EP0770845A2 - Heat exchanger tube with vortex generating turbulating means - Google Patents

Abstract

The characteristic features of a tube for use in tubular-bundle heat exchangers are that: (i) the inner wall of the tube (1) is free of projections of depressions affecting fluid flow; (ii) a tubular- or rod-shaped turbulence- producing string (4) is present in the tube (1), the outer surface of the string (4) being provided with (a) flow-transverse windings (6), (b) flow-transverse structures (12,12') or (c) burls (13) or prongs; and (iii) the string (4) is distanced from the inner surface (18) of the tube (1), except at point contacts, such that there is space left for fluid flows. Also claimed is an embodiment in which a U-shaped string (4) runs through a pair of side-by-side tubes.

Description

The invention relates to a tube for tube bundles of heat exchangers with elements located inside the tube and generating turbulence in the flow in the tube.

It is known to improve the heat transfer between fluids and these bounding walls by increasing the flow velocity or by creating turbulence in the flow. Such turbulence is achieved through vortex-generating current disturbance elements. Known pipes of this type in principle have profiles on the inside of the pipe in the sense of corrugations, projections, ribs or the like.

The arrangement of vortex generating current disturbance elements on the inner surface of the tubes becomes problematic when the single tube of the heat exchanger is made of a material whose wall cannot be deformed in the conventional way. This applies in particular to pipes that have to be manufactured using the extrusion process. For this purpose, DE-OS 35 21 914 discloses arranging webs in the individual tube which do not completely penetrate the tube and are shaped in a wave shape. Such a shape is only conceivable in the extrusion process for light metal, in particular aluminum, where it is possible to produce such corrugated webs by suitable design of the recipient.

However, this known method cannot be used where the material of the tube cannot be deformed in the known manner during extrusion or another method. This is particularly the case with pipes made of metallic materials such as titanium, high-alloy Steels, nickel-based alloys or pipes made of silicon carbide and graphite. Heat exchangers with graphite tubes are preferred for heat exchange between liquids, vapors or gases, which require a chemically resistant tube material.

The invention has for its object to design tubes for use in the tube bundles of tube bundle heat exchangers in such a way that they have vortex-generating elements and / or flow rate-increasing elements which disturb the fluid flow, without the ductility of the tube material being important. In particular, the invention is intended to provide access to pipes made of materials which are difficult to deform, in particular pipes made of graphite, which have improved heat transfer performance.

The object is achieved in accordance with the characterizing part of claim 1 in that the inner wall of the tube is free from elevations and depressions influencing the fluid flow in the tube and in the interior of the tube there is a tubular or rod-shaped strand, the outer surface of which is in the form a) a thread lying essentially transversely to the direction of flow in the tube or b) has shafts arranged in the same way or c) is studded or studded so that the strand, with the exception of a linear contact with the inner surface of the heat exchanger tube at a distance of this inner surface is positioned so that there is a space between the strand and the inner surface of the heat exchanger tube for the fluid to flow through the heat exchanger tube.

A solution to the problem, which is limited to tubes of tube bundle heat exchangers lying side by side in pairs, is given in claim 2. This claim is characterized in that the inner wall of the tubes is free from elevations and depressions influencing the fluid flow in the tubes, that there is a tubular or rod-shaped strand in the interior of the tubes, the outer surface of which is in the shape a) of a substantially transverse to Flow direction in the thread lying in the tubes or b) has shafts arranged in the same way or c) is studded or spiked so that the strand is positioned apart from these inner surfaces with the exception of at most linear contact with the inner surfaces of the heat exchanger tubes, so that between the strand and the inner surface of the heat exchanger tubes there is a space for the fluid to flow through the heat exchanger tubes, that the strand has a U-shape, that the legs of the U of the strand are located in two adjacent tubes of a heat exchanger, and the connecting the thighs e bend of the U is arranged outside the tubes.

The subordinate claims represent refinements of the invention and applications of the solution according to the invention. They are hereby introduced into the descriptive part.

Through the measures according to claims 1 and 2, turbulence is generated in the flow passing through the pipe with the simplest of means. At the same time, the flow velocity in the pipe can be increased. Both measures, the generation of turbulence and the increase in the flow velocity in the pipes each lead to an improvement in the heat transfer performance of the pipes. Do both measures at the same time applied, the heat transfer performance is correspondingly higher. To achieve the effects described, only a suitably profiled strand has to be inserted into the tube. Since this measure is not linked to the pipe production, heat exchanger pipes can be equipped with the strands according to the invention at any time in their operational existence. Both new systems and systems that have already been in operation can be equipped with it. The latter option is particularly advantageous for adapting existing heat exchangers to changing operating conditions. But even when designing new systems, the designer is often confronted with constraints, the circumvention of which he can use the invention in an advantageous manner. If, for example, for spatial reasons, it is bound to a specific heat exchange surface with which the required or required exchange service cannot be provided with normal pipes, it can now fall back on the solution according to the invention and increase the performance in a simple manner. If required, the performance can be reduced at a later point in time by removing all or part of the strands and adapted to other circumstances. From this example it can be easily deduced that the dimensions of heat exchangers can be reduced by keeping the heat exchange capacity constant in comparison with conventional heat exchangers by using the means of the invention to achieve a reduction in the length of the pipes used or to reduce the length of the pipes used Reduction of their number is used in the heat exchanger. In the former case, the exchanger becomes shorter, in the other, slimmer. In some cases, the process engineering design means that pipes with very small inner diameters are required. Such pipes are out Production-technical reasons and / or because of their high sensitivity to breakage, if they consist of silicon carbide or carbon or graphite, for example, cannot be produced with economically viable effort. The invention now makes it possible to advance into the field of the use of such pipes which are difficult to manufacture and which are practically unusable by using larger, mechanically more stable pipes which can be produced at a reasonable cost and which are thus modified by using strands according to the invention that they fully correspond to the technical scope of the smaller pipes.

The invention is applicable to all types of tubes for heat exchangers which allow the introduction of strands according to the invention.

However, the invention is of particular importance for those heat exchangers through which liquid, gaseous or vapor-like materials have to be passed, which presuppose chemically resistant material for the pipes. Tubes made of special, difficult-to-process metallic materials such as titanium, titanium-palladium alloys, high-alloy steels or nickel-based alloys or of ceramic such as silicon carbide and in particular of graphite are suitable for such heat exchangers. A special feature of these materials and here especially of graphite is that they cannot be provided with vortex-generating current disturbance elements in the extrusion manufacturing process. Rather, pipes made of these materials are essentially smooth pipes on the inside. If the strands according to the invention, which have profiles of the outer circumference, are used in such pipes, the advantage of the resistant material becomes with the improvement of the heat transfer performance combined.

The profiles with which the strands inserted into the pipes are provided can take a variety of forms. They only have to cause laminar flows to be converted into turbulent and slightly turbulent flows into more turbulent flows. The following surface configurations of the strands are given as examples: various thread-like shapes, ribs, knobs, spikes and, as a preferred shape, waves.

The strands can be hollow on the inside or made of solid material. If hollow strands are used, they are preferably closed on at least one side in order to prevent the formation of a second flow line in the tube and to avoid the accumulation or retention of fluid from the heat exchanger in the strand. Where this makes sense, both ends of the hollow strand can also be closed. However, if this has advantages, it is also possible to leave the ends open. Commercially available, relatively inexpensive corrugated pipes are preferably used as hollow strands. The hollow strands can either be partially or completely filled with a suitable material. For example, the part of the strand pointing downward in the heat exchanger may contain only a filling that weighs down, in order to tighten the hanging strand and to prevent excessive back and forth movements, or the interior of the strand is completely foamed with a specifically light material around the strand to give good longitudinal stability with overall low weight.

A particularly preferred solution to the problem consists of U-shaped strands, for example in a U-shape to use curved corrugated pipes. The legs of such a U-shaped strand are inserted into two adjacent tubes of the heat exchanger and the part connecting the legs naturally remains outside the exchanger tubes. Here, the ends can also not be closed if the U-shaped strands are arranged in such a way that their openings point in the direction of gravity, so that any process medium that has entered the interior of the strands can flow out again. In this way, a heat exchanger can be equipped with the strands according to the invention with the simplest of means and with little effort.

The strands are fastened in the heat exchanger tubes using simple means known per se, such as suspensions or webs attached to the tube ends or pins guided through the strand ends, which are supported on the tube ends.

In order to facilitate the inflow of the respective fluids exchanging heat in the heat exchangers into the heat exchanger tubes equipped with the strands according to the invention, according to another advantageous variant, the heat exchanger tubes or the flow channels aligned with the tube ends of these tubes in the upper and lower tube plates of the tube bundle, in which these pipes are installed, have conical or wedge-shaped extensions at the inflow end. This measure is particularly recommended when using U-shaped strands on the side of the U-shaped connection of the legs. But it is not a condition. Where this seems advantageous, such extensions can also be fitted on the outflow side of the tube bundle.

The material from which the strands according to the invention are made depends on the conditions of use, especially on the medium to which the strands are exposed and on the intended operating temperature. The specialist selects the most suitable material based on his knowledge. Some, without limitation, some of the materials in question are mentioned as examples: metal, plastic, rubber, wood, ceramic, carbon. Of the plastics, polypropylene (PP) or polyvinyl chloride (PVC) are preferably used for media that are less aggressive. In more aggressive media and at higher application temperatures, strands of fluorine-containing polymers such as polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), tetrafluoroethylene-perfluoropropylene copolymer (FEP) or copolymers of tetrafluoroethylene with perfluoroalkyl vinyl ether (PFA) are preferably used. The range of carbon materials is not limited to non-graphitic and graphitized carbon. Parts made from carbon fiber reinforced carbon or from plastic reinforced with carbon fibers can also be used.

The outer diameter of the strand is preferably one third to eight tenths of the inner diameter of the heat exchanger tube surrounding it. These proportions have proven themselves in heat exchangers for aggressive chemical media in which the exchanger tubes are made of graphite and the strands are made of plastic. However, the invention is not limited to these dimensions. You can deviate from this if necessary.

For cases in which the strand must be arranged in a stable position within the tube, it is recommended that Support the strand in places on the smooth inner wall of the pipe. In general, this can be achieved in that the strand is supported on the inner wall of the exchanger tube using known means, such as webs. When choosing and arranging the support elements, care should only be taken that the flow in the annular gap is not significantly impaired. According to a preferred procedure, support is achieved when the strand passes through the tube in a spiral shape. This spiral shape is created with flexible material by twisting the strand, which is designed as a corrugated tube, for example, when inserted into the tube, or locking it after insertion at the opposite end of the tube or tube plate, then twisting it, compressing it a little, and twisting it then also at the other end of the tube or tube sheet. In this way, the strand is supported on the inner surface of the tube.

The effectiveness of the invention is demonstrated below by means of an exemplary embodiment:
All heat exchanger tubes of an industrially applicable partial pressure condenser equipped with fluid-tight graphite tubes, 32 mm outer diameter and 22 mm inner diameter were equipped with commercially available corrugated tubes made of polytetrafluoroethylene bent in U-shape according to FIG. on the outer wall of the tube, that is to say at the bottom of the corrugation, the diameter measured was 14 mm. The heat transfer performance of the partial pressure condenser was applied to the same product and with the same coolant (water) once without built-in turbulence-generating strands and once measured with such strands:

• Versuch ohne Stränge in den Rohren,
  Massestrom Produkt: 6066 kg/h
  Temperatur des Produkts am Apparateeingang: 123,75 °C
  Temperatur des Produkts am Apparateausgang: 37,4 °C
  Massestrom Kühlwasser: 147 m³/h
  Temperatur des Kühlwassers am Apparateeingang: 21 °C
  Temperatur des Kühlwassers am Apparateausgang: 26 °C
• Versuch mit Strängen in den Rohren:
  Massestrom Produkt: 11058 kg/h
  Temperatur des Produkts am Apparateeingang: 123,60 °C
  Temperatur des Produkts am Apparateausgang: 39 °C
  Massestrom Kühlwasser: 51 m³/h
  Temperatur des Kühlwassers am Apparateeingang: 20 °C
  Temperatur des Kühlwassers am Apparateausgang: 39 °C

Operating conditions / measurement results:

• Trial with no strands in the tubes,
  Mass flow product: 6066 kg / h
  Temperature of the product at the inlet of the device: 123.75 ° C
  Temperature of the product at the device outlet: 37.4 ° C
  Mass flow cooling water: 147 m ³ / h
  Temperature of the cooling water at the device inlet: 21 ° C
  Temperature of the cooling water at the appliance outlet: 26 ° C
• Experiment with strands in the tubes:
  Mass flow product: 11058 kg / h
  Temperature of the product at the inlet of the device: 123.60 ° C
  Temperature of the product at the device outlet: 39 ° C
  Mass flow cooling water: 51 m ³ / h
  Temperature of the cooling water at the device inlet: 20 ° C
  Temperature of the cooling water at the appliance outlet: 39 ° C

A comparison of the amounts of heat transferred per unit of time in the two tests shows that 1.32 times more heat was transferred in the solution according to the invention than in the apparatus without strands in the heat exchanger tubes. The increase in heat transfer capacity is achieved with a cooling water quantity reduced to approx. 1/3 and an increase in product throughput of almost double.

The following figures further illustrate the invention by means of schematic representations.

Fig. 1:

Einen Teillängsschnitt durch einen Rohrbündelwärmeaustauscher der eine erfindungsgemäße Rohranordnung wiedergibt.

Fig. 2:

Einen Teillängsschnitt durch einen Rohrbündelwärmeaustauscher, mit einem in benachbarte Wärmeaustauscherrohre eingesetzten u-förmigen Strang.

Fig. 3:

Eine Draufsicht auf die Stirnseite einer Kopfplatte des Rohrbündels eines Wärmetauschers, dessen Austauscherrohre mit u-förmig gestalteten Strängen ausgerüstet sind.

Fig. 4:

Einen Teillängsschnitt durch das Rohrbündel eines Wärmetauschers am Ort eines Austauscherrohres mit einem gefüllten Hohlstrang.

Fig. 5:

Die Ausführung eines erfindungsgemäßen Stranges als Wellrohr.

Fig. 6, 6a, 6b, 6c:

Ein Wärmeaustauscherrohr, in dem ein Strang entlang einer wendelförmigen Linie an der Rohrwand anliegt und festgelegt ist.

Show it:

Fig. 1:

A partial longitudinal section through a tube bundle heat exchanger which represents a tube arrangement according to the invention.

Fig. 2:

A partial longitudinal section through a tube bundle heat exchanger, with a U-shaped strand inserted into adjacent heat exchanger tubes.

Fig. 3:

A top view of the end face of a head plate of the tube bundle of a heat exchanger, the exchanger tubes of which are equipped with U-shaped strands.

Fig. 4:

A partial longitudinal section through the tube bundle of a heat exchanger at the location of an exchanger tube with a filled hollow strand.

Fig. 5:

The execution of a strand according to the invention as a corrugated tube.

6, 6a, 6b, 6c:

A heat exchanger tube in which a strand lies and is fixed along a helical line on the tube wall.

In the partial longitudinal section according to FIG. 1, a tube 1 of the tube bundle of a tube bundle heat exchanger is shown, the parts of which in contact with the product, with the exception of the strand inserted into the tubes 1, consist of tantalum.

The surface of the smooth tantalum tube 1 is welded into the upper tube sheet 2 and the lower tube sheet 3 of the tube bundle, which are only hinted at. The strand body 4 is in the form of a tube made of FEP, which is closed at its upper end 5 by squeezing and / or welding, and is provided on its outer surface with a thread-like profile 6. The strand body 4 is open at its lower end 9. The strand body 4, which causes the turbulence and reduces the fluid-accessible inner cross section 7 of the heat exchanger tube 1, is attached to both the upper tube sheet 2 and the lower tube sheet 3 of the tube bundle by means of a pin 8, 8 'guided through the strand 4, which is located on the upper 2 and supports the lower tube sheet 3, held. It is possible to keep the strand 4 under a certain longitudinal tension by means of these detents 8, 8 ', in order to prevent it from moving back and forth which disturbs the flow during operation. FIG. 1 a, which shows a view of the upper part of FIG. 1 rotated by 90 °, makes it clear that the locking of the strand 4 is effected by a pin 8. The fluid passing through the heat exchanger flows, as the arrows in FIGS. 1 and 1a indicate, from bottom to top through the heat exchanger. According to a preferred embodiment, the largest outside diameter a of the strand is 4 1/3 to 8/10 of the inside diameter b of the heat exchanger tube 1.

2 shows a variant of the invention in which the legs 10, 10 'of a U-shaped corrugated tube 11 are located in adjacent tubes 1, 1' of a heat exchanger. The elevations 12 and depressions 12 'on the surface of the strand 4, which cause the turbulence in the flow present in the tubes 1, 1', run in a spiral shape.

The parts of the heat exchanger which come into contact with the product, of which only the upper tube sheet 2 and two tubes 1, 1 'of the tube bundle are shown in sections, consist, with the exception of the extruded bodies 4, of graphite impregnated with a synthetic resin. The graphite tubes 1, 1 'are glued into the upper tube sheet 2 and into the lower tube sheet (not shown) of the tube bundle 16. The threaded tubes forming the extruded bodies 4 consist of polypropylene. In the heat exchanger only partially shown here, as the arrows indicate, the product flow runs from top to bottom through the pipes 1, 1 '. On the inlet side 15, 15 'of the product flow into the pipes 1, 1' there is a cross section 14, 14 ', for example conically widening counter to the direction of flow, in order to facilitate the inflow of the product fluid into the pipes 1, 1'. The figure shows that the strands 4 are always closed in this arrangement in the heat exchanger tubes 1, 1 'on their upper, the inflow side 15, 15' in the exchanger tubes 1, 1 '. No product can enter them. At its lower end, which is not visible here, the strands 4 can either be open or closed. You can also e.g. be fixed to the lower tube plate or not. It is not difficult to see that the U-shaped embodiment also offers considerable advantages during assembly.

In the plan view shown in Fig. 3 on the upper tube sheet 2 of a tube bundle of a heat exchanger according to the invention, in which the tubes 1 are equipped with U-shaped strands 4, the inflow openings 15, 15 'of the heat exchanger tubes 1 and which are each over two adjacent Tubes 1, 1 'extending U-shaped ends of the strands 4 can be seen. The pipe 1 '' is a plugged blind pipe. However, it could also be provided with a corrugated tube 4 according to FIG. 1.

In Fig. 4 the upper 2 and the lower tube sheet 3 of a tube bundle are indicated, in which (2, 3) an exchanger tube 1 is glued (16). The parts of the exchanger in contact with the product, with the exception of the strand body 4, again consist of fluid-tight graphite. The tubular strand body 4, closed at its upper 5 and lower 9 end, consists of a rubber-like copolymer of vinylidene fluoride with hexafluoropropylene, which is commercially available under the ^R Viton brand. Its surface has a plurality of knobs 13 in order to cause the desired turbulence in the flow in the tube 1. The strand body 4 is suspended at its upper end 5 by a welded-in PTFE pin 8 penetrating it at the top of the upper tube sheet 2 of the tube bundle. In its lower part, the strand body 4 contains a specifically heavy mass 17, for example silicon dioxide bonded with a synthetic resin, heavy spar or chips of a corrosion-resistant alloy, in order to tighten it and to secure it against undesired and uncontrollable movements in the flow. The interior of the strand 4 could also be foamed with a plastic 19 in addition or while omitting the weighting filling in order to give the strand longitudinal rigidity.

Fig. 5 shows a section of a heat exchanger tube 1, which contains a hollow strand 4 in the form of a corrugated tube, on the surface of which elevations 12 and depressions 12 'are arranged, which run concentrically around the longitudinal axis of the tube.

6 shows in connection with FIGS. 6a, 6b and 6c a possibility of a strand 4 made of a sufficiently flexible material in the heat exchanger tube surrounding it 1 keep stable. The support is achieved here in that the strand 4 is rotated about its longitudinal axis after being inserted into the exchanger tube 1 and, if necessary, after the strand 4 has been fixed at the lower end of the tube 1, with slight compression, in such a way that it has the shape of a helix assumes and rests along a helical line of contact on the inner wall 18 of the exchanger tube 1 and is thus supported against movements possibly caused by the flow. Of course, the strand 4 twisted in this way must be secured at its (not shown) upper and lower ends in the exchanger tube 1 or on the upper and lower tube sheets of the tube bundle, which are also not shown, against turning back.

Reference list

1, 1 ', 1' '

Tubes of the tube bundle of a heat exchanger

2nd

upper tube plate / top plate of the tube bundle

3rd

lower tube sheet of the tube bundle

4th

Strand body / strand

5

upper end of the strand body (4)

6

thread-like profile of the strand body (4)

7

Internal cross section of the pipe (1)

8, 8 '

Pins for holding the strand (4)

9

lower end of the strand body (4)

10, 10 '

Leg of the U-shaped corrugated tube

11

U-shaped corrugated tube

13

Studs on strand body (4)

14, 14 '

widening cross section

15, 15 '

Inflow side of the heat exchanger tubes

16

Gluing the graphite tubes into a tube sheet of the tube bundle

17th

specifically heavy filling in the strand body (4)

18th

Inner wall of the tube (1)

19th

Filling in (4) made of foamed plastic

Claims (17)

Tube for tube bundle of heat exchangers with elements located inside the tube and generating turbulence in the flow in the tube
characterized in that
the inner wall of the tube (1) is free from elevations and depressions influencing the fluid flow in the tube (1)
and in the interior of the tube (1) there is a tubular or rod-shaped strand (4), the outer surface of which has the shape a) of a thread (6) or b) lying essentially transversely to the direction of flow in the tube (1) in the same way arranged shafts (12, 12 ') or c) is studded (13) or spikes,
that the strand (4), with the exception of at most linear contact with the inner surface (18) of the heat exchanger tube (1), is positioned at a distance from this inner surface (18),
so that there is a space between the strand (4) and the inner surface (18) of the heat exchanger tube (1) for the fluid to flow through the heat exchanger tube (1). Pipes (1, 1 ') arranged in pairs for tube bundles of heat exchangers with elements in the interior of the tubes (1, 1') which generate turbulence in the flow in the tubes,
characterized in that
the inner wall of the tubes (1, 1 ') is free of elevations and depressions which influence the fluid flow in the tubes (1, 1'),
that in the interior of the tubes (1, 1 ') there is a tubular or rod-shaped strand (4), the outer surface of which has the shape a) of a thread (6) lying essentially transversely to the direction of flow in the tubes (1, 1') or b) has shafts (12, 12 ') arranged in the same way or c) is equipped with knobs (13) or spikes,
that the strand (4) is positioned at a distance from these inner surfaces (18), with the exception of at most linear contact with the inner surfaces (18) of the heat exchanger tubes (1, 1 '),
so that there is a space between the strand (4) and the inner surface (18) of the heat exchanger tubes (1, 1 ') for a fluid to flow through the heat exchanger tubes (1, 1'),
that the strand (4) has a U-shape,
that the legs (10, 10 ') of the U of the strand (4) are located in two adjacent tubes (1, 1') of a heat exchanger and the bend of the U connecting the legs (10, 10 ') outside the tubes (1 , 1 ') is arranged. Pipe (1) according to claim 1,
characterized in that
the strand (4) is designed as a corrugated tube closed on at least one side. Pipe (1) according to claim 1,
characterized in that
the strand (4) consists of a material from the group consisting of thermoplastic, thermoset, elastomer, carbon, carbon fiber reinforced plastic, ceramic, metal, wood. Pipes (1, 1 ') according to claim 2,
characterized in that
the U-shaped strand (4) is designed as a corrugated tube. Pipes (1, 1 ') according to claim 2 or 5,
characterized in that
the strand (4) consists of a material from the group consisting of thermoplastic, thermoset, elastomer, metal. Pipe (1) or pipes (1, 1 ') according to one of the claims 1 to 3 or 5,
characterized in that
the strand (4) consists of a material from the group polytetrafluoroethylene, polyvinylidene fluoride, polypropylene, polyvinyl chloride. Pipe (1) or pipes (1, 1 ') according to one of the claims 1 to 7,
characterized in that
the tube (1) or the tubes (1, 1 ') at at least one of its ends or at the bores in the upper (2) or / and aligned with the tube (1) or the tubes (1, 1') the lower tube sheet (3) of the tube bundle has a cross-section (14, 14 ') which widens outwards and enlarges the flow cross-section. Pipe (1) or pipes (1, 1 ') according to one of the claims 1 to 8,
characterized in that
the largest outside diameter (a) of the strand (4) is 1/3 to 8/10 of the inside diameter (b) of the heat exchanger tube (1) or of the heat exchanger tubes (1, 1 '). Pipe (1) or pipes (1, 1 ') according to one of the claims 1 to 9,
characterized in that
the strand (4) is supported on the inner tube wall (18). Pipe (1) or pipes (1, 1 ') according to one of the claims 1 to 10,
characterized in that
the strand (4) passes through the tube (1) or the tubes (1, 1 ') in a spiral shape. Pipe (1) or pipes (1, 1 ') according to one of the claims 1 to 11,
characterized in that
when using a hollow strand (4) the cavity of the strand (4) is at least partially filled. Pipe (1) or pipes (1, 1 ') according to claim 12,
characterized in that
the cavity of the strand (4) is filled with at least one solidified mass. Pipe (1) or pipes (1, 1 ') according to one of the claims 1 to 13,
characterized in that
the tube (1) or the tubes (1, 1 ') consists of fluid-tight graphite. Use of pipes (1, 1 ') according to one of claims 1 to 14 for reducing the size of heat exchangers according to height / length or / and diameter by including the greater heat exchange capacity of pipes (1) according to the invention in the constructive design and construction of heat exchangers . Use of pipes (1, 1 ') according to one of the claims 1 to 14,
to increase the heat transfer capacity of heat exchangers compared to heat exchangers of the same construction, but the heat-exchanging tubes of which do not contain strands (4) according to the invention. Use of pipes (1, 1 ') according to one of the claims 1 to 14
instead of heat exchanger tubes which do not have any of the features of the invention described here and which have a smaller inside diameter than the heat exchanger tubes (1, 1 ') according to the invention.

Images