Copper water heat pipe based on laser enhanced capillary performance and machining method of copper water heat pipe

Abstract

The invention discloses a copper water heat pipe based on laser enhanced capillary performance and a machining method thereof.The copper water heat pipe comprises a pipe body, a pipe cavity is formed in the pipe body, a first capillary structure composed of a plurality of grooves is arranged on the inner side wall of the pipe body, and the grooves are evenly distributed around the inner side wall of the pipe body at equal angles; the inner wall of the groove is provided with a micron-sized groove, the surface of the micron-sized groove is provided with nano-sized pores, the two ends of the pipe body are sealed, and the pipe cavity is filled with a liquid working medium, so that the capillary performance of the copper water heat pipe can be improved on the basis of not introducing other elements, and the heat transfer capacity of the heat pipe is further improved.

Description

Technical Field

[0001] The present application relates to the technical field of aerospace heat dissipation equipment, and in particular to a copper-water heat pipe based on laser-enhanced capillary properties and a processing method thereof. Background Art

[0002] Copper-water heat pipes are components that achieve heat transfer through internal ultrapure water vapor-liquid phase change. They have the advantages of ultra-high thermal conductivity, heat flow reversibility, and good environmental adaptability. In order to avoid the harm caused by vibration during launch and operation, heat pipes for aerospace use often use axial grooved liquid wick structures. However, due to the limitations of the groove structure, the capillary limit power of traditional axial grooved liquid wicks cannot meet the heat dissipation requirements of aerospace devices.

[0003] In order to meet the high-power heat dissipation requirements of devices, chemical treatment is often used to improve the capillary capacity of copper-water heat pipes. However, chemical treatment often introduces other elements, making it unable to meet the requirements of aerospace, and it is very difficult to prepare micro-nanoscale structures on the inner wall of the tube shell by mechanical means. Therefore, it is very necessary to improve the capillary performance of heat pipes without introducing other elements, improve the heat transfer capacity of heat pipes, and meet the heat transfer capacity requirements of aerospace and microelectronics fields. Summary of the invention

[0004] The first technical problem to be solved by the present application is to provide a copper-water heat pipe based on laser-enhanced capillary performance, so as to solve the technical problem of how to improve the capillary performance of the heat pipe without introducing other elements and further enhance the heat transfer capacity of the heat pipe.

[0005] The second technical problem to be solved by the present application is to provide a method for processing a copper-water heat pipe based on laser-enhanced capillary properties.

[0006] To solve the above-mentioned first technical problem, the technical solution of this application is:

[0007] A copper-water heat pipe based on laser enhanced capillary performance comprises a tube body, a tube cavity is arranged inside the tube body, a plurality of grooves are arranged on the inner wall of the tube body to form a first capillary structure, the plurality of grooves are evenly distributed at equal angles around the inner wall of the tube body, micrometer-level grooves are arranged on the inner wall of the groove, the micrometer-level groove surface has nanometer-level pores, the two ends of the tube body are sealed, and the tube cavity is filled with liquid working medium.

[0008] Preferably, a micron-scale groove with nano-scale pores on the surface is provided on the inner side wall of the tube body between any two adjacent first capillary structure grooves.

[0009] Preferably, the groove cross-sectional depth is 0.2mm-0.4mm, the width is 0.1-0.3mm, and the aspect ratio is greater than 1.5; the micron-scale groove is 10-30μm wide and 10-40μm deep; the nanoscale pores are irregular pores with a diameter of 20-150nm and a depth of 20-60nm.

[0010] Preferably, the tube body is made of copper.

[0011] Preferably, the liquid working medium is ultrapure water, the tube cavity is in a vacuum or negative pressure state, and the interior of the heat pipe is filled with the liquid working medium which accounts for 50% to 150% of the volume of the capillary structure of the first size.

[0012] The processing method of the copper-water heat pipe based on laser enhanced capillary performance of the present application comprises the following steps:

[0013] (1) Broaching grooves: A broaching process is used to broach a groove of a first capillary structure on the inner wall of the tube body;

[0014] (2) Guide rail installation: Slidingly install the indexing chuck on the horizontal guide rail, and clamp the tube body on the indexing chuck so that the central axis of the tube body is parallel to the guide rail;

[0015] (3) Laser etching: using an infrared nanosecond laser to etch the inner wall of the tube body through optical fiber transmission, so that the tube body slides along the guide rail at a uniform speed to form a micron-scale groove with nano-scale pores on the inner wall of the tube body, and using a graduated chuck to index and position the tube body, and etching is performed on the inner wall of the tube body with the help of a reflector;

[0016] (4) reduction annealing: placing the tube body obtained in step (3) in a mixed atmosphere for high temperature annealing to reduce the copper oxide formed by nanosecond laser ablation to copper;

[0017] (5) Filling with working fluid: Seal one end of the tube obtained in step (4), fill the other end with liquid working fluid, and seal the tube opening after evacuating the air using a vacuum pump.

[0018] Preferably, the mixed atmosphere is a mixture of nitrogen and hydrogen, wherein the nitrogen accounts for 95% and the hydrogen accounts for 5%.

[0019] Preferably, in step (3), the power of the infrared nanosecond laser generator is 15W to 50W.

[0020] The technical effects achieved by adopting the above technical solution are:

[0021] The present application uses an infrared nanosecond laser to etch a second capillary structure composed of micron-scale grooves and nanometer-scale pores on the axial groove surface of the inner wall of the tube body, and improves the wettability of the axial groove surface of the first capillary structure by increasing the roughness of the tube cavity side wall. At the same time, the micron-scale grooves and nanometer-scale pores on the side wall of the tube body can improve the penetration ability of the liquid working medium, thereby further improving the capillary performance, achieving the effect of improving the capillary limit power of the heat pipe and improving the heat transfer capacity of the heat pipe, which can meet the requirements of the aviation, aerospace and microelectronics fields for the heat transfer capacity of the heat pipe.

[0022] Since a micron-sized groove is provided on the inner wall of the tube body between any two adjacent grooves, the surface of the micron-sized groove has nano-sized pores, and the second capillary structure is distributed on the surface of the entire tube body groove, the capillary effect can be effectively increased, the reflux speed of the liquid working medium can be increased, and thus the heat dissipation capacity can be improved.

[0023] Since the liquid working medium is ultrapure water, the tube cavity is in a vacuum or negative pressure state, and the tube cavity is filled with a liquid working medium that accounts for 50% to 150% of the volume of the first-size capillary structure. The resistivity of ultrapure water reaches 18MΩ*cm, which is an insulating state. This water has almost no impurities, ensuring that the copper water will not undergo chemical and electrochemical reactions. At the same time, ultrapure water has good comprehensive thermophysical properties, is non-toxic and harmless, and is inexpensive.

[0024] The processing method of the copper-water heat pipe based on laser enhanced capillary performance adopts infrared nanosecond laser etching on the inner wall of the tube body to form a second capillary structure. The second capillary structure can further improve the surface roughness of the tube groove, thereby improving the wettability of the tube groove surface. The micron-level grooves and nano-level pores formed on the surface can improve the penetration ability of the liquid working medium, which is beneficial to the diffusion and distribution of the liquid working medium on the tube wall, further enhance the capillary performance of the axial groove, improve the capillary limit power of the heat pipe, and promote the reflux of the liquid working medium to meet the requirements of the heat transfer capacity of the heat pipe in the fields of aviation, aerospace and microelectronics. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present application is further described below in conjunction with the accompanying drawings and embodiments.

[0026] Figure 1 This is a schematic diagram of the internal structure of a copper-water heat pipe based on laser-enhanced capillary properties;

[0027] Figure 2 It is a schematic cross-sectional view of a copper-water heat pipe based on laser-enhanced capillary properties;

[0028] Figure 3 It is a schematic diagram of a copper tube processing method based on laser enhanced capillary performance;

[0029] In the figure, 1. laser generator; 2. guide rail sliding device; 3. reflector; 4. dividing chuck; 5. tube body; 6. optical fiber; 7. first capillary structure; 8. second capillary structure. DETAILED DESCRIPTION

[0030] like Figures 1-2 As shown, a copper-water heat pipe based on laser enhanced capillary performance includes a tube body 5, which is preferably made of copper. A tube cavity is provided inside the tube body 5, and a plurality of grooves are provided on the inner side wall of the tube body 5 to form a first capillary structure 7, the groove cross-sectional depth is 0.2 mm to 0.4 mm, the width is 0.1 to 0.3 mm, and the depth-to-width ratio is greater than 1.5; the plurality of grooves are evenly distributed around the inner side wall of the tube body 5 at equal angles.

[0031] The inner wall of the groove is provided with a micron-scale groove, and the surface of the micron-scale groove has nano-scale pores, and the micron-scale groove and the nano-scale pores constitute a second capillary structure. Furthermore, between any two adjacent first capillary structure grooves, a micron-scale groove with nano-scale pores on the inner wall of the tube body 5 is provided. The micron-scale groove is 10 to 30 μm wide and 10 to 40 μm deep; the nano-scale pores are irregular pores with a diameter of 20 to 150 nm and a depth of 20 to 60 nm.

[0032] The two ends of the tube body 5 are sealed, and the tube cavity is filled with liquid medium. The liquid medium is ultrapure water, and the tube cavity is in a vacuum or negative pressure state. The tube cavity is filled with liquid medium that accounts for 50% to 150% of the volume of the first size capillary structure. The resistivity of ultrapure water reaches 18MΩ*cm, which is an insulating state. This water has almost no impurities, ensuring that the copper water will not undergo chemical and electrochemical reactions. At the same time, the water has good comprehensive thermophysical properties, is non-toxic, harmless, environmentally friendly, and inexpensive.

[0033] like Figure 3 As shown, the processing method of the copper-water heat pipe based on laser enhanced capillary performance includes the following steps:

[0034] (1) Groove Broaching: A groove of the first capillary structure 7 is broached on the inner wall of the tube body 5 by a broaching process.

[0035] (2) Guide rail installation: The indexing chuck 4 is slidably installed on the guide rail of the guide rail sliding device 2, and the guide rail is set horizontally. The tube body 5 is clamped on the indexing chuck 4 so that the central axis of the tube body 5 is parallel to the guide rail.

[0036] (3) Laser etching: The laser generator 1 emits an infrared nanosecond laser, which is used to etch the inner wall of the tube body 5 through the optical fiber 6. A reflector 3 is installed at the end of the optical fiber 6. The infrared nanosecond laser is reflected by the reflector to the bottom, inner side and spacing surface of the axial groove for etching. The power of the infrared nanosecond laser generator 1 is 15W to 50W. The tube body 5 slides at a uniform speed along the guide rail on the inner wall to form a micron-sized groove with nanometer-sized pores on the surface. The tube body 5 is indexed and positioned using the indexing chuck 4.

[0037] (4) Reduction annealing: The tube body 5 obtained in step (3) is placed in a mixed atmosphere for high temperature annealing to reduce the copper oxide formed by nanosecond laser ablation to copper. The mixed atmosphere is a mixture of nitrogen and hydrogen, wherein nitrogen accounts for 95% and hydrogen accounts for 5%.

[0038] (5) Filling with working fluid: one end of the tube body 5 obtained in step (4) is sealed, and the other end is filled with liquid working fluid, and the tube opening is sealed after evacuating air with a vacuum pump.

[0039] The working principle of the heat pipe in this application is:

[0040] The copper-water heat pipe based on laser enhanced capillary performance of the present application has one end as the evaporation end and the other end as the condensation end. When one end of the heat pipe is heated, the liquid working medium in the first capillary structure 7 and the second capillary structure 8 is rapidly vaporized, and the steam flows to the other end under the action of the steam pressure, and condenses at the cold end to release heat. The liquid working medium then flows back to the evaporation end along the first and second capillary structures by capillary action, and the cycle repeats until the temperatures at both ends of the heat pipe are equal (at this time, the heat absorbed by the hot end is equal to the heat released by the cold end). This cycle is carried out quickly, and the heat can be continuously conducted, thereby realizing the function of heat dissipation.

[0041] The copper-water heat pipe based on laser-enhanced capillary performance of the present application is used in the aerospace field to quickly transfer the heat accumulated by heat-generating components such as chips, solving the problem of untimely heat diffusion. The copper-water heat pipe uses the phase change process of the liquid working medium absorbing heat and evaporating at the hot end and releasing heat and condensing at the cold end (that is, using the latent heat of evaporation and condensation of the liquid) to quickly conduct heat.

Claims

1. A copper-water heat pipe based on laser-enhanced capillary properties, characterized in that: It includes a tube body, a tube cavity is arranged inside the tube body, a plurality of grooves are arranged on the inner wall of the tube body to form a first capillary structure, the plurality of grooves are evenly distributed at equal angles around the inner wall of the tube body, micron-sized grooves are arranged on the inner wall of the groove, the surface of the micron-sized grooves has nano-sized pores, the two ends of the tube body are sealed, and the tube cavity is filled with liquid working medium.

2. The copper-water heat pipe based on laser enhanced capillary performance according to claim 1, characterized in that: A micron-scale groove with nano-scale pores on the surface is provided on the inner side wall of the tube body between any two adjacent first capillary structure grooves.

3. The copper-water heat pipe based on laser enhanced capillary performance as claimed in claim 2, characterized in that: The groove cross-section has a depth of 0.2 mm to 0.4 mm, a width of 0.1 mm to 0.3 mm, and an aspect ratio greater than 1.5; the micron-scale groove has a width of 10 to 30 μm and a depth of 10 to 40 μm; the nanoscale pore has a diameter of 20 to 150 nm and a depth of 20 to 60 nm.

4. The copper-water heat pipe based on laser enhanced capillary performance as claimed in claim 3, characterized in that: The tube body is made of copper.

5. The copper-water heat pipe based on laser enhanced capillary performance as claimed in claim 4, characterized in that: The liquid working medium is ultrapure water, the interior of the tube cavity is in a vacuum or negative pressure state, and the interior of the tube cavity is filled with the liquid working medium which accounts for 50% to 150% of the volume of the first capillary structure.

6. The method for processing a copper-water heat pipe based on laser enhanced capillary performance according to claim 1, characterized in that: The following steps are involved: (1) Broaching grooves: A broaching process is used to broach a groove of a first capillary structure on the inner wall of the tube body; (2) Guide rail installation: Slidingly install the indexing chuck on the horizontal guide rail, and clamp the tube body on the indexing chuck so that the central axis of the tube body is parallel to the guide rail; (3) Laser etching: using an infrared nanosecond laser to etch the inner wall of the tube body through optical fiber transmission, so that the tube body slides along the guide rail at a uniform speed to form a micron-scale groove with nano-scale pores on the inner wall of the tube body, and using a graduated chuck to index and position the tube body, and etching is performed on the inner wall of the tube body with the help of a reflector; (4) reduction annealing: placing the tube body obtained in step (3) in a mixed atmosphere for high temperature annealing to reduce the copper oxide formed by nanosecond laser ablation to copper; (5) Filling with working fluid: Seal one end of the tube obtained in step (4), fill the other end with liquid working fluid, and seal the tube opening after evacuating the air using a vacuum pump.

7. The method for processing a copper-water heat pipe based on laser enhanced capillary performance according to claim 6, characterized in that: The mixed atmosphere is a mixture of nitrogen and hydrogen, wherein the nitrogen accounts for 95% and the hydrogen accounts for 5%.

8. The method for processing a copper-water heat pipe based on laser enhanced capillary performance according to claim 7, characterized in that: In step (3), the power of the infrared nanosecond laser generator is 15 to 50 W.

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