Tube for heat exchanger

Abstract

The object of the invention is, inter alia, a tube (10) for a heat exchanger (1), comprising: a first tubular element (11) and at least one second tubular element (12), each tubular element (11, 12) comprising two juxtaposed longer walls (13) having a substantially flat surface connected by a pair of shorter walls (14) to form a closed profile of each tubular element (11, 12), the tube (10) further comprises at least one counter element (15) configured to fluidly connect the first tubular element (11) and the second tubular element (12), where the tubular elements (11, 12) are arranged adjacent to each other such that the respective longer walls (13) are coplanar relative to each other, where the counter element (15) is made integral with the tubular elements (11, 12).

Description

Technical Field

[0001] The present invention relates to a tube for a heat exchanger. In particular, the present invention relates to a tube for a heat exchanger of a motor vehicle. Background Art

[0002] The present invention relates to the field of heat exchangers, in particular heat exchangers with a typically high temperature difference between the inlet and outlet refrigerant temperatures. These heat exchangers are in particular condensers, gas coolers (where the temperature gradient is particularly high), but the present invention is possible and also beneficial for evaporators.

[0003] Known fluid refrigerant circuits form a closed loop in which a refrigerant fluid flows in order to dissipate or collect heat through a heat exchanger. The heat exchanger comprises a manifold connecting the heat exchanger to the fluid refrigerant circuit, the manifold connecting pipes from the fluid refrigerant circuit to the heat exchanger core so that the refrigerant fluid flows through the heat exchanger tubes.

[0004] In a circuit using R1234yf or R134a refrigerants (condensers), the refrigerant fluid passes through the fluid refrigerant circuit which can be gaseous, mixed and liquid. The working pressure in the condenser is up to 20 bar, and the burst pressure is justified by the application of a safety factor of 100 bar. For the working fluid R744 (gas cooler) the main supercritical gaseous fluid is used. The working pressure is about 100 bar, but it can also reach 170 bar. A burst pressure with a safety factor of 2 may be required, in which case the burst pressure is 340 bar.

[0005] Known heat exchangers include manifolds and heat exchange tubes that allow refrigerant fluid to migrate between the manifolds. The heat exchange tubes also allow heat exchange between the refrigerant fluid flowing within the heat exchange tubes and the air flowing outside the heat exchanger, thereby capturing heat from the air flowing through the heat exchanger core in the case of an evaporator and dissipating heat in the case of a condenser and a gas cooler.

[0006] The manifold includes a box, a header plate, and a distribution plate located between the box and the header plate. The box plate of the manifold is configured to define the manifold. The header plate of the manifold is designed to allow the refrigerant fluid to flow between the first manifold or the second manifold and the heat exchange tubes. The distribution plate is intended to allow the refrigerant fluid to flow between the connector connected to the distribution plate and the header plate.

[0007] The box plate, distribution plate and header plate are brazed together to ensure the sealing of the manifold and prevent leakage of refrigerant fluid. The header plate includes teeth configured to secure the assembly of the header plate, distribution plate and box plate together to help the brazed manifold withstand the very high pressures generated in the fluid refrigeration circuit.

[0008] In known heat exchangers, the tubes are arranged in a stack, or two stacks arranged next to each other. The individual tubes are located in the corresponding manifolds, and they are not in direct contact with each other. This brings many disadvantages starting from the assembly process of the heat exchanger. It is difficult to introduce the individual tubes into the tight grooves in the manifold. In addition, since there is no interaction between the tubes forming the stack, the stack of tubes itself is not strong. Therefore, during thermal expansion of the heat exchanger, for example, the individual tubes are prone to damage. In addition, the realization of many tubes arranged in a stack requires at least one manifold on each side of the open end of the tube. This can be solved by bending the tube into a U-turn. However, bending the tube itself is very difficult because it reduces its robustness. In addition, the tube is usually bent so that one side wall forms a tight turn of the U-turn, while the other side wall forms a wide turn of the U-turn. This will not only cause leakage, but also have a negative impact on the fluid flow in each tube. Therefore, this will also have a negative impact on the overall efficiency of the heat exchanger.

[0009] Furthermore, the efficiency of the heat exchanger is limited due to two factors in particular. First, the heat exchanger is not (in the case of one stack) or only partially (in the case of two stacks) countercurrent. In the case of adding one or more additional tube stacks, the countercurrent effect will increase, which brings the refrigerant outlet temperature closer to the air outlet temperature, with the result that the efficiency increases. The second factor is the compartments (or zones) with different temperatures, which is due to the refrigerant temperature changes caused by the interaction of the refrigerant with the air. If such a temperature gradient occurs, internal heat exchange occurs in these compartments due to heat conduction, with the result that the heat exchange between the refrigerant and the air is reduced. As a result, the efficiency of the heat exchanger can be reduced again.

[0010] The above-mentioned tube can be improved so as to increase the robustness of the tube and facilitate the assembly process of the heat exchanger. In addition, the overall cost of the tube and / or the heat exchanger can be easily reduced without affecting the performance of the heat exchanger. Summary of the invention

[0011] The object of the invention is in particular a tube for a heat exchanger, comprising: a first tubular element and at least one second tubular element, each tubular element comprising two juxtaposed longer walls having substantially flat surfaces connected by a pair of shorter walls to form a closed profile of each tubular element, wherein the tube further comprises at least one reverse element configured to fluidically connect the first tubular element and the second tubular element, wherein the tubular elements are arranged adjacent to each other such that the respective longer walls are coplanar with respect to each other, wherein the reverse element is made integral with the tubular elements.

[0012] Advantageously, the reverse element comprises a first twisted section and at least one second twisted section, wherein the first twisted section projects directly from the first tubular element and the second twisted section projects directly from the second tubular element.

[0013] Advantageously, the reverse element comprises a substantially U-shaped section configured to fluidly connect the first twisted section and the second twisted section.

[0014] Advantageously, the inverting element comprises a substantially straight section configured to fluidly connect the first twisted section and the second twisted section.

[0015] Advantageously, the second twisted section protrudes helically in one direction, wherein the first twisted section protrudes helically in the same direction as the second twisted section.

[0016] Advantageously, the second twisted section protrudes helically in one direction, wherein the first twisted section protrudes helically in a direction different from that of the second twisted section.

[0017] Advantageously, the first tubular element forms a first passage for the fluid and the second tubular element comprises a second passage for the fluid, wherein the intended direction of fluid flow in the second passage is counter-current with respect to the intended direction of fluid flow in the first passage.

[0018] Advantageously, the reversing section comprises substantially the same hydraulic cross-section as either the first tubular element or the second tubular element.

[0019] Advantageously, the tube is an extruded tube comprising a plurality of microchannels.

[0020] Advantageously, the heat exchanger further comprises at least one first manifold group configured to receive one end of the tubes, and a second manifold group configured to receive the other end of the tubes, wherein the first manifold group comprises at least a first channel in fluid connection with the first tubular element, thereby providing fluid communication between the at least two tube bundles, and the second manifold group comprises a second channel in fluid connection with at least the second tubular element, wherein the manifold groups are arranged adjacent to each other.

[0021] Advantageously, the first manifold set and the second manifold set comprise a header plate comprising slots for receiving the tubes, a distributor plate configured to form the first channel and the second channel in the manifold set, and a box plate for closing the manifold set.

[0022] Advantageously, the header plate comprises a plurality of teeth configured to secure the distributor plate and the box plate.

[0023] Advantageously, the tube further comprises a third tubular element and a fourth tubular element, wherein the third tubular element and the fourth tubular element are fluidically connected by respective reverse elements.

[0024] The reverse element allows the intended flow direction of the fluid to be changed without the need to provide an additional manifold. It can significantly reduce the overall cost and weight of the heat exchanger while maintaining the required packaging. Unlike tubes that include a straight U-turn, the reverse element with a twisted section also allows a substantially equidistant path to be formed for the fluid throughout the tube, where the side walls have different lengths at a certain point. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Examples of the present invention will become apparent and described in detail with reference to the accompanying drawings, in which:

[0026] Figure 1 A partial side view of a tube with an inverted section is shown.

[0027] Figure 2 A side view of a tube having at least two different types of inverted sections is shown.

[0028] Figure 3 A detailed view of the reverse section in one of the examples is shown.

[0029] Figure 4 A detailed view of another reverse section in one of the examples is shown.

[0030] Figure 5 Shows at least one Figure 1-4 A perspective view of a tube heat exchanger is shown.

[0031] Figure 6 A side view of a tube-manifold assembly in one example is shown. DETAILED DESCRIPTION

[0032] The subject of the invention is a tube 10 for a heat exchanger 1 suitable for the exchange of heat between a first fluid and a second fluid. The first fluid may be, for example, a pressurized refrigerant, such as carbon dioxide, circulating inside the heat exchanger 1, while the second fluid may be, for example, air. The heat exchanger 1 is intended to reduce the temperature of the first fluid. It may thus be associated with a gas cooler, an internal gas cooler, an evaporator, etc. The other paragraphs discuss the main components of the tube 10 suitable for implementation in such a heat exchanger, as well as its mechanical or structural features which ensure an improvement in efficiency with respect to known heat exchangers.

[0033] Figure 1 A partial side view of a tube 10 for a heat exchanger 1 is shown. The term "tube" is not limited to a straight piece of tubular element having two open ends. Here, the term "tube" means that there may be more than one tubular element suitable for fluid transport, and the tubular elements are at least partially integrated to form a subassembly. The partial view does not show the open end of the tube 10, because it is intended to show other features in more detail.

[0034] refer to Figure 1 and Figure 2 , the tube 10 may include a first tubular element 11 and at least one second tubular element 12. Figure 2 As shown, it is also envisioned that an embodiment of introducing more tubular elements, i.e., the third tubular element 30 and the fourth tubular element 40, is introduced. It should be noted that there is no limit to the number of tubular elements implemented. The third tubular element 30 and the fourth tubular element 40 are substantially the same as the first tubular element 11 and the second tubular element 12, but they have different reference numerals throughout the description to avoid confusion among readers. Each tubular element 11, 12, 30, 40 may include two juxtaposed longer walls 13, and the longer walls 13 have a substantially flat surface. In other words, the longer walls 13 are substantially identical wall portions arranged in parallel, and face each other with their respective flat surfaces. The tubular element 11, 12, 30, 40 may also include two shorter walls 14 connecting the longer walls 13 to form a closed profile, and an elongated axis. The tube 10 may also include two open ends 19. The term open end refers to the terminal of the tubular element 11, 12, 30, 40, which allows fluid to enter or leave the entire tube 10.

[0035] The open ends 19 of the tube 10 are arranged on the same side and at the same level, while the longer walls 13 of adjacent tubular elements 11, 12 are arranged so that their flat surfaces are coplanar relative to each other. In order to achieve this configuration, the tube 10 may further include at least one reverse element 15, which is configured to fluidically connect the first tubular element 11 and the second tubular element 12. The reverse element 15 can be made integrally with the two tubular elements 11, 12. In other words, the reverse element 15 is made in the process of bending the pipe, providing a reverse flow of the fluid in its integral piece. Alternatively, the reverse element 15 can be a separate element fixed to the two tubular elements 11, 12. However, this embodiment is not preferred because the durability of such an assembly is poor compared to an integral assembly.

[0036] The reversing element 15 may thus be interpreted as any integral section of the tube 10 configured to alter the intended flow of the fluid within the tube 10. In particular, the reversing element 15 may be configured to provide a reverse flow of the fluid within two adjacent straight sections of the tube 10 (i.e., the first tubular element 11 and the second tubular element 12, etc.).

[0037] refer to Figure 3 and Figure 4, the reverse element 15 may in particular include a first twisted section 15A and at least one second twisted section 15B. The term "twisted" means that the sections are substantially spiral or semi-spiral. The twisted sections 15A, 15B allow the fluid channel to transition more smoothly without abruptly changing the hydraulic diameter within the reverse element 15. In addition, if the tube 10 is an extruded tube including microchannels, the channels maintain their desired shape.

[0038] The integrity between the tubular elements 11, 12, 30, 40 and the reverse element 15 can be described so that the first twisted section 15A can protrude directly from the first tubular element 11 and the second twisted section 15B can protrude directly from the second tubular element 12. The twisted sections 15A, 15B can then be connected together to form fluid communication between adjacent tubular elements 11, 12, 30, 40. Of course, the second twisted section 15B can also protrude directly from the first twisted section 15A, so other ways of describing the twisted sections 15A, 15B are also possible. This mainly depends on the reference point. For example, the first twisted section 15A can protrude in a spiral manner in a counterclockwise direction relative to the first tubular element 11, while the first twisted section 15A can protrude in a clockwise direction relative to the second twisted section 15B. Similarly, the second twisted section 15B may helically protrude in a counterclockwise direction relative to the second tubular element 12 , while the second twisted section 15B may protrude in a clockwise direction relative to the first twisted section 15B.

[0039] The reverse element may include a substantially U-shaped section 16A connecting the first twisted section 15A and the second twisted section 15B. The U-shaped section 16A may have a relatively small curvature, or a large curvature. The small curvature of the U-shaped section is formed to the extent permitted by the mechanical properties of the material from which the tube 10 is made. The small curvature allows the continuous tubular elements 11, 12, 30, 40 to be packed closer to each other, thereby improving packaging. On the other hand, the large curvature is conducive to the thermal decoupling of the continuous tubular elements 11, 12, 30, 40, and allows the fluid therein to be transmitted relatively more smoothly.

[0040] The reverse element 15 may also include a substantially straight section 16B. Similar to the U-shaped section 16A, the straight section 16B may be configured to fluidically connect the first twisted section 15A and the second twisted section 15B between the tubular elements 11, 12, 30, 40. As described in the previous paragraph, the second twisted section 15B spirally protrudes in one direction, wherein the first twisted section 15A spirally protrudes in the same direction as the second twisted section 15B. Alternatively, the second twisted section 15B spirally protrudes in one direction, wherein the first twisted section 15A spirally protrudes in a direction different from the second twisted section 15B. The spiral direction of the protrusion means that the side walls 14 remain substantially equidistant relative to each other, but the elongation axes of the tubular elements 11, 12, 30, 40 are disordered.

[0041] The reverse element 15 allows the intended flow direction of the fluid to be changed without the need to provide an additional manifold. It can significantly reduce the overall cost and weight of the heat exchanger 1 while maintaining the desired packaging. The reverse element 15 with twisted sections 15A, 15B also allows a substantially equidistant path to be formed for the fluid throughout the tube 10, unlike a tube including a straight U-turn, where the sidewall 14 has different lengths at a certain point.

[0042] Each tube 10, including the tubular elements 11, 12, 30, 40 and the reverse element 15, may include a set of microchannels extending between the open ends of the tube 10. Of course, the microchannels are continuous throughout the reverse element 15, i.e., the microchannels in the reverse element are configured to fluidically connect the corresponding microchannels in the corresponding tubular elements 11, 12, 30, 40. The tubular elements 11, 12, 30, 40 may have the same dimensions, i.e., their outer dimensions, such as: width, measured as the distance between the outer surfaces of the shorter walls 14; length, measured along the longer walls 13 as the distance between the open ends of the tube; or height, measured as the distance between the outer surfaces of the longer walls of the same tubular element 11, 12, 30, 40.

[0043] The tube 10 may be implemented in a heat exchanger 1. The heat exchanger 1 may comprise in particular a plurality of tubes 10 arranged in a stacking direction, wherein the stacking direction is perpendicular to the planar surfaces of the tubes 11, 12, 30, 40.

[0044] The heat exchanger 1 may further include at least one first manifold group 100 and at least one second manifold group 200. The first manifold group 100 may be configured to accommodate one open end of the tube 10, and the second manifold group 200 may be configured to accommodate the other open end of the tube 10. Since the open ends of the tubes 10 may be arranged adjacent to each other, the tubes 10 may be connected to a single common manifold group, such as the first manifold group 100, so that the first manifold group includes at least two separate channels for the fluid. In other embodiments not shown in the figures, the heat exchanger 1 may also include a first group including the tubes 10 and a second group including a plurality of separate tubes arranged in a stacked manner. The term separate tube refers to a tube having a substantially straight structure with two opposite open ends. In this embodiment, the heat exchanger 1 may include a third manifold group to provide a U-turn for the fluid so that the fluid can flow between the stack of separate tubes.

[0045] The first manifold set 100 may include at least a first passage 101 in fluid connection with the first tubular element 11, thereby providing fluid communication between at least two tubes 10. The second manifold set 200 may include a second passage 202 in fluid communication with at least two second tubular elements 12 or any tubular element 30, 40, which should be considered the last in the series.

[0046] Figure 5 and 6 A heat exchanger 1 is shown, wherein the tube bundle 10 further comprises a first tubular element 11, a second tubular element 12, a third tubular element 30 and a fourth tubular element 40, wherein the first tubular element 11 forms a first passage P1 for a fluid, the second tubular element 12 forms a second passage P2 for a fluid, wherein the reverse element 15 fluidly connects the passages, the third tubular element 30 forms a third passage P3 for a fluid, and the fourth tubular element 40 forms a fourth passage P4 for a fluid, wherein one reverse element 15 fluidly connects the second passage P2 and the third passage P3, and another reverse element fluidly connects the third passage P3 and the fourth passage P4. The term passage refers to the intended direction of movement of the fluid in the passage in the same sense. A heat exchanger 1 comprising four passages as arranged in the present invention allows for better heat removal, increased heat transfer and overall increased heat exchanger performance, while maintaining a relatively small package.

[0047] from Figure 6 As can be clearly seen in the figure, at least one reverse element 15 can be located between the first manifold set 100 and the second manifold set 200. Furthermore, the reverse element 15 can be substantially at the same level as the manifold sets 100, 200. Alternatively, at least one reverse element 15 can protrude beyond the level of the manifold sets 100, 200, such that at least a portion of the reverse element protrudes beyond the level of the teeth 160.

[0048] The term "manifold group" may refer to one or more manifolds arranged adjacent to each other. For example, a "first manifold group" may refer to two manifolds arranged adjacent to each other, wherein the manifolds share the same structural features.

[0049] The first manifold group 100 and the second manifold group 200 may include: a collecting plate 100a, 200a, which includes a groove 150 for accommodating the open end of each tubular element 11, 40; a distribution plate 100b, 200b, which is configured to transmit fluid between the tube 10 and the channel; and a box plate 100c, 200c, which is configured to form a first channel 101 and a second channel 202 in the manifold group 100, 200.

[0050] refer to Figure 6 Since the manifold sets 100, 200 may be manufactured by crimping and brazing the following components, they may include a plurality of teeth 160 configured to fix the distribution plates 100b, 200b and the box plates 100c, 200c to the header plates 100a, 200a.

[0051] The heat exchanger 1 may comprise an inlet and an outlet for the first fluid. Both the inlet and the outlet may be in the form of openings of corresponding pipes which are fluidically connected to the refrigerant circuit. Figure 5 As shown, the openings may also be connected indirectly, for example by a connection block or other type of connector. Depending on the desired flow pattern or the location of the inlet and outlet, the pipes or connection blocks may be fixed in any suitable place.

[0052] Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, by studying the drawings, the disclosure, and the appended claims.The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Claims

1. A tube (10) for a heat exchanger (1), comprising: A first tubular element (11) and at least one second tubular element (12), each tubular element (11, 12) comprising two juxtaposed longer walls (13) having substantially flat surfaces connected by a pair of shorter walls (14) to form a closed profile of each tubular element (11, 12), wherein the tube (10) further comprises at least one reverse element (15), the reverse element (15) being configured to fluidically connect the first tubular element (11) and the second tubular element (12), wherein the tubular elements (11, 12) are arranged adjacent to each other such that the respective longer walls (13) are coplanar with respect to each other, wherein the reverse element (15) is made integrally with the tubular elements (11, 12).

2. A tube (10) according to any one of the preceding claims, wherein The reverse element (15) comprises a first twisted section (15A) and at least one second twisted section (15B), wherein the first twisted section (15A) directly protrudes from the first tubular element (11) and the second twisted section (15B) directly protrudes from the second tubular element (12).

3. The tube (10) according to claim 2, wherein: The reverse element (15) includes a substantially U-shaped section (16A) configured to fluidly connect the first twisted section (15A) and the second twisted section (15B).

4. The tube (10) according to claim 2, wherein: The reverse element (15) includes a substantially straight section (16B) configured to fluidly connect the first twisted section (15A) and the second twisted section (15B).

5. The tube (10) according to any one of claims 2 to 4, wherein The second twisted section (15B) spirally protrudes in one direction, wherein the first twisted section (15A) spirally protrudes in the same direction as the second twisted section (15B).

6. A tube (10) according to any one of claims 2 to 4, wherein: The second twisted section (15B) spirally projects in one direction, wherein the first twisted section (15A) spirally projects in a direction different from that of the second twisted section (15B).

7. A tube (10) according to any one of the preceding claims, wherein The first tubular element (11) forms a first passage (P1) for fluid, and the second tubular element (12) includes a second passage (P2) for fluid, wherein the intended fluid flow direction in the second passage (P2) is countercurrent relative to the intended fluid flow direction in the first passage (P1).

8. A tube (10) according to any one of the preceding claims, wherein The reversing section (15) comprises substantially the same hydraulic cross-section as either the first tubular element (11) or the second tubular element (12).

9. A tube (10) according to any one of the preceding claims, wherein The tube (10) is an extruded tube comprising a plurality of microchannels.

10. A heat exchanger (1) comprising at least one tube (10) according to claim 1, wherein: The heat exchanger (1) further comprises: at least one first manifold group (100), the first manifold group (100) being configured to accommodate one end of the tube (10), and a second manifold group (200), the second manifold group (200) being configured to accommodate the other end of the tube bundle (10), characterized in that the first manifold group (100) comprises at least a first channel (101) fluidically connected to the first tubular element (11), thereby providing fluid communication between at least two tube bundles (10), and in that the second manifold group (200) comprises a second channel (202) fluidically connected to at least a second tubular element (12), wherein the manifold groups (100, 200) are arranged adjacent to each other.

11. The heat exchanger (1) according to any one of claims 10 to 12, wherein: The first manifold group (100) and the second manifold group (200) include: a collecting plate (100a, 200a), the collecting plate (100a, 200a) including a groove (150) for accommodating the tubes (11, 12, 30, 40); a distribution plate (100b, 200b), the distribution plate (100b, 200b) is configured to form the first channel (101) and the second channel (102) in the manifold group (100, 200); and a box plate (100c, 200c) for closing the manifold group (100, 200).

12. The heat exchanger (1) according to claim 12, wherein: The header plate (100a, 200a) includes a plurality of teeth (160) configured to fix the distribution plate (100b, 200b) and the box plate (100c, 200c).

13. A heat exchanger (1) according to any one of the preceding claims, wherein: The tube (10) further comprises a third tubular element (30) and a fourth tubular element (40), wherein the third tubular element (30) and the fourth tubular element (40) are fluidically connected via respective reverse elements (15).

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