Micro-channel heat exchanger with shark scale imitating structure and manufacturing method of micro-channel heat exchanger

Abstract

The invention relates to the technical field of micro-channel heat dissipation, and discloses a micro-channel heat exchanger with a shark scale imitating structure and a manufacturing method of the micro-channel heat exchanger. The heat exchanger comprises a micro-channel base body, a plurality of parallel V-shaped grooves are formed in the surface of the micro-channel base body, the length direction of the V-shaped grooves is parallel to the flowing direction of a working medium, and fan-shaped scale structures are distributed on the inclined faces of the V-shaped grooves in an array mode. The tip end of the scale structure is opposite to the flowing direction of the working medium, a plurality of grooves are formed in the upper surface of the scale structure, and the sectional areas of the grooves and the convex ridges between the grooves are gradually increased in the flowing direction of the working medium. According to the micro-channel base body, through the shark scale imitating structure, the heat exchange effect is enhanced, meanwhile, the flowing resistance of a cooling working medium is reduced or not remarkably increased, and the energy consumption needed for driving the working medium to flow is reduced while the heat exchange efficiency is guaranteed. The micro-channel base body in the micro-channel heat exchanger is manufactured through the selective laser melting 3D printing technology, and integrated forming of the micro-channel base body can be efficiently achieved.

Description

Technical Field

[0001] The invention relates to the technical field of microchannel heat dissipation, and in particular to a microchannel heat exchanger with a shark scale-like structure and a manufacturing method thereof. Background Art

[0002] At present, electronic components are developing towards integration, high frequency and complex functions. As their characteristic size decreases, their heat flux increases sharply. Exploring more efficient heat dissipation means is one of the main technical issues to further improve the performance of integrated electronic components. Microchannel heat exchangers are considered to be an ideal way to solve the high heat flux density of micro components due to their light weight, small size and good heat dissipation performance. Traditional microchannel heat exchangers process rectangular, triangular, trapezoidal and other microchannel array structures with smooth walls on metal or silicon substrates, which have problems such as small heat exchange area, limited heat transfer performance and low critical heat flux. For this reason, some researchers have proposed to set microstructures such as turbulent microcolumns, porous coatings and concave structures on the walls of microchannels. It can significantly increase the heat exchange area, destroy the normal development of the boundary layer, increase the boiling phase change core, and thus enhance heat transfer. However, these enhanced structures will significantly increase the flow pressure drop and resistance, thereby increasing the pump work, causing energy waste and bringing adverse effects. Therefore, it is urgent to design a new microchannel structure that can reduce flow resistance while enhancing heat transfer. Summary of the invention

[0003] In order to overcome the shortcomings of the prior art, the purpose of the present invention is to provide a microchannel heat exchanger with a shark scale-like structure, which can increase the heat exchange area and destroy the continuous development of the boundary layer while avoiding a significant increase in the flow resistance of the working fluid and reducing the energy consumption required to drive the fluid.

[0004] To solve the above problems, the technical solution adopted by the present invention is as follows: a microchannel heat exchanger with a shark scale-like structure, comprising a microchannel substrate, a surface of the microchannel substrate is provided with a plurality of parallel V-shaped grooves, the length direction of the V-shaped grooves is parallel to the flow direction of the working medium, fan-shaped scale structures are arrayed on the inclined surface of the V-shaped grooves, the tip of the scale structure is facing away from the flow direction of the working medium, the upper surface of the scale structure is at a certain inclination angle with the inclined surface of the V-shaped groove along the flow direction of the working medium, a plurality of grooves are arranged on the upper surface of the scale structure, the cross-section of the grooves is fan-shaped, the cross-sectional area of ​​the grooves and the ridges between the grooves gradually increases along the flow direction of the working medium, the width and depth of the grooves gradually increase along the flow direction of the working medium, the height of the ridges gradually increases along the flow direction of the working medium, and the grooves and the ridges are both composed of smooth curved surfaces.

[0005] In the above-mentioned microchannel substrate, the cross section of the V-shaped groove is an isosceles triangle, the depth-to-width ratio of the V-shaped groove is in the range of 1:1-2:1, and the angle of the slope of the V-shaped groove is greater than or equal to 60°.

[0006] In the above-mentioned microchannel substrate, the dimensionless height and dimensionless spacing of the V-shaped grooves are both less than or equal to 30.

[0007] In the above-mentioned microchannel substrate, the hydraulic diameter of the V-shaped groove is in the range of 0.5-1 mm.

[0008] In the above-mentioned microchannel substrate, the inclination angle between the upper surface of the scale structure and the inclined surface of the V-shaped groove ranges from 20° to 45°.

[0009] In the above-mentioned microchannel substrate, the characteristic size of the grooves ranges from 30 to 80 um, and the characteristic size of the ridges ranges from 20 to 60 um.

[0010] A method for manufacturing the above-mentioned microchannel substrate comprises the following steps:

[0011] 1) Design a three-dimensional model of the microchannel matrix;

[0012] 2) Import the 3D model into the laser selective melting slicing software and adjust the model to the optimal printing position;

[0013] 3) Select metal powder, use laser selective melting 3D printing equipment to perform powder printing layer by layer, and print a microchannel matrix with a shark scale-like structure according to the three-dimensional model;

[0014] 4) taking out the microchannel base and performing ultrasonic cleaning;

[0015] 5) The microchannel substrate with the shark scale-like structure is welded and packaged with the upper cover plate and the lower cover plate, and connected with external pipelines and pumps to form a circulation loop to obtain a complete microchannel heat exchanger.

[0016] In the above-mentioned method for manufacturing a microchannel heat exchanger, the laser power range of the laser selective melting 3D printing device for printing the microchannel matrix is ​​100-200W.

[0017] In the above-mentioned method for manufacturing a microchannel heat exchanger, the printing speed of the microchannel substrate printed by the laser selective melting 3D printing device is in the range of 50-100 mm / s, the slice thickness is 20-40 um, and the path distance is in the range of 0.01-0.05 mm.

[0018] In the above-mentioned method for manufacturing a microchannel heat exchanger, the particle size of the metal powder is in the range of 10-30 um.

[0019] Compared with the prior art, the present invention has the following significant advantages:

[0020] 1) The microchannel structure can significantly increase the heat exchange area of ​​the microchannel by arranging a shark scale-like structure on the inclined surface of the V-shaped groove, destroy the normal development of the boundary layer, promote turbulence, and thus enhance heat transfer.

[0021] 2) A scale structure with bionic shark scale micro-texture is arranged on the inclined surface of the V-shaped groove. The sloped ridge and fan-shaped groove structure of the bionic shark scale micro-texture are utilized to generate a low-speed secondary vortex at the rear end of the texture, thereby reducing the momentum exchange in the flow boundary layer and the viscous resistance near the wall, thereby reducing the pump work and the energy consumed to drive the cooling medium.

[0022] 3) The use of laser selective melting technology can achieve efficient integrated forming of microchannels and their wall shark scale-like structures, giving full play to the advantages of laser selective melting in rapid forming and being suitable for processing complex three-dimensional structures, while achieving integrated forming of tiny channels and millimeter-level microtextures.

[0023] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the three-dimensional structure of a microchannel heat exchanger according to an embodiment of the present invention;

[0025] Figure 2 A schematic diagram of the three-dimensional structure of a microchannel substrate according to an embodiment of the present invention;

[0026] Figure 3 A front view of a microchannel matrix structure according to an embodiment of the present invention;

[0027] Figure 4 A schematic diagram of the three-dimensional structure of a scale structure according to an embodiment of the present invention;

[0028] Figure 5 A top view of a scale structure according to an embodiment of the present invention;

[0029] Figure 6 A front view of a scale structure according to an embodiment of the present invention;

[0030] Figure 7 A side view of a scale structure according to an embodiment of the present invention;

[0031] Figure 8 The present invention is a flowchart of a method for manufacturing a microchannel substrate according to an embodiment of the present invention.

[0032] Description of Figure Numbers:

[0033] 100 microchannel substrate, 110 V-shaped groove, 120 scale structure, 121 groove, 122 ridge, 200 lower cover plate, 300 upper cover plate. DETAILED DESCRIPTION

[0034] The embodiments of the present invention are described in detail below. Figures 1 to 7 An embodiment of the present invention provides a microchannel heat exchanger with an anti-shark scale structure, including an upper cover plate 300, a lower cover plate 200 and a cavity formed by the upper cover plate 300 and the lower cover plate 200, wherein both ends of the cavity are provided with an outlet and an inlet for the cooling medium to enter and exit. The surface of the microchannel substrate 100 is provided with a plurality of parallel V-shaped grooves 110, and the direction of the V-shaped grooves 110 is parallel to the flow direction of the cooling medium. Fan-shaped scale structures 120 are arranged in an array on the inclined surface of the V-shaped grooves 110, and the tip of the scale structure 120 faces away from the flow direction of the medium. Figures 4 to 7 The upper surface of the scale structure 120 has a certain inclination angle with the inclined surface of the V-shaped groove 110 along the working medium flow direction. A plurality of grooves 121 with fan-shaped cross sections are arranged on the upper surface of the scale structure 120. The cross-sectional areas of the grooves 121 and the ridges 122 between the grooves 121 gradually increase along the working medium flow direction. The width and depth of the grooves 121 gradually increase along the working medium flow direction, and the height of the ridges 122 gradually increases along the working medium flow direction. The grooves 121 and the ridges 122 are both composed of smooth curved surfaces.

[0035] The microchannel substrate 100 of the embodiment of the present invention, by arranging the scale structure 120 in an array on the inclined surface of the V-shaped groove 110, and arranging the groove 121 on the scale structure 120 to imitate the micro texture of the scales on the surface of shark skin, by simplifying the overlapping scales that imitate the "cortical scale convexity" on the surface of shark skin to improve the drag reduction rate, and reduce the resistance of the cooling medium flowing through the microchannel substrate 100. The cross-sectional areas of the ridges 122 and the grooves 121 on the scale structure 120 gradually increase along the flow direction of the medium, so that the height of the grooves 121 and the ridges 122 gradually increases along the flow direction of the medium, and the width gradually widens, which is conducive to the smooth flow of the medium fluid along the flow direction. There is a height difference between the V-shaped groove 110 and the scale structure 120. This height difference makes the medium preferentially converge at the trough position of the grooves 121 of the V-shaped groove 110 and the scale structure 120, thereby effectively limiting the lateral flow of the medium and reducing the intensity of turbulence. The working fluid flows into the microchannel and is diverted into multiple flow paths by the array of scale structures 120, which can effectively break the thermal boundary layer and improve the heat exchange efficiency. At the same time, due to the height difference between the longitudinal protrusion height and the lateral protrusion height, the working fluid moves along the ridge 122, and rarely moves horizontally, so that the fluid in the groove 121 of the scale structure 120 is dominated by the viscous force, so that the flow of this part of the fluid is blocked, and the thickness of the viscous bottom layer is increased, which can effectively reduce the average velocity gradient on the wall. The ridge 122 and groove 121 structure can effectively limit the water flow in the groove 121, thereby greatly reducing the resistance of the fluid. The microchannel matrix 100 can reduce the flow resistance of the cooling working fluid while improving the heat exchange efficiency, thereby reducing the energy required to pump the working fluid flow and reducing the energy consumption required by the heat exchanger.

[0036] Moreover, the surfaces of the groove 121 and the ridge 122 of the microchannel substrate 100 are both composed of smooth curved surfaces, so that the cross-sections of the groove 121 and the ridge 122 are both fan-shaped. According to the second vortex theory, the inclined ridge 122 and the vortex can generate secondary vortex in the fan-shaped groove 121, and the secondary vortex allows the low-speed fluid to be retained in the groove 121, limiting the concentration of low-momentum fluid; in addition, the secondary vortex can play the role of a "rolling bearing", changing the friction between the fluid and the wall from sliding friction to rolling friction, further reducing the flow resistance.

[0037] It is understandable that the V-shaped groove 110 preferably adopts a symmetrical structure. In this embodiment, the cross section of the V-shaped groove 110 is an isosceles triangle, and the scale structure 120 is symmetrically arranged on the inclined surfaces on both sides of the V-shaped groove 110 with the symmetry plane of the V-shaped groove 110. Three rows of scale structures 120 are arranged in an array on each inclined surface. The depth-to-width ratio of the V-shaped groove 110 is preferably in the range of 1:1-2:1, the angle of the inclined surface is greater than or equal to 60°, and the dimensionless height and dimensionless spacing of the V-shaped groove 110 are both less than or equal to 30. If this range is exceeded, a resistance increase effect will occur. The hydraulic diameter of the V-shaped groove 110 is in the range of 0.5-1mm.

[0038] Reference Figures 3 to 6 In this embodiment, two grooves 121 and three ridges 122 are arranged on the upper surface of each scale structure 120. The three ridges 122 and the two grooves 121 are radially arranged on the upper surface of the scale structure 120 with the center of the circle of the scale structure 120 as the radial center, and the angle intervals of the three ridges 122 are equal. The inclination angle between the upper surface of the scale structure 120 and the inclined surface of the V-shaped groove 110 is preferably in the range of 20°-45°, the characteristic size of the groove 121 is preferably in the range of 30-80um, and the characteristic size of the ridge 122 is preferably in the range of 20-60um.

[0039] In order to reduce the manufacturing cost of the microchannel substrate 100, refer to Figure 7 The microchannel substrate 100 of the embodiment of the present invention is made by a 3D printing process of laser selective melting, which is a main technical approach in metal material additive manufacturing and is suitable for the molding of metal micro-weavings with complex shapes. The microchannel substrate 100 of the embodiment of the present invention can be integrally formed, and the post-processing process only requires one-time wire cutting and cleaning and drying. The manufacturing process is simple and the processing cost is low. The specific steps include:

[0040] 1) Designing a three-dimensional model of the microchannel substrate 100. In this embodiment, the three-dimensional model of the microchannel substrate 100 is established using Solidworks software, and after the establishment is completed, the model is saved in STL format;

[0041] 2) Import the 3D model in STL format into the laser melting and slicing software Magics, and use the software commands to adjust the model to the optimal printing position so that the matrix and the molding substrate are in good contact;

[0042] 3) Select metal powder, set the printing parameters of the laser selective melting 3D printing device, use the laser selective melting 3D printing device to perform powder printing layer by layer, and print out a microchannel matrix 100 with a shark scale-like structure according to the three-dimensional model. In this embodiment, the particle size range of the metal powder is preferably 10-30um, the laser power range is preferably 100-200W, the printing speed range is preferably 50-100mm / s, the slice thickness is preferably 20um, the filling pattern type is preferably set to no pattern, and the path distance range is preferably 0.01-0.05mm; before starting printing, clean the molding chamber and wipe the laser lens with alcohol, align the knife and place the printing substrate reasonably, add metal powder to the equipment, open the nitrogen bottle to inject safety gas into the equipment, and start printing when the safety gas content reaches the target value. The equipment automatically performs powder printing layer by layer;

[0043] 4) taking out the microchannel substrate 100 and performing ultrasonic cleaning; after printing, cutting the printed microchannel substrate 100 from the molding substrate by wire cutting, then putting the microchannel substrate 100 into a sealed bag filled with alcohol, and then putting the sealed bag into an ultrasonic cleaning machine for cleaning for 5 minutes. After cleaning, taking out the sample of the microchannel substrate 100 with tweezers, and drying the sample with a hair dryer;

[0044] 5) The microchannel substrate 100 with the shark-proof structure is welded and packaged with the upper cover plate 300 and the lower cover plate 200, and connected with external pipelines and pumps to form a circulation loop to obtain a complete microchannel heat exchanger.

[0045] It should be noted that in the description of the present invention, if there are any orientation descriptions, such as up, down, front, back, left, right, etc., the orientations or positional relationships indicated are all based on the orientations or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed or operated in a specific orientation, and cannot be understood as a limitation on the present invention.

[0046] In the description of the present invention, "several" means one or more, "more" means two or more, "greater than", "less than", "exceed" etc. are understood to exclude the number itself, and "above", "below", "within" etc. are understood to include the number itself. If there is a description of "first" or "second", it is only used to distinguish the technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0047] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0048] The above-mentioned embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and substitutions made by technicians in this field on the basis of the present invention shall fall within the scope of protection required by the present invention.

Claims

1. A microchannel heat exchanger with a shark scale-like structure, characterized in that: The invention comprises a microchannel substrate (100), wherein a plurality of parallel V-shaped grooves (110) are provided on the surface of the microchannel substrate (100), wherein the length direction of the V-shaped grooves (110) is parallel to the flow direction of the working medium, and fan-shaped scale structures (120) are arranged in an array on the inclined surface of the V-shaped grooves (110), wherein the tip of the scale structure (120) faces away from the flow direction of the working medium, and the upper surface of the scale structure (120) forms a certain inclination angle with the inclined surface of the V-shaped groove (110) along the flow direction of the working medium, A plurality of grooves (121) are arranged on the upper surface of the scale structure (120); the cross section of the grooves (121) is fan-shaped; the cross-sectional areas of the grooves (121) and the ridges (122) between the grooves (121) gradually increase along the flow direction of the working medium; the width and depth of the grooves (121) gradually increase along the flow direction of the working medium; the height of the ridges (122) gradually increases along the flow direction of the working medium; and the grooves (121) and the ridges (122) are both composed of smooth curved surfaces.

2. The microchannel heat exchanger according to claim 1, characterized in that: The cross section of the V-shaped groove (110) is an isosceles triangle, the depth-to-width ratio of the V-shaped groove (110) is in the range of 1:1-2:1, and the angle of the inclined surface of the V-shaped groove (110) is greater than or equal to 60°.

3. The microchannel heat exchanger according to claim 1, characterized in that: The hydraulic diameter of the V-shaped groove (110) is in the range of 0.5-1 mm.

4. The microchannel heat exchanger according to claim 1, characterized in that: The inclination angle between the upper surface of the scale structure (120) and the inclined surface of the V-shaped groove (110) is in the range of 20°-45°.

5. The microchannel heat exchanger according to claim 1, characterized in that: The characteristic size of the groove (121) ranges from 30 to 80 um, and the characteristic size of the ridge (122) ranges from 20 to 60 um.

6. A method for manufacturing a microchannel heat exchanger according to any one of claims 1 to 5, comprising the following steps: 1) designing a three-dimensional model of a microchannel substrate (100); 2) Import the 3D model into the laser selective melting slicing software and adjust the model to the optimal printing position; 3) Selecting metal powder, using a laser selective melting 3D printing device to perform powder printing layer by layer, and printing a microchannel matrix (100) having a shark scale-like structure according to the three-dimensional model; 4) taking out the microchannel base and performing ultrasonic cleaning; 5) The microchannel substrate (100) having the shark scale-like structure is welded and packaged with the upper cover plate (300) and the lower cover plate (200), and connected with external pipelines and pumps to form a circulation loop, thereby obtaining a complete microchannel heat exchanger.

7. The method for manufacturing a microchannel heat exchanger according to claim 6, characterized in that: The laser power range of the laser selective melting 3D printing device for printing the microchannel matrix (100) is 100-200W.

8. The method for manufacturing a microchannel heat exchanger according to claim 6, characterized in that: The laser selective melting 3D printing device prints the microchannel matrix (100) at a printing speed ranging from 50 to 100 mm / s, a slice thickness of 20 to 40 um, and a path distance ranging from 0.01 to 0.05 mm.

9. The method for manufacturing a microchannel heat exchanger according to claim 6, characterized in that: The particle size of the metal powder is in the range of 10-30 um.

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