Corrugated copper pipe for heat exchange

Abstract

The invention belongs to the technical field of heat exchange pipes, and discloses a corrugated copper pipe for heat exchange, which comprises a corrugated pipe base body, and the outer wall of the corrugated pipe base body is provided with a spiral pipe groove for a refrigerant to flow; the corrugated pipe further comprises a sheath arranged outside the corrugated pipe base body in a sleeving mode, and the sheath is fixedly connected with the peripheral side of the corrugated pipe base body. Capillary tubes are replaced by the tube grooves, so that the risk of refrigerant leakage is reduced, the heat exchange efficiency is greatly improved, and the practicability is high.

Description

Technical Field

[0001] The invention belongs to the technical field of heat exchange pipes, in particular to a corrugated copper pipe for heat exchange. Background Art

[0002] The heat exchange bellows is a key component of the heat pump water heater, mainly used in the carbon dioxide-water heat exchanger in the heat pump water heater to play a role in heat exchange. The structure of the heat exchange bellows commonly seen on the market is mainly to wrap three capillaries in the groove of the bellows, and then spot weld the connection between the bellows and the capillary to fix them.

[0003] Although the existing heat exchange bellows can play a role in heat exchange, there are still certain defects, mainly including:

[0004] 1. During the operation of the heat pump water heater, the carbon dioxide pressure in the capillary tube is at least 13MPa, and the spot welding area of ​​the capillary tube may have certain defects due to improper welding. In addition, the wall of the capillary tube is relatively thin, which greatly increases the risk of carbon dioxide leakage;

[0005] 2. The inner diameter of the capillary is small, which will restrict the flow rate of the capillary and greatly limit its heat exchange efficiency;

[0006] 3. The existing bellows mainly adopt a bare tube structure, and the inner and outer walls are both copper bare tubes. The heat exchange area is small and there is basically no disturbing effect on the fluid, which limits its heat exchange level. Summary of the invention

[0007] The purpose of the present invention is to provide a corrugated copper tube for heat exchange, which has a simple structure, adopts a tube groove instead of a capillary tube, reduces the risk of refrigerant leakage, greatly improves the heat exchange efficiency, and has strong practicality.

[0008] The technical solution adopted to achieve the purpose of the present invention is: a corrugated copper tube for heat exchange, including a bellows base, the outer wall of the bellows base is provided with a spiral pipe groove for the flow of refrigerant; it also includes a sheath arranged outside the bellows base, and the sheath is fixedly connected to the outer peripheral side of the bellows base.

[0009] Furthermore, the number of the pipe grooves is more than three, and the inlets and outlets of the pipe grooves are independent of each other.

[0010] Furthermore, an internal thread is provided inside the bellows base.

[0011] Furthermore, the thread teeth of the internal thread are shaped as special-shaped teeth with multiple layers of steps on both sides.

[0012] Furthermore, the height of the thread teeth is 0.05mm-6mm, the bottom wall thickness is 0.25mm-9mm, and the top angle is 25°-75°.

[0013] Furthermore, the number of the internal threads is 35-500 per cycle.

[0014] Furthermore, the wall thickness of the corrugated tube base is 0.3 mm-15 mm, and the diameter is 5 mm-80 mm.

[0015] Furthermore, the wall thickness of the sheath tube is 0.1 mm-2 mm, and the diameter is 5.05-80.2 mm.

[0016] The beneficial effects of the present invention are:

[0017] 1. The present invention abandons the traditional capillary tube and adopts a combination of a tube groove and a sheath, which saves materials and allows the refrigerant to directly contact the heat exchange pipe, further improving the heat exchange efficiency;

[0018] 2. The present invention forms a tube groove by spinning on the outer wall of the corrugated tube base, so that the whole body of the corrugated tube base presents a spiral corrugation. This structure can make the refrigerant continuously change suddenly when flowing to form a strong turbulence, thereby improving the heat transfer coefficient of the heat exchange tube, thereby greatly improving the heat exchange efficiency; in addition, the cross-section of the tube groove of the spiral structure is in an arc shape, so that its pressure bearing capacity is significantly improved, and this shape does not cause stress concentration, has small residual stress, and has uniform stress distribution;

[0019] 3. The internal thread of the present invention changes the morphology of the inner wall surface of the corrugated tube base, so that the heat exchange medium constantly collides with the internal thread and changes direction during the flow process, which increases the turbulence of the heat exchange medium, can better destroy the thermal boundary layer, reduce thermal resistance, and promote heat transfer; the setting of the internal thread also increases the effective heat transfer area in the corrugated tube base. Compared with a smooth straight tube, the internal thread provides a larger heat exchange area within the same length, thereby improving the heat transfer efficiency;

[0020] 4. The present invention sets the thread teeth as multi-layer stepped special-shaped teeth to increase the nucleation points of bubbles during the evaporation of the heat exchange medium and improve the evaporation heat exchange efficiency; and the steps on both sides of the thread teeth can more effectively disrupt the flow of the refrigerant and generate more turbulence and vortices; when the heat exchange medium passes through the step teeth, the steps can cause the flow direction of the heat exchange medium to change frequently, increasing the contact area and contact time between the heat exchange medium and the inner wall of the corrugated tube base, thereby greatly improving the heat exchange efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the present invention will be further described below in conjunction with the accompanying drawings and embodiments. 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 creative work:

[0022] Figure 1 It is a partial cross-sectional structural schematic diagram of the present invention.

[0023] Figure 2 It is a cross-sectional schematic diagram of the present invention.

[0024] Figure 3 It is a side view structural diagram of the bellows base body of the present invention when it is not spun.

[0025] Figure 4 yes Figure 3 An enlarged schematic diagram of a structure at A in the middle.

[0026] In the figure: 1. Bellows base; 2. Pipe groove; 3. Sheath; 4. Internal thread; 5. Thread teeth. DETAILED DESCRIPTION

[0027] The examples are provided to better illustrate the present invention, but the present invention is not limited to the examples. Therefore, those skilled in the art may make non-essential improvements and adjustments to the implementation scheme according to the above invention content, which still fall within the protection scope of the present invention.

[0028] like Figures 1 to 4 As shown, a corrugated copper tube for heat exchange includes a bellows base 1, the outer wall of which is provided with a spiral tube groove 2 for the flow of refrigerant; it also includes a sheath 3 which is sleeved on the outside of the bellows base 1, and the sheath 3 is fixedly connected to the outer peripheral side of the bellows base 1 (specifically, the wave crest of the longitudinal section of the bellows).

[0029] The corrugated copper tube of the present invention is used for common heat exchangers and water heater main pipes, wherein the corrugated tube base 1 is mainly used as a flow channel for the heat exchange medium, and the heat exchange medium is a common heat exchange medium such as water; the tube groove 2 is mainly used as a channel for the flow of the refrigerant, and the refrigerant is a common gas refrigerant such as carbon dioxide. The metal sheath 3 mainly plays the role of closing the outer periphery of the corrugated tube base 1, allowing the refrigerant fluid to flow only in a directional manner in the tube groove 2. The heat exchange medium flowing in the inner area of ​​the corrugated tube base 1 is a liquid such as water. Through the circulation of the gas refrigerant in the tube groove 2, the gas refrigerant continuously transfers the heat absorbed by the evaporator from the surrounding environment to the heat exchange medium in the corrugated tube base 1 to meet the heat exchange requirements. The present invention abandons the traditional capillary tube and adopts a combination of the tube groove 2 and the sheath 3. While saving materials, the refrigerant can be directly in contact with the heat exchange pipe, further improving the heat exchange efficiency.

[0030] The present invention forms a tube groove 2 by spinning on the outer wall of the corrugated tube base 1, so that the corrugated tube base 1 presents a spiral corrugated shape as a whole. This structure can make the refrigerant continuously change suddenly during the flow to form a strong turbulence, thereby improving the heat transfer coefficient of the heat exchange tube, thereby greatly improving the heat exchange efficiency; in addition, the cross-section of the tube groove 2 of the spiral structure is in an arc shape, so that its pressure bearing capacity is significantly improved, and this shape will not cause stress concentration, the residual stress is small, and the stress distribution is uniform.

[0031] The number of tube grooves 2 can be selected according to actual needs. To improve heat exchange efficiency, the present invention uses more than three tube grooves 2. In a preferred embodiment of the present invention, the number of tube grooves 2 is three, and the three tube grooves 2 are evenly arranged on the periphery of the corrugated tube base 1, and the overall distribution is a triple helical structure.

[0032] like Figure 3 and Figure 4 As shown, in the present invention, an internal thread 4 is provided inside the bellows base 1. According to the flow characteristics, turbulent flow has a higher heat transfer efficiency than laminar flow, and the internal thread 4 provided in the present invention changes the morphology of the inner wall surface of the bellows base 1, so that the heat exchange medium continuously collides with the internal thread 4 and changes direction during the flow process, thereby increasing the turbulence of the heat exchange medium, which can better destroy the thermal boundary layer, reduce thermal resistance, and promote heat transfer. The provision of the internal thread 4 also increases the effective heat transfer area in the bellows base 1. Compared with a smooth straight tube, the provision of the internal thread 4 provides a larger heat transfer area within the same length, thereby improving the heat transfer efficiency.

[0033] In order to further improve the heat transfer efficiency of the present invention, the present invention also sets the two sides of the thread teeth 5 of the internal thread 4 as multi-layer stepped special-shaped teeth. Setting the thread teeth 5 as multi-layer stepped special-shaped teeth can increase the nucleation points of bubbles during the evaporation of the heat exchange medium and improve the evaporation heat transfer efficiency. And the steps on both sides of the thread teeth 5 can more effectively disrupt the flow of the refrigerant and generate more turbulence and vortices. When the heat exchange medium passes through the step teeth, the steps can frequently change the flow direction of the heat exchange medium, increase the contact area and contact time between the heat exchange medium and the inner wall of the bellows matrix 1, thereby greatly improving the heat exchange efficiency. When the bellows matrix 1 flows and generates pressure, the double-sided steps can better disperse the pressure, reduce the situation where the local force of the thread teeth 5 is too large, and is conducive to improving the structural stability and service life of the thread teeth 5. In actual processing, the number of multi-layer steps on both sides of the thread teeth 5 can be more than one layer. In a preferred embodiment of the present invention, the number of steps on both sides of the thread teeth 5 is three layers.

[0034] The number of the internal threads 4 of the present invention is 35-500 per week, that is, the number of internal threads 4 in one cross section of the bellows base 1. The number of internal threads 4 has a relatively important influence on the heat conduction and heat exchange medium flow characteristics of the bellows, which is closely related to factors such as the disturbance degree of the heat exchange medium in the bellows base 1.

[0035] In the present invention,

[0036] The height of the thread teeth 5 is 0.05mm-6mm, the bottom wall thickness is 0.25mm-9mm, and the top angle is 25°-75°. In the present invention, the thread teeth 5 are made by the thread core head spinning method. The principle of the spinning method is to squeeze the core head with threads into the corrugated tube substrate 1, and the threads on the core head extrude the inner wall of the corrugated tube substrate 1 to form threads. The tooth height and bottom wall thickness of the thread teeth 5 are determined according to the diameter and pipe specifications of the mother tube of the corrugated tube substrate 1. Generally, the bottom wall thickness + tooth height = the wall thickness of the corrugated tube substrate 1. The height and bottom wall thickness of the thread teeth 5 selected in the present invention cover the common specifications and sizes of the internal thread copper tubes for air conditioners. If the sum of the tooth height and the bottom wall thickness is less than 0.30mm or greater than 15mm, it will not only exceed the existing processing capacity, but also be more inconsistent with the existing application scenarios. The tooth top angle of 25°-75° can not only ensure the strength of the entire thread teeth 5, but also increase its heat exchange efficiency. Specifically, if the tooth top angle is lower than 25°, the overall heat exchange area will be small, the fluid disturbance will be poor, and blockage will easily occur. If it is higher than 75°, the overall structural strength will be reduced and the fluid flow will be affected.

[0037] The wall thickness of the bellows base 1 is 0.3mm-15mm, and the diameter is 5mm-80mm. The above range is set according to daily use and needs, and is suitable for copper tubes for heat exchange (excluding capillaries, which have special specifications).

[0038] The wall thickness of the sheath 3 is 0.1mm-2mm, and the diameter is 5.05-80.2mm. The sheath 3 in the present invention is a pipe that is drawn after being sleeved on the top of the corrugated tube substrate 1, so the overall diameter of the sheath 3 needs to be slightly larger than the corrugated tube substrate 1 to ensure that the whole can be sleeved in. However, the diameter of the sheath 3 cannot be too large. If it is too large, relative sliding may occur during the subsequent drawing process. Therefore, in the present invention, the diameter of the sheath 3 is 0.05-0.2mm larger than the corrugated tube substrate 1, which can not only ensure that it can be sleeved on the corrugated tube substrate 1, but also prevent relative sliding during the subsequent drawing process. The wall of the sheath 3 only plays a role of protection and pressure resistance, so a thin-walled copper tube of 0.1-2mm can be selected, and the specific needs are selected according to the actual use conditions.

[0039] During the processing of the bellows of the present invention, the temperature of the diffusion-bonding heat treatment process is 600° C.-900° C., the pressure is 5 MPa-15 MPa, and the insulation time is 2 h-5 h.

[0040] When processing the structure of the present invention, firstly, the internal thread 4 is formed, then the pipe groove 2 is formed by spinning, and finally the sheath 3 is installed. The following is a brief introduction to the selection of various structural materials and processing methods in the present invention.

[0041] 1. Internal thread

[0042] The material of the bellows base 1 uses the existing copper plain tube, and the internal thread 4 is formed in the bellows base 1 mainly through different combinations of the outer mold and the core head, and is specifically prepared into a special-shaped tooth structure with better turbulence effect and higher heat exchange efficiency.

[0043] 2. Pipe Groove

[0044] In actual processing, a spiral corrugated tube processing method is used on the copper plain tube to form a spiral tube groove 2 on its surface. Specifically, a spiral corrugated tube with three groups of tube grooves 2 on the surface is produced by using a corrugated tube spinning machine and three groups of spinning cutter heads, which are fed through a feeding system, and the number of stretching circles of the tube grooves 2 on the corrugated tube is 5-40 circles, and the pressing depth is 2-20mm.

[0045] 3. Sheath

[0046] The selection of the material of the sheath 3 mainly considers strength and pressure resistance to ensure that it will not be broken down by the high-pressure working fluid. The specific material can be copper, stainless steel, titanium and other metals according to different working conditions. If the working environment is a general working condition, copper or stainless steel pipes can be used; if the working environment is a place with strong corrosion, more corrosion-resistant titanium pipes or other materials with good performance can be used. The sheath 3 of the present invention is actually a thin-walled tube sleeved on the outer wall of the corrugated tube base 1, and the two are fixed together by spinning and drawing.

[0047] In the above process, since the drawing process involves only the bonding between the solid phases, there will be gaps, which will lead to the failure to form an effective closure between the wave crest of the corrugated tube substrate 1 and the sheath 3 tube, thereby causing gas crossflow during the working process, resulting in air flow turbulence and affecting gas flow. Therefore, the present invention also uses diffusion bonding to combine the two together after spinning and drawing. Diffusion bonding is a common processing method in the field. Its principle is to make the atoms between the surfaces of two or more closely contacted materials diffuse with each other under certain temperature, pressure and time conditions, thereby forming a strong bonding process. During processing, it mainly relies on the thermal motion and concentration gradient of atoms to drive the atoms of different materials to penetrate and mix at the interface, and finally achieve metallurgical bonding. The assembled material is placed in a heating furnace by heating and heated to above the recrystallization temperature of the material to promote the diffusion of atoms. Keep it at the heating temperature for a certain time to allow the atoms to fully diffuse. After the insulation is completed, the material is cooled by air cooling and water cooling to obtain the desired performance. Diffusion bonding can achieve high-strength bonding: diffusion bonding can achieve high-strength bonding between materials, and its bonding strength is usually close to or reaches the strength of the parent material. The microstructure of the combined material is uniform and has no obvious interface defects. Therefore, the sheath 3 and the corrugated tube substrate 1 can be diffusely bonded at the wave crest position to seal them into a whole.

[0048] During the specific processing of the present invention, the sheath 3 is first set on the bellows substrate 1 by spinning and drawing, and then the temperature of the diffusion bonding heat treatment is set to 600-900°C, and then pressure is applied to make the atoms of the sheath 3 and the bellows substrate 1 at the wave crest bonding surface within the bonding distance, and appropriate pressure is provided to make it plastically flow to the abnormal gap area to be filled, so that the sheath 3 and the bellows substrate 1 are tightly combined at the wave crest to achieve a seamless state.

[0049] In order to further observe the appearance of the samples of the present invention and verify the pressure resistance of the corrugated pipe of the present invention, the present invention also designed Examples 1-3 and Comparative Examples 1-6.

[0050] Example 1

[0051] The process size adopted in this embodiment is relatively moderate. The structure of this embodiment is put into use, mainly for non-corrosive media and environments that require good heat exchange performance, specifically for common heat exchangers and water heater mains, and the temperature of the diffusion combined heat treatment process is 700°C, the pressure is 10MPa, the insulation time is 3h, and the cooling method adopts air cooling.

[0052] A corrugated copper tube for heat exchange comprises a corrugated tube base 1, on the outer wall of which are provided three spiral tube grooves 2 for the flow of refrigerant; and a sheath 3 sleeved on the outside of the corrugated tube base 1, and the sheath 3 is fixedly connected to the wave crest of the corrugated tube base 1. An internal thread 4 is provided inside the corrugated tube base 1, and the thread teeth 5 of the internal thread 4 are in the shape of multi-layer stepped special-shaped teeth on both sides. The parameters of each structure in the above-mentioned corrugated copper tube are as follows: the wall thickness of the corrugated tube base 1 is 0.8mm, and the outer diameter is 12mm; the thread tooth 5 of the internal thread 4 is 0.4mm high, the wall thickness of the tooth bottom is 0.4mm, the tooth top angle is 50°, and the number of internal threads 4 is 300 / week; the number of stretching circles of the corrugated tube is 25 circles, and the pressing claw depth of the tube groove 2 is 4mm; the sheath 3 is made of red copper plain tube with a wall thickness of 0.3mm and an inner diameter of 12.3mm. The outer diameter after sleeve pulling is 12mm.

[0053] Example 2

[0054] The process size specifications adopted in this embodiment are relatively large. The structure of this embodiment is put into use, mainly for non-corrosive media and environments that require good heat exchange performance, specifically for common heat exchangers and water heater mains, and the temperature of the diffusion combined heat treatment process is 700°C, the pressure is 10MPa, the insulation time is 3h, and the cooling method adopts air cooling.

[0055] A corrugated copper tube for heat exchange comprises a corrugated tube base 1, on the outer wall of which are provided three spiral tube grooves 2 for the flow of refrigerant; and a sheath 3 sleeved on the outside of the corrugated tube base 1, and the sheath 3 is fixedly connected to the wave crest of the corrugated tube base 1. An internal thread 4 is provided inside the corrugated tube base 1, and the thread teeth 5 of the internal thread 4 are in the shape of multi-layer stepped special-shaped teeth on both sides. The parameters of each structure in the above-mentioned corrugated copper tube are as follows: the wall thickness of the corrugated tube base 1 is 2mm, and the outer diameter is 28mm; the thread tooth 5 of the internal thread 4 is 0.9mm high, the wall thickness of the tooth bottom is 1.1mm, the tooth top angle is 60°, and the number of internal threads 4 is 450 / week; the number of stretching circles of the corrugated tube is 35 circles, and the pressing claw depth of the tube groove 2 is 12mm; the sheath 3 is made of red copper plain tube, with a wall thickness of 0.7mm, an inner diameter of 28.6mm, and an outer diameter of 28mm after sleeve drawing.

[0056] Example 3

[0057] The process size specification adopted in this embodiment is relatively small. The structure of this embodiment is put into use, mainly used in places where corrosive gas is diffused on the outside or corrosive liquid flows on the outside, such as heat exchange tubes used in petrochemical production or seawater ships, and the temperature of the diffusion combined heat treatment process is 800°C, the pressure is 10MPa, the insulation time is 4h, and the cooling method adopts air cooling.

[0058] A corrugated copper tube for heat exchange comprises a corrugated tube base 1, on the outer wall of which are provided three spiral tube grooves 2 for the flow of refrigerant; and a sheath 3 sleeved on the outside of the corrugated tube base 1, and the sheath 3 is fixedly connected to the wave crest of the corrugated tube base 1. An internal thread 4 is provided inside the corrugated tube base 1, and the thread teeth 5 of the internal thread 4 are in the shape of multi-layer stepped special-shaped teeth on both sides. The parameters of each structure in the above-mentioned corrugated copper tube are as follows: the wall thickness of the corrugated tube base 1 is 0.4mm, and the outer diameter is 8mm; the thread tooth 5 of the internal thread 4 is 0.15mm high, the wall thickness of the tooth bottom is 0.25mm, the tooth top angle is 35°, and the number of internal threads 4 is 100 / week; the number of stretching circles of the corrugated tube is 15 circles, and the pressing claw depth of the tube groove 2 is 3mm; the sheath 3 is made of smooth titanium tube with a wall thickness of 0.2mm and an inner diameter of 8.2mm. The outer diameter after sleeve drawing is 8mm.

[0059] Comparative Example 1

[0060] This embodiment uses copper tubes with smaller wall thickness and outer diameter. The structure of this embodiment is put into use, mainly for common heat exchangers and water heater main pipes. The temperature of the diffusion combined heat treatment process is 700°C, the pressure is 10MPa, the insulation time is 3h, and the cooling method is air cooling.

[0061] A corrugated copper tube for heat exchange includes a corrugated tube base 1, and the outer wall of the corrugated tube base 1 is provided with three spiral tube grooves 2 for the flow of refrigerant; it also includes a sheath 3 sleeved outside the corrugated tube base 1, and the sheath 3 is fixedly connected to the crest of the corrugated tube base 1. The inner part of the corrugated tube base 1 is provided with an internal thread 4, and the thread teeth 5 of the internal thread 4 are in the shape of multi-layer stepped special-shaped teeth on both sides. The parameters of each structure in the above-mentioned corrugated copper tube are as follows:

[0062] The wall thickness of the bellows base 1 is 0.2mm and the outer diameter is 4mm; the thread tooth 5 of the internal thread 4 is 0.1mm high, the wall thickness of the tooth bottom is 0.1mm, the tooth top angle is 35°, and the number of internal threads 4 is 30 per week; the number of stretching circles of the bellows is 10 circles, and the pressing claw depth of the pipe groove 2 is 2mm; the sheath 3 is made of smooth copper tube, with a wall thickness of 0.1mm, an inner diameter of 4.2mm, and an outer diameter of 4mm after pulling.

[0063] Comparative Example 2

[0064] Compared with Example 1, this embodiment is basically the same in structure, parameters, working environment and working parameters, and the main difference is that the diffusion combined heat treatment is increased to 1000° C. The process size adopted in this embodiment is relatively moderate, and the structure of this embodiment is put into use, mainly for non-corrosive media and environments that require good heat exchange performance, specifically for common heat exchangers and water heater mains, and the temperature of the diffusion combined heat treatment process is 1000° C., the pressure is 10MPa, the insulation time is 3h, and the cooling method adopts air cooling.

[0065] A corrugated copper tube for heat exchange comprises a corrugated tube base 1, on the outer wall of which are provided three spiral tube grooves 2 for the flow of refrigerant; and a sheath 3 sleeved on the outside of the corrugated tube base 1, and the sheath 3 is fixedly connected to the wave crest of the corrugated tube base 1. An internal thread 4 is provided inside the corrugated tube base 1, and the thread teeth 5 of the internal thread 4 are in the shape of multi-layer stepped special-shaped teeth on both sides. The parameters of each structure in the above-mentioned corrugated copper tube are as follows: the wall thickness of the corrugated tube base 1 is 0.8mm, and the outer diameter is 12mm; the thread tooth 5 of the internal thread 4 is 0.4mm high, the wall thickness of the tooth bottom is 0.4mm, the tooth top angle is 50°, and the number of internal threads 4 is 300 / week; the number of stretching circles of the corrugated tube is 25 circles, and the pressing claw depth of the tube groove 2 is 4mm; the sheath 3 is made of red copper plain tube with a wall thickness of 0.3mm and an inner diameter of 12.3mm. The outer diameter after sleeve pulling is 12mm.

[0066] Comparative Example 3

[0067] Compared with Example 1, the structure, parameters, working environment and working parameters of this embodiment are basically the same, and the main difference is that the holding time of the diffusion combined heat treatment is increased to 6 hours. The process size adopted in this embodiment is relatively moderate, and the structure of this embodiment is put into use, mainly for non-corrosive media and environments that require good heat exchange performance, specifically for common heat exchangers and water heater mains, and the temperature of the diffusion combined heat treatment process is 700°C, the pressure is 10MPa, the holding time is 6 hours, and the cooling method adopts air cooling.

[0068] A corrugated copper tube for heat exchange comprises a corrugated tube base 1, on the outer wall of which are provided three spiral tube grooves 2 for the flow of refrigerant; and a sheath 3 sleeved on the outside of the corrugated tube base 1, and the sheath 3 is fixedly connected to the wave crest of the corrugated tube base 1. An internal thread 4 is provided inside the corrugated tube base 1, and the thread teeth 5 of the internal thread 4 are in the shape of multi-layer stepped special-shaped teeth on both sides. The parameters of each structure in the above-mentioned corrugated copper tube are as follows: the wall thickness of the corrugated tube base 1 is 0.8mm, and the outer diameter is 12mm; the thread tooth 5 of the internal thread 4 is 0.4mm high, the wall thickness of the tooth bottom is 0.4mm, the tooth top angle is 50°, and the number of internal threads 4 is 300 / week; the number of stretching circles of the corrugated tube is 25 circles, and the pressing claw depth of the tube groove 2 is 4mm; the sheath 3 is made of red copper plain tube with a wall thickness of 0.3mm and an inner diameter of 12.3mm. The outer diameter after sleeve pulling is 12mm.

[0069] Comparative Example 4

[0070] Compared with Example 1, the structure, parameters, working environment and working parameters of this embodiment are basically the same, and the main difference is that the outer diameter of the sheath 3 is reduced to 11.4 mm after drawing. The process size adopted in this embodiment is relatively moderate, and the structure of this embodiment is put into use, mainly for non-corrosive media and environments that require good heat exchange performance, specifically for common heat exchangers and water heater mains, and the temperature of the diffusion combined heat treatment process is 700°C, the pressure is 10MPa, the insulation time is 6h, and the cooling method adopts air cooling.

[0071] A corrugated copper tube for heat exchange comprises a corrugated tube base 1, on the outer wall of which are provided three spiral tube grooves 2 for the flow of refrigerant; and a sheath 3 sleeved on the outside of the corrugated tube base 1, and the sheath 3 is fixedly connected to the wave crest of the corrugated tube base 1. An internal thread 4 is provided inside the corrugated tube base 1, and the thread teeth 5 of the internal thread 4 are in the shape of multi-layer stepped special-shaped teeth on both sides. The parameters of each structure in the above-mentioned corrugated copper tube are as follows: the wall thickness of the corrugated tube base 1 is 0.8mm, and the outer diameter is 12mm; the thread tooth 5 of the internal thread 4 is 0.4mm high, the wall thickness of the tooth bottom is 0.4mm, the tooth top angle is 50°, and the number of internal threads 4 is 300 / week; the number of stretching circles of the corrugated tube is 25 circles, and the pressing claw depth of the tube groove 2 is 4mm; the sheath 3 is made of red copper plain tube, with a wall thickness of 0.3mm, an inner diameter of 11.4mm, and an outer diameter of 12mm after sleeve drawing.

[0072] Comparative Example 5

[0073] Compared with Example 1, this embodiment is basically the same in structure, parameters, working environment and working parameters, and the main difference is that the temperature of the diffusion combined heat treatment process is reduced to 450° C. The process size adopted in this embodiment is relatively moderate, and the structure of this embodiment is put into use, mainly for non-corrosive media and environments that require good heat exchange performance, specifically for common heat exchangers and water heater mains, and the temperature of the diffusion combined heat treatment process is 450° C., the pressure is 10 MPa, the insulation time is 3 hours, and the cooling method adopts air cooling.

[0074] A corrugated copper tube for heat exchange comprises a corrugated tube base 1, on the outer wall of which are provided three spiral tube grooves 2 for the flow of refrigerant; and a sheath 3 sleeved on the outside of the corrugated tube base 1, and the sheath 3 is fixedly connected to the wave crest of the corrugated tube base 1. An internal thread 4 is provided inside the corrugated tube base 1, and the thread teeth 5 of the internal thread 4 are in the shape of multi-layer stepped special-shaped teeth on both sides. The parameters of each structure in the above-mentioned corrugated copper tube are as follows: the wall thickness of the corrugated tube base 1 is 0.8mm, and the outer diameter is 12mm; the thread tooth 5 of the internal thread 4 is 0.4mm high, the wall thickness of the tooth bottom is 0.4mm, the tooth top angle is 50°, and the number of internal threads 4 is 300 / week; the number of stretching circles of the corrugated tube is 25 circles, and the pressing claw depth of the tube groove 2 is 4mm; the sheath 3 is made of red copper plain tube with a wall thickness of 0.3mm and an inner diameter of 12.3mm. The outer diameter after sleeve pulling is 12mm.

[0075] Comparative Example 6

[0076] Compared with Example 1, this embodiment is basically the same in structure, parameters, working environment and working parameters, and the main difference is that a capillary is embedded in the pipe groove 2, and the refrigerant flows through the capillary. The process size adopted in this embodiment is relatively moderate, and the structure of this embodiment is put into use, mainly for non-corrosive media and environments that require good heat exchange performance, specifically for common heat exchangers and water heater mains, and the temperature of the diffusion combined heat treatment process is 450°C, the pressure is 10MPa, the insulation time is 3h, and the cooling method adopts air cooling.

[0077] A corrugated copper tube for heat exchange includes a corrugated tube base 1, on the outer wall of the corrugated tube base 1 are provided three spiral tube grooves 2 for the flow of refrigerant; a capillary tube is wound in the tube groove 2, the outer diameter of the wound capillary tube is 3.8 mm, and the wall thickness is 0.5 mm; and also includes a sheath 3 sleeved on the outside of the corrugated tube base 1, and the sheath 3 is fixedly connected to the wave crest of the corrugated tube base 1. The inside of the corrugated tube base 1 is provided with an internal thread 4, and the thread teeth 5 of the internal thread 4 are shaped as special-shaped teeth with multiple layers of steps on both sides. The parameters of each structure in the above-mentioned corrugated copper tube are as follows: the wall thickness of the corrugated tube base 1 is 0.8mm, and the outer diameter is 12mm; the thread tooth 5 of the internal thread 4 is 0.4mm high, the wall thickness of the tooth bottom is 0.4mm, the tooth top angle is 50°, and the number of internal threads 4 is 300 / week; the number of stretching circles of the corrugated tube is 25 circles, and the pressing claw depth of the tube groove 2 is 4mm; the sheath 3 is made of red copper plain tube with a wall thickness of 0.3mm and an inner diameter of 12.3mm. The outer diameter after sleeve pulling is 12mm.

[0078] The pipes of each embodiment were subjected to flow measurement and pressure resistance test, and after the work of each embodiment and comparative example was completed, the pipes were observed. The following is a brief description of the testing and observation process.

[0079] Appearance observation: The appearance is tested by visual observation without magnification; the wave crest and the junction area of ​​the sheath 3 tubes are observed by cutting the sample and observing it under a microscope with a magnification of 50 times.

[0080] Flow measurement: It is measured by turbine flowmeter, which has high measurement accuracy and fast response speed.

[0081] Pressure test: The pressure resistance performance is an extreme pressure test. Pressurize slowly and continuously, increase the pressure by 0.5MPa each time, maintain the pressure for 1min, observe whether the sample has no cracks or leakage (macroscopic deformation that does not cause leakage is allowed), and then continue to increase the pressure until leakage occurs.

[0082] The test and observation results are shown in Table 1 below.

[0083] Table 1 Comparison of test and observation results of Examples 1-3 and Comparative Examples 1-6

[0084]

[0085] According to the results in Table 1, the samples in Examples 1-3 of the present invention have good appearance, the wave crest and the sheath 3 tube are tightly connected without gaps, and it can be seen from Examples 1-2 and Comparative Examples 1-5 that the larger and medium-sized bellows have good flow and pressure resistance.

[0086] In the comparative examples, the copper tube of comparative example 1 is relatively thin, so its strength does not meet the minimum strength requirement for making the bellows, resulting in failure in the bellows manufacturing stage.

[0087] In Comparative Example 2, the high temperature of 1000° C. is close to the melting point of copper, resulting in partial melting of the copper tube under this high temperature and high pressure. After melting, the wall thickness of the sheath 3 is reduced, thereby reducing the pressure resistance performance.

[0088] The only difference between Comparative Example 3 and Example 1 is the insulation time. It can be seen that there is no obvious difference in the experimental results when the insulation time is 6 h or 3 h.

[0089] In comparative example 4, since the outer diameter after drawing is smaller than the size ratio of the corrugated tube base 1 and the sheath 3, the corrugated tube base 1 is protruded, and there is a protruding phenomenon in appearance.

[0090] Comparative Example 5 did not reach the appropriate heating temperature, resulting in the failure to form an effective metallurgical bonding interface between the corrugated tube base 1 and the sheath 3 tube, resulting in the existence of gaps. The gaps caused the gases in the three tube grooves 2 to invade each other, causing the gas flow to be disordered, interfere with each other, and reduce the directional flow.

[0091] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the present invention, which should be covered by the scope of the claims of the present invention.

Claims

1. A corrugated copper tube for heat exchange, characterized in that: The invention comprises a bellows base (1), wherein the outer wall of the bellows base (1) is provided with a spiral pipe groove (2) for the flow of refrigerant; and a sheath (3) sleeved on the outside of the bellows base (1), wherein the sheath (3) is fixedly connected to the outer peripheral side of the bellows base (1).

2. The corrugated copper tube for heat exchange according to claim 1, characterized in that: The number of the pipe grooves (2) is more than three, and the inlets and outlets of the pipe grooves (2) are independent of each other.

3. The corrugated copper tube for heat exchange according to claim 1 or 2, characterized in that: An internal thread (4) is provided inside the bellows base (1).

4. The corrugated copper tube for heat exchange according to claim 3, characterized in that: The thread teeth (5) of the internal thread (4) are shaped as special-shaped teeth with multiple layers of steps on both sides.

5. The corrugated copper tube for heat exchange according to claim 4, characterized in that: The height of the thread teeth (5) is 0.05mm-6mm, the bottom wall thickness is 0.25mm-9mm, and the top angle is 25°-75°.

6. The corrugated copper tube for heat exchange according to claim 4 or 5, characterized in that: The number of the internal threads (4) is 35-500 per cycle.

7. The corrugated copper tube for heat exchange according to claim 1, 2, 4 or 5, characterized in that: The wall thickness of the corrugated tube base (1) is 0.3 mm to 15 mm, and the diameter is 5 mm to 80 mm.

8. The corrugated copper tube for heat exchange according to claim 1, 2, 4 or 5, characterized in that: The wall thickness of the sheath (3) is 0.1mm-2mm, and the diameter is 5.05-80.2mm.

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