DE102022200215A1 - Flat tube and heat exchanger - Google Patents

Abstract

A flat tube for a heat exchanger has a tube body with an outer upper and an outer lower surface, which are arranged opposite to each other at a thickness of the tube body, and two outer side surfaces, which are arranged opposite to each other at a width of the tube body and the outer upper and connect lower surface, on. The tube body has a heat exchange portion extending along an extending direction, an angled portion extending along a transverse direction inclined relative to the elongating direction, and a bent portion connecting the heat exchanging portion to the angled portion. The angled portion is spaced apart from the heat exchanging portion in an offset direction. The bent portion has a first end portion facing the heat exchange portion with a first bend against the offset direction and a second end portion facing the angled portion with a second bend in the offset direction.

Description

TECHNICAL AREA

The invention relates to a flat tube for a heat exchanger and a heat exchanger that has such flat tubes.

BACKGROUND ART

In heat pump applications and heat exchangers that only have a single pass, it is a problem that under unfavorable conditions the single pass can easily freeze. This problem could be solved in that, for example, a refrigerant pressure drop in a heat exchanger core having flat tubes, e.g. B. is increased by an increased deflection of the refrigerant in the heat exchanger block. An increase in the pressure drop goes hand in hand with an increase in a boiling temperature of the refrigerant, as a result of which the temperature of the flat tubes or the heat exchanger block can be increased and consequently the risk of freezing can be at least reduced. This can be achieved, for example, by a meandering or multi-loop flow through the heat exchanger.

Of CN 103 644 685 A a heat exchanger is known which has two inlet headers and two outlet headers. This heat exchanger has two types of flat tubes that are alternately stacked on top of each other. A second type of flat tubes are essentially straight. The flat tubes of the first type have a sharp bend near their longitudinal ends, in which bend or crease a central heat exchange section of the respective flat tubes merges into an angled section of these flat tubes. Accordingly, a first of the inflow and a first of the outflow headers are arranged in line with flat tubes of the second type, and a second of the inflow and a second of the outflow headers are respectively arranged adjacent to the flat tubes of the second type and with the angled portions of the connected to flat tubes of the first kind.

However, the sharp bend or crease near the longitudinal ends of the flat tubes (of the first type) leads to increased mechanical stresses in the area of the sharp bend or crease. Consequently, such conventional flat tubes can be susceptible to material failure either during their manufacture or during the operation of the heat exchanger due to the coolant or refrigerant pressure they must withstand when the heat exchanger is in operation.

EXECUTIVE SUMMARY

The present invention provides new avenues for the development of flat tubes for heat exchangers.

A general idea of the invention is therefore to configure the bent section of the flat tube for a heat exchanger in such a way that it has a first and a second bend, via which a heat exchange section of the flat tube merges into an angled section of the flat tube.

Advantageously, this results in an increased bend radius over that of conventional flat tubing and consequently allows for improved strength of the flat tubing and less likelihood of failure during its manufacture or service.

The invention relates to a flat tube for a heat exchanger, which has a tube body that delimits at least one coolant channel through which a coolant or refrigerant can flow. The tubular body has an outer upper and an outer lower surface which are arranged opposite to each other at a thickness of the tubular body, and two outer side surfaces which are arranged opposite to each other at a width of the tubular body, the outer side surfaces combining the outer upper with the connect outer lower surface. It goes without saying that the expressions "outer upper surface" and "outer lower surface" only refer to a preferred orientation of the flat tube, which orientation can be deviated from without departing from the scope of the invention. Thus, if practicable, the flat tube may be oriented in its operative position with its outer lower surface facing up or down or sideways with respect to gravity. The tube body has a heat exchange portion that extends substantially along an extension direction. The tubular body has an angled portion that extends substantially along a transverse direction that is inclined with respect to the direction of extension. Preferably, the first bend has an S- or Z-like shape comprising two sub-bends, one directed against the direction of offset and one directed in the same, the two sub-bends together causing the tubular body to bend opposite to that Displacement direction recedes while moving away from the heat exchange portion in the spanwise direction. The tube body also has a bent portion connecting the heat exchange portion to the bent portion. The angled portion is spaced from the heat exchange portion as measured in an offset direction substantially perpendicular to both the spanwise and transverse directions. The bent portion has a first bend opposite to the offset direction in its first end portion opposite to the heat exchanging portion. In its second end region opposite the angled portion, the bent portion has a second bend in the offset direction. This allows the bending radius of the bent portion to be particularly large, so that the mechanical strength of the flat tube can be improved and its manufacture can be simplified.

According to a preferred embodiment of the flat tube, the second bend is a twist bend. As a result, both the inclination of the angled section relative to the heat exchange section and the distance between the angled section and the heat exchange section along the offset direction can be achieved in a single and consequently inexpensive deformation process.

According to another preferred embodiment of the flat tube, the direction of extension essentially follows a straight line. This enables a particularly effective heat exchange.

In another preferred embodiment of the flat tube, the transverse direction is substantially perpendicular to the direction of extension. Such a flat tube is particularly inexpensive to produce.

In another preferred embodiment of the flat tube, the distance at which the angled portion is located is less than a minimum bend radius of the second bend. In this way, a mechanical stress when the flat tube is bent to its final shape during manufacture can be kept below a breaking load.

According to another preferred embodiment of the flat tube, the minimum bending radius of the second bend is 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 as an alternative, the minimum bend radius of the second bend is 0.70 to 0.95 times the tube width. Additionally or as an alternative, heat transfer fins may be present on the outer top and/or bottom surface, the heat transfer fins projecting from the respective outer top and/or bottom surface along a fin height, the fin height perpendicular to the respective outer top and/or bottom Area is measured with the minimum bend radius of the second bend being 0.70 to 0.95 times the rib height.

According to another preferred embodiment of the flat tube, the tube body defines numerous coolant passages arranged in a row along the width of the tube, with a partition between immediately adjacent coolant channels extending along the thickness of the tube body. Such a flat tube enables a particularly even distribution of heat exchange on its outer upper and lower surfaces. In addition, such flat tubes can have a particularly small thickness.

In another preferred embodiment of the flat tube, the tube body comprises or consists of a uniform material, the material preferably being metal. This improves heat transfer/exchange and allows a semi-finished flat tube to be bent to conform to the flat tube geometry of this embodiment of the invention.

According to another preferred embodiment of the flat tube, the bent portion has an S- or Z-like geometry in a view perpendicular to both the extension and offset directions. This means that if the first bend includes two sub-bends that together form an S- or Z-like shape, the second bend will continuously contribute to the S- or Z-like shape to achieve the S- or Z-like geometry of the to form curved section. As a result, the bending radius of the second bend can be increased.

The invention also relates to a heat exchanger comprising first flat tubes according to the invention as described above, with longitudinal ends of their angled portions facing away from their bent portions being received in associated second openings of a second header. Consequently, the above-mentioned advantages of the flat tube according to the invention carry over to the heat exchanger accordingly. In addition, the heat exchanger has second flat tubes, first longitudinal ends of these second flat tubes being received in associated third openings of a third header and second longitudinal ends of the second flat tubes, which are arranged opposite to their first longitudinal ends, in associated fourth openings of the first header be included. The first and fourth openings are spaced from each other.

According to a preferred embodiment of the heat exchanger, the first flat tubes and the second flat tubes are arranged alternately along a stacking direction that corresponds, in particular, is the same as the offset direction of the first flat tubes. A defrosting capacity can be increased by the alternating arrangement of the individual flat tubes. As a result, a defrosting cycle can be shortened and the overall energy efficiency of the heat exchanger can be increased.

In another preferred embodiment of the heat exchanger, there is a space between adjacent flat tubes in which heat transfer fins are housed. This improves the heat exchange/transfer between a fluid passing through the clearance and the coolant or refrigerant flowing through the flat tubes because the heat transfer fins effectively increase the heat transfer surface area of the heat exchanger.

Preferably, during assembly of the heat exchanger, the heat transfer fins are held in place by the first bend.

According to another preferred embodiment of the heat exchanger, in a view along the stacking direction, the heat exchanging portions of the first flat tubes completely overlap the second flat tubes, whereas the angled portions of the first flat tubes do not. This enables a particularly good heat exchange while keeping a profile of the heat exchanger and an air pressure drop low.

In another preferred embodiment of the heat exchanger, the second flat tubes are essentially straight. Such second flat tubes can easily be taken from inventory without any manufacturing or modification process being performed on them other than cutting to length.

According to another preferred embodiment of the heat exchanger, both the second flat tubes and the first flat tubes are in accordance with the invention as described above. Then, the transverse direction of the first flat tubes is different from that of the second flat tubes. Such a heat exchanger can be constructed in a particularly compact design.

Other important features and advantages of the invention will be apparent from the drawings and from the accompanying detailed description with the help of the drawings.

It should be understood that the features mentioned above and to be explained below can be used not only in the particular combination indicated, but also in other combinations or on their own, without departing from the scope of the present invention .

Preferred embodiments of the invention are shown in the drawings and will be explained in more detail in the following description, in which the same reference numbers refer to the same or similar or functionally the same components.

character list

• 1A zeigt ein Beispiel eines flachen Rohres nach der Erfindung in einer Ansicht gegen eine Querrichtung;
• 1B zeigt das Beispiel von 1A in einer Ansicht entlang einer Versetzungsrichtung;
• 2A zeigt ein anderes Beispiel eines flachen Rohres nach der Erfindung in einer Ansicht entlang der Versetzungsrichtung;
• 2B zeigt das Beispiel von 2A in einer Ansicht gegen die Querrichtung;
• 3A zeigt, teilweise, ein Beispiel eines Wärmetauschers nach der Erfindung in einer Ansicht gegen die Querrichtung;
• 3B zeigt ein erstes flaches Rohr des Wärmetauschers von 3A in einer Ansicht entlang der Versetzungsrichtung;
• 4A zeigt den Wärmetauscher von 3A in einer Draufsicht entlang der Versetzungsrichtung; und
• 4B zeigt ein anderes Beispiel des Wärmetauschers nach der Erfindung in einer Draufsicht entlang der Versetzungsrichtung.

It shows, in any case schematically:

• 1A shows an example of a flat tube according to the invention in a view against a transverse direction;
• 1B shows the example of 1A in a view along an offset direction;
• 2A Figure 12 shows another example of a flat tube according to the invention in a view along the offset direction;
• 2 B shows the example of 2A in a view against the transverse direction;
• 3A shows, in part, an example of a heat exchanger according to the invention in a view against the transverse direction;
• 3B shows a first flat tube of the heat exchanger of FIG 3A in a view along the offset direction;
• 4A shows the heat exchanger from 3A in a plan view along the offset direction; and
• 4B Figure 12 shows another example of the heat exchanger according to the invention in a plan view along the offset direction.

DETAILED DESCRIPTION OF THE DRAWINGS

1A shows an example of a flat tube 1 according to the invention in a view against a transverse direction 10, the flat tube 1 being configured to be used in a heat exchanger 30 according to FIG invention to be implemented, the latter in 3A , 4A and 4B is shown and will be described later. 1B shows the example of 1A in a view along an offset direction 12. As in FIG 1A and 1 B As can be seen, the flat tube 1 has a tube body 2 which delimits at least one coolant channel 3 through which a coolant or a refrigerant can flow. In the example of 1A the tube body 2 defines numerous coolant passages 3 arranged in a row along the width W of the tube 1 . A partition wall 17 extending along the thickness T of the tube body 2 is provided between two immediately adjacent coolant channels 3 . For example, the tubular body 2 has a uniform material or is made of such a uniform material. The material of the tubular body 2 is a metal, for example.

2A 1 illustrates another example of the flat tube 1 according to the invention in a view along the offset direction 12. 2 B shows the example of 2A in a view against the transverse direction 10. In other words, the perspective of 2A corresponds to that of 1 B , whereas the perspective of 2 B similar to that of 1A is. For the sake of clarity and better understanding, the coolant passages 3 of the tubular body 2 in the example of FIG 2A and 2 B Not shown.

How out 1A , 1B , 2A and 2 B As can be seen, the tubular body 2 has an outer upper surface 4 and an outer lower surface 5 which are arranged opposite to each other at a thickness T of the tubular body 2 . The tubular body 2 also has two outer side surfaces 6 which are arranged opposite one another at a width W of the tubular body 2 . The outer side surfaces 6 connect the outer upper and outer lower surfaces 4, 5. The tubular body 2 has a heat exchange section 7 which extends essentially along a direction 8 of extension. The tubular body 2 has an angled section 9 which extends essentially along a transverse direction 10 which is inclined in relation to the direction of extension 8 . The tubular body 2 has a bent section 11 which connects the heat exchange section 7 to the angled section 9 .

it's over 1A and 2 B it can be seen that the angled section 9 is located at a distance D from the heat exchange section 7, which distance D is to be measured in the offset direction 12. The offset direction 12 is substantially perpendicular to both the spanwise and transverse directions 8,10. The first bend 14 of the bent section 11 is bent against the offset direction 12 . In addition, the bent portion 11 has a second bend 16 present in a second end region 15 opposite the angled portion 9 . The second bend 16 is bent in the offset direction 12 . In other words, in the first end region 13 the tube body 2 is set back against the offset direction 12 due to the first bend 14 opposite to the heat exchange section 7 . Accordingly, in the second end portion 15, the tubular body 2 projects from the heat exchange portion 7 and from the first end portion 13 in the offset direction 12 due to the second bend 16. The curved section 11 has an S- or Z-like geometry 19, for example. Between the first bend 14 and the second bend 16, a step bend 22 (see 2A and 2 B) to be available. The first bend 14 may have an S- or Z-like shape consisting of two sub-bends, one directed against and one directed in the direction of offset, the two sub-bends together causing the tubular body 2 to oppose recedes to the offset direction 12 while moving away from the heat exchanging portion 7 in the extending direction 8 . When the first bend 14 includes two sub-bends that together have the S- or Z-like shape, the second bend 16 can continuously contribute to the S- or Z-like geometry to form the S- or Z-like geometry 19 of the bend Section 11 to form.

Also show 1A , 1B , 2A and 2 B that the extension direction 8 essentially follows a straight line. The transverse direction 10 is in the examples of FIG 1A , 1B , 2A and 2 B substantially perpendicular to the direction of extension 8. It goes without saying that as an alternative the transverse direction 10 as opposed to the right angle of 1A , 1B , 2A and 2 B can be inclined at a different angle with respect to the direction of extent 8 . The transverse direction 10 can follow a straight line or a curved line. The distance D at which the angled section 9 is arranged opposite the heat exchange section 7 is smaller than a minimum bend radius R of the second bend 16. The minimum bend radius R of the second bend 16 is, for example, 3 to 6 times the tube thickness T of the pipe body 2. The minimum bending radius R can be 0.70 to 0.95 times the pipe width W. The minimum bending radius R can be determined by an inner height H of the bent portion 11 that measured along the offset direction 12. As it progressively moves away from the heat exchange section 7, the bent section 11 is first set back by the first bend 14 against the offset direction 12, after which the bent section 11 begins to rise through its second bend 16 in the offset direction 12 to cross a plane, containing the heat exchange section 7, and finally merging in the offset direction 12 into the angled section 9.

To 1A , 1B , 2A and 2 B the second bend 16 is a twist bend 18. This means that the tube body 2 is bent and twisted in the second bend 16 at the same time, so that on the one hand the distance between the angled section 9 and the heat exchange section 7 is bridged and on the other hand the exact same surface of the tube body 2, which is the upper surface 4 in the heat exchanging section 7, is changed to the lower surface 5 in the area of the bent section 9. Consequently, the tubular body 2 can be rotated through 180° in the second bend 16 .

As mentioned above, the flat tube 1 can be used in a heat exchanger 30 according to the invention. In 3A an example of the heat exchanger 30 according to the invention is partially shown in a view against the transverse direction 10 . The heat exchanger 30 comprises first flat tubes 1 according to the invention, one of which is separately in 3B is illustrated in a view along the offset direction 12 . Alternatively, the first flat tube 1 of the heat exchanger 30 can be the examples of FIG 1A , 1B , 2A and 2 B , as described above. The first flat tubes 1 of the heat exchanger 30 each have a first longitudinal end 20 of their heat exchange sections 7 pointing away from their bent sections 11 .

4A 12 shows the heat exchanger 30 in a plan view along the offset direction 12. As in FIG 3A and 4A As can be seen, the first longitudinal ends 20 of the first flat tubes 1 are received in associated first openings 39 of a first header 36 of the heat exchanger 30 . Each of the first flat tubes 1 also has a second longitudinal end 21 of its angled portions 9 pointing away from its bent portion 11 . These second longitudinal ends 21 are received in associated second openings 40 of a second header 37 of the heat exchanger 30 . The heat exchanger 30 also has second flat tubes 31 . These second flat tubes 31 have first longitudinal ends 32 which are received in associated third openings 41 of a third header 38 of the heat exchanger 30 . The second flat tubes 31 also have second longitudinal ends 33 disposed opposite their first longitudinal ends 32 and are received in associated fourth openings 42 of the first header 36 of the heat exchanger 30 . The first and fourth openings 39 and 42 are spaced from each other.

How out 3A As can be seen, heat transfer fins 34 may be present on the outer top and bottom surfaces 4, 5, with the heat transfer fins 34 projecting from the respective outer top and bottom surfaces 4, 5 along a fin height HF. The rib height HF is measured perpendicular to the outer top and bottom surfaces 4, 5, respectively. The minimum bending radius R of the second bend 16 is 0.70 to 0.95 times the rib height HF.

To 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, this stacking direction is the same as the offset direction 12 of the first flat tubes 1. Between two adjacent flat tubes 1, 31 in the heat exchanger 30 there may be a gap 35 in which the heat transfer fins 34 of the heat exchanger 30 are accommodated. For example, in a view along the stacking direction, the heat exchanging portions 7 of the first flat tubes 1 completely overlap the second flat tubes 31 , whereas the angled portions 9 of the first flat tubes 1 at least partially do not overlap the second flat tubes 31 . For example, the second flat tubes 31 may be substantially straight. For example, during assembling of the heat exchanger 30, the heat transfer fins 34 are held in place by the first bends 14 of the first flat tubes 1.

In an alternative example of the heat exchanger, which - in a plan view along the offset direction 12 - in 4B as an example, the second flat tubes 31 are configured to substantially correspond to the flat tube 1 of the invention as exemplified in FIG 1A , 1B , 2A and 2 B shown and described above, while the transverse direction 10 of the first flat tubes 1 differs from the transverse direction 10' of the second flat tubes 31. Consequently, both the first and second flat tubes 1 and 31 in the heat exchanger 30 can correspond to the flat tube 1 according to the invention, being mounted in the heat exchanger 30 in different, in particular mirrored, orientations. In the example of 4B are the first and second flat tubes 1 and 31 are formed as identical parts differing only in their orientation in the heat exchanger 30.

While the above description represents the preferred embodiments of the present invention, the invention is susceptible to modification, variation and change without departing from the true scope and fair meaning of the appended claims.

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• CN 103644685A [0003]

Claims (15)

Flat tube (1) for a heat exchanger (30), which comprises a tube body (2) which delimits at least one coolant channel (3) for a coolant or refrigerant, the tubular body having an outer upper surface (4) and an outer lower surface (5) which are opposite to each other at a thickness (T) of the tubular body (2), and two outer side surfaces (6) which are opposite to each other at a Width (W) of the tubular body (2) are arranged, wherein the outer side surfaces (6) connect the outer upper with the outer lower (4, 5) surface, wherein the tubular body (2) has a heat exchange section (7) which extends along a direction of extent (8), the tubular body (2) having an angled portion (9) extending along a transverse direction (10) which is inclined with respect to the direction of extension (8), wherein the tubular body (2) has a bent portion (11) connecting the heat exchange portion (7) to the angled portion (9), the angled section (9) being located at a distance (D) from the heat exchange section (7) measured in an offset direction (12) perpendicular to both the spanwise and transverse directions (8, 10), the bent portion (11) having a first end portion (13) facing the heat exchange portion (7) with a first bend (14) against the offset direction (12) and a second end portion (15) facing the angled portion (9) opposite, with a second bend (16) in the offset direction (12). Flat tube (1) after claim 1 wherein the second bend (16) is a twist bend (18). Flat tube (1) after claim 1 , wherein the extension direction (8) follows a straight line. Flat tube (1) after claim 1 , wherein the transverse direction (10) is perpendicular to the direction of extension (8). Flat tube (1) after claim 1 , wherein the distance (D) at which the angled portion (9) is located opposite to the heat exchange portion (7) is smaller than a minimum bend radius (R) of the second bend (16). Flat tube (1) after claim 5 , wherein the minimum bend radius (R) of the second bend (16) is 3 to 6 times the tube thickness (T). Flat tube (1) after claim 1 , wherein the tube body (2) defines numerous coolant channels (3) arranged in a row along the width (W) of the tube (1), immediately adjacent coolant channels (3) being separated by a partition (17) which along the thickness (T) of the tubular body (2). Flat tube (1) after claim 1 , wherein the pipe body (2) comprises a uniform metal material. Flat tube (1) after claim 1 wherein the bent portion (11) has an S- or Z-like geometry (19) in a view perpendicular to both the extension and offset directions (8, 12). Heat exchanger (30) comprising: First flat tubes (1) according to one of the preceding claims, wherein first longitudinal ends (20) of their heat exchanger sections (7) facing away from their bends (11) in associated first openings of a first collector and second longitudinal ends (21) of their heat exchanger sections (7) facing away from their bends (11). bends (9) are accommodated in associated second openings of a second collector, second flat tubes (31), first longitudinal ends (32) of the second flat tubes (31) in associated third openings of a third collector and second longitudinal ends (33) of the second flat tubes (31), which are arranged opposite their first longitudinal ends (32), in associated fourth openings of the second collector are included, wherein the second and fourth openings are spaced from each other. Heat exchanger (30) after claim 10 wherein the first flat tubes (1) and the second flat tubes (31) are arranged alternately along a stacking direction corresponding to the offset direction (12) of the first flat tubes (1). Heat exchanger (30) after claim 11 wherein, in a view along the stacking direction, the heat exchange portions (7) of the first flat tubes (1) completely overlap the second flat tubes (31), whereas the angled portions (9) of the first flat tubes (1) do not. Heat exchanger (30) after claim 10 wherein between adjacent flat tubes (1, 31) there is a space (35) in which heat transfer fins (34) are housed. Heat exchanger (30) after claim 10 , wherein the second flat tubes (31) are straight. Heat exchanger (30) according to one of Claims 10 until 13 , wherein the second flat tubes one of Claims 1 until 9 correspond, - wherein the transverse direction (10) of the first flat tubes (1) differs from that of the second flat tubes.

Images