Microchannel flat tube and vehicle air conditioning condenser

Abstract

The present application relates to the technical field of vehicle air conditioning, and in particular to a microchannel flat tube and a vehicle air conditioning condenser. The microchannel flat tube includes a flat tube body, which is formed with a heat exchange channel; the flat tube body has a cross section perpendicular to its length direction, and the heat exchange channel forms a cross section on the cross section of the flat tube body, which is also the cross section of the heat exchange channel; by changing the shape of the cross section of the heat exchange channel, when the cross-sectional area of ​​the heat exchange channel remains unchanged, the heat exchange channel can have different hydraulic diameters, so that the heat exchange channel can have a smaller hydraulic diameter by analyzing the cross-sectional shape of the heat exchange channel, thereby making the heat exchange channel and the flat tube body have better heat exchange performance.

Description

Technical Field

[0001] The present application relates to the technical field of vehicle air conditioning, and in particular to a microchannel flat tube and a vehicle air conditioning condenser. Background Art

[0002] Existing automotive air-conditioning condensers usually use microchannel flat tubes as the pipe parts of the condenser. A heat exchange channel for dissipating heat from the refrigerant is formed inside the microchannel flat tube. Increasing the heat exchange area of ​​the refrigerant heat exchange is the most direct way to improve the heat dissipation performance of the condenser, and one of the ways to increase the heat exchange area is to reduce the hydraulic radius of the heat exchange channel. In the current condensers, most use internal multi-microchannel flat tubes, that is, multiple heat exchange channels are formed inside the microchannel flat tube, and the multiple heat exchange channels are arranged side by side in the same direction; but the cross-section of the previous heat exchange channel is mostly rectangular or circular (including elliptical). For a single heat exchange channel, although the circular or elliptical heat exchange channel has a smaller hydraulic radius, the material consumption is large and uneconomical; therefore, most microchannel flat tubes use a heat exchange channel with a rectangular cross-section, but the shape of its single hole is closer to a square, the hydraulic radius is larger, and the heat exchange performance is poor. Summary of the invention

[0003] The purpose of the present application is to provide a microchannel flat tube and a vehicle air-conditioning condenser to improve the heat dissipation efficiency of the microchannel flat tube.

[0004] The present invention provides a microchannel flat tube, comprising a flat tube body; the flat tube body is formed with a heat exchange channel, the heat exchange channel extends along the length direction of the flat tube body, and the heat exchange channel is used to allow refrigerant to circulate in the flat tube body; the heat exchange channel forms a section on the cross section of the flat tube body, and when the cross-sectional area of ​​the section remains unchanged, the shape change of the section can enable the heat exchange channel to have different hydraulic diameters.

[0005] Furthermore, the cross-section of the heat exchange channel on the cross section of the flat tube body is a rectangular hole; the rectangular hole includes a first straight side and a second straight side, the first straight side is parallel to the thickness direction of the flat tube body, and the second straight side is parallel to the width direction of the flat tube body; the length of the first straight side is H, and the length of the second straight side is W.

[0006] Furthermore, a length ratio of the first straight side to the second straight side is H / W≤0.5 or H / W≥2.

[0007] Furthermore, a length ratio of the first straight side to the second straight side is 2≤H / W≤3.

[0008] Furthermore, there are multiple heat exchange channels, and the multiple heat exchange channels are spaced apart and distributed along the width direction of the flat tube body; a partition rib is formed between any two adjacent heat exchange channels, and the thickness of the partition rib is S.

[0009] Furthermore, the thickness of the partition rib is 0.1 mm ≤ S ≤ 0.18 mm.

[0010] Furthermore, the thickness of the ribs is S=(0.15±0.03) mm.

[0011] Furthermore, the thickness of the flat tube body is T, and the thickness of the flat tube body is T=1.3-1.5 mm.

[0012] Furthermore, the thickness of the flat tube body is T=1.5 mm, the length of the first straight side is H=1.26 mm, the length of the second straight side is W=0.573 mm, and the thickness of the rib is S=0.15 mm.

[0013] The present invention also provides a vehicle air-conditioning condenser, comprising any of the above-mentioned microchannel flat tubes.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] The microchannel flat tube provided by the present invention includes a flat tube body, and the flat tube body is formed with a heat exchange channel. The flat tube body has a cross section perpendicular to its length direction, and the heat exchange channel forms a cross section on the cross section of the flat tube body, which is also the cross section of the heat exchange channel; the cross section of the heat exchange channel can be elliptical (including circular) or rectangular (including square); changing the shape of the cross section of the heat exchange channel includes making the cross section of the heat exchange channel elliptical or rectangular, or changing the outer dimensions of the ellipse or rectangle, such as the ratio of the major diameter to the minor diameter of the ellipse, the aspect ratio of the rectangle, etc., when the cross-sectional area of ​​the heat exchange channel remains unchanged, the heat exchange channel can have different hydraulic diameters, so that the heat exchange channel can have a smaller hydraulic diameter by analyzing the cross-sectional shape of the heat exchange channel, and then the heat exchange channel and the flat tube body have better heat exchange performance.

[0016] The present invention also provides a vehicle air-conditioning condenser, comprising the microchannel flat tube, so the vehicle air-conditioning condenser also has the beneficial effects of the microchannel flat tube. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 A schematic diagram of the arrangement of heat exchange channels with a square or nearly square cross section in a flat tube body provided in an embodiment of the present invention;

[0019] Figure 2 A schematic diagram of the arrangement of heat exchange channels with elliptical cross sections in a flat tube body provided in an embodiment of the present invention;

[0020] Figure 3 A H / W-hydraulic diameter relative ratio relationship diagram provided for an embodiment of the present invention;

[0021] Figure 4 A schematic diagram of the arrangement of heat exchange channels in a flat tube body when H / W≤0.5 provided in an embodiment of the present invention;

[0022] Figure 5 A schematic diagram of the arrangement of heat exchange channels in a flat tube body when H / W ≥ 2 provided in an embodiment of the present invention;

[0023] Figure 6 CAE analysis diagram of heat exchange performance of flat tube bodies with different hydraulic diameters provided by the embodiment of the present invention;

[0024] Figure 7 This is a CAE analysis diagram of the refrigerant side pressure drop in the flat tube body under different hydraulic diameters provided in an embodiment of the present invention.

[0025] Reference numerals:

[0026] 1-flat tube body, 2-heat exchange channel, 3-first straight edge, 4-second straight edge, 5-partition ribs. DETAILED DESCRIPTION

[0027] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments.

[0028] The components of the embodiments of the present invention generally described and shown in the drawings herein may be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention.

[0029] Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without making any creative work shall fall within the scope of protection of the present invention.

[0030] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0031] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0032] Refer to the following Figures 1 to 7 The present invention describes a microchannel flat tube and a vehicle air conditioning condenser according to some embodiments of the present application.

[0033] The present application provides a microchannel flat tube for a condenser of an automobile air conditioner; Figure 1 and Figure 2 As shown, the microchannel flat tube includes a flat tube body 1, and the flat tube body 1 is formed with a heat exchange channel 2. When the condenser is working, the high-temperature and high-pressure gaseous refrigerant from the automobile compressor enters the heat exchange channel 2 of the microchannel flat tube and exchanges heat with the external ambient air, so that the heat absorbed by the refrigerant in the vehicle is dissipated into the atmosphere; the refrigerant after heat dissipation changes from a high-temperature and high-pressure gaseous state to a low-temperature and low-pressure liquid state, and is then transported back to the vehicle's evaporator to cool the passenger compartment.

[0034] In this embodiment, preferably, the cross-section of the flat tube body 1 perpendicular to its length direction is a flat long oval, and the flat tube body 1 has a predetermined width and thickness in its cross-section. The length direction of the heat exchange channel 2 extends along the length direction of the flat tube body 1, and the number of heat exchange channels 2 is multiple, and the multiple heat exchange channels 2 are arranged side by side and spaced along the width direction of the flat tube body 1. The flat tube body 1 has a cross-section perpendicular to its length direction, and the heat exchange channel 2 forms a cross section on the cross-section of the flat tube body 1, which is also the cross-section of the heat exchange channel 2; the cross-section of the heat exchange channel 2 can be an oval (including a circle) or a rectangle (including a square); as Figure 1 The schematic diagram shows the arrangement of the heat exchange channel 2 with a square or nearly square cross section in the flat tube body 1. Figure 2 The schematic diagram of the arrangement of the heat exchange channel 2 with an elliptical cross section in the flat tube body 1 is shown. Changing the shape of the cross section of the heat exchange channel 2 includes making the cross section of the heat exchange channel 2 elliptical or rectangular, or changing the outer dimensions of the ellipse or rectangle, such as the ratio of the major diameter to the minor diameter of the ellipse, the aspect ratio of the rectangle, etc., can make the heat exchange channel 2 have different hydraulic diameters when the cross-sectional area of ​​the heat exchange channel 2 remains unchanged, so that the heat exchange channel 2 can have a smaller hydraulic diameter by analyzing the cross-sectional shape of the heat exchange channel 2, thereby making the heat exchange channel 2 and the flat tube body 1 have better heat exchange performance.

[0035] like Figure 1 and Figure 2 As shown, when the cross section of the heat exchange channel 2 is elliptical, although for a single heat exchange channel 2, the elliptical cross-sectional shape can make it have a smaller hydraulic diameter, thereby making the heat exchange channel 2 have a better heat exchange effect, but for a flat tube body 1 with a predetermined width and thickness, compared with the heat exchange channel 2 with a rectangular cross section, the elliptical heat exchange channel 2 not only has a low utilization rate of the inner wall space of the flat tube body 1, but also has a relatively small flow area, which affects the heat exchange efficiency of the flat tube body 1.

[0036] In this embodiment, preferably, the cross section of the heat exchange channel 2 is rectangular, that is, the cross section of the heat exchange channel 2 on the cross section of the flat tube body 1 is a rectangular hole (including Figure 1 The rectangular hole has a first straight side 3 and a second straight side 4 perpendicular to each other, wherein the first straight side 3 is parallel to the thickness direction of the flat tube body 1, and the length of the first straight side 3 is H, and the second straight side 4 is parallel to the width direction of the flat tube body 1, and the length of the second straight side 4 is W. Any two adjacent heat exchange channels 2 are separated by a partition rib 5 with a thickness of S. Preferably, a plurality of partition ribs 5 are formed in the flat tube body 1, and the plurality of partition ribs 5 are arranged relatively spaced along the width direction of the flat tube body 1, so that a heat exchange channel 2 with a rectangular hole cross section is formed between any two adjacent partition ribs 5. The internal space of the flat tube body 1 is divided into a plurality of heat exchange channels 2 by the partition ribs 5, so that the space of the flat tube body 1 can be fully utilized, so that the flat tube body 1 has a larger heat exchange area, so that the flat tube body 1 and the condenser have good heat dissipation performance.

[0037] It should be noted that the heat exchange channels 2 at both ends of the flat tube body 1 in the width direction are surrounded by the partition ribs 5 and the side walls of the flat tube body 1. Since the cross section of the flat tube body 1 is an oblong, the cross sections of the two heat exchange channels 2 at both ends of the flat tube body 1 in the width direction are not rectangular. The following is an analysis of the heat exchange channel 2 with a rectangular hole (including a square hole) in the cross section. Under the condition that the flow area of ​​the heat exchange channel 2 remains unchanged, how to make the heat exchange channel 2 have a smaller hydraulic diameter, thereby increasing the heat exchange area of ​​the heat exchange channel 2 and improving the heat dissipation performance of the flat tube body 1 and the condenser.

[0038] In one embodiment of the present application, preferably, a length ratio of the first straight side 3 to the second straight side 4 is H / W≤0.5 or H / W≥2.

[0039] In this embodiment, under the condition that the area of ​​the rectangular hole remains unchanged, the shape of the rectangular hole is different, that is, when the length ratio H / W of the first straight side 3 and the second straight side 4 of the rectangular hole is different, the perimeter of the rectangular hole is also different, and correspondingly, the hydraulic diameter and heat dissipation area of ​​the heat exchange channel 2 are also different. Taking different values ​​of H / W, the hydraulic diameter of the heat exchange channel 2 is calculated at different values ​​of H / W, such as H / W = 0.286, 0.333, 0.4, 0.5, 0.667, 0.8, 1, 1.25, 1.5, 2, 2.5, 3 and 3.5; and the ratio of the hydraulic diameter at different values ​​of H / W to the hydraulic diameter when H / W = 1 is calculated to obtain the relative ratio of the hydraulic diameter. Then, a graph is drawn with the H / W value as the horizontal coordinate and the hydraulic diameter relative ratio as the vertical coordinate, and we get: Figure 3 The parabola of the H / W-hydraulic diameter relative ratio is shown.

[0040] Depend on Figure 3 It can be seen that the relative ratio of hydraulic diameter reaches its peak value when H / W=1, that is, when the rectangular hole is a square, which means that when the cross section of the heat exchange channel 2 is a square, the hydraulic diameter is the largest, the heat exchange area of ​​the heat exchange channel 2 is the smallest, and the heat dissipation efficiency is the worst. When H / W>1, as H / W increases, the relative ratio of hydraulic diameter decreases, that is, the hydraulic diameter decreases continuously; similarly, when H / W<1, as H / W decreases, the hydraulic diameter also decreases continuously. Therefore, when the cross-sectional shape of the heat exchange channel 2 is closer to a square, the larger the hydraulic diameter, the worse the heat dissipation efficiency; when the cross section of the heat exchange channel 2 is a flatter rectangle, the smaller the hydraulic diameter, and the better the heat dissipation efficiency. In addition, when H / W is larger or smaller, the flatter the rectangular hole, the thinner the film formed by the refrigerant in the heat exchange channel 2, and the better the thermal conductivity of the refrigerant; at the same time, it also makes the distribution of the refrigerant flow path in the heat exchange pipe more uniform.

[0041] Further, by Figure 3It can be seen that when H / W ≤ 0.5 or H / W ≥ 2, the decreasing trend of the relative ratio of the hydraulic diameter is more obvious, that is, the decreasing trend of the hydraulic diameter is more obvious, the change of the heat transfer area is also more obvious, and the improvement of the heat dissipation performance is also more obvious.

[0042] Figure 4 Fig. shows the layout schematic diagram of the heat exchange channels 2 in the flat tube body 1 when H / W ≤ 0.5. Figure 5 Fig. shows the layout schematic diagram of the heat exchange channels 2 in the flat tube body 1 when H / W ≥ 2.

[0043] Preferably, H / W ≥ 2.

[0044] When the value of H / W is less than or equal to 0.5, due to the limitation of the external contour size of the flat tube body 1, when the thickness and width of the flat tube body 1 remain unchanged, the number of the heat exchange channels 2 will decrease, and the water conveyance area of the entire cross-section of the flat tube body 1 will decrease, thereby affecting the refrigerant flow rate to a certain extent, and the flow resistance of the refrigerant will also increase significantly; at the same time, the wall thickness between the second straight side 4 of the rectangular hole and the side wall on one side of the flat tube body 1 in the thickness direction increases, affecting the space utilization rate of the flat tube body 1 and the economy.

[0045] In addition, it should be noted that in the embodiments of the present application, H / W ≥ 2 is a more preferred range, and the effects corresponding to the range of H / W ≤ 0.5 (in terms of the improvement of heat dissipation performance, refrigerant flow rate, refrigerant flow resistance, space utilization rate and economic factors) are weaker than those corresponding to the range of H / W ≥ 2, but are also better than those corresponding to the range of 0.5 < H / W < 2.

[0046] In an embodiment of the present application, preferably, as Figure 5 shown, the thickness of the flat tube body 1 of the microchannel flat tube is T = 1.3 - 1.5 mm, and the thickness of the partition rib 5 between any two adjacent heat exchange channels 2 satisfies 0.1 mm ≤ S ≤ 0.18 mm.

[0047] In this embodiment, the internal space of the flat tube body 1 is divided into a plurality of heat exchange channels 2 by a plurality of partition ribs 5. The partition ribs 5 will occupy the space inside the flat tube body 1. Therefore, the partition ribs 5 have a relatively thin thickness, which can improve the utilization rate of the internal space of the flat tube body 1 by the heat exchange channels 2, and improve the flow-through area and heat dissipation efficiency.

[0048] Preferably, in order to further improve the utilization rate of the flat tube body 1, the four corners of the heat exchange channels 2 are all right angles, and at the same time, the heat exchange channels 2 also have a larger flow-through area.

[0049] In this embodiment, preferably, the thickness S of the spacer 5 is (0.15±0.03) mm. The spacer 5 is processed by a thin rib mold, which is very difficult to manufacture, especially when the product has a rib size of 0.12 mm or less. The processing capacity of the equipment is extremely high, the equipment cost is high, the defect rate is high, and mass production cannot be achieved. In the mold manufacturing process, a 0.1 mm electrode wire is used for cutting. The spark gap and trimming allowance generated are such that the final mold will reach (0.15±0.03) mm, making the thickness S of the spacer 5 = (0.15±0.03) mm.

[0050] In one embodiment of the present application, it is most preferred that the length ratio of the first straight side 3 to the second straight side 4 is 2≤H / W≤3.

[0051] The shape of the heat exchange channel 2 not only affects the heat dissipation efficiency of the refrigerant, but also affects the pressure drop on the refrigerant side. Taking the flat tube body 1 with a width of 12mm and a thickness of 1.4mm as an example, the heat exchange performance and refrigerant side pressure drop of the heat exchange channel 2 under different H / W values ​​are simulated and analyzed by the one-dimensional performance simulation software VI Tool. When H / W=1.17, 1.76, 2.14 and 2.5 are taken respectively, the number of corresponding heat exchange channels 2 is 11 holes, 15 holes, 18 holes and 21 holes respectively. The corresponding heat exchange performance (KW) and refrigerant side pressure drop (pa) are obtained through analysis and calculation by the simulation software, and the Figure 6 The CAE analysis diagram of the heat transfer performance of the flat tube body 1 under different hydraulic diameters shown in FIG. Figure 7 The CAE analysis diagram of the refrigerant side pressure drop in the flat tube body 1 under different hydraulic diameters is shown.

[0052] Depend on Figure 6 It can be seen that when H / W>1, and the wind speed is 2.5m / s or 3m / s, the heat exchange performance increases with the increase of H / W. Figure 7 It can be seen that when H / W>1 and the wind speed is 2.5m / s, as H / W increases, the pressure drop on the refrigerant side also increases continuously, especially when H / W is greater than 3, the pressure drop on the refrigerant side is greater than 80pa, which significantly reduces the energy efficiency ratio (COP) of the vehicle air-conditioning system compressor.

[0053] In one embodiment of the present application, the thickness of the flat tube body 1 is T=1.5 mm, the length of the first straight side 3 of the heat exchange channel 2 is H=1.26 mm, the length of the second straight side 4 is W=0.573 mm, and the thickness of the partition 5 is S=0.15 mm, so that the space of the flat tube body 1 can be fully utilized and materials can be saved; the H / W of the heat exchange channel 2 is H / W=2.2 mm, the hydraulic diameter is small, the heat exchange effect is good, and it can ensure that the compressor of the vehicle air-conditioning system has a good energy efficiency ratio.

[0054] The present application also provides a vehicle air-conditioning condenser, comprising the microchannel flat tube of any of the above embodiments.

[0055] In this embodiment, the vehicle air-conditioning condenser includes microchannel flat tubes, so the vehicle air-conditioning condenser has all the beneficial effects of the microchannel flat tubes, which will not be described in detail here.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A microchannel flat tube, characterized in that: The invention comprises a flat tube body; The flat tube body is formed with a heat exchange channel, the heat exchange channel extends along the length direction of the flat tube body, and the heat exchange channel is used to allow the refrigerant to flow in the flat tube body; The heat exchange channel is formed with a section on the cross section of the flat tube body, and when the cross-sectional area of ​​the section remains unchanged, the shape change of the section can make the heat exchange channel have different hydraulic diameters; The cross section of the heat exchange channel on the cross section of the flat tube body is a rectangular hole; The rectangular hole comprises a first straight side and a second straight side, the first straight side is parallel to the thickness direction of the flat tube body, and the second straight side is parallel to the width direction of the flat tube body; The length of the first straight side is H, and the length of the second straight side is W; A length ratio of the first straight side to the second straight side is 2≤H / W≤3.

2. The microchannel flat tube according to claim 1, characterized in that: There are multiple heat exchange channels, and the multiple heat exchange channels are distributed at intervals along the width direction of the flat tube body; A partition rib is formed between any two adjacent heat exchange channels, and the thickness of the partition rib in the width direction of the flat tube body is S.

3. The microchannel flat tube according to claim 2, characterized in that: The thickness of the partition rib is 0.1 mm≤S≤0.18 mm.

4. The microchannel flat tube according to claim 2, characterized in that: The thickness of the ribs is S=(0.15±0.03) mm.

5. The microchannel flat tube according to claim 1, characterized in that: The thickness of the flat tube body is T, and the thickness of the flat tube body is T=1.3-1.5 mm.

6. The microchannel flat tube according to claim 2, characterized in that: The thickness of the flat tube body is T=1.5 mm, the length of the first straight side is H=1.26 mm, the length of the second straight side is W=0.573 mm, and the thickness of the rib is S=0.15 mm.

7. A vehicle air conditioning condenser, characterized in that: The microchannel flat tube comprises the microchannel flat tube as described in any one of claims 1 to 6.

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