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, the flat tube comprises an upper channel, a lower channel and a partition plate, the upper channel is used for main flow and condensation heat exchange of fluid, the lower channel is used for collecting liquid fluid filtered from the upper channel, the partition plate is arranged between the upper channel and the lower channel, the partition plate is provided with a liquid guiding structure, and the liquid guiding structure is used for guiding liquid fluid in the upper channel to the lower channel. The application solves the problem that liquid film is formed by mixing of gas phase and liquid phase condensation in the existing flat tube, the heat exchange wall surface is covered, the condensation heat exchange thermal resistance is increased, and the heat exchange efficiency is affected.

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] Existing refrigerator, air conditioner, and heat pump systems commonly use microchannel flat tubes or porous flat tubes, which mostly employ multiple parallel channels of equal size. After entering through the inlet, the refrigerant flows linearly along each microchannel and completes condensation and heat exchange. This type of structure has advantages such as compact size, large heat exchange area, and mature manufacturing process.

[0003] In traditional porous flat tubes, the aperture, height, and width of each channel are usually kept consistent, and the refrigerant completes gas phase cooling, two-phase condensation, and liquid phase subcooling simultaneously in the same channel.

[0004] However, the liquid refrigerant generated during condensation typically coexists with the gas phase in the same channel in the form of a liquid film, droplets, plugs, or annular liquid films. This means that within the same channel of a flat tube, the gas and liquid phases mix and flow, easily condensing to form a liquid film that covers the heat exchange wall. As the thickness of this liquid film increases, heat from the wall needs to pass through a thicker liquid layer to be transferred to the bulk refrigerant, leading to increased condensation heat transfer thermal resistance and ultimately affecting the overall heat exchange efficiency. Summary of the Invention

[0005] The purpose of this application is to provide a heat exchanger to solve the technical problem that existing flat tubes are prone to gas-liquid phase mixing and condensation to form a liquid film that covers the heat exchange wall, resulting in increased condensation heat exchange thermal resistance and affecting heat exchange efficiency.

[0006] To achieve the above objectives, the technical solution adopted in this application is as follows: This application provides a heat exchanger, including a flat tube, wherein the flat tube includes an upper channel, a lower channel, and a partition plate; The upper channel is used for the main flow of fluid and condensation heat exchange; The lower channel is used to collect liquid fluid filtered from the upper channel; The partition plate is disposed between the upper channel and the lower channel, and the partition plate has a liquid guiding structure for guiding the liquid fluid in the upper channel to the lower channel.

[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 redesigns the internal channel structure of the flat tube. An upper channel, a lower channel, and a partition plate are arranged inside the flat tube. The upper channel is mainly used for the main flow and condensation heat exchange of fluids such as refrigerant, while the lower channel is mainly used to collect and discharge the liquid refrigerant formed during the condensation process in the upper channel, thereby reducing the accumulation of liquid film on the main heat exchange wall surface. The partition plate is set between the upper and lower channels. Utilizing the liquid guiding structure on the partition plate, the condensate formed on the wall surface of the upper channel is guided to the lower channel, effectively reducing the thickness of the liquid film on the wall surface of the upper channel. This allows heat to be efficiently transferred to the refrigerant bulk without having to pass through a thick liquid layer, thus solving the problem of increased thermal resistance caused by the condensate film covering the wall surface and ensuring overall heat exchange efficiency.

[0008] In one embodiment, the liquid guiding structure is improved, the liquid guiding structure includes liquid guiding holes disposed on the partition plate and multiple liquid collecting grooves, the liquid guiding holes being opened at the bottom of the liquid collecting grooves and distributed at intervals.

[0009] The above technical solution has the following advantages or beneficial effects: The liquid collection tank forms a low-lying convergence area on the partition plate. When condensate forms on the wall of the upper channel, surface tension pulls the liquid film and draws it into the collection tank, from where it drains into the lower channel through the guide holes at the bottom of the tank. This helps to shorten the residence time of the liquid film on the heat exchange wall, reduce the increase in thermal resistance caused by liquid film thickening, and thus improve the overall heat exchange efficiency.

[0010] In one embodiment, the liquid collection tank is any one of a V-shaped tank, a U-shaped tank, or an arc-shaped tank.

[0011] The above technical solution has the following advantages or beneficial effects: The liquid collection tank adopts a gradient structure with a wide opening and a narrow bottom, creating strong capillary force at the bottom. This capillary action can tear and peel off the continuous liquid film adhering to the main heat exchange wall, rapidly reducing the thickness of the liquid film on the wall and thus improving the overall condensation heat exchange efficiency.

[0012] In one embodiment, the liquid collection tanks extend along the length of the flat tube and are spaced apart on the partition plate in the width direction of the flat tube, with protrusions formed between adjacent liquid collection tanks.

[0013] The above technical solution has the following advantages or beneficial effects: Multiple condensate collection channels are spaced apart on the partition plate, which means that the width of the flat tube is divided into multiple parallel condensate collection and drainage units. This allows the condensate collection channels on both sides of each boss to independently collect the condensate from the corresponding area of ​​the wall and drain it into the lower channel through the liquid guide holes at their bottoms, thereby improving the overall heat exchange consistency of the flat tube.

[0014] In one embodiment, the liquid guiding structure further includes a porous liquid suction core, which is disposed in the liquid collection groove and located above the liquid guiding hole, with both sides of the porous liquid suction core abutting against the boss.

[0015] The above technical solution has the following advantages or beneficial effects: The porous wick absorbs the condensate in the upper channel and directs it into the lower channel, thus forming an active wicking structure. This effectively reduces the liquid film thickness and thermal resistance, thereby improving heat exchange efficiency.

[0016] In one embodiment, the structure of the lower channel is improved, wherein the entrance end of the lower channel is closed, semi-closed, or equipped with a flow-limiting structure.

[0017] The above technical solution has the following advantages or beneficial effects: By designing the inlet structure of the lower channel to be closed or equipped with a flow-limiting structure, it is beneficial to block the bypass path of gas entering the lower channel, ensuring that most of the superheated gas can enter the upper channel. This ensures that the wall of the upper channel has sufficient gas flow to meet the strong heat exchange demand on the air-side windward side, thereby improving the overall effective volume utilization rate of the flat tube.

[0018] The internal structure of the flat tube is improved, and the outlet end of the flat tube is provided with a confluence cavity that connects the upper channel and the lower channel. The partition plate extends to the confluence cavity and stops. The confluence cavity is used to allow the gas-liquid phase mixture in the upper channel to merge with the liquid fluid in the lower channel.

[0019] The above technical solution has the following advantages or beneficial effects: By adding a manifold to the flat tube, the upper and lower channels are recoupled at the outlet end, allowing residual liquid film or droplets accumulated at the end of the upper channel to merge and be discharged from the liquid fluid in the manifold and the lower channel. This effectively eliminates the residual liquid film and droplets at the end of the upper channel, achieving wall drying at the end of the heat exchange process and ensuring overall heat exchange efficiency.

[0020] In one embodiment, the height of the upper channel is greater than the height of the lower channel.

[0021] The above technical solution has the following advantages or beneficial effects: Allocating most of the height space inside the flat tube to the upper channel that undertakes the main heat exchange allows the gas phase in the inlet superheated and front high dryness zone to have ample flow area. While ensuring the intensity of turbulent heat transfer, this helps to reduce local flow velocity and reduce equipment power consumption.

[0022] The internal structure of the upper and lower channels is improved. Both the upper and lower channels are equipped with multiple vertical partitions, which divide the upper and lower channels into multiple guide channels corresponding to the upper and lower positions. The width of the multiple guide channels gradually decreases from the windward side to the leeward side of the flat tube.

[0023] The above technical solution has the following advantages or beneficial effects: Having a larger channel width in the guide channel near the windward side is beneficial for increasing the fluid ratio in the high-efficiency heat exchange zone; having a smaller channel width in the guide channel near the leeward side is used to reduce the hydraulic diameter and increase the heat exchange intensity on the local refrigerant side.

[0024] In one embodiment, the inner wall of the flow guiding channel is provided with ribs extending along the length direction of the flow guiding channel, and the ribs are arranged at intervals on the inner wall of the flow guiding channel.

[0025] The above technical solution has the following advantages or beneficial effects: By utilizing the ribs on the inner wall of the flow channel, the liquid film formed on the main heat exchange wall surface in the upper channel cannot maintain a stable and continuous covering layer, but is instead segmented by the ribs. This helps to reduce the liquid phase coverage area, shortens the heat conduction path through the liquid layer, and effectively improves the problem of increased thermal resistance caused by liquid film thickening. Attached Figure Description

[0026] 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.

[0027] Figure 1 A three-dimensional structural schematic diagram of the flat tube of the heat exchanger provided in the embodiment of this application; Figure 2 A magnified view of a partial structure of the flat tube provided in the embodiments of this application. Figure 1 ; Figure 3 A magnified view of a partial structure of the flat tube provided in the embodiments of this application. Figure 2 ; Figure 4 Enlarged schematic diagram of the internal structure of the flat tube provided in the embodiments of this application Figure 1 ; Figure 5 Enlarged schematic diagram of the internal structure of the flat tube provided in the embodiments of this application Figure 2 ; Figure 6This is an exploded schematic diagram of the liquid guiding structure on the partition plate provided in the embodiments of this application; Figure 7 A schematic diagram of the exploded structure of the outlet end of the flat tube provided in an embodiment of this application; Figure 8 A schematic diagram of the internal structure of the outlet end of the flat tube provided in an embodiment of this application; Figure 9 This is an orthographic projection view of the internal structure of the flat tube provided in an embodiment of this application; Figure 10 Enlarged schematic diagram of the internal structure of the flat tube provided in the embodiments of this application Figure 3 .

[0028] The following are the labeling elements in the figure: 1-Upper passage; 2-Lower level passage; 3-Separator; 4-Liquid guiding structure; 41-Liquid guiding hole; 42-Liquid collecting groove; 43-Boss; 44-Porous liquid suction core; 5-Manifold; 61-Vertical partition; 62-Flow channel; 63-Rib. Detailed Implementation

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] In traditional flat tubes, the gas and liquid phases typically mix and flow within the same channel, and the condensed liquid film easily covers the heat exchange wall. As the liquid film thickness increases, heat from the wall needs to pass through a thicker liquid layer to be transferred to the bulk refrigerant, leading to increased thermal resistance during condensation and affecting heat exchange efficiency. Furthermore, condensate tends to accumulate within the channel, potentially forming localized liquid plugs or thick liquid films, resulting in reduced cross-sectional area for gas flow, increased localized pressure drop, and decreased flow stability.

[0034] In related technologies, there are heat exchanger structures that separate the channels within a flat tube. This technology uses partition plates to divide the interior of the flat tube into upper and lower regions, but it is essentially a traditional spatial division structure. The partition plates are solid dividers, ensuring that the upper and lower channels are independent of each other. There is no fluid communication between the upper and lower channels, no process of liquid refrigerant moving from one channel to another, and no mechanism for condensate collection and active drainage. This technology mainly addresses how to improve the internal structural strength of the flat tube, increase support, and facilitate disassembly and maintenance; it cannot solve the problem of heat exchange deterioration caused by liquid film coverage during condensation.

[0035] It is evident that the existing flat tubes lack dedicated channels for liquid collection, conduction, and drainage, making it difficult to promptly remove condensate from the main condensation heat exchange zone, resulting in condensate accumulation and affecting heat exchange efficiency.

[0036] Therefore, this application provides a novel heat exchanger that redesigns the internal structure of the flat tube without altering its finned side structure. The flat tube is divided into upper and lower double-layer channels, with a partition plate between them. A liquid-guiding structure on the partition plate guides the liquid fluid in the upper channel to the lower channel, thus separating the liquid fluid from the main flow path in the upper layer. This ensures the overall heat exchange efficiency of the heat exchanger and solves the problem of traditional flat tubes where gas and liquid phases easily mix and condense, forming a liquid film that covers the heat exchange wall, leading to increased condensation heat transfer resistance and affecting heat exchange efficiency. A detailed description follows.

[0037] The flat tube structure provided in this application embodiment can be applied to flat tube shovel-type condensers, refrigerator condensers, air conditioner condensers or heat pump condensers, which is beneficial to increase the heat exchange per unit volume in a limited space, thereby reducing the air-side thermal resistance and improving the overall energy efficiency.

[0038] Please see Figure 1 The heat exchanger includes at least a flat tube, the body of which is a flat tubular structure extending along the refrigerant flow direction, and its exterior can be fitted with shoveled fins or other air-side heat exchange structures. The interior of the flat tube includes an upper channel 1, a lower channel 2, and a partition plate 3.

[0039] The upper channel 1 is located inside the flat tube, near the upper wall, and is directly connected to the refrigerant inlet of the equipment. After entering through the inlet, the superheated gaseous refrigerant, due to its lower density, mostly enters the upper channel 1, where it gradually undergoes gas-phase cooling and condensation heat exchange. The upper channel 1 is used for the main flow of the fluid and condensation heat exchange. This "fluid" can be hot gaseous refrigerant, saturated gaseous refrigerant, or a gas-liquid two-phase refrigerant, primarily a gas-liquid mixture, with the upper channel 1 serving as the main flow channel for these gas-liquid mixtures.

[0040] The lower channel 2 is located below the upper channel 1 and is used to collect the liquid fluid filtered from the upper channel 1. This "liquid fluid" is mainly the liquid refrigerant formed during the condensation process, thereby reducing the accumulation of liquid film on the main heat exchange wall surface of the upper channel 1. Therefore, the lower channel 2 does not serve as a flow channel for the aforementioned gas-liquid mixture, but rather as a means to collect and discharge the liquid fluid formed in the upper channel 1.

[0041] The partition plate 3 is disposed between the upper channel 1 and the lower channel 2. The partition plate 3 can preferably be made of aluminum alloy material that is the same as or similar to the flat tube body, and can be integrally formed, extruded, brazed or welded to the flat tube body to ensure heat conduction, pressure bearing and integral forming performance.

[0042] Please refer to the following: Figure 1 and Figure 2 The partition plate 3 has a liquid guiding structure 4, which is used to guide the liquid fluid in the upper channel 1 to the lower channel 2. This means that after the condensate forms on the wall of the upper channel 1, it flows through the liquid guiding structure 4 on the partition plate 3 and is then guided into the lower channel 2, effectively directing the liquid refrigerant that is gradually generated during the condensation process.

[0043] Compared with the prior art, the heat exchanger provided in this embodiment redesigns the internal channel structure of the flat tube. An upper channel 1, a lower channel 2, and a partition plate 3 are arranged inside the flat tube. The upper channel 1 is mainly used for the main flow and condensation heat exchange of fluids, such as superheated gaseous refrigerant, saturated gaseous refrigerant, and gas-liquid two-phase refrigerant. The lower channel 2 is mainly used to collect and discharge the liquid refrigerant formed during the condensation process in the upper channel 1, thereby reducing the accumulation of liquid film on the main heat exchange wall surface. The partition plate 3 is disposed between the upper channel 1 and the lower channel 2. Using the liquid guiding structure 4 on the partition plate 3, the condensate formed on the wall surface of the upper channel 1 is guided to the lower channel 2, effectively reducing the thickness of the liquid film on the wall surface of the upper channel 1. This allows heat to be efficiently transferred to the refrigerant bulk without having to pass through a thick liquid layer, thus solving the problem of increased thermal resistance caused by the condensate film covering the wall surface and ensuring overall heat exchange efficiency.

[0044] In this way, after the condensate is separated from the upper channel 1, the accumulation of liquid refrigerant in the upper channel 1 is avoided to form a local liquid plug or thick liquid film, ensuring that the gas phase flow area is not significantly reduced, thereby effectively reducing the local flow resistance, improving the stability of gaseous refrigerant flow, and solving the drawbacks of increased pressure drop and decreased flow stability in traditional structures.

[0045] The upper channel 1 is dedicated to the main flow and condensation of superheated or saturated gaseous refrigerant, while the liquid phase is isolated to the lower channel, making the flow distribution along the refrigerant side more reasonable. Combined with the characteristics of strong upwind heat transfer and weak leeward heat transfer on the air side, this gas-liquid separation design helps to maintain a high gas phase flow velocity and heat transfer coefficient in the channel, thereby better adapting to the uneven heat transfer capacity along the air side and improving the overall heat transfer efficiency.

[0046] As can be seen, the heat exchanger provided in this application embodiment, without changing the external fin structure of the flat tube, only reconstructs the internal structure of the flat tube in a double layer. This retains the advantages of the original flat tube, such as compact size, large heat exchange area, and mature processing, while ensuring pressure resistance and thermal conductivity through the integrated partition plate 3. This achieves a unity of functional separation and structural strength, effectively enhancing the overall heat exchange performance.

[0047] For the specific configuration of the liquid guiding structure 4, please refer to one embodiment of this application. Figure 2 , Figure 3 and Figure 4 The liquid guiding structure 4 includes liquid guiding holes 41 and multiple liquid collecting tanks 42 disposed on the partition plate 3. The liquid guiding holes 41 are opened at the bottom of the liquid collecting tanks 42 and are spaced apart. In other embodiments, liquid guiding slits or micropore arrays may also be opened at the bottom of each liquid collecting tank 42. After the condensate forms on the wall of the upper channel 1, it first collects in the liquid collecting tanks 42, and then enters the lower channel 2 through the liquid guiding holes 41.

[0048] Therefore, the liquid collection tank 42 is not a simple plane, but rather forms a low-lying confluence area on the partition plate 3. When condensate forms on the wall of the upper channel 1, surface tension pulls the liquid film and draws it into the liquid collection tank 42, from where it flows down to the lower channel 2 through the liquid guide holes 41 at the bottom of the tank. This design actively breaks up and cuts off the liquid film on the heat exchange wall of the upper channel 1, preventing the liquid film from continuously thickening on the wide wall surface. Compared to the slow flow down by gravity alone, this structure significantly shortens the residence time of the liquid film on the heat exchange wall, reduces the increase in thermal resistance caused by liquid film thickening, and thus improves the overall heat exchange efficiency.

[0049] Furthermore, the liquid guide holes 41 are spaced out rather than continuously slit in the liquid collection tank 42. These spaced, independent holes ensure liquid passage while effectively preventing large-scale gas flow through using liquid seals or orifice throttling effects, thus maintaining pressure stability in the upper channel 1. Additionally, the spaced liquid guide holes 41 allow liquid generated from condensation in each section to be discharged promptly in the nearest area, preventing long-distance accumulation of condensate along the flow direction. This effectively avoids localized liquid blockage caused by liquid accumulation at the end of the flow path, as is common in traditional structures, thereby reducing localized flow resistance.

[0050] For the specific structure of the liquid collection tank 42, please refer to the embodiments of this application. Figure 4 The width of the liquid collecting tank 42 gradually decreases from the opening to the bottom. The liquid collecting tank 42 can preferably be any one of a V-shaped tank, a U-shaped tank, or an arc-shaped tank. This means that the opening of the liquid collecting tank 42 faces into the upper channel 1, thus forming a funnel-shaped guide structure.

[0051] Therefore, the liquid collection tank 42 adopts a gradually narrowing structure with a wide opening and a narrow bottom, creating a strong capillary force at the bottom. When the condensate on the upper wall comes into contact with the opening, the narrowed cross-section generates a surface tension gradient, actively drawing the liquid film from both sides of the wall to the bottom. This active capillary action can tear and peel off the continuous liquid film adhering to the main heat exchange wall, rapidly reducing the thickness of the liquid film on the wall and thus improving the overall condensation heat exchange efficiency.

[0052] The liquid collection tank 42, employing a V-shaped, U-shaped, or arc-shaped groove, exhibits a streamlined, gradually changing contour. When high-speed gaseous refrigerant flows in the upper channel 1, this smooth groove structure minimizes airflow disturbance and prevents eddies or sudden increases in localized resistance. Simultaneously, the liquid collected at the bottom of the collection tank 42 is accelerated by the constricted structure and discharged into the lower channel 2 through the bottom guide hole 41. Therefore, the shape of the collection tank 42 effectively prevents condensate from stagnating or forming suspended droplets within the tank, effectively suppressing flow oscillations caused by severe disturbances at the gas-liquid interface, thus solving the problems of increased pressure drop and decreased flow stability.

[0053] Furthermore, the liquid collection tank 42 adopts a funnel-shaped constricted structure, forming a liquid seal barrier at the bottom of the tank. When a small amount of condensate accumulates at the bottom, the liquid fills the liquid guide hole 41, making it difficult for the gas phase of the upper channel 1 to penetrate into the lower channel 2. This design of the liquid collection tank 42 helps ensure that the liquid guide hole 41 allows only unidirectional liquid passage, effectively preventing ineffective leakage of gaseous refrigerant in the upper channel 1, thereby ensuring the purity and flow rate of the gas phase in the upper channel 1.

[0054] Based on the above, please refer to the embodiments in this application as well. Figure 4 and Figure 5 The liquid collection tank 42 extends along the length of the flat tube and is arranged at intervals on the partition plate 3 in the width direction of the flat tube, with protrusions 43 formed between adjacent liquid collection tanks 42.

[0055] In this embodiment, the partition plate 3 has multiple liquid collection grooves 42 extending along the length direction of the flat tube. The liquid collection grooves 42 are arranged at intervals on the partition plate 3, and there are protruding bosses 43 between adjacent liquid collection grooves 42.

[0056] Preferably, the inner wall of the upper channel 1 is connected to the boss 43, meaning that the bosses 43 on both sides can directly connect to the inner wall surfaces of the upper channel 1. When a condensate film forms on the inner wall surface of the upper channel 1, under the action of surface tension and gravity, the liquid film on the wall surface will flow to the nearest boss 43, and then quickly flow downwards along the side wall of the boss 43 to the bottom of the adjacent collection tank 42, and drain into the lower channel 2 from the liquid guide hole 41 at the bottom of the collection tank 42. This provides the shortest vertical discharge path for the liquid film, efficiently peeling off the liquid film from the wall surface, thereby significantly reducing the average liquid film thickness.

[0057] Thus, multiple liquid collection grooves 42 are arranged at intervals on the partition plate 3, which means that multiple parallel liquid collection and drainage units are divided in the width direction of the flat tube. This allows the liquid collection grooves 42 on both sides of each boss 43 to independently collect condensate from the corresponding area of ​​the wall and drain it into the lower channel 2 through the liquid guide holes 41 at their bottoms. This design helps to eliminate the drawback of localized condensate accumulation on one side in traditional structures, enabling the liquid film distribution on the refrigerant side to accurately match the non-uniform heat transfer intensity on the air side from the windward to the leeward side, effectively improving the overall heat transfer consistency of the flat tube.

[0058] Furthermore, since the protrusions 43 on both sides of the upper channel 1 can connect to the inner walls of the upper channel 1 and are alternately distributed with the liquid collection tank 42, this means that multiple narrow-section parallel sub-channels extending along the length direction are naturally divided on the partition plate 3 at the bottom of the upper channel 1. These protrusions 43 play a role in rectifying and constraining the high-speed gas phase, effectively suppressing the lateral swaying and violent disturbance of the gas-liquid two-phase flow in the wide and flat tube. At the same time, since the condensate is promptly guided away by the liquid guiding structure 4, the liquid level at the bottom of each sub-channel is low, ensuring that the mainstream gas phase has a stable and sufficient flow area, avoiding the acceleration or blockage of the airflow caused by the liquid phase occupying the cross section, thereby effectively reducing the local frictional pressure drop and helping to eliminate the slug flow instability caused by large-scale liquid plugs.

[0059] In practical applications, the liquid film on the wall of the upper channel 1 must accumulate to a certain thickness before it can slowly flow into the bottom of the collection tank 42 and be discharged through the guide hole 41 by gravity or airflow. This drainage mechanism has a slow response speed, and during this period, the liquid film still covers the wall and forms thermal resistance, which affects the heat exchange efficiency.

[0060] Therefore, the above-mentioned liquid guiding structure 4 is further improved. Please refer to one embodiment of this application. Figure 4 and Figure 6 The liquid guiding structure 4 also includes a porous liquid suction core 44, which is disposed in the liquid collection tank 42 and located above the liquid guiding hole 41. The two sides of the porous liquid suction core 44 abut against the protrusions 43 located on both sides of the liquid collection tank 42, and the protrusions 43 on both sides are used to fix the porous liquid suction core 44.

[0061] The porous liquid-absorbing core 44 can preferably be made of any one of the following: metal wire mesh, sintered porous aluminum, aluminum foam, or metal fiber felt, or other porous metal materials with capillary liquid absorption capacity. Specifically, the average pore size of the porous liquid-absorbing core 44 is preferably 20μm-200μm, the porosity is 40%-85%, and its thickness is preferably 0.05 mm-0.50 mm.

[0062] As can be seen, previously the liquid film needed to accumulate to a certain thickness before flowing down along the protrusion 43. However, the porous liquid-absorbing core 44 has a micron-sized pore size of 20μm-200μm, and the strong capillary force it can generate is far greater than gravity. When the porous liquid-absorbing core 44 is pressed tightly against the sidewall of the protrusion 43, it is equivalent to setting up a liquid-absorbing structure in the path of the liquid film. This allows the condensate that has not yet thickened on the inner wall of the upper channel 1 to be instantly drawn into the porous liquid-absorbing core 44 and quickly guided to the liquid-guiding hole 41 for discharge.

[0063] In this way, the porous wick 44 absorbs the condensate in the upper channel 1 and guides the condensate into the lower channel 2, thus forming an active wicking structure. This allows the heat exchange wall of the upper channel 1 to remain in a near-dry state for a long time, effectively reducing the liquid film thickness and thermal resistance, thereby improving heat exchange efficiency.

[0064] Furthermore, although the funnel-shaped liquid collection tank 42 in the previous liquid guide hole 41 has a liquid sealing function, the gas phase may still penetrate under high pressure differential. In this embodiment, a porous liquid suction core 44 is provided in the liquid collection tank 42. After the porous liquid suction core 44 fills the liquid collection tank 42, the micropores on the porous liquid suction core 44 form a one-way channel, ensuring that only liquid fluid can be transferred downward to the lower channel 2, while the gaseous refrigerant in the upper channel 1 will not leak into the lower channel 2, effectively maintaining the pressure and flow rate of the mainstream gas phase, thereby ensuring a strong scouring heat transfer effect on the air-side windward side.

[0065] Furthermore, for the installation structure of the porous liquid-absorbing core 44, the protrusions 43 on both sides of the liquid collection groove 42 are used to abut and fix the porous liquid-absorbing core 44 from both sides. No welding or adhesive is required; positioning is achieved solely through the existing structure's clamping mechanism. When the flat tube experiences frequent temperature changes, such as thermal expansion and contraction, the metal porous liquid-absorbing core 44 and the aluminum alloy flat tube have similar coefficients of thermal expansion, and the sidewall clamping force allows for slight sliding compensation, preventing loosening and dislocation caused by adhesive aging or thermal stress. This effectively ensures that the porous liquid-absorbing core 44 maintains stable contact throughout its long-term service life, thereby maintaining long-term, highly efficient active liquid absorption performance.

[0066] In practical applications, superheated gas has a lower density and tends to rise at the inlet of the flat tube into the upper channel 1. However, if the inlet of the lower channel 2 is completely open, some high-pressure gas will directly rush into the lower channel 2 due to inertia or pressure fluctuations. Because this gas does not pass through the main condensation heat exchange zone of the upper channel 1, it cannot make full use of the wide wall surface of the upper channel 1 for effective condensation, resulting in waste and affecting heat exchange efficiency.

[0067] Regarding the structure of the lower channel 2, in one embodiment of this application (not shown in the figure), the inlet end of the lower channel 2 is closed, semi-closed, or equipped with a flow-limiting structure (not shown in the figure) to prevent the inlet superheated gas from directly entering the lower channel 2. The "flow-limiting structure" can preferably be a baffle or baffle at the inlet end; any structure that can block the fluid is acceptable, and no specific limitation is made here.

[0068] Therefore, the inlet structure of the lower channel 2 is designed to be closed or have a flow-limiting structure, which helps to block the gas bypass path into the lower channel 2, ensuring that most of the superheated gas can enter the upper channel 1, and ensuring that the wall of the upper channel 1 has sufficient gas flow to meet the strong heat exchange demand of the air-side windward side, thereby improving the overall effective volume utilization rate of the flat tube.

[0069] As can be seen, the internal structure of the flat tube of the heat exchanger provided in this application embodiment has an upper channel 1 as a high-speed gas phase condensation zone and a lower channel 2 as a liquid phase collection and subcooling zone. By limiting the flow at the inlet end of the lower channel 2, the airflow crosstalk between the two channels at the inlet end is effectively cut off, thereby enabling each channel to work normally and ensuring heat exchange efficiency.

[0070] In practical applications, liquid films or slowly moving droplets can easily remain on the wall surface at the outlet end of the upper channel 1. These residual liquid films or droplets will remain in the end corner of the upper channel 1 due to the attenuation of airflow thrust and cannot be removed.

[0071] Therefore, the structure of the flat tube is further improved. Please refer to another embodiment of this application. Figure 7 and Figure 8 The outlet end of the flat tube is provided with a manifold 5 that connects the upper channel 1 and the lower channel 2. The partition plate 3 extends to the manifold 5 and then stops. The manifold 5 is used to allow the gas-liquid phase mixture in the upper channel 1 to merge with the liquid fluid in the lower channel 2.

[0072] In this embodiment, a confluence channel is added at the outlet end of the flat tube. The confluence chamber 5 inside is prematurely terminated by the partition plate 3, forming a confluence chamber 5 that connects the upper channel 1 and the lower channel 2. This means that the gaseous fluid flowing into the confluence chamber 5 from the upper channel 1 merges with the liquid fluid flowing into the confluence chamber 5 from the lower channel 2, effectively eliminating the liquid film and droplets remaining at the end of the upper channel 1, achieving wall drying at the end of the heat exchange process, and ensuring overall heat exchange efficiency.

[0073] As can be seen, a manifold 5 is provided at the outlet end of the entire flat tube, allowing the upper channel 1 and the lower channel 2 to connect. This allows the upper channel 1 to open at the end of the flat tube, resulting in a sudden increase in the cross-sectional area of ​​the flow channel and a sharp decrease in flow velocity. The airflow carrying residual droplets loses kinetic energy at this point. Under the influence of gravity and the downstream airflow, these residual tiny droplets fall directly into the manifold 5 and mix with the liquid phase in the lower channel 2 before being discharged. This achieves wall drying at the end of the heat exchange process, ensuring that the main heat exchange wall maintains a low liquid film coverage state throughout the entire length of the flat tube from inlet to outlet. This effectively reduces the condensation thermal resistance, thereby ensuring the overall heat exchange efficiency.

[0074] Regarding the height settings of the upper channel 1 and the lower channel 2, please refer to one embodiment of this application. Figure 9 and Figure 10 The height of the upper channel 1 is greater than the height of the lower channel 2, and the height hg of the upper channel 1 and the height hl of the lower channel 2 satisfy the following: hg = kh•hl, where kh is 1.2-3.0 In this way, most of the height space inside the flat tube is allocated to the upper channel 1, which undertakes the main heat exchange, so that the gas phase in the inlet superheated and front high dryness zone has sufficient flow area. While ensuring the intensity of turbulent heat transfer, it is beneficial to reduce the local flow velocity, thereby significantly reducing the frictional pressure drop along the flow path caused by high flow velocity and effectively reducing the power consumption of the equipment.

[0075] In other embodiments, the height of the lower channel 2 can be set to be greater than that of the upper channel 1.

[0076] Further improvements have been made to the specific structures of the upper channel 1 and the lower channel 2. Please refer to one embodiment of this application for details. Figure 9 and Figure 10 Both the upper channel 1 and the lower channel 2 are equipped with multiple vertical partitions 61, which divide the upper channel 1 and the lower channel 2 into multiple guide channels 62 corresponding to their vertical positions. For example, Figure 9 As shown, the width of the multiple guide channels 62 gradually decreases from the windward side F1 of the flat tube to the leeward side F2.

[0077] As an example, in this embodiment, the height of the multiple guide channels 62 is consistent, and the width bi of the i-th guide channel 62 satisfies: bi = bmin + (bmax - bmin)(1 - ηi)n Where ηi=(i-1) / (N-1), N is the total number of 62 guide channels, i=1,2,3,...,N, bmax is the maximum channel width of F1 on the windward side, bmin is the minimum channel width of F2 on the leeward side, and n is the width variation index.

[0078] The flow area Ai and hydraulic diameter Dh,i of the i-th guide channel 62 satisfy the following: Ai=bi(hg+hl),Dh,i=2bi(hg+hl) / (bi+hg+hl) Suppose that the upper channel 1 inside the flat tube has N of the aforementioned guiding channels 62, and each guiding channel 62 is numbered i=1,2,3,...,N along the airflow direction from the windward side F1 to the leeward side F2. The dimensionless position of the i-th channel is defined as: ηi=(i-1) / (N-1) In the formula, ηi is the dimensionless position of the i-th channel in the air flow direction. When ηi=0, it indicates that the channel is located on the windward side F1; when ηi=1, it indicates that the channel is located on the leeward side F2.

[0079] Under the condition that the channel height remains substantially unchanged, the width bi of the i-th flow guide channel 62 in the upper layer channel 1 can be determined according to the following rule: bi=bmin+(bmax-bmin)(1-ηi)n In the formula, bi is the width of the i-th flow guide channel 62; bmax is the maximum channel width on the windward side F1; bmin is the minimum channel width on the leeward side F2; n is the width variation index, and n>0.

[0080] When n=1, the width of each flow guide channel 62 decreases approximately linearly from the windward side F1 to the leeward side F2; when n>1, the width in the front section changes relatively gently, and the width reduction near the leeward side F2 is more obvious; when 0<n<1, the width in the front section decreases rapidly, and the variation in the rear section is relatively gentle.

[0081] It can be seen that on the cross section of the flat tube, the multiple flow guide channels 62 in the upper layer channel 1 can be arranged in sequence from the windward side F1 to the leeward side F2 along the air flow direction. The height of each flow guide channel 62 can be kept substantially the same, and the width changes gradually according to a gradient rule, so as to form a gradient variable-aperture structure.

[0082] In this way, the flow guide channels 62 close to the windward side F1 have a relatively large channel width, which is beneficial to increasing the fluid proportion in the high-efficiency heat exchange zone; the flow guide channels 62 close to the leeward side F2 have a relatively small channel width, which is used to reduce the hydraulic diameter and improve the heat exchange intensity on the local refrigerant side.

[0083] In other embodiments (not shown in the drawings), the width of the plurality of flow guide channels 62 may also be set to gradually increase from the windward side F1 to the leeward side F2 of the flat tube.

[0084] On the basis of the above, in one embodiment of the present application, please refer to Figure 10 , the inner wall of each flow guide channel 62 is provided with ribs 63 extending along the length direction of the flow guide channel 62, and these ribs 63 are arranged at intervals on the inner wall of the flow guide channel 62.

[0085] In this way, by utilizing the ribs 63 on the inner wall of the flow guide channel 62, the liquid film formed on the main heat exchange wall surface in the upper layer channel 1 cannot maintain a stable and continuous covering layer, but is divided by the ribs 63. This is beneficial to reducing the liquid phase coverage area, shortening the conduction path of heat passing through the liquid layer, and effectively improving the problem of increased thermal resistance caused by thickened liquid film.

[0086] Working principle of the heat exchanger provided in the embodiments of the present application: During refrigeration system operation, superheated gaseous refrigerant enters through the inlet end of the flat tube. Due to the low gas density, and the fact that the inlet end of the lower channel 2 is closed, semi-closed, or has flow-limiting features, the refrigerant at the inlet end mainly enters the upper channel 1. Because the upper channel 1 has a larger height, it can reduce gas flow resistance and provide a larger condensation heat exchange space.

[0087] As the refrigerant flows along the upper channel 1 and releases heat to the outside air, the superheated gas gradually cools down to saturation and further condenses. The condensate first adheres to the inner wall of the upper channel 1 in the form of droplets or liquid films, especially forming a liquid film near the upper surface of the middle partition plate 3.

[0088] The liquid collection tank 42 on the upper surface of the partition plate 3 can collect the liquid film. Due to the concave structure of the liquid collection tank 42, the condensate tends to flow into the tank under the action of wall wetting, airflow shearing and gravity assistance. The condensate is guided into the lower channel 2 by the liquid guide hole 41 provided at the bottom of the liquid collection tank 42.

[0089] When a porous wick 44 (such as a metal mesh) is used, the porous wick 44 is similar to a metal capillary layer. After the condensate comes into contact with the porous wick 44, it can enter the pores under capillary action and enter the lower channel 2 along the liquid guide hole 41. Due to the small pore size and easy wettability of the pores, the porous wick 44 can actively absorb liquid, effectively increasing the priority of liquid entering the lower channel 2, while inhibiting a large amount of gaseous refrigerant from directly bypassing into the lower channel 2.

[0090] The liquid refrigerant entering the lower channel 2 flows along the length of the flat tube towards the outlet end, where it merges with the remaining two-phase flow or liquid refrigerant in the upper channel 1 at the manifold 5 at the outlet end. As a result, the condensate no longer remains near the main heat exchange wall of the upper channel 1 for an extended period, effectively reducing the thickness of the liquid film coverage, thereby lowering the thermal resistance of the condensate film, and effectively eliminating the liquid film and droplets remaining at the end of the upper channel 1, achieving wall drying at the end of the heat exchange process.

[0091] Meanwhile, multiple flow guide channels 62 are present in the upper channel 1 and lower channel 2 of the flat tube. The width of these multiple flow guide channels 62 gradually decreases from the windward side F1 to the leeward side F2 of the flat tube, thus forming a gradient variable aperture structure. The flow guide channels 62 near the windward side F1 are wider, providing a larger flow area and lower flow resistance, which is beneficial for fully utilizing the strong air-side heat transfer capacity of the windward side F1. The flow guide channels 62 near the leeward side F2 are narrower, resulting in a smaller hydraulic diameter. Under the same or similar mass flow rate conditions, this is beneficial for increasing the local refrigerant velocity and refrigerant-side heat transfer coefficient, thereby compensating for the decrease in air-side heat transfer capacity on the leeward side F2.

[0092] As can be seen, the heat exchanger provided in this application embodiment reduces the liquid film thermal resistance through layered drainage channels, achieves directional drainage of condensate through the combination of liquid collection tank 42 and porous liquid suction core 44, and achieves matching of heat exchange capacity between the air side and the refrigerant side through gradient variable aperture flow channel 62. Under the combination of multiple structural aspects, the overall heat exchange performance and operational stability of the heat exchanger are effectively improved.

[0093] 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 comprising a flat tube, characterized in that, The flat tube includes an upper channel, a lower channel, and a partition plate; The upper channel is used for the main flow of fluid and condensation heat exchange; The lower channel is used to collect liquid fluid filtered from the upper channel; The partition plate is disposed between the upper channel and the lower channel, and the partition plate has a liquid guiding structure, which is used to guide the liquid fluid in the upper channel to the lower channel. The liquid guiding structure includes liquid guiding holes and multiple liquid collecting grooves disposed on the partition plate. The liquid guiding holes are opened at the bottom of the liquid collecting grooves and are spaced apart. The liquid guiding structure also includes a porous liquid suction core, which is disposed in the liquid collection tank and located above the liquid guiding hole.

2. The heat exchanger according to claim 1, characterized in that, The liquid collection tank can be any one of a V-shaped tank, a U-shaped tank, or an arc-shaped tank.

3. The heat exchanger according to claim 1, characterized in that, The liquid collection tanks extend along the length of the flat tube and are spaced apart on the partition plate along the width of the flat tube, with protrusions formed between adjacent liquid collection tanks.

4. The heat exchanger according to claim 1, characterized in that, The entrance end of the lower channel is closed, semi-closed, or equipped with a flow-limiting structure.

5. The heat exchanger according to claim 1, characterized in that, The outlet end of the flat tube is provided with a manifold that connects the upper channel and the lower channel, and the partition plate extends to the manifold and stops in front of the manifold; the manifold is used to allow the gas-liquid phase mixture in the upper channel to merge with the liquid fluid in the lower channel.

6. The heat exchanger according to claim 1, characterized in that, The height of the upper channel is greater than the height of the lower channel.

7. The heat exchanger according to any one of claims 1 to 6, characterized in that, Both the upper and lower channels are equipped with multiple vertical partitions, which divide the upper and lower channels into multiple guide channels corresponding to the upper and lower positions. The width of the multiple guide channels gradually decreases from the windward side to the leeward side of the flat tube.

8. The heat exchanger according to claim 7, characterized in that, The inner wall of the flow channel is provided with ribs extending along the length of the flow channel, and the ribs are arranged at intervals on the inner wall of the flow channel.

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