A composite heat exchange tube capable of synchronous thermal expansion

Abstract

This invention discloses a composite heat exchange tube capable of synchronous thermal expansion. The composite heat exchange tube is composed of an inner tube and an outer tube. The inner tube is a polymer expansion tube, and the outer tube is a metal tube. The polymer expansion tube is made of shape memory polymer material. The composite heat exchange tube provided by this invention possesses the rigidity and strength of metal, while also possessing the good elasticity and corrosion resistance of polymer materials. Furthermore, the expansion coefficient of the heat exchange tube made of composite material is the same as that of the metal tube, avoiding material separation caused by inconsistent expansion of the two materials during the manufacture of heat exchanger equipment, which would lead to increased thermal resistance and reduced heat transfer coefficient of the heat exchanger.

Description

Technical Field

[0001] This invention relates to the field of heat exchanger technology, and more specifically to a composite heat exchange tube capable of synchronous thermal expansion. Background Technology

[0002] The main pipe expansion processes include: internal pressure method, vacuum method, and a combination of internal pressure and vacuum method. Chinese patent document CN116039065A uses the internal pressure and vacuum combination method to expand the pipe. Inside the heating cylinder, the internal and external pressures of the heat shrink tubing are in a balanced state. After the heat shrink tubing enters the expansion mold from the heating cylinder, the external pressure is released to expand the tubing. A mold is required during the expansion process; the mold causes some damage to the pipe, and a certain machining allowance needs to be left for the pipe wall thickness. Chinese patent document CN201210292151.X discloses an automatic control system for internal pressure in heat shrink tubing expansion and a heat shrink tubing expansion system that uses the internal pressure method. Its control strategy is to use internal pressure control to achieve accurate pipe diameter expansion. The expanded pipe diameter is a function of the current temperature and pressure. Therefore, there are two methods to control the expanded pipe diameter: Method 1 controls the pressure difference between the inside and outside of the pipe; Method 2 controls the pipe temperature. Studies have shown that: (1) After expansion, the pipe diameter is directly proportional to the first power of the pressure and the propagation speed of the pressure is the speed of sound of the medium inside the pipe. The response is too sensitive and difficult to converge. When there are fluctuations, it is difficult to achieve stability in a short time; (2) After expansion, the pipe diameter is directly proportional to the square power of the temperature and the temperature inertia is relatively large, making it easy to converge.

[0003] How to control the diameter of expanded pipes without using molds is a challenge in this field.

[0004] Furthermore, heat exchange tubes are a key component of heat exchangers. Heat exchange tubes made of composite materials possess the rigidity and strength of metals, while also exhibiting the excellent elasticity and corrosion resistance of polymer materials. The core of composite heat exchange tubes lies in solving the problem of the significant difference in thermal expansion coefficients between plastic pipes and metals. The thermal expansion coefficient of plastic is approximately 10 times that of metal. Due to the functional technology of heat exchangers—heating and cooling—the thermal expansion of the two composite materials cannot be controlled at high temperatures.

[0005] Chinese patent document CN111895850A discloses a corrosion-resistant composite heat exchange tube. The core of this patent utilizes a thermal interface material of unknown composition. This material possesses good deformation properties, thermal conductivity, and filling properties, and its morphology changes uniformly with the thermal deformation of the interface between the metal and non-metal tubes as temperature changes. Specifically, the portion in contact with the metal tube changes with the shape of the metal tube, and the portion in contact with the non-metal tube changes with the shape of the non-metal tube. This eliminates thermal stress caused by temperature changes when the metal and non-metal tubes are used in combination, improving both the operational safety of the heat exchange tube and the heat exchanger, and increasing heat transfer efficiency. However, this patent requires the use of additional thermal interface material, and the use of this material also increases the number of steps involved in the composite process of the metal and non-metal tubes. Summary of the Invention

[0006] The purpose of this invention is to provide a composite heat exchange tube that can expand synchronously, so as to solve or improve the problem that the coefficients of thermal expansion of polymer tubes and metal tubes in composite heat exchange tubes are inconsistent and the thermal expansion of composite materials cannot be controlled at high temperatures when manufacturing heat exchanger equipment.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: a composite heat exchange tube capable of synchronous thermal expansion, wherein the composite heat exchange tube is composed of an inner tube and an outer tube; the outer tube is a polymer expansion tube, and the inner tube is a metal tube; the polymer expansion tube is made of shape memory polymer material.

[0008] As a preferred embodiment of the composite heat exchanger tube capable of synchronous thermal expansion as described above, the combination of the inner and outer tubes includes the following steps: S21. The metal tube is placed in the inner cavity of the polymer expansion tube to obtain a combined pipe; S22. The combined pipe is placed on a pre-furnace pipe conveyor, which sends the combined pipe into a vacuum heating furnace. The vacuum heating furnace heats the combined pipe and holds it at a set temperature. Then, the vacuum heating furnace is brought under negative pressure and begins to cool down; S23. The temperature in the vacuum heating furnace is held down after dropping to a set value, and then the vacuum is released; S24. The pipe is sent to a post-furnace pipe guide, and a cooler is used to cool it down and / or the surface temperature of the pipe is detected during the transport process.

[0009] As a preferred embodiment of the composite heat exchanger tube capable of synchronous thermal expansion as described above: the polymer diffusion tube is obtained by expanding the polymer material tube using a polymer tube internal pressure expansion system; the polymer tube internal pressure expansion system includes: a tube feeder for conveying the polymer material tube; a tube diameter measuring instrument for detecting at least the diameter of the expanded polymer material tube; and a temperature-controlled vertical kiln, the temperature-controlled vertical kiln having a polymer material tube inlet at the top and a polymer material tube outlet at the bottom, the temperature-controlled vertical kiln being used for countercurrent heating of the polymer material tube; An expanded pipe rewinder is provided for rewinding the expanded polymer pipe; a gas source is provided for supplying gas to the polymer material pipe, and a downstream pressure regulating valve is provided on the connecting pipe between the gas source and the polymer material pipe; a control system is connected to the pipe feeder, the pipe diameter measuring instrument, the temperature-controlled vertical kiln, the expanded pipe rewinder, and the downstream pressure regulating valve; the control system is at least used to adjust the pipe feeding speed of the pipe feeder and / or the opening degree of the downstream pressure regulating valve according to the expanded pipe diameter of the polymer material pipe detected by the pipe diameter measuring instrument.

[0010] As a preferred embodiment of the composite heat exchanger tube capable of synchronous thermal expansion as described above: the temperature-controlled vertical kiln is a multi-section temperature-controlled vertical kiln; from top to bottom, the set temperature of the temperature-controlled vertical kiln increases.

[0011] As a preferred embodiment of the composite heat exchanger tube capable of synchronous thermal expansion as described above: the polymer tube internal pressure expansion system further includes: a front guide tube and a rear guide tube, which are respectively connected to both ends of the polymer material tube; an unexpanded pipe turntable, which is used to transport the polymer material tube to the pipe feeder; a pipe surface temperature measuring device, which is used to detect the surface temperature of the pipe emerging from the bottom of the temperature-controlled vertical kiln; and a pipe cooler, which is used to cool the pipe emerging from the bottom of the temperature-controlled vertical kiln; the unexpanded pipe turntable, the pipe surface temperature measuring device, and the pipe cooler are signal-connected to the control system.

[0012] As a preferred embodiment of the composite heat exchanger tube capable of synchronous thermal expansion as described above: the tube diameter measuring instrument includes a pre-furnace tube diameter measuring instrument and a post-furnace tube diameter measuring instrument, the pre-furnace tube diameter measuring instrument is disposed between the tube feeder and the temperature-controlled vertical kiln, and the post-furnace tube diameter measuring instrument is disposed between the pipe cooler and the expanded pipe rewinder; guide rollers are provided between the unexpanded pipe turntable and the tube feeder and / or between the pre-furnace tube diameter measuring instrument and the temperature-controlled vertical kiln.

[0013] As a preferred embodiment of the composite heat exchanger tube capable of synchronous thermal expansion as described above, the fabrication of the polymer expansion tube includes the following steps: S10. One end of the polymer material tube is sealed, and the other end is connected to a gas source. After maintaining this connection for a set time, the pressure is released; S11. The polymer material tube is connected to the gas source, and the tube feeder sends the polymer material tube into the temperature-controlled vertical kiln; S12. The temperature-controlled vertical kiln performs countercurrent heating on the polymer material tube; S13. The tube diameter measuring instrument at least measures the diameter of the expanded polymer material tube; S14. The expanded tube rewinder... The polymer expansion tube is wound up; the control system accelerates the operation speed of the tube feeder when the tube diameter measuring instrument detects that the expanded diameter of the polymer material tube is greater than a set value, and slows down the operation speed of the tube feeder when the tube diameter measuring instrument detects that the expanded diameter of the polymer material tube is less than a set value; and / or, decreases the opening of the downstream pressure regulating valve when the tube diameter measuring instrument detects that the expanded diameter of the polymer material tube is greater than a set value, and increases the opening of the downstream pressure regulating valve when the tube diameter measuring instrument detects that the expanded diameter of the polymer material tube is less than a set value.

[0014] As a preferred embodiment of the composite heat exchanger tube capable of synchronous thermal expansion as described above: the temperature-controlled vertical kiln is a three-section temperature-controlled vertical kiln, wherein the temperature of the top preheating section of the temperature-controlled vertical kiln is 270℃±1℃, the temperature of the middle section is 370℃±1℃, and the temperature of the bottom section is 410℃±1℃.

[0015] As a preferred embodiment of the composite heat exchanger tube capable of synchronous thermal expansion as described above: before step S10, the method further includes connecting the front guide tube and the rear guide tube to the two ends of the polymer material tube respectively; in step S10, the gas pressure is adjusted to one-fifth of the pipe burst pressure, the pressure is maintained for 10 minutes, and the pressure is released after no change; before the polymer material tube enters the tube feeder, it is set on the unexpanded pipe turntable; after being processed by the temperature-controlled vertical kiln, before entering the expanded pipe rewinder, the method further includes detecting the pipe surface temperature with a pipe surface temperature measuring device and cooling the pipe with a pipe cooler.

[0016] As a preferred embodiment of the composite heat exchanger tube capable of synchronous thermal expansion as described above: the front guide tube enters the temperature-controlled vertical kiln before the polymer material tube, and is connected to the gas source after being wound up by the expanded pipe rewinder.

[0017] The present invention has the following advantages:

[0018] (1) The composite heat exchange tube that can expand synchronously provided by the present invention has the rigidity and strength of metal, and at the same time has the good elasticity and corrosion resistance of polymer material. In addition, the expansion coefficient of the heat exchange tube made of composite material is the same as that of metal, which avoids the separation of the two materials of composite heat exchange tube due to inconsistent expansion when manufacturing heat exchanger equipment, resulting in increased thermal resistance and reduced heat transfer coefficient of heat exchanger.

[0019] (2) The manufacturing process of the synchronously thermally expandable composite heat exchanger tube of the present invention is carried out in a vacuum, and there is no gap between the two tubes during the composite process. First, the polymer material itself has thermal shrinkage properties, which are fixed by heating and tightly wrapped around the surface of the metal tube. The force exerted by the polymer material on the metal tube includes both the elastic force of the material itself and the pressure generated by the negative pressure. The two forces firmly fix the polymer material to the surface of the metal material, realizing the composite of the two materials and producing the synchronously thermally expandable composite heat exchanger tube of the present invention.

[0020] (3) In the manufacturing process of the polymer expansion tube in the synchronously thermally expanding composite heat exchange tube of the present invention, no mold is required. The advantage of not requiring a mold is that it will not cause secondary damage to the pipe, since the mold will exert a strong reaction force on the pipe. The reason why the polymer tube internal pressure expansion system used in the manufacturing process of the polymer expansion tube of the present invention does not require a mold is that: the positive pressure inside the pipe is greater than the deformation pressure at high temperature. The temperature-controlled vertical kiln is used to perform countercurrent heating on the polymer material tube, which expands from its original size to the required outer diameter size under the action of internal pressure and high temperature. After exiting the kiln, the pipe cools down rapidly. Because of the decrease in pipe temperature, the pipe diameter no longer increases but remains at the required size. The polymer tube internal pressure expansion system used in the present invention can control the expanded pipe diameter by controlling the internal pressure and the feeding speed of the feeder. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of a polymer tube internal pressure expansion system provided in one embodiment of the present invention.

[0022] Figure 2 This is a schematic diagram of a composite heat exchanger tube fabrication system capable of synchronous thermal expansion, provided in one embodiment of the present invention.

[0023] Figure 3 This is a schematic diagram of the structure of a composite heat exchange tube capable of synchronous thermal expansion provided in one embodiment of the present invention (without gap between the outer tube and the inner ring, under vacuum).

[0024] Figure 4 This is a schematic diagram of the secondary sealing process during the molding of a heat exchanger device according to an embodiment of the present invention.

[0025] In the picture:

[0026] 101. Unexpanded pipe turntable; 102. Temperature-controlled vertical kiln; 103. Expanded pipe winder; 104. Front pipe diameter measuring instrument; 105. Rear pipe diameter measuring instrument; 106. Pipe feeder; 107. Front guide pipe; 108. Rear guide pipe; 109. Pipe cooler; 110. Post-valve pressure regulating valve; 111. Gas source; 112. Pipe surface temperature measuring instrument; 113. Control system; 114. Guide wheel;

[0027] 201. Front-end pipeline conveyor; 202. Vacuum heating furnace; 203. Rear-end pipeline surface temperature measuring device; 204. Rear-end pipeline cooler; 205. Rear-end pipeline guide; 206. Cooled pipeline surface temperature measuring device; 207. Process controller;

[0028] 301 - Polymer expansion tube; 302 - Metal tube; 303 - Sealing ring. Detailed Implementation

[0029] The preferred embodiments of the present invention will now be described in detail with reference to examples. It should be understood that the following examples are given for illustrative purposes only and are not intended to limit the scope of protection of the present invention. Those skilled in the art can make various modifications and substitutions to the present invention without departing from its spirit and intent, and all such modifications and substitutions fall within the scope of protection claimed in the present invention.

[0030] To address the problem of inconsistent thermal expansion coefficients between polymer tubes and metal tubes in composite heat exchanger tubes during the manufacturing of heat exchanger equipment, and the uncontrollable thermal expansion of composite materials at high temperatures, this invention proposes a composite heat exchanger tube capable of synchronous thermal expansion.

[0031] The composite heat exchange tube of the present invention is capable of synchronous thermal expansion. The composite heat exchange tube is composed of an inner tube and an outer tube. The outer tube is a polymer expansion tube and the inner tube is a metal tube (the material of the outer tube includes, but is not limited to, copper, aluminum, steel, and titanium). The polymer expansion tube is made of shape memory polymer material (that is, within a certain range, the material that expands and cools to shape can shrink back to its original shape after being heated).

[0032] Shape memory polymer materials include, but are not limited to, fluoroplastics and ethylene materials. These are then combined with metal tubes to create heat exchanger pipes. The inside of the pipes carries a non-corrosive or weakly corrosive medium (the metal tube serves as the inner tube), while the outside carries a strongly corrosive medium (the polymer material tube serves as the outer tube).

[0033] The composite heat exchange tube of this invention, capable of synchronous thermal expansion, possesses the rigidity and strength of metal while also exhibiting the excellent elasticity and corrosion resistance of polymer materials. During heat exchanger fabrication, a corrosive medium flows through the outer side (shell side) of the tube, as the outer material is a polymer, which possesses the corrosion resistance inherent to the tube's own material. For example, the heat transfer medium outside the tube is highly corrosive flue gas. The inner side (tube side) can flow with non-corrosive media such as air and water. Utilizing the strength of metal, the inner side can withstand media with higher pressure. While polymer materials have good corrosion resistance, their pressure-bearing capacity is weak. This process utilizes the corrosion resistance of polymer materials while simultaneously improving the pressure-bearing capacity of the heat exchange tube. Furthermore, the expansion coefficient of the heat exchange tube made from the composite material is the same as that of the metal tube, preventing material separation due to inconsistent expansion between the two materials during heat exchanger fabrication. This avoids increased thermal resistance and a reduced heat transfer coefficient.

[0034] Preferably, the composite heat exchange tube capable of synchronous thermal expansion in this embodiment of the invention is obtained by combining a polymer expansion tube with a metal tube in a vacuum.

[0035] The manufacturing process of the synchronously thermally expanding composite heat exchanger tube of the present invention employs a vacuum composite method. During the composite process, there are no gaps between the two types of pipes, and the composite is performed in a vacuum. Firstly, the polymer material itself possesses thermal shrinkage properties; after heating and stabilization, it is firmly wrapped around the metal surface. The force exerted includes both the elasticity of the polymer material itself and the pressure generated by the negative pressure (e.g., 0.1 MPa). These two forces firmly bind the polymer material to the metal material, achieving the composite of the polymer expansion tube and the metal tube.

[0036] The composite heat exchanger tube with synchronous thermal expansion of the present invention is composited in a composite shaping system. The composite shaping system includes a furnace front pipe conveyor 201, a vacuum heating furnace 202, a furnace rear surface temperature measuring device 203, a furnace rear pipe cooler 204, a furnace rear pipe guide 205, a cooled pipe surface temperature measuring device 206, and a process controller 207. The process controller 207 is connected to the furnace front pipe conveyor 201, the vacuum heating furnace 202, the furnace rear surface temperature measuring device 203, the furnace rear pipe cooler 204, the furnace rear pipe guide 205, and the cooled pipe surface temperature measuring device 206.

[0037] Preferably, the manufacturing process of the composite heat exchange tube capable of synchronous thermal expansion of the present invention includes the following steps:

[0038] S21. Cut the polymer expansion tube to the required heat exchange tube length + twice the tube diameter; cut the metal tube to the required heat exchange tube length; the wall thickness of the metal tube is calculated based on the pressure required by the internal medium. Insert the metal tube into the cut polymer expansion tube, leaving one tube diameter length at each end to obtain the combined pipe.

[0039] S22. Activate the composite shaping system (e.g.) Figure 2 As shown, the combined pipeline is placed in the pipeline conveyor 201 in front of the furnace and then sent into the vacuum heating furnace 202. The temperature is raised to 400°C. After the temperature reaches 400°C and is maintained for 20 minutes, the vacuum pumping device of the vacuum heating furnace 202 is turned on to maintain the vacuum negative pressure in the vacuum heating furnace 202 at -0.01MPa, and then the cooling begins.

[0040] S23. The temperature is lowered to 50°C and maintained for 20 minutes, then the vacuum is released and the pressure is restored to atmospheric pressure, thus realizing the composite of the polymer expansion tube and the metal tube, and obtaining the composite heat exchange tube of the present invention that can expand synchronously (e.g., Figure 3 (As shown).

[0041] S24. Turn on the mesh belt of the vacuum heating furnace 202 and send the composite heat exchange tube that can be synchronously thermally expanded to the furnace back pipe guide 205. During the transportation process, the furnace back pipe cooler 204 cools down the pipe. The furnace back surface temperature measuring device 203 and the cooled pipe surface temperature measuring device 206 detect the temperature and trigger an over-temperature alarm.

[0042] The above steps are controlled by the process controller 207.

[0043] Furthermore, when assembling the synchronously thermally expanding composite heat exchanger tube of the present invention into a heat exchanger, a double-end expansion process can be adopted to form a secondary seal (sealing ring 303). This ensures that a vacuum state is maintained between the two materials in the hot state, and that the two materials (polymer expansion tube 301 and metal tube 302) are tightly bonded together under the action of vacuum negative pressure. This prevents a significant decrease in the heat transfer coefficient due to thermal expansion separation (e.g., ...). Figure 4 (As shown).

[0044] Preferably, the polymer expansion tube in the composite heat exchanger tube capable of synchronous thermal expansion of the present invention employs a polymer tube internal pressure expansion system (see reference). Figure 1 ; Figure 1The elevation of the upper platform is higher than that of the lower platform and should be greater than 1.4 times the pipe bend radius; this is because if the elevation difference is too small, the pipe will bend when turning. This is used to expand the polymer material pipe. The polymer pipe internal pressure expansion system includes: a pipe feeder 106, used to transport the polymer material pipe; a pipe diameter measuring instrument, used at least to detect the diameter of the expanded polymer material pipe; a temperature-controlled vertical kiln 102, with a polymer material pipe inlet at the top and a polymer material pipe outlet at the bottom, used for countercurrent heating of the polymer material pipe; and an expanded pipe rewinder 103, used to rewind the expanded pipe. The reel 103 is used to reel in the polymer expanded tube; the gas source 111 is used to supply gas to the polymer material tube, and a downstream pressure regulating valve 110 is provided on the connecting pipeline between the gas source 111 and the polymer material tube; the control system 113 is connected to the pipe feeder 106, the pipe diameter measuring instrument, the temperature-controlled vertical kiln 102, the expanded pipe reel 103, and the downstream pressure regulating valve 110 via signal connection (signal connection means connection via signal line or wireless connection); the control system 113 is used to adjust the pipe feeding speed of the pipe feeder 106 and / or the opening of the downstream pressure regulating valve 110 according to the expanded pipe diameter of the polymer material tube detected by the pipe diameter measuring instrument.

[0045] The polymer tube internal pressure expansion system of this invention does not require a mold. The advantage of not requiring a mold is that it avoids secondary damage to the pipe, since a mold would exert a forceful reaction on the pipe. The reason why the polymer tube internal pressure expansion system of this invention does not require a mold is that the positive pressure inside the pipe is greater than the deformation pressure at high temperature. The temperature-controlled vertical kiln 102 is used to perform countercurrent heating on the polymer material pipe (preferably, the high-temperature zone of the temperature-controlled vertical kiln 102 is 20-30cm long and is located at the bottom of the temperature-controlled vertical kiln 102, and the polymer material pipe deforms at ±10-15cm from the outlet). That is, the original size increases to the required outer diameter size under the action of internal pressure and high temperature. After exiting the kiln, the pipe cools down rapidly. Because of the decrease in pipe temperature, the pipe diameter no longer increases but remains at the required size. The polymer tube internal pressure expansion system of the present invention can control the expanded tube diameter according to the internal pressure (for example, the opening degree of the air source 111 can be adjusted by the pressure regulating valve 110 after the valve, thereby realizing the regulation of the internal pressure; preferably, the present invention controls the internal pressure with an accuracy of ±1Pa; the expanded tube diameter is the same as the first power of the pressure, and only the internal pressure needs to be precisely controlled to obtain the required expanded tube diameter) and the feeding speed of the pipeline (the feeding speed of the polymer material tube can be adjusted by the tube feeder 106, and the tube feeder 106 can be a speed adjustable tube feeder 106). This polymer tube internal pressure expansion system helps to solve or improve the problems of current pipeline expansion processes, such as the need for molds, which can cause certain damage to the pipeline; the large inertia, long feedback time, and easy non-convergence of control strategies when using temperature to achieve pipeline expansion; or the overly sensitive and difficult-to-converge response under pressure fluctuations when using pressure control to achieve pipeline expansion, making it difficult to achieve stability in a short period of time. The polymer pipe internal pressure expansion system can precisely control the pipe heating time by controlling the pipe feeding speed of the pipe feeder 106, thereby accurately controlling the pipe diameter.

[0046] Preferably, in the polymer tube internal pressure expansion system used in this invention, the temperature-controlled vertical kiln 102 is a multi-segment temperature-controlled vertical kiln 102 (the furnace temperature control of the temperature-controlled vertical kiln 102 can adopt PID control to ensure that the furnace temperature control accuracy is less than ±1℃); from top to bottom, the set temperature of the temperature-controlled vertical kiln 102 increases. That is, the temperature-controlled vertical kiln 102 in the polymer tube internal pressure expansion system of this invention can realize vertical countercurrent heating of the polymer tube. The polymer material tube is fed in from the top of the temperature-controlled vertical kiln 102 and discharged from the bottom. The furnace temperature control increases from top to bottom, and multiple segments are set (2 or more segments; for example, 3 segments). Countercurrent heating can ensure that the lowest point of the furnace temperature coincides with the lowest point of the pipe (polymer material tube) temperature; and ensure that the highest point of temperature (the point with the largest diameter of the polymer material tube) appears at the furnace opening outer diameter measurement point. Furthermore, the vertical arrangement creates a chimney effect, causing the hot air to flow naturally upwards, further enabling precise control of the furnace temperature (the pipes to be heated move from top to bottom, with the temperature gradually increasing, while the hot air moves from bottom to top due to the chimney effect, thus creating a counter-current flow. This keeps the temperature difference between the pipes and the hot air constant, or relatively constant, and the heating power depends on the temperature difference between the hot air and the pipes it contacts. In a counter-current arrangement, the temperature difference remains relatively stable during the dynamic process, resulting in a relatively constant output power and more precise furnace temperature control).

[0047] Preferably, the polymer tube internal pressure expansion system used in this invention further includes: a front guide tube 107 and a rear guide tube 108, which are respectively connected to both ends of the polymer material tube (the front guide tube 107 and the rear guide tube 108 allow for convenient introduction of high-pressure compressed air into the tube cavity of the polymer material tube); an unexpanded pipe turntable 101, which is used to transport the polymer material tube to the pipe feeder 106; a pipe surface temperature measuring device 112, which is used to detect the surface temperature of the pipe passing through the bottom of the temperature-controlled vertical kiln 102; and a pipe cooler 109, which is used to cool the pipe passing through the bottom of the temperature-controlled vertical kiln 102; the unexpanded pipe turntable 101, the pipe surface temperature measuring device 112, and the pipe cooler 109 are connected to the control system 113 via signals.

[0048] Preferably, in the polymer tube internal pressure expansion system used in this invention, the tube diameter measuring instrument includes a pre-furnace tube diameter measuring instrument 104 and a post-furnace tube diameter measuring instrument 105. The pre-furnace tube diameter measuring instrument 104 is disposed between the tube feeder 106 and the temperature-controlled vertical kiln 102, and the post-furnace tube diameter measuring instrument 105 is disposed between the pipe cooler 109 and the expanded pipe rewinder 103. Guide rollers 114 are provided between the unexpanded pipe turntable 101 and the tube feeder 106 and / or between the pre-furnace tube diameter measuring instrument 104 and the temperature-controlled vertical kiln 102. The installation of the pre-furnace pipe diameter measuring instrument 104 and the post-furnace pipe diameter measuring instrument 105 allows for the detection of the pipe diameter before and after expansion of the polymer material pipe, respectively. This enables the control system 113 to adjust the pipe feeding speed of the pipe feeder 106, the speed of the expanded pipe rewinder 103 (preferably, the operating speed of the expanded pipe rewinder 103 is consistent with the pipe feeding speed of the pipe feeder 106), and the internal pressure in the polymer pipe internal pressure expansion system of the present invention after receiving the signal, thereby ensuring the effectiveness of the polymer material pipe expansion.

[0049] Preferably, the processing technology of the polymer expansion tube in the composite heat exchanger tube capable of synchronous thermal expansion of the present invention includes the following steps:

[0050] S10. Start the temperature-controlled vertical kiln 102. The top preheating section temperature is 270℃, the middle section temperature is 370℃, and the bottom section temperature is 410℃. The temperature control uses PID control to ensure a temperature control accuracy of less than ±1℃. Then, wind the polymer material tube to be expanded onto the unexpanded pipe turntable 101. The polymer material tube is defect-free. Connect the front guide pipe 107 and the rear guide pipe 108 to both ends of the polymer material tube (the front guide pipe 107 and the rear guide pipe 108 are connected to the polymer material tube through connectors), and seal them well. The front and rear guide pipes are high-temperature resistant corrugated stainless steel hoses. The rear guide pipe 108 is connected to the pressure regulating valve 110 and the air source 111 through the air pipe connection valve. The front end of the front guide pipe 107 is plugged to prevent leakage. Turn on the gas source 111 switch to introduce gas source 111. Gas source 111 can be nitrogen or other inert gas (compressed air can be used for materials with an oxygen index greater than 50). The gas source pressure should be higher than 0.2 MPa. Open the pressure regulating valve 110 after the valve to adjust the pressure to one-fifth of the pipeline burst pressure and maintain the pressure for 10 minutes. If the pressure does not change, open the plug of the front guide pipe 107 to release the pressure. The pressure regulating valve 10 after the valve will then switch to automatic operation. In this step, before the polymer material pipe enters the temperature-controlled vertical kiln 102, the front guide pipe 107 and the rear guide pipe 108 are connected to the two ends of the polymer material pipe respectively, and the gas source is connected to make the gas source pressure higher than 0.2 MPa. Then, the pressure regulating valve 110 after the valve is opened to adjust the pressure to one-fifth of the pipeline burst pressure and maintain it for 10 minutes, so that pressure can be introduced into the polymer material pipe to increase the pipeline strength.

[0051] S11. Then, first connect the rear guide pipe 108 to the air source, and send the front guide pipe 107 into the pipe feeder 106 (the speed of the pipe feeder 106 is adjustable). The speed is controlled at 1 m per minute. The front guide pipe 107 drives the polymer material pipe and sends it into the temperature-controlled vertical kiln 102 through the guide wheel 114. After the front guide pipe 107 passes through the temperature-controlled vertical kiln 102, it enters the expanded pipe winding device 103. Then, connect the air source 111 of the lower platform of the pipe diameter (at this time, the end of the polymer material pipe connected to the front guide pipe 107 and the end connected to the rear guide pipe 108 are both connected to the air source, which is a dual air source supply to ensure constant pressure in the pipe. This setting ensures that even if there is air entrapment in the pipe during the pipeline transportation process, the air pressure in the pipe can still be maintained, while ensuring the expanded pipe diameter). The expanded pipe winding device 103 is an automatic winding device, and its speed is synchronized with the pipe feeder 106.

[0052] S12. After the polymer material tube exits the temperature-controlled vertical kiln 102, the control system 113 switches to automatic operation (the temperature control system adopts a PID regulation system).

[0053] S13. The tube feeder 106 is controlled according to the expanded tube diameter. If the expanded polymer tube diameter is larger than the required diameter, the feeding speed of the tube feeder 106 is increased; if the expanded polymer tube diameter is smaller than the required diameter, the feeding speed of the tube feeder 106 is decreased. The speed of the expanded tube retractor 103 is adjusted according to the speed of the tube feeder 106 (keeping it consistent with the speed of the tube feeder 106). The downstream pressure regulating valve 110 (including the downstream pressure regulating valve connected to the front guide pipe 107 and the downstream pressure regulating valve connected to the rear guide pipe 108) adjusts the gas pressure according to the tube diameter measured by the downstream tube diameter measuring instrument 105. Specifically, the obtained tube diameter is 1.5 times the required outer diameter of the heat exchange tube, with an accuracy controlled within ±5mm.

[0054] S14. When the length of the guide tube 108 entering the pipe cooler 109 reaches 1 meter, the polymer pipe internal pressure expansion system of the present invention stops operating (the polymer expansion tube obtained after cooling by the pipe cooler 109 can maintain the expanded pipe diameter). The downstream pressure regulating valve 110 automatically adjusts the pressure to ambient atmospheric pressure. Remove the expanded polymer finished pipe (polymer expansion tube).

Claims

1. A composite heat exchange tube capable of synchronous thermal expansion, characterized in that, The composite heat exchange tube is composed of an inner tube and an outer tube; the outer tube is a polymer expansion tube, and the inner tube is a metal tube. The polymer expansion tube is made of shape memory polymer material; The assembly of the inner and outer tubes includes the following steps: S21. The metal tube is placed inside the cavity of the polymer expansion tube to obtain a combined pipe; S22. The combined pipeline is placed on the furnace front pipeline conveyor, which sends the combined pipeline into the vacuum heating furnace. The vacuum heating furnace heats the combined pipeline and holds it at a set temperature. Then, the vacuum heating furnace is made to be under negative pressure and begins to cool down. S23. After the temperature inside the vacuum heating furnace drops to the set value, maintain the temperature and then release the vacuum; S24. Send the pipeline to the furnace post-pipeline guide and use a cooler to cool it down and / or detect the surface temperature of the pipeline during the transport process.

2. The composite heat exchanger tube capable of synchronous thermal expansion as described in claim 1, characterized in that, The polymer expansion tube is obtained by expanding a polymer material tube using a polymer tube internal pressure expansion system; the polymer tube internal pressure expansion system includes: A tube feeder, used to deliver the polymer material tube; A pipe diameter measuring instrument, wherein the pipe diameter measuring instrument is used at least to detect the diameter of the expanded polymer material pipe; A temperature-controlled vertical kiln, wherein the top of the temperature-controlled vertical kiln has an inlet of a polymer material tube and the bottom has an outlet of a polymer material tube, and the temperature-controlled vertical kiln is used to perform countercurrent heating on the polymer material tube; An expanded pipe winder is used to wind up the polymer expanded pipe. A gas source, which is at least used to supply gas to the polymer material tube, and a pressure regulating valve is provided on the connecting pipeline between the gas source and the polymer material tube; The control system is connected to the pipe feeder, the pipe diameter measuring instrument, the temperature-controlled vertical kiln, the expanded pipe winder, and the downstream pressure regulating valve. The control system is at least used to adjust the pipe feeding speed of the pipe feeder and / or the opening degree of the downstream pressure regulating valve according to the expanded pipe diameter of the polymer material pipe detected by the pipe diameter measuring instrument.

3. The composite heat exchanger tube capable of synchronous thermal expansion as described in claim 2, characterized in that, The temperature-controlled vertical kiln is a multi-section temperature-controlled vertical kiln; from top to bottom, the set temperature of the temperature-controlled vertical kiln increases.

4. The composite heat exchanger tube capable of synchronous thermal expansion as described in claim 2, characterized in that, The polymer tube internal pressure expansion system also includes: A front guide tube and a rear guide tube, wherein the front guide tube and the rear guide tube are respectively connected to the two ends of the polymer material tube; An unexpanded pipe turntable is used to transport the polymer material pipe to the pipe feeder; A pipe surface temperature measuring device is used to detect the surface temperature of a pipe that exits from the bottom of the temperature-controlled vertical kiln. A pipe cooler for cooling pipes that extend from the bottom of the temperature-controlled vertical kiln; The unexpanded pipe turntable, pipe surface temperature measuring device, and pipe cooler are signal-connected to the control system.

5. The composite heat exchanger tube capable of synchronous thermal expansion as described in claim 4, characterized in that, The pipe diameter measuring instrument includes a pre-furnace pipe diameter measuring instrument and a post-furnace pipe diameter measuring instrument. The pre-furnace pipe diameter measuring instrument is located between the pipe feeder and the temperature-controlled vertical kiln, and the post-furnace pipe diameter measuring instrument is located between the pipe cooler and the expanded pipe winder. Guide rollers are provided between the unexpanded pipe turntable and the pipe feeder and / or between the furnace front pipe diameter measuring instrument and the temperature-controlled vertical kiln.

6. The composite heat exchanger tube capable of synchronous thermal expansion as described in claim 2, characterized in that, The fabrication of the polymer expansion tube includes the following steps: S10. Seal one end of the polymer material tube and connect the other end to the gas source. After maintaining this for a set time, release the pressure. S11. The polymer material tube is connected to the gas source, and the tube feeder sends the polymer material tube into the temperature-controlled vertical kiln; S12. The temperature-controlled vertical kiln heats the polymer material tube in a countercurrent manner; S13. The pipe diameter measuring instrument shall at least detect the diameter of the expanded polymer material pipe; S14. The expanded pipe winder winds up the polymer expanded pipe; The control system accelerates the pipe feeder's operating speed when the pipe diameter measuring instrument detects that the expanded diameter of the polymer material pipe is greater than a set value, and slows down the pipe feeder's operating speed when the pipe diameter measuring instrument detects that the expanded diameter of the polymer material pipe is less than a set value; and / or, When the pipe diameter measuring instrument detects that the expanded diameter of the polymer material pipe is greater than the set value, the opening of the downstream pressure regulating valve is reduced; when the pipe diameter measuring instrument detects that the expanded diameter of the polymer material pipe is less than the set value, the opening of the downstream pressure regulating valve is increased.

7. The composite heat exchanger tube capable of synchronous thermal expansion as described in claim 6, characterized in that, The temperature-controlled vertical kiln is a three-section temperature-controlled vertical kiln. The temperature of the top preheating section of the temperature-controlled vertical kiln is 270℃±1℃, the middle section temperature is 370℃±1℃, and the bottom section temperature is 410℃±1℃.

8. The composite heat exchanger tube capable of synchronous thermal expansion as described in claim 6, characterized in that, Before step S10, the process also includes connecting the front guide tube and the rear guide tube to the two ends of the polymer material tube respectively; in step S10, the air pressure is adjusted to one-fifth of the pipe burst pressure, the pressure is maintained for 10 minutes, and the pressure is released after there is no change in pressure. Before the polymer material tube enters the tube feeder, it is set on the unexpanded pipe turntable; After being processed in the temperature-controlled vertical kiln, the pipe surface temperature is detected by a pipe surface temperature measuring device and cooled by a pipe cooler before entering the expanded pipe winding device.

9. The composite heat exchanger tube capable of synchronous thermal expansion as described in claim 4, characterized in that, The front guide tube enters the temperature-controlled vertical kiln before the polymer material tube, and is connected to the gas source after being wound up by the expanded pipe winder.

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