Patent ID: 6488078
Filing Date: 2002-12-03
Classification: B21C,F28F,Y10T

Abstract:
A heat-exchanger tube with smooth end sections and at least one structured section between the end sections, whereby an outside diameter of the structured section is no greater than an outside diameter of the smooth end sections, the structural section having the following characteristics:a) spaced-apart recesses having an essentially trapezoidal cross section with a length L of a maximum of 10% of the circumference of the tube inclined on the outside of the tube at a pitch angle with respect to the tube axis; b) the pitch P of the recesses being from 0.25 mm to 2.2 mm, measured perpendicularly with respect to their plane of symmetry; c) the width W of the recesses being W=0.6 P to 0.8 P, measured at half the depth T of the recesses; d) the flank angle &dgr; of the recesses being &dgr;=7Â° to 25Â°, measured relative to their plane of symmetry; and e) inner ribs with a height H from 0.15 mm to 0.60 mm extending helically on the inside of the tube at a helix angle E from 10Â° to 50Â°, measured relative to the tube axis.