘要

A heat-transfer tube having spiral grooves on its inner surface, wherein the ratio of the depth of said grooves to the inside diameter of the tube is between 0.02 and 0.03, the helix angle of said grooves to an axis of the tube is between 7° and 30°, the ratio of the cross-sectional area of respective grooved section to said groove depth is between 0.15 and 0 0.40 the apex angle in cross section of a ridge located between said respective grooves is between 30° and 60° whereby the grooved inner surface is adapted to phase-transition fluid flowing.