A multi-scale sunken groove microchannel heat exchanger and a manufacturing method thereof

Abstract

The present invention discloses a multi-scale recessed microchannel heat exchanger with a rough texture structure and a manufacturing method thereof. The microchannel heat exchanger includes a cover plate and a metal microchannel substrate bonded together from top to bottom. The metal microchannel substrate is provided with a plurality of recessed microchannels, and the microchannel wall is provided with a rough texture structure to enhance disturbance, destroy the boundary layer, and increase the surface roughness and heat exchange area, so as to provide sufficient vaporization cores for bubble nucleation, thereby significantly enhancing the heat transfer performance of the microchannel heat exchanger. During preparation, a plurality of rectangular slits are firstly processed on the metal microchannel substrate by a multi-blade micro-tooth flat-bottom micro-milling cutter, and then a recessed cavity is processed along the center line of the rectangular slit by a multi-blade micro-tooth ball-head micro-milling cutter, and a rough texture structure is generated on the microchannel wall at the same time. The present invention has a simple manufacturing process and low processing cost, and can realize the high-efficiency and low-cost preparation and forming of the enhanced heat transfer structure in the multi-scale microchannel.

Description

Technical Field

[0001] The present invention relates to the field of heat exchangers, and more specifically to a multi-scale recessed groove microchannel heat exchanger and a manufacturing method thereof. Background Art

[0002] With the continuous high integration of electronic devices, the number of unit devices per unit area and the number of functional modules within the devices have increased significantly. Inevitably, extremely high heat is generated in a narrow space, causing the internal heat flux density of the devices to rise rapidly, seriously affecting their performance. Microchannel heat exchangers have the advantages of small volume, compact structure, high heat transfer efficiency, etc., and are an ideal choice for solving the heat dissipation problem of high heat flux density devices.

[0003] Currently, most microchannel radiators use microchannels with rectangular, V-shaped, or trapezoidal cross-sections in the transverse direction, and the channel walls are smooth. They have problems such as a relatively small heat transfer area, a large superheat at the onset of nucleate boiling, a low critical heat flux density, obvious temperature and pressure fluctuations, and unstable boiling. The recessed groove microchannel uses a semi-closed recessed structure, and the transition structure between the top slit and the bottom large cavity can be used to disrupt the normal development of the flow and heat transfer boundary layers, promoting single-phase convective heat transfer. Its bottom circular cavity and top rectangular slit structure can capture gas during the boiling nucleation process to form a steam trap, becoming a stable boiling activation point, thereby forming a stable vaporization core, promoting boiling nucleation, significantly reducing the superheat at the onset of boiling, and suppressing the instability of two-phase flow, improving the boiling heat transfer performance, and thus significantly strengthening heat transfer. However, the wall surface of the traditional single-scale recessed groove microchannel is a smooth surface, and the heat transfer area still needs to be improved, and the heat transfer effect can still be further strengthened. Summary of the Invention

[0004] The purpose of the present invention is to provide a multi-scale recessed groove microchannel heat exchanger and a manufacturing method thereof, which can increase the surface roughness and heat transfer area, provide sufficient vaporization cores for bubble nucleation, strengthen heat transfer, and have a simple manufacturing process, low processing cost, and high processing efficiency, overcoming the deficiencies of the existing microchannel heat exchangers.

[0005] The purpose of the present invention is achieved through the following technical solutions:

[0006] A multi-scale recessed groove microchannel heat exchanger includes a metal microchannel substrate and a cover plate attached to the metal microchannel substrate. A cooling working fluid inlet is provided on one side of the cover plate, and a cooling working fluid outlet is provided on the other side of the cover plate. A plurality of microchannels are provided on the metal microchannel substrate, and the microchannels are used to connect the cooling working fluid inlet and the cooling working fluid outlet. The microchannels are recessed groove structures with rough textures on the wall surfaces;

[0007] The recessed groove is composed of a rectangular slit and a recessed cavity;

[0008] The cross section of the rough texture is triangular or trapezoidal;

[0009] The plurality of microchannels are equidistant and parallel to each other;

[0010] An inlet reservoir and an outlet reservoir are respectively arranged on both sides of the metal microchannel substrate, the inlet reservoir and the outlet reservoir are respectively connected to the cooling medium inlet and the cooling medium outlet, and a plurality of microchannels are connected between the inlet reservoir and the outlet reservoir.

[0011] A method for manufacturing a multi-scale sunken groove microchannel heat exchanger, the method comprising the following steps:

[0012] Step 1: Prepare a multi-blade micro-tooth flat-bottom micro-milling cutter and a multi-blade micro-tooth ball-end micro-milling cutter, wherein the multi-blade micro-tooth flat-bottom micro-milling cutter and the multi-blade micro-tooth ball-end micro-milling cutter both have multiple cutting edges, and the cutting edges are discretely formed into micro-tooth structures; the cutting edge length of the flat-bottom micro-milling cutter is 0.3mm-1.0mm, and the tool diameter is 0.3mm-0.6mm; the multi-blade micro-tooth ball-end micro-milling cutter is preferably a multi-blade micro-tooth ball-end micro-milling cutter, and the tool head diameter of the multi-blade micro-tooth ball-end micro-milling cutter is 0.6mm-1.0mm, and the core diameter is 0.4mm-0.8mm; the speed of the multi-blade micro-tooth flat-bottom micro-milling cutter is 10000r / min-15000r / min, the feed speed is 60mm / min-120mm / min, and the back cutting amount is 0.1mm-0.5mm; the speed of the multi-blade micro-tooth ball-end micro-milling cutter is 10000r / min-15000r / min, the feed speed is 30mm / min-60mm / min, and the back cutting amount is 1.0mm-1.2mm;

[0013] Step 2: Select the first metal plate and the second metal plate as the cover plate and the metal microchannel substrate;

[0014] Step 3: Use a multi-blade micro-tooth flat-bottom micro-milling cutter to process the second metal plate to form multiple rectangular slits;

[0015] Step 4: A multi-blade micro-tooth ball-end micro-milling cutter is used to process the second metal plate along the center line of the rectangular slit to form a concave cavity, and the processed metal plate is ultrasonically cleaned and taken out for drying to obtain a cover plate and a microchannel substrate, wherein the rectangular slit and the concave cavity are both provided with a rough texture structure;

[0016] Step 5: Fix the cover plate and the metal microchannel substrate and connect them with the external pipe and water pump to form a whole, forming a forced circulation loop to obtain a complete microchannel heat exchanger;

[0017] The beneficial effects of the present invention are:

[0018] ​1. The multi-scale reentrant groove microchannel not only has the advantages of the reentrant microchannel structure in promoting boiling nucleation and enhancing boiling heat transfer, but also the rough texture structure on the wall can significantly increase the surface roughness and heat transfer area, strengthen fluid disturbance, disrupt the normal development of the boundary layer, provide sufficient vaporization nuclei for bubble nucleation, and has a good effect on enhancing heat transfer.

[0019] 2. By using a multi-edge micro-tooth flat-bottom and ball-end micro-milling cutter, while machining rectangular slits and sunken cavities, the integrated forming of the rough texture structure on the wall can be realized without secondary processing technology, thus significantly improving the processing efficiency of the multi-scale microchannel.

[0020] 3. Using the micro-milling processing method, the manufacturing process is simple, the processing cost is low, and the processing accuracy is high. It can realize the high-efficiency and low-cost preparation and forming of the enhanced heat transfer structure in the multi-scale microchannel. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention will be further described in detail below with reference to the drawings and specific implementation methods.

[0022] Figure 1 is a schematic structural diagram of the microchannel heat exchanger of the present invention;

[0023] Figure 2 is a schematic structural diagram of the process of machining the microchannel substrate using a multi-edge micro-tooth flat-bottom micro-milling cutter of the present invention;

[0024] Figure 3 is a schematic structural diagram of the process of machining the microchannel substrate using a multi-edge micro-tooth ball-end micro-milling cutter of the present invention;

[0025] Figure 4 is a schematic structural diagram of the multi-edge micro-tooth flat-bottom micro-milling cutter of the present invention;

[0026] Figure 5 is a schematic structural diagram of the multi-edge micro-tooth ball-end micro-milling cutter of the present invention;

[0027] Figure 6 is a schematic cross-sectional structure diagram of the rectangular slit at the top of the microchannel of the present invention;

[0028] Figure 7 is a schematic cross-sectional structure diagram of the microchannel of the present invention;

[0029] In the figure:

[0030] Cover plate 1; Cooling working fluid inlet 11; Cooling working fluid outlet 12;

[0031] Metal microchannel substrate 2; Inlet liquid storage tank 21; Outlet liquid storage tank 22; Microchannel 23; Rectangular slit 231; Circular cavity 232;

[0032] Multi-edge micro-tooth flat-bottom micro-milling cutter 3; flat-bottom micro-milling cutter handle 31; flat-bottom micro-milling cutter neck 32; flat-bottom micro-milling cutter cutting edge 33;

[0033] Multi-edge micro-tooth ball-end micro-milling cutter 4; ball-end micro-milling cutter handle 41; ball-end micro-milling cutter neck 42; ball-end micro-milling cutter head 43. Detailed implementation manners

[0034] The present invention will be further described in detail below with reference to the accompanying drawings.

[0035] As Figure 1 shown, the structure and function of a microchannel heat exchanger will be described in detail below;

[0036] A multi-scale recessed groove microchannel heat exchanger includes a metal microchannel substrate 2 and a cover plate 1 attached to the metal microchannel substrate 2. The material of the microchannel substrate 2 is copper or aluminum or stainless steel. A closed space is formed between the metal microchannel substrate 2 and the cover plate 1. A cooling working fluid inlet 11 is provided on one side of the cover plate 1, and a cooling working fluid outlet 12 is provided on the other side of the cover plate 1. An inlet liquid storage tank 21 and an outlet liquid storage tank 22 are respectively provided on both sides of the metal microchannel substrate 2. The inlet liquid storage tank 21 and the outlet liquid storage tank 22 are respectively communicated with the cooling working fluid inlet 11 and the cooling working fluid outlet 12. As Figure 1 shown, a plurality of microchannels 23 are provided on the metal microchannel substrate 2. The plurality of microchannels 23 are connected between the inlet liquid storage tank 21 and the outlet liquid storage tank 22. The microchannels 23 are used to connect the cooling working fluid inlet 11 and the cooling working fluid outlet 12. The microchannels 23 are concave structures with rough textures;

[0037] As Figure 6 and 7 shown, the concave structure is composed of a rectangular slit 231 and a recessed cavity 232;

[0038] The cross-section of the rough texture is triangular or trapezoidal. The height of the rough texture is 0.02 mm - 0.04 mm, and the distance between adjacent rough texture structures is 0.05 mm - 0.1 mm;

[0039] As Figure 1 shown, a plurality of microchannels 23 are arranged equidistantly and parallel to each other. Such a plurality of microchannels 23 arranged parallel to each other can reduce the processing difficulty and processing time and facilitate processing;

[0040] Preferably, the equivalent diameter of the recessed cavity 232 at the bottom of the microchannel is 0.6 mm - 1.0 mm, the width of the rectangular slit 231 at the top of the microchannel is 0.4 mm - 0.6 mm, the depth is 0.3 mm - 0.5 mm, and the distance between adjacent two microchannels 23 is 1.1 mm - 1.5 mm;

[0041] If Figures 1 to 7 As shown below, the steps and functions of a method for manufacturing a microchannel heat exchanger are described in detail by taking the processing of a plurality of microchannels 23 arranged parallel and equidistant to each other, and the transverse cross-section of the recessed cavity is circular as an example;

[0042] A method for manufacturing a microchannel heat exchanger comprises the following steps:

[0043] Step 1: Using cemented carbide as material, prepare a multi-edge micro-tooth flat-bottom micro-milling cutter 3 and a multi-edge micro-tooth ball-end micro-milling cutter 4;

[0044] Step 2: Select two polished copper plates, the sizes of which are respectively 35mm long × 20mm wide × 1mm high and 35mm long × 20mm wide × 2.5mm high, and fix the copper plates of 35mm long × 20mm wide × 1mm high on a vertical milling machine, and use micro-milling technology to process the cooling medium inlet 11 and the cooling medium outlet 12 on the copper plates to obtain the cover plate 1;

[0045] Step 3: Fix the copper plate of 35mm in length×20mm in width×2.5mm in height on the vertical milling machine, use micro-milling technology to process the inlet and outlet liquid storage tanks 22 and the outlet liquid storage tanks 23, and then use a multi-blade micro-tooth flat-bottom micro-milling cutter 3 with a diameter of 0.5mm at a feed speed of 120mm / min, a back cutting amount of 0.2mm, and a spindle speed of 15000r / min to process parallel array rectangular slits 231 with an interval of 1.3mm, a width of 0.5mm, and a depth of 0.8mm.

[0046] Step 4: Use the multi-blade micro-tooth ball-end micro-milling cutter 4 described in step 1 to perform tool alignment. On the copper plate with the rectangular slit 231 processed in step 3, move the tool along the center line direction of the rectangular slit 231. The feed speed is 40 mm / min, the back cutting amount is 1.1 mm, and the spindle speed is 13000 r / min. A circular cavity 232 is processed, and a large number of rough texture structures are distributed on the wall of the circular cavity 232;

[0047] Step 5: Clean the cover plate 1 processed in step 2 and the microchannel substrate 2 processed in step 4 in an ultrasonic cleaning machine filled with anhydrous ethanol for 20 minutes, and then take them out and dry them;

[0048] Step 6: Lay the lower surface of the cover plate 1 and the upper surface of the microchannel substrate 2 together, fix them by brazing, and connect them with the external pipe and water pump to form a whole, forming a forced circulation loop, and obtaining a complete microchannel heat exchanger.

[0049] A preparation method of a multi-scale recessed groove microchannel heat exchanger provided by this embodiment uses a multi-edge micro-tooth flat-bottomed and ball-headed micro-milling cutter to machine a number of recessed groove microchannels arranged in parallel at equal intervals, and form a rough texture structure on the wall surface of the microchannels, thereby significantly increasing the surface roughness and heat transfer area, providing sufficient vaporization nuclei for bubble nucleation, and having a good heat transfer enhancement effect. In addition, by using a multi-edge micro-tooth flat-bottomed and ball-headed micro-milling cutter, while machining rectangular slits and recessed cavities, the integrated forming of the rough texture structure on the wall surface can be realized, without secondary processing technology, the manufacturing process is simple, the processing cost is low, the processing accuracy is high, and the high-efficiency and low-cost preparation and forming of the heat transfer enhancement structure in the micro-scale channel can be realized.

[0050] The above embodiments are only used to further illustrate a recessed groove microchannel heat exchanger with a rough texture structure and its manufacturing method, but the present invention is not limited to the embodiments. Any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention are all included in the protection scope of the present invention.

Claims

1. A method for manufacturing a multi-scale sunken groove microchannel heat exchanger, characterized in that: The microchannel heat exchanger comprises a metal microchannel substrate (2) and a cover plate (1) attached to the metal microchannel substrate (2); a cooling medium inlet (11) is provided on one side of the cover plate (1), and a cooling medium outlet (12) is provided on the other side of the cover plate (1); a plurality of microchannels (23) are provided on the metal microchannel substrate (2); the microchannels (23) are used to connect the cooling medium inlet (11) and the cooling medium outlet (12); and the microchannels (23) are in the form of an indented groove structure with a rough texture on the wall surface; The sunken groove is composed of a rectangular slit (231) and a circular cavity (232); An inlet liquid reservoir (21) and an outlet liquid reservoir (22) are respectively arranged on both sides of the metal microchannel substrate (2); the inlet liquid reservoir (21) and the outlet liquid reservoir (22) are respectively connected to the cooling medium inlet (11) and the cooling medium outlet (12); and a plurality of microchannels (23) are connected between the inlet liquid reservoir (21) and the outlet liquid reservoir (22); The manufacturing method comprises the following steps: Step 1: preparing a multi-blade micro-tooth flat-bottom micro-milling cutter (3) and a multi-blade micro-tooth ball-end micro-milling cutter (4); Step 2: Selecting a first metal plate and a second metal plate as the cover plate (1) and the metal microchannel substrate (2); Step 3: a multi-blade micro-tooth flat-bottom micro-milling cutter (3) is used to process the second metal plate to form a plurality of rectangular slits (231); Step 4: a multi-blade micro-tooth ball-end micro-milling cutter (4) processes the second metal plate along the center line of the rectangular slit (231) to form a concave cavity (232); Step 5: The cover plate (1) and the metal microchannel substrate (2) are fixedly connected and connected with external pipes and a water pump to form a whole, thereby forming a forced circulation loop and obtaining a complete microchannel heat exchanger; The multi-blade micro-tooth flat-bottom micro-milling cutter (3) and the multi-blade micro-tooth ball-end micro-milling cutter (4) both have multiple cutting edges; The cutting edges of the multi-blade micro-tooth flat-bottom micro-milling cutter (3) and the multi-blade micro-tooth ball-end micro-milling cutter (4) are discretized into micro-tooth structures; Rough texture structures are distributed inside the rectangular slit (231) and the concave cavity (232).

2. The method for manufacturing a multi-scale sunken groove microchannel heat exchanger according to claim 1, characterized in that: The cross section of the rough texture is a triangle.

3. The method for manufacturing a multi-scale sunken groove microchannel heat exchanger according to claim 1, characterized in that: The cross section of the rough texture is trapezoidal.

4. The method for manufacturing a multi-scale sunken groove microchannel heat exchanger according to claim 1, characterized in that: The plurality of microchannels (23) are equidistant and parallel to each other.

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