Corrugated copper pipe for heat exchange

Abstract

The utility model 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 a spiral pipe groove for refrigerant to flow is arranged on the outer wall of the corrugated pipe base body. 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 utility model belongs to heat exchange pipe technical field, specifically a kind of corrugated copper pipe for heat exchange. BACKGROUND

[0002] Heat exchange corrugated pipe is the key component of heat pump water heater, mainly used in carbon dioxide-water heat exchanger in heat pump water heater, to play the role of heat exchange.The structure of the common heat exchange corrugated pipe on the market is mainly that three capillary tubes are wound in the groove of corrugated pipe, then spot welding is used to weld and fix at the connection of corrugated pipe and capillary tube.

[0003] Although the existing heat exchange corrugated pipe can play the role of heat exchange, but there are still certain defects, mainly including:

[0004] 1, in the working process of heat pump water heater, the carbon dioxide pressure in capillary tube is at least 13MPa, and the spot welding area of capillary tube may exist certain defects due to improper welding, and the wall of capillary tube is relatively thin, greatly increasing the risk of carbon dioxide leakage;

[0005] 2, the inner diameter of capillary tube is small, which will cause the flow of capillary tube to be restricted, greatly limiting its heat exchange efficiency;

[0006] 3, the existing corrugated pipe mainly adopts light pipe structure, and the inner and outer walls of copper pipe are light pipe, the heat exchange area is small and the fluid is basically not disturbed, which limits the heat exchange level. INVENTION CONTENTS

[0007] The utility model aims at providing a kind of corrugated copper pipe for heat exchange, its structure is simple, adopts pipe groove instead of capillary tube, reduces the risk of refrigerant leakage, and greatly improves heat exchange efficiency, and practicality is strong.

[0008] The technical scheme adopted to realize the utility model aims at providing a kind of corrugated copper pipe for heat exchange, including the base body for corrugated pipe, spiral pipe groove for the flow of refrigerant is equipped on the outer wall of corrugated pipe base body;It further includes the sheath that is sheathed in the outer corrugated pipe base body, and the periphery of sheath and corrugated pipe base body is fixedly connected.

[0009] Further, the number of pipe grooves is more than three, and the inlet and outlet of pipe groove are mutually independent.

[0010] Further, the inner thread is provided in the corrugated pipe base body.

[0011] Further, the thread tooth shape of inner thread is profiled tooth with multilayer ladder shape on both sides.

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

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

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

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

[0016] The beneficial effects of this utility model are as follows:

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

[0018] 2. This utility model spins a groove on the outer wall of the corrugated pipe base, making the corrugated pipe base present a spiral corrugated shape. This structure allows the refrigerant to continuously change abruptly and form strong turbulence during flow, which improves the heat transfer coefficient of the heat exchange tube and thus greatly improves the heat exchange efficiency. In addition, the cross-section of the spiral structure groove is arc-shaped, which significantly improves its pressure bearing capacity. Moreover, this shape will not cause stress concentration, has low residual stress, and uniform stress distribution.

[0019] 3. The internal thread of this utility model changes the morphology of the inner wall of the bellows base, causing the heat exchange medium to continuously collide with and change direction with the internal thread during the flow process, increasing the turbulence of the heat exchange medium, which can better disrupt 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 bellows base. Compared with a smooth straight pipe, the internal thread provides a larger heat transfer area within the same length, thereby improving the heat transfer efficiency.

[0020] 4. The present invention uses multi-layered stepped irregular teeth to increase the nucleation points of bubbles during the evaporation of the heat exchange medium, thereby improving the evaporation heat exchange efficiency. Furthermore, the steps on both sides of the thread teeth can more effectively disrupt the flow of the refrigerant, generating more turbulence and vortices. When the heat exchange medium passes through the stepped 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 bellows base, thereby greatly improving the heat exchange efficiency. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the utility model will be further described below in conjunction with the accompanying drawings and embodiments. The drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a partial cross-sectional structural schematic diagram of this utility model.

[0023] Figure 2 This is a cross-sectional schematic diagram of this utility model.

[0024] Figure 3 This is a side view of the structure of the corrugated pipe substrate when it is not spun in this utility model.

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

[0026] In the figure: 1. Corrugated pipe base; 2. Pipe groove; 3. Sheath; 4. Internal thread; 5. Thread teeth. Detailed Implementation

[0027] The illustrated embodiments are provided to better illustrate the present invention, but the content of the present invention is not limited to the illustrated embodiments. Therefore, non-essential improvements and adjustments made to the implementation schemes by those skilled in the art based on the above-described content of the present invention 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 corrugated tube base 1, with a spiral groove 2 on the outer wall of the corrugated tube base 1 for the flow of refrigerant; it also includes a sheath 3 sleeved on the outside of the corrugated tube base 1, and the sheath 3 is fixedly connected to the outer periphery of the corrugated tube base 1 (specifically at the crest of the longitudinal section of the corrugated tube).

[0029] This invention relates to a corrugated copper tube used in common heat exchangers and water heater main pipes. The corrugated tube base 1 primarily serves as the flow channel for the heat exchange medium, such as water. The tube groove 2 primarily serves as the flow channel for the refrigerant, such as carbon dioxide. The metal sheath 3 mainly functions to seal the outer periphery of the corrugated tube base 1, allowing the refrigerant fluid to flow only in the tube groove 2. The heat exchange medium flowing inside the corrugated tube base 1 is a liquid such as water. Through the circulation of the gaseous refrigerant within the tube groove 2, the gaseous refrigerant continuously transfers the heat absorbed by the evaporator from the surrounding environment to the heat exchange medium in the corrugated tube base 1, thus achieving the required heat exchange. This invention abandons the traditional capillary tube, employing a combination of the tube groove 2 and the sheath 3. This saves materials and allows the refrigerant to directly contact the heat exchange pipe, further improving heat exchange efficiency.

[0030] This invention spins a groove 2 on the outer wall of the corrugated pipe base 1, making the corrugated pipe base 1 present a spiral corrugated shape. This structure allows the refrigerant to continuously change abruptly and form strong turbulence during flow, which improves the heat transfer coefficient of the heat exchange tube and thus greatly improves the heat exchange efficiency. In addition, the cross-section of the spiral groove 2 is arc-shaped, which significantly improves its pressure bearing capacity. Moreover, this shape will not cause stress concentration, has low residual stress, and uniform stress distribution.

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

[0032] like Figure 3 and Figure 4 As shown, in this invention, the corrugated pipe base 1 has an internal thread 4. According to flow characteristics, turbulent flow has higher heat transfer efficiency than laminar flow. The internal thread 4 in this invention alters the morphology of the inner wall of the corrugated pipe base 1, causing the heat transfer medium to continuously collide with and change direction against the internal thread 4 during flow, thereby increasing the turbulence of the heat transfer medium. This better disrupts the thermal boundary layer, reduces thermal resistance, and promotes heat transfer. The internal thread 4 also increases the effective heat transfer area within the corrugated pipe base 1. Compared to a smooth straight pipe, the internal thread 4 provides a larger heat transfer area over the same length, thus improving heat transfer efficiency.

[0033] To further improve the heat transfer efficiency of this invention, the internal thread 4 is further configured with multi-layered stepped irregular teeth on both sides of the thread teeth 5. Setting the thread teeth 5 as multi-layered stepped irregular teeth increases the nucleation points of bubbles during the evaporation of the heat exchange medium, thereby improving the evaporation heat transfer efficiency. Furthermore, the steps on both sides of the thread teeth 5 can more effectively disrupt the flow of the refrigerant, generating more turbulence and vortices. When the heat exchange medium passes through the stepped teeth, the steps 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 bellows base 1, thus greatly improving the heat transfer efficiency. When pressure is generated by the flow in the bellows base 1, the double-sided steps can better disperse the pressure, reducing the excessive local stress on the thread teeth 5, which is beneficial to improving the structural stability and service life of the thread teeth 5. In actual processing, the number of multi-layered steps on both sides of the thread teeth 5 can be more than one layer. In a preferred embodiment of this invention, the number of stepped layers on both sides of the thread teeth 5 is three.

[0034] The number of internal threads 4 in this invention is 35-500 per cycle, 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 significant impact on the heat conduction and heat exchange medium flow characteristics of the bellows, and is closely related to factors such as the degree of disturbance of the heat exchange medium in the bellows base 1.

[0035] In this utility model,

[0036] The thread tooth 5 has a height of 0.05mm-6mm, a bottom wall thickness of 0.25mm-9mm, and a apex angle of 25°-75°. In this invention, the thread tooth 5 is manufactured using a threaded mandrel spinning method. The principle of this method is to insert a threaded mandrel into the bellows base 1, where the threads on the mandrel compress the inner wall of the bellows base 1 to form threads. The tooth height and bottom wall thickness of the thread tooth 5 are determined based on the pipe diameter and specifications of the bellows base 1. Generally, bottom wall thickness + tooth height = bellows base 1 wall thickness. The selected thread tooth 5 height and bottom wall thickness in this invention cover common specifications and dimensions of internally threaded copper pipes used in air conditioning. If the sum of the tooth height and bottom wall thickness is less than 0.30mm or greater than 15mm, it would not only exceed existing processing capabilities but also be unsuitable for current application scenarios. A tooth apex angle of 25°-75° not only ensures the overall strength of the thread tooth 5 but also increases its heat exchange efficiency. Specifically, if the tooth tip angle is less than 25°, it will result in a small overall heat exchange area, poor fluid turbulence, and easy blockage. If it is greater than 75°, it will reduce the overall structural strength and affect fluid flow.

[0037] The wall thickness of the corrugated tube 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 applicable to copper tubes for heat exchange (excluding capillary tubes, which have special specifications).

[0038] The sheath 3 has a wall thickness of 0.1mm-2mm and a diameter of 5.05-80.2mm. In this invention, the sheath 3 is a tube that is fitted over the corrugated pipe base 1 before being drawn. Therefore, the overall diameter of the sheath 3 needs to be slightly larger than that of the corrugated pipe base 1 to ensure that it can be fitted. However, the diameter of the sheath 3 cannot be too large, as this may cause relative slippage during the subsequent drawing process. Therefore, in this invention, the diameter of the sheath 3 is 0.05-0.2mm larger than that of the corrugated pipe base 1, which ensures that it can be fitted onto the corrugated pipe base 1 while preventing relative slippage during the subsequent drawing process. The wall of the sheath 3 only serves a protective and pressure-resistant function; therefore, a thin-walled copper tube of 0.1-2mm is sufficient, depending on the actual operating conditions.

[0039] In the processing of the corrugated pipe of this utility model, the temperature of the diffusion bonding heat treatment process is 600℃-900℃, the pressure is 5MPa-15MPa, and the heat preservation time is 2h-5h.

[0040] In the manufacturing process of this utility model, the internal thread 4 is first formed, then the tube groove 2 is formed by spinning, and finally the protective sleeve 3 is fitted. The following is a brief introduction to the selection of materials and processing methods for each structure in this utility model.

[0041] I. Internal Thread

[0042] The material of the bellows base 1 is the existing copper tube. The internal threads 4 are formed in the bellows base 1 by different combinations of the outer mold and the core head. Specifically, it is made into a special tooth structure with better turbulence effect and higher heat exchange efficiency.

[0043] II. Pipeline

[0044] In actual processing, a spiral groove 2 is formed on the surface of the copper tube using a spiral corrugated tube processing method. Specifically, a corrugated tube spinning machine is used, with three sets of spinning cutters fed by a feeding system to produce a spiral corrugated tube with three sets of grooves 2 on the surface. The number of stretching turns of the grooves 2 on the corrugated tube is 5-40 turns, and the pressing depth is 2-20mm.

[0045] III. Sheath

[0046] The selection of the material for the sheath 3 tube mainly considers strength and pressure resistance to ensure that it will not be punctured by high-pressure working fluids. Specific materials can be copper, stainless steel, titanium, or other metals depending on the operating conditions. For general operating environments, copper or stainless steel tubes can be used; for highly corrosive environments, more corrosion-resistant titanium tubes or other materials with good performance can be used. The sheath 3 of this invention is actually a thin-walled tube fitted onto the outer wall of the corrugated pipe base 1, and the two are fixedly joined together by spinning and drawing.

[0047] In the above process, since the drawing process only involves the bonding between solid phases, gaps will exist. This will prevent an effective seal from forming between the corrugated pipe base 1 and the sheath 3, causing gas leakage and turbulent airflow during operation. Therefore, this invention combines spinning and drawing with diffusion bonding to bond the two together. Diffusion bonding is a common processing method in the field. Its principle is that under certain temperature, pressure, and time conditions, atoms between two or more closely contacting material surfaces diffuse into each other, forming a strong bond. During processing, it mainly relies on the thermal motion and concentration gradient of atoms to drive the interpenetration and mixing of atoms from different materials at the interface, ultimately achieving metallurgical bonding. The assembled material is placed in a heating furnace and heated to above the recrystallization temperature of the material to promote atomic diffusion. The heating temperature is maintained for a certain time to allow sufficient atomic diffusion. After the holding period, the material is cooled by air cooling and water cooling to obtain the required properties. 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 combined material has a uniform microstructure and no obvious interface defects. Therefore, diffusion bonding can be used to form a diffusion bond at the crest positions of the sheath 3 and the corrugated pipe substrate 1, sealing them into a whole.

[0048] In the specific processing of this utility model, the sheath 3 is first set on the corrugated pipe base 1 by spinning and drawing. Then, the temperature of the diffusion bonding heat treatment is set to 600-900℃. Then, pressure is applied to make the atoms of the sheath 3 and the corrugated pipe base 1 within the bonding distance at the peak bonding surface. Appropriate pressure is provided to make it plastically flow to the abnormal void area that needs to be filled, so that the sheath 3 and the corrugated pipe base 1 are tightly bonded at the peak, achieving a seamless state.

[0049] To further observe the appearance of the samples of this utility model and verify the pressure resistance of the new corrugated pipe, this utility model also includes Examples 1-3 and Comparative Examples 1-6.

[0050] Example 1

[0051] The process dimensions used in this embodiment are relatively moderate. The structure of this embodiment is primarily intended for use in environments and media requiring good heat exchange performance, such as non-corrosive media. Specifically, it is used in common heat exchangers and water heater main pipes. The diffusion-combined heat treatment process involves a temperature of 700℃, a pressure of 10MPa, a holding time of 3 hours, and air cooling.

[0052] A corrugated copper tube for heat exchange includes a corrugated tube base 1, with three spiral grooves 2 on the outer wall of the corrugated tube base 1 for refrigerant flow; it also includes a sheath 3 fitted over the corrugated tube base 1, and the sheath 3 is fixedly connected to the crest of the corrugated tube base 1. The corrugated tube base 1 has an internal thread 4 inside, and the thread teeth 5 of the internal thread 4 are irregularly shaped with multiple stepped teeth on both sides. The specific 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 height of the internal thread 4 is 0.4mm, the tooth root wall thickness is 0.4mm, the tooth tip angle is 50°, and the number of internal threads 4 is 300 per turn; the number of corrugated tube stretching turns is 25 turns, and the depth of the pressure claw of the tube groove 2 is 4mm; the sheath 3 is made of pure copper tube, with a wall thickness of 0.3mm, an inner diameter of 12.3mm, and an outer diameter of 12mm after being pulled.

[0053] Example 2

[0054] The process dimensions used in this embodiment are relatively large. The structure of this embodiment is mainly used in non-corrosive media and environments that require good heat exchange performance, specifically in common heat exchangers and water heater main pipes. The diffusion-combined heat treatment process has a temperature of 700℃, a pressure of 10MPa, a heat preservation time of 3h, and uses air cooling.

[0055] A corrugated copper tube for heat exchange includes a corrugated tube base 1, with three spiral grooves 2 on the outer wall of the corrugated tube base 1 for refrigerant flow; it also includes a sheath 3 fitted over the corrugated tube base 1, and the sheath 3 is fixedly connected to the crest of the corrugated tube base 1. The corrugated tube base 1 has an internal thread 4 inside, and the thread teeth 5 of the internal thread 4 are irregularly shaped with multiple stepped teeth on both sides. The specific 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 height of the internal thread 4 is 0.9mm, the tooth root wall thickness is 1.1mm, the tooth tip angle is 60°, and the number of internal threads 4 is 450 per turn; the number of corrugated tube stretching turns is 35 turns, and the depth of the clamping claw of the tube groove 2 is 12mm; the sheath 3 is made of pure copper tube, with a wall thickness of 0.7mm, an inner diameter of 28.6mm, and an outer diameter of 28mm after being pulled.

[0056] Example 3

[0057] The process dimensions used in this embodiment are relatively small. The structure of this embodiment is primarily intended for use in locations where corrosive gases diffuse on the outside or corrosive liquids flow through the outside, such as for heat exchange tubes in petrochemical production or on seawater ships. The diffusion-combined heat treatment process involves a temperature of 800°C, a pressure of 10 MPa, a holding time of 4 hours, and air cooling.

[0058] A corrugated copper tube for heat exchange includes a corrugated tube base 1, with three spiral grooves 2 on the outer wall of the corrugated tube base 1 for refrigerant flow; it also includes a sheath 3 fitted over the corrugated tube base 1, and the sheath 3 is fixedly connected to the crest of the corrugated tube base 1. The corrugated tube base 1 has an internal thread 4 inside, and the thread teeth 5 of the internal thread 4 are irregularly shaped with multiple stepped teeth on both sides. The specific 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 height of the internal thread 4 is 0.15mm, the tooth root wall thickness is 0.25mm, the tooth tip angle is 35°, and the number of internal threads 4 is 100 per turn; the number of corrugated tube stretching turns is 15 turns, and the depth of the clamping claw of the tube groove 2 is 3mm; the sheath 3 is made of smooth titanium tube, with a wall thickness of 0.2mm, an inner diameter of 8.2mm, and an outer diameter of 8mm after sleeve pulling.

[0059] Comparative Example 1

[0060] This embodiment uses copper tubes with small wall thickness and outer diameter. The structure of this embodiment is put into use and is mainly used in common heat exchangers and water heater main pipes. The temperature of the diffusion-bonded heat treatment process is 700℃, the pressure is 10MPa, the heat preservation time is 3h, and the cooling method is air cooling.

[0061] A corrugated copper tube for heat exchange includes a corrugated tube base 1, with three spiral grooves 2 on the outer wall for refrigerant flow; it also includes a sheath 3 fitted over the corrugated tube base 1, and the sheath 3 is fixedly connected to the crests of the corrugated tube base 1. The corrugated tube base 1 has an internal thread 4, and the thread teeth 5 of the internal thread 4 are of a multi-layered stepped profile with irregular teeth on both sides. The specific parameters of each structure in the above corrugated copper tube are as follows:

[0062] The corrugated pipe base 1 has a wall thickness of 0.2mm and an outer diameter of 4mm; the internal thread 4 has a thread tooth height of 0.1mm, a tooth root wall thickness of 0.1mm, a tooth tip angle of 35°, and 30 internal threads per turn; the corrugated pipe has 10 stretching turns, and the pressure claw depth of the pipe groove 2 is 2mm; the sheath 3 is made of smooth copper tubing with a wall thickness of 0.1mm, an inner diameter of 4.2mm, and an outer diameter of 4mm after being pulled.

[0063] Comparative Example 2

[0064] Compared with Example 1, this embodiment has basically the same structure, parameters, working environment, and operating parameters. The main difference is that the diffusion-combination heat treatment is increased to 1000℃. The process dimensions used in this embodiment are relatively moderate. The structure of this embodiment is mainly used in environments and media that require good heat exchange performance and are non-corrosive, specifically in common heat exchangers and water heater main pipes. The diffusion-combination heat treatment process has a temperature of 1000℃, a pressure of 10MPa, a holding time of 3 hours, and uses air cooling.

[0065] A corrugated copper tube for heat exchange includes a corrugated tube base 1, with three spiral grooves 2 on the outer wall of the corrugated tube base 1 for refrigerant flow; it also includes a sheath 3 fitted over the corrugated tube base 1, and the sheath 3 is fixedly connected to the crest of the corrugated tube base 1. The corrugated tube base 1 has an internal thread 4 inside, and the thread teeth 5 of the internal thread 4 are irregularly shaped with multiple stepped teeth on both sides. The specific 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 height of the internal thread 4 is 0.4mm, the tooth root wall thickness is 0.4mm, the tooth tip angle is 50°, and the number of internal threads 4 is 300 per turn; the number of corrugated tube stretching turns is 25 turns, and the depth of the pressure claw of the tube groove 2 is 4mm; the sheath 3 is made of pure copper tube, with a wall thickness of 0.3mm, an inner diameter of 12.3mm, and an outer diameter of 12mm after being pulled.

[0066] Comparative Example 3

[0067] Compared with Example 1, this embodiment has basically the same structure, parameters, working environment, and working parameters. The main difference is that the heat treatment holding time for diffusion bonding is increased to 6 hours. The process dimensions used in this embodiment are relatively moderate. The structure of this embodiment is mainly used in environments and media that require good heat exchange performance and are non-corrosive. Specifically, it is used in common heat exchangers and water heater main pipes. The temperature of the diffusion bonding heat treatment process is 700℃, the pressure is 10MPa, the holding time is 6 hours, and the cooling method is air cooling.

[0068] A corrugated copper tube for heat exchange includes a corrugated tube base 1, with three spiral grooves 2 on the outer wall of the corrugated tube base 1 for refrigerant flow; it also includes a sheath 3 fitted over the corrugated tube base 1, and the sheath 3 is fixedly connected to the crest of the corrugated tube base 1. The corrugated tube base 1 has an internal thread 4 inside, and the thread teeth 5 of the internal thread 4 are irregularly shaped with multiple stepped teeth on both sides. The specific 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 height of the internal thread 4 is 0.4mm, the tooth root wall thickness is 0.4mm, the tooth tip angle is 50°, and the number of internal threads 4 is 300 per turn; the number of corrugated tube stretching turns is 25 turns, and the depth of the pressure claw of the tube groove 2 is 4mm; the sheath 3 is made of pure copper tube, with a wall thickness of 0.3mm, an inner diameter of 12.3mm, and an outer diameter of 12mm after being pulled.

[0069] Comparative Example 4

[0070] Compared with Example 1, this embodiment has basically the same structure, parameters, working environment, and working parameters. The main difference is that the outer diameter of the sheath 3 is reduced to 11.4mm after being drawn. The process dimensions used in this embodiment are relatively moderate. The structure of this embodiment is mainly used in environments and media that require good heat exchange performance and are non-corrosive. Specifically, it is used in common heat exchangers and water heater main pipes. The diffusion-combined heat treatment process has a temperature of 700℃, a pressure of 10MPa, a holding time of 6h, and uses air cooling.

[0071] A corrugated copper tube for heat exchange includes a corrugated tube base 1, with three spiral grooves 2 on the outer wall of the corrugated tube base 1 for refrigerant flow; it also includes a sheath 3 fitted over the corrugated tube base 1, and the sheath 3 is fixedly connected to the crest of the corrugated tube base 1. The corrugated tube base 1 has an internal thread 4 inside, and the thread teeth 5 of the internal thread 4 are irregularly shaped with multiple stepped teeth on both sides. The specific 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 height of the internal thread 4 is 0.4mm, the tooth root wall thickness is 0.4mm, the tooth tip angle is 50°, and the number of internal threads 4 is 300 per turn; the number of corrugated tube stretching turns is 25 turns, and the depth of the clamping claw of the tube groove 2 is 4mm; the sheath 3 is made of pure copper tube, with a wall thickness of 0.3mm, an inner diameter of 11.4mm, and an outer diameter of 12mm after being pulled.

[0072] Comparative Example 5

[0073] Compared with Example 1, this embodiment has basically the same structure, parameters, working environment, and operating parameters. The main difference is that the temperature of the diffusion-bonded heat treatment process is reduced to 450℃. The process dimensions used in this embodiment are relatively moderate. The structure of this embodiment is mainly used in environments and media that require good heat exchange performance and are non-corrosive, specifically in common heat exchangers and water heater main pipes. The temperature of the diffusion-bonded heat treatment process is 450℃, the pressure is 10MPa, the holding time is 3h, and the cooling method is air cooling.

[0074] A corrugated copper tube for heat exchange includes a corrugated tube base 1, with three spiral grooves 2 on the outer wall of the corrugated tube base 1 for refrigerant flow; it also includes a sheath 3 fitted over the corrugated tube base 1, and the sheath 3 is fixedly connected to the crest of the corrugated tube base 1. The corrugated tube base 1 has an internal thread 4 inside, and the thread teeth 5 of the internal thread 4 are irregularly shaped with multiple stepped teeth on both sides. The specific 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 height of the internal thread 4 is 0.4mm, the tooth root wall thickness is 0.4mm, the tooth tip angle is 50°, and the number of internal threads 4 is 300 per turn; the number of corrugated tube stretching turns is 25 turns, and the depth of the pressure claw of the tube groove 2 is 4mm; the sheath 3 is made of pure copper tube, with a wall thickness of 0.3mm, an inner diameter of 12.3mm, and an outer diameter of 12mm after being pulled.

[0075] Comparative Example 6

[0076] Compared with Example 1, this embodiment has basically the same structure, parameters, working environment, and operating parameters. The main difference is that a capillary tube is embedded in the tube groove 2, and the refrigerant flows through the capillary tube. The process dimensions used in this embodiment are relatively moderate. The structure of this embodiment is mainly used for non-corrosive media and environments that require good heat exchange performance. Specifically, it is used in common heat exchangers and water heater main pipes. The diffusion combined heat treatment process has a temperature of 450℃, a pressure of 10MPa, a heat preservation time of 3h, and uses air cooling.

[0077] A corrugated copper tube for heat exchange includes a corrugated tube base 1, with three spiral grooves 2 on the outer wall of the corrugated tube base 1 for refrigerant flow; capillary tubes are wound inside the grooves 2, the outer diameter of the wound capillary tubes being 3.8 mm and the wall thickness being 0.5 mm; it also includes a sheath 3 fitted over the corrugated tube base 1, and the sheath 3 being fixedly connected to the crest of the corrugated tube base 1. The corrugated tube base 1 has an internal thread 4 inside, and the thread teeth 5 of the internal thread 4 are shaped with multiple stepped irregular teeth on both sides. The specific 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 height of the internal thread 4 is 0.4mm, the tooth root wall thickness is 0.4mm, the tooth tip angle is 50°, and the number of internal threads 4 is 300 per turn; the number of corrugated tube stretching turns is 25 turns, and the depth of the pressure claw of the tube groove 2 is 4mm; the sheath 3 is made of pure copper tube, with a wall thickness of 0.3mm, an inner diameter of 12.3mm, and an outer diameter of 12mm after being pulled.

[0078] Flow rate and pressure resistance tests were performed on the pipes in each embodiment. 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] Visual inspection: The appearance was observed by visual inspection without magnification; the peak and the area where the three tubes of the sheath meet were observed by microscopic observation with 50x magnification after cutting the sample.

[0080] Flow measurement: A turbine flow meter is used for measurement, which has high measurement accuracy and fast response speed.

[0081] Pressure resistance test: The pressure resistance performance is the ultimate pressure resistance test. The pressure is slowly and continuously increased, and the pressure is maintained for 1 minute for every 0.5 MPa increase. The sample is observed to be free of cracks and leaks (macroscopic deformation that does not cause leakage is allowed). The pressure is then continuously increased until leakage occurs.

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

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

[0084]

[0085] As can be seen from the results in Table 1, the samples in Examples 1-3 of this utility model have a good appearance, and the corrugated peak and the sheath 3 tube are tightly joined without gaps. Furthermore, as can be seen from Examples 1-2 and Comparative Examples 1-5, the corrugated pipes with larger and moderate specifications have good flow rate and pressure resistance.

[0086] In the comparative examples, the copper tube in Comparative Example 1 was too thin, which meant that its strength did not meet the minimum strength requirements for making a corrugated tube, causing the corrugated tube manufacturing process to fail.

[0087] In Comparative Example 2, the high temperature of 1000℃ is close to the melting point of copper, causing the copper tube to partially melt under this high temperature and pressure. After melting, the wall thickness of the sheath 3 is reduced, thus reducing its pressure resistance.

[0088] Comparative Example 3 and Example 1 differ only in the heat preservation time, and it can be seen that there is no significant difference in the experimental results when the heat preservation time is 6h or 3h.

[0089] In Comparative Example 4, because the outer diameter after drawing is smaller than the size ratio of the corrugated pipe base 1 and the sheath 3, the corrugated pipe base 1 protrudes, resulting in a protrusion in appearance.

[0090] In Comparative Example 5, the heating temperature was not reached properly, which prevented the formation of an effective metallurgical bonding interface between the corrugated pipe base 1 and the sheath 3, resulting in gaps. These gaps caused the gas in the three pipe grooves 2 to intrude into each other, leading to turbulent gas flow, mutual interference, and a reduction in directional flow.

[0091] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model and are not intended to limit it. Although this utility model has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this utility model without departing from the spirit and scope of the technical solutions of this utility model, and all such modifications and substitutions should be covered by the claims of this utility model.

Claims

1. A corrugated copper tube for heat exchange, characterized in that, It includes a corrugated pipe base (1), on the outer wall of which is provided a spiral groove (2) for the flow of refrigerant; it also includes a sheath (3) sleeved on the outside of the corrugated pipe base (1), and the sheath (3) is fixedly connected to the outer periphery of the corrugated pipe base (1).

2. The corrugated copper tube for heat exchange according to claim 1, characterized in that, There are three or more pipe trenches (2), and the inlet and outlet of each pipe trench (2) are independent of each other.

3. The corrugated copper tube for heat exchange according to claim 1 or 2, characterized in that, The corrugated pipe base (1) has internal threads (4).

4. The corrugated copper tube for heat exchange according to claim 3, characterized in that, The internal thread (4) has a thread tooth (5) shape with multiple stepped irregular teeth on both sides.

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

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

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 pipe substrate (1) is 0.3mm-15mm and the diameter is 5mm-80mm.

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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