CN114763977A

CN114763977A - Flat pipe and heat exchanger

Info

Publication number: CN114763977A
Application number: CN202111613208.7A
Authority: CN
Inventors: 罗伯特·路易斯·润科; 斯科特·肯特
Original assignee: Mahle International GmbH
Current assignee: Mahle International GmbH
Priority date: 2021-01-13
Filing date: 2021-12-27
Publication date: 2022-07-19
Also published as: DE102022200215A1; US20220221226A1

Abstract

A flat tube for a heat exchanger has a tube body having an outer top surface and an outer bottom surface arranged opposite to each other by a thickness of the tube body, and two outer side surfaces arranged opposite to each other by a width of the tube body and connecting the outer top surface and the outer bottom surface. The tube body has a heat exchange portion extending in an extending direction, an angled portion extending in a transverse direction inclined with respect to the extending direction, and a bent portion connecting the heat exchange portion to the angled portion. The angled portion is arranged at a distance from the heat exchange portion in the offset direction. The curved portion has a first end region facing the heat exchange portion and a second end region facing the angled portion, the first end region having a first bend opposite the direction of offset, the second end region having a second bend along the direction of offset.

Description

Flat pipe and heat exchanger

Technical Field

The invention relates to a flat tube for a heat exchanger and to a heat exchanger having such a flat tube.

Background

In heat pump applications and heat exchangers with only one single channel, the problem is that the single channel may easily freeze under adverse environmental conditions. This problem can be solved, for example, by the refrigerant pressure drop in a heat exchanger block with flat tubes being increased, for example, by an increased deflection of the refrigerant in the heat exchanger block. The increase in pressure drop is closely related to the increase in boiling temperature of the refrigerant, whereby the temperature of the flat tubes or heat exchanger blocks can be increased and thus the risk of freezing can at least be reduced. This can be achieved, for example, by meandering or multi-circuit flow through the heat exchanger.

A heat exchanger with two inflow collectors and two outflow collectors is known from CN 103644685 a. The heat exchanger has two types of flat tubes stacked alternately on top of each other. Flat tubes of the second type are substantially straight. Flat tubes of the first type have sharp bends or folds near their longitudinal ends, in which the central heat exchange section of the respective flat tube merges into the angled section of these flat tubes. Thus, the first inflow collector and the first outflow collector are arranged in line with the flat tubes of the second type, and the second inflow collector and the second outflow collector are each arranged beside the flat tubes of the second type and are connected to the angled portions of the flat tubes of the first type.

However, sharp bends or folds near the longitudinal ends of the flat tubes (of the first type) lead to an increase in the internal mechanical stresses in the region of the sharp bends or folds. Therefore, such conventional flat tubes may be susceptible to material failure during their manufacture or during operation of the heat exchanger due to the coolant or refrigerant pressure to which they must be subjected during operation of the heat exchanger.

Disclosure of Invention

The present disclosure presents a new method for improving the flat tubes of a heat exchanger.

Accordingly, the present general inventive concept is to configure a bent portion of a flat tube for a heat exchanger to have a first bent portion and a second bent portion via which a heat exchange portion of the flat tube is incorporated into an angled portion of the flat tube.

Advantageously, this results in an increase in the bend radius as opposed to typical bent flat tubes, and thus allows the strength of the flat tubes to be increased and less likely to fail during manufacture or operation thereof.

The present invention relates to a flat tube for a heat exchanger, having a tube body which delimits at least one coolant channel through which a coolant or refrigerant can flow. The tube has an outer top surface and an outer bottom surface disposed opposite each other by a thickness of the tube and two outer side surfaces disposed opposite each other by a width of the tube, the outer side surfaces connecting the outer top surface to the outer bottom surface. It goes without saying that the expressions "outer top surface" and "outer bottom surface" merely refer to a preferred orientation of the flat tubes, wherein this orientation can deviate without departing from the scope of the invention. Thus, if applicable, the flat tubes in their operating position can be oriented with their outer bottom surfaces upward or downward or sideways with respect to gravity. The tube body has a heat exchange portion extending substantially in an extending direction. The tubular body has an angled portion extending substantially in a transverse direction inclined with respect to the direction of extension. Preferably, the first bend has an S-or Z-shape comprising two sub-bends, one of which is directed in the opposite direction of the deflection direction and one of which is directed in the deflection direction, wherein the two sub-bends together cause the tube body to retract against the deflection direction while moving away from the heat exchange portion in the extension direction. The tube body also has a bent portion connecting the heat exchanging portion to the angled portion. The angled portion is arranged at a distance from the heat exchange portion, the distance being measured in an offset direction substantially perpendicular to both the extension direction and the transverse direction. The bent portion has a first bend in a first end region thereof facing the heat exchange portion opposite to the offset direction. The curved portion has a second bend in the offset direction in a second end region thereof facing the angled portion. This allows the bent portion to have a particularly large bending radius, so that the mechanical strength of the flat tube can be enhanced and the manufacturing thereof can be simplified.

According to a preferred embodiment of the flat tube, the second bend is a twisted bend. Thereby, the inclination of the angled portion opposite the heat exchange portion and the distance between the angled portion and the heat exchange portion in the offset direction can be achieved in a single and thus inexpensive deformation process.

According to a further preferred embodiment of the flat tubes, the direction of extent runs along a substantially straight line. This allows a particularly efficient heat exchange.

In a further preferred embodiment of the flat tube, the transverse direction is substantially perpendicular to the direction of extent. The production costs of such flat tubes are particularly low.

In a further preferred embodiment of the flat tube, the angled portion is arranged opposite the heat exchange portion at a distance which is smaller than the minimum bending radius of the second bend. In this way, the mechanical load during bending of the flat tube into its final shape during the manufacturing process can be kept below the failure load.

According to a further preferred embodiment of the flat tube, the second bend has a minimum bend radius of 3 to 6 times the tube thickness. This ratio of the bending radius of the second bend to the tube thickness has proven to be particularly suitable. Additionally or alternatively, the second bend has a minimum bend radius of 0.70 to 0.95 times the tube width. Additionally or alternatively, heat transfer fins can be present at the outer top surface and/or the outer bottom surface, wherein the heat fins protrude from the respective outer top surface and/or the outer bottom surface along a fin height measured perpendicularly with respect to the respective outer top surface and/or the outer bottom surface, the minimum bend radius of the second bend being 0.70 to 0.95 times the fin height.

According to a further preferred embodiment of the flat tube, the tube body delimits a plurality of coolant channels arranged in a row along the width of the tube, wherein between immediately adjacent coolant channels there are separating walls extending along the thickness of the tube body. Such flat tubes allow a particularly uniform heat exchange distribution at their outer upper and bottom surfaces. Furthermore, such flat tubes can have a particularly small thickness.

In a further preferred embodiment of the flat tube, the tube body has a homogeneous material or consists of a homogeneous material, which is preferably metal. This enhances the heat transfer/exchange and allows the curved semi-finished straight flat tubes to match the geometry of the flat tubes according to this embodiment of the invention.

According to a further preferred embodiment of the flat tube, the curved portion has an S-shaped or Z-shaped geometry in a view perpendicular to the direction of extension and to the direction of offset. This means that if the first bend comprises two sub-bends which together form an S or Z shape, the second bend is gradually added to the S or Z shape to form the S or Z geometry of the bend. Thereby, the bending radius of the second bending portion can be increased.

The invention also relates to a heat exchanger having a first flat tube according to the invention as described above, wherein a longitudinal end of the angled portion of the first flat tube remote from the bent portion is received in an associated second opening of the second collector. The aforementioned advantages of the flat tube according to the invention are therefore correspondingly transmitted to the heat exchanger. The heat exchanger furthermore has second flat tubes, wherein first longitudinal ends of these second flat tubes are accommodated in associated third openings of the third collector and second longitudinal ends of the second flat tubes, which are arranged opposite to their first longitudinal ends, are accommodated in associated fourth openings of the first collector. The first opening and the fourth opening are arranged spaced apart from each other.

According to a preferred embodiment of the heat exchanger, the first flat tubes and the second flat tubes are arranged alternately in a stacking direction, which corresponds, in particular, to an offset direction of the first flat tubes. By arranging the flat tubes alternately, the defrosting capacity can be improved. Therefore, the defrost cycle can be shortened and the overall energy efficiency of the heat exchanger can be improved.

In a further preferred embodiment of the heat exchanger, an intermediate space is present between adjacent flat tubes, in which intermediate space the heat transfer fins are accommodated. This enhances the heat exchange/transfer between the fluid flowing through the intermediate space and the coolant or refrigerant flowing through the flat tubes, since the heat transfer fins effectively increase the heat exchange surface area of the heat exchanger.

Preferably, the heat transfer fins are held in place by the first bends while the heat exchanger is assembled.

According to a further preferred embodiment of the heat exchanger, the heat exchange portion of the first flat tube completely overlaps the second flat tube, while the angled portion of the first flat tube does not overlap, as seen in the stacking direction. This allows a particularly good heat exchange while maintaining the profile of the heat exchanger and a low air pressure drop.

In a further preferred embodiment of the heat exchanger, the second flat tube is substantially straight. Such a second flat tube can be easily removed from stock without any manufacturing or modification process being performed on it, except for cutting to length.

According to a further preferred embodiment of the heat exchanger, the second flat tube as well as the first flat tube correspond to the invention described above. Then, the transverse direction of the first flat pipe is different from the transverse direction of the second flat pipe. Such a heat exchanger can be provided in a particularly compact design.

Other important features and advantages of the present invention will become apparent from the accompanying drawings and the associated description of the drawings in which reference is made to the accompanying drawings.

It is to be understood that the features mentioned above and still to be explained below can be used not only in the respective combinations stated but also in other combinations or in isolation, without departing from the scope of the present invention.

Preferred exemplary embodiments of the invention are illustrated in the figures, and are described in more detail in the following description, wherein like reference numerals indicate identical or similar or functionally identical elements.

Drawings

Schematically showing:

fig. 1A shows an example of a flat tube according to the invention in a view opposite to the transverse direction;

FIG. 1B shows the example of FIG. 1A in a view along the offset direction;

fig. 2A shows a further example of a flat tube according to the invention in a view in the direction of the offset;

FIG. 2B shows the example of FIG. 2A in a view opposite the lateral direction;

FIG. 3A shows, in part, an example of a heat exchanger according to the invention in a view opposite to the transverse direction;

fig. 3B shows the first flat tube of the heat exchanger of fig. 3A in a view in the direction of the offset;

FIG. 4A shows the heat exchanger of FIG. 3A in a plan view along an offset direction; and

fig. 4B shows another example of a heat exchanger according to the invention in a plan view in the direction of the offset.

Detailed Description

Fig. 1A shows an example of a flat tube 1 according to the invention in a view opposite to the transverse direction 10, which flat tube 1 is configured to be implemented in a heat exchanger 30 according to the invention, which is shown in fig. 3A, 4A and 4B and described later. Fig. 1B shows the example of fig. 1A in a view along the offset direction 12. As can be seen from fig. 1A and 1B, the flat tube 1 has a tubular body 2 which delimits at least one coolant channel 3 through which a coolant or refrigerant can flow. In the example of fig. 1A, the pipe body 2 defines a plurality of coolant channels 3 arranged in a line along the width W of the pipe 1. A partition wall 17 extending along the thickness T of the pipe body 2 is present between two immediately adjacent coolant channels 3. For example, the tubular body 2 has a homogeneous material or consists of such a homogeneous material. The material of the pipe body 2 is, for example, metal.

Fig. 2A shows a further example of a flat tube 1 according to the invention in a view in the direction of the offset 12. Fig. 2B shows the example of fig. 2A in a view opposite to the transverse direction 10. In other words, the perspective view of fig. 2A corresponds to the perspective view of fig. 1B, and the perspective view of fig. 2B is similar to the perspective view of fig. 1A. For clarity and better understanding, the coolant channels 3 of the tubular body 2 are not shown in the example of fig. 2A and 2B.

As can be seen from fig. 1A, 1B, 2A and 2B, the tube body 2 has an outer top surface 4 and an outer bottom surface 5 which are arranged opposite to each other by a thickness T of the tube body 2. The tubular body 2 also has two outer lateral surfaces 6, which are arranged opposite each other with the width W of the tubular body 2. The outer side surface 6 connects the outer top surface 4 and the outer bottom surface 5. The tube body 2 has a heat exchange portion 7 extending substantially along an extension direction 8. The tubular body 2 has an angled portion 9 extending substantially along a transverse direction 10 inclined with respect to the direction of extension 8. The tube body 2 has a bent portion 11 connecting the heat exchanging portion 7 to the angled portion 9.

As can be seen from fig. 1A and 2B, the angled portion 9 is arranged at a distance D from the heat exchanging portion 7, which distance D is measured in the offset direction 12. The offset direction 12 is substantially perpendicular to both the extension direction 8 and the transverse direction 10. The bent section 11 has a first bend 14 which is present in a first end region 13 of the bent section 11 facing the heat exchange section 7. The first bend 14 of the curved portion 11 is curved opposite to the offset direction 12. Furthermore, the curved portion 11 has a second bend 16 which is present in a second end region 15 facing the angled portion 9. The second curved portion 16 is curved in the offset direction 12. In other words, in the first end region 13, the tubular body 2 is recessed back opposite to the heat exchange portion 7 in the direction opposite to the offset direction 12 due to the first bend 14. Therefore, in the second end region 15, the tubular body 2 protrudes from the heat exchanging portion 7 and the first end region 13 in the offset direction 12 due to the second bent portion 16. The curved portion 11 has, for example, an S-shaped or Z-shaped geometry 19. There can be a stepped bend 22 between the first bend 14 and the second bend 16 (see fig. 2A and 2B). The first bend 14 can have an S-or Z-shape consisting of two sub-bends, one of which points in the opposite direction of the offset direction and one of which points in the offset direction, wherein the two sub-bends together cause the tube body 2 to retract against the offset direction 12 while moving away from the heat exchange portion 7 in the extension direction 8. When the first bend 14 comprises two sub-bends, which together have an S-or Z-shape, the second bend 16 may gradually be added to the S-or Z-shape geometry in order to form the S-or Z-shape geometry 19 of the bend 11.

Additionally, fig. 1A, 1B, 2A and 2B show that the extension direction 8 runs along a substantially straight line. The transverse direction 10 in the example of fig. 1A, 1B, 2A and 2B is substantially perpendicular to the extension direction 8. It goes without saying that, as an alternative, the transverse direction 10 may be inclined at a different angle opposite to the direction of extension 8 than at right angles to fig. 1A, 1B, 2A and 2B. The transverse direction 10 can follow a straight line or a curved line. The distance D at which the angled portion 9 is arranged opposite the heat exchange portion 7 is smaller than the minimum bending radius R of the second bend 16. The minimum bending radius R of the second bending portion 16 is, for example, 3 to 6 times the tube thickness T of the tube body 2. The minimum bend radius R can be 0.70 to 0.95 times the tube width W. The minimum bending radius R can be determined by the inner height H of the bending portion 11, measured in the offset direction 12. When moving away from the heat exchanging section 7, the bent section 11 is first arranged to be recessed back by the first bend 14 in a direction opposite to the offset direction 12, then the bent section 11 is raised in the offset direction 12 starting from its second bend 16 in order to pass through the plane containing the heat exchanging section 7 and finally is transferred in the offset direction 10 into the angled section 9.

In fig. 1A, 1B, 2A and 2B, the second bend 16 is a twisted bend 18. This means that in the second bend 16 the tube body 2 is bent and twisted simultaneously, so that on the one hand the distance D between the angled portion 9 and the heat exchange portion 7 is bridged, while on the other hand the exactly same surface area of the tube body 2 representing the top surface 4 in the heat exchange portion 7 is projected in the area of the angled portion 9 to the bottom surface 5. Thus, the pipe body 2 can be twisted by 180 ° in the second bend 16.

As already mentioned, the flat tubes 1 can be used in a heat exchanger 30 according to the invention. In fig. 3A, an example of a heat exchanger 30 according to the invention is partially shown in a view opposite to the transverse direction 10. The heat exchanger 30 has first flat tubes 1 according to the invention, one of which is shown separately in fig. 3B in a view along the offset direction 12. Alternatively, the first flat tube 1 of the heat exchanger 30 may correspond to the example of fig. 1A, 1B, 2A and 2B described above. The first flat tubes 1 of the heat exchanger 30 each have a first longitudinal end 20 of their heat exchanger section 7, which faces away from their bent section 11.

Fig. 4A shows the heat exchanger 30 in a plan view along the offset direction 12. As can be seen from fig. 3A and 4A, the first longitudinal end 20 of the first flat tube 1 is received in an associated first opening 39 of the first collector 36 of the heat exchanger 30. Each of the first flat tubes 1 also has a second longitudinal end 21 of its angled portion 9, which faces away from its bent portion 11. These second longitudinal ends 21 are accommodated in associated second openings 40 of the second collector 37 of the heat exchanger 30. The heat exchanger 30 also has a second flat tube 31. These second flat tubes 31 have a first longitudinal end 32 which is received in an associated third opening 41 of the third collector 38 of the heat exchanger 30. The second flat tubes 31 also have second longitudinal ends 33, which are arranged opposite the first longitudinal ends 32 of these second flat tubes and which are accommodated in associated fourth openings 42 of the first collector 36 of the heat exchanger 30. The first opening 39 and the fourth opening 42 are arranged spaced apart from each other.

As can be seen in fig. 3A, heat transfer fins 34 can be present at the outer top surface 4 and the outer bottom surface 5, wherein the heat fins 34 project from the respective outer top surface 4 and the outer bottom surface 5 along a fin height HF. The fin height HF is measured perpendicularly with respect to the respective outer top and

bottom surfaces

4, 5. The minimum bending radius R of the second bending portion 16 is 0.70 to 0.95 times the fin height HF.

According to fig. 3A and 4A, in the heat exchanger 30, the first flat tubes 1 and the second flat tubes 31 are alternately arranged along a stacking direction corresponding to the offset direction 12 of the first flat tubes 1. For example, the stacking direction is equal to the offset direction 12 of the first flat tube 1. Between two adjacent

flat tubes

1, 31, an intermediate space 35 can be present in the heat exchanger 30, in which intermediate space the heat transfer fins 34 of the heat exchanger 30 are accommodated. In the view in the stacking direction, the heat exchange portion 7 of the first flat tube 1, for example, completely overlaps the second flat tube 31, while the angled portion 9 of the first flat tube 1 at least partially does not overlap the second flat tube 31. For example, second flat tube 31 may be substantially straight. For example, the heat transfer fins 34 can be held in place by the first bent portions 14 of the first flat tubes 1 while the heat exchanger 30 is assembled.

In an alternative example of a heat exchanger, which is shown as an example in fig. 4B in a plan view along the offset direction 12, the second flat tube 31 is configured substantially in accordance with the flat tube 1 of the invention as shown by way of example in fig. 1A, 1B, 2A and 2B and described above, wherein the transverse direction 10 of the first flat tube 1 differs from the transverse direction 10' of the second flat tube 31. Both the first flat tube 1 and the second flat tube 31 in the heat exchanger 30 can therefore correspond to the flat tube 1 according to the invention, wherein in the heat exchanger 30 they are installed in different, in particular mirror-image, orientations. In the example of fig. 4B, the first flat tube 1 and the second flat tube 31 are formed as identical components, which differ only in their orientation in the heat exchanger 30.

While the foregoing description constitutes the preferred embodiment of the present invention, it is to be understood that the invention is susceptible to modification, variation and change without departing from the proper scope and fair meaning of the accompanying claims.

Claims

1. Flat tube (1) for a heat exchanger (30), comprising a tube body (2) which delimits at least one coolant channel (3) for a coolant or refrigerant,

said tube having an outer top surface (4) and an outer bottom surface (5) arranged opposite each other with a thickness (T) of the tube (2), and having two outer side surfaces (6) arranged opposite each other with a width (W) of the tube (2), said outer side surfaces connecting the outer top surface (4) to the outer bottom surface (5),

Wherein the tube body (2) has a heat exchange portion (7) extending in an extension direction (8),

wherein the tube body (2) has an angled portion (9) extending in a transverse direction (10) which is inclined with respect to the extension direction (8),

wherein the tube body (2) has a curved portion (11) connecting the heat exchange portion (7) to the angled portion (9),

wherein the angled portion (9) is arranged at a distance (D) from the heat exchange portion (7) measured in an offset direction (12) perpendicular to both the extension direction (8) and the transverse direction (10),

wherein the curved portion (11) has a first end region (13) facing the heat exchange portion (7) and a second end region (15) facing the angled portion (9), the first end region having a first bend (14) opposite the offset direction (12) and the second end region having a second bend (16) along the offset direction (12).

2. Flat tube (1) according to claim 1, wherein the second bend (16) is a twisted bend (18).

3. Flat tube (1) according to claim 1, wherein the direction of extension (8) runs along a straight line.

4. Flat tube (1) according to claim 1, wherein the transverse direction (10) is perpendicular to the direction of extension (8).

5. Flat tube (1) according to claim 1, wherein the angled section (9) is arranged opposite the heat exchange section (7) at a distance (D) which is smaller than the minimum bending radius (R) of the second bend (16).

6. Flat tube (1) according to claim 5, wherein the second bend (16) has a minimum bend radius (R) of 3 to 6 times the tube thickness (T).

7. Flat tube (1) according to claim 1, wherein the tube body (2) delimits a plurality of coolant channels (3) arranged in line along the width (W) of the tube (1), wherein directly adjacent coolant channels (3) are separated by partition walls (17) extending along the thickness (T) of the tube body (2).

8. Flat tube (1) according to claim 1, wherein the tube body (2) comprises a homogeneous metallic material.

9. Flat tube (1) according to claim 1, wherein the curved section (11) has an S-shaped or Z-shaped geometry (19) in a view perpendicular to both the extension direction (8) and the offset direction (12).

10. A heat exchanger (30) comprising:

a first collector (36), a second collector (37), and a third collector (38);

First flat tubes (1) each having a tube body (2) which delimits at least one coolant channel (3) for a coolant or refrigerant,

the tube (2) having an outer top surface (4) and an outer bottom surface (5) arranged opposite each other with a thickness (T) of the tube (2), and having two outer side surfaces (6) arranged opposite each other with a width (W) of the tube (2), the outer side surfaces connecting the outer top surface (4) to the outer bottom surface (5),

wherein the angled portion (9) is arranged at a distance (D) from the heat exchange portion (7), the distance being measured in an offset direction (12) perpendicular to both the extension direction (8) and the transverse direction (10),

wherein the curved portion (11) has a first end region (13) facing the heat exchange portion (7) and a second end region (15) facing the angled portion (9), the first end region having a first bend (14) opposite the offset direction (12) and the second end region having a second bend (16) along the offset direction (12),

Wherein a first longitudinal end (20) of the heat exchange portion (7) facing away from the curved portion (11) is received in an associated first opening (39) of the first collector (36), and a second longitudinal end (21) of the angled portion (9) facing away from the curved portion (11) is received in an associated second opening (40) of the second collector (37);

a second flat tube (31), wherein a first longitudinal end (32) of the second flat tube (31) is received in an associated third opening (41) of the third collector (38), and a second longitudinal end (33) of the second flat tube (31), which is arranged opposite the first longitudinal end (32), is received in an associated fourth opening (42) of the first collector (36);

wherein the first opening (39) and the fourth opening (42) are arranged at a distance from each other.

11. The heat exchanger (30) according to claim 10, wherein the first flat tube (1) and the second flat tube (31) are arranged alternately in a stacking direction corresponding to the offset direction (12) of the first flat tube (1).

12. A heat exchanger (30) according to claim 11, wherein the heat exchanging portion (7) of the first flat tube (1) completely overlaps the second flat tube (31) and the angled portion (9) of the first flat tube (1) does not overlap in a view in the stacking direction.

13. A heat exchanger (30) according to claim 10, wherein an intermediate space (35) is present between adjacent flat tubes (1, 31), in which intermediate space the heat transfer fins (34) are accommodated.

14. A heat exchanger (30) according to claim 10, wherein the second flat tube (31) is straight.

15. The heat exchanger (30) according to claim 10, wherein each of the second flat tubes (31) has a tube body (2) defining at least one coolant channel (3) for a coolant or refrigerant,

wherein the tube body (2) has a heat exchange section (7) extending in an extension direction (8),

wherein the tube body (2) has an angled portion (9) extending in a transverse direction (10) which is inclined with respect to the direction of extension (8),

wherein the tube body (2) has a curved portion (11) connecting the heat exchanging portion (7) to the angled portion (9),

wherein the curved portion (11) has a first end region (13) facing the heat exchange portion (7), and a second end region (15) facing the angled portion (9), the first end region (13) having a first bend (14) opposite to the offset direction (12), the second end region (15) having a second bend (16) along the offset direction (12),

wherein the transverse direction (10) of the first flat tube (1) is different from the transverse direction of the second flat tube (31).