Abstract: The invention relates to a method for the manufacture of tubes bent in a U-shape (hairpin tubes) from a nonferrous metal, immediately following a tube production line. For that purpose, according to the invention, the method for the manufacture of tubes bent in a U-shape from a nonferrous metal, immediately following a tube production line, has the consecutive steps of: a) uncoiling the drawn tube material from a basket winder, b) straightening the drawn tube material, c) annealing and subsequently cooling the drawn tube material before or after cutting, for separation into tube portions, to the starting length for a tube bent in a U-shape, and d) bending the tube portions into a U-shape.

Abstract: The invention relates to a method for the manufacture of tubes bent in a U-shape (hairpin tubes) from a nonferrous metal, immediately following a tube production line. For that purpose, according to the invention a method for the manufacture of tubes bent in a U-shape from a nonferrous metal, immediately following a tube production line, has the consecutive steps of: a) uncoiling the drawn tube material from a basket winder, b) straightening the drawn tube material, c) annealing and subsequently cooling the drawn tube material before or after cutting, for separation into tube portions, to the starting length for a tube bent in a U-shape, d) bending the tube portions into a U-shape. The invention also relates to a production line for the manufacture of tubes bent in a U-shape.

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: 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: The invention relates to heat-exchanger tubes structured on both inner and outer sides with excellent heat-transfer characteristics, which have recesses on the outside and ribs with specific dimensions on the inside. The structuring tools utilized for the various method modifications are adjusted in such a manner that they are not only able to create aligned, continuous grooves and non-aligned, spaced apart recesses but also secondary structures. The heat-exchanger tubes provided preferably with smooth end sections and smooth intermediate sections are utilized in particular in shell and tube heat-exchangers.

Abstract: The invention relates to a heat-transfer tube, in particular an evaporator tube, with fins circumferentially extending on the shellside, which fins are shaped to essentially closed-off channels. The channels are open to the outside through pores with at least two variable sizes. In order to improve the evaporation characteristics, the invention provides advantageous regions for the ratio of the pore sizes and the ratio of the number of pores.

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-transfer tube, in particular an evaporator tube, with fins circumferentially extending on the shellside, which fins are shaped to essentially closed-off channels. The channels are open to the outside through pores with at least two variable sizes. In order to improve the evaporation characteristics, the invention provides advantageous regions for the ratio of the pore sizes and the ratio of the number of pores.

Abstract: The invention relates to heat-exchanger tubes structured on both inner and outer sides with excellent heat-transfer characteristics, which have recesses on the outside and ribs with specific dimensions on the inside. The structuring tools utilized for the various method modifications are adjusted in such a manner that they are not only able to create aligned, continuous grooves and non-aligned, spaced apart recesses but also secondary structures. The heat-exchanger tubes provided preferably with smooth end sections and smooth intermediate sections are utilized in particular in shell and tube heat-exchangers.

Abstract: A process for producing a heat exchanger tube (1) with a highly porous surface structure, in particular for evaporating liquids from pure substances or mixtures on the outside of the tube. The process starts from a rolling operation, by means of which helical fins (2) are produced on the outside of the tube, which fins, in turn, are deformed in a plurality of compression steps by means of gearwheel-like compression wheels (6, 7) in such a manner that the projections (12a, 12b) formed in each case form a cover (3a) for the passages (3) which are situated between the fins (2). The high level of porosity is achieved as a result of the remaining pores (13) and/or slots (14).

Abstract: A metallic finned tube having multiple fins integrally formed on and extending helically on an outside of the tube. The fins number at least four and begin at fin run start locations spaced evenly about a circumference of the tube, with at least one group of side-by-side helical fins being formed which begin at substantially the same circumferential fin run start location on the tube exterior.

Abstract: The invention relates to a metallic heat-exchanger tube (1) with fins (2) which annularly or helically extend or rather extend in axial direction on the outside of the tube for condensing of vapor from pure substances or mixtures on the outside of the tube. To improve the condensation performance by effecting a thinning of a liquid film, the invention includes a making of the fins so that they have a constant fin height H throughout, with the fin flanks (4) being structured by spaced-apart depressions.

Abstract: A metallic finned tube, in particular for heat exchangers, which includes multiple integral fins helically extending on the outside, with the n fin run starts starting at the start of the tube and are evenly distributed around the tube periphery. The finned tube has a number of fin run starts n.gtoreq.4 with at least one group having at least two side-by-side oriented fin run starts (A.sub.1, A.sub.2 or rather A.sub.3, A.sub.4 . . . ).

Abstract: A heat exchanger wall for the transfer of heat from one first medium on one side of the wall to a second medium to be evaporated on the other side of the wall, with this other side having integral, aligned distributor grooves for distributing the liquid phase of the second medium. Good distribution of the liquid on the surface of the heat exchanger wall and simultaneous good vaporization characteristics are guaranteed according to the invention by the following characteristics:a) the distributor grooves cross channels having a pitch t, which channels lie below the distributor grooves,b) the distributor grooves are formed by laterally displaced material of the channel walls, with the depth T of the distributor grooves lying approximately between 30% and 90% of the channel height h, andc) the distributor grooves are connected to the channels through flared segments and/or openings in the distributor grooves.