Abstract: A metallic heat exchanger tube has fins which run helically around the outside of the tube, are molded integrally therefrom and are of continuous design and the fin base of which protrudes substantially radially from the tube wall, and with primary grooves located between respectively adjacent fins. At least one undercut secondary groove is arranged in the region of the groove base of the primary grooves. The secondary groove is delimited toward the primary groove by a pair of mutually opposite material projections formed from the material of respectively adjacent fin bases and the cross-section thereof is varied at regular intervals without having an influence on the shape of the fins. There is a spacing between the opposite material projections, the spacing being varied at regular intervals, as a result of which local cavities are formed.

Abstract: The invention relates to a metallic heat exchanger tube with fins which run helically around the outside of the tube, are molded integrally therefrom and are of continuous design and the fin base of which protrudes substantially radially from the tube wall, and with primary grooves located between respectively adjacent fins. At least one undercut secondary groove is arranged in the region of the groove base of the primary grooves. Said secondary groove is delimited toward the primary groove by a pair of mutually opposite material projections formed from material of respectively adjacent fin bases. Said material projections extend continuously along the primary groove. The cross section of the secondary groove is varied at regular intervals without having an influence on the shape of the fins. There is a spacing between the opposite material projections, said spacing being varied at regular intervals, as a result of which local cavities are formed.

Abstract: The invention relates to a heat-exchanger tube structured on both sides with excellent heat transfer characteristics utilizing both outer and also inner fins and secondary grooves intersecting the inner fins. Two spaced-apart rolling tools are provided in the utilized device in order to form the outer fins of two adjacent rolling tools; the inner structure is formed by two differently profiled mandrels. The first mandrel forms in a first forming area the inner fins. The second mandrel forms in a second forming area the inventive secondary grooves into the earlier created inner fins.

Abstract: The invention relates to a heat-exchanger tube structured on both sides with excellent heat transfer characteristics utilizing both outer and also inner fins and secondary grooves intersecting the inner fins. Two spaced-apart rolling tools are provided in the utilized device in order to form the outer fins of two adjacent rolling tools; the inner structure is formed by two differently profiled mandrels. The first mandrel forms in a first forming area the inner fins. The second mandrel forms in a second forming area the inventive secondary grooves into the earlier created inner fins.

Abstract: A metallic heat transfer tube, in particular for the evaporation of liquids from pure substances or mixtures on the outside of the tube. Fins are integrally formed on the outside of the tube. Recesses are arranged in the area of the base of the primary grooves and extend between the fins. The recesses are in the form of re-entrant secondary grooves. The mechanical stability of the tube is not negatively influenced because material is primarily removed from the fin flanks toward the base of the groove so that the re-entrant secondary grooves are radially open.

Abstract: A metallic heat transfer tube, in particular for the evaporation of liquids from pure substances or mixtures on the outside of the tube. Fins are integrally formed on the outside of the tube. Recesses are arranged in the area of the base of the primary grooves and extend between the fins. The recesses are in the form of re-entrant secondary grooves. The mechanical stability of the tube is not negatively influenced because material is primarily removed from the fin flanks toward the base of the groove so that the re-entrant secondary grooves are radially open.

Abstract: The invention relates to a heat-exchanger tube structured on both sides with excellent heat transfer characteristics utilizing both outer and also inner fins and secondary grooves intersecting the inner fins. Two spaced-apart rolling tools are provided in the utilized device in order to form the outer fins of two adjacent rolling tools; the inner structure is formed by two differently profiled mandrels. The first mandrel forms in a first forming area the inner fins. The second mandrel forms in a second forming area the inventive secondary grooves into the earlier created inner fins.

Abstract: A metallic heat transfer tube, in particular for the evaporation of liquids from pure substances or mixtures on the outside of the tube. Fins are integrally formed on the outside of the tube. Recesses are arranged in the area of the base of the primary grooves and extend between the fins. The recesses are in the form of reentrant secondary grooves. The mechanical stability of the tube is not negatively influenced because material is primarily removed from the fin flanks toward the base of the groove so that the re-entrant secondary grooves are radially open.

Abstract: A metallic heat transfer tube, in particular for the evaporation of liquids from pure substances or mixtures on the outside of the tube. Fins are integrally formed on the outside of the tube. Recesses are arranged in the area of the base of the primary grooves and extend between the fins. The recesses are in the form of re-entrant secondary grooves. The mechanical stability of the tube is not negatively influenced because material is primarily removed from the fin flanks toward the base of the groove so that the re-entrant secondary grooves are radially open.