Heat exchanger

Abstract

The application belongs to the technical field of heat exchanger heat transfer enhancement, and provides a heat exchanger, which comprises a flat tube and multiple rows of fins, the flat tube has an outer surface for heat exchange with air; the multiple rows of fins are arranged in different densities along the flow direction of air to form multiple fin groups; multiple fin groups are sequentially arranged on the outer surface of the flat tube along the flow direction of air, so that air can flow through different density areas in sequence between adjacent fins. The application solves the problems of large inlet resistance of equal-interval fins in the existing heat exchanger, insufficient downstream enhancement, and low utilization rate of local heat exchange area.

Description

Technical Field

[0001] This application belongs to the field of heat exchanger enhanced heat transfer technology, and particularly relates to a heat exchanger. Background Technology

[0002] Heat exchangers are key components in refrigerators, air conditioners, heat pump systems, freezers, dehumidifiers, and electronic heat dissipation devices. In air-cooled heat exchangers, the refrigerant or other heat exchange medium typically flows inside flat tubes, microchannel tubes, or heat exchange substrates, while air flows externally over the fins and tube walls, exchanging heat through the tube walls and fins. Since the air-side heat transfer coefficient is usually lower than the refrigerant-side heat transfer coefficient, air-side thermal resistance is often a significant factor limiting the overall performance improvement of the heat exchanger. To reduce air-side thermal resistance, a common approach is to install fins on the outer surface of the refrigerant channel components, increasing the heat exchange area, enhancing airflow turbulence, and disrupting the thermal boundary layer to improve heat exchange efficiency.

[0003] However, existing fin structures typically employ a uniform spacing or density arrangement of most fins along the airflow direction, meaning the spacing between adjacent fins remains essentially constant, and the number of fins per unit length or width is also largely consistent. While this uniformly spaced structure facilitates fabrication and modeling, it does not adequately consider the variations in airflow along the direction of airflow.

[0004] Specifically, when air enters the finned region, the thermal boundary layer near the inlet is still in its initial development stage, with a thin boundary layer and a large temperature difference between the air and the fins. Even a weak disturbance can achieve a certain heat transfer effect. If the fin density in the inlet region is too high, it will lead to a narrow airflow channel, increased inlet wind resistance, and a sharp contraction and deflection of the local airflow, causing unnecessary pressure loss. In this case, too many fins do not necessarily bring a proportional increase in heat transfer; instead, they may reduce airflow and weaken the overall performance of the heat exchanger. As the air continues to flow downstream, the thermal boundary layer on the fin surface gradually thickens, the near-wall temperature gradient decreases, the air-side thermal resistance increases, and the local heat transfer intensity easily decreases. If the same fin spacing and density as the inlet section are used at this point, the disturbance intensity in the downstream region may be insufficient to effectively disrupt the already thickened thermal boundary layer, resulting in insufficient downstream heat transfer and reduced fin area utilization. Summary of the Invention

[0005] The purpose of this application is to provide a heat exchanger to solve the technical problems of high inlet resistance of evenly spaced fins, insufficient downstream enhancement, and low utilization rate of local heat exchange area in existing heat exchangers.

[0006] To achieve the above objectives, the technical solution adopted in this application is as follows: This application provides a heat exchanger, comprising: Flat tube, with an outer surface for heat exchange with air; Multiple rows of fins are arranged at different densities along the direction of air flow to form multiple fin groups; Multiple fin groups are sequentially arranged on the outer surface of the flat tube along the air flow direction, so that air can flow through different density regions between adjacent fins.

[0007] The beneficial effects of the heat exchanger provided in this application are as follows: Compared with the prior art, the heat exchanger of this application changes the local spacing and local density of the fins along the air flow direction, so that different flow areas, heat exchange areas and disturbance intensities are formed at different flow positions, thereby matching the fin arrangement structure with the boundary layer development state and heat exchange demand changes of the air along the flow direction.

[0008] Compared to existing equidistant fin structures, this application does not simply increase the number of fins, nor does it simply decrease the fin spacing. Instead, it spatially distributes the fin density along the airflow direction, allowing the number of fins and the flow area to play different roles in different regions. In this way, without significantly increasing the overall volume of the heat exchanger, it effectively improves local heat transfer matching and the utilization rate of the fin area.

[0009] The first improvement is made to the arrangement of fin groups in different density regions. The multiple fin groups include fin groups in low-density regions and fin groups in high-density regions. The fin groups in low-density regions and the fin groups in high-density regions are arranged sequentially on the outer surface of the flat tube along the air flow direction.

[0010] The above technical solution has the following advantages or beneficial effects: The fins on the flat tube are arranged in a "sparse at the front and dense at the back" structure. The fin density is reduced in the inlet section to allow the airflow to enter the heat exchanger more smoothly, while the fin density is increased in the downstream section to create stronger airflow disturbance and obtain a larger heat exchange area. This structure is particularly suitable for condensers or long-flow heat exchangers where downstream heat exchange attenuation is significant.

[0011] A second improvement is made to the arrangement of fin groups in different density regions. The multiple fin groups include fin groups in low-density regions and fin groups in high-density regions. The fin groups in high-density regions and the fin groups in low-density regions are arranged sequentially on the outer surface of the flat tube along the airflow direction.

[0012] The above technical solution has the following advantages or beneficial effects: The fins on the flat tube are arranged in a "dense at the front and sparse at the back" structure. The fin density is increased in the inlet section to rapidly enhance inlet heat transfer, while the fin density is reduced in the downstream section to decrease pressure drop and improve airflow. This structure is suitable for operating conditions with strong inlet heat transfer requirements or sensitive outlet pressure drop.

[0013] A third improvement is made to the arrangement of fin groups in different density regions. The multiple fin groups include a fin group in a first low-density region, a fin group in a second low-density region, and a fin group in a high-density region. The fin groups in the first low-density region, the fin group in the high-density region, and the fin group in the second low-density region are arranged sequentially on the outer surface of the flat tube along the air flow direction.

[0014] The above technical solution has the following advantages or beneficial effects: Arranging the fins on the flat tube in a "sparse-dense-sparse" pattern creates a combined effect of low-resistance flow at the inlet, enhanced heat transfer in the middle section, and low-resistance discharge at the outlet. This structure is suitable for heat exchangers with high heat transfer loads in the middle section or where it is desirable to control the outlet resistance.

[0015] A fourth improvement is made to the arrangement of fin groups in different density regions. The multiple fin groups include a fin group in a first high-density region, a fin group in a second high-density region, and a fin group in a low-density region. The fin group in the first high-density region, the fin group in the low-density region, and the fin group in the second high-density region are arranged sequentially on the outer surface of the flat tube along the air flow direction.

[0016] The above technical solution has the following advantages or beneficial effects: Arranging the fins on the flat tube into a "dense-sparse-dense" structure can create a multi-stage perturbation process involving inlet reinforcement, mid-section recovery, and subsequent reinforcement. This structure is suitable for scenarios requiring multiple interruptions to boundary layer development.

[0017] A fifth improvement is made to the arrangement of fin groups in different density regions. The multiple fin groups include fin groups in low-density regions, fin groups in medium-density regions, and fin groups in high-density regions. The fin groups in low-density regions, medium-density regions, and high-density regions are arranged sequentially on the outer surface of the flat tube along the airflow direction. Alternatively, the fin groups in the high-density region, the fin groups in the medium-density region, and the fin groups in the low-density region are sequentially arranged on the outer surface of the flat tube along the airflow direction.

[0018] The above technical solution has the following advantages or beneficial effects: Arranging the fins on the flat tube into a multi-segment or continuous gradient structure can further reduce abrupt flow changes between adjacent segments, making density changes smoother and helping to reduce local pressure fluctuations and noise risks.

[0019] The density setting of the fins is improved so that the local fin density in the fin group satisfies a smooth gradient relationship.

[0020] The above technical solution has the following advantages or beneficial effects: The fin arrangement density should change gradually at the inlet and outlet ends to avoid abrupt changes that could cause local flow separation.

[0021] The shape of the fins is improved, and the fins are wavy fins. The outer surface of the flat tube has fin groups located in the windward side region, fin groups in the middle region, and fin groups in the leeward side region, and the wave amplitude of the fin groups in the windward side region, the fin groups in the middle region, and the fin groups in the leeward side region decreases sequentially.

[0022] The above technical solution has the following advantages or beneficial effects: A large-amplitude structure is set in the fin group on the windward side, a moderate transition amplitude is used in the fin group in the middle area, and the amplitude is reduced in the fin group on the leeward side, thereby achieving a balance between enhancing heat transfer and reducing pressure drop.

[0023] In one embodiment, the fin thickness in the fin group on the windward side is greater than the fin thickness in the fin group on the leeward side.

[0024] The above technical solution has the following advantages or beneficial effects: In the windward side of the heat exchanger, increasing the fin thickness enhances thermal conductivity, allowing heat to be quickly transferred to the air side; in the leeward side, reducing the fin thickness increases the effective flow area, thereby reducing resistance.

[0025] The arrangement of the fins is further improved, with the fins in adjacent fin groups arranged in an alternating pattern along the airflow direction.

[0026] The above technical solution has the following advantages or beneficial effects: Because of the misalignment between adjacent rows of fins, the wake formed after air passes through the first row of fins in one fin group will not directly enter the same position in the next row of another fin group. Instead, it will be subjected to new disturbances from the second row of fins in the other fin group. Therefore, this helps to reduce the formation of stable flow channels, enhance lateral mixing, and improve fluid exchange between different rows of fins. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 A three-dimensional structural diagram of the heat exchanger provided in the embodiments of this application. Figure 1 ; Figure 2 A top view of the first layout of the fins on the flat tube provided in the embodiments of this application; Figure 3 A three-dimensional structural schematic diagram of the first layout of the fins on the flat tube provided in the embodiments of this application; Figure 4 A top view of the second layout of the fins on the flat tube provided in the embodiments of this application; Figure 5 A top view of the third layout of the flat tube upper fins provided in the embodiments of this application; Figure 6 A top view of the fourth layout of the flat tube upper fins provided in the embodiments of this application; Figure 7 A top view schematic diagram of the fifth layout of the fins on the flat tube provided in the embodiments of this application; Figure 8 A three-dimensional structural schematic diagram of the sixth layout of the fins on the flat tube provided in the embodiments of this application; Figure 9 A top view of the sixth layout of the fins on the flat tube provided in the embodiments of this application; Figure 10 A schematic diagram showing the fins using a smooth, gradient density function provided in the embodiments of this application; Figure 11 A three-dimensional structural schematic diagram of the seventh layout of the fins on the flat tube provided in the embodiments of this application; Figure 12 A top view of the seventh layout of the fins on the flat tube provided in the embodiments of this application; Figure 13 A three-dimensional structural schematic diagram of the eighth layout of the fins on the flat tube provided in the embodiments of this application; Figure 14 This is a top view of the ninth layout of the flat tube upper fins provided in the embodiments of this application.

[0029] The following are the labeling elements in the figure: 1-flat tube; 2-Fin; 20-Fin group; 21 - Fin group in low-density region; 21a - Fin group in first low-density region; 21b - Fin group in second low-density region; 22 - Fin group in high-density region; 22a - Fin group in first high-density region; 22b - Fin group in second high-density region; 23 - Fin group in the medium density region; 24 - Fin group on the windward side; 25 - Fin group in the middle area; 26 - Fin group on the leeward side. Detailed Implementation

[0030] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0031] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0032] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0033] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0034] Traditional fin structures employ equal spacing or density along the airflow direction, meaning the spacing between adjacent fins remains essentially constant, and the number of fins per unit length or width is also relatively consistent. While this equal-spacing structure facilitates fabrication and modeling, it doesn't adequately consider the changes in airflow along the direction of flow. Specifically, when air enters the finned region, the thermal boundary layer near the inlet is still in its initial development stage, resulting in a thin boundary layer, a large temperature difference between the air and the fins, and the ability to achieve some heat transfer even with weak disturbances. If the fin density in the inlet area is too high, it leads to an excessively narrow airflow channel, increased inlet wind resistance, and sharp contraction and deflection of local airflow, causing unnecessary pressure loss. In this case, too many fins do not necessarily result in a proportional increase in heat transfer; instead, they may reduce airflow and weaken the overall performance of the heat exchanger. As the air continues to flow downstream, the thermal boundary layer on the fin surface gradually thickens, the near-wall temperature gradient decreases, the air-side thermal resistance increases, and the local heat transfer intensity easily diminishes. If the same fin spacing and fin density as the inlet section are used at this time, the disturbance intensity in the downstream area may be insufficient, making it difficult to effectively destroy the already thickened thermal boundary layer, resulting in problems such as insufficient downstream heat exchange and reduced fin area utilization.

[0035] Furthermore, under certain operating conditions, the inlet section of the heat exchanger needs to bear a strong heat transfer load, or the air inlet velocity is low, requiring rapid establishment of disturbances and mixing in the inlet region; while the downstream region needs to maintain smooth airflow, reduce resistance, and improve air exhaust stability. In such cases, if an equal-density arrangement is still used, it is impossible to differentiate the design of different flow direction regions according to local heat transfer requirements and local resistance control requirements.

[0036] In related technologies, a structure with multiple rows of fins arranged on a flat outer surface is employed. These fins divide the multiple rows of fins into a first fin region, a second fin region, and a third fin region along the medium flow direction inside the flat tube. The fin spacing in the second fin region is smaller than that in the first and third fin regions, forming a non-uniform fin spacing structure with localized "sparse-dense-sparse" patterns. The fin spacing variation in this related technology mainly occurs at different spatial positions along the medium flow direction inside the flat tube. For the air side of the heat exchanger, this direction generally falls between the vertical and horizontal directions of the main airflow. Different density regions create different flow resistances on the windward side of the heat exchanger, thereby regulating the airflow in different windward regions. Specifically, in this fin arrangement of related technologies, the different fin density regions mainly correspond to different positions in the transverse space of the airflow field. Air in the central region of the heat exchanger may mainly pass through the dense region, while air in the peripheral region mainly passes through the sparse region; it is not required that the same stream of air sequentially passes through multiple different density regions during its flow.

[0037] The aforementioned heat exchanger structure primarily addresses the problem of uneven air distribution between the fan and the heat exchanger. Since the fan projection is typically circular, while the airflow face of the heat exchanger is usually square or rectangular, the matching of the fan and heat exchanger often results in higher airflow velocity in the central area and lower airflow velocity at the edges and corners. Therefore, by setting different fin spacings at different positions on the airflow face of the heat exchanger, the local airflow resistance is altered, allowing the uneven airflow to be redistributed, thereby obtaining a more uniform or specifically distributed airflow field and improving the metal utilization rate of different airflow areas of the heat exchanger. However, this application cannot solve the problem that traditional evenly spaced fins cannot adapt to the constantly changing airflow pattern.

[0038] Therefore, this application provides a novel heat exchanger that improves the fin structure on a flat tube. By modifying the traditional equal-spacing fins into an arrangement with varying densities along the airflow direction, the fins achieve different local flow capacities, heat transfer areas, and disturbance intensities in different flow regions. This structure can be segmented and matched according to the development of the air boundary layer and local heat transfer requirements, which helps to improve the problems of high inlet resistance, insufficient downstream enhancement, or low utilization rate of local heat transfer area in traditional equal-spacing fins. A detailed description follows.

[0039] The heat exchanger provided in this application embodiment can be applied to refrigeration equipment such as refrigerator condensers, air conditioner heat exchangers, heat pump heat exchangers, microchannel heat exchangers and other compact air-cooled heat exchangers. It is beneficial to increase the heat exchange per unit volume in a limited space, thereby reducing the thermal resistance on the air side and improving the overall energy efficiency.

[0040] Please see Figure 1 The heat exchanger includes at least a flat tube 1 and multiple rows of fins 2 disposed on the flat tube 1. The flat tube 1 has an outer surface for heat exchange with air, and the fins 2 are integrally connected to the outer surface of the flat tube 1. In this embodiment, one or more refrigerant flow channels can be provided inside the flat tube 1, allowing the refrigerant to flow in a predetermined direction. In other embodiments, a plate channel or heat exchange substrate may be used instead of the structure of the flat tube 1.

[0041] Multiple rows of fins 2 are spaced apart on the outer surface of the flat tube 1. They can preferably be integrally formed with the outer surface of the flat tube 1 by cutting, or they can be connected by stamping, bending, welding, brazing, mechanical pressing, or other methods. The fins 2 and the flat tube 1 are formed integrally by cutting to reduce the contact thermal resistance between them. Air flows through adjacent fins 2 in the flow direction, forming airflow channels and exchanging heat with the fin surface, which helps to expand the heat exchange area on the air side and enhance airflow turbulence. The fins 2 can preferably be corrugated, streamlined, arc-shaped, or other structures that guide airflow and enhance heat exchange.

[0042] Please see Figure 1 Multiple rows of fins 2 are arranged with different densities along the airflow direction to form multiple fin groups 20. Here, "density" refers to the spacing between adjacent rows of fins 2; a larger spacing indicates low density, and a smaller spacing indicates high density. As an example, multiple rows of low-density fins 2 form one fin group 20, and multiple rows of high-density fins 2 form another fin group 20.

[0043] Multiple fin groups 20 of different densities are sequentially arranged on the outer surface of the flat tube 1 along the direction of air flow, so that air can flow through different density regions between adjacent fins 2.

[0044] Specifically, such as Figure 1 and Figure 2 As shown, multiple fins 2 are spaced apart along the airflow direction, which is defined as the x-direction. The effective flow length of the fins 2 along the airflow direction is Lf, where 0 ≤ x ≤ Lf. Let the local fin spacing between two adjacent fins 2 at any flow position x be P(x), and the local fin density be D(x), satisfying: D(x) = 1 / P(x) Wherein, P(x) is used to represent the local channel width between adjacent fins 2, and D(x) is used to represent the local number density of fins 2 within a unit arrangement length.

[0045] In conventional fin 2, P(x) = P0, which is a constant; D(x) = D0, which is also a constant. However, in this embodiment, P(x) and / or D(x) are not constant along the airflow direction. That is, fin 2 can have different local spacing and local density in the inlet section, middle section, and downstream section. This means that, unlike conventional equally spaced fin 2, P(x) and / or D(x) in this embodiment are not constant along the airflow direction, allowing multiple fins 2 to form a structure with variable spacing or variable density along the airflow direction.

[0046] The core of this structure is not simply increasing or decreasing the number of fins 2, but rather matching and controlling the density of fins 2 in different regions according to the changes in the airflow state. The inlet section can be set to a more sparse arrangement to reduce inlet resistance; the middle and rear sections can be set to a more dense arrangement to enhance the heat exchange area and turbulence intensity; alternatively, the inlet section can be set to a more dense arrangement according to actual operating conditions, so that the air will be rapidly disturbed after entering the heat exchanger.

[0047] Thus, through the above structure, the local density of fin 2 can change along the airflow direction, so that different flow directions have different flow areas, heat transfer areas and disturbance intensities, thereby improving the problem of the single structural parameters of traditional equal-spacing fin 2.

[0048] Compared with the prior art, the heat exchanger provided in this application embodiment changes the local spacing and local density of the fins 2 along the air flow direction, so that different flow areas, heat exchange areas and disturbance intensities are formed at different flow positions, thereby matching the fin arrangement structure with the boundary layer development state and heat exchange demand changes of the air along the flow direction.

[0049] As can be seen, compared with the existing equidistant fin structure, this application does not simply increase the number of fins 2, nor does it simply reduce the spacing between fins 2. Instead, it spatially distributes the density of fins 2 in the airflow direction, allowing the number of fins 2 and the flow area to play different roles in different regions. In this way, without significantly increasing the overall volume of the heat exchanger, the local heat transfer matching and the utilization rate of the fin area are effectively improved.

[0050] Furthermore, compared to the aforementioned related technologies, the heat exchanger in this application embodiment explicitly uses the airflow direction itself as the direction of density change of the fins 2. Let the airflow direction be the x-direction, and both the local fin spacing P(x) and the local fin density D(x) are functions of the airflow direction coordinate x, i.e.: P = P(x), D = D(x). Therefore, when the same stream of air enters the heat exchanger, it moves downstream along the airflow direction, successively passing through functional zones with different fin spacing or fin density. For example, in a "sparse-to-dense" structure, the air first flows through the low-density zone and then enters the high-density zone; in a "sparse-dense-sparse" structure, the same stream of air sequentially passes through the low-density zone, the high-density zone, and the low-density zone again. It is evident that this application focuses on the degree of disturbance and heat transfer enhancement that air should experience at different stages of its flow. Compared to the aforementioned related technologies, although both employ a non-uniform fin spacing design, their density change coordinates differ, resulting in significantly different airflow control mechanisms.

[0051] The different density regions in this application belong to the functional zoning of airflow direction. The density of fins 2 in each region is designed according to the boundary layer development state of air along the flow direction, local heat exchange requirements, and pressure loss requirements. Therefore, the positions of fin groups 20 in the different density regions of this application are not different lateral positions on the windward side of the heat exchanger, but rather different flow sections that the air passes through sequentially along the mainstream direction, so that the air can flow through different density regions sequentially in the flow between adjacent fins 2.

[0052] As can be seen, the heat exchanger provided in this application, by configuring different fin densities along the mainstream airflow direction, adapts the disturbance intensity, heat transfer area, and flow capacity of the inlet, middle, and rear sections to the local airside conditions, reducing unnecessary pressure loss in the inlet region. It also specifically enhances the disturbance intensity in the middle and rear sections after boundary layer development, effectively improving the downstream heat transfer attenuation problem inherent in traditional evenly spaced fins. Furthermore, the exhaust resistance can be reduced through the low-density outlet region, allowing for graded coordination of heat transfer enhancement and pressure drop control along the airflow direction.

[0053] Furthermore, the heat exchanger structure provided in this application embodiment is simple, mainly achieved by changing the fin spacing and array density, without introducing overly complex curved surfaces, micro-pores, or difficult-to-manufacture turbulence structures. For modeling, it can be achieved through segmented sketches, segmented arrays, or curve-driven arrays. For actual manufacturing, it can also be achieved by adjusting the cutting tool path, stamping die spacing, or fin insertion spacing, exhibiting good machining feasibility.

[0054] For the arrangement of fin groups 20 with different densities on the outer surface of the flat tube 1, the following forms are included but not limited to: Please refer to the first embodiment of this application as well. Figure 2 and Figure 3 Multiple fin groups 20 include fin group 21 in a low-density region and fin group 22 in a high-density region. The fin group 21 in the low-density region and the fin group 22 in the high-density region are arranged sequentially on the outer surface of the flat tube 1 along the air flow direction.

[0055] In this embodiment, multiple fins 2 are divided into two density regions along the airflow direction, including a fin group 21 in the front low-density region and a fin group 22 in the rear high-density region.

[0056] The fin assembly 21 in the low-density front section is located on the air inlet side, and the fin assembly 22 in the high-density rear section is located on the air outlet side or near the outlet side. Let the flow length of the low-density front section be L1, and the flow length of the high-density rear section be L2, then: L1 + L2 + Lt = Lf Wherein, L1 can be from 0.20Lf to 0.70Lf, and L2 can be from 0.30Lf to 0.80Lf. Preferably, L1 is from 0.35Lf to 0.55Lf, and L2 is from 0.45Lf to 0.65Lf.

[0057] Let P1 be the average fin spacing of fins 2 in the fin group 21 of the front low-density region, and D1 be the average fin density of fins 2; let P2 be the average fin spacing of fins 2 in the fin group 22 of the rear high-density region, and D2 be the average fin density of fins 2. This structure, with sparser fins at the front and denser fins at the rear, satisfies: P1>P2 D1 <D2 Wherein, P1 can be 2.5mm to 4.0mm, and P2 can be 1.0mm to 2.5mm. Preferably, P1 is 2.5mm to 3.5mm, and P2 is 1.5mm to 2.0mm.

[0058] This structure is suitable for heat exchangers where the air boundary layer develops significantly along the flow path. When air first enters the fin region 2, the boundary layer is thin, and there is a large temperature difference and velocity gradient between the airflow and the fin surface 2. A relatively low fin density 2 is sufficient to meet basic heat exchange requirements. If the fins 2 are too dense in the inlet section, it will lead to a narrowing of the airflow channel, an increase in local inlet resistance, and even cause some airflow to bypass or become unevenly distributed. Therefore, the fin group 21 in the low-density region at the front reduces inlet resistance through a larger fin spacing 2, allowing the airflow to enter the heat exchanger more smoothly.

[0059] As air continues to flow along the flow direction, the thermal boundary layer gradually thickens, increasing the thermal resistance on the air side. Traditional iso-density fins 2 are prone to heat transfer attenuation in the downstream region. In this embodiment, the fin group 22 in the high-density region of the rear section is equipped with a smaller fin spacing and a higher fin density, which increases the number of fins 2 per unit area, increases the heat transfer area, and enhances the local flow channel contraction. This generates a more obvious velocity gradient and disturbance in the airflow in the rear section, which is beneficial for breaking down the thickened thermal boundary layer downstream.

[0060] Therefore, the sparse-at-the-front, dense-at-the-back structure can achieve a functional distribution method of low-resistance inlet introduction and enhanced heat transfer downstream. Compared with the traditional equal-spacing structure, this structure can reduce unnecessary resistance loss at the inlet and concentrate the stronger structural disturbances in the downstream area where enhanced heat transfer is more needed, thereby improving the area utilization of fins 2.

[0061] In the second embodiment of this application, please refer to Figure 4 Multiple fin groups 20 include fin groups 21 in low-density regions and fin groups 22 in high-density regions. The fin groups 22 in high-density regions and fin groups 21 in low-density regions are sequentially arranged on the outer surface of the flat tube 1 along the air flow direction.

[0062] In this embodiment, multiple fins 2 are divided into two density regions along the airflow direction, including a fin group 22 in the front high-density region and a fin group 21 in the rear low-density region.

[0063] Let P1 be the average fin spacing of fins 2 in the high-density fin group 22 at the front, and D1 be the average fin density of fins 2; let P2 be the average fin spacing of fins 2 in the low-density fin group 21 at the rear, and D2 be the average fin density of fins 2. The structure with a denser front and sparser rear satisfies: P1 <P2 D1>D2 Wherein, P1 can be 1.0mm to 2.5mm, and P2 can be 2.5mm to 4.0mm. Preferably, P1 is 1.5mm to 2.0mm, and P2 is 2.5mm to 3.5mm.

[0064] This structure is suitable for heat exchangers with high inlet heat exchange requirements or low air inlet velocity that require rapid establishment of disturbance. For example, in some small air-cooled condensers, the temperature difference is large in the area that air first contacts after entering the heat exchanger. If the inlet section can rapidly enhance the disturbance and contact between the air and the fins 2, it will help improve the heat exchange intensity in the inlet area. In this case, setting a higher fin density in the fin group 22 in the high-density area of ​​the front section can make the air receive a strong guiding and disturbance effect as soon as it enters the heat exchanger, promoting the mixing of near-wall air with mainstream air.

[0065] In the lower-density region of the rear section, the fin group 21 has a gradually increasing or maintained large fin spacing, which increases the airflow area and reduces local resistance, thus helping to reduce the overall pressure drop of the heat exchanger. At the same time, the sparser rear section arrangement can improve the stability of air discharge and reduce eddy buildup and local stagnation at the outlet.

[0066] As can be seen, the structure with a denser inlet and a sparser outlet can create a functional distribution pattern that allows for rapid inlet heat enhancement and low-resistance outlet discharge downstream. This structure is particularly suitable for heat exchangers that require high heat exchange capacity at the inlet but are limited by overall pressure drop.

[0067] In the third embodiment of this application, please refer to Figure 5 Multiple fin groups 20 include a first low-density region fin group 21a, a second low-density region fin group 21b, and a high-density region fin group 22. The first low-density region fin group 21a, the high-density region fin group 22, and the second low-density region fin group 21b are sequentially arranged on the outer surface of the flat tube 1 along the air flow direction.

[0068] In this embodiment, the multi-row fins 2 are divided into three density regions along the airflow direction, including the fin group 21a in the first low-density region at the front, the fin group 22 in the high-density region in the middle, and the fin group 21b in the second low-density region at the rear.

[0069] Let the average fin density of the three density regions be D1, D2, and D3, respectively, and the corresponding average fin spacing be P1, P2, and P3. This sparse-dense structure satisfies: D2>D1 D2>D3 Correspondingly: P2 <P1 P2 <P3 Among them, the fin group 21a in the first low-density region at the front is used for airflow inlet introduction, the fin group 22 in the middle high-density region is used for main heat exchange enhancement, and the fin group 21b in the second low-density region at the rear is used to reduce outlet resistance and improve airflow discharge.

[0070] This structure is suitable for scenarios where the middle section of the heat exchanger is the main area for enhanced heat transfer. When air first enters the fin 2 region at the inlet, the fin group 21a in the first low-density region of the front section is arranged more sparsely to reduce inlet impact. When the air flows to the middle section, the boundary layer has developed to a certain thickness. At this time, the fin group 22 in the middle high-density region can concentrate and enhance heat transfer. When the air approaches the outlet, the fin group 21b in the second low-density region of the rear section can appropriately widen the flow channel and reduce outlet resistance and noise risk.

[0071] As an example, in one implementation, the lengths of the three density regions can satisfy: L1=0.3Lf L2=0.3Lf L3=0.3Lf The fin spacing in the three sections can meet the following requirements: P1=2.5mm P2=1.5mm P3=2.5mm The density corresponding to fin 2 is: D1=1 / 2.5 D2 = 1 / 1.5 D3 = 1 / 2.5 This structure results in the highest fin density on the fin group 22 in the high-density region of the middle section, while the inlet and outlet are relatively sparse, which can enhance the heat exchange in the middle section while controlling the overall pressure drop.

[0072] As an example, in another embodiment (not shown in the figure), if the flow length of the heat exchanger is short, the fin group 21a in the first low-density region can be shortened, and the fin group 22 in the middle high-density region can be arranged earlier, so that enhanced heat transfer can be initiated earlier. If the heat exchanger is more sensitive to pressure drop, the length of the fin group 21b in the second low-density region can be appropriately increased to maintain better flow capacity in the outlet section.

[0073] In the fourth embodiment of this application, please refer to Figure 6 Multiple fin groups 20 include a first high-density region fin group 22a, a second high-density region fin group 22b, and a low-density region fin group 21. The first high-density region fin group 22a, the low-density region fin group 21, and the second high-density region fin group 22b are sequentially arranged on the outer surface of the flat tube 1 along the air flow direction.

[0074] In this embodiment, the multiple fins 2 are divided into three density regions along the airflow direction, including a fin group 22a in the first high-density region at the front, a fin group 21 in the middle low-density region, and a fin group 22b in the second high-density region at the rear.

[0075] Let the average fin density of the three density regions be D1, D2, and D3, respectively, and the corresponding average fin spacing be P1, P2, and P3. This density-sparse structure satisfies: D1>D2 D3>D2 Correspondingly: P1 <P2 P3 <P2 This structure is suitable for heat exchangers that require enhanced disturbance in the inlet and downstream regions, while reducing resistance or forming a buffer channel in the middle section. The fin group 22a in the first high-density region at the front can quickly establish disturbance and heat transfer when the air first enters the heat exchanger; the fin group 21 in the low-density region in the middle section can provide some recovery space for the airflow and reduce the pressure drop accumulation caused by continuous high-density arrangement; the fin group 22b in the second high-density region at the rear section is used to further enhance downstream heat transfer and disrupt the thickened boundary layer in the downstream section.

[0076] As an example, the lengths of these three segments can satisfy: L1=0.30Lf L2=0.30Lf L3=0.40Lf The spacing between the three fin sections 2 can meet the following requirements: P1=2.0mm P2=3.5mm P3=2.2mm This arrangement causes the air to first undergo enhanced turbulence in the first high-density region of the inlet fin group 22a, then enter the low-resistance transition of the middle low-density region fin group 21, and finally enter the enhanced heat exchange of the second high-density region fin group 22b, thus forming a multi-stage turbulence process.

[0077] This dense-sparse structure is also suitable for heat exchangers with limited local space. For example, when the middle section of the heat exchanger is close to structural supports, mounting brackets, or duct bends, the low-density fin group 21 in the middle section can reduce the risk of blockage by using a low-density arrangement; while arranging the first high-density fin group 22a in the front section and the second high-density fin group 22b in the rear section on the inlet and outlet sides with a high-density arrangement can compensate for the heat exchange area loss caused by the low density in the middle section.

[0078] In the fifth embodiment of this application, please refer to Figure 7Multiple fin groups 20 include a low-density fin group 21, a medium-density fin group 23, and a high-density fin group 22. The low-density fin group 21, the medium-density fin group 23, and the high-density fin group 22 are sequentially arranged on the outer surface of the flat tube 1 along the air flow direction.

[0079] Alternatively, please refer to the following: Figure 8 and Figure 9 The fin group 22 in the high-density region, the fin group 23 in the medium-density region, and the fin group 21 in the low-density region are sequentially arranged on the outer surface of the flat tube 1 along the air flow direction.

[0080] As an example, the multi-row fins 2 are divided into N density regions along the airflow direction, where 2 ≤ N ≤ 6. The lengths of each density region are L1, L2, ..., LN, and satisfy the following: ΣLi+ΣLt=Lf 0.10Lf≤Li≤0.70Lf The average fin spacing 2 of each density region is P1, P2, ..., PN, and the corresponding average fin density 2 is D1, D2, ..., DN, respectively, satisfying the following: Di=1 / Pi Specifically, the multi-segment variable-density arrangement described above can be flexibly designed according to the actual heat exchanger structure. For example, the following rules can be adopted: The first arrangement consists of fin groups 21 in the low-density region, fin groups 23 in the medium-density region, and fin groups 22 in the high-density region, arranged sequentially. D1 <D2<D3 This structure is suitable for heat exchangers where the boundary layer gradually thickens along the flow direction and downstream heat transfer attenuation is significant. The density of fins 2 gradually increases along the flow direction, thus gradually enhancing the disturbance intensity.

[0081] The second type involves fin groups 22 in the high-density region, fin groups 23 in the medium-density region, and fin groups 21 in the low-density region arranged sequentially. D1>D2>D3 This structure is suitable for heat exchangers with high inlet heat transfer load and downstream pressure drop sensitivity. The density of fins 2 gradually decreases along the flow direction, which enhances heat transfer at the inlet and reduces resistance downstream.

[0082] The third type involves fin groups 21 in the low-density region, fin groups 22 in the high-density region, fin groups 23 in the medium-density region, and fin groups 22 in the high-density region arranged sequentially. D2>D1, D4>D3 This structure is suitable for heat exchangers that require two enhanced disturbances, and can form enhanced heat transfer zones in the front and rear sections respectively.

[0083] The fourth type involves fin groups 23 in the medium-density region, fin groups 21 in the low-density region, fin groups 22 in the high-density region, and fin groups 21 in the low-density region arranged sequentially. D3>D1>D2,D3>D4 This structure is suitable for heat exchangers where the middle and rear sections are the main heat exchange bottlenecks and resistance needs to be controlled at both the inlet and outlet.

[0084] The fifth type consists of fin groups 21 in the low-density region, fin groups 23 in the medium-density region, fin groups 22 in the high-density region, fin groups 23 in the medium-density region, and fin groups 21 in the low-density region arranged sequentially. D1 <D2<D3,D3> D4>D5 This structure is suitable for heat exchangers with the highest heat exchange demand in the middle section and where low-resistance flow guidance needs to be maintained at the inlet and outlet.

[0085] As can be seen, fin 2 is divided into four, five, or six density zones along the airflow direction. Each density zone can be set according to the five rules mentioned above, or it can be adjusted according to the actual heat exchanger wind speed distribution, temperature distribution, structural space, and pressure drop requirements.

[0086] Therefore, the advantage of a multi-segment structure lies in its ability to more precisely match the local flow conditions on the air side. For large condensers or long-flow heat exchangers, the changes in air conditions along the flow direction are more pronounced, and a two-segment design may not be sufficient to precisely control local resistance and local heat transfer. In such cases, a multi-segment arrangement can smooth out density changes and can also enhance localized areas of weak heat transfer.

[0087] Regarding the spacing of the local fins 2, in one embodiment of this application, the spacing P(x) of the local fins 2 satisfies a piecewise constant relationship: P(x) = Pi, xi-1 ≤ x <xi Where i = 1, 2, ..., N; N is the number of density regions; x0 = 0, xN = Lf; Pi is the average fin spacing in the i-th density region. This scheme has a simple structure, is easy to model using segmented arrays, and is also convenient for actual processing and dimensional inspection.

[0088] Based on the above, for the density setting of local fin 2, the density D(x) of local fin 2 satisfies a piecewise constant relationship: D(x) = Di, xi-1 ≤ x <xi Where Di is the average density of fin 2 in the i-th density region. Since D(x) = 1 / P(x), changing D(x) can change the local flow spacing between adjacent fins 2.

[0089] Regarding the spacing of the local fins 2, in another embodiment of this application, the spacing P(x) of the local fins 2 satisfies a continuous gradual change relationship: P(x)=Pin+(Pout-Pin)(x / Lf)m wherein Pin is the pitch of fins 2 at the inlet end, Pout is the pitch of fins 2 at the outlet end, m is a pitch variation control factor, and 0.5≤m≤3. When Pout<Pin, the pitch of fins 2 gradually decreases along the flow direction, and the density of fins 2 gradually increases along the flow direction; when Pout>Pin, the pitch of fins 2 gradually increases along the flow direction, and the density of fins 2 gradually decreases along the flow direction.

[0090] On this basis, the local density D(x) of fins 2 satisfies a continuous gradual change relationship: D(x)=Din+(Dout-Din)(x / Lf)m wherein Din is the density of fins 2 at the inlet end, Dout is the density of fins 2 at the outlet end, m is a density variation control factor, and 0.5≤m≤3. When Dout>Din, the density of fins 2 gradually increases along the flow direction; when Dout<Din, the density of fins 2 gradually decreases along the flow direction.

[0091] For the fin 2 density setting in the form of smooth gradual change, in one embodiment of the present application, please refer to Figure 10 , the local fin 2 density in the fin group 20 satisfies a smooth gradual change relationship, so that the inlet end and the outlet end for air inflow and outflow on the fin group 20 have a small inclination rate.

[0092] As an example, the local fin 2 density D(x) adopts a smooth gradual change function: D(x)=Din+(Dout-Din)[3(x / Lf)²-2(x / Lf)³] wherein Din is the density of fins 2 at the inlet end, and Dout is the density of fins 2 at the outlet end.

[0093] If Pin is 1.5 and Pout is 2.5: D(x)=0.67+0.27 [3 (x / 25.4)²-2 (x / 25.4)³] In this function, 3s²-2s³ is a smooth transition function, where s=x / Lf. The slope of this function at s=0 and s=1 is 0. Therefore, the arrangement density of fins 2 changes gently at the inlet end and the outlet end, avoiding local flow separation caused by sudden change.

[0094] When Dout>Din, this function forms a smooth gradual change structure that is sparse at the front and dense at the rear. When Dout<Din, this function forms a smooth gradual change structure that is dense at the front and sparse at the rear.

[0095] Compared with piecewise constant structures, smooth gradient structures can make the airflow channel changes more continuous and reduce local pressure abrupt changes. Compared with simple linear gradients, smooth gradient structures have a gentler transition at the inlet and outlet, making them suitable for heat exchangers with high requirements for noise, pressure drop fluctuations, or airflow stability.

[0096] In actual manufacturing, strictly continuously varying fin density can be achieved through discretization. For example, Lf can be divided into multiple small segments, and the fin spacing and density within each segment can be calculated using intermediate coordinates. The fin spacing of each segment can be calculated using the aforementioned smoothing function. This approach can approximate a continuously varying density while reducing the difficulty of processing and modeling.

[0097] As an example, in one implementation, the local fin density D(x) satisfies a smooth gradient relationship: D(x)=Din+(Dout-Din)[3(x / Lf)²-2(x / Lf)³] This smooth gradient function has a small slope at the inlet and outlet ends, which can avoid problems such as local flow separation, pressure fluctuations or discontinuous structural transitions caused by abrupt density changes.

[0098] The spacing P(x) between the two local fins satisfies: Pmin≤P(x)≤Pmax Wherein, Pmin is the minimum allowable fin spacing 2, and Pmax is the maximum allowable fin spacing 2. Setting Pmin avoids excessively dense fins 2, which could lead to air channel blockage, increased dust accumulation, or processing difficulties; setting Pmax avoids excessively sparse fins 2, which could result in insufficient heat exchange area and reduced turbulence capacity. Preferably, 1.0mm ≤ Pmin ≤ 2.0mm, and 2.5mm ≤ Pmax ≤ 4.0mm. For refrigerator condensers, microchannel condensers, or small air-cooled heat exchangers, P(x) is preferably between 1.5mm and 3.5mm.

[0099] In another embodiment, the average fin density ratio of two adjacent density regions satisfies: 0.5≤Di+1 / Di≤2.0 More preferably, satisfy: 0.67≤Di+1 / Di≤1.50 By limiting the density ratio of adjacent density regions, it is possible to avoid excessive changes in density between adjacent regions that could lead to sudden contraction or expansion of the flow channel, thereby reducing the risk of sudden changes in local resistance and airflow separation.

[0100] In another embodiment, a transition zone is provided between two adjacent density regions, and the flow length Lt of the transition zone satisfies: 0.02Lf≤Lt≤0.20Lf The spacing between the fins 2 in the transition zone can gradually change from the fin spacing in the upstream density region to the length in the downstream density region. This transition zone can be a straight transition. For fins 2 that are integrally formed by cutting, this can also be achieved by changing the start and end positions of adjacent fins 2 or the local transition spacing.

[0101] In practical applications, existing flat-tube shovel-shaped fins typically employ a uniform waveform function; for example, all fins 2 within the entire heat exchange area use the same amplitude, period, and curvature. While this structure is easy to manufacture, it cannot adapt to the varying flow characteristics of air along its direction.

[0102] Therefore, the specific shape of fin 2 is improved. Please refer to one embodiment of this application. Figure 11 and Figure 12 The fin 2 is a wavy fin 2, and the amplitude of the fin 2 is different in different density regions. Specifically, the outer surface of the flat tube 1 has a fin group 24 located in the windward side region, a fin group 25 in the middle region, and a fin group 26 in the leeward side region, and the amplitude of the fin group 24 in the windward side region, the fin group 25 in the middle region, and the fin group 26 in the leeward side region decreases sequentially.

[0103] In this embodiment, multiple density regions are divided along the airflow direction, and different geometric functions of the flat tube shovel-shaped fins are set for different density regions.

[0104] For example, the heat exchange area can be divided into the windward side area, the middle area, and the leeward side area.

[0105] The fin assembly 24 on the windward side adopts a larger amplitude function, giving the flat tube shovel-shaped fins a stronger flow induction capability. After the air enters the heat exchanger, it undergoes a large-amplitude periodic deflection, causing the mainstream air to generate a lateral velocity component, increasing the contact between the air and the surface of the fins 2, and rapidly disrupting the thermal boundary layer in the inlet region.

[0106] The fin group 25 in the middle region adopts a moderate amplitude function to reduce continuous pressure loss while maintaining a certain disturbance capability.

[0107] The fin group 26 in the leeward side region adopts a smaller amplitude function, so that the air can be discharged more smoothly after sufficient heat exchange, reducing the local eddy current and pressure recovery loss in the outlet area.

[0108] As an example, the centerline of a flat tube shovel-shaped fin can be defined as: y=Aif(x) Where Ai is the amplitude parameter of the i-th region; f(x) is the basic waveform function.

[0109] Different regions meet the following requirements: A1>A2>A3 Wherein, A1 is the amplitude of fin 2 in fin group 24 in the windward region, A2 is the amplitude of fin 2 in fin group 25 in the middle region, and A3 is the amplitude of fin 2 in fin group 26 in the leeward region.

[0110] For example: Windward side region: y = A1sin(2πx / λ) Intermediate region: y = A²sin(2πx / λ) Leeward region: y = A3sin(2πx / λ) By changing the A value, different regions can have different disturbance intensities.

[0111] This means that when air enters the heat exchanger, due to its high velocity and thin boundary layer, appropriately enhancing turbulence can significantly improve heat transfer performance. Large-amplitude flat-tube shovel-shaped fins can cause a more pronounced deflection of the airflow, increasing lateral mixing and simultaneously increasing the local velocity gradient, leading to rapid renewal of the thermal boundary layer.

[0112] However, if the entire heat exchanger adopts a large-amplitude structure, it will lead to an increase in overall flow resistance, difficulty in pressure recovery in the outlet area, and an increase in fan power consumption.

[0113] Therefore, this scheme sets a large amplitude structure in the fin group 24 on the windward side, adopts a moderate transition amplitude in the fin group 25 in the middle area, and reduces the amplitude in the fin group 26 on the leeward side, thereby achieving a balance between enhancing heat transfer and reducing pressure drop.

[0114] In practical applications, in the structure of traditional flat tube shovel-shaped fins, the same column or adjacent rows of fins 2 usually maintain the same flow direction position, that is, the peaks and troughs of multiple fins 2 correspond to each other, and the air easily forms a stable channel, which is not conducive to increasing heat exchange efficiency.

[0115] Therefore, regarding the arrangement of fins 2, please refer to one embodiment of this application. Figure 11 , Figure 12 and Figure 13 Along the airflow direction x, the fins 2 in adjacent fin groups 20 are arranged alternately.

[0116] In this embodiment, as Figure 13 As shown, the fins 2 in different rows have flow direction offsets, creating an interlaced structure between adjacent rows of fins 2. For example: The 2d position of the first row of fins: x = x0 + Δx Second row of fins, position 2e: x=x0 Where Δx is the flow direction misalignment distance.

[0117] Because of the misalignment of adjacent rows of fins 2, the wake formed after the air passes through the first row of fins 2d in one fin group 26 will not directly enter the next row of the same position in another fin group 24, but will be subject to new disturbances from the second row of fins 2e in another fin group 24.

[0118] Therefore, this design helps to reduce the formation of stable flow channels, enhance lateral mixing, and improve fluid exchange between different rows of fins. Compared to traditional regular arrangement structures, this design increases the complexity of air movement paths, causing the boundary layer to be constantly re-perturbed. Especially for heat exchangers with flat tube shovel-fin type fins, since the fins 2 themselves have a periodic bending structure, the staggered arrangement can cause different phase perturbations in different rows of fins 2.

[0119] As an example, you can set: Δx = (0.1~0.5)λ Where: λ is the wavelength of the fin.

[0120] When Δx is small, a weak misalignment structure can be formed; when Δx increases, a distinct crossflow channel can be formed.

[0121] Preferably, this misaligned structure can be combined with a variable density structure along the flow direction. For example, the fin assembly 24 on the windward side adopts a combination of high density, large amplitude, and small misalignment; the fin assembly 26 on the leeward side adopts a combination of low density, small amplitude, and large flow space. In this way, a triple regulation structure of density, waveform, and arrangement is formed, further improving heat exchange efficiency.

[0122] In practical applications, traditional flat tube fins with a uniform thickness are typically designed. However, in actual heat exchange processes, the heat transfer tasks undertaken by fins 2 in different areas vary, resulting in differences in the heat exchange effect of fins 2 in different areas.

[0123] For the specific structure of fin 2, please refer to one embodiment of this application. Figure 14 The thickness of fin 2 in fin group 20 on the windward side is greater than that in fin group 20 on the leeward side. For example, the thickness of fin 2 in fin group 20 on the windward side is thicker, while the thickness of fin 2 in fin group 20 on the leeward side is thinner.

[0124] As an example, the thickness ti of the i-th row of fins 2 satisfies: t1 ≠ t2 ≠ t3. For example: t2 > t1 > t3 Therefore, the thickness of fin 2 directly affects its thermal conductivity, stiffness, air passage area, and local resistance. In the windward region of the heat exchanger, where the air temperature difference is large, increasing the thickness of fin 2 enhances thermal conductivity, allowing heat to be transferred quickly to the air side. In the leeward region, the main issue is pressure recovery; therefore, reducing the thickness of fin 2 increases the effective flow area and reduces resistance.

[0125] In summary, the heat exchanger provided in this application, by adding waveform function differences, inter-row staggered structures, and fin thickness gradients, elevates the flow-direction variable-density flat tube shovel-shaped fins from a single-density optimization structure to a multi-parameter spatial control structure. This structure can achieve comprehensive optimization of inlet enhancement, efficient heat exchange in the middle, and low-resistance discharge at the outlet, based on local requirements during airflow.

[0126] In addition, in the embodiments of this application, the heat exchanger with fins 2 arranged with varying density along the flow direction can preferably be structurally designed according to the following steps.

[0127] The first step is to determine the overall dimensions of the heat exchanger. Based on the product installation space, determine the length, width, and thickness of the flat tube 1, as well as the effective flow direction length Lf of the fins 2.

[0128] The second step is to determine the reference fin spacing P0. The reference fin spacing P0 can be determined based on the traditional equal-spacing structure, processing capability, allowable pressure drop, and target heat transfer capacity. For example, for a small air-cooled condenser, P0 can be taken as 1.5 mm to 3.0 mm.

[0129] The third step is to determine the number of density zones, N. If the product structure is simple and the processing cost requirements are high, a two-section structure can be used; if more precise heat exchange and pressure drop matching are required, a three-section or multi-section structure can be used. Generally, N is preferably 2 to 6.

[0130] The fourth step is to determine the length Li of each density region. The length of each section can be determined based on the development trend of the air-side boundary layer, the distribution of heat exchange demand, and the duct structure. For example, for a structure with a sparse front and a dense rear, the low-density region at the front can occupy 0.30Lf to 0.60Lf, and the high-density region at the rear can occupy 0.40Lf to 0.70Lf. For a structure with a sparse-dense-sparse ratio, the high-density region in the middle can occupy 0.30Lf to 0.60Lf.

[0131] Step 5: Determine the fin spacing Pi for each density region. Pi should satisfy: Pmin≤Pi≤Pmax Among them, Pmin is used to avoid fin 2 being too dense, and Pmax is used to avoid fin 2 being too sparse. Adjacent sections should also satisfy the following: 0.5≤Di+1 / Di≤2.0 To avoid drastic changes in density.

[0132] Step 6: Determine whether to set a transition zone. The transition zone length Lt can be between 0.02Lf and 0.20Lf.

[0133] Step 7: Establish a 3D model. For piecewise constant density structures, fins 2 can be generated separately in each flow direction segment using array commands; for continuously varying structures, the continuous function can be discretized into multiple small segments, and then different array spacings can be set for each segment.

[0134] The eighth step involves conducting flow and heat transfer sample tests. Based on the results of air-side pressure drop, heat transfer, surface temperature distribution, and local flow velocity distribution, the components of Pi, Li, and N are adjusted to achieve optimal overall performance of the structure.

[0135] Through the above design method, the variable density finned heat exchanger provided in this application embodiment can be designed in series according to different product sizes and operating conditions, rather than being fixed to a single density arrangement.

[0136] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A heat exchanger, characterized in that, include: A flat tube (1) has an outer surface for heat exchange with air; Multiple rows of fins (2) are arranged in different densities along the air flow direction to form multiple fin groups (20); the fins (2) are wavy fins (2), the fin (2) in the multiple fin groups (20) decrease in amplitude along the air flow direction, and the fin (2) in the multiple fin groups (20) also decrease in thickness. Multiple fin groups (20) are sequentially arranged on the outer surface of the flat tube (1) along the air flow direction, so that air can flow sequentially from adjacent fins (2) through different density regions. The density of the fins (2) in the fin group (20) satisfies a smooth gradient relationship. Along the direction of air flow, the fins (2) in adjacent fin groups (20) are arranged in an alternating pattern.

2. The heat exchanger according to claim 1, characterized in that, The plurality of fin groups (20) include a fin group (21) in a low-density region and a fin group (22) in a high-density region. The fin group (21) in the low-density region and the fin group (22) in the high-density region are arranged sequentially on the outer surface of the flat tube (1) along the air flow direction.

3. The heat exchanger according to claim 1, characterized in that, The plurality of fin groups (20) include a fin group (21) in a low-density region and a fin group (22) in a high-density region. The fin group (22) in the high-density region and the fin group (21) in the low-density region are arranged sequentially on the outer surface of the flat tube (1) along the air flow direction.

4. The heat exchanger according to claim 1, characterized in that, The plurality of fin groups (20) include a first low-density region fin group (21a), a second low-density region fin group (21b), and a high-density region fin group (22). The first low-density region fin group (21a), the high-density region fin group (22), and the second low-density region fin group (21b) are sequentially arranged on the outer surface of the flat tube (1) along the air flow direction.

5. The heat exchanger according to claim 1, characterized in that, The plurality of fin groups (20) include a first high-density region fin group (22a), a second high-density region fin group (22b), and a low-density region fin group (21). The first high-density region fin group (22a), the low-density region fin group (21), and the second high-density region fin group (22b) are sequentially arranged on the outer surface of the flat tube (1) along the air flow direction.

6. The heat exchanger according to claim 1, characterized in that, The plurality of fin groups (20) include a fin group (21) in a low-density region, a fin group (23) in a medium-density region, and a fin group (22) in a high-density region. The fin group (21) in the low-density region, the fin group (23) in the medium-density region, and the fin group (22) in the high-density region are arranged sequentially on the outer surface of the flat tube (1) along the air flow direction. Alternatively, the fin group (22) in the high-density region, the fin group (23) in the medium-density region, and the fin group (21) in the low-density region are sequentially arranged on the outer surface of the flat tube (1) along the airflow direction.

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