Passive radiation cooling coating for power equipment and preparation method of passive radiation cooling coating

Abstract

The invention discloses a passive radiation cooling coating for power equipment and a preparation method of the passive radiation cooling coating, and belongs to the technical field of functional coatings. The coating is prepared from barium sulfate, titanium dioxide, PVDF-HFP, epoxy resin, a curing agent and absolute ethyl alcohol through ultrasonic dispersion, stirring, coating and curing processes. The average reflectivity in a solar spectrum (0.3-2.5 microns) is greater than 93%, the average emissivity in an atmospheric window (8-13 microns) is greater than 96%, and energy-consumption-free cooling can be realized. Outdoor tests show that the coating can reduce the surface temperature of equipment by 10-16 DEG C, has excellent adhesive force, hydrophobicity and weather resistance, and is suitable for power equipment such as high-voltage wires and transformers.

Description

Technical Field

[0001] This invention relates to the field of polymer-based functional coatings, and in particular to a cooling coating for power equipment based on the principle of passive radiation cooling and its preparation method, which can be applied to the efficient cooling of power equipment such as high-voltage transmission lines and transformers. Background Technology

[0002] High-voltage transmission lines bear the heavy responsibility of long-distance power transmission and are a key component of the power system. However, most transmission lines are used in outdoor environments and face overheating problems caused by sun exposure or high summer temperatures. The lines are prone to power loss and safety hazards due to heat accumulation during power transmission: (1) Increased conductor temperature leads to increased resistance, resulting in additional power loss and reduced transmission efficiency, thus causing economic losses; (2) Increased conductor temperature causes a decrease in mechanical properties and thermal expansion, increasing the risk of conductor sag, which not only threatens the safe and stable operation of the power grid but may also endanger the personal safety of nearby residents.

[0003] Traditional methods for cooling overhead high-voltage transmission lines primarily rely on natural cooling, utilizing air convection or radiation to lower the conductor temperature. This method is suitable for areas with low ambient temperatures and high wind speeds, but is largely ineffective in areas with high ambient temperatures or low wind speeds. Radiation cooling technology, on the other hand, is a novel cooling method that utilizes spectrally selective materials to reflect sunlight in the ultraviolet-visible-near-infrared 0.28-2.5 μm band to reduce energy input, and then radiates heat into outer space through an atmospheric transparency window in the mid-infrared band (8-13 μm) to achieve passive cooling. It boasts advantages of zero energy consumption and zero pollution, showing strong application potential in the thermal management of high-voltage transmission lines. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art.

[0005] The technical solution adopted by this invention to overcome the shortcomings of the prior art is: to provide a passive radiation cooling coating for power equipment with simple preparation process, significant cooling effect, strong adhesion and good weather resistance, and its preparation method, so as to solve the overheating problem of power equipment such as transmission lines and improve power transmission capacity.

[0006] Technical solution To achieve the above objectives, the present invention provides the following technical solution: A passive radiative cooling coating for power equipment, comprising the following components by weight: 1) Barium sulfate (BaSO4) particles: 7 parts 2) Titanium dioxide (TiO2) particles: 2 parts 3) Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP): 1 part 4) Epoxy resin: 0.32 parts 5) Curing agent (isoflurone diamine): 0.8 parts 6) Anhydrous ethanol: 100 parts The barium sulfate particles have a particle size of 200-800 nm.

[0007] The titanium dioxide particles have a particle size of 100-500 nm.

[0008] The poly(vinylidene fluoride-co-hexafluoropropylene) has a weight-average molecular weight of approximately 400 kg / mol, and hexafluoropropylene accounts for 10%.

[0009] The epoxy resin is TDE-85 type epoxy resin.

[0010] The curing agent (isoflurone diamine) is of analytical grade.

[0011] The preparation method of the above-mentioned passive radiative cooling coating for power equipment includes the following steps: 1) Weighing: Weigh out the barium sulfate particles, titanium dioxide particles, poly(vinylidene fluoride-co-hexafluoropropylene), epoxy resin, and curing agent according to the formula ratio, and weigh out the anhydrous ethanol using a graduated cylinder. 2) Ultrasonic dispersion: Mix barium sulfate particles, titanium dioxide particles and anhydrous ethanol, and ultrasonically disperse for 20-40 minutes using an ultrasonic disperser; 3) Mechanical stirring: Vigorously stir the ultrasonically dispersed mixture, adding poly(vinylidene fluoride-co-hexafluoropropylene), epoxy resin and curing agent during the stirring process, and continue stirring for 10-14 hours under sealed conditions; before the end of stirring, add a small amount of film-forming agent as needed to adjust the viscosity of the coating. 4) Coating: Apply the prepared coating to the surface of the power equipment by spraying, brushing or rolling, and control the coating thickness to 50-200 μm; 5) Curing: Place the coated equipment in an oven preheated to 70-90 ℃ to dry and cure for 2-4 hours.

[0012] The cooling coating can be used for cooling equipment such as high-voltage transmission lines, transformer casings, and distribution cabinets.

[0013] Compared with the prior art, the present invention has the following beneficial effects: The method of this invention can reduce the temperature of electrical equipment. Compared with active cooling devices, the method of this invention greatly reduces the energy input for cooling and does not produce a large amount of greenhouse gases; compared with other radiation-cooled coatings, the method of this invention greatly reduces industrial costs and molding difficulty.

[0014] The radiation-cooling coating of the present invention has an average reflectivity of over 93% in the solar spectrum range (0.3-2.5 μm) and an average emissivity of over 96% in the atmospheric window band (8-13 μm), effectively reducing solar radiation absorption while enhancing thermal radiation to outer space, thus achieving passive cooling. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0016] Figure 1 This is a schematic diagram illustrating the passive radiation cooling principle of the coating of the present invention; Figure 2 This is a flowchart of the coating preparation process of the present invention; Figure 3 This is a solar spectral reflectance curve of the coating of the present invention; Figure 4 The infrared emissivity curve of the coating of the present invention is shown. Figure 5 This is a schematic diagram of the cooling test device. Figure 6 Real-time temperature curve for outdoor cooling test; Figure 7 Diagram of a device for simulating conductor cooling test; Figure 8 This is a test diagram of the water contact angle on the coating surface; Figure 9 This is a diagram showing the results of a 180° peel test on the coating. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0019] Unless otherwise specified, all reagents used in the following examples are commercially available products.

[0020] Example 1 Coating formulation (parts by weight): Barium sulfate particles (500 nm): 7 parts; Titanium dioxide particles (300 nm, R-2195 type): 2 parts; Poly(vinylidene fluoride-co-hexafluoropropylene): 1 part; TDE-85 epoxy resin: 0.32 parts; Isoflurane diamine curing agent: 0.8 parts; Anhydrous ethanol: 100 parts.

[0021] Preparation method: (1) Weighing: Use an analytical balance (QL85A) to accurately weigh each component raw material.

[0022] Ultrasonic dispersion: Add 7 parts barium sulfate particles and 2 parts titanium dioxide particles to a beaker, add 100 parts anhydrous ethanol, and use an ultrasonic disperser to ultrasonically disperse at room temperature for 30 minutes with the power set to 100 W.

[0023] (2) Mechanical stirring: Transfer the ultrasonically dispersed mixture to a sealed container equipped with a stir bar, and start the stirrer at a speed of 500 rpm. During stirring, add 1 part poly(vinylidene fluoride-co-hexafluoropropylene), 0.32 parts epoxy resin, and 0.8 parts curing agent. Continue stirring for 12 hours, keeping the container sealed to prevent solvent evaporation. 30 minutes before the end of stirring, add a small amount of anhydrous ethanol (about 5-20 parts) to adjust the viscosity to a suitable level for spraying.

[0024] (3) Coating: Prepare a clean aluminum plate substrate (size 40 mm × 40 mm). Use a spray gun to evenly spray the prepared coating onto the surface of the aluminum plate, controlling the spraying distance to be about 20 cm and the air pressure to be 0.3 MPa. After the first layer is surface dry (about 30 minutes), spray the second layer. The total coating thickness is about 100 μm.

[0025] (4) Curing: Place the sprayed aluminum plate into an oven preheated to 80 ℃, keep it warm for 3 hours, and then let it cool naturally to room temperature.

[0026] Performance testing: The reflectance of the coating in the 0.2-2.5 μm band was tested using a UV-Vis-NIR spectrophotometer (Shimadzu SolidSpec-3700), and the results showed an average reflectance of 93.2%.

[0027] The emissivity of the coating in the 2.5-25 μm band was tested using a Fourier transform infrared spectrometer (ThermoFisher iS50), and the average emissivity in the 8-13 μm band was calculated to be 96.1%.

[0028] Cooling tests were conducted in a clear, cloudless outdoor environment with an ambient temperature of 32 °C and a solar irradiance of approximately 900 W / m². The testing setup consisted of a polystyrene foam box containing a coated aluminum plate and an uncoated control aluminum plate, with a polyethylene film covering the top. Temperature changes were recorded using type K thermocouples. The results showed that the coated aluminum plate was 13.5 °C cooler than the control group.

[0029] The water contact angle of the coating surface was tested using a video optical contact angle meter (OCA-25), and the result was 96.5°, showing good hydrophobicity.

[0030] A 180° peel test was conducted using a universal tensile testing machine (INSTRON-3343), and the peel strength between the coating and the aluminum substrate was measured to be 2.3 N / mm, indicating that the coating has excellent adhesion.

[0031] Example 2: Application on simulated conductors Preparation method: The coating was prepared according to the formulation and method of Example 1.

[0032] Application method: (1) Prepare a simulated wire device: Use a heating resistor with a power of 50 W (about 10 mm in diameter and 200 mm in length) to simulate a current-carrying wire, and connect it to an adjustable power supply to provide constant power.

[0033] (2) Coating spraying: Use a spray gun to evenly spray the coating onto the surface of the heating resistor, spraying 2 layers with a total thickness of about 120μm.

[0034] (3) Curing: Curing in an 80 ℃ oven for 3 hours.

[0035] (4) Outdoor test: The coated resistance thermometer and the uncoated control resistance thermometer were simultaneously powered on, with an input power of 50 W for both. The surface temperature was measured using a PT100 resistance thermometer and a K-type thermocouple. The temperature distribution was monitored using a thermal infrared imager (UTi1260A).

[0036] Test results: Under sunny outdoor conditions (ambient temperature 30 ℃, solar irradiance 850 W / m²), the surface temperature of the coating-coated heating resistor was 68 ℃ at steady state, while the surface temperature of the uncoated control group was 79 ℃, resulting in a cooling effect of 11 ℃. Thermal infrared images showed that the surface temperature distribution of the coating-coated heating resistor was uniform.

[0037] Example 3: Application on actual 110 kV power lines The coating was prepared according to the formulation of Example 1, and the production batch was scaled up to 10 kg.

[0038] The coating was sprayed onto the outer surface of a 5-m long actual 110 kV power line using specialized spraying equipment, applied in three coats with one-hour intervals between each coat, resulting in a total coating thickness of approximately 150 μm. After spraying, the coating was allowed to cure naturally for 24 hours.

[0039] The test results showed that the coating was firmly adhered, with no blistering or cracking; the surface was smooth and even in color; and the coating thickness was uniform with a deviation of less than ±10%.

[0040] Comparative Example 1: Coatings containing only TiO2 and PVDF Coating formulation (parts by weight): Titanium dioxide particles: 1 part; Poly(vinylidene fluoride-co-hexafluoropropylene): 0.5 parts; Anhydrous ethanol: 100 parts.

[0041] Preparation method: Refer to steps (1)-(5) of Example 1, but without adding barium sulfate, epoxy resin and curing agent.

[0042] Performance testing: The reflectance of the coating in the 0.2–2.5 μm wavelength range was measured using a UV-Vis-NIR spectrophotometer (Shimadzu SolidSpec-3700), and the results showed an average reflectance of 89.5%. The emissivity of the coating in the 2.5-25 μm band was tested using a Fourier transform infrared spectrometer (ThermoFisher iS50), and the average emissivity in the 8-13 μm band was calculated to be 93.2%.

[0043] Cooling tests were conducted in a clear, cloudless outdoor environment with an ambient temperature of 32 °C and a solar irradiance of approximately 900 W / m². The testing setup consisted of a polystyrene foam box containing a coated aluminum plate and an uncoated control aluminum plate, with the top covered by a polyethylene film. Temperature changes were recorded using type K thermocouples. The results showed that the coated aluminum plate was 9.8 °C cooler than the control group.

[0044] A 180° peel test was conducted on the coating using a universal tensile testing machine, and the coating adhesion was calculated to be 0.8 N / mm. Slight cracking occurred after the coating cured.

[0045] The results showed that a lack of barium sulfate reduced solar spectral reflectance, and a lack of epoxy resin led to insufficient adhesion and coating cracking.

[0046] Comparative Example 2: Epoxy Resin-Free Coatings Formula: Barium sulfate particles (500 nm): 7 parts; Titanium dioxide particles (300 nm, R-2195 type): 2 parts; Poly(vinylidene fluoride-co-hexafluoropropylene): 1 part; Anhydrous ethanol: 100 parts.

[0047] Preparation: Same as in Experiment 1, but without adding epoxy resin and curing agent.

[0048] Performance testing: A 180° peel test was conducted on the coating using a universal tensile testing machine, and the calculated coating adhesion was 1.1 N / mm. The results showed that coatings lacking epoxy resin and curing agent could be prepared and applied, but after curing, they could be partially peeled off by lightly rubbing with your hand, making them unsuitable for long-term outdoor use.

[0049] Example 4: Weather Resistance Test The coating sample prepared in Example 1 was subjected to accelerated aging test: Experimental methods: UV aging: In the UV aging chamber, UVA-340 lamps were used, with an irradiance of 0.89 W / m² / nm and a temperature of 60 ℃, for continuous irradiation for 500 hours.

[0050] Performance testing: After aging, the average solar spectrum reflectance of the coating was 92.1% (a decrease of 1.1%), the average atmospheric window emissivity was 95.3% (a decrease of 0.8%), the adhesion was 2.1 N / mm (a decrease of 8.7%), and there were no obvious discoloration, chalking, cracking or peeling on the coating surface.

[0051] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to in the method section.

[0052] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A passive radiant cooling coating for power equipment, characterized in that, By mass, it consists of the following components: 7 parts barium sulfate particles, 2 parts titanium dioxide particles, 1 part poly(vinylidene fluoride-co-hexafluoropropylene), 0.32 parts epoxy resin, 0.8 parts curing agent, and 100 parts anhydrous ethanol.

2. The passive radiant cooling coating for power equipment according to claim 1, characterized in that, The barium sulfate particles have a particle size of 200-800 nm; the titanium dioxide particles have a particle size of 100-500 nm; the poly(vinylidene fluoride-co-hexafluoropropylene) has a weight-average molecular weight of approximately 400 kg / mol and a hexafluoropropylene content of 10%; the epoxy resin is TDE-85 type epoxy resin; the curing agent is isophorone diamine; and the film-forming agent is anhydrous ethanol.

3. A method for preparing a passive radiative cooling coating for power equipment as described in any one of claims 1-2, characterized in that, Includes the following steps: (1) Weighing: Weigh out the barium sulfate particles, titanium dioxide particles, poly(vinylidene fluoride-co-hexafluoropropylene), epoxy resin, curing agent and film-forming agent according to the formula ratio. (2) Ultrasonic dispersion: Mix barium sulfate particles, titanium dioxide particles and anhydrous ethanol, and ultrasonically disperse for 20-40 minutes; (3) Stirring: Mechanically stir the ultrasonically dispersed mixture, slowly add poly(vinylidene fluoride-co-hexafluoropropylene), epoxy resin and curing agent during the stirring process, and continue stirring for 10-14 hours under sealed conditions. (4) Coating: Apply the prepared coating to the surface of the power equipment, and control the coating thickness to be 50-200 μm; (5) Curing: Cur the coated equipment at 70-90℃ for 2-4 hours.

4. The preparation method according to claim 3, characterized in that, The ultrasonic dispersion time in step (2) is 30 minutes.

5. The preparation method according to claim 3, characterized in that, The mechanical stirring time in step (3) is 12 hours.

6. The preparation method according to claim 3, characterized in that, In step (4), the coating is applied by spraying, brushing or rolling, using a multi-layer coating method, applying 2-3 layers, with an interval of 30-60 minutes between each layer.

7. The preparation method according to claim 3, characterized in that, In step (5), the curing temperature is 80℃ and the curing time is 3 hours.

8. The application of the passive radiative cooling coating for power equipment as described in any one of claims 1-2 in the cooling of power equipment.

9. The application according to claim 8, characterized in that, The power equipment is a high-voltage transmission line, a transformer casing, or a distribution cabinet.

10. The application according to claim 8, characterized in that, The coating has an average reflectance of ≥90% in the solar spectrum range of 0.3-2.5 μm and an average emissivity of ≥95% in the atmospheric window band of 8-13 μm. Power equipment coated with this coating experiences a temperature reduction of 10-16 ℃ in outdoor environments.

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