Heat exchanger tube and method for producing it

A heat exchanger tube with a tube axis and with a tube wall having a tube outside and a tube inside, axially parallel or helically encircling inner ribs, with a groove which lies in each case between adjacent inner ribs, being formed from the tube wall on the tube inside, characterized

• in that a helix angle, measured with respect to the tube axis, of the inner ribs is smaller than or equal to 45°,
• a region of each of the inner ribs which is remote from the tube wall is deformed at regular intervals asymmetrically on only one side essentially in the tube circumferential direction, the deformed material of the inner ribs forming protrusions above the groove,
• the protrusions extend in each case over a finite deformation zone along an inner rib,
• the markedness of the deformation changes continuously within the deformation zone, the deformation being marked to a greater extent in the middle of the deformation zone than at the margins,
• cavities which assist the formation of bubbles are located between the groove bottom, the sides of the inner ribs and the protrusions formed, and
• in the middle of the deformation zone, the deformed material of an inner rib touches the circumferentially adjacent inner rib and the groove bottom between the inner ribs and a circumferentially adjacent inner rib, with the result that the groove is partially closed between adjacent inner ribs.