Countercurrent capillary microchannel heat exchanger and preparation method thereof

Abstract

The invention discloses a countercurrent capillary microchannel heat exchanger and a preparation method thereof, and relates to the technical field of heat exchangers. The heat exchanger comprises an upper sealing plate, a lower sealing plate and a capillary microchannel heat exchange part arranged between the upper sealing plate and the lower sealing plate; the capillary micro-channel heat exchange part comprises capillary straight flow channel layers and capillary bent flow channel layers which are stacked and alternately distributed, a partition plate is arranged between each capillary straight flow channel layer and the adjacent capillary bent flow channel layer, and each capillary straight flow channel layer comprises a plurality of straight capillary tubes which are tightly arranged; the capillary tube bending runner layer comprises a plurality of closely arranged bending capillary tubes; the straight capillary tube and the bent capillary tube are made of metal materials; the bent capillary tube is manufactured by bending a capillary tube after heat treatment, the hardness of the capillary tube after heat treatment is controlled to be within the Vickers hardness range from 250 to 400, and the bending speed during bending is within the range from 1 mm / s to 100 mm / s. Heat exchange between cold fluid and hot fluid can be greatly promoted, and the heat exchange efficiency is remarkably improved.

Description

Technical Field

[0001] The invention relates to the technical field of heat exchangers, and in particular to a countercurrent capillary microchannel heat exchanger and a preparation method thereof. Background Art

[0002] With the continuous advancement of modern industry and technology, heat exchangers have been widely used in many fields such as refrigeration and chemical industry. However, traditional heat exchangers have some defects, such as low heat transfer efficiency, large size, and uneven fluid distribution. With the growing demand for compactness and efficiency of heat exchangers, microchannel heat exchangers have emerged. Despite this, the existing microchannel heat exchangers still need to be further optimized in terms of design and manufacturing process, especially in achieving more efficient countercurrent heat exchange and improving overall performance. Summary of the invention

[0003] The purpose of the present invention is to provide a countercurrent capillary microchannel heat exchanger and a preparation method thereof, so as to solve the problems existing in the above-mentioned prior art, greatly promote the heat exchange between cold and hot fluids, and significantly improve the heat exchange efficiency.

[0004] To achieve the above object, the present invention provides the following solutions: The present invention provides a countercurrent capillary microchannel heat exchanger, comprising an upper sealing plate, a lower sealing plate and a capillary microchannel heat exchange portion arranged between the upper sealing plate and the lower sealing plate, a partition plate is respectively arranged between the capillary microchannel heat exchange portion and the upper sealing plate and the lower sealing plate, the capillary microchannel heat exchange portion comprises a capillary straight channel layer and a capillary curved channel layer which are stacked and alternately distributed, a partition plate is arranged between adjacent capillary straight channel layers and capillary curved channel layers, the capillary straight channel layer comprises a plurality of closely arranged straight capillaries, and the capillary curved channel layer comprises a plurality of closely arranged curved capillaries; the straight capillary and the curved capillary are made of metal, and the straight capillary and the curved capillary are heat exchanged in a countercurrent heat exchange manner; The bent capillary is obtained by bending after capillary heat treatment. The hardness of the capillary after heat treatment is controlled to be between 250 and 400 Vickers hardness. The bending speed during the bending process is between 1 mm / s and 100 mm / s.

[0005] In one embodiment, the outer diameters of the straight capillary and the curved capillary are between 0.5-5 mm.

[0006] In one embodiment, the straight capillary and the curved capillary are made of the same metal material.

[0007] In one embodiment, the straight capillary and the curved capillary are both made of stainless steel.

[0008] In one embodiment, the partition plate is made of the same material as the straight capillary tube.

[0009] In one embodiment, the capillary curved channel layer further includes two first positioning plates, each of the curved capillaries is disposed between the two first positioning plates, and the thickness of the first positioning plate is equal to the outer diameter of the curved capillary.

[0010] In one embodiment, the capillary straight channel layer further includes two second positioning plates, each of the straight capillaries is disposed between the two second positioning plates, and the thickness of the second positioning plate is equal to the outer diameter of the straight capillary.

[0011] The present invention also provides a method for preparing the countercurrent capillary microchannel heat exchanger described above, comprising the following steps: Step 1: Select the material, outer diameter and wall thickness of the capillary, and heat treat the capillary. After heat treatment, the hardness is controlled between 250 and 400 Vickers hardness; Step 2: cutting a capillary tube of a desired length to obtain the straight capillary tube; cutting a capillary tube of a desired length, bending the capillary tube to obtain the bent capillary tube, and during the bending process, controlling the bending speed to be between 1 mm / s and 100 mm / s; Step 3: Select a double mirror plate of the same material as the capillary tube and process it to obtain the partition; Step 4: repeatedly stacking the partition, the capillary bending channel layer and the capillary straight channel layer on the lower sealing plate in sequence, or repeatedly stacking the partition, the capillary straight channel layer and the capillary bending channel layer on the lower sealing plate in sequence; stacking another partition after reaching the required number of layers, and covering the upper sealing plate on the top; Step 5: The overall structure obtained in step 4 is subjected to vacuum diffusion welding. After welding, the heat exchanger performance test is performed. After the test is completed, the inlet and outlet headers are welded and connected, and the production is completed.

[0012] In one embodiment, when the capillary curved channel layer is stacked, the curved capillaries are positioned by first positioning plates on both sides; when the capillary straight channel layer is stacked, the straight capillaries are positioned by second positioning plates on both sides.

[0013] In one embodiment, in step 2, the capillary is bent by a bending die to obtain the bent capillary, and the dimensional accuracy of the bending die is controlled within ±0.01 mm, and the surface roughness is Ra0.8.

[0014] Compared with the prior art, the present invention has achieved the following technical effects: The countercurrent capillary microchannel heat exchanger and preparation method thereof provided by the present invention can effectively prolong the residence time of the fluid in the flow channel by setting a capillary curved flow channel layer, greatly promote the heat exchange between the cold and hot fluids, and significantly improve the heat exchange efficiency. The capillary hardness is between 250-400 in Vickers hardness. The capillary in this hardness range has good flexibility and processability, and is convenient for bending and forming various complex shapes to construct a unique flow channel structure to adapt to different spatial layouts and heat exchange requirements; the bending speed during the capillary bending process is between 1 mm / s and 100 mm / s, ensuring that the stress of the material of the capillary is evenly distributed during the bending process, preventing the increase of flow resistance due to microstructural defects inside the capillary caused by too fast or too slow speed, and ensuring the fluid heat exchange efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0016] Figure 1 Schematic diagram of the structure of a countercurrent capillary microchannel heat exchanger in an embodiment of the present invention; Figure 2 Schematic diagram of the structure of a Z-shaped curved capillary in an embodiment of the present invention; Figure 3 Schematic diagram of the structure of a wavy curved capillary in an embodiment of the present invention; Figure 4 It is a schematic diagram of the structure of a Z-wave composite curved capillary in an embodiment of the present invention.

[0017] In the figure: 1-upper sealing plate, 2-lower sealing plate, 3-capillary straight channel layer, 4-capillary curved channel layer, 5-partition plate, 6-straight capillary, 7-curved capillary, 8-first positioning plate, 9-second positioning plate. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] The purpose of the present invention is to provide a countercurrent capillary microchannel heat exchanger and a preparation method thereof, so as to solve the problems existing in the prior art, greatly promote the heat exchange between cold and hot fluids, and significantly improve the heat exchange efficiency.

[0020] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0021] Embodiment 1 like Figure 1-Figure 2 As shown, this embodiment provides a countercurrent capillary microchannel heat exchanger, comprising an upper sealing plate 1, a lower sealing plate 2 and a capillary microchannel heat exchange portion arranged between the upper sealing plate 1 and the lower sealing plate 2, a partition plate 5 is respectively provided between the capillary microchannel heat exchange portion and the upper sealing plate 1 and the lower sealing plate 2, the capillary microchannel heat exchange portion comprises stacked and alternately distributed capillary straight channel layers 3 and capillary curved channel layers 4, a partition plate 5 is provided between adjacent capillary straight channel layers 3 and capillary curved channel layers 4, the capillary straight channel layer 3 comprises a plurality of closely arranged straight capillaries 6, the capillary curved channel layer 4 comprises a plurality of closely arranged curved capillaries 7; the straight capillary 6 and the curved capillary 7 are made of metal, and the straight capillary 6 and the curved capillary 7 adopt a countercurrent heat exchange method for heat exchange; The bent capillary 7 is obtained by bending after capillary heat treatment. The hardness of the capillary after heat treatment is controlled to be between 250 and 400 Vickers hardness. The bending speed during the bending process is between 1 mm / s and 100 mm / s.

[0022] By setting the capillary bending channel layer 4, the residence time of the fluid in the channel can be effectively extended, which greatly promotes the heat exchange between the cold and hot fluids and significantly improves the heat exchange efficiency. The capillary hardness is between 250-400 Vickers hardness. The capillary within this hardness range has good flexibility and processability, which is convenient for bending and forming various complex shapes to construct a unique channel structure to adapt to different spatial layouts and heat exchange requirements; the bending speed during the capillary bending process is between 1 mm / s and 100 mm / s to ensure that the stress of the capillary material is evenly distributed during the bending process, to prevent the microstructural defects inside the capillary from increasing the flow resistance due to too fast or too slow speed, and to ensure the fluid heat exchange efficiency.

[0023] The bent capillary tube 7 in this embodiment is a Z-shaped structure formed by bending a whole capillary tube. This structure makes the flow path of the fluid in the flow channel present a continuous Z-shape, which prolongs the residence time of the fluid in the flow channel. The bent capillary tube 7 is formed by bending a whole capillary tube, which effectively reduces the connection parts, reduces the leakage risk and fluid resistance that may be caused by the connection points, ensures the stability and efficiency of the heat exchanger operation, and is relatively simple in manufacturing process, which is conducive to large-scale production and cost control.

[0024] The bending form of the bent capillary tube 7 can be changed according to the actual use situation to achieve better heat exchange efficiency. For example, the bending form of the bent capillary tube 7 can also be set to a wave shape ( Figure 3 Shown), Z-wave composite type ( Figure 4 shown) etc.

[0025] The heat exchanger provided in this embodiment is a countercurrent type, such as Figure 1 As shown, the inlet and outlet of the capillary curved channel layer 4 are on the left and right sides, and the inlet and outlet of the capillary straight channel layer 3 are on the upper and lower sides, forming a countercurrent heat exchanger. The countercurrent heat exchange principle is fully utilized to ensure that the hot fluid and the cold fluid always maintain a large temperature difference driving force in the heat exchanger, significantly enhancing the power of heat transfer, thereby greatly improving the heat exchange efficiency. At the same time, the differentiated design of the inlet and outlet of different channel layers effectively optimizes the uniformity of fluid distribution inside the heat exchanger, reduces local thermal stress concentration and the occurrence of fluid dead zones, further improves the overall stability and reliability of the heat exchanger, extends its service life, and can better adapt to the heat exchange requirements under various complex working conditions.

[0026] The outer diameter of the straight capillary 6 and the curved capillary 7 is between 0.5 and 5 mm. A smaller outer diameter can greatly increase the number of capillaries per unit volume, thereby significantly improving the heat exchange area density and enhancing the heat exchange effect. It is suitable for different space layouts and heat exchange requirements.

[0027] The straight capillary 6 and the curved capillary 7 are made of the same metal material, and in this embodiment, both are made of stainless steel. The partition plate 5 is made of the same material as the straight capillary 6, also made of stainless steel.

[0028] In this embodiment, the capillary bending channel layer 4 further includes two first positioning plates 8, each of the bent capillaries 7 is disposed between the two first positioning plates 8, and the thickness of the first positioning plate 8 is equal to the outer diameter of the bent capillary 7. The first positioning plates 8 are used to position the bent capillary 7 and provide support to prevent the bent capillary 7 from being deformed by pressure.

[0029] In this embodiment, the capillary straight channel layer 3 further includes two second positioning plates 9, and each straight capillary 6 is arranged between the two second positioning plates 9. The thickness of the second positioning plate 9 is equal to the outer diameter of the straight capillary 6. The second positioning plates 9 are used to position the straight capillary 6 and play a supporting role to prevent the straight capillary 6 from being compressed and deformed.

[0030] Embodiment 2 This embodiment provides a method for preparing the countercurrent capillary microchannel heat exchanger described in Embodiment 1, comprising the following steps: Step 1: Select the capillary material (stainless steel), outer diameter and wall thickness, and heat treat the capillary. The hardness after heat treatment is controlled between 250 and 400 Vickers hardness. Heat treatment can avoid plastic deformation of the capillary when bending. When selecting the wall thickness, determine the wall thickness according to the temperature, pressure and corrosion conditions of the actual working conditions. Step 2: cutting a capillary tube of a desired length to obtain a straight capillary tube 6; cutting a capillary tube of a desired length, bending the capillary tube to obtain a bent capillary tube 7, and during the bending process, controlling the bending speed to be between 1 mm / s and 100 mm / s; Step 3: Select a double mirror plate of the same material as the capillary tube and process it to obtain a partition 5; Step 4: repeatedly stacking the partition plate 5, the capillary curved channel layer 4 and the capillary straight channel layer 3 on the lower sealing plate 2, or repeatedly stacking the partition plate 5, the capillary straight channel layer 3 and the capillary curved channel layer 4 on the lower sealing plate 2; stacking another partition plate 5 after reaching the required number of layers, and covering the upper sealing plate 1 on the top; Step 5: Vacuum diffusion weld the whole structure obtained in step 4, and perform a heat exchanger performance test after welding. After the test, perform argon arc welding or electric arc welding on each inlet and outlet header and take over the pipes, and the production is completed. The medium first enters the header and then enters each layer of the channel.

[0031] When stacking the capillary curved channel layer 4, the curved capillary 7 is positioned by the first positioning plates on both sides; when stacking the capillary straight channel layer 3, the straight capillary 6 is positioned by the second positioning plates 9 on both sides.

[0032] In step 1, the heat treatment of the stainless steel capillary includes: Place the capillary in an annealing furnace and heat it to 1050-1100 degrees Celsius for a sufficient time to release the stress inside the material, recrystallize the grain boundaries, clarify the grain boundaries, and obtain a certain degree of grain coarsening to improve the plasticity of the metal. Then quickly cool it to about 350 degrees Celsius and control the hardness between 250-400 Vickers hardness.

[0033] In step 2, the capillary is bent by a bending die to obtain a bent capillary 7. When the capillary is bent, the bending part is very likely to produce dimensional deformation, so the dimensional tolerance of the bending die used when bending the capillary is consistent with the outer diameter tolerance of the capillary, and the tolerance range is ±0.01mm. According to the size, shape and bending requirements of the capillary, the corresponding bending die is made. The dimensional accuracy of the bending die should be controlled within ±0.01mm, and the surface roughness should be Ra0.8 to reduce damage to the capillary surface. During the bending process, the bending speed is controlled between 1 mm / s and 100 mm / s to ensure that the stress of the capillary material is evenly distributed during the bending process to prevent the internal microstructure defects of the capillary from increasing the flow resistance due to too fast or too slow speed.

[0034] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A countercurrent capillary microchannel heat exchanger, characterized in that: It comprises an upper sealing plate, a lower sealing plate and a capillary microchannel heat exchange part arranged between the upper sealing plate and the lower sealing plate, a partition is respectively arranged between the capillary microchannel heat exchange part and the upper sealing plate and the lower sealing plate, the capillary microchannel heat exchange part comprises a capillary straight channel layer and a capillary curved channel layer which are stacked and alternately distributed, a partition is arranged between adjacent capillary straight channel layers and capillary curved channel layers, the capillary straight channel layer comprises a plurality of closely arranged straight capillaries, and the capillary curved channel layer comprises a plurality of closely arranged curved capillaries; the straight capillary and the curved capillary are made of metal, and the straight capillary and the curved capillary are heat exchanged in a countercurrent heat exchange manner; The bent capillary is obtained by bending after capillary heat treatment. The hardness of the capillary after heat treatment is controlled to be between 250 and 400 Vickers hardness. The bending speed during the bending process is between 1 mm / s and 100 mm / s.

2. The countercurrent capillary microchannel heat exchanger according to claim 1, characterized in that: The outer diameters of the straight capillary and the curved capillary are between 0.5 and 5 mm.

3. The countercurrent capillary microchannel heat exchanger according to claim 1, characterized in that: The straight capillary and the curved capillary are made of the same metal material.

4. The countercurrent capillary microchannel heat exchanger according to claim 3, characterized in that: The straight capillary and the curved capillary are both made of stainless steel.

5. The countercurrent capillary microchannel heat exchanger according to claim 3, characterized in that: The partition plate is made of the same material as the straight capillary tube.

6. The countercurrent capillary microchannel heat exchanger according to claim 1, characterized in that: The capillary curved channel layer further includes two first positioning plates, each of the curved capillaries is arranged between the two first positioning plates, and the thickness of the first positioning plate is equal to the outer diameter of the curved capillary.

7. The countercurrent capillary microchannel heat exchanger according to claim 1, characterized in that: The capillary straight channel layer further includes two second positioning plates, each of the straight capillaries is disposed between the two second positioning plates, and the thickness of the second positioning plate is equal to the outer diameter of the straight capillary.

8. A method for preparing a countercurrent capillary microchannel heat exchanger according to any one of claims 1 to 7, characterized in that: The following steps are involved: Step 1: Select the material, outer diameter and wall thickness of the capillary, and heat treat the capillary. After heat treatment, the hardness is controlled between 250 and 400 Vickers hardness; Step 2: cutting a capillary tube of a desired length to obtain the straight capillary tube; cutting a capillary tube of a desired length, bending the capillary tube to obtain the bent capillary tube, and during the bending process, controlling the bending speed to be between 1 mm / s and 100 mm / s; Step 3: Select a double mirror plate of the same material as the capillary tube and process it to obtain the partition; Step 4: repeatedly stacking the partition, the capillary bending channel layer and the capillary straight channel layer on the lower sealing plate in sequence, or repeatedly stacking the partition, the capillary straight channel layer and the capillary bending channel layer on the lower sealing plate in sequence; stacking another partition after reaching the required number of layers, and covering the upper sealing plate on the top; Step 5: The overall structure obtained in step 4 is subjected to vacuum diffusion welding. After welding, the heat exchanger performance test is performed. After the test is completed, the inlet and outlet headers are welded and connected, and the production is completed.

9. The method for preparing a countercurrent capillary microchannel heat exchanger according to claim 8, characterized in that: When the capillary curved channel layer is stacked, the curved capillary is positioned by the first positioning plates on both sides; when the capillary straight channel layer is stacked, the straight capillary is positioned by the second positioning plates on both sides.

10. The method for preparing a countercurrent capillary microchannel heat exchanger according to claim 8, characterized in that: In step 2, the capillary is bent by a bending die to obtain the bent capillary, the dimensional accuracy of the bending die is controlled within ±0.01 mm, and the surface roughness is Ra0.8.

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