Capillary micro-channel heat exchanger capable of reducing flow resistance and preparation method of capillary micro-channel heat exchanger

Abstract

The invention discloses a capillary microchannel heat exchanger capable of reducing flow resistance and a preparation method of the capillary microchannel heat exchanger, and relates to the technical field of heat exchange equipment. The hot layer sets and the cold layer sets are sequentially arranged in a staggered and stacked mode and are separated through partition plates. Each of the cold layer group and the hot layer group comprises an inlet section group, a buffer confluence cavity and an outlet section group; the buffer confluence cavity is positioned between the inlet section group and the outlet section group; and nickel-plated phosphorus coatings are arranged on the inlet capillary tubes arranged in the inlet section group and the outlet capillary tubes arranged in the outlet section group. The preparation method comprises the following steps: S1, obtaining various parameters of related equipment through simulation calculation; s2, assembling the single layer according to the obtained parameters, and spraying a nickel-phosphorus plating coating; s3, sequentially arranging the interlayers; and S4, vacuum diffusion welding is conducted after overall assembly is completed, and the performance of the heat exchanger is tested. Through the arrangement, flow resistance can be effectively reduced, and heat exchange efficiency is improved.

Description

Technical Field

[0001] The invention relates to the technical field of heat exchange equipment, and in particular to a capillary microchannel heat exchanger with reduced flow resistance and a preparation method thereof. Background Art

[0002] With the rapid development of modern industry and technology, the requirements for heat exchange efficiency, compactness and pressure resistance of heat exchangers are becoming more and more stringent. Due to the large channel size and relatively limited heat exchange area of ​​traditional heat exchangers, it is difficult to improve the heat exchange efficiency, and its large size cannot meet the needs of specific scenarios such as miniaturization of heat dissipation of electronic equipment and lightweight aerospace equipment. At a time when heat exchange technology is booming, capillary microchannel heat exchangers have emerged as a hot research object in the field of scientific research and industrial applications. With its unique structural design, it has unlocked a new path for efficient heat exchange and is quietly reshaping the thermal management landscape of multiple industries.

[0003] However, the existing capillary microchannel heat exchanger has a problem of large flow resistance, which affects the heat exchange efficiency. Therefore, it is particularly important to provide a capillary microchannel heat exchanger that can reduce the flow resistance. Summary of the invention

[0004] The purpose of the present invention is to provide a capillary microchannel heat exchanger with reduced flow resistance and a preparation method thereof, so as to solve the problems existing in the above-mentioned prior art, and to effectively reduce flow resistance and improve heat exchange efficiency.

[0005] To achieve the above object, the present invention provides the following solutions: The present invention provides a capillary microchannel heat exchanger for reducing flow resistance, comprising a plurality of hot layer groups and a plurality of cold layer groups; each of the hot layer groups and each of the cold layer groups are arranged in an alternate and stacked manner; the hot layer group is separated from the adjacent cold layer group by a partition; each of the cold layer group and each of the hot layer groups contains a fluid medium for circulating heat exchange; the cold layer group and the hot layer group each include an inlet section group, a buffer confluence cavity and an outlet section group; the buffer confluence cavity is located between the inlet section group and the outlet section group; the inlet section group includes a plurality of inlet capillaries arranged in sequence, and the outlet end of each inlet capillary is connected to the buffer confluence cavity; the outlet section group includes a plurality of outlet capillaries arranged in sequence, and the inlet end of each outlet capillary is connected to the buffer confluence cavity; the inlet capillaries correspond to the outlet capillaries one by one; the overall outer side walls of the arranged inlet capillaries and the arranged outlet capillaries are sprayed with a nickel-phosphorus coating.

[0006] Preferably, the distance between the outlet end of the inlet capillary and the inlet end of the corresponding outlet capillary of the buffer confluence cavity is 0.1 mm to 3 mm.

[0007] Preferably, the inlet end of the inlet capillary is bent toward a side close to the inflow of the fluid medium, and the outlet end of the outlet capillary is bent toward a side close to the outflow of the fluid medium.

[0008] Preferably, in the projection direction of the partition, the buffer confluence cavity of the cold layer group and the buffer confluence cavity of the adjacent hot layer group are arranged in a staggered manner.

[0009] Preferably, the angle between the axis of the inlet end of the inlet capillary and the axis of the outlet end of the inlet capillary is set to a first bending angle; the angle between the axis of the outlet end of the outlet capillary and the axis of the inlet end of the outlet capillary is set to a second bending angle; the range of the first bending angle and the second bending angle is 0°~180°.

[0010] Preferably, the flow form of the fluid medium in the hot layer group and the fluid medium in the adjacent cold layer group is countercurrent or crossflow.

[0011] Preferably, the wall thickness of the inlet capillary and the outlet capillary are both 0.1 mm to 0.5 mm.

[0012] Preferably, along the arrangement direction of each inlet capillary or each outlet capillary, closed baffles are respectively provided at both ends of the space between the inlet section group and the outlet section group; the space between the inlet section group and the outlet section group and the two closed baffles and the corresponding partitions together enclose the buffer confluence cavity.

[0013] Preferably, the inner walls of the inlet capillary and the outlet capillary are smooth.

[0014] The present invention also provides a method for preparing a capillary microchannel heat exchanger with reduced flow resistance based on any one of the above items, comprising the following steps: S1, obtaining the optimal flow form of the heat exchanger, the number of layers of the hot layer group and the cold layer group, the wall thickness of each inlet capillary and each outlet capillary, and the corresponding size data of the buffer confluence cavity through one-dimensional flow resistance calculation and three-dimensional fluid simulation calculation; S2, assembling the inlet section group and the outlet section group in each layer in turn by layer; wherein, firstly arranging the inlet capillaries of the inlet section group in accordance with the required number, spraying the corresponding nickel-phosphorus coating on the outer side wall thereof as a whole, and then arranging the outlet capillaries of the outlet section group in accordance with the required number, spraying the corresponding nickel-phosphorus coating on the outer side wall thereof as a whole according to the corresponding size of the buffer confluence cavity obtained in S1; or, firstly preparing the outlet section group, spraying the corresponding nickel-phosphorus coating on the outer side wall thereof as a whole, and then preparing the inlet section group according to the corresponding size of the buffer confluence cavity obtained in S1, and spraying the corresponding nickel-phosphorus coating on the outer side wall thereof; S3, laying the hot layer group or the cold layer group of the next adjacent layer according to the optimal flow form obtained in S1; S4, after assembling to the required number of layers, the whole is vacuum diffusion welded and the heat exchanger performance test is performed.

[0015] Compared with the prior art, the present invention has achieved the following technical effects: The capillary microchannel heat exchanger with reduced flow resistance provided by the present invention has a buffer confluence cavity set between the inlet section group and the outlet section group, where the fluid flowing out of the inlet capillary first converges. When the fluid is ejected from multiple small inlet capillaries at high speed, it will carry a large kinetic energy and a turbulent flow velocity distribution. The buffer confluence cavity plays the role of a "speed bump" and a "rectifier", which reduces the fluid velocity and redistributes it evenly, and then flows smoothly into the outlet capillary. Compared with the traditional single flow channel layout, it can significantly reduce the resistance of subsequent flow; in the buffer confluence cavity, the fluids transported from different inlet capillaries are fully mixed, and the temperature is more uniform. The uniformity of the flow is increased, and the temperature difference with the adjacent layers is more fully utilized. When this uniform fluid flows into the outlet capillary to exchange heat with the fluid on the other side, the heat exchange efficiency will be improved due to the more regular temperature field; the smaller gaps between the arranged inlet capillaries or outlet capillaries can be filled with the sprayed nickel-phosphorus coating, leaving only a larger flow space outside the tube, reducing the resistance of the fluid flowing in the gaps outside the tube, and the surface of the nickel-phosphorus coating is smooth, so that the flow resistance of the flow channel outside the tube can also be reduced, so that the fluid can pass more smoothly, effectively reducing the flow resistance; based on the above measures, it can effectively reduce the flow resistance and improve the heat exchange efficiency.

[0016] Furthermore, the spacing is set between 0.1mm and 3mm. If the spacing is too small, the convergence effect cannot be achieved, while if the spacing is too large, the overall performance of the heat exchanger will be reduced. Within this spacing range, when the fluids from different inlet capillaries converge in the buffer convergence cavity, the heat exchange is more sufficient. The appropriate spacing can reduce the "dead zone" in the buffer convergence cavity. The so-called dead zone is an area where the fluid flow is slow and hardly participates in heat exchange. If the spacing is too large, a dead zone is easily formed, and the fluid stagnates in it for a long time, and heat cannot be effectively transferred. The spacing within the limited range keeps the fluid in an active flow state at all times, eliminating the dead zone and ensuring the efficiency of the entire heat exchange process.

[0017] Furthermore, the curved design of the inlet end of the inlet capillary allows the incoming fluid medium to enter the inlet capillary more smoothly along the curved contour, and the curved outlet end of the outlet capillary allows the outflowing fluid to gradually accelerate and spread to the downstream along the curved direction; the curvature of the inlet will cause the fluid to form a certain swirl or biased flow when entering the capillary. This special flow state will make the flow path of the fluid in the capillary more complicated, no longer a simple straight line, and in disguised form extend the residence time of the fluid in the capillary. The longer residence time means more opportunities for sufficient heat exchange with the tube wall, thereby improving the heat exchange degree of a single pass.

[0018] Furthermore, if the buffer confluence cavities of each layer are all concentrated in one area, force transmission welding cannot be effectively performed here during diffusion welding. By adopting a staggered arrangement, defects caused by the inability to transmit force during diffusion welding can be effectively avoided.

[0019] Furthermore, the bending angle is the key to optimization. The bending angle is determined according to the viscosity and pressure of the medium used. If the angle is too small, the flow state of the fluid may not be effectively changed, and the effect of reducing the flow resistance is not obvious. If the angle is too large, it may cause fluid flow disorder, vortex and backflow, which will increase the flow resistance. Therefore, from the perspective of the overall system, a collaborative optimization method of multiple bending angles is adopted to ensure that the flow resistance is reduced and the heat exchange effect is improved.

[0020] Furthermore, in the countercurrent state, the flow directions of the hot fluid and the cold fluid are completely opposite. The hot fluid has the highest temperature when it just enters the heat exchanger, and the cold fluid it meets has the lowest temperature at this time. The temperature difference between the two is extremely large, which provides a strong driving force for heat transfer; as the heat exchange process progresses, the temperature of the hot fluid gradually decreases, and the temperature of the cold fluid gradually increases, but the temperature difference throughout the process can always be maintained at a relatively considerable level. This continuous and strong temperature difference utilization enables the countercurrent heat exchanger to obtain more heat exchange than other flow forms under the same heat exchange area, fluid flow rate and inlet and outlet temperature conditions, and the heat exchange efficiency is significantly improved; in the cross flow, the flow directions of the hot and cold fluids are perpendicular to each other. This layout makes the overall structural design of the heat exchanger more diverse and flexible. Engineers can easily adjust the direction and arrangement of the hot and cold fluid channels according to the shape and size of the actual installation space to adapt to the compact and special-shaped installation requirements of different equipment; the flow form can be selected according to actual conditions.

[0021] Furthermore, the setting of the wall thickness range can minimize the additional flow resistance caused by wall thickness while ensuring structural strength; heat transfer must pass through the tube wall, and thin walls can greatly shorten the heat conduction path. Heat is transferred from the fluid on one side through the tube wall to the fluid on the other side. Appropriate wall thickness reduces thermal resistance, allowing heat to be conducted between cold and hot fluids faster, thereby increasing the heat exchange rate and allowing the heat exchanger to complete more heat exchange per unit time.

[0022] Furthermore, the baffle and the partition together enclose an independent buffer confluence cavity, creating a relatively stable heat exchange transition space for the fluid.

[0023] Furthermore, when the fluid flows in the pipe, the roughness of the pipe wall is the key factor in generating frictional resistance. The capillary with a smooth inner wall greatly reduces the friction between the fluid and the pipe wall. When the fluid molecules move along the smooth surface, the drag force caused by viscosity is greatly reduced, allowing the fluid to move along the capillary more easily and quickly, avoiding the flow rate reduction and energy loss caused by the rough surface, and effectively reducing the flow resistance through the capillary.

[0024] The present invention also provides a method for preparing a capillary microchannel heat exchanger with reduced flow resistance based on any of the above methods. By using one-dimensional flow resistance calculation and three-dimensional fluid simulation calculation, the operating conditions of the heat exchanger can be comprehensively and accurately analyzed, thereby obtaining the optimal parameter data of relevant components, so that the heat exchanger meets the requirements of high efficiency and low resistance from the design source; the inlet section group is first, and then the outlet section group, or vice versa. This flexibility adapts to different production line layouts and process habits, making it easy for enterprises to adjust according to their own production conditions, while ensuring that each capillary group can be accurately arranged, laying the foundation for subsequent stable operation; vacuum diffusion welding is adopted, in a vacuum environment The atoms of the components diffuse and fuse with each other to form a high-strength, high-sealing connection. For fine structures such as capillary microchannels, conventional welding is prone to leave gaps and produce stress concentration, while vacuum diffusion welding can avoid such problems, firmly connect each layer group and the capillary, ensure that the internal fluid will not leak, and maintain a stable heat exchange flow channel. The heat exchanger performance test is carried out immediately after assembly, which can timely discover potential problems in the design, assembly, and welding links, such as excessive local flow resistance and uneven heat exchange, and quickly feedback and adjust to avoid defective products from entering the market, ensuring that the finished heat exchangers can meet the predetermined performance indicators of low flow resistance and high-efficiency heat exchange. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0026] Figure 1 A schematic diagram of the structure of a stacked arrangement of a single hot layer group and a single cold layer group in a capillary microchannel heat exchanger for reducing flow resistance provided by the present invention; Figure 2 A schematic diagram of the staggered arrangement of the buffer converging cavities of each layer in the capillary microchannel heat exchanger for reducing flow resistance provided by the present invention; Figure 3 A schematic diagram of the bending angle of a single inlet capillary or a single outlet capillary in the capillary microchannel heat exchanger for reducing flow resistance provided by the present invention; Figure 4 A schematic diagram of the flow of a hot layer group and a cold layer group at a bending angle in a capillary microchannel heat exchanger with reduced flow resistance provided by the present invention.

[0027] In the figure: 10-heat layer group; 11-inlet capillary; 12-buffer confluence cavity; 13-outlet capillary; 20-Cold layer group. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] The purpose of the present invention is to provide a capillary microchannel heat exchanger with reduced flow resistance and a preparation method thereof, so as to solve the problems existing in the prior art, effectively reduce the flow resistance and improve the heat exchange efficiency.

[0030] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] Embodiment 1 This embodiment provides a capillary microchannel heat exchanger with reduced flow resistance, such as Figure 1~Figure 4 As shown, it includes a plurality of hot layer groups 10 and a plurality of cold layer groups 20; each hot layer group 10 and each cold layer group 20 are arranged in a staggered and stacked manner; each hot layer group 10 is separated from an adjacent cold layer group 20 by a partition; each cold layer group 20 and each hot layer group 10 is used for circulating a fluid medium for heat exchange; each cold layer group 20 and each hot layer group 10 includes an inlet section group, a buffer confluence cavity 12 and an outlet section group; the buffer confluence cavity 12 is located between the inlet section group and the outlet section group; The inlet section group includes a plurality of inlet capillaries 11 arranged in sequence, and the outlet end of each inlet capillary 11 is connected to the buffer confluence cavity 12; the outlet section group includes a plurality of outlet capillaries 13 arranged in sequence, and the inlet end of each outlet capillary 13 is connected to the buffer confluence cavity 12; the inlet capillaries 11 correspond to the outlet capillaries 13 one by one; the overall outer side walls of the arranged inlet capillaries 11 and the arranged outlet capillaries 13 are sprayed with a nickel-phosphorus coating.

[0032] By setting a buffer confluence cavity 12 between the inlet section group and the outlet section group, the fluid flowing out of the inlet capillary 11 is first gathered here. When the fluid is ejected from multiple small inlet capillaries 11 at high speed, it will carry a large kinetic energy and a turbulent flow velocity distribution. The buffer confluence cavity 12 plays the role of a "speed bump" and a "rectifier", which reduces the fluid speed and redistributes it evenly, and then flows smoothly into the outlet capillary 13. Compared with the traditional single flow channel layout, it can significantly reduce the resistance of subsequent flow; in the buffer confluence cavity 12, the fluids transported from different inlet capillaries 11 are fully mixed, the temperature is more uniform, and the fluids are in harmony with each other. The temperature difference of the adjacent layer group is also more fully utilized. When this uniform fluid flows into the outlet capillary 13 to exchange heat with the fluid on the other side, the heat exchange efficiency will be improved due to the more regular temperature field; the smaller gaps between the arranged inlet capillaries 11 or the outlet capillaries 13 can be filled with the sprayed nickel-phosphorus coating, leaving only a larger flow space outside the tube, reducing the resistance of the fluid flowing in the gaps outside the tube, and the surface of the nickel-phosphorus coating is smooth, so that the flow resistance of the flow channel outside the tube can also be reduced, allowing the fluid to pass more smoothly, effectively reducing the flow resistance; based on the above measures, it can effectively reduce the flow resistance and improve the heat exchange efficiency.

[0033] Among them, the relevant setting description of the buffer confluence cavity 12 is as follows: In the optional scheme of this embodiment, it is more preferred that closed baffles are respectively provided at both ends of the space between the inlet section group and the outlet section group along the direction in which each inlet capillary tube 11 or each outlet capillary tube 13 is arranged; the space between the inlet section group and the outlet section group and the two closed baffles and the corresponding partitions together enclose a buffer confluence cavity 12. The baffles and the partitions together enclose an independent buffer confluence cavity 12, creating a relatively stable heat exchange transition space for the fluid.

[0034] In the optional scheme of this embodiment, it is more preferred that Figure 1 and Figure 2 As shown, the spacing of the buffer converging cavity 12 between the outlet end of the inlet capillary 11 and the inlet end of the corresponding outlet capillary 13 is 0.1mm~3mm. The spacing is set between 0.1mm~3mm. If the spacing is too small, the converging effect cannot be achieved, and if the spacing is too large, the overall performance of the heat exchanger will be reduced. Within this spacing range, when the fluids from different inlet capillaries 11 converge in the buffer converging cavity 12, the heat exchange is more sufficient. The appropriate spacing can reduce the "dead zone" in the buffer converging cavity 12. The so-called dead zone is the area where the fluid flows slowly and hardly participates in the heat exchange. If the spacing is too large, it is easy to form a dead zone, and the fluid stagnates in it for a long time, and the heat cannot be effectively transferred; while the spacing within the limited range allows the fluid to always be in an active flow state, eliminating the dead zone and ensuring the efficiency of the entire heat exchange process.

[0035] In the optional scheme of this embodiment, it is more preferred that Figure 2 As shown, in the projection direction of the partition, the buffer confluence cavity 12 of the cold layer group 20 and the buffer confluence cavity 12 of the adjacent hot layer group 10 are arranged in a staggered manner (specifically, as shown in FIG. Figure 2 As shown, they are staggered in the flow direction). If the buffer converging cavities 12 of each layer are all concentrated in one area, force transmission welding cannot be effectively performed here during diffusion welding. By adopting a staggered arrangement, defects caused by the inability to transmit force during diffusion welding can be effectively avoided.

[0036] Specifically, the staggered arrangement is performed by cutting the straight tube lengths of the corresponding inlet capillary 11 and outlet capillary 13 in each layer differently, for example: Figure 2 As shown, the length of the straight tube section corresponding to the inlet capillary 11 of the first layer is set at 10 cm (corresponding to Figure 2 The length of the straight tube section corresponding to the inlet capillary 11 of the second layer is set to 15 cm (corresponding to Figure 2 In the middle); and so on, the buffer confluence cavity 12 of each layer is not at the same position as that of the next layer.

[0037] The relevant setting descriptions of the inlet capillary 11 and the outlet capillary 13 are as follows: In the optional scheme of this embodiment, it is more preferred that Figure 1 As shown, the inlet end of the inlet capillary 11 is bent toward the side close to the inflow of the fluid medium, and the outlet end of the outlet capillary 13 is bent toward the side close to the outflow of the fluid medium. The curved design of the inlet end of the inlet capillary 11 allows the inflowing fluid medium to enter the inlet capillary 11 more smoothly along the curved contour, and the curved outlet end of the outlet capillary 13 allows the outflowing fluid to gradually accelerate and spread to the downstream along the curved direction; the curvature of the inlet will cause the fluid to form a certain swirl or biased flow when entering the capillary. This special flow state will make the flow path of the fluid in the capillary more complicated, no longer a simple straight line, and in disguise prolong the residence time of the fluid in the capillary. The longer residence time means more opportunities for sufficient heat exchange with the tube wall, which improves the heat exchange degree of a single pass.

[0038] In the optional scheme of this embodiment, it is more preferred that the angle between the axis of the inlet end of the inlet capillary 11 and the axis of the outlet end of the inlet capillary 11 is set to the first bending angle; the angle between the axis of the outlet end of the outlet capillary 13 and the axis of the inlet end of the outlet capillary 13 is set to the second bending angle; the range of the first bending angle and the second bending angle is 0°~180°. The bending angle is the key to optimization. The bending angle is determined according to the viscosity and pressure of the medium used and through one-dimensional flow resistance calculation plus three-dimensional fluid simulation calculation. If the angle is too small, the flow state of the fluid may not be effectively changed, and the effect of reducing the flow resistance is not obvious. If the angle is too large, the fluid flow may be turbulent, and the phenomenon of generating vortex and backflow will increase the flow resistance. Therefore, from the perspective of the overall system, a collaborative optimization method of multiple bending angles is adopted to ensure the reduction of flow resistance and improve the heat exchange effect.

[0039] Specifically, when considering the effect of the bending angle on the flow resistance, we should not only pay attention to the local flow field changes at the bend, but also consider its overall impact on the entire capillary flow channel. Optimizing a local bending angle may reduce the flow resistance of the area to a certain extent, but it may have an adverse effect on the subsequent flow channel, such as causing uneven flow distribution. Therefore, it is necessary to start from the perspective of the overall system and coordinate the optimization of multiple bending angles.

[0040] In the optional scheme of this embodiment, it is more preferred that the wall thickness of the inlet capillary 11 and the outlet capillary 13 are both 0.1mm~0.5mm. The setting of the wall thickness range can ensure the structural strength while reducing the additional flow resistance caused by the wall thickness as much as possible; heat transfer must pass through the tube wall, and thin walls can greatly shorten the heat conduction path. Heat is transferred from one side of the fluid to the other side through the tube wall. Appropriate wall thickness reduces thermal resistance, allowing heat to be conducted faster between cold and hot fluids, improving the heat exchange rate, and allowing the heat exchanger to complete more heat exchange per unit time.

[0041] In the optional scheme of this embodiment, it is more preferred that the inner walls of the inlet capillary 11 and the outlet capillary 13 are smooth. When the fluid flows in the pipeline, the roughness of the tube wall is the key factor in generating friction resistance. The capillary with a smooth inner wall greatly reduces the friction between the fluid and the tube wall. When the fluid molecules move along the smooth surface, the drag force caused by the viscosity is greatly reduced, so that the fluid can move along the capillary more easily and quickly, avoiding the flow rate reduction and energy loss caused by the rough surface, and effectively reducing the flow resistance through the capillary.

[0042] Among them, about other related settings description: In the optional scheme of this embodiment, it is more preferred that the flow form of the fluid medium in the hot layer group 10 and the fluid medium in the adjacent cold layer group 20 is countercurrent or crossflow. In the countercurrent state, the flow directions of the hot fluid and the cold fluid are completely opposite. The temperature of the hot fluid is the highest when it just enters the heat exchanger, and the temperature of the cold fluid it meets is the lowest at this time. The temperature difference between the two is extremely large, which provides a strong driving force for heat transfer; as the heat exchange process progresses, the temperature of the hot fluid gradually decreases, and the temperature of the cold fluid gradually increases, but the temperature difference throughout the process can always be maintained at a relatively considerable level. This continuous and strong temperature difference utilization enables the countercurrent heat exchanger to obtain more heat exchange than other flow forms under the same heat exchange area, fluid flow rate and inlet and outlet temperature conditions, and the heat exchange efficiency is significantly improved; when the crossflow occurs, the flow directions of the hot and cold fluids are perpendicular to each other. This layout makes the overall structural design of the heat exchanger more diverse and flexible. Engineers can easily adjust the direction and arrangement of the hot and cold fluid channels according to the shape and size of the actual installation space to adapt to the compact and special-shaped installation requirements of different equipment; the flow form can be selected according to actual conditions.

[0043] Embodiment 2 This embodiment provides a method for preparing a capillary microchannel heat exchanger with reduced flow resistance based on the first embodiment, comprising the following steps: S1, the optimal flow form of the heat exchanger, the number of layers of the hot layer group 10 and the cold layer group 20, the wall thickness of each inlet capillary 11 and each outlet capillary 13 and their optimal bending angles, and the corresponding size data of the buffer converging cavity 12 (i.e., the distance between the outlet end of the inlet capillary 11 and the inlet end of the outlet capillary 13) are obtained through one-dimensional flow resistance calculation and three-dimensional fluid simulation calculation; Among them, a capillary with a wall thickness of 0.1 mm to 0.5 mm is selected for bending, and the bending force of the bending process is 100 N to 500 N. By accurately controlling the bending force, the capillary is bent according to a predetermined shape to form a corresponding inlet capillary 11 and an outlet capillary 13; S2, assembling the inlet section group and the outlet section group in each layer in sequence; wherein, firstly, the inlet capillaries 11 of the inlet section group are arranged neatly according to the required number, and the corresponding nickel-phosphorus coating is sprayed on the outer side wall thereof as a whole, and then, according to the corresponding size of the buffer confluence cavity 12 obtained in S1, the outlet capillaries 13 of the outlet section group are arranged neatly according to the required number, and the corresponding nickel-phosphorus coating is sprayed on the outer side wall thereof as a whole (the multiple capillaries after spraying are more tightly packed, forming a single-row whole, rather than a whole formed by a single tube arranged in sequence); or, after the outlet section group is prepared first, the corresponding nickel-phosphorus coating is sprayed on the outer side wall thereof as a whole, and according to the corresponding size of the buffer confluence cavity 12 obtained in S1, the inlet section group is prepared, and the corresponding nickel-phosphorus coating is sprayed on the outer side wall thereof; S3, laying the next adjacent hot layer group 10 or cold layer group 20 according to the optimal flow form obtained in S1; S4, after assembling to the required number of layers, the whole is subjected to vacuum diffusion welding, and the corresponding pressure test and other heat exchanger performance tests are carried out, and the inlet and outlet headers, pipes, etc. are welded by argon arc welding or electric arc welding.

[0044] By using one-dimensional flow resistance calculation and three-dimensional fluid simulation calculation, the operating conditions of the heat exchanger can be comprehensively and accurately analyzed, so as to obtain the best parameter data of relevant components, so that the heat exchanger can meet the needs of high efficiency and low resistance from the design source; the inlet section group is first, then the outlet section group, or vice versa. This flexibility adapts to different production line layouts and process habits, which is convenient for enterprises to adjust according to their own production conditions, and at the same time ensures that each capillary group can be accurately arranged, laying the foundation for subsequent stable operation; vacuum diffusion welding is adopted. In a vacuum environment, the atoms of the components diffuse and fuse with each other to form a high-strength and high-sealing connection. For fine structures such as capillary microchannels, conventional welding is prone to leave gaps and produce stress concentration, while vacuum diffusion welding can avoid such problems, firmly connect each layer group and capillary, ensure that the internal fluid will not leak, and maintain a stable heat exchange flow channel. After assembly, the heat exchanger performance test is carried out immediately, which can timely discover potential problems in the design, assembly, and welding links, such as excessive local flow resistance and uneven heat exchange, and quickly feedback and adjust to avoid defective products from entering the market, ensuring that the finished heat exchanger can meet the predetermined performance indicators of low flow resistance and efficient heat exchange.

[0045] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A capillary microchannel heat exchanger with reduced flow resistance, characterized in that: It comprises a plurality of hot layer groups and a plurality of cold layer groups; each of the hot layer groups and each of the cold layer groups are arranged in a staggered and stacked manner; each of the hot layer groups and the adjacent cold layer groups are separated by a partition; each of the cold layer groups and each of the hot layer groups has a fluid medium for circulating heat exchange; The cold layer group and the hot layer group both include an inlet section group, a buffer confluence cavity and an outlet section group; the buffer confluence cavity is located between the inlet section group and the outlet section group; the inlet section group includes a plurality of inlet capillaries arranged in sequence, and the outlet end of each inlet capillary is connected to the buffer confluence cavity; the outlet section group includes a plurality of outlet capillaries arranged in sequence, and the inlet end of each outlet capillary is connected to the buffer confluence cavity; the inlet capillaries correspond to the outlet capillaries one by one; The entire outer side walls of the arranged inlet capillaries and the arranged outlet capillaries are sprayed with a nickel-phosphorus coating.

2. The capillary microchannel heat exchanger with reduced flow resistance according to claim 1, characterized in that: The distance between the outlet end of the inlet capillary and the inlet end of the corresponding outlet capillary of the buffer confluence cavity is 0.1 mm to 3 mm.

3. The capillary microchannel heat exchanger with reduced flow resistance according to claim 1, characterized in that: The inlet end of the inlet capillary is bent toward a side close to the inflow of the fluid medium, and the outlet end of the outlet capillary is bent toward a side close to the outflow of the fluid medium.

4. The capillary microchannel heat exchanger with reduced flow resistance according to claim 1, characterized in that: In the projection direction of the partition, the buffer confluence cavity of the cold layer group and the buffer confluence cavity of the adjacent hot layer group are arranged in a staggered manner.

5. The capillary microchannel heat exchanger with reduced flow resistance according to claim 3, characterized in that: The angle between the axis of the inlet end of the inlet capillary and the axis of the outlet end of the inlet capillary is set as a first bending angle; the angle between the axis of the outlet end of the outlet capillary and the axis of the inlet end of the outlet capillary is set as a second bending angle; The first bending angle and the second bending angle range from 0° to 180°.

6. The capillary microchannel heat exchanger with reduced flow resistance according to claim 1, characterized in that: The flow form of the fluid medium in the hot layer group and the fluid medium in the adjacent cold layer group is countercurrent or crossflow.

7. The capillary microchannel heat exchanger with reduced flow resistance according to claim 1, characterized in that: The wall thickness of the inlet capillary and the outlet capillary are both 0.1 mm to 0.5 mm.

8. The capillary microchannel heat exchanger with reduced flow resistance according to claim 1, characterized in that: Along the arrangement direction of each of the inlet capillaries or each of the outlet capillaries, closed baffles are respectively provided at both ends of the space between the inlet section group and the outlet section group; The space between the inlet section group and the outlet section group, the two closed baffles and the corresponding partitions together enclose the buffer confluence cavity.

9. The capillary microchannel heat exchanger with reduced flow resistance according to claim 1, characterized in that: The inner walls of the inlet capillary and the outlet capillary are smooth.

10. A method for preparing a capillary microchannel heat exchanger with reduced flow resistance according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1, obtaining the optimal flow form of the heat exchanger, the number of layers of the hot layer group and the cold layer group, the wall thickness of each inlet capillary and each outlet capillary, and the corresponding size data of the buffer confluence cavity through one-dimensional flow resistance calculation and three-dimensional fluid simulation calculation; S2, assembling the inlet section group and the outlet section group in each layer in turn by layer; wherein, firstly arranging the inlet capillaries of the inlet section group in accordance with the required number, spraying the corresponding nickel-phosphorus coating on the outer side wall thereof as a whole, and then arranging the outlet capillaries of the outlet section group in accordance with the required number, spraying the corresponding nickel-phosphorus coating on the outer side wall thereof as a whole according to the corresponding size of the buffer confluence cavity obtained in S1; or, firstly preparing the outlet section group, spraying the corresponding nickel-phosphorus coating on the outer side wall thereof as a whole, and then preparing the inlet section group according to the corresponding size of the buffer confluence cavity obtained in S1, and spraying the corresponding nickel-phosphorus coating on the outer side wall thereof; S3, laying the hot layer group or the cold layer group of the next adjacent layer according to the optimal flow form obtained in S1; S4, after assembling to the required number of layers, the whole is vacuum diffusion welded and the heat exchanger performance test is performed.

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