A fin based on a bionic lotus-honeycomb structure, a heat exchanger and a preparation method

Abstract

The application discloses a kind of based on bionic lotus-honeycomb structure finned tube heat exchanger device, including external frame and heat exchange unit, the external frame is used to be connected with other bionic fin;Heat exchange unit is located on the surface of bionic fin;The surface of bionic fin is divided into multiple micro-units;The micro-unit includes honeycomb structure frame and hydrophobic microcone array;Adjacent micro-units are abutted by honeycomb structure frame, and hydrophobic microcone array is arranged on the surface of bionic fin and located in the inside of honeycomb structure frame;Form hydrophobic microcone array-honeycomb composite structure.The application solves the problem of insufficient mechanical durability of traditional superhydrophobic coating, heat transfer efficiency attenuation through the cross-scale design of bionic honeycomb and lotus structure, realizes the synergistic promotion of heat transfer enhancement, self-cleaning and structural durability.

Description

Technical Field

[0001] This invention relates to the field of heat exchanger technology, and in particular to a fin, heat exchanger, and preparation method based on a biomimetic lotus leaf-honeycomb structure. Background Technology

[0002] Finned radiators, as commonly used heat exchange devices, are significantly affected by surface dust and water accumulation, as well as structural durability, in terms of heat transfer efficiency and long-term reliability. In existing technologies, dust accumulation and droplet adhesion on the fin surface easily create thermal resistance, leading to decreased heat dissipation efficiency. While traditional superhydrophobic coatings possess self-cleaning capabilities, their micro / nano structures lack sufficient mechanical strength, making them susceptible to damage under airflow or particle impact, and their hydrophobic properties degrade rapidly. A single structural design cannot simultaneously achieve hydrophobic self-cleaning, efficient heat transfer, and mechanical durability, limiting the application of radiators in complex environments. Therefore, how to combine biomimetic structures with engineering materials to construct finned surfaces with synergistic multi-performance characteristics is a pressing technical problem to be solved in this field. Summary of the Invention

[0003] The purpose of this invention is to address the problems existing in the background technology by proposing a finned tube heat exchanger based on a biomimetic lotus leaf-honeycomb structure. This is achieved by constructing a lotus leaf-inspired hydrophobic microcone array-honeycomb composite structure on the fin surface to realize a finned radiator with enhanced heat transfer, self-cleaning, and mechanical durability, thus solving the problems of rapid heat dissipation efficiency decay and high maintenance costs in existing technologies. This structure can be widely used in fields such as heat dissipation of electronic equipment, automotive engine cooling, and thermal management of power machinery.

[0004] The technical solution of the present invention, the first aspect of the present invention provides a biomimetic fin based on a biomimetic lotus leaf-honeycomb structure, including an outer frame and a heat exchange unit, wherein the outer frame is used to connect with other biomimetic fins 1; The heat exchange unit is located on the surface of the biomimetic fins; The surface of the biomimetic fins is divided into multiple micro-units; The micro-unit includes a honeycomb structural frame and a hydrophobic micro-cone array; adjacent micro-units abut against each other through the honeycomb structural frame, and the hydrophobic micro-cone array is disposed on the surface of the biomimetic fin and located inside the honeycomb structural frame; forming a hydrophobic micro-cone array-honeycomb composite structure. Preferably, after several micro-units are combined, a hydrophobic layer is formed on the surface of the biomimetic fin; when droplets condense on the fin surface, they slide off in time, avoiding ice formation and reducing the thermal resistance caused by liquid film accumulation.

[0005] Preferably, the adjacent bionic fins are fixed by welding or integrally bent into shape by an external frame.

[0006] A second aspect of the present invention provides a finned tube heat exchanger based on a biomimetic lotus leaf-honeycomb structure, wherein several biomimetic fins are connected end to end, and a refrigerant working fluid pipeline unit passes through the biomimetic fins. The biomimetic fins connected end to end are formed by integrally bending a metal plate; The refrigerant piping unit includes several parallel pipes, with adjacent pipes spaced at equal intervals; the bionic fins have holes in the middle, and the diameter of the holes is the same as the diameter of the pipe wall; each pipe runs through all the bionic fins and forms inlets and outlets at both ends of the bionic fins. The surface of the biomimetic fins is divided into multiple micro-units; the micro-units are connected to the pipe wall and serve as extensions of the pipe wall, increasing the contact area between the refrigerant and the outside environment for heat exchange.

[0007] Preferably, the pipes are fixed to the finned radiator by welding.

[0008] Preferably, the hydrophobic microcone array is derived by shaping and modifying the fin surface.

[0009] Preferably, in the hydrophobic microcone array-honeycomb composite structure, the honeycomb structure frame has a side length of 20mm, a width of 2mm, and a height of 4mm; the microcones have a diameter of 2mm and a height of 3mm, and the surface of the microcones is distributed with CuO nanoflower or nanograss nanoscale rough structures, with a microcone spacing of 1mm.

[0010] The height difference between the honeycomb structure frame and the microcone array is 1 mm, and the spacing between the microcones is 1 mm. The surface of the composite structure is modified with a low surface energy coating to form a superhydrophobic surface with a contact angle ≥150° and a roll-off angle ≤10°.

[0011] Preferably, the pipe wall is made of copper, and the inlet and outlet diameters of the pipe are 50 mm.

[0012] Preferably, the frame of the bionic fin and the connecting parts of the connected bionic fins are provided with a chrome-plated protective layer. The thickness of the protective layer is 0.07 mm.

[0013] The synergistic mechanism between the honeycomb structure and the hydrophobic microcone array is as follows: the honeycomb frame divides the microcone array into independent units, and the direct impact of external loads on the microcones is reduced through structural mechanics design; the hydrophobic microcone array achieves rapid droplet rolling and self-cleaning through a multi-level rough structure, while increasing the heat transfer surface area and enhancing the convective heat transfer effect.

[0014] A third aspect of the present invention provides a method for preparing a finned tube heat exchanger based on a biomimetic lotus leaf-honeycomb structure, the method comprising the following specific steps: S1. Substrate pretreatment: Select copper fins, ultrasonically clean with acetone for 10 minutes to remove surface oil, and dry for later use. S2. Laser layered micromachining: A hexagonal honeycomb structure with a side length of 20mm, a wall width of 2mm, and a depth of 4mm is etched at a designated position on the fin surface using a 355nm ultraviolet laser in a single process. Secondary processing involves fabricating a microcone array with a diameter of 2mm and a height of 3mm within the honeycomb cell at a 1mm spacing, with a 1mm platform retained at the top of the microcones; S3. Surface roughening treatment: The processed fins are immersed in a 0.1 mol / L NaOH solution and treated at a constant temperature of 60℃ for 30 min to generate a CuO nanoflower and nanograss composite rough structure. S4. Low surface energy modification: 1H,1H,2H,2H-perfluorodecyltrimethoxysilane PFTS is coated on the fin surface by vapor deposition and cured at 80℃ for 2h to form a superhydrophobic coating. S5, Bending and shaping: The processed substrate is bent and shaped to form multiple fin structures connected end to end; S6. Pipe welding: Weld the pipes to the pre-reserved openings in the finned structure to form a tubular heat exchanger.

[0015] Compared with the prior art, the present invention has the following beneficial technical effects: The superhydrophobic surface of this invention allows for a water droplet contact angle ≥150° and a roll-off angle ≤10°, and dust particles are removed as the droplets roll off, preventing dust accumulation from affecting heat transfer.

[0016] (2) The microcone array of the present invention increases the heat transfer area of ​​the fin surface by 15%-20%, and the honeycomb structure regulates the flow field and promotes thermal boundary. Layer disturbance. Experimental data shows that, under the same operating conditions (supercooling ΔT = 10K), the superhydrophobic honeycomb-lotus leaf composite of this invention... The heat transfer coefficient of the composite structure reaches 60 kW·m²·K⁻¹, which is an improvement compared to the surface heat transfer coefficient of ordinary fins (30 kW·m⁻²·K⁻¹). 100%, a 33.3% improvement compared to superhydrophobic surfaces with only a honeycomb structure (45 kW·m²·K⁻¹), significantly enhancing... This improved heat exchange efficiency. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of the heat exchanger in an embodiment of the present invention; Figure 2 This is a three-dimensional structural diagram of the biomimetic fins in an embodiment of the present invention; Figure 3 This is a top view of the biomimetic fins in an embodiment of the present invention; Figure 4 This is a side view of the heat exchanger in an embodiment of the present invention; Figure 5 This is a schematic diagram of the refrigerant flow pipeline in an embodiment of the present invention; Figure 6 This is a flowchart of the preparation method in an embodiment of the present invention; Figure 7 This is a table showing the surface undercooling and heat transfer coefficient of different samples in the embodiments of the present invention.

[0018] Reference numerals: 1. Bionic fin; 2. Hydrophobic microcone array; 3. Honeycomb structure frame; 4. Refrigerant working fluid piping unit; 41. Pipe; 5. Pipe wall. Detailed Implementation Example

[0019] like Figure 2-3 As shown, this embodiment provides a biomimetic fin based on a biomimetic lotus leaf-honeycomb structure, including an outer frame and a heat exchange unit. The outer frame is used to connect with other biomimetic fins 1. The heat exchange unit is located on the surface of the biomimetic fin 1; The surface of the biomimetic fin 1 is divided into multiple micro-units; The micro-unit includes a honeycomb structure frame 3 and a hydrophobic micro-cone array 2; adjacent micro-units abut against each other through the honeycomb structure frame 3, and the hydrophobic micro-cone array 2 is disposed on the surface of the biomimetic fin 1 and located inside the honeycomb structure frame 3; forming a hydrophobic micro-cone array-honeycomb composite structure. like Figure 2 As shown, the biomimetic fin 1 measures 5000mm × 150mm × 3000mm, with an integrated bending spacing of 8mm and a single fin thickness of 2mm. It employs a special surface structure composed of multiple etched honeycomb units, forming a dense hydrophobic micro-cone array surface with strong heat transfer and self-cleaning capabilities. The outer perimeter is chrome-plated at 0.7mm, and the outer edge is 5mm high, creating a 1mm height difference with the inner honeycomb frame to protect the structure from damage.

[0020] In this embodiment, several micro-units are combined to form a hydrophobic layer on the surface of the biomimetic fin 1; this allows droplets to slide off promptly when they condense on the fin surface, preventing ice formation and reducing thermal resistance caused by liquid film accumulation. Adjacent biomimetic fins 1 are fixed by welding with an external frame or integrally bent into shape. Figure 3 As shown, the enclosure structure of honeycomb structure 3 adopts a hexagonal structure characteristic similar to a honeycomb, which can be achieved through laser etching. The honeycomb frame is 4mm high, 2mm wide, and 20mm long on each side. Example

[0021] like Figure 1 As shown, this embodiment provides a finned tube heat exchanger based on a biomimetic lotus leaf-honeycomb structure, including the biomimetic fins in Embodiment 1; wherein, several biomimetic fins 1 are connected end to end, and the refrigerant working fluid pipe unit 4 passes through the biomimetic fins 1, and the heat exchanger has a total of 30 finned structures of the same type; as Figure 1 As shown, the spatial distribution of the radiator fluid pipe 1 with a diameter of 50mm, the hydrophobic microcone array 2 with a diameter of 2mm, a height of 3mm, a spacing of 1mm, and the honeycomb support structure 3 with a side length of 20mm.

[0022] like Figure 4 As shown, the biomimetic fins 1 connected end to end are formed by integrally bending a metal plate; The refrigerant piping unit 4 includes several parallel pipes 41, with adjacent pipes 41 arranged at equal intervals; the bionic fin 1 has a hole in the middle, and the diameter of the hole is the same as the diameter of the pipe wall 5; each pipe 41 passes through all the bionic fins 1, and forms inlets and outlets at the beginning and end of the bionic fins 1. The surface of the biomimetic fin 1 is divided into multiple micro-units; the micro-units are connected to the pipe wall 5 of the pipe 41 and serve as an extension of the pipe wall 41, thereby increasing the contact area between the refrigerant and the outside environment for heat exchange.

[0023] In this embodiment, pipe 41 is fixed to the finned radiator by welding. The refrigerant flow pipe is made of copper, which is corrosion-resistant and has good thermal conductivity.

[0024] In this embodiment, the hydrophobic microcone array 2 is formed and modified on the surface of the fin. In the hydrophobic microcone array-honeycomb composite structure, the honeycomb structure frame 3 has a side length of 20mm, a width of 2mm, and a height of 4mm; the microcones have a diameter of 2mm and a height of 3mm, and the surface of the microcones has a nanoscale rough structure. The height difference between the honeycomb structure frame 3 and the microcone array is 1 mm, and the microcone spacing is 1 mm; the surface of the composite structure is coated with a low surface energy coating, maintaining a contact angle ≥150° and a roll-off angle ≤10°. In this embodiment, as Figure 5 As shown, the pipe wall 5 is a copper pipe, and the inlet and outlet diameters of the pipe 41 are 50 mm.

[0025] In this embodiment, a chrome-plated protective layer is provided on the frame of the bionic fin 1 and the connecting part of the connected bionic fin 1; the thickness of the protective layer is 0.07mm.

[0026] To verify the heat transfer enhancement effect of the biomimetic lotus leaf-honeycomb structure fins described in this embodiment, the following comparative experiment was conducted: 1. Sample preparation Four fin samples with different surface structures were prepared, all using copper fins (100mm x 100mm x 2mm) as the substrate: Sample A (ordinary surface): only cleaned with acetone, without surface microstructure treatment.

[0027] Sample B (superhydrophobic surface): processed according to steps S3-S4 of the present invention, only a nano-rough structure is generated and modified with a low surface energy coating, without microcone array and honeycomb structure.

[0028] Sample C (superhydrophobic honeycomb surface): A hexagonal honeycomb structure (side length 20mm, wall width 2mm, depth 4mm) was etched once according to step S2 of the present invention, and then processed by S3-S4, but without microcone array.

[0029] Sample D (superhydrophobic honeycomb-lotus leaf surface of the present invention): prepared according to the complete steps of Example 3 of the present invention, having a honeycomb structural framework and a hydrophobic microcone array composite structure.

[0030] 2. Testing apparatus A heat transfer performance testing platform was adopted, including: a constant temperature circulating water bath (to control the temperature of the cold source) and thermocouples (accuracy +0.1°C). Heat flow meter and data acquisition system. The sample is vertically mounted in the test section, with the wall temperature controlled on one side by a semiconductor cooling chip, and the other side... One side is exposed to ambient air. The subcooling degree ΔT (the ratio of wall temperature to air dew point temperature) is changed by adjusting the cooling power. (Difference), record the heat flux density q at steady state, and calculate the heat transfer coefficient h = q / ΔT.

[0031] Test conditions Ambient temperature: 25℃±1°C Relative humidity: 60%±5% Supercooling AT settings: 0K, 2.5K, 5K, 7.5K, 10K, 12.5K, 15K, 17.5K, 20K, 22.5K Each working condition was tested three times, and the average value was taken.

[0032] 4. Test Results The heat transfer coefficient h (unit: kW·m²²·K⁻¹) of each sample under different degrees of subcooling is shown in Table 1.

[0033] Table 1. Comparison of heat transfer coefficients of fins with different surface structures From the raw data, a typical working condition (such as ΔT=10K) was selected for calculation, and the calculation results are shown in Table 2: Table 2 Calculated values ​​for typical operating conditions (e.g., ΔT=10K) Calculate the improvement rate: Superhydrophobic honeycomb - lotus leaf surface vs. ordinary surface: 60 / 30 ≈ 100% improvement Superhydrophobic honeycomb surface - lotus leaf surface vs. superhydrophobic honeycomb surface: 60 / 45 ≈ 33.3% improvement Superhydrophobic honeycomb surface vs. ordinary surface: 45 / 30 ≈ 50% improvement (3) The mechanical support of the honeycomb frame enables the composite structure to withstand more than 200 cycles of linear wear from 1000-grit sandpaper, with a hydrophobic performance attenuation rate of ≤5%.

[0034] To verify the mechanical protection effect of the honeycomb frame described in this invention on the hydrophobic microcone array, a linear wear comparison experiment was conducted.

[0035] 1. Sample preparation Two copper fin samples with different surface structures were prepared (substrate size: 50 mm × 50 mm × 2 mm): Sample E (composite structure of the present invention): prepared according to the complete steps of Example 3 of the present invention, having a honeycomb structure frame (side length 20 mm, wall width 2 mm, height 4 mm) and an internal hydrophobic microcone array (diameter 2 mm, height 3 mm, spacing 1 mm), and the surface is chemically oxidized to generate CuO nano-rough structure and modified with a low surface energy coating.

[0036] Sample F (comparative structure): A hydrophobic microcone array (diameter 2 mm, height 3 mm, spacing 1 mm) was prepared on the fin surface by secondary processing according to step S2 of the present invention, without a honeycomb structure frame, and subsequently subjected to the same chemical oxidation and low surface energy modification treatment.

[0037] 2. Testing equipment A linear abrasion tester (such as Taber® Linear Abraser) is used, equipped with 1000-grit silicon carbide sandpaper as the abrasive medium. The abrasive head is cylindrical (10 mm in diameter), and a constant load is applied.

[0038] 3. Test Conditions Load: 200 g Wear stroke: 25 mm Wear frequency: 60 times / minute Ambient temperature: 25℃ ± 2℃ Relative humidity: 40% ± 5% 4. Testing Procedures (1) Before the test, the initial static water contact angle (CA) of each sample was measured using a contact angle measuring instrument (accuracy ±1°). Five different positions were measured for each sample, and the average value was taken.

[0039] (2) Fix the sample on the platform of the wear tester and make the grinding head move linearly and reciprocally on the surface of the sample. After every 50 wear cycles, pause the test, blow away the surface debris with compressed air, measure the contact angle again, and record the contact angle value at the current wear cycle.

[0040] (3) Repeat step (2) until the wear count reaches 250 times or the contact angle decreases significantly (below 150°).

[0041] (4) Calculate the hydrophobic performance degradation rate: degradation rate = (initial CA - CA after wear) / initial CA × 100%.

[0042] (5) Three parallel samples were tested for each type of sample, and the average value of the results was taken.

[0043] 5. Test Results The test results are shown in Table 3. Table 3. Changes in contact angle before and after wear of specimens with different structures Number of wears Sample E (composite structure of the present invention) Sample F (comparative structure, no honeycomb structure) 0 162° 163° 50 161° 158° 100 161° 152° 150 160° 145° 200 159° 138° 250 158° 130° As shown in Table 3, after 200 linear wear cycles, the contact angle of sample E of this invention decreased from 162° to 159°, with an attenuation rate of only 1.85%, still maintaining a superhydrophobic state (>150°); while the contact angle of the control sample F decreased from 163° to 138°, with an attenuation rate as high as 15.3%, and it lost its superhydrophobic properties. This indicates that the honeycomb frame effectively protects the microcone array, enabling the composite structure to withstand at least 200 wear cycles with a hydrophobic performance attenuation rate ≤5%.

[0044] (4) In complex environments such as high humidity and dust, the radiator can maintain efficient heat dissipation for a long time without frequent maintenance. It has a self-cleaning function. Example

[0045] like Figure 6 As shown, the fabrication process of the honeycomb unit composite structure in the biomimetic fins is as follows: initial laser processing to form a honeycomb frame, secondary processing to prepare a microcone array within the honeycomb, chemical oxidation to generate a nano-rough structure, and low surface energy modification (PFTS coating). This embodiment provides a method for fabricating a finned tube heat exchanger based on a biomimetic lotus leaf-honeycomb structure, and the fabrication of the heat exchanger as described in Example 2 includes the following specific steps: S1. Substrate pretreatment: Select copper fins, ultrasonically clean with acetone for 10 minutes to remove surface oil, and dry for later use. S2. Laser layered micromachining: A hexagonal honeycomb structure with a side length of 20mm, a wall width of 2mm, and a depth of 4mm is etched at a designated position on the fin surface using a 355nm ultraviolet laser in a single process. Secondary processing involves fabricating a microcone array with a diameter of 2mm and a height of 3mm within the honeycomb cell at a 1mm spacing, with a 1mm platform retained at the top of the microcones; S3. Surface roughening treatment: The processed fins are immersed in a 0.1 mol / L NaOH solution and treated at a constant temperature of 60℃ for 30 min to generate a CuO nanoflower and nanograss composite rough structure. S4. Low surface energy modification: 1H,1H,2H,2H-perfluorodecyltrimethoxysilane PFTS is coated on the fin surface by vapor deposition and cured at 80℃ for 2h to form a superhydrophobic coating. S5, Bending and shaping: The processed substrate is bent and shaped to form multiple fin structures connected end to end; S6. Pipe welding: Weld the pipes to the pre-reserved openings in the finned structure to form a tubular heat exchanger.

[0046] In this embodiment, the biomimetic fins, based on the honeycomb unit hydrophobic microcone array structure 2, reduce the condensate film thickness and enhance heat transfer, thereby achieving self-cleaning through hydrophobic properties. Simultaneously, the hexagonal honeycomb structure 3 enhances structural strength and extends service life. The pipe wall 5 is welded to the pre-drilled holes in the biomimetic fins, amplifying the refrigerant effect. Refrigerant flows through the pipe inlet and outlet 4. The refrigerant, through heat exchange between the pipe wall 5 and the biomimetic fins 1, achieves efficient control of the external temperature.

[0047] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited thereto. Various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention.

Claims

1. A fin based on a biomimetic lotus leaf-honeycomb structure, comprising an outer frame and a heat exchange unit, characterized in that, The outer frame is used to connect with other biomimetic fins (1); The heat exchange unit is located on the surface of the biomimetic fin (1); The surface of the biomimetic fin (1) is divided into multiple micro-units; The micro-unit includes a honeycomb structure frame (3) and a hydrophobic micro-cone array (2); adjacent micro-units abut against each other through the honeycomb structure frame (3), and the hydrophobic micro-cone array (2) is disposed on the surface of the biomimetic fin (1) and located inside the honeycomb structure frame (3); forming a hydrophobic micro-cone array-honeycomb composite structure.

2. The fin based on a biomimetic lotus leaf-honeycomb structure according to claim 1, characterized in that, After several micro-units are combined, a hydrophobic layer is formed on the surface of the biomimetic fin (1); when the droplets condense on the fin surface, they slide off in time, avoiding ice formation and reducing the thermal resistance caused by liquid film accumulation.

3. The fin based on a biomimetic lotus leaf-honeycomb structure according to claim 1, characterized in that, The adjacent bionic fins (1) are fixed by welding or integrally bent by the external frame.

4. A finned tube heat exchanger based on a biomimetic lotus leaf-honeycomb structure, comprising the biomimetic fins as described in any one of claims 1-3, characterized in that, Several biomimetic fins (1) are connected end to end, and the refrigerant working fluid pipeline unit (4) runs through the biomimetic fins (1). The biomimetic fins (1) connected end to end are formed by integrally bending a metal plate; The refrigerant working fluid piping unit (4) includes several parallel pipes (41), and adjacent pipes (41) are equally spaced; the middle of the bionic fin (1) has a hole, and the diameter of the hole is the same as the diameter of the pipe wall (5); each pipe (41) runs through all the bionic fins (1), and forms inlet and outlet at the beginning and end of the bionic fins (1); The surface of the biomimetic fin (1) is divided into multiple micro-units; the micro-units are connected to the pipe wall (5) of the pipe (41) and serve as an extension of the pipe wall (41), increasing the contact area between the refrigerant and the outside world.

5. A finned tube heat exchanger based on a biomimetic lotus leaf-honeycomb structure according to claim 4, characterized in that, The pipe (41) is fixed to the finned radiator by welding.

6. A finned tube heat exchanger based on a biomimetic lotus leaf-honeycomb structure according to claim 4, characterized in that, The hydrophobic microcone array (2) is derived from shaping and modifying the fin surface.

7. A finned tube heat exchanger based on a biomimetic lotus leaf-honeycomb structure according to claim 4, characterized in that, In the hydrophobic microcone array-honeycomb composite structure, the honeycomb structure frame (3) has a side length of 20mm, a width of 2mm, and a height of 4mm; the microcones have a diameter of 2mm and a height of 3mm, and the surface of the microcones has a nanoscale rough structure. The height difference between the honeycomb structure frame (3) and the microcone array is 1 mm, and the microcone spacing is 1 mm; the surface of the composite structure is modified with a low surface energy coating to form a superhydrophobic surface with a contact angle ≥150° and a roll-off angle ≤10°.

8. A finned tube heat exchanger based on a biomimetic lotus leaf-honeycomb structure according to claim 4, characterized in that, The pipe wall (5) is a copper pipe, and the inlet and outlet diameter of the pipe (41) is 50 mm.

9. A finned tube heat exchanger based on a biomimetic lotus leaf-honeycomb structure according to claim 4, characterized in that, The frame of the bionic fin (1) and the connection part of the connected bionic fin (1) are all provided with a chrome-plated protective layer. The thickness of the protective layer is 0.07 mm.

10. A method for fabricating a finned tube heat exchanger based on a biomimetic lotus leaf-honeycomb structure, wherein the heat exchanger is fabricated as described in any one of claims 4-9, characterized in that, The specific steps include the following: S1. Substrate pretreatment: Select copper fins, ultrasonically clean with acetone for 10 minutes to remove surface oil, and dry for later use. S2. Laser layered micromachining: A hexagonal honeycomb structure with a side length of 20mm, a wall width of 2mm, and a depth of 4mm is etched at a designated position on the fin surface using a 355nm ultraviolet laser in a single process. Secondary processing involves fabricating a microcone array with a diameter of 2mm and a height of 3mm within the honeycomb cell at a 1mm spacing, with a 1mm platform retained at the top of the microcones; S3. Surface roughening treatment: The processed fins are immersed in a 0.1 mol / L NaOH solution and treated at a constant temperature of 60℃ for 30 min to generate a CuO nanoflower and nanograss composite rough structure. S4. Low surface energy modification: 1H,1H,2H,2H-perfluorodecyltrimethoxysilane PFTS is coated on the fin surface by vapor deposition and cured at 80℃ for 2h to form a superhydrophobic coating. S5, Bending and shaping: The processed substrate is bent and shaped to form multiple fin structures connected end to end; S6. Pipe welding: Weld the pipes to the pre-reserved openings in the finned structure to form a tubular heat exchanger.

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