Multilayer sleeve structure and microchannel heat exchanger

Abstract

This invention belongs to the field of refrigeration technology and equipment, specifically relating to a multi-layered sleeve liquid distribution structure and a microchannel heat exchanger. The multi-layered sleeve liquid distribution structure includes a first sleeve, a second sleeve, a third sleeve, a fourth sleeve, a fifth sleeve, an inlet pipe, a connecting clamp, a manifold, a cap, a partition, and flat tubes. The inlet hole of the first sleeve is connected to the inlet pipe, and the outlet hole of the first sleeve is connected to the manifold via the connecting clamp. The manifold is divided into several independent chambers by partitions, each chamber containing one or more flat tubes. The multi-layered sleeve liquid distribution structure proposed in this invention uses nested multi-layered sleeves to form a liquid distribution flow path. The binary structure and flow path arrangement ensure that the local resistance, friction resistance, and gravity effect are all the same for each branch, thereby achieving better liquid distribution uniformity.

Description

Technical Field

[0001] This invention belongs to the field of refrigeration technology and equipment, specifically relating to a multi-layer sleeve liquid distribution structure and a microchannel heat exchanger. Background Technology

[0002] Microchannel heat exchangers are high-efficiency, compact heat exchangers, mainly composed of flat tubes with multiple microchannels and manifolds for flow distribution and convergence. At the evaporator inlet, the refrigerant is typically in a gas-liquid two-phase state. When the liquid distribution in the microchannel heat exchanger is uneven, branches with less liquid will experience dry evaporation and superheating, while branches with more liquid will experience liquid carryover at the outlet, thus hindering the heat exchanger's capacity. To improve the performance of microchannel heat exchangers, a reasonable liquid distribution system is essential. The design of the liquid distribution structure needs to consider multiple factors, including complexity, manufacturing difficulty, and production cost.

[0003] There are many existing improvements to the liquid separation structure of microchannel heat exchangers, and the characteristics and advantages and disadvantages of different structures vary. They generally have the following drawbacks:

[0004] 1. Traditional external distributors are mature in copper tube heat exchangers, but microchannel heat exchangers have a large number of flat tubes. Using external distributors results in a complex structure, higher cost, and is not conducive to compressing space and forming an integrated liquid distribution structure.

[0005] 2. Setting up a liquid distribution structure inside the manifold of a microchannel heat exchanger facilitates integrated flow distribution. However, the internal space of the manifold is small, and complex liquid distribution structures are difficult to apply due to process and cost issues.

[0006] 3. For the liquid distribution structure in the manifold, the uniformity of liquid distribution in each branch is mainly affected by local resistance, friction resistance, and gravity. Theoretically, when the three effects in each branch are equal, completely uniform liquid distribution can be achieved. However, the existing structure makes it difficult to control the three effects to be exactly the same. Summary of the Invention

[0007] This invention proposes a multi-layered sleeve liquid distribution structure and a microchannel heat exchanger. It mainly uses multiple layers of sleeves nested together to form a liquid distribution flow path. By utilizing the two-part structure and the arrangement of the flow path, the local resistance, friction resistance, and gravity effect of each branch are the same, thereby achieving better liquid distribution uniformity.

[0008] The technical solution of this invention to solve the above problems is: a multi-layer sleeve liquid distribution structure, which is special in that:

[0009] Includes the first sleeve, second sleeve, third sleeve, fourth sleeve, fifth sleeve, inlet pipe, connecting clamp, manifold, plug cap, partition, and flat pipe;

[0010] The first sleeve, the second sleeve, the third sleeve, the fourth sleeve, and the fifth sleeve are coaxially nested from the outside to the inside.

[0011] The first sleeve has a first sleeve inlet hole and a first sleeve outlet hole on its wall surface, and the second sleeve has a second sleeve inlet hole, a second sleeve two-part hole, a second sleeve first channel, a second sleeve two-part port, a second sleeve second channel, and a second sleeve channel port on its wall surface.

[0012] The wall of the third sleeve has an inlet hole and an outlet hole.

[0013] The wall of the fourth sleeve has a four-point hole, a first channel, a two-point opening, a second channel, and a channel port.

[0014] The channel of the second sleeve, together with the inner wall of the first sleeve and the outer wall of the third sleeve, forms a diversion channel; the channel of the fourth sleeve, together with the inner wall of the third sleeve and the outer wall of the fifth sleeve, forms a diversion channel.

[0015] The first inlet hole of the first sleeve, the second inlet hole of the second sleeve, the third inlet hole of the third sleeve, and the fourth two-point hole of the fourth sleeve are connected in sequence.

[0016] The fourth sleeve's first channel includes a horizontal channel, with the second-part opening of the fourth sleeve located at the center of this horizontal channel, thus ensuring equal gravitational force during flow splitting. The first channel of the fourth sleeve is symmetrical about the center of this second-part opening. Each end of the first channel is connected to an inlet of a connecting channel. The second channel of the fourth sleeve also includes a horizontal channel, with the connecting channel connecting to the second-part opening of the fourth sleeve located at the center of the horizontal channel, thus ensuring equal gravitational force during flow splitting. The second channel of the fourth sleeve is symmetrical about the center of the second channel of the fourth sleeve. The connecting channel is perpendicular to the second channel of the fourth sleeve at the connection point, thus ensuring that the local resistance is the same each time the flow is split. The two ends of the second channel of the fourth sleeve are the ports of the fourth sleeve channel, and each port of the fourth sleeve channel is connected to a third sleeve outlet hole. The two connecting channels and the two second channels of the fourth sleeve are symmetrical about the center of the second channel of the fourth sleeve. Along the channel direction, the friction length from the second channel of the fourth sleeve to any port of the fourth sleeve channel is equal, thus ensuring that the length of each flow path is the same and the friction resistance is the same.

[0017] The outlet hole of each third sleeve corresponds to and is connected to the two-part hole of the second sleeve of a second sleeve.

[0018] The second sleeve's first channel includes a horizontal channel, with the second sleeve's two-part opening located at the center of this horizontal channel, thus ensuring equal gravitational force during flow splitting. The second sleeve's first channel is symmetrical about the center of this two-part opening. Each end of the second sleeve's first channel is connected to an inlet of a connecting channel. The second sleeve's second channel also includes a horizontal channel, with the connecting channel connecting to the second sleeve's two-part opening located at the center of the horizontal channel within the second sleeve's second channel, thus ensuring equal gravitational force during flow splitting. The second sleeve and second channel are symmetrical about the center of the second sleeve's two-part opening. The connecting channel and the second sleeve's second channel are perpendicular to each other at the connection point, thus ensuring that the local resistance is the same each time the flow is split. The two ends of the second sleeve's second channel are the second sleeve channel ports, and each second sleeve channel port is connected to a first sleeve outlet hole. The two connecting channels and the two second sleeve's second channels corresponding to each second sleeve's two-part opening are symmetrical about the center of the second sleeve's two-part opening. Along the channel direction, the friction length from the second sleeve's two-part opening to any second sleeve channel port is equal, thus ensuring that the length of each flow path is the same and the friction resistance is the same.

[0019] The inlet hole of the first sleeve is connected to the inlet pipe, and the outlet hole of the first sleeve is connected to the manifold through a connecting clamp. The manifold is equipped with partitions at intervals, which divide the manifold into several independent chambers, each corresponding to a connecting clamp. One or more flat tubes are inserted in each chamber.

[0020] Furthermore, the upper and lower ends of the aforementioned manifold are fitted with caps for sealing.

[0021] Furthermore, the first, second, third, fourth, and fifth sleeves are coaxially nested from the outside to the inside and then brazed.

[0022] In some embodiments, the inner diameter of the first sleeve is equal to or slightly larger than the outer diameter of the second sleeve, the inner diameter of the second sleeve is equal to or slightly larger than the outer diameter of the third sleeve, the inner diameter of the third sleeve is equal to or slightly larger than the outer diameter of the fourth sleeve, and the inner diameter of the fourth sleeve is equal to or slightly larger than the outer diameter of the fifth sleeve, so as to facilitate nested assembly.

[0023] In some embodiments, the first sleeve outlet holes of the first sleeve are evenly distributed in the axial direction, and the inlet holes and the first sleeve outlet holes are 180° apart in the circumferential direction.

[0024] In some embodiments, the cross-sectional area of ​​the inlet orifice of the second sleeve is equal to the cross-sectional area of ​​the inlet orifice, and the flow cross-sectional area of ​​the first channel of the second sleeve is greater than or equal to the flow cross-sectional area of ​​the second channel of the second sleeve. The cross-sectional area of ​​the inlet orifice of the second sleeve is greater than or equal to the flow cross-sectional area of ​​the first channel, the flow cross-sectional area of ​​the first channel is greater than or equal to the flow cross-sectional area of ​​the second channel of the third sleeve, and the flow cross-sectional area of ​​the second channel of the third sleeve is greater than or equal to the cross-sectional area of ​​the outlet orifice. This ensures that the flow rate after diversion matches the flow area.

[0025] In some embodiments, the outlet holes of the third sleeve are evenly distributed axially, and the inlet holes of the third sleeve are located axially at the center of two of the outlet holes. The inlet holes and outlet holes of the third sleeve are coaxially aligned. The diameter of the inlet hole of the third sleeve is greater than or equal to the diameter of the outlet hole of the third sleeve.

[0026] In some embodiments, the flow cross-sectional area of ​​the first channel of the fourth sleeve is less than or equal to the flow cross-sectional area of ​​the inlet orifice of the third sleeve. The flow cross-sectional area of ​​the first channel of the fourth sleeve is greater than or equal to the flow cross-sectional area of ​​the second channel of the fourth sleeve. This ensures that the flow rate after diversion matches the flow area.

[0027] In addition, the present invention also proposes a microchannel heat exchanger, which includes the above-mentioned multi-layer sleeve liquid distribution structure.

[0028] Advantages of this invention:

[0029] 1. This invention utilizes a two-part structure and the arrangement of the liquid distribution flow path to ensure that the local resistance, friction resistance, and gravity effects of each branch are the same, thereby achieving better liquid distribution uniformity.

[0030] 2. The present invention adopts a multi-layer sleeve form, and arranges the liquid distribution flow path on the circumference of the sleeve, which effectively expands the arrangement space of the flow path; through the tortuous arrangement of the flow path on the circumference and the cooperation between the inner and outer sleeves to perform multiple divisions, integrated liquid distribution is realized in a limited space.

[0031] 3. The multi-layered sleeve of the present invention arranges flow paths on the circumference, leaving the space in the center of the sleeve empty. This not only saves material costs, but also allows for the installation of other pipelines of the microchannel heat exchanger in the hollow part for use in conjunction with it, making it easier to achieve a compact structure of the heat exchanger.

[0032] 4. The present invention creates grooves on the sleeve and constructs flow paths through the nesting of tubes, which is structurally beneficial for processing and assembly. Attached Figure Description

[0033] Figure 1 This is a diagram of a multi-layered tubing liquid separation structure;

[0034] Figure 2This is a diagram of a multi-layer sleeve structure;

[0035] Figure 3 This is the structural diagram of the first set of pipes;

[0036] Figure 4 This is the structural diagram and flow path diagram of the second casing;

[0037] Figure 5 This is a structural diagram of the third casing;

[0038] Figure 6 This is the structural diagram and flow path diagram of the fourth set of pipes;

[0039] Figure 7 This is a structural diagram of an 8-channel liquid separator multilayer sleeve;

[0040] Figure 8 This is a structural diagram of a 4-channel liquid separation multilayer sleeve.

[0041] The figure shows: First sleeve 1, Second sleeve 2, Third sleeve 3, Fourth sleeve 4, Fifth sleeve 5, Inlet pipe 6, Connecting clamp 7, Manifold 8, Plug cap 9, Partition 10, Flat pipe 11;

[0042] First sleeve inlet hole 101, first sleeve outlet hole 102, second sleeve inlet hole 201, second sleeve two-way hole 202, second sleeve first channel 203, second sleeve two-way port 204, second sleeve second channel 205, second sleeve channel port 206;

[0043] Third sleeve inlet hole 301, third sleeve outlet hole 302;

[0044] The fourth sleeve has a two-part hole 401, a first channel of the fourth sleeve 402, a two-part port of the fourth sleeve 403, a second channel of the fourth sleeve 404, and a channel port of the fourth sleeve 405. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention.

[0046] Example 1

[0047] A multi-layer sleeve liquid distribution structure, which is a preferred structure provided by the present invention, is used to divide the inlet flow into 16 channels.

[0048] Specifically, see Figures 1-6 The multi-layered sleeve liquid distribution structure includes a first sleeve 1, a second sleeve 2, a third sleeve 3, a fourth sleeve 4, a fifth sleeve 5, an inlet pipe 6, a connecting clamp 7, a manifold 8, a plug cap 9, a partition 10, and a flat tube 11. The first sleeve 1, the second sleeve 2, the third sleeve 3, the fourth sleeve 4, and the fifth sleeve 5 are coaxially nested from the outside to the inside.

[0049] The first sleeve 1 has one first sleeve inlet hole 101 and sixteen first sleeve outlet holes 102 on its wall surface. The second sleeve 2 has a second sleeve inlet hole 201, a second sleeve split hole 202, a second sleeve first channel 203, a second sleeve split port 204, a second sleeve second channel 205, and a second sleeve channel port 206 on its wall surface. The third sleeve 3 has an inlet hole 301 and a third sleeve outlet hole 302 on its wall surface. The fourth sleeve 4 has a fourth sleeve split hole 401, a fourth sleeve first channel 402, a fourth sleeve split port 403, a fourth sleeve second channel 404, and a fourth sleeve channel port 405 on its wall surface. The channels of the second sleeve 2 cooperate with the inner wall of the first sleeve 1 and the outer wall of the third sleeve 3 to form a diversion channel. The channels of the fourth sleeve 4 cooperate with the inner wall of the third sleeve 3 and the outer wall of the fifth sleeve 5 to form a diversion channel.

[0050] The inlet hole 101 of the first sleeve 1, the second inlet hole 201 of the second sleeve 2, the third inlet hole 301 of the third sleeve 3, and the fourth inlet hole 401 of the fourth sleeve 4 are connected in sequence.

[0051] See Figure 1 The first sleeve 1 has an inlet hole 101 connected to the inlet pipe 6, and outlet holes 102 of the first sleeve are arranged at equal intervals. Each outlet hole 102 of the first sleeve is connected to the manifold 8 through a connecting clamp 7. The manifold 8 has partitions 10 at intervals inside, dividing it into several independent chambers, each corresponding to a connecting clamp 7. Each chamber contains one or more flat tubes 11. The flat tubes 11 have several microchannels inside. The upper and lower ends of the manifold 8 are sealed with caps 9.

[0052] Referring to 6, the first channel 402 of the fourth sleeve 4 includes a horizontal channel, and the second opening 401 of the fourth sleeve is located at the center of the horizontal channel, thereby ensuring that the gravitational force is the same during flow splitting. The first channel 402 of the fourth sleeve is symmetrical about the second opening 401. The two ends of the first channel 402 of the fourth sleeve are respectively connected to the inlet of a connecting channel. The second channel 404 of the fourth sleeve also includes a horizontal channel, and the connecting channel is connected to the second opening 403 of the fourth sleeve at the center of the horizontal channel in the second channel 404, thereby ensuring that the gravitational force is the same during flow splitting. The second channel 404 of the fourth sleeve is symmetrical about the center of the second port 403 of the fourth sleeve. The connecting channel and the second channel 404 of the fourth sleeve are perpendicular to each other at the connection point, thus ensuring that the local resistance is the same each time the flow is split. The two ends of the second channel 404 of the fourth sleeve are the channel ports 405 of the fourth sleeve. Each channel port 405 is connected to a third sleeve outlet hole 302. The two connecting channels and the two second channels 404 of the fourth sleeve are symmetrical about the center of the second port 401 of the fourth sleeve. Along the channel direction, the friction length from the second port 401 of the fourth sleeve to any channel port 405 of the fourth sleeve is equal, thus ensuring that the length of each flow path is the same and the friction resistance is the same.

[0053] The two-way flow path arrangement of the fourth sleeve 4 can ensure that the friction resistance, local resistance and gravity effect of each flow path are exactly the same.

[0054] In some embodiments, the flow cross-sectional area of ​​the first channel 402 of the fourth sleeve is less than or equal to the flow cross-sectional area of ​​the inlet hole 301 of the third sleeve. The flow cross-sectional area of ​​the first channel 402 of the fourth sleeve is greater than or equal to the flow cross-sectional area of ​​the second channel 404 of the fourth sleeve. This ensures that the flow rate after diversion matches the flow area.

[0055] In some embodiments, the flow cross-sectional area of ​​the first channel 402 of the fourth sleeve is less than or equal to the flow cross-sectional area of ​​the inlet hole 301 of the third sleeve. The flow cross-sectional area of ​​the first channel 402 of the fourth sleeve is greater than or equal to the flow cross-sectional area of ​​the second channel 404 of the fourth sleeve. This ensures that the flow rate after diversion matches the flow area.

[0056] The third sleeve outlet hole 302 of each third sleeve 3 corresponds to and is connected to the second sleeve bi-hole 202 of a second sleeve 2.

[0057] See Figure 4The second sleeve 2's second sleeve first channel 203 includes a horizontal channel, with the second sleeve bi-splitting hole 202 located at the center of the horizontal channel, thus ensuring the same gravitational force during flow splitting. The second sleeve first channel 203 is symmetrical about the second sleeve bi-splitting hole 202. The two ends of the second sleeve first channel 203 are respectively connected to the inlet of a connecting channel. The second sleeve second channel 205 also includes a horizontal channel, with the connecting channel connected to the second sleeve bi-splitting hole 204 at the center of the horizontal channel in the second sleeve second channel 205, thus ensuring the same gravitational force during flow splitting. The second sleeve and second channel 205 are symmetrical about the center of the second sleeve bi-port 204. The connecting channel and the second sleeve and second channel 205 are perpendicular to each other at the connection point, thus ensuring that the local resistance is the same each time the flow is split. The two ends of the second sleeve and second channel 205 are second sleeve channel ports 206, and each second sleeve channel port 206 is connected to a first sleeve outlet hole 102. The two connecting channels and the two second sleeve and second channel 205 corresponding to each second sleeve bi-port 202 are symmetrical about the center of the second sleeve bi-port 202. Along the channel direction, the friction length from the second sleeve bi-port 202 to any second sleeve channel port 206 is equal, thus ensuring that the length of each flow path is the same and the friction resistance is the same.

[0058] The two-way flow path arrangement of the second sleeve 2 can ensure that the friction resistance, local resistance, and gravity effect of each flow path are exactly the same.

[0059] In some embodiments, the cross-sectional area of ​​the second sleeve inlet hole 201 is equal to the cross-sectional area of ​​the inlet hole 101, and the flow cross-sectional area of ​​the second sleeve first channel 203 is greater than or equal to the flow cross-sectional area of ​​the second sleeve second channel 205. This ensures that the flow rate after diversion matches the flow area.

[0060] In some embodiments, the first sleeve 1, the second sleeve 2, the third sleeve 3, the fourth sleeve 4, and the fifth sleeve 5 are coaxially nested from the outside to the inside and then brazed, so that the grooves opened on the second sleeve 2 and the fourth sleeve 4 form a closed flow path.

[0061] Generally, the thickness of the second sleeve 2 and the fourth sleeve 4 is 1mm to 8mm. In some embodiments, the inner diameter of the first sleeve 1 is equal to or slightly larger than the outer diameter of the second sleeve 2, the inner diameter of the second sleeve 2 is equal to or slightly larger than the outer diameter of the third sleeve 3, the inner diameter of the third sleeve 3 is equal to or slightly larger than the outer diameter of the fourth sleeve 4, and the inner diameter of the fourth sleeve 4 is equal to or slightly larger than the outer diameter of the fifth sleeve 5, which facilitates nested assembly.

[0062] In some embodiments, see Figure 3The first sleeve outlet holes 102 of the first sleeve 1 are evenly distributed in the axial direction, and the inlet holes 101 and the first sleeve outlet holes 102 are 180° apart in the circumferential direction. The diameter of the inlet hole 101 is greater than or equal to the diameter of the first sleeve outlet hole 102.

[0063] In some embodiments, see Figure 5 The third sleeve outlet holes 302 of the third sleeve 3 are evenly distributed in the axial direction, and the third sleeve inlet holes 301 are located at the center of two of the third sleeve outlet holes 302 in the axial direction. The third sleeve inlet holes 301 and the third sleeve outlet holes 302 are located on the same axis in the circumferential direction. The diameter of the third sleeve inlet hole 301 is greater than or equal to the diameter of the third sleeve outlet hole 302.

[0064] Example 2

[0065] Another multi-layer sleeve liquid distribution structure can be designed using the ideas provided by this invention, which divides the flow rate into 8 channels. Figure 7 This is a structural diagram of an 8-channel multilayer liquid separator. The first separator (1) has one inlet hole and eight outlet holes. The second separator (2) has one inlet hole, two bi-channel holes, two first channels, four second channels, and eight channel ports. The third separator (3) has one inlet hole and two outlet holes. The fourth separator (4) has one bi-channel hole, one first channel, and two channel ports.

[0066] Example 3

[0067] Another multi-layer sleeve liquid distribution structure can be designed using the ideas provided by this invention. Figure 8 This is a structural diagram of a four-channel multilayer splitter tube. The first tube 1 has one inlet hole and four outlet holes. The second tube 2 has one inlet hole, two bi-channel holes, two first channels, and four channel ports. The third tube 3 has one inlet hole and two outlet holes. The fourth tube 4 has one bi-channel hole, one first channel, and two channel ports. This structure divides the flow rate evenly into four channels.

[0068] Similarly, the approach provided by this invention can be used to design a system that evenly divides the flow into 2... n The structure includes (4, 8, 16, 32...) lanes. The structure for lanes of 32 and above is more complex and will not be listed here.

[0069] The present invention also proposes a microchannel heat exchanger, which includes the above-mentioned multi-layer sleeve liquid distribution structure. Thus, the microchannel heat exchanger also contains all the functions and effects of the above-mentioned multi-layer sleeve liquid distribution structure, which will not be repeated here.

[0070] The above description is merely an embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification and drawings, or direct or indirect applications in other related system fields, are similarly included within the scope of protection of the present invention.

Claims

1. A multi-layer sleeve liquid distribution structure, characterized in that: Includes the first sleeve (1), the second sleeve (2), the third sleeve (3), the fourth sleeve (4), the fifth sleeve (5), the inlet pipe (6), the connecting clamp (7), the manifold (8), the plug cap (9), the partition (10), and the flat pipe (11); The first sleeve (1), the second sleeve (2), the third sleeve (3), the fourth sleeve (4), and the fifth sleeve (5) are coaxially nested from the outside to the inside; The first sleeve (1) has a first sleeve inlet hole (101) and a first sleeve outlet hole (102) on its wall surface; the second sleeve (2) has a second sleeve inlet hole (201), a second sleeve split hole (202), a second sleeve first channel (203), a second sleeve split port (204), a second sleeve second channel (205), and a second sleeve channel port (206) on its wall surface; the third sleeve (3) has a third sleeve inlet hole (301) and a third sleeve outlet hole (302) on its wall surface. 02); The wall of the fourth sleeve (4) has a fourth sleeve two-part hole (401), a fourth sleeve first channel (402), a fourth sleeve two-part opening (403), a fourth sleeve second channel (404), and a fourth sleeve channel port (405); The channel of the second sleeve (2) cooperates with the inner wall of the first sleeve (1) and the outer wall of the third sleeve (3) to form a diversion channel, and the channel of the fourth sleeve (4) cooperates with the inner wall of the third sleeve (3) and the outer wall of the fifth sleeve (5) to form a diversion channel. The first sleeve inlet hole (101) of the first sleeve (1), the second sleeve inlet hole (201) of the second sleeve (2), the third sleeve inlet hole (301) of the third sleeve (3) and the fourth sleeve bi-section hole (401) of the fourth sleeve (4) are connected in sequence. The fourth sleeve (4) has a first channel (402) including a horizontal channel. The second hole (401) of the fourth sleeve is located at the center of the horizontal channel. The first channel (402) of the fourth sleeve is symmetrical about the second hole (401). The two ends of the first channel (402) of the fourth sleeve are respectively connected to the entrance of a connecting channel. The second channel (404) of the fourth sleeve also includes a horizontal channel. The connecting channel is connected to the second hole (403) of the fourth sleeve at the center of the horizontal channel in the second channel (404). The second channel (404) of the fourth sleeve is symmetrical about the second hole (401). The four sleeves are symmetrical about the center of the two-part port (403), and the connecting channel is perpendicular to the second channel of the fourth sleeve (404) at the connection point; the two ends of the second channel of the fourth sleeve (404) are the fourth sleeve channel ports (405), and each fourth sleeve channel port (405) is connected to a third sleeve outlet hole (302); the two connecting channels and the two second channels of the fourth sleeve (404) are symmetrical about the center of the four sleeve two-part port (401), and the length of the passage from the four sleeve two-part port (401) to any fourth sleeve channel port (405) along the channel direction is equal; The third sleeve outlet hole (302) of each third sleeve (3) corresponds to and is connected to the second sleeve two-part hole (202) of a second sleeve (2). The second sleeve first channel (203) of the second sleeve (2) includes a horizontal channel. The second sleeve two-part hole (202) is located at the center of the horizontal channel. The second sleeve first channel (203) is symmetrical about the second sleeve two-part hole (202). The two ends of the second sleeve first channel (203) are respectively connected to the entrance of a connecting channel. The second sleeve second channel (205) also includes a horizontal channel. The connecting channel is connected to the second sleeve two-part port (204) at the center of the horizontal channel in the second sleeve second channel (205). The second sleeve second channel (205) is symmetrical about the center of the second sleeve two-part port (204), and the connecting channel is perpendicular to the second sleeve second channel (205) at the connection point; the two ends of the second sleeve second channel (205) are the second sleeve channel ports (206), and each second sleeve channel port (206) is connected to a first sleeve outlet hole (102); the two connecting channels and the two second sleeve second channels (205) corresponding to each second sleeve two-part hole (202) are symmetrical about the center of the second sleeve two-part hole (202), and along the channel direction, the length of the path from the second sleeve two-part hole (202) to any second sleeve channel port (206) is equal; The first sleeve (1) has its first sleeve inlet hole (101) connected to the inlet pipe (6), and its first sleeve outlet hole (102) connected to the manifold (8) via a connecting clamp (7). The manifold (8) has partitions (10) spaced at intervals inside, which divide the manifold into several independent chambers, each corresponding to a connecting clamp (7). Each chamber contains one or more flat tubes (11).

2. The multi-layer sleeve liquid distribution structure according to claim 1, characterized in that: The upper and lower ends of the manifold (8) are fitted with caps (9) for sealing.

3. The multi-layer sleeve liquid distribution structure according to claim 2, characterized in that: The first sleeve (1), the second sleeve (2), the third sleeve (3), the fourth sleeve (4), and the fifth sleeve (5) are coaxially nested from the outside to the inside and then brazed.

4. A multi-layer sleeve liquid distribution structure according to any one of claims 1-3, characterized in that: The inner diameter of the first sleeve (1) is equal to or slightly larger than the outer diameter of the second sleeve (2), the inner diameter of the second sleeve (2) is equal to or slightly larger than the outer diameter of the third sleeve (3), the inner diameter of the third sleeve (3) is equal to or slightly larger than the outer diameter of the fourth sleeve (4), and the inner diameter of the fourth sleeve (4) is equal to or slightly larger than the outer diameter of the fifth sleeve (5).

5. The multi-layer sleeve liquid distribution structure according to claim 4, characterized in that: The first sleeve outlet hole (102) of the first sleeve (1) is evenly distributed in the axial direction, and the inlet hole (101) and the first sleeve outlet hole (102) are 180° apart in the circumferential direction.

6. The multi-layer sleeve liquid distribution structure according to claim 5, characterized in that: The cross-sectional area of ​​the inlet hole (201) of the second sleeve is equal to the cross-sectional area of ​​the inlet hole (101), and the flow cross-sectional area of ​​the first channel (203) of the second sleeve is greater than or equal to the flow cross-sectional area of ​​the second channel (205) of the second sleeve.

7. The multi-layer sleeve liquid distribution structure according to claim 6, characterized in that: The third sleeve outlet holes (302) of the third sleeve (3) are evenly distributed in the axial direction, and the third sleeve inlet hole (301) is located in the axial direction at the center of two of the third sleeve outlet holes (302). The third sleeve inlet hole (301) and the third sleeve outlet hole (302) are located on the same axis in the circumferential direction.

8. The multi-layer sleeve liquid distribution structure according to claim 7, characterized in that: The diameter of the inlet hole (301) of the third sleeve is greater than or equal to the diameter of the outlet hole (302) of the third sleeve.

9. A multi-layer sleeve liquid distribution structure according to claim 8, characterized in that: The flow cross-sectional area of ​​the first channel (402) of the fourth sleeve is less than or equal to the flow cross-sectional area of ​​the inlet hole (301) of the third sleeve; the flow cross-sectional area of ​​the first channel (402) of the fourth sleeve is greater than or equal to the flow cross-sectional area of ​​the second channel (404) of the fourth sleeve.

10. A microchannel heat exchanger, characterized in that: Includes the multi-layer sleeve liquid distribution structure as described in any one of claims 1-9.

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