Economizer fin with enhanced heat transfer structure and manufacturing method thereof

Abstract

The invention discloses an economizer fin with a reinforced heat transfer structure, which comprises a spiral fin and a heat exchange sleeve, the heat exchange sleeve is sleeved on a heat exchange pipeline, the spiral fin is spirally arranged on the outer side of the heat exchange sleeve, and the spiral fin is composed of a plurality of groups of sheet fin unit structures. The spiral fins are integrally formed by heat dissipation transverse plates and guide inclined plates; a manufacturing method of an economizer fin of an enhanced heat transfer structure comprises the following steps that aluminum is adopted as a raw material, a heat exchange sleeve is cast through a die-casting technology, inserting grooves are evenly formed in the outer side wall of the heat exchange sleeve, and sheet-shaped fin units are inserted into the inserting grooves; the heat exchange pipe is sleeved with the heat exchange sleeve, the heat conduction extrusion groove is formed in the inner wall of the heat exchange sleeve, the liquid metal heat conduction agent is filled in the heat conduction extrusion groove, the heat conduction path between the heat exchange pipe and the heat exchange sleeve is increased, and heat resistance is effectively reduced. The contact area of the fins and the air is increased, and the efficiency of transferring heat from the fins to the air is improved.

Description

Technical Field

[0001] The present invention relates to the technical field related to economizers, and in particular to an economizer fin with an enhanced heat transfer structure and a manufacturing method thereof. Background Art

[0002] With the improvement of environmental protection requirements, in order to meet the environmental protection requirements of flue gas pollutant emissions, selective catalytic reduction technology (SCR) is configured during boiler denitrification transformation. Many companies have transformed the economizer structure from a plain tube type to a spiral fin tube type.

[0003] Although the modified spiral finned tube economizer has the advantages of good heat transfer and low dust accumulation, it also brings some problems. On the one hand, the difficulty of installation has increased significantly, and welding defects are prone to leakage in the early stage of operation; on the other hand, due to the addition of spiral fins, the gap between the tubes is relatively small. In the middle and late stages of the service life, the tubes are eroded and worn by high-temperature flue gas, resulting in serious thinning of the wall thickness and prone to leakage. These leakage failures will cause the boiler to be frequently shut down for maintenance, affecting the safety of boiler operation and economic efficiency. Summary of the invention

[0004] The object of the present invention is to provide an economizer fin with an enhanced heat transfer structure and a manufacturing method thereof to solve the problems raised in the above-mentioned background technology.

[0005] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: an economizer fin with an enhanced heat transfer structure, an economizer fin with an enhanced heat transfer structure, comprising a spiral fin and a heat exchange sleeve, the heat exchange sleeve is sleeved on the heat exchange pipe, and the spiral fins are spirally arranged on the outside of the heat exchange sleeve, the spiral fins are composed of multiple groups of sheet fin unit structures, the spiral fins are integrally composed of a heat dissipation cross plate and a guide inclined plate, and the heat dissipation cross plate is horizontally fixed on the heat exchange sleeve, and the guide inclined plate is obliquely fixed on the heat exchange sleeve, a heat conduction groove is opened on the inner wall of the heat exchange sleeve, and the heat conduction groove is filled with liquid metal thermal conductor.

[0006] Furthermore, the outer wall of the heat exchange sleeve is evenly provided with installation slots, and the sheet-like fin units are inserted in the installation slots, and ventilation gaps are arranged between adjacent sheet-like fin units.

[0007] Furthermore, the spiral fins and the heat exchange sleeves are both made of composite materials, and multiple groups of heat exchange sleeves are mounted on the same heat exchange pipe.

[0008] A method for manufacturing an economizer fin with an enhanced heat transfer structure comprises the following steps: Aluminum is used as the raw material, and the heat exchange sleeve is cast by die casting. During the die casting process, a mold is used to ensure that the heat exchange sleeve is in a hollow cylindrical shape, and its inner diameter is adapted to the outer diameter of the heat exchange pipe. Rectangular installation slots are evenly opened on its outer wall, and an annular heat conduction extrusion groove is opened on its inner wall; At the same time, the spiral fins are cast by die-casting process, so that the spiral fins are cast in one piece with the heat dissipation horizontal plate and the guide inclined plate; A heat-conducting extrusion groove is opened on the inner wall of the heat exchange sleeve, and the liquid metal heat conductor is filled in the heat-conducting extrusion groove: Use precision processing equipment to accurately process annular heat-conducting grooves on the inner wall of the heat exchange sleeve to ensure that its dimensional accuracy meets the design requirements; Slowly inject the liquid metal thermal conductor into the thermal extrusion groove through a dedicated filling device to ensure uniform filling without bubbles; Evenly open installation slots on the outer wall of the heat exchange sleeve, and insert the sheet-like fin units inside the installation slots, while ensuring that ventilation gaps are set between adjacent sheet-like fin units: Use CNC processing equipment to accurately process evenly distributed rectangular installation slots on the outer wall of the heat exchange sleeve; Insert the fin units one by one into the installation slots, and use a special positioning tool to ensure that the ventilation gaps between adjacent fin units are uniform; Put the cast heat exchange sleeve on the heat exchange pipe, and put multiple sets of heat exchange sleeves on the same heat exchange pipe, then fix the spiral fins horizontally on the heat exchange sleeve through its heat dissipation cross plate, and fix the guide inclined plate on the heat exchange sleeve obliquely: Put the heat exchange sleeve on the surface treated heat exchange pipe to ensure that the two fit tightly; Install multiple sets of heat exchange sleeves on the same heat exchange pipe according to design requirements, and fix them on the heat exchange pipe by welding or mechanical connection; The heat dissipation horizontal plate of the spiral fin is fixed together with the heat exchange sleeve horizontally by bolt connection or welding, and the guide inclined plate is fixed together with the heat exchange sleeve by welding or other appropriate methods.

[0009] Furthermore, when casting the heat exchange sleeve, the manufacturing process of the slot on its outer wall is further optimized; first, when designing the mold of the slot, high-precision CNC processing technology is used to ensure that the dimensional accuracy of the slot is within ±0.05mm; during the die-casting process, the die-casting temperature is strictly controlled between 620℃-650℃, and this temperature range can ensure the fluidity and molding quality of the aluminum material; at the same time, after the die-casting is completed, the slot is subjected to secondary processing, and the inner wall of the slot is ground using precision grinding equipment to make its surface roughness reach below Ra0.8, so as to better ensure the tightness and stability of the sheet fin unit after insertion; For the manufacture of thermal extrusion grooves, a combination of laser cutting and electrospark machining is used when precision machining equipment is used. The laser cutting technology is first used to cut the approximate shape of the thermal extrusion groove, and then the electrospark machining is used to finely trim it to ensure the dimensional accuracy and surface quality of the thermal extrusion groove. This combined machining method can improve the machining accuracy of the thermal extrusion groove, so that it can better achieve heat transfer when filled with liquid metal thermal conductive agent. When filling the liquid metal thermal conductor, a flow monitoring device and a temperature control device are installed on the filling equipment; the flow monitoring device can monitor the injection flow of the liquid metal thermal conductor in real time to ensure that the injection speed is uniform and meets the design requirements, and avoid uneven distribution of the thermal conductor due to too fast or too slow injection speed; the temperature control device can control the temperature of the thermal conductor within a suitable range to prevent the thermal conductivity and filling effect from being affected by too high or too low temperature; at the same time, after the filling is completed, the thermal extrusion groove is sealed with a high-performance sealant to prevent leakage of the thermal conductor and ensure its long-term stable thermal conductivity.

[0010] Furthermore, when casting the spiral fins, the integrated casting process of the heat dissipation horizontal plate and the guide ramp plate is improved; in terms of mold design, 3D printing technology is used to make a mold prototype, and then the final mold is optimized and manufactured based on the prototype; this method can more accurately design the shape and structure of the heat dissipation horizontal plate and the guide ramp plate to better meet the requirements of heat transfer and air flow; in terms of casting materials, a certain proportion of rare earth elements, cerium and lanthanum, are added to the aluminum material, and the addition amounts are 0.5%-1% and 0.3%-0.8% respectively; these rare earth elements can refine the grain structure of the aluminum material, improve its strength and heat resistance, so that the spiral fins can work better in a high temperature environment and have a longer service life; When fixing the spiral fins on the heat exchange sleeve, the fixing method of the heat dissipation cross plate and the heat exchange sleeve is optimized; a new bolt connection method is adopted, the bolts are made of high-strength titanium alloy material, and the head thereof is designed in a special shape, which can better cooperate with the heat dissipation cross plate and the heat exchange sleeve; during the bolt installation process, holes are first drilled at corresponding positions on the heat dissipation cross plate and the heat exchange sleeve, and the drilling accuracy is controlled within ±0.03mm, and then a special installation tool is used to install the bolts in place, and the installation torque is controlled between 20-30N·m; this precise installation method can ensure the tightness and stability of the connection between the heat dissipation cross plate and the heat exchange sleeve, and improve the heat transfer efficiency; at the same time, for the fixation of the guide inclined plate and the heat exchange sleeve, a new welding process is adopted, and the use of laser welding technology can accurately control the welding energy and welding position, so that the welding between the guide inclined plate and the heat exchange sleeve is firm and defect-free, ensuring that the air can flow smoothly around the spiral fins.

[0011] Furthermore, in the process of putting the heat exchange sleeve on the heat exchange pipe, the surface treatment process of the heat exchange pipe is improved; first, the heat exchange pipe is chemically cleaned using a specially formulated acid cleaning solution, the main components of which include hydrochloric acid, nitric acid and corrosion inhibitor, the concentrations of hydrochloric acid and nitric acid are 5%-10% and 3%-8% respectively, and the content of the corrosion inhibitor is 0.5%-1.5%; this cleaning solution can effectively remove impurities such as oil, rust and scale on the surface of the heat exchange pipe, and provide a clean surface for the subsequent casing process; then, the surface of the cleaned heat exchange pipe is passivated using a passivation solution containing chromate, and the concentration of chromate is 2%-5%; the passivation treatment can form a dense passivation film on the surface of the heat exchange pipe, improve its corrosion resistance, and prevent the heat transfer efficiency from being affected by corrosion during use; When multiple sets of heat exchange sleeves are installed on the same heat exchange pipe, the installation sequence and spacing are optimized; first, the heat exchange sleeves are installed in sequence from one end to the other, and during the installation process, a special installation tool is used, which can accurately control the relative position of the heat exchange sleeves and the heat exchange pipe to ensure accurate installation; the spacing between adjacent heat exchange sleeves is designed according to the heat exchange requirements and air flow characteristics, and the spacing is controlled between 10-20mm; this spacing can ensure that the air can flow smoothly between adjacent heat exchange sleeves, while also meeting the requirements of heat transfer and improving the overall heat transfer efficiency of the economizer.

[0012] Furthermore, in the manufacturing process of the sheet-like fin unit, its material and structure are optimized; in terms of materials, a new type of composite material is used, which is composed of carbon fiber and aluminum alloy, and the content of carbon fiber is 10%-20%; carbon fiber has high strength, low density and good thermal conductivity, and combined with aluminum alloy can improve the overall performance of the sheet-like fin unit; in terms of structure, the sheet-like fin unit is designed as a double-layer structure, the upper layer is a heat dissipation layer, and the lower layer is a support layer; the heat dissipation layer adopts a material with a microchannel structure, which can increase the contact area between air and fins and improve heat dissipation efficiency; the support layer adopts a high-strength aluminum alloy material, which can provide sufficient support for the sheet-like fin unit to prevent its deformation; When inserting the sheet-like fin unit into the installation slot, the insertion process is controlled; first, a guide structure is designed at the insertion end of the sheet-like fin unit, and the guide structure can accurately match with the entrance of the installation slot to facilitate insertion; during the insertion process, a special insertion tool is used, and the tool can apply a uniform insertion force to prevent the sheet-like fin unit from being damaged or not inserted properly due to excessive or insufficient insertion force; at the same time, after the insertion is completed, the sheet-like fin unit is positioned and detected, and a high-precision laser positioning system is used to detect whether the sheet-like fin unit is accurately inserted into the installation slot and whether it is kept in the correct position.

[0013] Furthermore, in terms of the selection of liquid metal thermal conductors, the composition and performance of the liquid metal alloy are optimized; a liquid metal alloy composed of gallium, indium and tin is selected as the thermal conductor, and the composition ratio is gallium: indium: tin = 60%: 20%: 20%; the liquid metal alloy with this composition ratio has a higher thermal conductivity coefficient, which can reach 80-100W / (m·K), and has better thermal conductivity than traditional thermal conductors; at the same time, it can exist stably for a long time in the thermal extrusion groove without chemical reaction or precipitation; Before filling the liquid metal thermal conductor, the thermal extrusion groove is pretreated; first, the thermal extrusion groove is vacuum treated to evacuate the air in the thermal extrusion groove to prevent the air from mixing into the liquid metal thermal conductor and affecting its thermal conductivity; then, the thermal extrusion groove is preheated to 50-60°C, which makes it easier to fill the liquid metal thermal conductor and improves the uniformity of its filling; during the filling process, a dynamic filling method is adopted, that is, while filling the liquid metal thermal conductor, the thermal extrusion groove is vibrated at a vibration frequency of 20-30Hz; this dynamic filling method can further improve the filling uniformity of the liquid metal thermal conductor and ensure its uniform distribution in the thermal extrusion groove.

[0014] Furthermore, after the entire manufacturing process is completed, the quality of the manufactured economizer fins is inspected and optimized; first, the appearance of the economizer fins is inspected to check whether there are defects such as cracks, deformations, holes, etc., and a high-precision optical detection equipment is used for detection with a detection accuracy of 0.01mm; for the defects found, they are repaired or scrapped according to the type and severity of the defects; then, the heat transfer performance of the economizer fins is tested to simulate the actual working environment and measure its parameters such as heat transfer coefficient and thermal resistance; based on the test results, the economizer fins are optimized and adjusted. If the heat transfer coefficient is lower than the design requirement, the liquid metal thermal conductor in the heat extrusion groove is supplemented or replaced, or the structure and position of the sheet fin unit are adjusted; if the thermal resistance is too high, the shape and fixing method of the spiral fins are adjusted, or the coordination between the heat exchange sleeve and the heat exchange pipe is optimized to improve the heat transfer performance of the economizer fins.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: the heat exchange sleeve is sleeved on the heat exchange pipe, and its inner wall is provided with a heat conduction groove and filled with liquid metal heat conductor, which increases the heat conduction path between the heat exchange pipe and the heat exchange sleeve, and effectively reduces the thermal resistance. At the same time, the outer wall of the heat exchange sleeve is evenly provided with an installation slot and a sheet-shaped fin unit is inserted, and the spiral fin is integrally formed by a heat dissipation horizontal plate and a guide inclined plate and fixed on the heat exchange sleeve, which greatly increases the contact area between the fin and the air and improves the efficiency of heat transfer from the fin to the air.

[0016] The spiral fins and heat exchange sleeves are both cast from aluminum, which has good thermal conductivity. When casting the spiral fins, a certain proportion of rare earth elements is added to the aluminum, which further refines the grain structure, improves its strength and heat resistance, and helps to better transfer heat. In addition, the use of liquid metal thermal conductors and the optimization of their composition and properties also significantly improve the overall heat transfer efficiency.

[0017] During the manufacturing process, the manufacturing process of each component is strictly controlled and optimized. For example, when casting the heat exchange sleeve, the manufacturing process of the slot is optimized, and the dimensional accuracy of the slot is guaranteed to be within ±0.05mm through high-precision CNC machining technology, the die-casting temperature is controlled between 620℃-650℃, and the slot is ground twice to make its surface roughness reach below Ra0.8, ensuring the tightness and stability of the fin unit after insertion. The heat-conducting extrusion groove is combined with laser cutting and electric spark machining to improve the machining accuracy and ensure its good thermal conductivity after filling with thermal conductive agent. These precise manufacturing processes ensure the quality and matching accuracy of each component, thereby improving the stability of the overall structure.

[0018] In the connection between the heat exchange sleeve and the heat exchange pipe, the heat exchange pipe is surface treated, the relative position is controlled by special tools during the assembly process, and the spacing between adjacent heat exchange sleeves is optimized to ensure the stable installation of the heat exchange sleeve on the heat exchange pipe and further improve the reliability of the entire structure.

[0019] In the manufacturing process of the sheet fin unit, a composite material composed of carbon fiber and aluminum alloy is used, and it is designed as a double-layer structure. The upper heat dissipation layer is made of a material with a microchannel structure, and the lower support layer is made of a high-strength aluminum alloy, which improves the overall performance of the sheet fin unit and enhances its wear resistance. At the same time, the surface of the heat exchange pipe is passivated to form a dense passivation film, which improves its corrosion resistance. These designs can effectively reduce component damage caused by wear and corrosion during use, thereby extending the service life of the economizer fins.

[0020] During the filling process of the liquid metal thermal conductor, the thermal extrusion groove is pretreated and a dynamic filling method is used to ensure the uniform distribution and long-term stable existence of the thermal conductor in the thermal extrusion groove, avoiding local overheating or performance degradation caused by uneven distribution or precipitation of the thermal conductor. In addition, during operation, by optimizing the denitrification process, the generation of ammonium bisulfate and the corrosion of the economizer tube wall can be reduced, further extending the service life of the economizer. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the existing economizer pipe fins; Figure 2 A schematic diagram of the economizer pipe fin of the structure of the present invention; Figure 3 It is a schematic diagram of the structural fin unit of the present invention; Figure 4 It is a cross-sectional schematic diagram of the pipe fin structure of the present invention; Figure 5 Schematic diagram of the heat exchange sleeve of the present invention.

[0022] In the figure: 1, heat exchange pipe; 2, spiral fin; 21, heat dissipation horizontal plate; 22, guide inclined plate; 3, heat exchange sleeve; 31, heat conduction extrusion groove; 32, installation slot. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] See also Figure 1-5 The present invention provides a technical solution: a specific implementation method of an economizer fin with an enhanced heat transfer structure and a manufacturing method thereof: 1. Raw materials preparation In the present invention, the heat exchange sleeve and the spiral fins are both made of aluminum as the base material. Aluminum with high purity and good thermal conductivity is selected, and its purity is required to reach more than 99%. When purchasing aluminum, its chemical composition should be strictly tested to ensure that it meets the design requirements. The content of impurity elements should be tested, the iron content should be controlled below 0.2%, and the silicon content should be controlled below 0.1% to ensure the thermal conductivity and machinability of the aluminum.

[0025] The physical properties of aluminum should also be tested, including its density, hardness and thermal expansion coefficient. The density of aluminum should be around 2.7g / cm³, the hardness should meet the corresponding standards (such as Brinell hardness HB between 30-50), and the thermal expansion coefficient should be 23×10 -6 / ℃, so as to ensure that the performance of aluminum is stable in different temperature environments and will not be deformed or damaged due to thermal expansion and contraction.

[0026] Liquid metal thermal conductor composition preparation: For liquid metal thermal conductor, gallium: indium: tin = 60%: 20%: 20% ratio is used for configuration. First, high-purity gallium, indium and tin raw materials should be purchased. The purity of gallium should be above 99.99%, the purity of indium should be above 99.9%, and the purity of tin should be above 99.8%. During the configuration process, a high-precision electronic scale should be used for weighing to ensure that the proportions of each component are accurate.

[0027] Preparation of sheet fin unit materials: For the composite materials of sheet fin units, the ratio of carbon fiber and aluminum alloy should be strictly controlled. The content of carbon fiber is 10%-20%. When selecting carbon fiber, high-strength, high-modulus and good thermal conductivity carbon fiber should be selected. Its tensile strength should be above 3000MPa and its modulus should be above 200GPa. The selection of aluminum alloy should match the overall structure, and its performance should meet the design requirements, such as hardness, thermal conductivity, etc. At the same time, when preparing composite materials, advanced composite processes, such as fiber winding, molding and other processes, should be used to ensure that the carbon fiber and aluminum alloy are tightly bonded and there will be no delamination.

[0028] 2. Heat exchange casing manufacturing 1. Mould design and manufacturing The die-casting mold for the heat exchange sleeve is designed with high-precision CNC machining technology. When designing the mold part of the slot, it is necessary to ensure that the dimensional accuracy of the slot is within ±0.05mm. The mold is precisely designed using computer-aided design software, and then processed and manufactured using a CNC machining center. During the processing, the processing accuracy must be monitored in real time, such as using a three-coordinate measuring instrument to measure the size of the processed mold to ensure that it meets the design requirements.

[0029] For the die part of the heat-conducting extrusion groove, its annular structure and dimensional accuracy requirements must be taken into consideration. The die is manufactured by combining EDM and wire cutting. First, wire cutting is used to machine the rough shape, and then EDM is used for fine finishing to ensure that the dimensional accuracy of the die of the heat-conducting extrusion groove is within ±0.02mm.

[0030] 2. Die Casting Process Put the prepared aluminum material into the die casting machine for die casting. During the die casting process, the die casting temperature is strictly controlled between 620℃-650℃. The die casting temperature is monitored in real time by the temperature sensor. When the temperature deviates from the set range, the control system of the die casting machine will automatically adjust the heating power to ensure temperature stability. At the same time, the die casting pressure should be controlled within a suitable range. According to the characteristics of the aluminum material and the structure of the mold, the die casting pressure is generally controlled between 50-80MPa to ensure that the aluminum material can fully fill all parts of the mold and form a good quality heat exchange sleeve.

[0031] During the die-casting process, attention should be paid to the exhaust of the mold. Reasonable exhaust holes should be set on the mold, and the size and position of the exhaust holes should be optimized according to the structure of the mold and the die-casting process. Generally speaking, the diameter of the exhaust holes is between 0.5-1mm, and the positions should be distributed in the key parts of the mold, such as the installation slot and the heat conduction extrusion slot, to ensure that the air in the mold can be discharged smoothly during the die-casting process to avoid defects such as pores.

[0032] 3. Secondary processing After die casting, the heat exchange sleeve is processed for secondary processing. First, the inner wall of the installation slot is ground using precision grinding equipment to make its surface roughness reach below Ra0.8. During the grinding process, the grinding speed and pressure must be controlled. The grinding speed is generally controlled between 50-100mm / min, and the pressure is controlled between 1-3N / cm² to ensure the quality and efficiency of the grinding.

[0033] For the thermal extrusion groove, precision processing equipment is used to process it again to ensure that its dimensional accuracy meets the design requirements. A combination of laser cutting and electrospark machining is used. First, the laser cutting technology is used to cut the approximate shape of the thermal extrusion groove, and then electrospark machining is used to fine-tune it. During the laser cutting process, the laser power and cutting speed must be controlled. The laser power is generally controlled between 100-300W, and the cutting speed is controlled between 10-30mm / s. During the electrospark machining process, the discharge parameters, such as discharge current, discharge voltage and discharge frequency, must be controlled. The discharge current is generally controlled between 1-5A, the discharge voltage is controlled between 80-120V, and the discharge frequency is controlled between 10-30kHz to ensure the processing accuracy and surface quality of the thermal extrusion groove.

[0034] 3. Spiral fin manufacturing 1. Mould design and manufacturing In terms of mold design, 3D printing technology is used to make mold prototypes. First, according to the design requirements of the spiral fins, the mold is designed using 3D design software, and then the designed model file is input into the 3D printer for printing. During the printing process, it is necessary to select suitable 3D printing materials, such as photosensitive resin, which has good molding performance and precision. After printing, the mold prototype is inspected and optimized, and the mold is adjusted and the final mold is manufactured according to the inspection results.

[0035] When manufacturing the final mold, the requirement of integral casting of the heat dissipation horizontal plate and the guide ramp plate must be taken into consideration. The mold is processed using high-precision CNC machining technology to ensure that the dimensional accuracy of the mold is within ±0.03mm. The mold is precisely designed using computer-aided design software and then processed and manufactured using a CNC machining center. During the processing, the processing accuracy must be monitored in real time, such as using a three-coordinate measuring instrument to measure the size of the processed mold to ensure that it meets the design requirements.

[0036] 2. Casting process Put the prepared aluminum material into the casting furnace for casting. During the casting process, a certain proportion of rare earth elements cerium and lanthanum should be added to the aluminum material. The amount of cerium added is 0.5%-1%, and the amount of lanthanum added is 0.3%-0.8%. The rare earth elements are evenly dispersed in the aluminum material through a stirring device, and then cast. During the casting process, the casting temperature should be controlled between 650℃-700℃ and the casting pressure should be between 40-60MPa to ensure that the aluminum material can fully fill all parts of the mold and form a spiral fin of good quality.

[0037] During the casting process, attention should be paid to the exhaust of the mold. Reasonable exhaust holes should be set on the mold. The size of the exhaust holes should be distributed in the key parts of the mold, such as the joint of the heat dissipation horizontal plate and the guide inclined plate, to ensure that the obscure gas in the mold can be discharged smoothly during the casting process to avoid defects such as pores.

[0038] After casting, the performance of the spiral fins is improved due to the addition of rare earth elements. Rare earth elements can refine the grain structure of aluminum and improve its strength and heat resistance. Observing the grain structure of the spiral fins through a metallographic microscope, it can be seen that the grains are significantly refined, and the average grain size is reduced from the original 50μm to less than 20μm. At the same time, the mechanical properties of the spiral fins were tested, and their tensile strength increased by 20%-30%, and the heat resistance was also significantly improved. In a high temperature environment, the deformation of the spiral fins was significantly reduced.

[0039] 4. Heat conduction groove processing 1. Preprocessing Before filling the liquid metal thermal conductor, the thermal extrusion groove is pre-treated. First, the thermal extrusion groove is vacuum treated to evacuate the air in the thermal extrusion groove. Use a vacuum pump to evacuate the thermal extrusion groove. The evacuation time is generally controlled between 10-20 minutes until the pressure in the thermal extrusion groove reaches 10 - ³Pa or less to prevent air from mixing into the liquid metal thermal conductor and affecting its thermal conductivity.

[0040] Then, the heat-conducting extrusion groove is preheated to 50-60°C. The heat-conducting extrusion groove is heated by a heating device. During the heating process, the heating speed should be controlled. The heating speed is generally controlled between 1-3°C / min to ensure that the heat-conducting extrusion groove can be evenly heated and improve the filling uniformity of the liquid metal thermal conductor.

[0041] 2. Filling process The prepared liquid metal thermal conductor is slowly injected into the thermal extrusion groove through a dedicated filling device. A flow monitoring device and a temperature control device are installed on the filling device. The flow monitoring device can monitor the injection flow of the liquid metal thermal conductor in real time to ensure that its injection speed is uniform and meets the design requirements, and avoid uneven distribution of the thermal conductor due to too fast or too slow injection speed. The temperature control device can control the temperature of the thermal conductor within a suitable range to prevent the thermal conductivity and filling effect from being affected by too high or too low temperature.

[0042] During the filling process, a dynamic filling method is used, that is, the thermal extrusion groove is vibrated while the liquid metal thermal conductor is filled. The vibration frequency is 20-30Hz. Vibrating the thermal extrusion groove by the vibration device can further improve the filling uniformity of the liquid metal thermal conductor and ensure its uniform distribution in the thermal extrusion groove.

[0043] 3. Sealing treatment After filling, seal the thermal extrusion groove. Use high-performance sealant to seal it. Choose a suitable sealant, such as silicone sealant, which has good sealing performance and temperature resistance. When applying the sealant, make sure that the sealant is evenly applied to cover the entire opening of the thermal extrusion groove to prevent leakage of the thermal conductor and ensure its long-term stable thermal conductivity.

[0044] 5. Manufacturing of sheet fin units 1. Material Composite For the composite material of the sheet fin unit, the carbon fiber and the aluminum alloy are compounded according to the ratio. First, the carbon fiber and the aluminum alloy are pretreated separately. The carbon fiber is surface treated, such as using chemical vapor deposition technology to deposit a metal coating on the surface of the carbon fiber to improve the bonding force between the carbon fiber and the aluminum alloy. The aluminum alloy is surface cleaned and pretreated, such as using pickling and other methods to remove impurities such as oil and scale on the surface.

[0045] Then, the carbon fiber and aluminum alloy are compounded together using advanced composite technology. For example, the fiber winding process is used to wind the carbon fiber around the aluminum alloy core rod according to the design requirements, and then the curing process is carried out. The curing temperature is generally controlled between 150-200℃, and the curing time is generally controlled between 2-4 hours to ensure that the carbon fiber and aluminum alloy are tightly bonded without delamination.

[0046] The fin unit is designed as a double-layer structure, with the upper layer being the heat dissipation layer and the lower layer being the support layer. The heat dissipation layer is made of a material with a microchannel structure, which can increase the contact area between the air and the fins and improve the heat dissipation efficiency. The support layer is made of a high-strength aluminum alloy material, which can provide sufficient support for the fin unit to prevent its deformation.

[0047] In the manufacturing process, the support layer is first manufactured. The shape of the support layer is manufactured by using aluminum alloy sheet through stamping and other processes, and then the heat dissipation layer is manufactured on the support layer. For the manufacture of the heat dissipation layer, micro-manufacturing technology, such as photolithography, etching and other technologies, is used to manufacture a micro-channel structure on the support layer. In the manufacturing process, the manufacturing accuracy must be controlled, such as the dimensional accuracy of the micro-channel should be controlled within ±0.02mm to ensure the good performance of the heat dissipation layer.

[0048] 6. Fin and sleeve assembly 1. Spiral fin fixation Fix the cast spiral fins on the heat exchange sleeve. A new type of bolt connection method is used to connect the heat dissipation horizontal plate and the heat exchange sleeve. The bolts are made of high-strength titanium alloy material, and their heads are designed in a special shape to better match the heat dissipation horizontal plate and the heat exchange sleeve. During the bolt installation process, first drill holes at the corresponding positions on the heat dissipation horizontal plate and the heat exchange sleeve, and the drilling accuracy is controlled within ±0.03mm. Then use a special installation tool to install the bolts in place, and the installation torque is controlled between 20-30N·m.

[0049] For the connection between the guide ramp plate and the heat exchange sleeve, laser welding technology is used, which can accurately control the welding energy and welding position, so that the welding between the guide ramp plate and the heat exchange sleeve is firm and defect-free, ensuring that the air can flow smoothly around the spiral fins.

[0050] 2. Insertion of the sheet fin unit Installation slots are evenly opened on the outer wall of the heat exchange sleeve, and the flaky fin units are inserted inside the installation slots, while ensuring that ventilation gaps are set between adjacent flaky fin units. Use CNC machining equipment to accurately process uniformly distributed rectangular installation slots on the outer wall of the heat exchange sleeve. Insert the flaky fin units into the installation slots one by one, and use special positioning tooling to ensure that the ventilation gaps between adjacent flaky fin units are uniform. The guide structure can accurately match the entrance of the installation slot for easy insertion. During the insertion process, a uniform insertion force is applied to prevent the flaky fin unit from being damaged or not inserted properly due to excessive or insufficient insertion force. At the same time, after the insertion is completed, the flaky fin unit is positioned and detected to detect whether the flaky fin unit is accurately inserted into the installation slot and whether it is kept in the correct position.

[0051] 7. Assembly of heat exchange casing and heat exchange pipe 1. Surface treatment of heat exchange pipes Before the heat exchange sleeve is put on the heat exchange pipe, the heat exchange pipe is surface treated. First, the heat exchange pipe is chemically cleaned using a specially formulated acid cleaning solution, the main components of which include hydrochloric acid, nitric acid and corrosion inhibitor. The concentrations of hydrochloric acid and nitric acid are 5%-10% and 3%-8% respectively, and the content of corrosion inhibitor is 0.5%-1.5%. This cleaning solution can effectively remove impurities such as oil, rust and oxide scale on the surface of the heat exchange pipe, providing a clean surface for the subsequent set process.

[0052] Then, the cleaned heat exchange pipe is subjected to surface passivation treatment, using a passivation solution containing chromate, with a chromate concentration of 2%-5%. The passivation treatment can form a dense passivation film on the surface of the heat exchange pipe, improve its corrosion resistance, and prevent corrosion from affecting the heat transfer efficiency during use.

[0053] 2. Package process Install the heat exchange sleeve on the surface treated heat exchange pipe to ensure that the two fit tightly. Install multiple sets of heat exchange sleeves on the same heat exchange pipe according to the design requirements and place them in place by welding or mechanical connection. During the installation process, a special installation tool is used, which can accurately control the relative position of the heat exchange sleeve and the heat exchange pipe to ensure accurate installation. The spacing between adjacent heat exchange sleeves is designed according to the heat exchange requirements and air flow characteristics, and the spacing is controlled between 10-20mm. This spacing can ensure that the air can flow smoothly between adjacent heat exchange sleeves, and at the same time it can also meet the requirements of heat transfer and improve the overall heat transfer efficiency of the economizer.

[0054] 8. Quality Inspection and Optimization 1. Appearance inspection After the entire manufacturing process is completed, the economizer fins are quality tested and optimized. First, the appearance of the economizer fins is checked for defects such as cracks, deformations, holes, etc. A high-precision optical inspection device is used for inspection with an inspection accuracy of 0.01mm. For defects found, they are repaired or scrapped according to the type and severity of the defects.

[0055] 2. Heat transfer performance test The heat transfer performance of the economizer fins is tested to simulate the actual working environment and measure parameters such as heat transfer coefficient and thermal resistance. The economizer fins are tested under different temperature and flow conditions. According to the test results, the economizer fins are optimized and adjusted. If the heat transfer coefficient is lower than the design requirements, the liquid metal thermal conductor in the heat extrusion groove is supplemented or replaced, or the role of the sheet fin unit is to be specifically described through this detailed implementation method. Each link of the economizer fin and the manufacturing method of the present invention is ensured to achieve the expected beneficial effects, improve the heat transfer performance, structural stability and reliability of the economizer, extend its service life, and facilitate manufacturing and installation.

[0056] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An economizer fin with an enhanced heat transfer structure, comprising a spiral fin (2) and a heat exchange sleeve (3), characterized in that: The heat exchange sleeve (3) is sleeved on the heat exchange pipe (1), and spiral fins (2) are spirally arranged on the outer side of the heat exchange sleeve (3), the spiral fins (2) are composed of a plurality of groups of sheet-like fin unit structures, the spiral fins (2) are integrally composed of a heat dissipation transverse plate (21) and a guide inclined plate (22), the heat dissipation transverse plate (21) is horizontally fixed on the heat exchange sleeve (3), and the guide inclined plate (22) is obliquely fixed on the heat exchange sleeve (3), the inner wall of the heat exchange sleeve (3) is provided with a heat conduction groove (31), and the heat conduction groove (31) is filled with a liquid metal heat conductor.

2. The economizer fin with enhanced heat transfer structure according to claim 1, characterized in that: The outer wall of the heat exchange sleeve (3) is evenly provided with installation slots (32), and sheet-like fin units are inserted into the installation slots (32), while ventilation gaps are provided between adjacent sheet-like fin units.

3. The economizer fin with enhanced heat transfer structure according to claim 1, characterized in that: The spiral fins (2) and the heat exchange sleeves (3) are both made of composite materials, and a plurality of sets of heat exchange sleeves (3) are mounted on the same heat exchange pipe (1).

4. A method for manufacturing an economizer fin with an enhanced heat transfer structure according to any one of claims 1 to 3, characterized in that: The following steps are involved: Aluminum is used as a raw material and a heat exchange sleeve (3) is cast by a die-casting process. During the die-casting process, a mold is used to ensure that the heat exchange sleeve (3) is in the shape of a hollow cylinder, the inner diameter of which matches the outer diameter of the heat exchange pipe (1), and rectangular installation slots (32) are evenly opened on the outer wall thereof, and an annular heat conduction extrusion groove (31) is opened on the inner wall thereof; At the same time, the spiral fin (2) is cast by a die-casting process, so that the spiral fin (2) is integrally cast by using the heat dissipation horizontal plate (21) and the guide inclined plate (22); A heat-conducting extrusion groove (31) is provided on the inner wall of the heat exchange sleeve (3), and a liquid metal heat-conducting agent is filled inside the heat-conducting extrusion groove (31): Using precision processing equipment to accurately process an annular heat-conducting extrusion groove (31) on the inner wall of the heat exchange sleeve (3) to ensure that its dimensional accuracy meets the design requirements; The liquid metal thermal conductor is slowly injected into the thermal extrusion groove (31) through a dedicated filling device to ensure that the filling is uniform and free of bubbles; Evenly opening installation slots (32) on the outer wall of the heat exchange sleeve (3), and inserting sheet-like fin units inside the installation slots (32), while ensuring that ventilation gaps are provided between adjacent sheet-like fin units: using CNC processing equipment to accurately process evenly distributed rectangular installation slots (32) on the outer wall of the heat exchange sleeve (3); Inserting the sheet-like fin units into the installation slots (32) one by one, and ensuring that the ventilation gaps between adjacent sheet-like fin units are uniform by using a dedicated positioning tool; The cast heat exchange sleeve (3) is mounted on the heat exchange pipe (1), and multiple sets of heat exchange sleeves (3) are mounted on the same heat exchange pipe (1). The spiral fins (2) are then fixed horizontally on the heat exchange sleeve (3) through their heat dissipation cross plates (21), and the guide inclined plates (22) are fixed obliquely on the heat exchange sleeve (3): Put the heat exchange sleeve (3) onto the heat exchange pipe (1) that has undergone surface treatment, and ensure that the two are tightly fitted; Mounting a plurality of sets of heat exchange sleeves (3) on the same heat exchange pipe (1) according to design requirements, and fixing them on the heat exchange pipe (1) by welding or mechanical connection; The heat dissipation horizontal plate (21) of the spiral fin (2) and the heat exchange sleeve (3) are fixed together horizontally by bolt connection or welding, and the guide inclined plate (22) and the heat exchange sleeve (3) are fixed together obliquely by welding or other suitable methods.

5. The method for manufacturing economizer fins with enhanced heat transfer structure according to claim 4, characterized in that: When casting the heat exchange sleeve (3), the manufacturing process of the slot (32) on the outer wall thereof is further optimized; first, when designing the mold of the slot (32), high-precision CNC machining technology is used to ensure that the dimensional accuracy of the slot (32) is within ±0.05 mm; during the die-casting process, the die-casting temperature is strictly controlled between 620° C. and 650° C. This temperature range can ensure the fluidity and molding quality of the aluminum material to be optimal; at the same time, after the die-casting is completed, the slot (32) is subjected to secondary processing, and the inner wall of the slot (32) is ground using precision grinding equipment to achieve a surface roughness of less than Ra0.8, so that the tightness and stability of the sheet-like fin unit after insertion can be better ensured; For the manufacture of the heat-conducting extruded groove (31), a combination of laser cutting and electric spark machining is used when precision machining equipment is used for machining; the laser cutting technology is first used to cut the approximate shape of the heat-conducting extruded groove (31), and then the electric spark machining is used to finely trim it to ensure the dimensional accuracy and surface quality of the heat-conducting extruded groove (31); this combined machining method can improve the machining accuracy of the heat-conducting extruded groove (31), so that it can better achieve heat transfer when the liquid metal thermal conductive agent is filled; When filling the liquid metal thermal conductor, a flow monitoring device and a temperature control device are installed on the filling equipment; the flow monitoring device can monitor the injection flow of the liquid metal thermal conductor in real time to ensure that its injection speed is uniform and meets the design requirements, and avoid uneven distribution of the thermal conductor due to too fast or too slow injection speed; the temperature control device can control the temperature of the thermal conductor within a suitable range to prevent the thermal conductivity and filling effect from being affected by too high or too low temperature; at the same time, after the filling is completed, the thermal extrusion groove (31) is sealed with a high-performance sealant to prevent leakage of the thermal conductor and ensure its long-term stable thermal conductivity.

6. The method for manufacturing economizer fins with enhanced heat transfer structure according to claim 4, characterized in that: When casting the spiral fins (2), the integral casting process of the heat dissipation horizontal plate (21) and the guide inclined plate (22) is improved; in terms of mold design, a mold prototype is made using 3D printing technology, and then the final mold is optimized and manufactured based on the prototype; This method can more accurately design the shape and structure of the heat dissipation horizontal plate (21) and the guide inclined plate (22), so that they can better meet the requirements of heat transfer and air flow. In terms of casting materials, a certain proportion of rare earth elements, cerium (Ce) and lanthanum (La), are added to the aluminum material, and the addition amounts are 0.5%-1% and 0.3%-0.8% respectively. These rare earth elements can refine the grain structure of the aluminum material, improve its strength and heat resistance, so that the spiral fins (2) can work better in a high temperature environment and have a longer service life. When the spiral fins (2) are fixed to the heat exchange sleeve (3), the fixing method of the heat dissipation horizontal plate (21) and the heat exchange sleeve (3) is optimized; a new bolt connection method is adopted, the bolts are made of high-strength titanium alloy material, and the heads are designed to have a special shape so as to better match the heat dissipation horizontal plate (21) and the heat exchange sleeve (3); during the bolt installation process, holes are first drilled at corresponding positions on the heat dissipation horizontal plate (21) and the heat exchange sleeve (3), and the drilling accuracy is controlled within ±0.03 mm, and then the bolts are installed using a special installation tool. The heat exchange sleeve (3) is installed in place, and the installation torque is controlled between 20-30 N·m. This precise installation method can ensure the tightness and stability of the connection between the heat dissipation horizontal plate (21) and the heat exchange sleeve (3), thereby improving the heat transfer efficiency. At the same time, for the fixation of the guide inclined plate (22) and the heat exchange sleeve (3), a new welding process is adopted, using laser welding technology, which can accurately control the welding energy and welding position, so that the welding between the guide inclined plate (22) and the heat exchange sleeve (3) is firm and defect-free, thereby ensuring that the air can flow smoothly around the spiral fins (2).

7. The method for manufacturing economizer fins with enhanced heat transfer structure according to claim 4, characterized in that: During the process of sleeve-fitting the heat exchange sleeve (3) onto the heat exchange pipe (1), the surface treatment process of the heat exchange pipe (1) is improved; first, the heat exchange pipe (1) is chemically cleaned using a specially formulated acidic cleaning solution, the main components of which include hydrochloric acid, nitric acid and a corrosion inhibitor, the concentrations of hydrochloric acid and nitric acid being 5%-10% and 3%-8% respectively, and the content of the corrosion inhibitor being 0.5%-1.5%; the cleaning solution can effectively remove impurities such as oil, rust and scale on the surface of the heat exchange pipe (1), thereby providing a clean surface for the subsequent sleeve-fitting process; then, the cleaned heat exchange pipe (1) is subjected to a surface passivation treatment using a passivation solution containing chromate, the concentration of chromate being 2%-5%; the passivation treatment can form a dense passivation film on the surface of the heat exchange pipe (1), thereby improving its corrosion resistance and preventing the heat transfer efficiency from being affected by corrosion during use; When multiple sets of heat exchange sleeves (3) are mounted on the same heat exchange pipe (1), the mounting sequence and spacing are optimized; first, the heat exchange sleeves (3) are mounted in sequence from one end to the other end, and during the mounting process, a special mounting tool is used, which can accurately control the relative position of the heat exchange sleeves (3) and the heat exchange pipe (1) to ensure accurate mounting; the spacing between adjacent heat exchange sleeves (3) is designed according to the heat exchange requirements and air flow characteristics, and the spacing is controlled between 10 and 20 mm; this spacing can ensure that the air can flow smoothly between the adjacent heat exchange sleeves (3), and at the same time can also meet the requirements of heat transfer, thereby improving the overall heat transfer efficiency of the economizer.

8. The method for manufacturing economizer fins with enhanced heat transfer structure according to claim 4, characterized in that: During the manufacturing process of the sheet-like fin unit, its material and structure are optimized; in terms of materials, a new type of composite material is used, which is composed of carbon fiber and aluminum alloy, and the content of carbon fiber is 10%-20%; carbon fiber has high strength, low density and good thermal conductivity, and combined with aluminum alloy can improve the overall performance of the sheet-like fin unit; in terms of structure, the sheet-like fin unit is designed as a double-layer structure, the upper layer is the heat dissipation layer, and the lower layer is the support layer; the heat dissipation layer adopts a material with a microchannel structure, which can increase the contact area between air and fins and improve heat dissipation efficiency; the support layer adopts a high-strength aluminum alloy material, which can provide sufficient support for the sheet-like fin unit to prevent its deformation; When inserting the sheet-like fin unit into the installation slot (32), the insertion process is controlled; first, a guide structure is designed at the insertion end of the sheet-like fin unit, and the guide structure can accurately match the entrance of the installation slot (32) to facilitate insertion; during the insertion process, a special insertion tool is used, and the tool can apply a uniform insertion force to prevent the sheet-like fin unit from being damaged or not inserted properly due to excessive or insufficient insertion force; at the same time, after the insertion is completed, the sheet-like fin unit is positioned and detected, and a high-precision laser positioning system is used to detect whether the sheet-like fin unit is accurately inserted into the installation slot (32) and whether it is maintained in the correct position.

9. The method for manufacturing economizer fins with enhanced heat transfer structure according to claim 4, wherein: In terms of the selection of liquid metal thermal conductor, its composition and performance are optimized; a liquid metal alloy composed of gallium, indium and tin is selected as the thermal conductor, and its composition ratio is gallium: indium: tin = 60%: 20%: 20%; the liquid metal alloy with this composition ratio has a high thermal conductivity coefficient, which can reach 80-100W / (m·K), and has better thermal conductivity than traditional thermal conductors; at the same time, it can exist stably for a long time in the thermal extrusion groove (31) without chemical reaction or precipitation; Before filling the liquid metal thermal conductor, the thermally conductive extrusion groove (31) is pre-treated; first, the thermally conductive extrusion groove (31) is vacuum-treated to evacuate the air in the thermally conductive extrusion groove (31) to prevent the air from mixing into the liquid metal thermal conductor and affecting its thermal conductivity; Then, the heat-conducting extrusion groove (31) is preheated to 50-60° C. This temperature can make it easier to fill the liquid metal thermal conductor and can improve the uniformity of its filling. During the filling process, a dynamic filling method is adopted, that is, while filling the liquid metal thermal conductor, the heat-conducting extrusion groove (31) is vibrated at a vibration frequency of 20-30 Hz. This dynamic filling method can further improve the filling uniformity of the liquid metal thermal conductor and ensure that it is evenly distributed in the heat-conducting extrusion groove (31).

10. The method for manufacturing economizer fins with enhanced heat transfer structure according to claim 4, characterized in that: After the entire manufacturing process is completed, the economizer fins are quality tested and optimized. First, the appearance of the economizer fins is checked to see if there are any defects such as cracks, deformations, holes, etc. A high-precision optical inspection device is used for inspection with an inspection accuracy of 0.01mm. For the defects found, they are repaired or scrapped according to the type and severity of the defects. Then, the heat transfer performance of the economizer fins is tested to simulate the actual working environment and measure parameters such as the heat transfer coefficient and thermal resistance. According to the test results, the economizer fins are optimized and adjusted. If the heat transfer coefficient is lower than the design requirement, the liquid metal heat conductor in the heat transfer groove (31) is supplemented or replaced, or the structure and position of the sheet fin unit are adjusted. If the thermal resistance is too high, the shape and fixing method of the spiral fin (2) are adjusted, or the coordination between the heat exchange sleeve (3) and the heat exchange pipe (1) is optimized to improve the heat transfer performance of the economizer fins.

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