Heat exchanger tube and methods for producing a heat exchanger tube
A heat exchanger tube with a tube axis, a tube wall, a tube outside and a tube inside. Continuously running, axially parallel or helically circling inner ribs are formed out of the tube wall on the tube inside, each inner rib having two rib flanks and a rib tip. A continuously extending groove is formed between adjacent inner ribs. The rib tip has at regular intervals recurring elevations which have an essentially frustopyramidal form. The inner ribs are raised in the radial direction on the contour line which is defined by the transitional edge of a rib flank to the rib tip and protuberances advancing out of the rib flank are formed in this region. Furthermore, the invention relates to a method for producing a heat exchanger tube.
1. A heat exchanger tube ( 1 ) with a tube axis (A), with a tube wall ( 2 ), with a tube outside ( 21 ) and with a tube inside ( 22 ),
continuously running, axially parallel or helically circling inner ribs ( 3 ) being formed out of the tube wall ( 2 ) on the tube inside ( 22 ),
each inner rib ( 3 ) having two rib flanks ( 31 ) and a rib tip ( 32 ),
a continuously extending groove ( 33 ) being formed in each case between adjacent inner ribs ( 3 ),
the rib tip ( 32 ) having recurring elevations ( 34 ) at regular intervals, and
the elevations ( 34 ) having an essentially frustopyramidal form,
characterized in that the rib flanks ( 31 ) of the inner ribs ( 3 ) are raised in the radial direction on the contour line which is defined by the transitional edge of a rib flank ( 31 ) to the rib tip ( 32 ), in that protuberances ( 37 ) advancing out of the rib flank ( 31 ) in the radial direction are formed in this region and said protuberances ( 37 ) have side surfaces that are coplanar with a surface of the rib flank ( 31 ).
2. A heat exchanger tube ( 1 ) according to claim 1 , characterized in that at least one of the flanks ( 36 ) of a frustopyramidal elevation ( 34 ) is of concave form.
3. The heat exchanger tube ( 1 ) according to claim 1 , characterized in that the frustopyramidal elevations ( 34 ) project above the depression ( 35 ), lying between two elevations ( 34 ), by 20% to 100% of the height of the inner ribs ( 3 ) at the location of the depression ( 35 ).
4. The heat exchanger tube ( 1 ) according to claim 1 , characterized in that a flank angle of the elevations ( 34 ) is no more than 120°.
5. The heat exchanger tube ( 1 ) according to claim 1 , characterized in that an outer structure ( 4 ) is formed on the tube outside ( 21 ).
6. The heat exchanger tube ( 1 ) according to claim 1 , characterized in that the outer structure ( 4 ) is designed in the form of integral, spirally circling outer ribs.