KR20160042182A - Tube for a heat exchanger - Google Patents

Abstract

The present invention relates to a tube for a heat exchanger, which has an area having dimples according to a certain pattern to increase the degree of heat exchange while lowering a pressure drop. The tube for a heat exchanger according to the present invention is especially beneficial to heat exchangers for an exhaust gas recirculation (EGR) system. Moreover, the present invention is beneficial to environment as the efficiency of the heat exchangers designed to use the tube is increased.

Description

Tube for a heat exchanger

The present invention relates to a tube for a heat exchanger comprising an area having dimples according to a predetermined pattern so as to increase the heat exchange rate while the pressure drop is low.

Heat exchangers are devices that promote heat transfer between two fluids passing through an exchange surface that prevents mixing of two fluids. The amount of heat transferred is proportional to the exchange surface and is also proportional to the exchange rate per unit area.

The heat exchange rate per unit area mainly depends on flow conditions and fluid properties around the heat exchange surface. Considering that the convection heat transfer mechanisms are much more effective than the diffusion heat transfer mechanisms, the solutions used in the art seek to promote convection near the exchange surface.

One of the ways to increase convection near the exchange surface is to use fins. The most widely used pins are protrusions in the form of plates emerging from the surface. The fins have a dual effect on the flow flow in the vicinity of the exchange surface, with the first effect being that in addition to the area on both sides of the pin, the exchange surface remains the same except for the area in which the pin occurs, And the second effect is an increase in turbulence near the exchange surface.

The increase in turbulence results in the generation of vortices with small characteristic diameters creating moving structures that facilitate mass exchange between regions near the exchange surface and away from where the main flow is located , Which results in increasing convective effects and ultimately increasing convective heat transfer between the exchange surface and the fluid.

This clear advantage has the problem of increasing heat exchange but also increasing pressure drop. The heat exchange area is formed by the tubes passing through the first fluid and is heat exchanged, and then when the tubes are immersed in a second fluid contained in the shell, a pressure drop is generated between the shell inlet and the outlet and between the tube inlet and outlet Lt; / RTI >

High pressure drop requires higher propulsion energy. The pressure drop makes it possible to establish the overall efficiency of the heat exchanger with the heat exchange rate. An effective heat exchanger therefore requires a low pressure drop as well as a high heat exchange rate.

The high heat exchange rate, as an example, makes it possible to reduce the volume required to accommodate the exchange surface for specific heat exchange requirements.

Certain types of tubes for heat exchangers using pins are hybrid tubes, pins and tubes, or pins and plates known in the art. Hybrid tubes are tubes formed by sheet metal, the shape of which is a planar shape, that is, a shape along its cross-section, with two parallel planar portions that are laterally closed by curved portions.

The interior of these tubes having a planar shape has a second portion formed by a sheet with several bends forming the fins, the sheet being sandwiched between two planar surfaces.

Such tubes are very effective with regard to exchange rates but have certain problems due to the thermal expansion effect of the inner sheet, for example, such expansion can cause fatigue in the areas that produce stress. This is the case for the tube stitching area, for example where the expansion of the inner part is limited by the staking.

An alternative to such tubes is a tube having a planar shape that includes dimples on at least one of its faces. The dimples are not as effective as the pins because they can not be as compact and can not increase the exchange area to the same degree, but have the advantage of increasing the tube stiffness without having the expansion problems shown above.

A common method of manufacturing such tubes is based on a draw sheet that is subsequently bent along the longitudinal direction until the tube is closed. The tube is closed by a longitudinally extending weld bead which, in one example, joins the opposing edges.

The presence of dimples increases the turbulence and therefore the heat transfer rate. Flat tubes formed by dimples with various dimple patterns increasing the heat exchange rate are known.

Patterns deformed downstream are also known to account for flow deviations due to the influence of the upstream dimples. However, since the same mold can not be used for ejection along the entire length of the tube, or because actuators are needed in the machines to deform the depth of the dimples as the sheet-laying operation proceeds to obtain the tube, Making tube manufacturing difficult.

These patterns increase the heat transfer rate, but also increase the pressure drop.

The present invention relates to a tube comprising dimples for increasing the heat transfer rate so as to overcome the problems specified above by using a dimple pattern which combines a high heat exchange rate and a low pressure drop.

The present invention relates to a tube for a heat exchanger comprising an area having dimples according to a predetermined pattern so as to increase the heat exchange rate while the pressure drop is low.

Particularly advantageous is the use of the heat exchange tubes according to the invention in heat exchangers for exhaust gas recirculation (EGR) systems. The present invention is also considered to be beneficial to the environment because it increases the efficiency of the designed heat exchangers.

A heat exchange tube according to the present invention is a flattened tube having a first essential plane and a second essential plane parallel to the first surface and spaced from the first surface. Therefore, the flattened shape of the tube should be understood by the presence of the first plane and the second plane arranged parallel to each other, and both sides being connected by the side walls. The sidewalls may have any shape, but most common embodiments use a shape in the semicircular portion along the cross-section of the tube.

At least one side has a plurality of dimples shaped according to a pattern repeated along the longitudinal axis X-X 'of the tube. The longitudinal direction of the tube is the direction in which the dichroic line of the tube extends.

The pattern is shaped by dimple alignment of a plurality of groups covering the width of the plane. The dimples typically have a fillet radius at the root so that stamping does not produce excessive residual stresses or deformation does not weaken the sheet. The indication that the dimple radii cover the width of the plane creates an interval between the dimples or the walls of the tubes since the fillet radius creates a specific gap between the walls of the tubes. It should be understood that there may be an area or a pass-through channel.

The arrangements of the plurality of groups are:

Longitudinal direction  Aligned in the same direction Y-Y 'arranged at an angle between 40 and 50 degrees with respect to X-X', said tube comprising at least:

Two dimples, i. E. A first elongated dimple, aligned with the first point dimple and extending in the oblique direction Y-Y ', so that the first flow channel is between the elongated dimple and the point dimple Lt; RTI ID = 0.0 > 1, <

A second point dimple, a fourth point dimple and a fifth point dimple, which are essentially aligned according to the oblique direction Y-Y ', as a result of which the second point dimple, A flow channel is established between the second point dimple and the third point dimple, a third flow channel is established between the third point dimple and the fourth point dimple, and a fourth flow channel is formed between the fourth point dimple A second group constructed between a fifth point dimple and a fifth point dimple,

- a second point dimple aligned with the second elongated dimple extending in the oblique direction Y-Y ', so that the fifth flow channel is formed by the sixth point dimple and the second elongated dimple, A third group constructed between the dimples,

- Four point dimples, that is to say formed by seventh dimples, eighth dimples, ninth dimples and tenth dimples, which are essentially aligned by said oblique direction Y-Y ', so that the sixth flow channel A seventh point dimple and an eighth point dimple, a seventh flow channel being constructed between the eighth point dimple and the ninth point dimple, and an eighth flow channel being constructed between the seventh point dimple and the eighth point dimple, And a fourth group constructed between the dimples,

Wherein the position of said first flow channel is such that said flow, which equally passes in an operating mode, is primarily directed towards said third flow channel and said fourth flow channel.

The pattern includes extended dimples and point dimples. The elongated dimples have a preferred orientation. And when the group of dimples appears as aligned in a particular direction, it should be understood as extending dimples extending along the alignment direction, and further, except for possible small deviations, the axis along which they extend also passes through the positions of the point dimples do.

The pattern formed by the groups formed by the plurality of dimples has an oblique direction Y-Y 'toward one side and the same side. This orientation would likewise result in an inclined velocity component, but does not rearrange the overall flow in this direction. The strategic location of the sites with continuity between the dimples of successively arranged groups is oriented in the longitudinal direction or in the oblique direction, but according to the symmetry defined by the longitudinal axis X-X ' , Creating more desirable pass channels oriented at an opposite slope with respect to the slant direction Y-Y '.

Alternating in a direction different from the direction of inclination of the one side increases the local turbulence and in turn allows significant flow through the channels thus specified. According to the art, the presence of a large number of dimples increases the turbulence, but since the dimples are protrusions that penetrate the tube, it reduces the effective section of the tube and increases resistance to passage.

While this particular form according to the invention maintains a large number of dimples with a high degree of turbulence effect, the formation of channels as constructed in accordance with the particular dimple pattern according to the invention, The effective section is not significantly reduced because the pressure drop maintains a low flow.

The formation of the more preferred passage channels depends not only on the relative location of the spaces between the dimples downstream of the particular channel but also on the influence of the other surrounding dimples. The final operation of a particular dimple design can not be predicted because of this strong link between neighboring dimples both in the side and in the downstream and upstream flow directions, and as in the case where there is a change from one pattern to the next in the downstream flow, Much less so when the use of patterns that can be regenerated periodically along the length of the tube is beneficial.

The only way to determine whether a pattern meets effective goals, i.e., high heat transfer with little loss, is by flow simulation in a tube containing the proposed pattern. The simulation may be performed, for example, by numerical models (Computational Fluid Dynamics) simulations. The simulations allow numerical experiments to be performed to evaluate heat transfer and flow behavior, but in contrast, comparison with other known patterns does not allow estimation of results.

It has been demonstrated that the patterned article of the present invention effectively solves the above-described disadvantages. The combination of the distribution of the groups of dimples in one direction combined with the channels formed between the successively disposed sets extends the distance less than is known in the art depending on the direction perpendicular to the plane in which the dimples are arranged It has been proved that it has a perturbation effect on the surrounding flow. This permits symmetrical placement in the two opposing sides of the tube in order to continue to maintain the increase in heat exchange by the pattern shown by using the pattern in a single plane; That is, the flow deformed by the pattern on one surface does not negatively interfere with the flow deformed by the dimple patterns on the opposite surface, that is, they are generated in different patterns when they are positioned opposite each other.

The form of the pattern proposed by the present invention produces vortices that are generated downstream of the dimples that are homogenized as a result of the fluid flow being built to pass through certain desired channels created in the spaces between the dimples. In particular, the S-shaped or similarly shaped path with vortices successfully increases the heat exchange and consequently compensates for the pressure drop by the dimples.

The use of the heat exchange tubes according to the invention in heat exchangers for exhaust gas recirculation (EGR) systems is particularly advantageous. The present invention is also considered to be beneficial to the environment because it increases the efficiency of the heat exchangers designed to use the tubes.

BRIEF DESCRIPTION OF THE DRAWINGS Other advantages and features of the present invention will become more apparent from the following detailed description of preferred embodiments thereof, given by way of example only, and with reference to the accompanying drawings, in which: FIG.
Figure 1 shows a top view of a tube including an alignment of patterns along the length X-X ', according to an embodiment of the present invention.
Fig. 2 shows a comparison of the heat transfer when it is only caused by conduction and the number of turns (< RTI ID = 0.0 > n) < / RTI > for determining the increase in heat transfer at the surface comprising a plurality of patterns according to the embodiment shown in Fig. Nusselt number) Displays a deviation map.
Fig. 3 shows a tube having two planes repeating along the length of the tube, as in the example shown in Fig. The figure shows a pattern of the opposite side of the invisible side shown by the two patterns superimposed on each other, that is, the pattern of the visible side shown by the solid lines and the dotted lines.

According to a first aspect of the present invention, there is provided a tube for a heat exchanger exhibiting high convective heat transfer without significant pressure drop. The shape of the tube is formed by planar, i.e., parallel, flat surfaces connected in two sides, wherein there are a plurality of dimples according to a predetermined pattern located on one or both planes.

Figure 1 shows a tube according to an embodiment having a flattened form. In this embodiment, the pattern comprises a plurality of dimples A, B, 1, 2, 3, 4, 5, 6, 7, 8, 9 formed in accordance with a pattern repeated along the longitudinal direction X- 9 and 10, respectively. The direction X-X 'is the longitudinal direction of the tube.

The group of dimples may be repeated as many times as necessary along the length of the tube.

The pattern is constituted by dimple arrays of a plurality of groups covering the width of the plane, taking into account the fact that there is a fillet radius between the side dimples and the edge. The alignments of the plurality of groups are aligned in one direction and in the same direction Y-Y ', which are disposed at an angle between 40 and 50 degrees with respect to the longitudinal direction X-X'. In the embodiment shown in FIG. 1, the angle of the tilt axis Y-Y 'is 45 degrees.

In particular, the pattern is formed by at least four groups.

The first group is formed by two dimples (A, 1), a first extending dimple (A) extending along the oblique direction Y-Y 'aligned with the first point dimple (1) As a result, a first flow channel (C1) is constructed between the extended dimple (A) and the point dimple (1).

The flow channel is a gap between the dimples, i.e., the first extending dimple (A) and the first point dimple (1). Hereinafter, the flow channel will be understood as gaps between the dimples.

The flow can pass through the position of the dimple because the dimple does not reach the opposite wall of the tube. Nevertheless, this causes inclined speed components. The passage channels are not subject to the burden of converting a portion of the flow to the slope opposite the Y-Y 'axis with respect to the X-X' axis to the side and allowing the longitudinal or even sloped track to recover.

The second group is formed by four point dimples: a second point dimple (2), a third point dimple (3), a fourth point dimple (4) and a fifth point dimple (5) The second flow channel C2 is arranged between the second point dimple 2 and the third point dimple 3 and the third flow channel C2 is arranged between the third point dimple 3 and the third point dimple 3. [ C3 is constructed between the third point dimple 3 and the fourth point dimple 4 and the fourth flow channel C4 is formed between the fourth point dimple 4 and the fifth point dimple 5, Lt; / RTI >

As described above, the second channel (C2), the third channel (C3) and the fourth channel (C4) need not be completely supplied by the channels disposed upstream, but the main flow Lt; / RTI > For this reason, such a complex reaction of the flow to a given pattern occurs. In this particular case, when describing all the elements forming the pattern, the method of sorting the different flow channels formed between the dimples determining other effects on the flow, as specified below, is particularly interesting It is.

The third group is formed by a sixth point dimple 6 aligned with a second elongated dimple B extending along the two dimples 6, B, i.e. in the oblique direction Y-Y ' As a result, a fifth flow channel (C5) is constructed between the sixth point dimple (6) and the second elongated dimple (B).

The fourth group is formed by four point dimples, i.e., a seventh dimple 7, an eighth dimple 8, a ninth dimple 9 and a tenth dimple, So that the sixth flow channel C6 is constructed between the seventh point dimple 7 and the eighth point dimple 8 and the seventh flow channel C7 is arranged between the eighth point And an eighth flow channel C8 is constructed between the ninth point dimple 9 and the tenth point dimple 10. The sixth point dimple 9 is formed between the dimple 8 and the ninth point dimple 9,

It is important to emphasize the similarity of these groups with the first and second groups when specifying the third group and the fourth group. Nevertheless, since the similarity maintains the inclination in the same direction, the extended dimples B in the third group are not located at the upstream instead of upstream, as in the first group, It is not by repetition rate because it is located at the starting point of alignment.

In other words, as a result, the alignment of all the groups follows the same slope, but the specific alignment of the channels present between the dimples along the flow direction is not. Although the channel is formed by the passage between the two dimples, the channel is considered to be oriented in a direction perpendicular to the line connecting the center points of the two point dimples. In general, the orientation of the channel will be perpendicular to the line connecting the two dimples, where the connection is between the regions closest to each other.

1, the position of the first flow channel C1 is such that the flow passing through the same place in the operating mode is mainly directed to the third flow channel C3 and the fourth flow channel C4 It is observed to be transported. This branch affects the direction in which half of the pattern disposed downstream by the third and fourth groups is fed.

It is noted that the four groups have an oblique orientation and that the channels formed between the dimples constitute velocity components with transverse components that produce oblique flows for the opposite gradient in the Y-Y 'direction . In this embodiment, in a second group formed of four point dimples that are essentially aligned in the oblique direction Y-Y ', the second point dimples (2) and the third point dimples (3) A pair of dimples are aligned in the oblique direction Y-Y ', and a second pair of dimples formed by the fourth point dimple 4 and the fifth point dimple 5 are aligned in the oblique direction Y-Y' And the alignment of the first pair and the alignment of the second pair are parallel but offset by a certain distance.

This misalignment is shown in Figure 1 by two closely parallel lines Y-Y '. The technical effect is a change in the direction of the third channel C3 causing a higher degree of tilt in the opposite direction of the tilt of the axis Y-Y ', so that a higher flow rate is applied to the dimples of all groups And is directed to the fifth channel (C5) located close to the opposite side of the tilted axis of the axis Y-Y 'that is imposed. The fifth channel C5 supplies a passage through the remaining channels located mainly downstream, resulting in greater flow uniformity through all the dimples, with the result that the largest possible exchange area is used.

This technical effect is obtained with the configuration of the fourth group of point dimples, and the point dimples are essentially aligned according to the oblique direction Y-Y '. The first pair of dimples formed by the seventh point dimple (7) and the eighth point dimple (8) are aligned in the oblique direction Y-Y ', and the ninth dimple (9) and the tenth dimple The second pair of dimples formed by the first pair of electrodes 10 are aligned in the oblique direction Y-Y ', and the alignment of the first pair and the alignment of the second pair are parallel but offset.

This form can more easily homogenize the flow when the pattern is repeated periodically downstream.

The more preferable path generation along the slope opposite to the slope established by the axis Y-Y 'is such that the first flow channel C1, the third flow channel C3 and the fifth flow channel C5 are indispensable Lt; / RTI > This preferred path provides a flow in which the tilt of the axis Y-Y 'also reaches the opposite side of the side that provides its deflection.

This configuration, with the alignment of the three channels, namely the first flow channel C1, the third flow channel C3 and the fifth flow channel C5, has the advantage that when the pattern is repeated periodically downstream, Also contribute to.

Also, the above-described pattern can be shaped as shown in FIGS. 1 and 3, so that the pattern can be formed between the first channel (C1), the fourth channel (C4) and the eighth channel (C8) . These three channels form a more desirable path for the longitudinal guide of the flow, so as not to tend to over-orient the pattern, i.e., outside the sidewall of the tube. In the alignment of these three channels C1, C4, and C8, the third group of extended dimples B are interposed between the fourth channel C4 and the eighth channel C8. Nevertheless, this intervention does not interfere with the effectiveness of the alignment, as shown above, since the flow reaching the channel is supplied by the main flow of the tube as well as the flow from the channels disposed upstream.

Considering that a more desirable path is formed between the dimples by the alignment of the channels, the path is wavy and improves the swirl generation, resulting in an increase in the heat exchange rate with the surface of the tube as an immediate result.

Additionally, the pattern according to this embodiment can be used to construct alignment of the second channel (C2), the fifth channel (C5) and the sixth channel (C6) The slope greatly enhances the generation of the desired paths on the opposite side of the side that provides its deflection.

In this example, the second point dimple (2), the fifth point dimple (5), the seventh point dimple (7) and the tenth point dimple (10) And extends in the lateral direction. The technical effect of this expansion is the extension of the dimples towards the sides of the tube so that the main flow does not find the desired path for passage through these sides and is collected in the area of the dimples to increase heat exchange.

In this embodiment, the pattern shown in Figure 1 is repeated on the opposite surface. When comparing the pressure drop with that obtained in an embodiment having only the dimple pattern on only one side of the tube, the projection along the plane transverse to the tube causes the dimples to extend to one third Numerical simulations demonstrate that the pressure drop due to the interposition of the dimple pattern on one side is not greater than the double value even when it appears to have a decreasing depth. In other words, it is more desirable that the heat transfer: pressure drop ratio has a dimple pattern on both sides of the tube rather than just having a pattern on one side.

This means that the flow perturbations caused by the dimples on one side do not have a negative impact on the pressure drop on the other side. This effect will make the depth of the dimples less than in the cross sections which are proportionally smaller than shown.

FIG. 2 is a Nusselt number value on the surface of the tube, showing a high number of yarn counts uniformly observed in all the dimples. This represents a significant increase in heat transfer at the surface compared to all of these with heat transfer and reduced pressure drop caused by conduction only for the position corresponding to the dimples.

The value of the number of cylinders is obtained by the following ratio:

는, 상기 튜브의 유압 반경,

는, 상기 튜브의 전도율, 그리고

는, 상기 필름 계수 값, 또는 다음 비율에 따른 대류 열전달 계수 있다.here

The hydraulic radius of the tube,

The conductivity of the tube, and

Is the film coefficient value, or a convective heat transfer coefficient according to the following ratio.

는, 상기 대류과정에서 전달된 열 파워,

는 상기 튜브의 벽 온도, 그리고

는 상기 튜부의 고온 가스 유입구에서의 온도에 대응되는 참조 온도 값이다.here

The heat power transferred in the convection process,

The wall temperature of the tube, and

Is a reference temperature value corresponding to the temperature at the hot gas inlet of the tub.

의 값으로서 사용되었다.In the example shown in Fig. 2, 6.75 mm is the hydraulic radius

.

값으로서 사용되었다.In the example shown in Figure 2, 673.15 K is the reference temperature

Lt; / RTI >

Therefore, the figure shows the distribution of the number of heat cycles as a function of the heat transfer generated in the passage of the hot gas flow through the tube, i.e. in the direction shown in the figure.

The dimple pattern of these features will be a very effective tube when it is part of the heat exchanger according to the transmitted thermal power values, as described by representative nucell number values.

Figure 3 shows a tube having the same pattern as the example shown in Figure 1 in which two planes are repeated along the length of the tube. This figure shows two patterns superimposed on each other, the pattern of which is shown by the solid line and the pattern of the invisible face on the opposite side is shown by the dotted line. In order to more easily specify the dimples on the two faces, the reference numbers of the visible faces are located on each dimple while the numbers of the dimples located on the invisible face are located outside the region occupied by the city of the tube .

The pattern of the first surface and the pattern of the second surface are distributed longitudinally and as a result extend to the same length. In this case, it is not only because the dimples have the same size, but also because the distributions shown on the two sides occupy the same length.

Wherein the pattern of the first face and the pattern of the second face are formed so as to be parallel to the end of the first elongated dimple (A) positioned closest to the central axis of the tube of the first face and the center axis of the tube of the second face The ends of the second elongated dimples B positioned closest to each other are positioned so as to overlap each other according to the projection degree in a plane parallel to both sides. In this way, the flow perturbations due to the presence of dimples on one side show that they do not seriously affect the deformed flow due to the presence of the dimples on the opposite side.

Claims (10)

- a flattened form comprising a first mandatory plane and a second mandatory plane parallel to and spaced from said first face; The two sides are connected by sidewalls and at least one side comprises a plurality of dimples A, B, 1, 2, 3, 4, 5 , 6, 7, 8, 9, 10), the pattern being shaped by dimple arrays of a plurality of groups covering the width of the plane, Aligned in the same direction Y-Y ', and at least there is at least one of:
- two dimples (A, 1), i.e., formed by a first elongated dimple aligned with the first point dimple (1) and extending in the oblique direction Y-Y ', so that the first flow channel A first group constructed between said elongated dimples (A) and said point dimples (1)
A second point dimple 2, a third point dimple 3, a fourth point dimple 4 and a fifth point dimple 4, which are essentially aligned according to the oblique direction Y-Y ' 5) so that a second flow channel (C2) is constructed between the second point dimple (2) and the third point dimple (3), and the third flow channel (C3) A second point dimple (4) and a fifth point dimple (5) are constructed between a three point dimple (3) and the fourth point dimple (4) group,
Is formed by two dimples (6, B), i.e. a sixth point dimple (6) aligned with a second elongated dimple (B) extending in the oblique direction Y-Y ' A third group in which the flow channel C4 is constructed between the sixth point dimple 6 and the second extending dimple B,
By the seventh dimple 7, the eighth dimple 8, the ninth dimple 9 and the tenth dimple 10, which are essentially aligned by the four point dimples, i.e., in the oblique direction Y-Y ' And as a result a sixth flow channel C6 is constructed between the seventh point dimple 7 and the eighth point dimple 8 and a seventh flow channel C7 is formed between the eighth point dimple 8 ) And the ninth point dimple (9), and an eighth flow channel (C8) is constructed between the ninth point dimple (9) and the tenth point dimple (10) ,
Wherein the position of said first flow channel (C1) is such that the flow through said heat exchanger tube, in which said flow essentially equally passes in said operating mode, is transported towards said third flow channel (C3) and said fourth flow channel . The method according to claim 1,
- a first pair of dimples (2) formed by the second point dimples (2) and the third point dimples (3) in a second group formed of essentially point aligned dimples according to the oblique direction Y-Y ' The second pair of dimples formed by the fourth point dimple 4 and the fifth point dimple 5 are aligned in the oblique direction Y-Y ', and the second pair of dimples formed by the fourth point dimple 4 and the fifth point dimple 5 are aligned in the oblique direction Y- Wherein the first pair of alignments and the second pair of alignments are parallel but offset a predetermined distance. The method according to claim 1 or 2,
- a first pair formed by the seventh point dimple (7) and the eighth point dimple (8) in a fourth group formed by essentially four point dimples aligned in the oblique direction Y-Y ' And the second pair of dimples formed by the ninth dimple 9 and the tenth dimple 10 are aligned in the oblique direction Y-Y ' And wherein the first pair of alignments and the second pair of alignments are parallel but offset. The method of any one of the preceding claims,
- a tube in which the first flow channel (C1), the third flow channel (C3) and the fifth flow channel (C5) are essentially aligned. The method of any one of the preceding claims,
A tube in which the first channel (C1), the fourth channel (C4) and the eighth channel (C8) are essentially aligned. The method of any one of the preceding claims,
A tube in which the second channel (C2), the fifth channel (C5) and the sixth channel (C6) are essentially aligned. The method of any one of the preceding claims,
- the second point dimple (2), the fifth point dimple (5), the seventh point dimple (7) and the tenth point dimple (10) intersect in the oblique direction Y-Y ' Expanded tubing. The method of any one of the preceding claims,
The tube having one pattern and the same pattern on the first surface and the second surface. The method of any one of the preceding claims,
At least one pattern along a length of the tube in a first plane and at least one pattern along a length of the tube in a second plane or opposite plane,
The pattern of the first face and the pattern of the second face are distributed in the longitudinal direction so that they extend to the same length
Wherein the pattern of the first face and the pattern of the second face are arranged such that the end of the first elongated dimple (A) located closest to the center axis of the tube of the first face and the center of the tube of the second face And the end of the second elongated dimple (B) positioned closest to the first elongated dimple (B) is positioned so as to overlap with each other in projection in a plane parallel to both sides. - a heat exchanger comprising one or more tubes according to any one of the preceding claims.

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