Large-length-diameter-ratio trunk-type sintered wick high-temperature heat pipe and preparation method thereof

Abstract

The invention provides a large-length-diameter-ratio main road type sintered wick high-temperature heat pipe and a preparation method thereof, and belongs to the technical field of high-temperature heat pipes. The high-temperature heat pipe comprises a pipe shell, an end cover, a porous wick, a wire mesh trunk and a liquid metal working medium, and the porous wick, the tube shell and the wire mesh trunk are integrally sintered and molded. According to the high-temperature heat pipe, the porous wick, the pipe shell and the silk screen main road are integrally sintered and formed, the contact thermal resistance can be reduced, the porous wick has high capillary force and large heat exchange area, the silk screen main road has high permeability, the heat transfer efficiency of the high-temperature heat pipe can be remarkably improved, and the heat transfer distance of the high-temperature heat pipe can be remarkably increased. When the preparation method is adopted to prepare the large-length-diameter-ratio trunk line type sintered wick high-temperature heat pipe, the middle core rod is easy to draft, impurities such as a release agent which pollutes the wick are not introduced, the problem that the high-temperature heat pipe is difficult to draft is solved, and the preparation method can be used for standardized and batch production of the large-length-diameter-ratio trunk line type wick high-temperature heat pipe.

Description

Technical Field

[0001] The present invention relates to the technical field of high-temperature heat pipes, and in particular to a large aspect ratio main channel type sintered liquid wick high-temperature heat pipe and a preparation method thereof. Background Art

[0002] High-temperature heat pipes use liquid metal as phase change medium, and have the advantages of high working temperature, large heat transfer, and high heat transfer efficiency. They have broad application prospects in nuclear energy systems, hypersonic aircraft thermal protection, molten salt reactor energy conversion systems, and other fields. Traditional high-temperature heat pipe wicks are mainly based on wire mesh structures and groove structures. Among them, the wire mesh structure has been widely studied due to its simple preparation process and high permeability of wire mesh wicks. There are few reports on the preparation of sintered wick high-temperature heat pipes. On the one hand, it is difficult to sinter high-temperature heat pipes with large aspect ratios due to the limitations of sintering equipment; on the other hand, there are problems such as difficulty in core rod demolding during the preparation of sintered wicks with large aspect ratios, and the introduced demolding agent will contaminate the liquid metal medium with higher purity. Therefore, it is of great significance to study a preparation method for a high-temperature heat pipe with a large aspect ratio main channel sintered wick. Summary of the invention

[0003] The purpose of the present invention is to provide a large aspect ratio main channel sintered liquid wick high temperature heat pipe and a preparation method thereof, so as to solve the problems in the prior art that large aspect ratio high temperature heat pipes are difficult to sinter in an integrated manner and the core rod is difficult to demold.

[0004] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0005] The invention provides a high-temperature heat pipe with a large aspect ratio main channel sintered liquid wick, comprising a tube shell, an end cover, a porous liquid wick, a wire mesh main channel and a liquid metal working medium; the porous liquid wick, the tube shell and the wire mesh main channel are integrally sintered.

[0006] Preferably, the end caps are located at both ends of the tube shell; and the porous liquid-absorbing core is attached to the inner wall of the tube shell.

[0007] Preferably, the porosity of the porous liquid absorbent core is 40-80%.

[0008] Preferably, the aperture of the wire mesh in the wire mesh trunk is 200-800 meshes, and the number of layers of the wire mesh is 2-4 layers.

[0009] Preferably, the wire mesh trunk is located inside the porous liquid absorbent core.

[0010] The present invention also provides a method for preparing the above-mentioned large aspect ratio main channel sintered liquid wick high temperature heat pipe, comprising the following steps:

[0011] (1) Winding the wire mesh on a metal rod and fixing it to obtain a wire mesh main channel mold;

[0012] (2) Insert the magnetic suction sleeve into the outer wall of the tube shell at intervals, and then place the wire mesh main channel mold in the tube shell, and adhere it to the inner wall of the tube shell under the action of magnetic force;

[0013] (3) placing a core rod in a tension spring to obtain a core rod mold, and then placing the core rod mold in the center of the tube shell, filling the metal powder into the gap between the tube shell and the tension spring, and then sintering;

[0014] (4) After sintering is completed, the tension spring is pulled out, and then the end covers are welded at both ends of the tube shell, and finally the liquid metal working medium is filled to obtain a high-temperature heat pipe with a large aspect ratio and a dry channel sintered liquid absorption core.

[0015] Preferably, in step (1), the diameter of the metal rod is 0.5 to 3 mm.

[0016] Preferably, in the step (2), the magnetic sleeve has a positioning hole and a magnet embedding hole, wherein the positioning hole is used to place the positioning rod, and the magnet embedding hole is used to place the magnet; the magnet can magnetically attract the wire mesh main channel mold to the inner wall of the tube shell, and the positions of the magnet and the wire mesh main channel mold correspond one to one.

[0017] Preferably, in step (3), a plug is inserted into the bottom of the tension spring; the core rod mold is placed in the center of the tube shell, and a plug is inserted into the top of the tube shell, and a through hole is provided on the plug.

[0018] Preferably, in step (4), the sintering temperature is 1150-1200° C., and the sintering time is 1-3 hours.

[0019] Beneficial effects of the present invention:

[0020] (1) The high-temperature heat pipe with a large aspect ratio and a main channel sintered liquid absorbent core of the present invention is formed by sintering a porous liquid absorbent core, a tube shell and a wire mesh main channel in one piece. The porous sintered liquid absorbent core has the advantages of small contact thermal resistance, adjustable pore size and porosity, large capillary force, and large heat exchange area. The wire mesh main channel has high permeability. The combination of the two can significantly improve the heat transfer efficiency and heat transfer distance of the high-temperature heat pipe.

[0021] (2) The preparation method of the present invention is used to prepare a large aspect ratio main channel sintered liquid wick high temperature heat pipe. The core rod in the middle is easy to demold without introducing impurities such as mold release agents that contaminate the liquid wick, thereby solving the problem of difficulty in demolding the high temperature heat pipe. The technical solution is simple, the operation is simple, and the feasibility is high. It can be used for the standardized and mass production of main channel liquid wick high temperature heat pipes. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1Schematic cross-sectional view of a high-temperature heat pipe with a large aspect ratio main channel sintered liquid wick according to the present invention, wherein 1 is a tube shell, 2 is a porous liquid wick, 3 is a wire mesh main channel, 4 is a left end cap, and 5 is a right end cap with a liquid filling port;

[0023] Figures 2 to 9 Schematic diagram of the preparation process of the high-length-diameter-ratio main channel sintered liquid-absorbing core high-temperature heat pipe of Example 1 of the present invention, wherein Figure 2 3-1 is a round iron rod, and 3-2 is a wire mesh; Figure 3 1 is a stainless steel tube shell, 6-1 is a magnetic suction sleeve, 6-2 is a stainless steel cylindrical positioning rod, and 6-3 is a cylindrical magnet; Figure 4 7-1 is the middle core rod, 7-2 is the compression spring, 8-1 is the stainless steel plug, 8-2 is the plug with a through hole, 8-3 is the through hole on the plug 8-2, and 8-4 is the plug; Figure 8 3 in the middle is a wire mesh trunk formed by sintering the round iron rod 3-1 and the wire mesh 3-2; Fig. 9 4 is an end cap, 5 is an end cap with a liquid filling hole, and the same reference numerals in different drawings represent the same parts. DETAILED DESCRIPTION

[0024] The invention provides a high-temperature heat pipe with a large aspect ratio main channel sintered liquid wick, comprising a tube shell, an end cover, a porous liquid wick, a wire mesh main channel and a liquid metal working medium; the porous liquid wick, the tube shell and the wire mesh main channel are integrally sintered.

[0025] In the present invention, the end caps are located at both ends of the tube shell; and the porous liquid wick is attached to the inner wall of the tube shell.

[0026] In the present invention, the porosity of the porous liquid absorbent core is 40 to 80%, preferably 50 to 70%, and more preferably 68%.

[0027] In the present invention, the aperture of the wire mesh in the wire mesh trunk is 200-800 mesh, preferably 300-600 mesh, and more preferably 400-500 mesh. The number of layers of the wire mesh is 2-4 layers, and preferably 3 layers.

[0028] In the present invention, the wire mesh is preferably a wire mesh woven in a twill or plain weave manner.

[0029] In the present invention, the wire mesh trunk is located inside the porous liquid absorbent core.

[0030] In the present invention, the tube shell, end cover, porous wick and wire mesh in the wire mesh trunk are preferably made of iron-based alloy, nickel-based high-temperature alloy, cobalt-based high-temperature alloy, molybdenum and its alloys, tungsten and its alloys, niobium and its alloys.

[0031] The present invention also provides a method for preparing the above-mentioned large aspect ratio main channel sintered liquid wick high temperature heat pipe, comprising the following steps:

[0032] (1) Winding the wire mesh on a metal rod and fixing it to obtain a wire mesh main channel mold;

[0033] (2) Insert the magnetic suction sleeve into the outer wall of the tube shell at intervals, and then place the wire mesh main channel mold in the tube shell, and adhere it to the inner wall of the tube shell under the action of magnetic force;

[0034] (3) placing a core rod in a tension spring to obtain a core rod mold, and then placing the core rod mold in the center of the tube shell, filling the metal powder into the gap between the tube shell and the tension spring, and then sintering;

[0035] (4) After sintering is completed, the tension spring is pulled out, and then the end covers are welded at both ends of the tube shell, and finally the liquid metal working medium is filled to obtain a high-temperature heat pipe with a large aspect ratio and a dry channel sintered liquid absorption core.

[0036] In the present invention, in step (1), the diameter of the metal rod is 0.5 to 3 mm, preferably 1 to 2 mm. The cross-sectional shape of the metal rod is preferably circular or crescent-shaped.

[0037] In the present invention, in the step (1), the wire mesh is wound around the metal rod, and preferably the bottom of the wire mesh is folded and closed.

[0038] In the present invention, in the step (2), the magnetic sleeve has a positioning hole and a magnet embedding hole, wherein the positioning hole is used to place the positioning rod, and the magnet embedding hole is used to place the magnet; the magnet can magnetically attract the wire mesh main channel mold to the inner wall of the tube shell, and the positions of the magnet and the wire mesh main channel mold correspond one to one.

[0039] In the present invention, the magnetic sleeve is inserted into the outer wall of the tube shell in sections and intervals; the positioning rod passes through the positioning hole of the magnetic sleeve; the number of the positioning holes is preferably 2 to 5, and more preferably 3 to 4; the number of the magnet embedding holes is determined according to the number of wire mesh main channels.

[0040] In the present invention, in step (3), the bottom of the tension spring is plugged into a plug; the core rod mold is placed in the center of the tube shell, and the top of the tube shell is plugged into the plug, and a through hole is provided on the plug. The through hole is used to load metal powder into the gap between the tube shell and the tension spring.

[0041] In the present invention, when the metal powder is loaded into the gap between the tube shell and the tension spring, it is continuously vibrated during the filling process, and the particle size of the metal powder is preferably 100 to 200 meshes; when the metal powder is filled to a distance of 1 cm from the tube shell, the metal rod in step (1) and the plug on the top of the tube shell are removed, and the excess wire mesh at the end is folded and sealed to bury it in the metal powder, and then a small amount of metal powder is continued to be filled so that the wire mesh is completely buried by the metal powder, and then the plug is inserted into the top of the tube shell to prevent the metal powder from leaking out.

[0042] In the present invention, before sintering, it is preferred to remove the magnetic sleeve, take out the core rod, and then perform sintering.

[0043] In the present invention, in the step (4), the sintering temperature is 1150-1200°C, preferably 1150°C, 1160°C, 1180°C, 1200°C, and the sintering time is 1-3h, preferably 1.5-2.5h, and more preferably 2h.

[0044] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0045] Example 1

[0046] Select a round iron rod 3-1 with a diameter of 1 mm, cut a 400-mesh wire mesh into a certain length, and then wrap it around the round iron rod 3-1 in three layers, and then fold and seal the bottom of the wire mesh to obtain a wire mesh main road mold (such as Figure 2 As shown), both ends of the round iron rod are higher than both ends of the wire mesh, which is convenient for taking out the round iron rod, and the wire mesh is a wire mesh woven in a plain weave manner with a pore size of 300 meshes.

[0047] Four magnetic sleeves 6-1 (the inner diameter of the magnetic sleeves 6-1 is 20.1 mm) are sleeved on the outer wall of the stainless steel tube shell 1 (the outer diameter of the stainless steel tube shell 1 is 20 mm, the wall thickness is 1 mm, and the length is 1500 mm), each magnetic sleeve has 3 positioning holes and 4 magnet embedding holes, three stainless steel cylindrical positioning rods 6-2 are passed through the positioning holes of the four magnetic sleeves 6-1, and the cylindrical magnet 6-3 is placed in the magnet embedding hole of the magnetic sleeve 6-1 (the above steps are as shown in FIG. Figure 3 and Figure 4 As shown), the wire mesh main channel mold is then placed in the stainless steel tube shell 1. Under the action of magnetic force, the wire mesh main channel mold is tightly adsorbed on the inner wall of the stainless steel tube shell 1, and the position of the wire mesh main channel mold corresponds to the position of the magnet 6-3 one by one (the above steps are as shown in FIG. Figure 5 shown).

[0048] Place the middle core rod 7-1 (the diameter of the middle core rod 7-1 is 13mm) in the compression spring 7-2 (the outer diameter of the compression spring 7-2 is 15mm, the inner diameter is 13.2mm and the length is 1510mm), and then place it in the center of the stainless steel tube shell 1, insert the stainless steel plug 8-1 at the bottom of the compression spring 7-2, the outer diameter of the plug 8-1 is consistent with the inner diameter of the stainless steel tube shell 1, and insert the plug 8-2 at the top of the stainless steel tube shell 1, wherein the plug 8-2 has a through hole 8-3, the outer diameter of the plug 8-2 is consistent with the inner diameter of the stainless steel tube shell 1, and the stainless steel metal powder can be filled into the gap between the stainless steel tube shell 1 and the tension spring 7-2 through the through hole 8-3 on the plug 8-2. During the filling process, it is necessary to continuously vibrate and compact. The stainless steel metal powder has an irregular morphology and a particle size between 100 and 200 meshes. When the stainless steel metal powder is filled to 1 cm from the top of the stainless steel tube shell 1, take out the round iron rod 3-1, remove the plug 8-2, fold and seal the excess wire mesh at the end, bury it in the stainless steel metal powder, continue to fill a small amount of stainless steel metal powder, so that the wire mesh is completely buried by the stainless steel metal powder, plug the plug 8-4 at the top of the stainless steel tube shell 1 to prevent the stainless steel metal powder from leaking out, and finally remove the magnetic suction sleeve 6-1 and take out the middle core rod 7-1 (the above steps are as follows Figure 6 , Figure 7 and Figure 8 As shown), then put it into a sintering furnace, raise the temperature of the sintering furnace to 1150°C, keep it at this temperature for 2 hours for sintering, remove the plugs 8-1 and 8-4 after sintering, and finally slowly pull out the tension spring 7-2.

[0049] Then, an end cap 4 is welded to the upper end of the stainless steel tube shell 1, and an end cap 5 with a liquid filling port is welded to the lower end of the stainless steel tube shell 1. After vacuuming through the end cap 5, protective argon gas is injected, and then liquid metal sodium working fluid is injected, and vacuuming is performed again. In order to further remove the internal non-condensable gas, the heat pipe is heated to 650°C while continuing to vacuumize. Finally, the liquid filling port is sealed by cold welding, and the liquid filling port is sealed again by argon arc welding to obtain a high-temperature heat pipe with a large aspect ratio of the main channel sintered liquid wick, wherein the porosity of the porous liquid wick is 68% (the above steps are as follows Fig. 9 shown).

[0050] Example 2

[0051] The difference from Example 1 is that the sintering temperature is 1200° C., the sintering time is 1 h, and the other conditions are the same.

[0052] Example 3

[0053] The difference from Example 1 is that the sintering temperature is 1180° C., the sintering time is 2 h, and the other conditions are the same.

[0054] It can be seen from the above embodiments that the present invention provides a high-temperature heat pipe with a large aspect ratio and a preparation method thereof. The high-temperature heat pipe of the present invention includes a tube shell, an end cover, a porous liquid absorbent core, a wire mesh trunk and a liquid metal working medium; the porous liquid absorbent core, the tube shell and the wire mesh trunk are sintered and formed as a whole. The present invention sinters the porous liquid absorbent core, the tube shell and the wire mesh trunk as a whole, which can reduce the contact thermal resistance, and the porous liquid absorbent core has a high capillary force and a large heat exchange area, and the wire mesh trunk has high permeability, which can significantly improve the heat transfer efficiency and heat transfer distance of the high-temperature heat pipe. When the preparation method provided by the present invention is used to prepare a high-temperature heat pipe with a large aspect ratio and a sintered liquid absorbent core, the middle core rod is easy to demold, and impurities such as a demolding agent that contaminates the liquid absorbent core are not introduced, which solves the problem of difficulty in demolding the high-temperature heat pipe, and can be used for the standardized and mass production of high-temperature heat pipes with dry-type liquid absorbent cores.

[0055] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A high-temperature heat pipe with a large aspect ratio and a sintered liquid-absorbing core, characterized in that: It comprises a tube shell, an end cover, a porous liquid absorbing core, a wire mesh main channel and a liquid metal working medium; the porous liquid absorbing core, the tube shell and the wire mesh main channel are integrally sintered and formed.

2. The high-temperature heat pipe with a large aspect ratio of main channel sintered liquid wick according to claim 1, characterized in that: The end covers are located at both ends of the tube shell; the porous liquid wick is attached to the inner wall of the tube shell.

3. The high-temperature heat pipe with a large aspect ratio of main channel sintered liquid wick according to claim 1 or 2, characterized in that: The porosity of the porous liquid-absorbing core is 40-80%.

4. The high-length-diameter-ratio main channel sintered liquid-absorbing core high-temperature heat pipe according to claim 3, characterized in that: The aperture of the wire mesh in the wire mesh main channel is 200-800 meshes, and the number of layers of the wire mesh is 2-4 layers.

5. The high-temperature heat pipe with a large aspect ratio of main channel sintered liquid wick according to claim 1, 2 or 4, characterized in that: The wire mesh trunk is located inside the porous liquid-absorbing core.

6. The method for preparing a high-temperature heat pipe with a large aspect ratio main channel sintered liquid wick according to any one of claims 1 to 5, characterized in that: The steps include: (1) Winding the wire mesh on a metal rod and fixing it to obtain a wire mesh main channel mold; (2) Insert the magnetic suction sleeve into the outer wall of the tube shell at intervals, and then place the wire mesh main channel mold in the tube shell, and adhere it to the inner wall of the tube shell under the action of magnetic force; (3) placing a core rod in a tension spring to obtain a core rod mold, and then placing the core rod mold in the center of the tube shell, filling the metal powder into the gap between the tube shell and the tension spring, and then sintering; (4) After sintering is completed, the tension spring is pulled out, and then the end covers are welded at both ends of the tube shell, and finally the liquid metal working medium is filled to obtain a high-temperature heat pipe with a large aspect ratio and a dry channel sintered liquid absorption core.

7. The method for preparing a high-temperature heat pipe with a large aspect ratio main channel sintered liquid wick according to claim 6, characterized in that: In the step (1), the diameter of the metal rod is 0.5 to 3 mm.

8. The method for preparing a high-temperature heat pipe with a large aspect ratio main channel sintered liquid wick according to claim 6 or 7, characterized in that: In the step (2), the magnetic sleeve has a positioning hole and a magnet embedding hole, wherein the positioning hole is used to place the positioning rod, and the magnet embedding hole is used to place the magnet; the magnet can magnetically attract the wire mesh main channel mold to the inner wall of the tube shell, and the positions of the magnet and the wire mesh main channel mold correspond one to one.

9. The method for preparing a high-temperature heat pipe with a large aspect ratio main channel sintered liquid wick according to claim 8, characterized in that: In the step (3), a plug is inserted into the bottom of the tension spring; the core rod mold is placed in the center of the tube shell, and the top of the tube shell is inserted into the plug, and a through hole is provided on the plug.

10. The method for preparing a high-temperature heat pipe with a large aspect ratio main channel sintered liquid wick according to claim 9, characterized in that: In the step (4), the sintering temperature is 1150-1200° C., and the sintering time is 1-3 hours.

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