Oil smoke purification device and preparation method thereof

Abstract

The invention discloses an oil fume purification device and a preparation method thereof. The device comprises an air inlet cover, a flow guide plate, an air duct, a bionic gradient adsorption interface, a low-voltage pulsed electric field generation device, an oil collection tank and a temperature control module. The bionic gradient adsorption interface is of a multi-stage gradient micro-nano composite structure, is composed of a bottom-layer micron-scale columnar array and an upper-layer nano-scale oleophobic coating, and is in gradient distribution in the oil smoke airflow direction; the electric field intensity of the low-voltage pulse electric field generating device is gradually reduced in a gradient mode in the oil fume airflow direction and is cooperatively matched with the bionic gradient adsorption interface, and efficient oil fume trapping, self-cleaning, maintenance-free and secondary pollution-free are achieved.

Description

Technical Field

[0001] This invention relates to the field of kitchen appliance technology, and more particularly to a biomimetic composite adsorption type oil fume purification device for range hoods and its preparation method. Background Technology

[0002] Range hoods are indispensable ventilation and purification devices in modern family kitchens. Their core function is to efficiently capture the particulate matter from cooking fumes, ensuring indoor air quality and human health. With the improvement of living standards and increased environmental awareness, higher demands are being placed on the purification efficiency, ease of use, and safety of range hoods.

[0003] Existing oil fume purification methods can be mainly divided into the following three categories: The first type is mechanical filtration, which uses multi-layer metal or non-woven fabric filters to intercept oil fume particles. This technology is simple in structure and low in cost, but its drawbacks are: the filter is easily clogged by oil droplets, and with prolonged use, the air resistance increases sharply, the fan efficiency decreases, the noise increases, and frequent disassembly and cleaning or filter replacement is required. The cleaning process is cumbersome for users, and the oil in the cleaning solution can easily cause secondary pollution.

[0004] The second type is electrostatic precipitator, which uses a high-voltage electrostatic field to charge oil fume particles and then adsorb them onto the collecting electrode. This technology has a high collection efficiency for submicron particles, but it has obvious drawbacks: the high-voltage electric field usually requires a voltage of more than 5kV, which is prone to corona discharge and generates secondary pollutants such as ozone, which irritate the human respiratory tract; the insulation performance of the electrode surface deteriorates after long-term oil accumulation, which can easily cause sparking or even fire hazards; in addition, electrostatic precipitators have a complex structure and large size, making them difficult to integrate into household range hoods.

[0005] The third type is adsorption, which uses porous materials such as activated carbon to adsorb organic matter in cooking fumes. The drawbacks of this technology are: limited adsorption capacity, requiring frequent replacement after saturation, and the adsorption materials are mostly disposable consumables, resulting in high operating costs and significant resource waste, making it unsuitable as a mainstream method for purifying cooking fumes. Summary of the Invention

[0006] To address the aforementioned technical challenges, this invention provides an oil fume purification device and its preparation method. By constructing a synergistic system of a biomimetic gradient micro-nano adsorption interface and a low-voltage pulsed electric field, the invention solves the technical problems of low collection efficiency, easy clogging, difficulty in cleaning, and secondary pollution in existing oil fume purification devices.

[0007] The present invention provides an oil fume purification device, comprising: An air inlet hood, located at the air inlet of the range hood, is used to guide the airflow of cooking fumes into the device. It is shaped like a horn or a rectangular grille and is made of metal or high-temperature resistant plastic.

[0008] The deflector, connected to the air inlet hood, is used to change the direction of the oil fume airflow and extend the airflow path, allowing oil fume particles sufficient time to contact and be captured by the biomimetic adsorption interface. The deflector can be configured as a single-layer or multi-layer staggered structure to increase the contact area between the airflow and the interface.

[0009] The air duct, located between the guide plate and the fan, forms a channel for the flow of oil fumes. Its inner wall surface is provided with a biomimetic adsorption interface, which serves as the final barrier for capturing oil fume particles.

[0010] A biomimetic gradient adsorption interface is disposed on at least a portion of the surface of the air inlet hood, the guide plate, and the inner wall of the air duct, for actively capturing oil fume particles and achieving self-cleaning and sliding of oil droplets.

[0011] The low-voltage pulsed electric field generator includes flexible electrodes arranged on both sides of the biomimetic gradient adsorption interface, and a pulsed power supply module electrically connected to the flexible electrodes, which is used to induce the coalescence of oil fume particles to increase the particle size and improve the capture efficiency.

[0012] The oil collection trough, located at the bottom of the air inlet hood, is used to collect oil droplets that slide down from the biomimetic gradient adsorption interface. Its shape is a long strip or a circular groove, and its volume is adapted according to the range hood model.

[0013] The temperature control module, located inside the oil collection tank, is used to regulate the temperature of the oil collection tank, prevent oil droplets from solidifying, and ensure smooth flow.

[0014] The biomimetic gradient adsorption interface is a multi-level gradient micro-nano composite structure, with a bottom layer consisting of a micron-scale columnar array and an upper layer consisting of a nano-scale oleophobic coating, exhibiting a spatial gradient change in the direction of the oil fume airflow.

[0015] The columnar array is formed on the substrate surface using plasma etching, and its structural parameters are gradient-distributed in the direction of oil fume airflow, as detailed below: area Column height (μm) Column spacing (μm) Column cross-sectional shape Functional positioning Air intake area 10–20 15–20 Circular or hexagonal High-efficiency capture Deflector area 20–35 10–15 Circular or hexagonal Fully coagulated Inner wall area of ​​the air duct 35–50 5–10 Circular or hexagonal Rapidly sliding The columnar array has a column height to column diameter ratio of ≥1:1, and the column sidewalls have a taper of 5–15°. This taper design can reduce the contact area between the oil droplets and the column sidewalls, reduce adhesion, and promote the oil droplets to slide off.

[0016] In addition, the nanoscale oleophobic coating is applied to the surface of the micron-scale columnar array. It is a composite coating of fluorinated silane oleophobic material and nano-inorganic particles. The fluorinated silane is selected from at least one of perfluorodecyltrimethoxysilane, perfluorooctyltriethoxysilane, and perfluorodecyltrichlorosilane. The nano-inorganic particles are selected from at least one of nano-SiO2, nano-TiO2, and nano-Al2O3, with a particle size of 20–100 nm. The mass ratio of fluorinated silane to nano-inorganic particles is 10:1 to 5:1.

[0017] The thickness of the nanoscale oleophobic coating is 50–200 nm, the surface roughness Ra≤50 nm, and after coating treatment, the surface contact angle of the biomimetic gradient adsorption interface is ≥150° and the roll-off angle is ≤5°.

[0018] The introduction of nano-inorganic particles has a dual effect: first, it increases the surface roughness of the coating and improves the oleophobic properties; second, it constructs secondary nanostructures and multi-level composite structures on the surface of micron-pillars formed by plasma etching, further enhancing the superoleophobic properties.

[0019] The electric field strength and pulse frequency of the low-voltage pulsed electric field generator are configured such that the median particle size D after the condensation of 0.1–1 μm oil fume aerosol is... 50 The size should be controlled within the range of 10–30 μm.

[0020] The flexible electrodes of the low-voltage pulsed electric field generator are made of conductive fiber cloth or conductive flexible film, with a thickness of 0.1–1 mm and a surface resistivity ≤10 Ω / sq. They are attached to both sides of the biomimetic gradient adsorption interface, with an electrode spacing of 2–10 mm. The advantage of flexible electrodes is that they can be attached to curved or irregular surfaces, adapting to the complex internal structure of range hoods. The pulse power module outputs a pulse voltage ≤12V, a pulse frequency of 10–100Hz, a duty cycle of 10%–50%, and an output electric field strength of 0.5–2kV / cm. The low-voltage design avoids ozone generation and eliminates the risk of electric shock.

[0021] The low-voltage pulse electric field generator has a gradually decreasing electric field strength along the direction of the oil fume airflow, wherein: the electric field strength in the air inlet hood area is 1.5–2 kV / cm; the electric field strength in the guide plate area is 1.0–1.5 kV / cm; and the electric field strength in the inner wall area of ​​the air duct is 0.5–1.0 kV / cm.

[0022] This gradient configuration matches the functional zoning of the biomimetic gradient adsorption interface: the high electric field intensity in the air inlet hood area promotes rapid particle polarization and initial agglomeration; the electric field intensity in the guide plate area maintains the agglomeration process; and the low electric field intensity in the inner wall area of ​​the air duct prevents the already agglomerated oil droplets from breaking up again, while reducing energy consumption.

[0023] The biomimetic gradient adsorption interface is tilted at an angle of 5–30°, with the tilt direction facing the oil collection tank. The tilted design utilizes gravity to promote the sliding of oil droplets; if the tilt angle is too small, the sliding speed is slow, and if the tilt angle is too large, it occupies space.

[0024] The temperature control module installed in the oil collection tank maintains the heating temperature between 35 and 45°C. This temperature range is coupled with the surface energy characteristics of the fluorinated silane oleophobic coating, and the specific mechanism is as follows: When the temperature is below 35℃, the viscosity of the oil droplets increases, the roll-off angle increases to ≥8°, the slippage is delayed, and residues are easily formed at the interface edge. When the temperature is above 45℃, the molecular chain movement of the fluorosilane coating intensifies, the surface energy increases to ≥15mN / m, the oleophobicity decreases, and the contact angle decreases to ≤140°. When the temperature is controlled between 35–45℃, the surface energy of the coating is stable at ≤10mN / m, the roll-off angle is ≤3°, and zero-residue slippage of the oil droplets under gravity is achieved. The synergistic effect of this temperature control module and the biomimetic gradient adsorption interface enables the device to maintain good self-cleaning performance even in low-temperature environments in winter.

[0025] The present invention also provides a method for preparing the oil fume purification device, comprising the following steps: Step 1: Substrate Pretreatment The metal or plastic substrates of the air inlet shroud, guide vanes, and inner walls of the air duct are ultrasonically cleaned using anhydrous ethanol or acetone for 10–30 minutes to remove surface oil and impurities. They are then dried at 60–80°C for 30–60 minutes. After drying, plasma pretreatment is performed using oxygen or argon gas at a power of 100–200W for 5–10 minutes to raise the surface activation energy of the substrate to ≥72 mN / m. The purpose of plasma pretreatment is to introduce active groups such as hydroxyl and carboxyl groups, enhancing the adhesion between the subsequent coating and the substrate.

[0026] Step 2: Gradient Plasma Etching A reactive ion etching (RIE) system was employed, using an SF6 / O2 mixed gas as the etching gas. The SF6 to O2 flow ratio was 1:2 to 1:4, the etching power was 100–300 W, and the gas pressure was 5–20 Pa. SF6 provided fluorine radicals as the etching gas, while O2 promoted the oxidation reaction and regulated the etching rate. The etching area and etching time were controlled by a mask, forming a gradient-distributed micron-sized columnar array on the substrate surface along the direction of the oil fume flow. The etching depth was 10–20 μm in the air inlet area, the column spacing was 15–20 μm, and the etching time was 5–10 min; the etching depth was 20–35 μm in the guide plate area, the column spacing was 10–15 μm, and the etching time was 10–20 min; and the etching depth was 35–50 μm in the inner wall area of ​​the air duct, the column spacing was 5–10 μm, and the etching time was 20–30 min. During these etching processes, the sidewalls of the column naturally form a taper of 5–15°, due to the difference in etching rate between the top and bottom of the column.

[0027] Step 3: Applying the nanocomposite coating Fluorosilane oleophobic materials are mixed with nano-inorganic particles at a mass ratio of 10:1 to 5:1 and dispersed in anhydrous ethanol or isopropanol to form a spraying solution with a solid content of 1%–5%. The nanoparticles are uniformly dispersed using ultrasonic dispersion or high-speed stirring. The solution is applied to the etched surface by spraying or dipping at a rate of 5–20 g / m². It is then thermotreated at 80–120°C for 30–60 min to form a nanocomposite coating with a thickness of 50–200 nm and a surface roughness Ra ≤ 50 nm. After curing, the surface properties are tested using a contact angle meter; the static contact angle is ≥150°, and the roll-off angle is ≤5° using the tilt plate method.

[0028] Step 4: Electrode placement and electric field Conductive fiber cloth or conductive flexible film is cut into a shape that matches the biomimetic gradient adsorption interface region and attached to both sides of the interface at a spacing of 3–8 mm, and then connected to a pulse power module. The output parameters of the pulse power module are configured such that: the electric field strength in the air inlet area is 1.5–2 kV / cm; the electric field strength in the guide plate area is 1.0–1.5 kV / cm; and the electric field strength in the inner wall area of ​​the air duct is 0.5–1.0 kV / cm. The pulse frequency is 20–80 Hz, and the duty cycle is 20%–40%.

[0029] Step 5: Assemble the oil collection tank and temperature control module Install the oil collection tank at the bottom of the device. Inside the tank, install a PID temperature control module and heating elements such as a PTC heating element or resistance wire. Configure a PT100 or K-type thermocouple temperature sensor and set the control temperature to 38–42℃. After completing the assembly, conduct a sealing test with an airtightness of ≥99% and an electric field insulation test with an insulation resistance of ≥100MΩ to ensure the device's safety and reliability.

[0030] Compared with existing technologies, this invention, through the synergistic effect of a biomimetic gradient adsorption interface and a low-voltage pulsed electric field, allows large-diameter oil droplets to completely slide into the oil collection tank under gravity, leaving no residue and preventing blockage. The low-voltage pulsed electric field is far below the human safety voltage threshold, eliminating the risk of electric shock. With the electric field strength controlled below 2kV / cm, no corona discharge occurs, thus preventing ozone generation. The integrated design of the electrode and biomimetic interface prevents oil droplets from contacting the electrodes during sliding, eliminating electric field failure caused by oil accumulation. The entire machine operates without releasing any chemical substances, meeting green environmental protection requirements. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the overall structure of the oil fume purification device of the present invention; Figure 2 This is a partial cross-sectional view of the biomimetic gradient adsorption interface of the present invention. Figure 3This is a schematic diagram of the planar structure of the micrometer-scale columnar array of the present invention; Figure 4 This is a schematic diagram of the electrode layout of the low-voltage pulse electric field generator of the present invention. Detailed Implementation

[0032] The present invention will be further described in detail below with reference to the embodiments. The embodiments are only intended to provide a clearer understanding of the technical features, objectives and effects of the present invention.

[0033] This application discloses an oil fume purification device, characterized in that it includes: an air inlet hood 1, a guide plate 2, and an inner wall of an air duct 3; a biomimetic gradient adsorption interface 4 disposed on at least part of the surfaces of the air inlet hood 1, the guide plate 2, and the inner wall of the air duct 3; a low-voltage pulse electric field generating device disposed on both sides of the biomimetic gradient adsorption interface 4; and an oil collection tank 7 disposed at the bottom of the low-voltage pulse electric field generating device; the biomimetic gradient adsorption interface 4 is a multi-level gradient micro-nano composite structure, including a bottom layer of micron-level columnar array 41 and an upper layer of nano-level oleophobic coating.

[0034] The micron-sized columnar array 41 is gradient-distributed along the direction of the oil fume airflow. The column height in the air inlet hood 1 region is less than that in the guide plate 2 region, and the column height in the guide plate 2 region is less than that in the inner wall 3 region of the air duct. The electric field intensity of the low-pressure pulse electric field generator decreases gradient along the direction of the oil fume airflow. The electric field intensity in the air inlet hood 1 region is greater than that in the guide plate 2 region, and the electric field intensity in the guide plate 2 region is greater than that in the inner wall 3 region of the air duct.

[0035] Among them, the column height of the micron-scale columnar array 41 is 10–50 μm, the column spacing is 5–20 μm, and the aspect ratio is ≥1:1; the micron-scale oleophobic coating is a composite coating of fluorinated silane materials and nano-inorganic particles, with a thickness of 50–200 nm and a surface roughness Ra≤50 nm.

[0036] The low-voltage pulsed electric field generator includes a flexible electrode 5 and a pulsed power supply module 6. The flexible electrode 5 is a conductive fiber cloth or a conductive flexible film, with an electrode spacing of 2–10 mm, a pulse voltage of ≤12V, a pulse frequency of 10–100Hz, and an electric field strength of 0.5–2kV / cm.

[0037] Among them, the biomimetic gradient adsorption interface 4 is set at an angle of 5–30°, and the tilting direction is towards the oil collection tank 7; the oil collection tank 7 is equipped with a PID temperature control module 8 and a PTC heating element or resistance wire heating element 9, and is equipped with a PT100 or K-type thermocouple temperature sensor 10, with a heating temperature of 35–45℃.

[0038] The present invention also discloses a method for preparing the above-mentioned oil fume purification device, comprising the following steps: (1) The substrate is cleaned, dried and pretreated with plasma to increase the surface activation energy of the substrate to ≥72mN / m; (2) A reactive ion etching process is adopted, using SF6 / O2 mixed gas as etching gas. The etching area and etching time are controlled by a mask plate to form a gradient distribution of micron-sized columnar array 41 on the substrate surface along the direction of oil fume flow. (3) After mixing the fluorinated silane oleophobic material with nano-inorganic particles, it is coated onto the etched surface and then thermo-cured to form a nano-scale oleophobic coating 42°. (4) The flexible electrode 5 is attached to both sides of the biomimetic gradient adsorption interface 4, connected to the pulse power module 6, and the electric field strength is configured to decrease in a gradient in the direction of the oil fume airflow. (5) Install the oil collection tank 7 and the PID temperature control module 8.

[0039] In step (2), the flow ratio of SF6 to O2 is 1:2 to 1:4, the etching power is 100–300W, and the air pressure is 5–20Pa. In the micron-scale columnar array 41, the etching depth of the air inlet shroud 1 area is 10–20μm, the etching depth of the guide plate 2 area is 20–35μm, and the etching depth of the inner wall 3 area of ​​the air duct is 35–50μm.

[0040] In step (3), the mass ratio of the fluorinated silane oleophobic material to the nano-inorganic particles is 10:1 to 5:1, the particle size of the nano-inorganic particles is 20–100 nm, the coating method is spraying or impregnation, and the curing temperature is 80–120 °C.

[0041] The electric field strength configuration in step (4) is as follows: electric field strength in area 1 of air inlet hood is 1.5–2kV / cm, electric field strength in area 2 of guide plate is 1.0–1.5kV / cm, electric field strength in area 3 of inner wall of air duct is 0.5–1.0kV / cm, and electric field frequency is 20–80Hz.

[0042] In step (5), the PID temperature control module 8 controls a temperature of 38–42℃.

[0043] Example 1: The oil fume purification device in this embodiment includes: an air inlet hood 1, a guide plate 2, an inner wall of the air duct 3, a biomimetic gradient adsorption interface 4, a flexible electrode 5, a pulse power supply module 6, an oil collection tank 7, and a PID temperature control module 8. The air inlet hood 1 is a rectangular grille, the guide plate 2 has a double-layer staggered structure, the inner wall of the air duct 3 is a circular pipe, and the oil collection tank 7 is elongated. The biomimetic gradient adsorption interface 4 uses a 1.5mm thick aluminum alloy substrate. After pretreatment, the etching area is controlled by a mask plate to form a gradient micron column array. area Column height (μm) Column spacing (μm) Column diameter (μm) Column shape Air intake area 15±2 18±1 12±1 hexagon Deflector area 28±3 12±1 10±1 hexagon Inner wall area of ​​the air duct 42±3 8±1 8±1 hexagon Nano-coating material: Perfluorodecyltrimethoxysilane and nano-SiO2 particles with a diameter of 50nm are mixed at a mass ratio of 8:1. After spraying, the mixture is cured at 120℃ for 40min. The coating thickness is 120nm, the surface roughness Ra=35nm, the contact angle is 153°, and the roll-off angle is 3°.

[0044] The flexible electrodes are made of conductive fiber cloth with a thickness of 0.3 mm and a surface resistivity of 8 Ω / sq, with an electrode spacing of 5 mm. Pulse power output: Air inlet hood area: electric field strength 1.8kV / cm, pulse frequency 60Hz, duty cycle 30%; Guide vane region: electric field strength 1.2kV / cm, pulse frequency 50Hz, duty cycle 30%; The inner wall area of ​​the air duct has an electric field strength of 0.8 kV / cm, a pulse frequency of 40 Hz, and a duty cycle of 25%.

[0045] The PID temperature control module is set to 40℃, with a temperature fluctuation of ±1℃.

[0046] The preparation method is as follows: (1) Substrate pretreatment: The aluminum alloy substrate was ultrasonically cleaned with anhydrous ethanol for 15 min and dried at 80℃ for 30 min; oxygen plasma pretreatment was performed with a power of 150W for 8 min and a surface activation energy of 78mN / m.

[0047] (2) Gradient plasma etching: reactive ion etching equipment, SF6 / O2 flow ratio 1:3, power 200W, gas pressure 10Pa. Etch the air inlet area for 8min, the guide plate area for 15min, and the inner wall area of ​​the air duct for 25min to form a gradient micron column array.

[0048] (3) Nanocomposite coating: Perfluorodecyltrimethoxysilane and nano-SiO2 were mixed at a ratio of 8:1, dispersed in anhydrous ethanol, and ultrasonically dispersed for 30 min. Spray coating was then applied at a coating amount of 12 g / m², and cured at 120℃ for 40 min.

[0049] (4) Electrode layout: The conductive fiber cloth is cut into shape and attached to both sides of the interface at 5mm intervals. The pulse power supply is connected and the gradient electric field parameters are configured.

[0050] (5) Assembly of oil collection tank and temperature control: Install the oil collection tank, the built-in PID temperature control module and PTC heating element, set the temperature to 40℃, and complete the assembly.

[0051] It adopts an oil fume generator with an oil fume particle size distribution of 0.1–5μm, an air volume of 15m³ / min, and continuous operation for 1000 hours.

[0052] Test results: Capture efficiency: 98.5% initially, 98.2% after 1000 hours of operation, with no significant decay; Interface condition: No visible oil residue, surface contact angle still ≥150°; Oil collection tank: Collects approximately 850 mL of oil without solidification or blockage; Energy consumption: The pulse power supply has an average power consumption of 4.2W, the temperature control has an average power consumption of 3.8W, and the total power consumption is 8.0W.

[0053] Example 2 The difference between this embodiment and Embodiment 1 is that a polycarbonate (PC) plastic substrate is used, and the etching process parameters are adjusted accordingly.

[0054] The PC substrate is 2mm thick. The plasma pretreatment uses argon gas, with a power of 120W and a time of 10min. The surface activation energy is 75mN / m.

[0055] With an etching gas flow ratio of SF6 / O2 of 1:2, a power of 150W, and a gas pressure of 8Pa, the etching time is correspondingly extended. Air inlet hood area: etching for 12 min, column height 12 μm, column spacing 18 μm; The flow guide plate area was etched for 22 min, with a column height of 25 μm and a column spacing of 12 μm. Inner wall area of ​​the air duct: etching for 35 min, column height 38 μm, column spacing 8 μm.

[0056] Nano-coating: Perfluorooctyltriethoxysilane and nano-TiO2 are mixed at a mass ratio of 7:1, sprayed and cured at 100℃ for 50 min. The coating thickness is 100 nm, the contact angle is 152°, and the roll-off angle is 4°.

[0057] The electric field parameters are the same as in Example 1, and the median particle size D after agglomeration is... 50 =20μm.

[0058] Performance test results: capture efficiency 97.8%, 97.5% after 1000 hours of operation, no residue on the interface, power consumption 7.5W.

[0059] Example 3

[0060] The difference between this embodiment and Embodiment 1 is that the electric field parameters are adjusted.

[0061] Air inlet shroud area: electric field strength 2.5kV / cm; air guide plate area: electric field strength 2.0kV / cm; Electric field strength in the inner wall area of ​​the air duct: 1.5kV / cm.

[0062] The initial capture efficiency was 94.2%, but it dropped to 87.6% after 200 hours of operation. Disassembly and inspection revealed that the intercolumnar grooves in the inner wall of the air duct were blocked by large-diameter oil droplets, which reduced the interface capture capacity. Some oil droplets were carried away by the airflow and escaped before they could slide off due to gravity.

[0063] This embodiment illustrates that even when using the same biomimetic interface, if the electric field configuration is improper and the particle size after agglomeration exceeds the matching range, the collection efficiency and self-cleaning performance will both decrease.

[0064] Comparative Example 1 (without electric field) differs from Example 1 in that: no low-voltage pulse electric field generator is provided, and only a biomimetic gradient adsorption interface is used.

[0065] Performance testing: The initial collection efficiency was 72.3%. After 100 hours of continuous operation, a slight oil film appeared on the interface surface. After 200 hours, the collection efficiency dropped to 58.6%. After 500 hours, obvious oil deposits appeared on the interface.

[0066] Comparative Example 2 (uniform interface, no gradient) differs from Example 1 in that the biomimetic adsorption interface has a uniform structure and does not employ a gradient design.

[0067] Performance testing: Initial collection efficiency was 91.2%. After 500 hours of continuous operation, oil droplet accumulation appeared in the air inlet hood area, and the collection efficiency in the guide vane area dropped to 82.3%. No obvious accumulation was observed in the inner wall area of ​​the duct, but the collection efficiency was low. Analysis of the causes: Insufficient column height and excessively small column spacing in the air inlet hood area led to premature blockage by large-diameter oil fume particles; excessive column height and excessively large column spacing in the inner wall area of ​​the duct resulted in insufficient interception of condensed oil droplets.

[0068] Comparative Example 3 (without temperature control) differs from Example 1 in that the oil collection tank is not equipped with a temperature control module.

[0069] Performance testing: After 200 hours of continuous operation, some oil droplets in the oil collection tank solidified, resulting in poor flow and a small amount of oil droplets remaining at the bottom edge of the interface. The residue problem was more severe in winter.

[0070] Comparative Example 4 (Temperature Control Deviation) differs from Example 1 in that the temperature control module is set to 60°C.

[0071] Performance testing: Initial collection efficiency was 98.2%. After 300 hours of continuous operation, the contact angle decreased to 142°, the roll-off angle increased to 8°, and an oil film residue appeared at the interface. Analysis of the cause: Long-term high temperature caused thermal aging of the fluorinated silane coating, increasing surface energy and reducing oleophobic properties.

[0072] Summary of Examples and Comparative Examples project Capture efficiency (initial) Capture effect (1000h) Interface status Self-cleaning Example 1 98.5% 98.2% No residue excellent Example 2 97.8% 97.5% No residue excellent Example 3 94.2% 87.6% Local blockage middle Comparative Example 1 72.3% 58.6% Oil buildup Difference Comparative Example 2 91.2% 82.3% Local accumulation middle Comparative Example 3 98.3% 96.8% Bottom residue middle Comparative Example 4 98.2% 91.5% Oil film residue middle As can be seen from the above embodiments and comparative examples, the present invention achieves the technical effects of efficient capture, self-cleaning, and maintenance-free operation through the synergistic effect of the biomimetic gradient adsorption interface, gradient low-voltage pulsed electric field, and temperature control module.

Claims

1. An oil fume purification device, characterized in that, include: Air inlet shroud, air deflector, air duct; A biomimetic gradient adsorption interface is provided on at least part of the surface of the air inlet shroud, the guide plate and the inner wall of the air duct; A low-voltage pulsed electric field generator is deployed on both sides of the biomimetic gradient adsorption interface. And an oil collection trough located at the bottom of the air inlet shroud; The biomimetic gradient adsorption interface is a multi-level gradient micro-nano composite structure, including a bottom micron-level columnar array and an upper nano-level oleophobic coating. The columnar array is gradient-distributed in the direction of oil fume airflow, with the column height in the air inlet hood area being less than the column height in the guide plate area, and the column height in the guide plate area being less than the column height in the inner wall area of ​​the air duct. The electric field strength of the low-voltage pulse electric field generator decreases gradually in the direction of the oil fume airflow. The electric field strength in the air inlet hood area is greater than that in the guide plate area, and the electric field strength in the guide plate area is greater than that in the inner wall area of ​​the air duct.

2. The oil fume purification device according to claim 1, characterized in that, The columnar array has a column height of 10–50 μm, a column spacing of 5–20 μm, and a depth-to-width ratio ≥1:1; the oleophobic coating is a composite coating of fluorinated silane materials and nano-inorganic particles, with a thickness of 50–200 nm and a surface roughness Ra≤50 nm.

3. The oil fume purification device according to claim 1, characterized in that, The low-voltage pulsed electric field generator includes a flexible electrode and a pulsed power supply module. The flexible electrode is a conductive fiber cloth or a conductive flexible film. The electrode spacing is 2–10 mm, the pulse voltage is ≤12 V, the pulse frequency is 10–100 Hz, and the electric field strength is 0.5–2 kV / cm.

4. The oil fume purification device according to claim 1, characterized in that, The biomimetic gradient adsorption interface is inclined at an angle of 5–30°, with the inclination direction facing the oil collection tank; the oil collection tank is equipped with a PID temperature control module, with a heating temperature of 35–45℃.

5. A method for preparing an oil fume purification device as described in any one of claims 1 to 4, characterized in that, Includes the following steps: (1) The substrate is cleaned, dried and pretreated with plasma to increase the surface activation energy of the substrate to ≥72mN / m; (2) Reactive ion etching process is adopted, using SF6 / O2 mixed gas as etching gas, and the etching area and etching time are controlled by a mask to form a gradient distribution of micron-sized columnar array on the substrate surface along the direction of oil fume flow; (3) After mixing the fluorinated silane oleophobic material with nano-inorganic particles, the mixture is coated onto the etched surface and then thermo-cured to form a nano-scale oleophobic coating. (4) The flexible electrode is attached to both sides of the biomimetic gradient adsorption interface, connected to the pulse power module, and the electric field strength is configured to decrease in a gradient in the direction of the oil fume airflow. (5) Install the oil collection tank and PID temperature control module.

6. The preparation method according to claim 5, characterized in that: In step (2), the flow ratio of SF6 to O2 is 1:2 to 1:4, the etching power is 100–300W, and the gas pressure is 5–20Pa. In the micron-scale columnar array, the etching depth of the air inlet hood area is 10–20μm, the etching depth of the guide plate area is 20–35μm, and the etching depth of the inner wall area of ​​the air duct is 35–50μm.

7. The preparation method according to claim 5, characterized in that: In step (3), the mass ratio of the fluorinated silane oleophobic material to the nano-inorganic particles is 10:1 to 5:1, the particle size of the nano-inorganic particles is 20–100 nm, the coating method is spraying or impregnation, and the curing temperature is 80–120 °C.

8. The preparation method according to claim 5, characterized in that, The electric field strength configuration in step (4) is as follows: 1.5–2kV / cm in the air inlet hood area, 1.0–1.5kV / cm in the guide plate area, 0.5–1.0kV / cm in the inner wall area of ​​the air duct, and 20–80Hz pulse frequency.

9. The preparation method according to claim 5, characterized in that, The PID temperature control module in step (5) controls the temperature to be 38–42℃.

Images