A high-efficiency composite multi-row microchannel heat exchanger

Abstract

This invention discloses a high-efficiency composite multi-row microchannel heat exchanger. At least two rows of microchannel flat tubes are arranged between the upper and lower collectors. Each row of microchannel flat tubes includes several groups of microchannel flat tubes. The upper end of each group of microchannel flat tubes is connected to the upper collector, and the lower end is connected to the lower collector. In adjacent rows of microchannel flat tubes, the number of groups of microchannel flat tubes is the same, and the groups of microchannel flat tubes in adjacent rows are arranged opposite each other. Each group of microchannel flat tubes contains multiple parallel microchannel flat tubes with smooth sidewall surfaces. In adjacent rows of microchannel flat tubes, the microchannel flat tubes in the opposite groups are staggered, with the gap between two adjacent microchannel flat tubes in one group corresponding to the gap between two adjacent microchannel flat tubes in another group. This invention uses at least two rows of microchannel flat tubes, and through a reasonable structural design, can further improve the heat exchange efficiency of the microchannel heat exchanger.

Description

Technical Field

[0001] This invention belongs to the field of heat exchange equipment and enhanced heat transfer technology, specifically relating to a high-efficiency composite multi-row microchannel heat exchanger. Background Technology

[0002] Existing microchannel heat exchangers typically have fins attached to adjacent microchannel flat tubes in a folded manner. This structural feature makes drainage difficult, and poor drainage can easily lead to operational problems such as frost or dust accumulation, resulting in a decrease in the heat exchange efficiency of the microchannel heat exchanger as it operates.

[0003] To address this technical problem, those skilled in the art have proposed a solution: by adjusting the spacing of the microchannel flat tubes, the drainage performance of the microchannel flat tubes is increased without the need for fins, thereby preventing water droplets from adhering to the outer surface of the microchannel flat tubes. This avoids operational obstacles such as frost or dust accumulation caused by poor drainage, which would reduce the heat exchange efficiency of the microchannel heat exchanger. However, this type of microchannel heat exchanger still has the following problems: because it uses a single-row configuration, the air flow area within the microchannel heat exchanger is limited, resulting in limited improvement in heat exchange efficiency. Furthermore, once heat exchange stabilizes, a relatively stable temperature gradient layer forms on the surface of the microchannel flat tubes as the air flows through the heat exchanger, preventing the full utilization of the air's heat exchange potential and further affecting the improvement of the microchannel heat exchanger's heat exchange efficiency. Summary of the Invention

[0004] To address the problems existing in the prior art, the present invention aims to provide a high-efficiency composite multi-row microchannel heat exchanger. The present invention employs multiple rows (at least two rows) of microchannel flat tubes, and through reasonable structural design, it can further improve the heat exchange efficiency of the microchannel heat exchanger.

[0005] The technical solution adopted in this invention is as follows:

[0006] A high-efficiency composite multi-row microchannel heat exchanger includes an upper collector and a lower collector arranged parallel below the upper collector. At least two rows of microchannel flat tubes are arranged between the upper collector and the lower collector. Each row of microchannel flat tubes includes several groups of microchannel flat tubes. The upper end of each group of microchannel flat tubes is connected to the upper collector and the lower end is connected to the lower collector.

[0007] In two adjacent rows of microchannel flat tubes, the number of microchannel flat tube groups is the same. The microchannel flat tube groups in two adjacent rows of microchannel flat tubes are arranged opposite each other. Each group of microchannel flat tubes contains multiple parallel microchannel flat tubes with smooth sidewall surfaces.

[0008] In two adjacent rows of microchannel flat tubes, the microchannel flat tubes in the oppositely arranged microchannel flat tube groups are staggered, with the microchannel flat tubes in one microchannel flat tube group facing the gap between two adjacent microchannel flat tubes in another microchannel flat tube group.

[0009] Preferably, when there are three or more rows of microchannel flat tubes, the microchannel flat tubes in the two rows of microchannel flat tubes are arranged opposite each other.

[0010] Preferably, when there are three or more rows of microchannel flat tubes, all rows of microchannel flat tubes are sequentially denoted as the (n-1)th row of microchannel flat tubes, the nth row of microchannel flat tubes, the (n+1)th row of microchannel flat tubes, and so on. The distance between the (n-1)th row of microchannel flat tubes and the nth row of microchannel flat tubes is less than the distance between the nth row of microchannel flat tubes and the (n+1)th row of microchannel flat tubes, where n is a positive integer greater than or equal to 2.

[0011] Preferably, in two adjacent rows of microchannel flat tubes, the microchannel flat tube groups in one row are arranged at equal intervals of spacing A, and the microchannel flat tube groups in the other row are arranged alternately with spacings of spacing B and spacing C, wherein spacing A ≤ spacing B < spacing C.

[0012] Preferably, in each group of microchannel flat tubes, the spacing between adjacent microchannel flat tubes is 1.9-2 mm; the spacing between two adjacent groups of microchannel flat tubes is 4-6 mm; and the spacing between two adjacent rows of microchannel flat tubes is 9-15 mm.

[0013] Preferably, each microchannel flat tube has multiple parallel flow channels, the upper end of which is connected to the upper collector and the lower end of which is connected to the lower collector;

[0014] The flow channels at both ends of the microchannel flat tube in the width direction are D-shaped tubes, with one side of the curved surface of the D-shaped tube facing the outside of the end of the microchannel flat tube in the width direction. The remaining flow channels in the microchannel flat tube are rectangular tubes.

[0015] Preferably, the width of the flow channel cross-section is 0.20-0.35 mm, the length is 0.55-0.70 mm, and the spacing between adjacent flow channels is 0.79-0.94 mm; wherein, the width direction of the flow channel cross-section is the thickness direction of the microchannel flat tube, and the length direction of the flow channel cross-section is the width direction of the microchannel flat tube.

[0016] Preferably, both the upper and lower collectors are provided with a diversion baffle. The diversion baffle is located at the junction between two adjacent groups of microchannel flat tubes. The diversion baffle in the upper collector and the diversion baffle in the lower collector make the several groups of microchannel flat tubes sequentially connected to form a serpentine path.

[0017] The upper collector has a refrigerant inlet and a refrigerant outlet at both ends; or the upper collector has a refrigerant inlet and the lower collector has a refrigerant outlet; or the upper collector has a refrigerant outlet and the lower collector has a refrigerant inlet; or the lower collector has a refrigerant inlet and a refrigerant outlet at both ends; the refrigerant inlet and refrigerant outlet are respectively connected to the two ends of the serpentine passage.

[0018] Preferably, the microchannel flat tube is a straight flat tube with a width of 7-12mm and a thickness of 0.65-0.75mm; both ends of the microchannel flat tube are rounded along the width direction.

[0019] Preferably, each row of microchannel flat tubes is provided with four groups of microchannel flat tubes, and the ratio of the number of microchannel flat tubes in the four groups of microchannel flat tubes is (21-23): (25-27): (25-27): (21-23).

[0020] The present invention has the following beneficial effects:

[0021] In the high-efficiency composite multi-row microchannel heat exchanger of this invention, at least two rows of microchannel flat tubes are arranged. In adjacent rows of microchannel flat tubes, the microchannel flat tubes in the oppositely arranged microchannel flat tube groups are staggered. The microchannel flat tubes in one microchannel flat tube group are opposite to the gap between two adjacent microchannel flat tubes in another microchannel flat tube group. This design extends the airflow area and the contact distance with the microchannel flat tubes, increasing the heat exchange area. On the other hand, it causes the airflow channel (i.e., the gap between two adjacent microchannel flat tubes) to have a sudden contraction and expansion structure, inducing vortices, breaking the boundary layer in the airflow direction, blocking the development of the air side boundary layer, and providing turbulence. This intensifies the mixing and heat exchange of hot and cold air, expands the heat exchange area, improves heat exchange efficiency, and has a better effect on air heat exchange. Meanwhile, each group of microchannel flat tubes in this invention contains multiple parallel microchannel flat tubes with smooth sidewall surfaces. The outer surface of the microchannel flat tubes is smooth and finless. The vertical arrangement of the microchannel flat tubes helps reduce the adhesion of water droplets to the outer surface of the microchannel flat tubes. Under the combined action of wind and gravity, drainage performance is effectively improved, ensuring drainage and defrosting performance. Furthermore, the simple air channel structure reduces the pressure drop on the air side and the difficulty of processing and manufacturing. In summary, this invention uses multiple rows (at least two rows) of microchannel flat tubes, and through reasonable structural design, can further improve the heat exchange efficiency of the microchannel heat exchanger. Attached Figure Description

[0022] Figure 1 This is a front view of the high-efficiency composite multi-row (three-row) microchannel heat exchanger of Embodiment 1 of the present invention;

[0023] Figure 2 for Figure 1 The right view;

[0024] Figure 3 for Figure 1 Top view;

[0025] Figure 4 This is a cross-sectional view of the current collector in Embodiment 1 of the present invention;

[0026] Figure 5 This is a cross-sectional view of the current collector in Embodiment 1 of the present invention;

[0027] Figure 6 This is a schematic diagram of the refrigerant flow path in Embodiment 1 of the present invention;

[0028] Figure 7(a) is a right view of the upper collector in Embodiment 1 of the present invention;

[0029] Figure 7(b) is a top view of the current collector in Embodiment 1 of the present invention;

[0030] Figure 8(a) is a right view of the collector in Embodiment 1 of the present invention;

[0031] Figure 8(b) is a top view of the current collector in Embodiment 1 of the present invention;

[0032] Figure 9 This is a horizontal cross-sectional view of the microchannel flat tube in Embodiment 1 of the present invention;

[0033] Figure 10 This is an isometric view of the front support plate of Embodiment 1 of the present invention;

[0034] Figure 11 This is an isometric view of the rear support plate in Embodiment 1 of the present invention;

[0035] Figure 12 This is a top-view streamline distribution diagram of the high-efficiency composite multi-row microchannel heat exchanger in Embodiment 1 of the present invention;

[0036] Figure 13 This is a top-view temperature contour map showing the numerical simulation of the high-efficiency composite multi-row microchannel heat exchanger of Embodiment 1 of the present invention.

[0037] Figure 14 This is a performance comparison chart between the high-efficiency composite multi-row microchannel heat exchanger of Embodiment 1 of the present invention and existing heat exchangers;

[0038] Figure 15 This is a front view of the high-efficiency composite multi-row (two-row) microchannel heat exchanger of Embodiment 2 of the present invention;

[0039] Figure 16 for Figure 15 The right view;

[0040] Figure 17 for Figure 15 Top view;

[0041] Figure 18 This is a cross-sectional view of the current collector in Embodiment 2 of the present invention;

[0042] Figure 19 This is a cross-sectional view of the current collector in Embodiment 2 of the present invention;

[0043] Figure 20 This is a schematic diagram of the refrigerant flow path in Embodiment 2 of the present invention;

[0044] Figure 21(a) is a right view of the upper collector in Embodiment 2 of the present invention;

[0045] Figure 21(b) is a top view of the current collector in Embodiment 2 of the present invention;

[0046] Figure 22(a) is a right view of the collector in Embodiment 2 of the present invention;

[0047] Figure 22(b) is a top view of the current collector in Embodiment 2 of the present invention;

[0048] Figure 23 This is a horizontal cross-sectional view of the microchannel flat tube in Embodiment 2 of the present invention;

[0049] Figure 24 This is a top-view streamline distribution diagram of the high-efficiency composite multi-row microchannel heat exchanger in Embodiment 2 of the present invention;

[0050] Figure 25 This is a top-view temperature contour map showing the numerical simulation of the high-efficiency composite multi-row microchannel heat exchanger of Embodiment 2 of the present invention.

[0051] Figure 26 This is a performance comparison chart between the high-efficiency composite multi-row microchannel heat exchanger of Embodiment 2 of the present invention and existing heat exchangers;

[0052] Figure 27 This is a front view of the high-efficiency composite multi-row (two-row) microchannel heat exchanger of Embodiment 2 of the present invention;

[0053] Figure 28 for Figure 27 The right view;

[0054] Figure 29 for Figure 27 Top view;

[0055] Figure 30 This is a cross-sectional view of the current collector in Embodiment 3 of the present invention;

[0056] Figure 31 This is a cross-sectional view of the current collector in Embodiment 3 of the present invention;

[0057] Figure 32 This is a top-view streamline distribution diagram of the high-efficiency composite multi-row microchannel heat exchanger in Embodiment 3 of the present invention;

[0058] Figure 33 This is a top-view temperature contour map showing the numerical simulation of the high-efficiency composite multi-row microchannel heat exchanger in Embodiment 3 of the present invention.

[0059] Figure 34 This is a performance comparison chart of the high-efficiency composite multi-row microchannel heat exchanger of Embodiment 3 of the present invention and existing heat exchangers.

[0060] In the diagram: 1-Upper collector; 101-Pre-upper collector of upper collector; 102-Rearer collector of upper collector; 103-Outlet baffle of the front collector of upper collector; 104-Outlet baffle of the rear collector of upper collector; 105-Inlet baffle of the front collector of upper collector; 106-Inlet baffle of the rear collector of upper collector; 1012-Inlet baffle of upper collector; 1022-Outlet baffle of upper collector; 2-Inlet pipe section; 3-Outlet pipe section; 4-Outlet Side support plate; 5-Inlet side support plate; 501-Inlet side front support plate; 502-Inlet side rear support plate; 5013-Inlet side left support plate; 5023-Inlet side right support plate; 6-Microchannel flat tube; 6-1-Flow channel; 7-Lower collector; 701-Lower collector front collector; 702-Lower collector rear collector; 703-Lower collector front collector baffle; 704-Lower collector rear collector baffle; 7011-Lower collector baffle. Detailed Implementation

[0061] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0062] The present invention provides a high-efficiency composite multi-row microchannel heat exchanger, comprising an upper collector 1, a lower collector 7 arranged parallel below the upper collector 1, and at least two rows of microchannel flat tubes arranged between the upper collector 1 and the lower collector 7. Each row of microchannel flat tubes includes several groups of microchannel flat tubes, and the upper end of each group of microchannel flat tubes is connected to the upper collector 1 and the lower end is connected to the lower collector 7.

[0063] See Figure 4 , Figure 5 , Figure 18 , Figure 19 , Figure 30 and Figure 31 In two adjacent rows of microchannel flat tubes, the number of microchannel flat tube groups is the same. The microchannel flat tube groups in two adjacent rows of microchannel flat tubes are arranged opposite each other. Each microchannel flat tube group contains multiple parallel microchannel flat tubes with smooth sidewall surfaces.

[0064] Reference Figure 12 , Figure 13 Figure 24 , Figure 25 , Figure 32 and Figure 33In two adjacent rows of microchannel flat tubes, the microchannel flat tubes 6 in the microchannel flat tube groups are staggered. The microchannel flat tube 6 in one microchannel flat tube group is opposite to the gap between two adjacent microchannel flat tubes 6 in another microchannel flat tube group. Generally, the gap between the microchannel flat tube 6 in one microchannel flat tube group and the gap between two adjacent microchannel flat tubes 6 in another microchannel flat tube group should be aligned with the center of the gap.

[0065] Reference Figure 12 , Figure 13 Figure 24 , Figure 25 , Figure 32 and Figure 33 In the high-efficiency composite multi-row microchannel heat exchanger of the present invention, at least one row of microchannel flat tubes are arranged alternately back and forth. Figure 4 , Figure 5 , Figure 18 , Figure 19 , Figure 30 and Figure 31 The left and right directions in the middle, Figure 12 , Figure 13 Figure 24 , Figure 25 , Figure 32 and Figure 33 In the vertical direction, the staggered arrangement of microchannel flat tubes extends the airflow area and increases the heat exchange area. On the other hand, it blocks the development of the air side boundary layer and provides turbulence, intensifies the mixing of hot and cold air, and improves heat exchange efficiency.

[0066] The structural design of this invention allows for a further reduction in the orifice size of the microchannel flat tube compared to current mainstream microchannel flow channel sizes. Furthermore, the increased number of channels on the microchannel flat tube reduces refrigerant usage. Additionally, the parallel arrangement of the front and rear collectors improves channel blockage and enhances operational reliability. The heat transfer coefficient of the microchannel increases significantly with decreasing diameter. Compared to larger diameter channels, the boundary layer of the microchannel is thinner, resulting in more intense convective heat transfer, a more pronounced heat transfer effect, and better air heat exchange. Utilizing microchannel heat exchange effectively reduces the heat exchange area, decreases the overall size of the heat exchanger, ensures normal operation of the heat exchanger, and improves heat exchange efficiency.

[0067] The microchannel flat tubes arranged in parallel and crisscrossing patterns in this invention create a sudden contraction and expansion structure in the airflow channel, inducing vortices, breaking the boundary layer in the airflow direction, intensifying the exchange of hot and cold air and expanding the heat exchange area. The smaller the spacing between the flat tubes, the greater the wind speed, the greater the vortex intensity, the better the turbulence effect, the greater the heat transfer coefficient, and the more obvious the heat exchange effect, resulting in better heat exchange for the air.

[0068] The microchannel flat tube of this invention has a smooth outer surface and no fins. The vertical arrangement of the microchannel flat tube with its longitudinal axis perpendicular to the horizontal plane helps to reduce the adhesion of water droplets on the outside of the microchannel flat tube wall. Under the combined action of wind and gravity, it effectively improves drainage and ensures drainage and defrosting performance. Moreover, due to the simple structure of the air channel, the processing and manufacturing difficulty is reduced.

[0069] As an optional solution of the present invention, see [link to relevant documentation]. Figure 4 and Figure 5 When there are three or more rows of microchannel flat tubes, the microchannel flat tubes 6 in the microchannel flat tube group that are arranged opposite each other in two rows (such as the first row and the third row) are arranged facing each other.

[0070] As an optional embodiment of the present invention, when there are three or more rows of microchannel flat tubes, all rows of microchannel flat tubes are sequentially denoted as the (n-1)th row of microchannel flat tubes, the nth row of microchannel flat tubes, the (n+1)th row of microchannel flat tubes, and so on. The distance between the (n-1)th row of microchannel flat tubes and the nth row of microchannel flat tubes is less than the distance between the nth row of microchannel flat tubes and the (n+1)th row of microchannel flat tubes, where n is a positive integer greater than or equal to 2. See also... Figure 4 and Figure 5 Taking three rows as an example, the distance between the first row of microchannel flat tubes and the second row of microchannel flat tubes is smaller than the distance between the second row of microchannel flat tubes and the third row of microchannel flat tubes. From left to right, the distance between adjacent rows gradually increases. This ensures that the airflow resistance is relatively small and the heat exchange efficiency is guaranteed.

[0071] As an optional solution of the present invention, see [link to relevant documentation]. Figure 4 , Figure 5 , Figure 18 , Figure 19 , Figure 30 and Figure 31 In two adjacent rows of microchannel flat tubes, the microchannel flat tube groups in one row are arranged at equal intervals of spacing A, while the microchannel flat tube groups in the other row are arranged alternately at intervals of spacing B and spacing C, where spacing A ≤ spacing B < spacing C. This structure satisfies the requirement that "the microchannel flat tubes 6 in the relatively arranged microchannel flat tube groups are staggered, with the gap between adjacent microchannel flat tubes 6 in one microchannel flat tube group opposite to the gap between two adjacent microchannel flat tubes 6 in another microchannel flat tube group," and also reduces the overall width of the heat exchanger (see...). Figure 4 , Figure 5 , Figure 18 , Figure 19 , Figure 30 and Figure 31 The dimensions (left and right directions) make the entire heat exchanger more compact in structure while ensuring efficient heat exchange, which is conducive to miniaturization.

[0072] In a preferred embodiment of the present invention, the spacing between adjacent microchannel flat tubes 6 in each group of microchannel flat tubes is 1.9-2 mm. This small spacing arrangement of the microchannel flat tubes 6 increases the heat exchange area, intensifies heat exchange between the hot and cold working fluids, improves heat exchange efficiency, and compensates for the reduced heat dissipation capacity due to the lack of heat dissipation fins. Furthermore, it reduces the overall size of the heat exchanger model, improving its compactness. The spacing between two adjacent groups of microchannel flat tubes is 4-6 mm, which is also relatively small and serves a similar purpose to the smaller spacing between adjacent microchannel flat tubes 6, further reducing the overall size of the heat exchanger model. The spacing between two adjacent rows of microchannel flat tubes is 9-15 mm. This spacing facilitates relatively low overall flow resistance of the cooling air when it enters the gaps between the microchannel flat tubes from the left or right side of the heat exchanger, and can induce vortices, breaking the boundary layer in the airflow direction, intensifying the exchange of hot and cold air, and expanding the heat exchange area. For optional embodiments of the present invention, see [link to optional embodiments]. Figure 9 and Figure 23 Each microchannel flat tube 6 has multiple parallel flow channels. The upper end of each flow channel is connected to the upper collector 1, and the lower end is connected to the lower collector 7. The flow channels located at both ends of the microchannel flat tube 6 in the width direction are D-shaped tubes, with one side of the curved surface of the D-shaped tube facing outward from the end of the microchannel flat tube 6 in the width direction. Figure 9 and Figure 23 Taking the orientation shown as an example, the leftmost D-shaped tube curved surface faces the left end of the width direction of the microchannel flat tube 6, and the rightmost D-shaped tube curved surface faces the right end of the width direction of the microchannel flat tube 6. This structural design ensures the uniformity of heat dissipation at both ends of the microchannel flat tube 6. The remaining flow channels in the microchannel flat tube 6 are rectangular tubes.

[0073] As a preferred embodiment of the present invention, see Figure 9 and Figure 23 The width of the flow channel cross-section is 0.20-0.35 mm, the length is 0.55-0.70 mm, and the spacing between adjacent flow channels is 0.79-0.94 mm. The width direction of the flow channel cross-section is the thickness direction of the microchannel flat tube 6, and the length direction of the flow channel cross-section is the width direction of the microchannel flat tube 6. The width direction of the flow channel cross-section is the thickness direction of the microchannel flat tube 6 (i.e.,...). Figure 9 and Figure 23 The vertical direction shown is the same as the width direction of the microchannel flat tube 6. Figure 9 and Figure 23(As shown in the left and right directions). In this invention, the flow channel aperture size of the microchannel flat tube 6 is further reduced compared to the current mainstream microchannel flow channel size, and the number of channels on the microchannel flat tube 6 is large. On the one hand, this reduces the amount of refrigerant used; on the other hand, since the heat transfer coefficient of the microchannel increases significantly with the decrease in diameter, compared with existing larger diameter channels, the boundary layer of the microchannel is thinner, the convection heat transfer process is stronger, the heat transfer effect is more obvious, and the heat transfer effect on air is better. Utilizing microchannel heat exchange can effectively reduce the heat exchange area, reduce the overall size of the heat exchanger, ensure the normal operation of the heat exchanger, and improve the heat exchange efficiency. As a preferred embodiment of this invention, see [reference needed]. Figure 6 and Figure 20 Both the upper collector 1 and the lower collector 7 are equipped with flow-diverting baffles, which are located at the junction between two adjacent groups of microchannel flat tubes. The flow-diverting baffles in the upper collector 1 and the lower collector 7 connect the several groups of microchannel flat tubes sequentially to form a serpentine pathway. The upper collector 1 has a refrigerant inlet and a refrigerant outlet at both ends; or the upper collector 1 has a refrigerant inlet and the lower collector 7 has a refrigerant outlet; or the upper collector 1 has a refrigerant outlet and the lower collector 7 has a refrigerant inlet; or the lower collector 7 has a refrigerant inlet and a refrigerant outlet at both ends. The refrigerant inlet and refrigerant outlet are respectively connected to the two ends of the serpentine pathway.

[0074] As a preferred embodiment of the present invention, see Figure 9 and Figure 23 The microchannel flat tube 6 has rounded corners at both ends along its width direction, which helps to ensure uniform heat dissipation at both ends of the microchannel flat tube 6.

[0075] As a preferred embodiment of the above-mentioned solution of the present invention, the upper axis of the microchannel flat tube 6 along the height direction is perpendicular to the axis of the upper collector 1 and the axis of the lower collector 7. In this way, when the radiator of the present invention is used, the upper collector 1 and the lower collector 7 are in a horizontal state, and the microchannel flat tube 6 is in a vertical state, which is conducive to the smooth drainage of water on the surface of the microchannel flat tube 6 and effectively prevents dust accumulation.

[0076] As a preferred embodiment of the above-described solution of the present invention, see [reference needed]. Figure 1 , Figure 15 and Figure 27 The refrigerant inlet is connected to an inlet pipe section 2, and the refrigerant outlet is connected to an outlet pipe section 3. The inlet pipe section 2 and the outlet pipe section 3 facilitate the connection of the high-efficiency composite multi-row heat exchanger of the present invention with the external refrigerant delivery pipeline.

[0077] As a preferred embodiment of the above-described solution of the present invention, see [reference needed]. Figure 1 , Figure 2 , Figure 15 , Figure 16 , Figure 27 and Figure 28A support plate is connected between the upper collector 1 and the lower collector 7. One end of the support plate is fixedly connected to the upper collector 1 and the other end is fixedly connected to the lower collector 7. The support plate can fix the relative position between the upper collector 1 and the lower collector 7, and bear the load for the microchannel flat tube 6. This helps to prevent the microchannel flat tube 6 from deforming and being damaged under long-term stress.

[0078] Example 1

[0079] Please see Figure 1 , Figure 2 and Figure 3 In this embodiment, the high-efficiency composite multi-row microchannel heat exchanger is equipped with three rows of microchannel flat tubes, including an upper collector 1, a lower collector 7, several microchannel flat tubes 6, and other auxiliary accessories.

[0080] The upper collector 1 is located above the lower collector 7, and the upper collector 1 and the lower collector 7 are connected by several microchannel flat tubes 6. These microchannel flat tubes 6 are inserted into the upper and lower collector assemblies at a 90° angle to the horizontal plane. The vertical 90° arrangement of the microchannel flat tubes helps to reduce water droplet adhesion to the walls of the microchannel flat tubes 6 under gravity, thus improving frost and condensation under humid conditions. The upper collector 1 has heat exchanger inlets and outlets at its two vertical ends, with a refrigerant inlet pipe section 2 on the right end and a refrigerant outlet pipe section 3 on the left end. Both inlet pipe section 2 and outlet pipe section 3 are circular tubes with an inner diameter of 9.7 mm and a wall thickness of 0.8 mm. The upper collector 1 and the lower collector 7 are connected by several parallel microchannel flat tubes 6, with the longitudinal axis of the microchannel flat tubes 6 perpendicular to the horizontal plane. The microchannel flat tubes are arranged in three staggered rows. Within the same flow path, the spacing between the flat tubes is 2 mm, while in adjacent flow paths, the spacing alternates between 4 mm and 6 mm. The projection of any row of flat tubes in the vertical plane within the same flow path is located at the center of the distance between the two tubes in the adjacent row. The spacing between the first and second rows is 9 mm, and the spacing between the second and third rows is 15 mm. This staggered arrangement intensifies the exchange of hot and cold air and expands the heat exchange area. The smaller the spacing between the flat tubes, the better the turbulence effect, the larger the heat transfer coefficient, and the more significant the heat exchange effect, resulting in better air heat exchange. The microchannel flat tubes consist of 276 parallel flat tubes, with the flat tube ratio in each row of microchannel flat tubes being 21:25:25:21 in all four flow areas. The front collector (left collector) of the upper and lower collectors has two rows of staggered parallel microchannel flat tubes. The projection of the first row of microchannel flat tubes on the horizontal plane is parallel to the direction of the short side, and the center of the outermost microchannel flat tube is 10mm from the short side of both sides of the collector. The projection of the second row of microchannel flat tubes on the horizontal plane is parallel to the direction of the short side, and the center of the outermost microchannel flat tube is 11mm from the short side of both sides of the collector. The rear collector (right collector) of the upper and lower collectors has a single row of parallel microchannel flat tubes. The projection of the flat tubes on the horizontal plane is parallel to the direction of the short side, and the center of the outermost microchannel flat tube is 10mm from the short side of both sides of the collector.

[0081] like Figure 4 and Figure 5 As shown, both the upper collector 1 and the lower collector 7 are equipped with baffles for flow splitting. Both the upper collector 1 and the lower collector 7 are configured as left and right units. The left upper collector has two rows of microchannel flat tubes, and the right upper collector has one row of microchannel flat tubes. The left lower collector is the same as the left upper collector, with two rows of microchannel flat tubes, and the right lower collector is the same as the right upper collector, with one row of microchannel flat tubes. The upper collector has a total of four flow splitting baffles, and both the left and right upper collectors have two flow splitting baffles. (Refer to...) Figure 4The upper collector front collector outlet measuring baffle 103, upper collector rear collector outlet measuring baffle 104, upper collector front collector inlet measuring baffle 105, and upper collector rear collector inlet measuring baffle 106 are all located at 1 / 4 of the length of the upper collector, near the inlet side. The front collector outlet baffle 103 and the rear collector baffle (i.e., the upper collector rear collector outlet baffle 104) are both located at 3 / 4 of the length of the upper collector. Two flow-dividing baffles are arranged in the lower collector, one in each of the left and right lower collectors: the front lower collector baffle 703 and the rear lower collector baffle 704. Both the front lower collector baffle 703 and the rear lower collector baffle 704 are located at 1 / 2 of the length of the lower collector. By setting the baffles, the microchannel flat tube 6 is divided into four regions in the collector, forming multiple U-shaped refrigerant flow paths (i.e., the serpentine pathways) with vertical "U"-shaped flow, allowing the refrigerant to flow through multiple paths and achieve sufficient heat exchange. Specifically, the refrigerant flow direction is as follows: Figure 6 As shown.

[0082] As shown in Figures 7(a), 7(b), 8(a) and 8(b), both the upper collector 1 and the lower collector 7 are rectangular tubes; several microchannel flat tubes 6 are evenly and regularly inserted into the upper and lower collectors. Considering the difficulty of processing and versatility, the insertion depth accounts for 1 / 2 of the height of the cavity inside the collector.

[0083] like Figure 9 As shown, the microchannel flat tube 6 is a straight flat tube with a width (left-right direction) of 7mm and rounded corners on both sides, and a thickness (top-bottom direction) of 0.7mm. This is beneficial for improving the air-side heat transfer coefficient, mainly by increasing the air-side heat transfer area and blocking the development of the air-side boundary layer. Therefore, the microchannel flat tube 6 is arranged in three rows in a staggered pattern and inserted into the collector. At the same time, this creates a sudden contraction and expansion structure in the airflow channel, such as... Figure 12 As shown, air mixes along the flow direction, which helps to block the development of the air-side boundary layer and reduce uneven temperature distribution, thereby improving heat exchange efficiency. The outer surface of the flat tube is smooth and finless. The welded flat tube sidewall of the collector slopes downwards towards the airflow direction. Under the combined action of wind and gravity, this effectively improves drainage performance, ensuring drainage and defrosting performance. Furthermore, the simple air channel structure reduces the pressure drop on the air side and the difficulty of processing and manufacturing.

[0084] The microchannel flat tube 6 has multiple parallel flow channels inside, with a total flow channel length of 228 mm. The flow channels are "D" shaped at both ends and "U" shaped in the middle. The flow channel orifice height is (…). Figure 9The vertical direction shown is 0.35mm, and the hole width is (…). Figure 9 The diameter (left-right direction shown) is 0.59 mm, and the hole spacing is 0.79 mm. The microchannel orifice size is further reduced compared to the current mainstream microchannel size, and the number of channels on the flat tube is greater. This reduces refrigerant usage, and the parallel arrangement of the front and rear collectors improves channel blockage and enhances operational reliability. The heat transfer coefficient of the microchannel increases significantly with decreasing diameter. Compared to larger diameter channels, the boundary layer of the microchannel is thinner, resulting in stronger convective heat transfer, more significant heat transfer effect, and better air heat transfer. Utilizing microchannel heat exchange can effectively reduce the overall size of the heat exchanger, ensure normal operation, and improve heat transfer efficiency.

[0085] like Figure 2 , Figure 10 and 11 As shown, the inlet-side support plate is located on the outermost side of the microchannel flat tube and is parallel to the tube. The front support plate on the inlet side is 16mm wide and 1.5mm thick, and the rear support plate on the inlet side is 12mm wide and 1.5mm thick. The front and rear support plates are arranged parallel to each other in the same horizontal plane, with a total width of 35.5mm. The inlet-side and outlet-side support plates are located on the outer side of the microchannel flat tube 6 and are arranged parallel to the tube. They support the upper and lower collectors, reduce the pressure on the flat tube, thereby reducing the risk of deformation and damage to the flat tube and improving the stability and practicality of the entire heat exchanger system.

[0086] Figure 12 and Figure 13 These are, respectively, the streamline distribution diagram and the temperature contour map of the heat exchanger in this embodiment. From Figure 12 It can be seen that after the airflow passes through the microchannel flat tube, a vortex core region is formed at the tail of the flat tube. Figure 13 The airflow is characterized by localized high-temperature areas. Due to the staggered arrangement of the flat tubes, the airflow lines exhibit abrupt expansion and contraction, and the airflow lines undergo intense mixing after passing through each row of flat tubes, further enhancing the heat exchange between the hot and cold fluids. Figure 13 The cooling air has the highest temperature near the wall and gradually decreases as it moves away from the wall. Each row of microchannel flat tubes has a tail-like temperature transition zone at the end, and the tail-like area at the end of the rear row gradually increases with the direction of the wind.

[0087] Figure 14This section compares the performance of the heat exchanger in this embodiment with existing conventional heat exchangers. D7 and D5, as conventional tube-fin heat exchangers, are widely used in various heat exchanger devices. Through numerical simulations of four actual operating conditions, the same inlet and outlet cross-sections were selected to compare the two important indicators: temperature difference and pressure difference. As shown in the figure, for all three heat exchangers, the inlet and outlet temperature difference decreases with increasing air-side inlet velocity, while the inlet and outlet pressure difference continuously increases with increasing air-side inlet velocity. Compared to the D7 and D5 heat exchangers, the high-efficiency composite three-row microchannel heat exchanger shows an average increase of 14.3% and 11.2% in inlet and outlet temperature differences, respectively, under the four operating conditions; simultaneously, the high-efficiency composite three-row microchannel heat exchanger shows an average increase of 5.5% and 7.4% in inlet and outlet pressure differences, respectively, compared to the D7 and D5 heat exchangers, under the four operating conditions. The heat exchange efficiency of the high-efficiency composite three-row microchannel heat exchanger gradually increases with increasing inlet air velocity under four simulated operating conditions. Specifically, at an inlet air velocity of 0.8 m / s, the inlet and outlet temperature difference of heat exchanger D7 is 20.06 K and that of heat exchanger D5 is 20.07 K. Under this condition, the inlet and outlet temperature difference of the high-efficiency composite three-row microchannel heat exchanger is only 20.97 K, representing an improvement of 4.6% and 4.5% compared to heat exchangers D7 and D5, respectively. At an inlet air velocity of 2.3 m / s, the inlet and outlet temperature difference of heat exchanger D7 is 12.17 K and that of heat exchanger D5 is 12.81 K. Under this condition, the inlet and outlet temperature difference of the high-efficiency composite three-row microchannel heat exchanger is 15.10 K, representing an improvement of 24.1% and 17.8% compared to heat exchangers D7 and D5, respectively. The inlet and outlet pressure difference of the high-efficiency composite three-row microchannel heat exchanger increased less than that of the D7 and D5 heat exchangers under four operating conditions. Except for the D5 heat exchanger under the condition of 0.8 m / s inlet wind speed, the percentage increase of the inlet and outlet temperature difference was higher than the percentage increase of the inlet and outlet pressure difference under the remaining operating conditions.

[0088] Example 2

[0089] Please see Figure 15 , Figure 16 and Figure 17 In this embodiment, the high-efficiency composite multi-row microchannel heat exchanger is provided with two rows of microchannel flat tubes, including an upper collector 1, a lower collector 7, several microchannel flat tubes 6 and other auxiliary accessories.

[0090] The upper collector 1 is located above the lower collector 7, and the upper collector 1 and the lower collector 7 are connected by several microchannel flat tubes 6. These microchannel flat tubes 6 are inserted into the upper and lower collector assemblies at a 90° angle to the horizontal plane. The vertical 90° arrangement of the microchannel flat tubes helps to reduce water droplet adhesion to the walls of the microchannel flat tubes 6 under gravity, thereby improving the occurrence of frost and condensation in humid conditions.

[0091] The upper collector 1 has heat exchanger inlet and outlet pipes on both vertical end faces, with refrigerant inlet pipe section 2 on the right end face and refrigerant outlet pipe section 3 on the left end face. Both inlet pipe section 2 and outlet pipe section 3 are circular pipes with an inner diameter of 9.7 mm and a wall thickness of 0.8 mm.

[0092] The upper collector 1 and the lower collector 7 are connected by several parallel microchannel flat tubes 6, with the longitudinal axis of the microchannel flat tubes 6 perpendicular to the horizontal plane. The microchannel flat tubes are arranged in two staggered rows. Within the same flow path, the spacing between the flat tubes is 1.9 mm. The spacing between adjacent flat tubes in the first row is 3.8 mm, and the spacing between adjacent flat tubes in the second row is 5.7 mm. The vertical projection of each flat tube within the same flow path is located at the center of the spacing between two tubes in the other row, with a row spacing of 12.75 mm. Unlike a single-row arrangement, the double-row staggered arrangement intensifies the exchange of hot and cold air and expands the heat exchange area. The smaller the spacing between the flat tubes, the better the turbulence effect, the larger the heat transfer coefficient, and the more significant the heat exchange effect, resulting in better air heat exchange. The microchannel flat tubes consist of 194 parallel flat tubes. The first row of microchannel flat tubes has a flat tube ratio of 22:27:27:22 in the four process areas, while the second row of flat tubes has a flat tube ratio of 22:26:26:22 in the four process areas.

[0093] The projection of the first row of microchannel flat tubes on the horizontal plane is parallel to the direction of the short side, and the center of the outermost microchannel flat tube is 11mm away from the short sides of both sides of the collector. The projection of the second row of microchannel flat tubes on the horizontal plane is parallel to the direction of the short side, and the center of the outermost microchannel flat tube is 10.05mm away from the short sides of both sides of the collector.

[0094] like Figure 18 and Figure 19 As shown, both the upper collector 1 and the lower collector 7 are equipped with baffles. The upper collector 1 has two baffles (upper collector inlet baffle 1012 and upper collector outlet baffle 1022) located at 1 / 4 and 3 / 4 of its length, respectively. The lower collector 7 has one baffle (i.e., lower collector baffle 7011) located at 1 / 2 of its length. By setting these baffles, the microchannel flat tube 6 is divided into four regions within the collector, forming multiple U-shaped refrigerant flow paths (i.e., the serpentine pathways) with upward and downward "U"-shaped flow, allowing the refrigerant to flow through multiple paths and achieve sufficient heat exchange. Specifically, the refrigerant flow direction is as follows: Figure 20 As shown.

[0095] As shown in Figures 21(a), 21(b), 22(a) and 22(b), both the upper collector 1 and the lower collector 7 are rectangular tubes; several microchannel flat tubes 6 are evenly and regularly inserted into the upper and lower collectors. Considering the processing difficulty and versatility, the insertion depth accounts for 1 / 2 of the height of the cavity inside the collector.

[0096] like Figure 23 As shown, the microchannel flat tube 6 is a straight flat tube with a width of 10.75 mm and rounded corners on both sides. Its thickness is 0.7 mm, which is beneficial for improving the air-side heat transfer coefficient. This is mainly achieved by increasing the air-side heat transfer area and blocking the development of the air-side boundary layer. Therefore, the microchannel flat tube 6 is arranged in two rows in a staggered pattern and inserted into the collector. Simultaneously, this creates a sudden contraction and expansion structure in the airflow channel, as shown... Figure 24 As shown, air mixes along the flow direction, which helps to block the development of the air-side boundary layer and reduce uneven temperature distribution, thereby improving heat exchange efficiency. The outer surface of the flat tube is smooth and finless. The welded flat tube sidewall of the collector slopes downwards towards the airflow direction. Under the combined action of wind and gravity, this effectively improves drainage performance, ensuring drainage and defrosting performance. Furthermore, the simple air channel structure reduces the pressure drop on the air side and the difficulty of processing and manufacturing.

[0097] The microchannel flat tube 6 contains multiple parallel flow channels, with a total length of 228 mm. The flow channels are D-shaped at both ends and U-shaped in the middle. The channel height is 0.22 mm, the width is 0.67 mm, and the spacing is 0.94 mm. The microchannel orifice size is further reduced compared to current mainstream microchannel sizes, and the increased number of channels on the flat tube reduces refrigerant usage. Furthermore, the double-row staggered arrangement of the flat tubes improves channel blockage and enhances operational reliability. The heat transfer coefficient of the microchannel increases significantly with decreasing diameter. Compared to larger diameter channels, the boundary layer of the microchannel is thinner, resulting in stronger convective heat transfer and a more significant heat exchange effect, particularly for air. Utilizing microchannel heat exchange can effectively reduce the overall size of the heat exchanger, ensure normal operation, and improve heat exchange efficiency.

[0098] like Figure 15 and Figure 16 As shown, a support plate is provided on the outside of the microchannel flat tube 6. The support plate is 25.4 mm wide, 1.5 mm thick, and 212 mm long. The two support plates are located on the outside of the microchannel flat tube 6 and are arranged parallel to the microchannel flat tube 6. They support the upper and lower collectors, reduce the pressure on the flat tube, thereby reducing the risk of deformation and damage to the flat tube and improving the stability and practicality of the entire heat exchanger system.

[0099] Figure 24 and Figure 25 These are, respectively, the streamline distribution diagram and the temperature contour map of the heat exchanger in this embodiment. From Figure 24 It can be seen that after the airflow passes through the microchannel flat tube, a vortex core region is formed at the tail of the flat tube. Figure 25The airflow is characterized by localized high-temperature areas. Due to the staggered arrangement of the flat tubes, the airflow lines exhibit abrupt expansion and contraction, and the airflow lines undergo intense mixing after passing through each row of flat tubes, further enhancing the heat exchange between the hot and cold fluids. Figure 25 The cooling air has the highest temperature near the wall and gradually decreases as it moves away from the wall. Each row of microchannel flat tubes has a tail-like temperature transition zone at the end, and the tail-like area at the end of the rear row gradually increases with the direction of the wind.

[0100] Figure 26 This section compares the performance of the heat exchanger in this embodiment with that of existing conventional heat exchangers. D7 and D5, as conventional tube-fin heat exchangers, are widely used in various heat exchanger systems. Through numerical simulations of four actual operating conditions, the same inlet and outlet cross-sections were selected to compare two important indicators: temperature difference and pressure difference. Figure 26 As shown, for the three types of heat exchangers, the inlet and outlet temperature difference decreases with increasing air inlet velocity, while the inlet and outlet pressure difference increases continuously with increasing air inlet velocity. In this embodiment, the microchannel heat exchanger, compared to the D7 and D5 heat exchangers, shows an average increase of 12.4% and 9.4% in inlet and outlet temperature differences, respectively, under the same operating conditions. Simultaneously, the high-efficiency composite double-row microchannel heat exchanger shows an average increase of 6.7% and 8.6% in inlet and outlet pressure differences, respectively, compared to the D7 and D5 heat exchangers, under the same operating conditions. The heat exchange efficiency of the new high-efficiency composite double-row microchannel heat exchanger gradually improves with increasing inlet air velocity under four simulated operating conditions. Specifically, at an inlet air velocity of 0.8 m / s, the inlet and outlet temperature difference of the D7 heat exchanger is 20.06 K, and that of the D5 heat exchanger is 20.07 K. Under this condition, the inlet and outlet temperature difference of the high-efficiency composite double-row microchannel heat exchanger is only 21.18 K, representing increases of 5.6% and 5.5%, respectively, compared to the D7 and D5 heat exchangers. At an inlet air velocity of 2.3 m / s, the inlet and outlet temperature difference of heat exchanger D7 is 12.17 K, and that of heat exchanger D5 is 12.81 K. Under this condition, the inlet and outlet temperature difference of the high-efficiency composite double-row microchannel heat exchanger is 14.49 K, which is approximately 19.1% and 13.1% higher than that of heat exchangers D7 and D5, respectively. The percentage increase in inlet and outlet temperature difference and the percentage increase in inlet and outlet pressure difference of the high-efficiency composite double-row microchannel heat exchanger are relatively similar at an inlet air velocity of 1.3 m / s. However, at higher inlet air velocities of 1.8 m / s and 2.3 m / s, the percentage increase in inlet and outlet temperature difference is higher than the percentage increase in inlet and outlet pressure difference.

[0101] Example 3

[0102] Please see Figure 27 , Figure 28 and Figure 29 As shown in the figure, the high-efficiency composite multi-row microchannel heat exchanger in this embodiment is provided with two rows of microchannel flat tubes, including an upper collector 1, a lower collector 7, several microchannel flat tubes 6 and other auxiliary accessories.

[0103] The upper collector 1 is located above the lower collector 7, and the upper collector 1 and the lower collector 7 are connected by several microchannel flat tubes 6. These microchannel flat tubes 6 are inserted into the upper and lower collector assemblies at a 90° angle to the horizontal plane. The vertical 90° arrangement of the microchannel flat tubes helps to reduce water droplet adhesion to the walls of the microchannel flat tubes 6 under gravity, thereby improving the occurrence of frost and condensation in humid conditions.

[0104] The upper collector 1 has heat exchanger inlet and outlet pipes on both vertical end faces, with refrigerant inlet pipe section 2 on the right end face and refrigerant outlet pipe section 3 on the left end face. Both inlet pipe section 2 and outlet pipe section 3 are circular pipes with an inner diameter of 9.7 mm and a wall thickness of 0.8 mm.

[0105] The upper collector 1 and the lower collector 7 are connected by several parallel microchannel flat tubes 6, with the longitudinal axis of the microchannel flat tubes 6 perpendicular to the horizontal plane. The microchannel flat tubes are arranged in two staggered rows, with a tube spacing of 2mm within the same flow path. The tube spacing between adjacent flow paths of the first and second rows alternates between 4mm and 6mm. The vertical projection of each flat tube within the same flow path is located at the center of the tube spacing of the other row, with a row spacing of 14mm. Unlike a single-row arrangement, the double-row staggered arrangement intensifies the exchange of hot and cold air and expands the heat exchange area. Smaller tube spacing results in better turbulence, a higher heat transfer coefficient, and a more significant heat exchange effect, leading to better air heat exchange. The microchannel flat tubes consist of 184 parallel flat tubes. In the first row, the number of microchannel flat tubes is the same in all four flow areas, with a tube ratio of 22:25:25:22.

[0106] The projection of the first row of microchannel flat tubes on the horizontal plane is parallel to the direction of the short side, and the center of the outermost microchannel flat tube is 10mm away from the short sides of both sides of the collector. The projection of the second row of microchannel flat tubes on the horizontal plane is parallel to the direction of the short side, and the center of the outermost microchannel flat tube is 11mm away from the short sides of both sides of the collector.

[0107] like Figure 30 and Figure 31 As shown, both the upper collector 1 and the lower collector 7 are equipped with baffles. The upper collector 1 has two baffles (upper collector inlet baffle 1012 and upper collector outlet baffle 1022) located at 1 / 4 and 3 / 4 of its length, respectively. The lower collector 7 has one baffle (i.e., lower collector baffle 7011) located at 1 / 2 of its length. By setting the baffles, the microchannel flat tube 6 is divided into four regions within the collector, forming multiple U-shaped refrigerant flow paths with vertical "U"-shaped flow, allowing for multi-pass refrigerant flow and sufficient heat exchange. Specifically, the refrigerant flow direction is the same as in Example 2. Figure 20 same.

[0108] The structures of the upper collector 1 and the lower collector 7 in this embodiment are basically the same as those in embodiment 2. Refer to Figures 21(a), 21(b), 22(a) and 22(b). Both the upper collector 1 and the lower collector 7 are rectangular tubes. Several microchannel flat tubes 6 are evenly and regularly inserted into the upper and lower collectors. Considering the difficulty of processing and versatility, the insertion depth accounts for 1 / 2 of the height of the cavity inside the collector.

[0109] The microchannel flat tube 6 is a straight flat tube with a width of 12mm and rounded corners on both sides. Its thickness is 0.7mm, which helps to improve the air-side heat transfer coefficient. This is mainly achieved by increasing the air-side heat transfer area and inhibiting the development of the air-side boundary layer. Therefore, the microchannel flat tube 6 is arranged in two rows in a staggered pattern and inserted into the collector. Simultaneously, this creates a sudden contraction and expansion structure in the airflow channel, such as... Figure 32 As shown, air mixes along the flow direction, which helps to block the development of the air-side boundary layer and reduce uneven temperature distribution, thereby improving heat exchange efficiency. The outer surface of the flat tube is smooth and finless. The welded flat tube sidewall of the collector slopes downwards towards the airflow direction. Under the combined action of wind and gravity, this effectively improves drainage performance, ensuring drainage and defrosting performance. Furthermore, the simple air channel structure reduces the pressure drop on the air side and the difficulty of processing and manufacturing.

[0110] The microchannel flat tube 6 contains multiple parallel flow channels, with a total length of 228 mm. The flow channels are D-shaped at both ends and U-shaped in the middle. The channel height is 0.22 mm, the width is 0.68 mm, and the spacing is 0.94 mm. The microchannel orifice size is further reduced compared to current mainstream microchannel sizes, and the increased number of channels on the flat tube reduces refrigerant usage. Furthermore, the double-row staggered arrangement of the flat tubes improves channel blockage and enhances operational reliability. The heat transfer coefficient of the microchannel increases significantly with decreasing diameter. Compared to larger diameter channels, the boundary layer of the microchannel is thinner, resulting in stronger convective heat transfer and a more significant heat exchange effect, particularly for air. Utilizing microchannel heat exchange can effectively reduce the overall size of the heat exchanger, ensure normal operation, and improve heat exchange efficiency.

[0111] like Figure 27 and Figure 28As shown, a support plate is provided on the outside of the microchannel flat tube 6. The support plate is 12mm wide, 1.5mm thick, and 212mm long. Two support plates are arranged on the same horizontal plane on both the inlet and outlet sides, with a total width of 26mm. A total of four support plates are located on the outside of the microchannel flat tube 6, arranged parallel to the microchannel flat tube 6. They support the upper and lower collectors, reduce the pressure on the flat tube, thereby reducing the risk of deformation and damage to the flat tube, and improving the stability and practicality of the entire heat exchanger system.

[0112] Figure 32 and Figure 33 These are, respectively, the streamline distribution diagram and the temperature contour map of the microchannel heat exchanger in this embodiment. Figure 32 It can be seen that after the airflow passes through the microchannel flat tube, a vortex core region is formed at the tail of the flat tube. Figure 33 The airflow is characterized by localized high-temperature areas. Due to the staggered arrangement of the flat tubes, the airflow lines exhibit abrupt expansion and contraction, and the airflow lines undergo intense mixing after passing through each row of flat tubes, further enhancing the heat exchange between the hot and cold fluids. Figure 33 The cooling air has the highest temperature near the wall and gradually decreases as it moves away from the wall. Each row of microchannel flat tubes has a tail-like temperature transition zone at the end, and the tail-like area at the end of the rear row gradually increases with the direction of the wind.

[0113] Figure 34This document compares the performance of the microchannel heat exchanger in this embodiment with that of existing conventional heat exchangers. D7 and D5, as conventional tube-fin heat exchangers, are widely used in various heat exchanger devices. Through numerical simulations of four actual operating conditions, the same inlet and outlet cross-sections were selected to compare the two important indicators: temperature difference and pressure difference. As shown in the figure, for all three heat exchangers, the inlet and outlet temperature difference decreases with increasing air-side inlet velocity, while the inlet and outlet pressure difference continuously increases with increasing air-side inlet velocity. Compared to the D7 and D5 heat exchangers, the microchannel heat exchanger in this embodiment increases the inlet and outlet temperature difference by an average of 11.4% and 8.4% under the same operating conditions, respectively. Simultaneously, compared to the D7 heat exchanger, the new high-efficiency composite double-row microchannel heat exchanger reduces the inlet and outlet pressure difference by an average of 1.5% under the same operating conditions, while maintaining roughly the same inlet and outlet pressure drop as the D5 heat exchanger, with a slight increase of 0.2%. The high-efficiency composite double-row microchannel heat exchanger showed a progressively increasing heat exchange efficiency with increasing inlet air velocity under four simulated operating conditions. Specifically, at an inlet air velocity of 0.8 m / s, the inlet and outlet temperatures were 5.1% higher than those of the D7 heat exchanger and 5.0% higher than those of the D5 heat exchanger; at an inlet air velocity of 1.3 m / s, the inlet and outlet temperatures were 8.7% higher than those of the D7 heat exchanger and 6.9% higher than those of the D5 heat exchanger; at an inlet air velocity of 1.8 m / s, the inlet and outlet temperatures were 13.8% higher than those of the D7 heat exchanger and 9.6% higher than those of the D5 heat exchanger; and at an inlet air velocity of 2.3 m / s, the inlet and outlet temperatures were 18.0% higher than those of the D7 heat exchanger and 12.1% higher than those of the D5 heat exchanger. Except for the inlet and outlet pressure difference being higher than that of the D7 heat exchanger at an inlet air velocity of 0.8 m / s, the inlet and outlet pressure drops of the high-efficiency composite double-row microchannel heat exchanger were superior to those of the D7 heat exchanger under all other operating conditions. Compared with the D5 heat exchanger, the high-efficiency composite double-row microchannel heat exchanger also exhibits superior inlet and outlet pressure drop under high inlet air velocity conditions.

[0114] It should be noted that, in this document, terms such as “comprising,” “including,” or any other variations are intended to cover non-exclusive inclusion, such that an article or device comprising a list of elements includes not only those elements but also other elements not expressly listed. Without further limitations, an element defined by the phrase “comprising…” does not exclude the presence of other identical elements in the article or device comprising said element. Terms such as “connected” or “linked” are not limited to physical or mechanical connections but can include electrical connections, whether direct or indirect. The orientations or positional relationships indicated by terms such as “up,” “down,” “left,” and “right” are based on the orientations or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the invention.

[0115] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A high-efficiency composite multi-row microchannel heat exchanger, characterized in that, It includes an upper collector (1), and a lower collector (7) is provided parallel below the upper collector (1). At least two rows of microchannel flat tubes are provided between the upper collector (1) and the lower collector (7). Each row of microchannel flat tubes includes several groups of microchannel flat tubes. The upper end of each group of microchannel flat tubes is connected to the upper collector (1) and the lower end is connected to the lower collector (7). In two adjacent rows of microchannel flat tubes, the number of microchannel flat tube groups is the same. The microchannel flat tube groups in two adjacent rows of microchannel flat tubes are arranged opposite each other. Each microchannel flat tube group contains multiple parallel microchannel flat tubes with smooth sidewall surfaces (6). In two adjacent rows of microchannel flat tubes, the microchannel flat tubes (6) in the microchannel flat tube groups are staggered, and the microchannel flat tube (6) in one microchannel flat tube group is opposite to the gap between two adjacent microchannel flat tubes (6) in another microchannel flat tube group; Each microchannel flat tube (6) is provided with multiple parallel flow channels, the upper end of which is connected to the upper collector (1) and the lower end of which is connected to the lower collector (7); The flow channels located at both ends of the microchannel flat tube (6) in the width direction are D-shaped tubes, with one side of the curved surface of the D-shaped tube facing the outside of the end of the microchannel flat tube (6) in the width direction. The remaining flow channels in the microchannel flat tube (6) are rectangular tubes. Both the upper collector (1) and the lower collector (7) are equipped with a flow divider baffle. The flow divider baffle is located at the junction between two adjacent microchannel flat tube groups. The flow divider baffle in the upper collector (1) and the flow divider baffle in the lower collector (7) make the several groups of microchannel flat tube groups connected in sequence to form a serpentine path. The upper collector (1) is provided with a refrigerant inlet and a refrigerant outlet at both ends; or the upper collector (1) is provided with a refrigerant inlet and the lower collector (7) is provided with a refrigerant outlet; or the upper collector (1) is provided with a refrigerant outlet and the lower collector (7) is provided with a refrigerant inlet; or the lower collector (7) is provided with a refrigerant inlet and a refrigerant outlet at both ends; the refrigerant inlet and the refrigerant outlet are respectively connected to the two ends of the serpentine passage.

2. The high-efficiency composite multi-row microchannel heat exchanger according to claim 1, characterized in that, When there are more than three rows of microchannel flat tubes, the microchannel flat tubes (6) in the microchannel flat tube group set opposite each other in the two rows of microchannel flat tubes are set opposite each other.

3. The high-efficiency composite multi-row microchannel heat exchanger according to claim 1, characterized in that, When there are three or more rows of microchannel flat tubes, all rows of microchannel flat tubes are sequentially denoted as the (n-1)th row of microchannel flat tubes, the nth row of microchannel flat tubes, the (n+1)th row of microchannel flat tubes, and so on. The distance between the (n-1)th row of microchannel flat tubes and the nth row of microchannel flat tubes is less than the distance between the nth row of microchannel flat tubes and the (n+1)th row of microchannel flat tubes, where n is a positive integer greater than or equal to 2.

4. The high-efficiency composite multi-row microchannel heat exchanger according to claim 1, characterized in that, In two adjacent rows of microchannel flat tubes, the microchannel flat tube groups in one row are arranged at equal intervals of spacing A, while the microchannel flat tube groups in the other row are arranged alternately at two intervals of spacing B and spacing C, wherein spacing A ≤ spacing B < spacing C.

5. A high-efficiency composite multi-row microchannel heat exchanger according to claim 1, characterized in that, In each group of microchannel flat tubes, the distance between adjacent microchannel flat tubes (6) is 1.9-2mm; the distance between two adjacent groups of microchannel flat tubes is 4-6mm; and the distance between two adjacent rows of microchannel flat tubes is 9-15mm.

6. The high-efficiency composite multi-row microchannel heat exchanger according to claim 1, characterized in that, The width of the flow channel cross section is 0.20-0.35mm, the length is 0.55-0.70mm, and the spacing between adjacent flow channels is 0.79-0.94mm; wherein, the width direction of the flow channel cross section is the thickness direction of the microchannel flat tube (6), and the length direction of the flow channel cross section is the width direction of the microchannel flat tube (6).

7. The high-efficiency composite multi-row microchannel heat exchanger according to claim 1, characterized in that, The microchannel flat tube (6) is a straight flat tube with a width of 7-12mm and a thickness of 0.65-0.75mm; both ends of the microchannel flat tube (6) along the width direction are rounded.

8. A high-efficiency composite multi-row microchannel heat exchanger according to claim 1, characterized in that, Four groups of microchannel flat tubes are set in each row of microchannel flat tubes. The ratio of the number of microchannel flat tubes (6) in the four groups of microchannel flat tubes is (21-23): (25-27): (25-27): (21-23).

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