Device and method for improving thermal conductivity and insulation performance of insulating paper

Abstract

The present invention provides a device and method for improving the thermal conductivity and insulation properties of insulating paper. Through the activation of a new integrated plasma modification device and an OMCTS / BN mixed solution, a dense silicon oxide film containing BN is deposited and polymerized on the surface of the insulating paper, thereby improving the thermal conductivity, dielectric and insulation properties of the insulating paper. Compared with traditional chemical modification and nano-doping methods, the present invention has a simple operation process, does not produce toxic and harmful substances, the prepared mixed solution can be used continuously, and the plasma treatment effect is uniform. The idea of ​​using OMCTS+OMCTS / BN medium addition to achieve solid, liquid and gas three-state mixed discharge is novel. The uniformity of the electric field, flow field and material field in the discharge space is regulated by the matching design of the gas path and the electrode. It has flexibility, adjustability and scalability in terms of reaction activity, selectivity, scope of application and stability. By precisely controlling the process condition parameters, the comprehensive performance of the insulating paper, such as thermal conductivity, dielectricity and insulation, is improved.

Description

Technical Field

[0001] The present invention belongs to the field of insulating paper modification, and relates to a device and method for improving the thermal conductivity and insulating properties of insulating paper based on plasma surface modification technology. Background Art

[0002] Insulating paper, primarily made of cellulose, is one of the most important insulating materials in electrical equipment and is widely used in transformers, capacitors, motors, and other electrical equipment. As the primary form of insulation for power insulation equipment, the performance of oil-paper insulation directly impacts the safety and stability of the equipment. In actual applications, factors that lead to oil-paper insulation failure include dielectric constant mismatch and thermal aging. During long-term operation, dielectric constant mismatch and uneven electric field strength distribution can lead to charge accumulation at the oil-paper interface, which in severe cases can cause insulation failure. Furthermore, the conductors within the equipment generate heat during operation, and since the insulation paper has poor thermal conductivity, heat accumulation can cause severe temperature rise and functional failure.

[0003] Existing methods for improving the thermal conductivity and insulation performance of insulating paper mainly focus on physical doping and chemical treatment modification.

[0004] 1) Physical doping involves adding highly conductive materials, such as alumina, carbon nanotubes, and graphene, to the insulating paper during its preparation to improve its thermal conductivity. The resulting insulating paper's internal fiber structure forms thermal channels formed by the doped materials, thereby increasing the efficiency of heat conduction within the paper. This method is limited by performance mismatches and processing precision. The addition of certain thermally conductive materials or improper handling can lead to decreased insulation and mechanical properties, making it difficult to meet the demands of industrial efficiency development.

[0005] 2) Chemical treatment involves soaking the insulating paper or mixing the pulp with a chemical solvent containing a thermal conductivity modifier. The chemical solvent can be an alcohol or other suitable organic solvent. This introduces functional groups through a chemical reaction on the insulating paper's surface, improving thermal conductivity. This method allows for customized material selection through the selection of different solvents and modification formulas. However, soaking in chemical solvents can corrode the insulating paper fibers, impairing their mechanical strength and flexibility, and the wastewater poses a risk of environmental pollution.

[0006] 3) Physicochemical composite treatment involves chemically treating the thermal conductivity enhancer nanoparticles and metal oxides, resulting in a large number of functional groups on the particle surface. The chemically modified thermally conductive particles are then mixed into an insulating paper pulp solution and pressed into insulating paper. Due to the large number of functional groups on the particle surface, the particle-doped insulating paper is denser. However, this method has certain limitations in terms of preparation steps, economic costs, process conditions, and operational precision. Summary of the Invention

[0007] 1. Technical problems to be solved:

[0008] How to increase the thermal conductivity of insulating paper while reducing the dielectric constant, thereby suppressing transformer insulation failure and equipment failure caused by overheating.

[0009] 2. Technical solution:

[0010] In order to solve the above problems, the present invention provides a device for improving the thermal conductivity and insulation performance of insulating paper, including a power supply unit, a human-machine interaction control unit, a gas-liquid-solid medium mixing unit, a material processing unit, a motor control unit and a gas cylinder storage unit. The material processing unit includes a high-voltage electrode, a ground electrode, an upper metal column, a lower metal column, a quartz bottle cover, a quartz bottle body, a quartz air inlet pipe and a quartz air outlet pipe. When the insulating paper is processed, the insulating paper is placed at the bottom of the quartz bottle body. The working gas Ar, the liquid medium OMCTS, and the solid particles BN pass through the gas-liquid-solid medium mixing unit, and the evenly mixed three-state reaction substances are connected to the air inlet pipe through the air pipe and enter the quartz bottle body. The side of the air inlet pipe extending into the bottle body and the bottom side of the air outlet pipe 3 are small hole structures. The air flow is evenly dispersed through the small holes of the air inlet pipe, and the air inlet pipes are distributed in four directions around the bottle body, so that the flow field is evenly distributed in the bottle body. The upper metal column has a hole inside, through which the outlet pipe passes, parallel to the interior of the quartz bottle cap. The outlet pipe restricts the flow field at the center of the quartz bottle cap, limiting the gas flow rate due to the small hole in the outlet pipe, ensuring uniform flow distribution. A metal disc high-voltage electrode is fixed above the quartz bottle cap. An upper metal column extends from the center of this metal disc high-voltage electrode. This upper metal column is connected to the power supply unit via a high-voltage line. The quartz bottle cap is connected to the upper platform via an upper support column, which in turn is fixedly connected to the upper insulating column. A ground electrode is fixed to the bottom of the bottle body, below which a lower metal column extends. This lower metal column is fixedly connected to the fixing plate. The fixing plate is connected to the lower platform via a lower support column, which in turn is fixedly connected to the lower insulating column. The motor control unit primarily controls the movement and rotation of the upper insulating column, used to separate or join the quartz bottle cap and body. The motor controls the movement of the upper insulating column toward the lower insulating column by setting interface stress and using a button, ensuring a tight fit between the quartz bottle cap and body. Considering the plasma's need for a sealed air environment, two protrusions are placed beneath the quartz bottle cap. These not only secure the quartz bottle in place but also enhance airtightness and promote uniform flow distribution. A motor controls the rotation of the upper insulating column, which in turn drives the quartz bottle cap, by setting the speed and using a button. During rotation, the rotation of the metal disc high-voltage electrode and the resulting interfacial friction uniformly distribute the material, flow, and electric fields. This uniform interaction of the material, flow, and electric fields improves the uniformity of the insulating paper's modification.

[0011] The gas-liquid-solid medium mixing unit consists of two medium bottles, a mixing bottle, and a magnetic stirring water bath. The first medium bottle contains an OMCTS / BN mixed solution, and the second medium bottle contains pure OMCTS medium. The first, second, and mixing bottles are all placed in a magnetic stirring water bath. The mixing bottle has three gas channels. One channel directly feeds Ar from the gas bottle storage unit into the mixing bottle as the main gas line, providing the working gas. One channel introduces the continuously stirred BN / OMCTS mixed solution, using argon as a carrier gas to carry OMCTS and BN into the mixing bottle. One channel introduces pure OMCTS medium, using argon as a carrier gas, into the mixing bottle. The three gases are thoroughly mixed in the mixing bottle, and the mixed medium is introduced into the reaction device using a homogenizer. The gas flow rates of the three gas channels can be controlled through the human-computer interface. The magnetic stirring water bath allows the temperature of the water bath to be adjusted to influence the saturated vapor pressure of the reaction medium and the solubility of BN in OMCTS, thereby controlling the mixing ratio of OMCTS and BN. Furthermore, the stirring speed can be adjusted to promote the dissolution of BN powder in the OMCTS solution. The combined effects of human-machine interaction, magnetic stirring, and water bath heating ensure uniform mixing of the three phases of the working gas Ar, liquid medium OMCTS, and solid BN particles within the mixing bottle, allowing for the adjustment of the mixing ratio of the three phases of the reaction medium.

[0012] The preparation method of the OMCTS / BN mixed solution in the first medium bottle is as follows: 280-320 mL of OMCTS solution and 8-12 g of BN powder are added to a beaker, placed in a magnetic stirring water bath, and the heating and stirring module is turned on. The mixture is heated to 95-105°C and turned on at 200-400 rpm to accelerate the dissolution of BN, so that BN is quickly dissolved in OMCTS and reaches saturation; after 1.5-2.5 hours, the heating is stopped, the temperature of the water bath is controlled at 22-27°C, the speed is maintained, and the BN powder and OMCTS mixed solvent are placed in the pot for 0.8-1.2 hours to finally obtain the OMCTS and BN mixed solution used in the experiment.

[0013] The human-machine interaction control unit is used to control the gas flow meter to monitor and adjust the gas flow of each gas channel in real time.

[0014] The temperature of pure OMCTS in the second medium bottle was 22-27°C.

[0015] The temperature and speed of the magnetic stirring water bath are controlled by a button switch on the surface. During the ventilation process, stirring can be carried out simultaneously to ensure that BN is saturated and dissolved in the OMCTS solution.

[0016] The lower metal column and the fixing plate are fixed by threaded connection and tightened with screws at the bottom to prevent the upper insulating column from rotating and causing the lower metal column to loosen.

[0017] The power supply unit connected to the metal disk high-voltage electrode is a nanosecond pulse power supply.

[0018] The hole in the upper metal column is tightened and fixed with a ring-shaped fixing clamp to fix the exhaust pipe.

[0019] The present invention also provides a method for improving the thermal conductivity and insulation performance of insulating paper.

[0020] 3.Beneficial effects:

[0021] The present invention utilizes green and environmentally friendly modification technology, does not produce toxic and harmful substances, and the prepared chemical solution can be reused. No specific waste liquid recovery and treatment system is required, which greatly simplifies the modification process and process costs. During the operation of the device, the three fields of spatial electric field, flow field, and material field are evenly distributed, which will not destroy the cellulose structure inside the insulating paper. The plasma treatment effect is uniform, avoiding the situation of uneven thermal conductivity during the use of the insulating paper. After plasma treatment, the surface performance of the insulating paper is covered with a dense silicon oxide film containing BN, while improving the comprehensive performance of the insulating paper such as thermal conductivity, dielectric and insulation, and realizing the dielectric and thermal conductivity coordination of the insulating paper in oil-paper insulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the modification device of the present invention.

[0023] Figure 2 It is a schematic diagram of the plasma modification device.

[0024] Figure 3 It is a schematic diagram of a gas-liquid-solid uniform mixing unit.

[0025] Figure 4 Chemical structural formulas of different components: (a) BN; (b) OMCTS; (c) cellulose insulation paper.

[0026] Figure 5 This is a schematic diagram of the plasma reaction process.

[0027] Explanation of the accompanying symbols: 1. Quartz bottle body; 2. Quartz bottle cover; 3. Quartz air outlet pipe; 4. Metal disk high-voltage electrode; 5. Ground electrode; 6. Lower metal column; 7. Upper support column; 8. Lower support column; 9. Upper platform; 10. Lower platform; 11. Fixed plate; 12. Upper metal column; 13. Quartz air inlet pipe; 14. Upper insulating column; 15. Lower insulating column; 17. Insulating paper. DETAILED DESCRIPTION

[0028] The present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0029] like Figure 1As shown, a device for improving the thermal conductivity and insulation properties of insulating paper based on plasma surface modification technology includes a gas cylinder storage unit, a gas-liquid-solid medium mixing unit, a material processing unit, a motor control unit, a human-machine interaction control unit, and a power supply unit. Each unit works together to achieve multi-condition control integration. The gas cylinder storage unit is mainly responsible for providing working gas and carrier gas for the medium. The human-machine interaction control unit is mainly responsible for managing the gas flow meter, controlling the gas flow in the gas channel, and adjusting the flow rate in real time according to processing requirements. The main purpose of the gas-liquid-solid medium mixing unit is to evenly mix Ar gas, OMCTS liquid, and BN particles.

[0030] The material handling unit, such as Figure 3 As shown, the quartz bottle body 1 and the quartz bottle cap 2 are shown. Insulating paper 17 is placed at the bottom of the quartz bottle body 1. The quartz bottle cap 2 has a hole, and a metal disc high-voltage electrode is fixed above it. An upper metal column 12 extends from the middle of the metal disc high-voltage electrode. The upper metal column 12 has a hole inside. The outlet pipe 3 passes through the hole and is parallel to the inside of the quartz bottle cap 2. The inlet pipes are distributed in four directions around the quartz bottle body to allow the reaction gas to enter the quartz bottle body. The quartz bottle cap 2 is connected to the upper platform 9 via the upper support column 7.

[0031] The working gas Ar, liquid medium OMCTS, and solid particles BN pass through the gas-liquid-solid medium mixing unit, and the evenly mixed three-state reaction substances are connected to the air inlet pipe through the air pipe and enter the quartz bottle body. The air flow is evenly dispersed through the small holes in the extended part of the air inlet pipe. The air inlet pipes are distributed in four directions around the quartz bottle body, so that the flow field is evenly distributed in the quartz bottle body. The air outlet pipe limits the flow field at the center of the quartz bottle cap, and the gas flow rate is limited by the small holes in the air outlet pipe to control the uniform distribution of the flow field.

[0032] A ground electrode 5 is fixed to the bottom of the quartz bottle 1. A lower metal column 6 extends from below the ground electrode 5 and is fixedly connected to a fixing plate 11. The fixing plate 11 is connected to the lower platform 10 via a lower support column 8, which in turn is fixedly connected to a lower insulating column 15. The upper platform 9 is fixedly connected to an upper insulating column 14. Both the upper and lower insulating columns are connected to the motor.

[0033] To ensure uniform electric field, flow field, and tri-phase media distribution within the device, a rotating plate electrode is used as the discharge level to achieve uniform discharge. The combination of the porous structure of the inlet pipe 13 and outlet pipe 3, the rotating friction material of the quartz bottle cap 2, and the sealed, disc-shaped discharge space ensures uniform flow field and uniform distribution of gas, liquid, and solid media. An upper metal post 12 extends from the center of the metal disc high-voltage electrode 4. This upper post 12 is connected to a power supply unit via a high-voltage line. A lower metal post 6 extends from the ground electrode 5 to ground. Plasma discharge occurs within the quartz bottle body 1.

[0034] The entire DBD device is fixed by two brackets. In one embodiment, the two brackets are 50 mm high respectively, and when combined, the total height is 110 mm. The bracket base is a disc with a diameter of 120 mm.

[0035] In one embodiment, the power supply unit is a nanosecond pulse power supply, and the power supply parameters are voltage amplitude 12kV, repetition frequency 5kHz, rising edge 100ns, pulse width 800ns, and falling edge 100ns.

[0036] In one embodiment, Ar gas, OMCTS liquid, and BN solid are uniformly mixed by bubbling and then introduced into an inlet tube 13, which extends 5 mm into the interior of the quartz bottle. An annular tightening clamp is used to secure the outlet tube 3 to prevent it from slipping. The bottom of the quartz tube 3 is parallel to the quartz bottle cap 2. The portion of the inlet tube extending into the interior of the quartz bottle and the bottom of the outlet tube primarily utilize a perforated structure.

[0037] In one embodiment, the quartz bottle cap rotates, the air inlet pipes are distributed around the quartz bottle body, and the air outlet pipe is located in the center of the quartz bottle cap. The small holes in the air inlet pipe and the air outlet pipe have the combined effect of evenly dispersing the mixed gas into the glass container, limiting the flow field and the distribution of gas, liquid, and solid in the space, rotating the friction material, and achieving uniform distribution of the material field, flow field, and electric field after power is applied.

[0038] In one embodiment, the diameter of the BN particles is 5-10 μm, and the diameter of the pores is 100 μm, allowing for stable passage.

[0039] In one embodiment, the total gas flow rate is 1 L / min. The mixed gas finally enters the discharge space of the quartz bottle 1, with a discharge gap of 7 mm. Upon powering up, a mixed-mode discharge with both filaments and diffuse plasma is formed. Under the influence of the gas flow, the filaments rotate, allowing the deposited film to cover the entire area, resulting in a uniform and dense film. This step aims to produce a deposited film covering a large area.

[0040] OMCTS is a liquid at room temperature, while BN is a solid, powdered particle. To achieve uniform distribution of the solid particles within the processing volume, the solid particles are dissolved in a liquid medium and introduced into the processing volume via a carrier gas. By controlling conditions such as gas flow rate, ambient temperature, and stirring speed, uniform gas-liquid-solid mixing is achieved.

[0041] Because OMCTS / BN mixed solutions are difficult to adjust, the present invention utilizes two media bottles: one containing a saturated OMCTS / BN mixed solution and the other containing pure OMCTS. This method allows for regulation not only through temperature and pressure but also optimization using multiple factors, such as OMCTS concentration, giving the reaction system greater flexibility and precision. Combining these two media enhances reaction activity and product selectivity, effectively controlling the target product of a specific reaction. It can adapt to more complex reaction conditions and a variety of reaction mechanisms, and therefore has greater application potential than the single OMCTS / BN method. The core advantage of the OMCTS+OMCTS / BN method lies in its greater flexibility and adjustability, while also offering significant advantages in terms of reaction activity, selectivity, scope of application, and stability.

[0042] In one embodiment, Figure 2 As shown, the gas-liquid-solid medium mixing unit includes two medium bottles and a mixing bottle. The first medium bottle contains an OMCTS / BN mixed solution, and the second medium bottle contains pure OMCTS medium. The medium enters the mixing bottle using argon bubbling, achieving a transportation method where the gas carries the liquid and the liquid carries the solid. Specifically, one gas channel directly enters the mixing bottle from the gas bottle as the main gas channel to provide the working gas. One gas channel enters the constantly stirred BN / OMCTS mixed medium, using argon as a carrier gas to carry OMCTS and BN. One gas channel enters the pure OMCTS medium, also using argon as a carrier gas, which is used to flexibly adjust the BN content in the mixed gas bottle, so that the ratio of gas, liquid, and solid can be flexibly adjusted and evenly mixed.

[0043] In one embodiment, an operating method is provided to achieve different modification effects. The first medium bottle, the second medium bottle, and the gas mixing bottle are all placed in a large magnetic stirring water bath. The temperature and speed can be controlled by buttons on the surface of the machine, and constant temperature and stirring can be controlled simultaneously.

[0044] In one embodiment, the OMCTS / BN mixed solution in the first medium bottle is prepared as follows: 280-320 mL of OMCTS solution and 8-12 g of BN powder are added to a beaker, which is then placed in a magnetic stirring water bath. The heating and stirring modules are turned on, heated to 95-105° C. and 200-400 rpm to accelerate the dissolution of BN, so that BN is quickly dissolved in OMCTS and reaches saturation; heating is stopped after 1.5-2.5 hours, the water bath temperature is controlled at 22-27° C., and the BN powder and OMCTS mixed solvent are left in the pot for 0.8-1.2 hours to obtain the OMCTS and BN mixed solution used in the experiment.

[0045] Because OMCTS / BN mixed solutions are difficult to adjust, the present invention utilizes two media bottles: one containing a saturated OMCTS / BN mixed solution and the other containing pure OMCTS. This method not only allows for regulation via temperature and pressure but also allows for optimization using multiple factors, such as OMCTS concentration, giving the reaction system greater flexibility and precision. Combining the two media enhances reaction activity and product selectivity, effectively controlling the target product of a specific reaction. It can adapt to more complex reaction conditions and a variety of reaction mechanisms, and therefore has greater application potential than the single OMCTS / BN method. The core advantage of the OMCTS+OMCTS / BN method lies in its greater flexibility and adjustability, while also offering significant advantages in terms of reaction activity, selectivity, scope of application, and stability.

[0046] The motor control unit controls the upper insulating column 14 and the lower insulating column 15 to move up and down, and is used to separate and tightly combine the quartz bottle body 1 and the quartz bottle cover 2, and controls the rotational movement of the upper insulating column 14. The motor control unit controls the upper insulating column 14 to move upward, so that the quartz bottle cover 2 and the quartz bottle body 1 are separated. At this time, the insulating paper 17 to be modified can be placed at the bottom of the inside of the quartz bottle body 1, and then the motor control unit controls the upper insulating column 14 to move downward, so that the quartz bottle cover 2 and the quartz bottle body 1 are tightly combined, and the rotation is started to achieve three-field uniformity and uniform treatment effect. After the modification is completed, the motor control unit controls the upper insulating column 14 to stop rotating and move upward, so that the quartz bottle cover 2 and the quartz bottle body 1 are separated. At this time, the insulating paper 17 to be modified can be taken out of the quartz bottle body.

[0047] The present invention also provides a method for improving the thermal conductivity and insulation performance of insulating paper, using the device for improving the thermal conductivity and insulation performance of insulating paper, comprising the following steps:

[0048] Step S01: Turn on the weighing balance power, weigh 8-12g of BN powder, and turn off the power;

[0049] Step S02: Take a clean beaker and pour 280-320 mL of OMCTS solution into it;

[0050] Step S03: Pour BN powder and OMCTS solution into a medium bottle and place it in a magnetic stirring water bath;

[0051] Step S04: Turn on the power of the magnetic stirring water bath;

[0052] Step S05: setting the temperature of one of the water baths to 95-105° C. and the speed to 200-400 rpm;

[0053] Step S06: Press the water bath temperature and stirring switch and stir for 1.5-2.5 hours;

[0054] Step S07: Set the water bath temperature to 22-27°C and cool it down for 0.8-1.2 hours;

[0055] Step S08: Pour 280-320 mL of OMCTS solution into another clean beaker;

[0056] Step S09: Pour the OMCTS solution into a new medium bottle;

[0057] Step S10: Take a clean gas mixing bottle;

[0058] Step S11: placing the pure OMCTS medium bottle and the mixed gas bottle into other pots of the magnetic stirring water bath respectively;

[0059] Step S12: setting the water bath temperature to 22-27°C;

[0060] Step S13: Remove the air pipe and connect the flow meter, pure OMCTS medium bottle, OMCTS / BN medium bottle and mixed gas bottle to the air line.

[0061] Step S14: The long tube of the pure OMCTS medium bottle is connected to one gas line of the flow meter through the air pipe, and the short tube is connected to a long tube of the mixed gas bottle;

[0062] Step S15: The long tube of the OMCTS / BN mixed solution medium bottle is connected to one gas line of the flow meter through the gas pipe, and the short tube is connected to a long tube of the gas mixing bottle;

[0063] Step S16: The long tube of the gas mixing bottle is connected to a gas path of the flow meter through the air pipe, and the short tube is connected to the gas homogenizer to send the mixed medium gas into the quartz bottle;

[0064] Step S17: Turn on the power of the human-computer interaction control unit;

[0065] Step S18: Open the gas flow meter control interface of the human-computer interaction control unit, check whether the gas flow meter is closed, and if not, close it and set the flow rate of each gas path;

[0066] Step S19: Open the gas valve of the Ar cylinder in the gas cylinder storage unit;

[0067] Step S20: First, open the gas line of the pure OMCTS medium bottle and let it flow for 1 minute to fully mix the Ar gas and OMCTS solution in the gas mixing bottle;

[0068] Step S21: reopen the gas line of the OMCTS / BN medium bottle and allow Ar gas to flow for 1 minute to fully mix the Ar gas, OMCTS solution, and BN particles in the gas mixing bottle;

[0069] Step S22: Open the pure Ar gas line again and let it flow for 1 minute to fully mix the Ar gas, OMCTS solution and BN particles in the mixing bottle;

[0070] Step S23: connecting the metal column 12 extending from the metal disk high-voltage electrode 4 to the high-voltage power supply of the power supply unit, and grounding the metal column 6 extending from the ground electrode 5;

[0071] Step S24: Check whether the rotation button of the motor is closed, and turn it off if it is not closed;

[0072] Step S25: Turn on the power of the motor control unit;

[0073] Step S26: controlling the motor to separate the upper insulating column 14 and the lower insulating column 15;

[0074] Step S27: placing the insulating paper 17 to be modified at the bottom of the quartz bottle 1;

[0075] Step S28: setting the motor interface stress to 5-8N;

[0076] Step S29: controlling the motor to tighten the upper insulating column 14 and the lower insulating column 15;

[0077] Step S30: setting the rotation speed of the upper insulating column to 50-60 rpm;

[0078] Step S31: Press the rotation button, and the motor controls the upper insulating column 14 to rotate;

[0079] Step S32: Turn on the power supply unit;

[0080] Step S33: setting the power supply parameters of the nanosecond pulse power supply: voltage amplitude 12 kV, repetition frequency 5 kHz, rising edge 100 ns, pulse width 800 ns, falling edge 100 ns;

[0081] Step S34: power is supplied to perform plasma modification on the insulating paper 17;

[0082] Step S35: modification is completed and power supply is turned off;

[0083] Step S36: Turn off the power supply of the power supply unit;

[0084] Step S37: Turn off the motor rotation button to stop the motor rotation;

[0085] Step S38: Close the upper insulating column 14 and the lower insulating column 15 of the motor and tighten them to control them to separate;

[0086] Step S39: Remove the insulating paper 17. If the modification is continued, return to S27. Otherwise, proceed to S40.

[0087] Step S40: setting the motor interface stress to 0-5N;

[0088] Step S41: controlling the motor to tighten the upper insulating column 14 and the lower insulating column 15;

[0089] Step S42: Turn off the power of the motor control unit;

[0090] Step S43: closing the pure Ar gas line, the gas line of the OMCTS / BN medium bottle, and the gas line of the pure OMCTS medium bottle in sequence;

[0091] Step S44: closing the Ar gas cylinder valve of the gas cylinder storage unit;

[0092] Step S45: releasing the air pressure and removing the air pipe;

[0093] Step S46: Initializing the gas flow meter parameters through the human-computer interaction control unit;

[0094] Step S47: Turn off the power of the human-computer interaction control unit;

[0095] Step S48: Turn off the stirring of the OMCTS / BN medium bottle in the magnetic stirring water bath;

[0096] Step S49: Turn off the heating of the three bottles in the magnetic stirring water bath;

[0097] Step S50: Turn off the power of the magnetic stirring water bath;

[0098] Step S51: Place the pure OMCTS medium bottle, OMCTS / BN medium bottle, and mixed gas bottle in a medium cabinet so that they can be reused next time.

[0099] The present invention relates to an atmospheric pressure DBD with mixed mode discharge of filamentary and diffuse plasma. Figure 4 The chemical molecular structure formulas of the solvent component and the insulating paper component are shown in FIG. Figure 4 a Figure 4 The chemical structure of the cellulose insulation paper studied in this invention is shown in FIG. Figure 4 As shown in c.

[0100] BN, a thermally conductive and insulating material, has low polarity and is insoluble in highly polar liquids such as water and alcohol, but is soluble in less polar liquids. OMCTS itself has a chemically symmetrical structure. Secondly, as a silica-like material, it has low polarity. The mass fraction of BN dissolved in OMCTS was measured using the molar coefficient gravimetric method. The OMCTS liquid was weighed and the filter paper was dried in a vacuum oven at 200°C for one hour. BN powder was poured into the OMCTS, stirred, and allowed to stand. Undissolved BN was filtered out using the dried filter paper. The filtered mixture was weighed, and the BN and filter paper were weighed together. The filtered BN and filter paper were then placed in a vacuum oven at 200°C for one hour. At 200°C, the OMCTS evaporated, leaving behind BN powder. The BN and filter paper were weighed together. The saturated vapor pressure of the BN and OMCTS mixture was calculated using the solution mole fraction and Raoult's law, Equations 1–7. The ratio of the BN and OMCTS mixture in the gas-liquid-solid atmosphere was calculated using Equation 8. At the same time, the saturated vapor pressure is not only affected by the mass of dissolved solids, but also by temperature. By controlling the temperature of the medium environment, the ratio of gas, liquid and solid can also be adjusted.

[0101] (1)

[0102] (2)

[0103] (3)

[0104] (4)

[0105] (5)

[0106] (6)

[0107] (7)

[0108] (8)

[0109] M1—Mass of the original OMCTS fluid

[0110] M2—mass of the BN and OMCTS mixture after filtration

[0111] M3—Mass of undried BN, OMCTS, and filter paper after filtration

[0112] M4—Mass of dried BN and filter paper after filtration

[0113] M5—OMCTS mass volatile

[0114] M6—The mass of OMCTS in the mixture of BN and OMCTS

[0115] M7—The mass of BN in the mixture of BN and OMCTS

[0116] Molar mass of MA-BN

[0117] MB—Molar mass of OMCTS

[0118] Number of moles of NA-BN

[0119] NB—number of moles of OMCTS

[0120] Mole fraction of XA-BN

[0121] P0—saturated vapor pressure of OMCTS

[0122] Saturated vapor pressure of P-BN and OMCTS mixed solution

[0123] C—Media Ratio

[0124] Pa—standard atmospheric pressure

[0125] α—Medium gas flow rate

[0126] β—Total gas flow rate

[0127] The present invention designs a precursor preparation, dissolving boron nitride powder into OMCTS to form a new solvent. Boron nitride powder has excellent thermal conductivity and is often used as a thermal conductive filler doped into the material preparation process. Boron nitride is added to OMCTS, and the boron nitride is tightly surrounded by the OMCTS molecules, increasing the contact area. The two are passed into the plasma reaction device together, and the OMCTS molecules are fragmented into small molecular groups under the action of high-energy active particles. During the movement of the molecular groups, the plasma not only acts on the surface of the insulating paper, but also contacts with the boron nitride powder. The chemical reaction diagram is shown as follows. Figure 5 As shown in the figure, the silicon oxide groups generated by OMCTS fragmentation will form a silicon oxide film on the surface of the boron nitride, which will increase the mechanical strength between the boron nitride powder, the silicon oxide film, and the insulating paper, prevent the boron nitride from falling off, and inhibit the degradation of mechanical properties caused by the addition of boron nitride.

[0128] The invention uses plasma technology to modify insulating paper, achieving an increase in thermal conductivity and a decrease in dielectric constant. The improvements in thermal conductivity and dielectric properties of insulating paper will be explained below, using a schematic diagram of plasma deposition. The inventive method uses dielectric barrier discharge plasma to improve the thermal conductivity of insulating paper while reducing its dielectric constant. A homemade OMCTS / BN solvent is used to introduce inorganic substances such as silanol groups and boron nitride particles onto the surface of the insulating paper. The insulating paper has a physical surface structure with multiple holes and air pockets. During the plasma deposition process, BN and molecular groups deposit a thin silicon oxide film containing BN particles on the surface of the insulating paper. Driven by the airflow, the BN particles and groups can also enter the interior of the insulating paper and undergo chemical reactions, making the interior more compact. The BN particles are distributed on the surface and inside of the insulating paper, forming thermal conduction channels through which heat can be rapidly transferred, resulting in an increase in the thermal conductivity of the insulating paper. Simultaneously, reactions such as polymerization and cross-linking of the BN surface groups result in a denser and more compact thermal bond between the thermally conductive particles. The presence of highly polar groups such as OH on the surface of the insulating paper easily responds to electric fields, resulting in a high dielectric constant for untreated insulating paper. Plasma-deposited films are primarily composed of silanol groups, which have strong inorganic properties. They reduce the highly polar OH groups on the surface and allow them to penetrate the internal structure. The combined effects of the surface and internal structure reduce the polarity of the insulating paper, inhibiting the rotation of cellulose molecules under the influence of the electric field, reducing their ability to respond to electric fields and lowering the dielectric constant.

[0129] Example:

[0130] The plasma treatment time in this scheme is 4 minutes, and the OMCTS / BN gas flow rate is 125 mL / min. Table 1 shows the effect of OMCTS / BN treatment on the insulation paper modification effect.

[0131] Table 1 Comparison of insulation paper properties before and after plasma treatment

[0132]

[0133] When the insulating paper is untreated, its thermal conductivity is 0.77 W / (mK), its dielectric constant is 4.58, its breakdown strength is 20 kV / mm, and its surface flashover voltage is 7.55 kV. After treatment with OMCTS / BN plasma, the thermal conductivity, dielectric constant, breakdown strength, and surface flashover voltage increase to 0.84 W / (mK), 3.70, 21.56 kV / mm, and 8.18 kV, respectively. Furthermore, while the insulating paper's performance improves, the oil-impregnated paper's insulation properties also improve. When the oil-impregnated paper is untreated, its breakdown strength and surface flashover voltage are 26.74 kV / mm and 8.56 kV, respectively. After plasma treatment, these increase to 28.95 kV / mm and 9.28 kV, respectively. As the flow rate increases, the thermal conductivity first decreases and then increases. At 225 mL / min, the thermal conductivity is 0.893 and the dielectric constant is 2.6. In summary, when the OMCTS / BN gas flow rate is 125 mL / min and the treatment time is 4 min, the thermal conductivity of the insulating paper increases by 9.09%, the dielectric constant decreases by 19.21%, the breakdown strength increases by 7.24%, and the surface flashover voltage increases by 8.34%. The breakdown strength and flashover voltage of the oil-impregnated insulating paper increase by 8.26% and 8.41% respectively. The thermal conductivity, dielectric insulation performance, insulation performance and oil-paper insulation performance of the insulating paper are all improved.

Claims

1. A device for improving the thermal conductivity and insulation performance of insulating paper, characterized by: The invention comprises a power supply unit, a human-machine interaction control unit, a gas-liquid-solid medium mixing unit, a material processing unit, a motor control unit and a gas cylinder storage unit. The material processing unit comprises a high-voltage electrode (4), a ground electrode (5), an upper metal column (12), a lower metal column (6), a quartz bottle cover (2), a quartz bottle body (1), a quartz air inlet pipe (13) and a quartz air outlet pipe (3). When the insulating paper is processed, the insulating paper (17) is placed at the bottom of the quartz bottle body (1). The working gas Ar, the liquid medium OMCTS and the solid particles BN pass through the gas-liquid-solid medium mixing unit, and the uniformly mixed three-state reaction substances are connected to the gas homogenizer through the gas pipe, and the air flow is uniformly passed through the air inlet pipe (13) from four directions. Entering the quartz bottle body (1), the side of the air inlet pipe (13) extending into the quartz bottle body (1) and the bottom side of the air outlet pipe (3) are small hole structures. The air flow is evenly dispersed through the small holes of the air inlet pipe (13). The air inlet pipe (13) is distributed in four directions of the quartz bottle body (1), so that the flow field is evenly distributed in the quartz bottle body (1). The upper metal column (12) is provided with a hole inside. The air outlet pipe (3) passes through the hole and is parallel to the quartz bottle cover (2). The air outlet pipe (3) limits the flow field at the center of the quartz bottle cover (2). The gas is limited by the small hole of the air outlet pipe (3) to control the uniform distribution of the flow field. A metal plate (4) is fixed above the quartz bottle cover (2). A hole is extended in the middle of the metal plate (4). An upper metal column (12) is connected to a power supply unit by a high-voltage line. The quartz bottle cap (2) is connected to the upper platform (9) through the upper support column (7), and is further fixedly connected to the upper insulating column (14). A ground electrode (5) is fixed to the bottom of the quartz bottle body (1). A lower metal column (6) extends from the bottom of the ground electrode (5). The lower metal column (6) is fixedly connected to the fixing plate (11). The fixing plate (11) is connected to the lower platform (10) through the lower support column (8), and is further fixedly connected to the lower insulating column (15). The motor control unit mainly controls the movement and rotation of the upper insulating column (14) to separate or combine the quartz bottle cap (2) and the quartz bottle body (1). By setting the interface stress and using a button to control the upper insulating column (14) to move toward the lower insulating column (15), the quartz bottle cap (2) and the quartz bottle body (1) are fitted together. Considering that the plasma requires a closed air environment, there are two protrusions under the quartz bottle cap, which fix the position of the quartz bottle body (1) on the one hand and increase the airtightness and promote the uniform distribution of the flow field on the other hand. The motor controls the rotation of the upper insulating column (14) by setting the speed and using a button to drive the quartz bottle cap (2) to rotate. During the rotation process, the rotation of the high-voltage electrode metal disk high-voltage electrode (4) and the interface friction make the material field, flow field and electric field uniformly distributed. Under the uniform action of the three fields of material field, flow field and electric field, the uniformity of the insulation paper modification is improved.

2. The device for improving the thermal conductivity and insulation performance of insulating paper according to claim 1, characterized in that: The gas-liquid-solid medium mixing unit includes two medium bottles, a mixing bottle and a magnetic stirring water bath. The first medium bottle contains an OMCTS / BN mixed solution, and the second medium bottle contains pure OMCTS medium. The first medium bottle, the second medium bottle and the mixing bottle are all placed in the magnetic stirring water bath. There are three gas channels entering the mixing bottle. One gas channel directly enters the mixing bottle from the gas bottle storage unit as the main gas channel to provide working gas. One gas channel introduces the BN / OMCTS mixed solution that is being stirred, and uses argon as a carrier gas to carry OMCTS and BN into the mixing bottle. One gas channel introduces pure OMCTS medium and uses argon as a carrier gas to enter the mixing bottle. The three gases are fully mixed in the mixing bottle, and the mixed medium is introduced into the reaction device using a homogenizer. The gas flow rates of the three gas lines are controlled by the human-computer interaction interface. The temperature of the magnetic stirring water bath is designed to affect the saturated vapor pressure of the reaction medium and the solubility of BN in OMCTS, thereby controlling the mixing ratio of OMCTS and BN. On the other hand, the stirring speed of the water bath is set to promote the dissolution of BN powder in the OMCTS solution. Under the combined action of human-computer interaction control, magnetic stirring and water bath heating, the working gas Ar, liquid medium OMCTS and solid particle BN are evenly mixed in the mixing bottle, and the mixing ratio of the three-state reaction medium is adjusted.

3. The device for improving the thermal conductivity and insulation performance of insulating paper according to claim 2, characterized in that: The OMCTS / BN mixed solution in the first medium bottle is prepared by adding 280-320 mL of OMCTS solution and 8-12 g of BN powder into a beaker, placing the beaker in a magnetic stirring water bath, turning on the heating and stirring module, heating to 95-105° C. and turning on 200-400 rpm to accelerate the dissolution of BN, so that BN is quickly dissolved in OMCTS and reaches saturation; After 1.5-2.5 hours, the heating was stopped, the temperature of the water bath was controlled at 22-27°C, the rotation speed was maintained, and the BN powder and OMCTS mixed solvent were placed in the pot for 0.8-1.2 hours to finally obtain the OMCTS and BN mixed solution used in the experiment.

4. The device for improving the thermal conductivity and insulation performance of insulating paper according to claim 2, characterized in that: The human-machine interaction control unit is used to control the gas flow meter to monitor and adjust the gas flow of each gas channel in real time.

5. The device for improving the thermal conductivity and insulation performance of insulating paper according to claim 4, characterized in that: The temperature of pure OMCTS in the second medium bottle was 22-27°C.

6. The device for improving the thermal conductivity and insulation performance of insulating paper according to claim 4, characterized in that: The temperature and speed of the magnetic stirring water bath are controlled by the button switch on the surface. During the ventilation process, stirring is carried out simultaneously to ensure that BN is saturatedly dissolved in the OMCTS solution.

7. The device for improving the thermal conductivity and insulation performance of insulating paper according to any one of claims 1 to 6, characterized in that: The lower metal column (6) and the fixing plate (11) are fixed by threaded connection and tightened with screws at the bottom to prevent the upper insulating column (14) from rotating and causing the lower metal column (6) to loosen.

8. The device for improving the thermal conductivity and insulation performance of insulating paper according to any one of claims 1 to 6, characterized in that: The power supply unit connected to the high-voltage electrode metal disk high-voltage electrode (4) is a nanosecond pulse power supply.

9. The device for improving the thermal conductivity and insulation performance of insulating paper according to any one of claims 1 to 6, characterized in that: The hole in the upper metal column is tightened and fixed with an annular fixing clamp to secure the air outlet pipe (3).

10. A method for improving the thermal conductivity and insulation performance of insulating paper, using the device for improving the thermal conductivity and insulation performance of insulating paper according to any one of claims 1 to 9, characterized in that: The following steps are involved: Step S01: Turn on the weighing balance power, weigh 8-12g of BN powder, and turn off the power; Step S02: Take a clean beaker and pour 280-320 mL of OMCTS solution into it; Step S03: Pour BN powder and OMCTS solution into a medium bottle and place it in a magnetic stirring water bath; Step S04: Turn on the power of the magnetic stirring water bath; Step S05: setting the temperature of one of the water baths to 95-105° C. and the speed to 200-400 rpm; Step S06: Press the water bath temperature and stirring switch and stir for 1.5-2.5 hours; Step S07: Set the water bath temperature to 22-27°C and cool it down for 0.8-1.2 hours; Step S08: Pour 280-320 mL of OMCTS solution into another clean beaker; Step S09: Pour the OMCTS solution into a new medium bottle; Step S10: Take a clean gas mixing bottle; Step S11: placing the pure OMCTS medium bottle and the mixed gas bottle into other pots of the magnetic stirring water bath respectively; Step S12: setting the water bath temperature to 22-27°C; Step S13: Remove the air pipe and connect the flow meter, pure OMCTS medium bottle, OMCTS / BN medium bottle and mixed gas bottle to the air line. Step S14: The long tube of the pure OMCTS medium bottle is connected to one gas line of the flow meter through the air pipe, and the short tube is connected to a long tube of the mixed gas bottle; Step S15: The long tube of the OMCTS / BN mixed solution medium bottle is connected to one gas line of the flow meter through the gas pipe, and the short tube is connected to a long tube of the gas mixing bottle; Step S16: The long tube of the gas mixing bottle is connected to the flow meter through the air pipe, and the short tube is connected to the gas homogenizer to send the mixed medium gas into the quartz bottle body (1); Step S17: Turn on the power of the human-computer interaction control unit; Step S18: Open the gas flow meter control interface of the human-computer interaction control unit, check whether the gas flow meter is closed, and if not, close it and set the flow rate of each gas path; Step S19: Open the gas valve of the Ar cylinder in the gas cylinder storage unit; Step S20: First, open the gas line of the pure OMCTS medium bottle and let it flow for 1 minute to fully mix the Ar gas and OMCTS solution in the gas mixing bottle; Step S21: reopen the gas line of the OMCTS / BN medium bottle and allow Ar gas to flow for 1 minute to fully mix the Ar gas, OMCTS solution, and BN particles in the gas mixing bottle; Step S22: Open the pure Ar gas line again and let it flow for 1 minute to fully mix the Ar gas, OMCTS solution and BN particles in the mixing bottle; Step S23: connecting the metal column (12) extending from the metal disk high-voltage electrode (4) to the high-voltage power supply of the power supply unit, and grounding the metal column (6) extending from the ground electrode (5); Step S24: Check whether the rotation button of the motor is closed, and turn it off if it is not closed; Step S25: Turn on the power of the motor control unit; Step S26: controlling the motor to separate the upper insulating column (14) and the lower insulating column (15); Step S27: placing the insulating paper (17) to be modified at the bottom of the quartz bottle (1); Step S28: setting the motor interface stress to 5-8N; Step S29: controlling the motor to tighten the upper insulating column (14) and the lower insulating column (15); Step S30: setting the rotation speed of the upper insulating column to 50-60 rpm; Step S31: Press the rotation button, and the motor controls the upper insulating column (14) to rotate; Step S32: Turn on the power supply unit; Step S33: setting the power supply parameters of the nanosecond pulse power supply: voltage amplitude 12 kV, repetition frequency 5 kHz, rising edge 100 ns, pulse width 800 ns, falling edge 100 ns; Step S34: power is supplied to perform plasma modification on the insulating paper (17); Step S35: modification is completed and power supply is turned off; Step S36: Turn off the power supply of the power supply unit; Step S37: Turn off the motor rotation button to stop the motor rotation; Step S38: closing the upper insulating column (14) and the lower insulating column (15) of the motor and tightening them, controlling the two to separate; Step S39: Take out the insulating paper (17). If the modification is continued, return to S27. Otherwise, proceed to S40. Step S40: setting the motor interface stress to 0-5N; Step S41: controlling the motor to tighten the upper insulating column (14) and the lower insulating column (15); Step S42: Turn off the power of the motor control unit; Step S43: closing the pure Ar gas line, the gas line of the OMCTS / BN medium bottle, and the gas line of the pure OMCTS medium bottle in sequence; Step S44: closing the Ar gas cylinder valve of the gas cylinder storage unit; Step S45: releasing the air pressure and removing the air pipe; Step S46: Initializing the gas flow meter parameters through the human-computer interaction control unit; Step S47: Turn off the power of the human-computer interaction control unit; Step S48: Turn off the stirring of the OMCTS / BN medium bottle in the magnetic stirring water bath; Step S49: Turn off the heating of the three bottles in the magnetic stirring water bath; Step S50: Turn off the power of the magnetic stirring water bath; Step S51: Place the pure OMCTS medium bottle, OMCTS / BN medium bottle, and mixed gas bottle in a medium cabinet so that they can be reused next time.

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