The invention relates to a heat exchanger tube produced by bending a metal strip (11), characterized in that said strip (11) has a thickness that can vary between at least one first thickness (e.sub.1) and at least one second thickness (e.sub.2) greater than said first thickness (e.sub.1), and in that said tube has thinned first zones (Z1) and reinforced second zones (Z2) located at the points of greatest mechanical stress, said first zones (Z1) being formed by first portions (P1) of said strip of first thickness (e.sub.1) and said reinforced second zones (Z2) being formed by second portions (P2) of said strip (11) of second thickness (e.sub.2). The invention also relates to a heat exchanger comprising a core bundle of such tubes, and to a method of obtaining such a tube.

The invention relates to a heat exchanger tube produced by bending a metal strip (11), characterized in that said strip (11) has a thickness that can vary between at least one first thickness (e.sub.1) and at least one second thickness (e.sub.2) greater than said first thickness (e.sub.1), and in that said tube has thinned first zones (Z1) and reinforced second zones (Z2) located at the points of greatest mechanical stress, said first zones (Z1) being formed by first portions (P1) of said strip of first thickness (e.sub.1) and said reinforced second zones (Z2) being formed by second portions (P2) of said strip (11) of second thickness (e.sub.2). The invention also relates to a heat exchanger comprising a core bundle of such tubes, and to a method of obtaining such a tube.

Fluid circulation tube and heat exchanger equipped with tubes of this type are disclosed. The tube (6) is produced by bending, and, once its wall has been bent, has a base portion (12) prolonged laterally by two linking portions (13) leading to two top portions (14) turned toward one another, which terminate in end legs (15) turned toward the base portion (12), forming at least two parallel longitudinal internal channels (16) into which the two systems (20) of bends (21) of a corrugated disrupter (17) can be inserted, these systems being interconnected by a central part (23) inserted into a gap left between said legs and the base portion.

Fluid circulation tube and heat exchanger equipped with tubes of this type are disclosed. The tube (6) is produced by bending, and, once its wall has been bent, has a base portion (12) prolonged laterally by two linking portions (13) leading to two top portions (14) turned toward one another, which terminate in end legs (15) turned toward the base portion (12), forming at least two parallel longitudinal internal channels (16) into which the two systems (20) of bends (21) of a corrugated disrupter (17) can be inserted, these systems being interconnected by a central part (23) inserted into a gap left between said legs and the base portion.

A method in accordance with the present application includes sending a raw tube from a drum to an unwinding side capstan while the raw tube is rotated around a central axis perpendicular to a winding shaft of the drum by rotating the drum and the unwinding side capstan about the central axis concurrently with unwinding of the raw tube from the drum holding the raw tube, on an inner surface of which multiple straight grooves along a longitudinal direction of the raw tube are formed with an interval in a circumferential direction, in a coil shape, to wind the raw tube around the unwinding side capstan, and drawing in which the unwound raw tube is drawn while the diameter of the raw tube is reduced, and then the raw tube is wound around the drawing side capstan to twist the raw tube and obtain an inner spiral grooved tube.

A method in accordance with the present application includes sending a raw tube from a drum to an unwinding side capstan while the raw tube is rotated around a central axis perpendicular to a winding shaft of the drum by rotating the drum and the unwinding side capstan about the central axis concurrently with unwinding of the raw tube from the drum holding the raw tube, on an inner surface of which multiple straight grooves along a longitudinal direction of the raw tube are formed with an interval in a circumferential direction, in a coil shape, to wind the raw tube around the unwinding side capstan, and drawing in which the unwound raw tube is drawn while the diameter of the raw tube is reduced, and then the raw tube is wound around the drawing side capstan to twist the raw tube and obtain an inner spiral grooved tube.

The present invention relates to an absorption chiller which comprises an evaporator, an absorber, a regenerator and a condenser and has an absorbing solution and a refrigerant circulating. A heat transfer pipe, which is provided on one or more of the evaporator, absorber, regenerator and condenser, is comprised, and a ductile stainless steel pipe, which has 1% or less of delta ferrite matrix structure on the basis of the grain size area, is applied to the heat-transfer pipe. Therefore, copper-level flexibility can be obtained in comparison with an existing stainless steel pipe.

Apparatus and methods for additively manufacturing microtube heat exchangers are disclosed herein. A heat exchanger header is additively manufactured with high density microtube arrays to achieve an integrated structure achieving values of heat transfer effectiveness E.sub.ff up to ninety percent and values of transfer surface area densities up to 20,000 m.sup.2/m.sup.3. The heat exchanger header can be printed with a high density microtube array to separate different types of fluids or liquids into different microtubes and to form a high quality seal. Additionally, microtubes and/or microtube arrays can be additively manufactured to be curved or to have pleats; and microtube lattice arrays can be compactly positioned within hollow support structures.

Apparatus and methods for additively manufacturing microtube heat exchangers are disclosed herein. A heat exchanger header is additively manufactured with high density microtube arrays to achieve an integrated structure achieving values of heat transfer effectiveness E.sub.ff up to ninety percent and values of transfer surface area densities up to 20,000 m.sup.2/m.sup.3. The heat exchanger header can be printed with a high density microtube array to separate different types of fluids or liquids into different microtubes and to form a high quality seal. Additionally, microtubes and/or microtube arrays can be additively manufactured to be curved or to have pleats; and microtube lattice arrays can be compactly positioned within hollow support structures.

A metal bend pipe having a bend portion bent in a semi-circular arc shape is provided, in which an identification part that enables one of the two end portions of the bend portion to be identified as the bending-start side or the bending-end side is provided, and the identification part is integrally formed as a protruding and/or recessed three-dimensional region. Thus, it is possible to easily and reliably identify which of the two end portions of the bend portion is the bending-start side or the bending-end side.