Copper water heat pipe based on laser enhanced capillary performance

Abstract

The copper water heat pipe comprises a pipe body, a pipe cavity is formed in the pipe body, a plurality of grooves are formed in the inner side wall of the pipe body to form a first capillary structure, the grooves are evenly distributed around the inner side wall of the pipe body at equal angles, micron-sized grooves are formed in the inner walls of the grooves, and the micron-sized grooves are evenly distributed around the inner side wall of the pipe body. Nanoscale pores are formed in the surfaces of the micron-scale grooves, the two ends of the pipe body are sealed, the pipe cavity is filled with a liquid working medium, the capillary performance of the copper water heat pipe can be improved on the basis that other elements are not introduced, 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. Background Art

[0002] Copper-water heat pipes are components that transfer heat through the vapor-liquid phase transition of ultrapure water within them. They offer advantages such as ultra-high thermal conductivity, reversible heat flow, and excellent environmental adaptability. To mitigate the harmful effects of vibration during launch and operation, aerospace heat pipes often utilize an axially grooved wick structure. However, due to the limitations of the groove structure, the capillary power limit of traditional axially grooved wicks cannot meet the cooling requirements of aerospace components.

[0003] 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 unsuitable for aerospace applications. Mechanically fabricating micro- and nanoscale structures on the inner wall of the tube shell is also very difficult. Therefore, it is necessary to improve the capillary performance of heat pipes without introducing other elements, thereby increasing the heat transfer capacity of heat pipes and meeting the heat transfer requirements of aerospace and microelectronics. Utility Model Content

[0004] The technical problem to be solved by this 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] To solve the above technical problems, the technical solution of this application is:

[0006] A copper-water heat pipe with laser-enhanced capillary properties includes a tube body, a tube cavity is provided inside the tube body, a plurality of grooves are provided 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-scale grooves are provided on the inner wall of the grooves, and the surfaces of the micron-scale grooves have nanoscale pores. Both ends of the tube body are sealed, and the tube cavity is filled with a liquid working medium.

[0007] 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.

[0008] Preferably, 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 pores are irregular pores with a diameter of 20 to 150 nm and a depth of 20 to 60 nm.

[0009] Preferably, the tube body is made of copper.

[0010] 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 that accounts for 50% to 150% of the volume of the first-size capillary structure.

[0011] The technical effects achieved by adopting the above technical solution are:

[0012] This application uses an infrared nanosecond laser to etch a second capillary structure consisting of micron-scale grooves and nanoscale pores on the axial groove surface of the inner wall of the tube body. By increasing the roughness of the tube cavity side wall, the wettability of the axial groove surface of the first capillary structure is improved. At the same time, the micron-scale grooves and nanoscale 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 increasing 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.

[0013] Since a micron-scale groove is provided on the inner wall of the tube body between any two adjacent grooves, and the surface of the micron-scale groove has nano-scale pores, the second capillary structure is distributed on the surface of the entire tube groove, which can effectively increase the capillary effect and increase the reflux speed of the liquid working medium, thereby improving the heat dissipation capacity.

[0014] Because the liquid working fluid is ultrapure water, the tube cavity is in a vacuum or negative pressure state, and the liquid working fluid accounts for 50% to 150% of the volume of the first-dimension capillary structure. Ultrapure water has a resistivity of 18MΩ*cm, which is an insulating state. This water is almost impurity-free, ensuring that the copper water does not undergo chemical or electrochemical reactions. Ultrapure water also has excellent comprehensive thermophysical properties, is non-toxic, and is inexpensive. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The present application is further described below with reference to the accompanying drawings and examples.

[0016] Figure 1 This is a schematic diagram of the internal structure of a copper-water heat pipe based on laser-enhanced capillary properties;

[0017] Figure 2 This is a schematic cross-sectional view of a copper-water heat pipe based on laser-enhanced capillary properties;

[0018] Figure 3 This is a schematic diagram of a copper tube processing method based on laser-enhanced capillary properties;

[0019] In the figure, 1. laser generator; 2. guide rail sliding device; 3. reflector; 4. indexing chuck; 5. tube body; 6. optical fiber; 7. first capillary structure; 8. second capillary structure. DETAILED DESCRIPTION

[0020] like Figures 1-2 As shown, a copper-water heat pipe with laser-enhanced capillary properties includes a tube body 5, preferably made of copper. Tube body 5 has a lumen within it, and the inner wall of tube body 5 is provided with a plurality of grooves forming a first capillary structure 7. The grooves have a cross-sectional depth of 0.2 mm to 0.4 mm, a width of 0.1 mm to 0.3 mm, and a depth-to-width ratio greater than 1.5. The grooves are evenly distributed at equal angles around the inner wall of tube body 5.

[0021] The inner wall of the groove is provided with micron-scale grooves, and the surface of the micron-scale grooves has nanoscale pores. The micron-scale grooves and nanoscale pores form a second capillary structure. Furthermore, between any two adjacent first capillary structure grooves, a micron-scale groove with nanoscale pores on the inner wall of the tube body 5 is provided. The micron-scale grooves are 10-30 μm wide and 10-40 μm deep; the nanoscale pores are irregular pores with a diameter of 20-150 nm and a depth of 20-60 nm.

[0022] The tube body 5 is sealed at both ends, and the tube cavity is filled with a liquid working medium. The liquid working medium is ultrapure water. The tube cavity is in a vacuum or negative pressure state, and the liquid working medium occupies 50% to 150% of the volume of the first-dimension capillary structure. Ultrapure water has a resistivity of 18MΩ*cm, which is an insulating state. This water is almost free of impurities, ensuring that the copper water does not undergo chemical and electrochemical reactions. At the same time, this water has excellent comprehensive thermophysical properties, is non-toxic, environmentally friendly, and inexpensive.

[0023] like Figure 3 As shown, the processing method of the copper-water heat pipe based on laser-enhanced capillary performance includes the following steps:

[0024] (1) Broaching grooves: A broaching process is used to broach a groove of the first capillary structure 7 on the inner wall of the tube body 5 .

[0025] (2) Guide rail installation: Slide the indexing chuck 4 onto the guide rail of the guide rail sliding device 2. The guide rail is set horizontally. Clamp the tube body 5 onto the indexing chuck 4 so that the central axis of the tube body 5 is parallel to the guide rail.

[0026] (3) Laser etching: The laser generator 1 emits an infrared nanosecond laser, which is transmitted through the optical fiber 6 to etch the inner wall of the tube body 5. 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-level groove with nanometer-level pores on the surface. The tube body 5 is indexed and positioned using the indexing chuck 4.

[0027] (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%.

[0028] (5) Filling with working medium: Seal one end of the tube body 5 obtained in step (4), fill the other end with liquid working medium, and seal the tube mouth after evacuating the air using a vacuum pump.

[0029] The working principle of the heat pipe of this application is:

[0030] The copper-water heat pipe based on laser-enhanced capillary properties 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 quickly vaporizes. The vapor flows to the other end under the action of steam pressure and condenses at the cold end, releasing heat. The liquid working medium then flows back to the evaporation end along the first and second capillary structures by capillary action. This 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 rapidly, and heat can be conducted continuously, thereby achieving the function of heat dissipation.

[0031] The copper-water heat pipe, based on laser-enhanced capillary properties, is used in the aerospace industry to quickly transfer heat accumulated in heat-generating components such as chips, solving problems such as delayed heat dissipation. The copper-water heat pipe utilizes the phase change process of a liquid working fluid absorbing heat and evaporating at the hot end before releasing heat and condensing at the cold end (i.e., utilizing the liquid's latent heat of vaporization and condensation), enabling rapid heat transfer.

Claims

1. A copper-water heat pipe based on laser-enhanced capillary properties, characterized in that: It includes a tube body, a tubular cavity is provided inside the tube body, a plurality of grooves are provided 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-scale grooves are provided on the inner wall of the grooves, and the surface of the micron-scale grooves has nano-scale pores. The two ends of the tube body are sealed, and the tubular cavity is filled with liquid working medium.

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

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

5. The copper-water heat pipe based on laser-enhanced capillary properties according to 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.

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