Radiation refrigeration film based on phoenix tree batt

Abstract

The invention discloses a radiation refrigeration film based on phoenix tree flocculus, which is prepared from phoenix tree flocculus cellulose and silicon dioxide microspheres according to the mass ratio of 10: 1 through a hot pressing method. Wherein the phoenix tree flocculus cellulose is prepared by performing processes of removing impurities, waxiness, lignin, hemicellulose and the like on phoenix tree flocculus and then drying the phoenix tree flocculus. The silicon dioxide microspheres and the phoenix tree batt which widely exists in the nature and causes environmental pollution and health problems are used as base materials, so that the cost of the preparation process is reduced, and the harm of the phoenix tree batt to the environment and health can be reduced.

Description

Technical Field

[0001] The invention belongs to the field of passive energy utilization, and in particular relates to a radiation cooling film based on Chinese parasol trees. Background Art

[0002] With the acceleration of global industrialization and urbanization, greenhouse gas emissions continue to increase, leading to global warming. The construction industry accounts for about 30%-40% of carbon emissions. In the construction field, air-conditioning systems are large consumers of energy and have a certain impact on the environment during operation. Radiative cooling technology, as a passive cooling technology, can transfer its own heat directly to outer space in the form of thermal radiation through the atmospheric infrared window (8-13μm), thereby reducing the temperature of objects. Because this process does not require any external energy input, it can effectively reduce energy consumption and greenhouse gas emissions, and help alleviate the trend of global warming.

[0003] Among the currently available public reports, Chinese patent CN118186339A discloses a color sub-ambient radiation cooling film and its preparation method. The invention has a multi-layer film structure, including alternately stacked metal layers and non-metal layers, which can achieve three colors, and the average emissivity within 8-13μm can reach 0.98. Chinese patent CN115572399A discloses a passive radiation cooling film and its preparation method. The invention includes a flexible polyethylene terephthalate substrate, a UV-cured adhesive layer and a dipentaerythritol pentaacrylate film layer arranged in sequence from bottom to top, and the average reflectivity within the wavelength range of 0.36-1.2μm can reach 90.7%. Although the above-mentioned public technologies can achieve good radiation cooling effects, metals need to be used as reflective substrates in their preparation process, which is costly, or a variety of chemical reagents are used, which will cause certain pollution to the environment.

[0004] Based on the above problems, the present invention discloses a radiant cooling film based on sycamore fluff. The film uses sycamore fluff, which is widely present in nature and causes environmental pollution and health problems, as raw material. While realizing the radiant cooling function, it reduces the cost of the preparation process and the harm of sycamore fluff to the environment and health. Summary of the invention

[0005] The purpose of the present invention is to provide a radiative cooling film based on sycamore fluff and a preparation method thereof. By combining sycamore fluff cellulose with silica microspheres, the film has high reflectivity in the solar band and high emissivity in the atmospheric window band, thereby achieving radiative cooling.

[0006] The technical solution of the present invention is: a radiative cooling film based on sycamore fluff, characterized in that the radiative cooling film based on sycamore fluff is composed of sycamore fluff cellulose and silica microspheres in a mass ratio of 10:1.

[0007] The above-mentioned radiative cooling film based on Chinese parasol wadding is preferred, wherein the Chinese parasol wadding cellulose is obtained by the following method:

[0008] (a) Removal of impurities from Chinese tung oil floss: soak Chinese tung oil floss in distilled water, with the mass ratio of distilled water to Chinese tung oil floss being 10:1, and stir at a stirring speed of 90-100 rpm for 15-20 minutes to dissolve or separate the impurities in the Chinese tung oil floss to obtain a Chinese tung oil floss suspension;

[0009] Use a glass funnel with filter paper to filter, slowly pour the sycamore floc suspension into the funnel along the glass rod, so that the sycamore floc suspension flows down naturally, and the solid sycamore floc remains on the filter paper, thereby obtaining sycamore flocs with water removed, and put the sycamore flocs with water removed into an oven, and dry them at 40-50°C for 1-2 hours to obtain dried sycamore flocs;

[0010] (b) Removal of wax from Chinese parasol trees: Grind dried Chinese parasol trees into fine powder, roll filter paper into a cylindrical shape, seal the bottom of the filter paper and open the top, and put the fine powder of Chinese parasol trees into the cylinder to obtain a filter paper cylinder filled with fine powder of Chinese parasol trees;

[0011] Add a benzene-ethanol mixture with a volume ratio of 2:1 as a solvent into the distillation flask to 1 / 2-2 / 3 of the volume of the distillation flask, wherein the mass ratio of the benzene-ethanol mixture to the tung oil linden fine powder in the filter paper tube is 20:1-50:1;

[0012] Put the filter paper tube filled with fine powder of Chinese parasol floss into the extraction tube. The height of the filter paper tube should be lower than the top of the extraction tube. Then connect the extraction tube and the condenser. Make sure that the interface is well sealed. The water inlet and the water outlet of the condenser are connected to the circulating cooling water device. The water inlet of the condenser is at the bottom of the condenser, and the water outlet of the condenser is at the top of the condenser to ensure a good condensation effect.

[0013] The distillation flask is heated to evaporate the solvent. The solvent vapor rises through the steam conduit and enters the inner tube of the condenser. It is cooled and liquefied into droplets in the inner tube of the condenser. The droplets drip from the inner tube of the condenser into the filter paper cylinder containing the fine powder of Chinese parasol floss, dissolving the wax in the fine powder of Chinese parasol floss. At the same time, the solvent flows into the filter paper cylinder and penetrates into the extraction tube from the filter paper cylinder. When the solvent liquid level in the extraction tube is higher than the highest point of the siphon tube, the solvent is siphoned back into the distillation flask together with the wax extracted from the fine powder of Chinese parasol floss in the filter paper cylinder. The extraction process lasts for 6-8 hours to remove the wax in the Chinese parasol floss component.

[0014] After the entire extraction device is cooled, the extracted tung oil fine powder in the filter paper tube is placed in an oven and dried at 40-50°C for 1-2 hours to obtain tung oil with the wax removed;

[0015] (c) Removal of lignin from tung oil cotton wool: soaking the tung oil cotton wool from which the wax has been removed in a mixed solution containing 1-3% hydrogen peroxide and 1-2% sodium hydroxide, wherein the mass ratio of the mixed solution of hydrogen peroxide and sodium hydroxide to the tung oil cotton wool from which the wax has been removed is 10:1-20:1, stirring at a speed of 100-300 rpm for 5-10 minutes at a temperature of 50-60° C., and then standing for 30-45 minutes, and repeating the stirring and standing process for 2-3 hours to remove the lignin in the tung oil cotton wool components, thereby obtaining tung oil cotton wool from which the wax and lignin have been removed;

[0016] (d) Removal of hemicellulose from tung oil cotton wool: soak the tung oil cotton wool from which wax and lignin have been removed in a 2-3% sodium hydroxide solution, wherein the mass ratio of the sodium hydroxide solution to the tung oil cotton wool from which wax and lignin have been removed is 10:1-20:1, and stir at a speed of 200-400 rpm for 30-45 minutes at a temperature of 80-90° C., and then stand for 10-15 minutes, and repeat the stirring and standing process for 1-2 hours to remove the hemicellulose from the tung oil cotton wool components, thereby obtaining tung oil cotton wool from which wax, lignin and hemicellulose have been removed;

[0017] (e) Drying of tung oil cellulose: rinse the tung oil cellulose with distilled water to remove wax, lignin and hemicellulose until the pH value of the rinse solution is 6.5-7.5 to obtain a tung oil cellulose suspension, filter the suspension using a glass funnel and filter paper to obtain tung oil cellulose with water removed, place the tung oil cellulose with water removed in an oven, and dry it at 40-50°C for 1-2 hours to obtain tung oil cellulose.

[0018] The present invention also provides a method for preparing the above-mentioned radiative cooling film based on Chinese parasol trees, and the specific steps are as follows:

[0019] (a) mixing tung oil cellulose and silica microspheres in a mass ratio of 10:1, and adding the mixture into a beaker containing distilled water, wherein the mass ratio of distilled water to the mixture of tung oil cellulose and silica microspheres is 10:1-20:1, and stirring the mixture for 7-8 hours with a stirrer at a stirring speed of not less than 2000 rpm to ensure that the tung oil cellulose and silica microspheres are uniformly dispersed in the distilled water;

[0020] (b) A mixture of tung oil cellulose, silica microspheres and distilled water was vacuum filtered using a vacuum filter for 10-12 hours, and the tung oil-based radiative cooling film was obtained by hot pressing at 80-100° C. for 12 hours.

[0021] The above-mentioned sycamore fluff-based radiation cooling film is preferred, characterized in that the reflectivity of the radiation cooling film is not less than 90% in the solar band, and the emissivity of the radiation cooling film is not less than 85% in the atmospheric window band.

[0022] The above-mentioned sycamore cotton-based radiation cooling film is preferred, characterized in that the particle size of the silica microspheres is 2-8 μm.

[0023] The above-mentioned radiative cooling film based on Chinese parasol trees is preferred, characterized in that the thickness of the radiative cooling film is 100-200 μm.

[0024] The circulating cooling water device of the present invention comprises: a constant temperature water tank and a water pump;

[0025] Among them, the constant temperature water tank, water pump and condenser are connected by a hose; the circulating cooling water flows in a closed loop composed of the constant temperature water tank, water pump and condenser; the circulating cooling water flows in the outer tube of the condenser, cools the solvent vapor in the inner tube of the condenser, and condenses the solvent vapor into solvent droplets; the temperature of the circulating cooling water at the water inlet of the condenser is maintained at 5-15°C.

[0026] The extraction device of the present invention comprises: a distillation flask, an extraction tube, a condenser, an inner tube, an outer tube, a water inlet of the condenser, a water outlet of the condenser, a steam conduit, and a siphon.

[0027] The present invention has the following advantages and beneficial effects:

[0028] The radiant cooling film based on sycamore fluff of the present invention utilizes silica microspheres and sycamore fluff that is widely present in nature and causes environmental pollution and health problems as a base material, which not only reduces the cost of the preparation process, but also reduces the harm of sycamore fluff to the environment and health; at the same time, the film preparation process is simple and is convenient for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings required for describing the embodiments.

[0030] Figure 1 It is a structural schematic diagram of a radiation cooling film based on Chinese parasol trees in the present invention.

[0031] Figure 2 It is a schematic diagram of the connection between the entire extraction device and the circulating water cooling device of an embodiment of the present invention.

[0032] Figure 1 and Figure 2The invention comprises: tung oil cellulose 1, silicon dioxide microspheres 2, filter paper tube 21, distillation flask 22, extraction tube 23, condenser 24, inner tube 2401, outer tube 2402, condenser water inlet 25, condenser water outlet 26, steam conduit 27, siphon 28, constant temperature water tank 2901 and water pump 2902. DETAILED DESCRIPTION

[0033] The technical solution of the embodiment of the present invention is described in detail below with reference to the accompanying drawings.

[0034] In an embodiment of the present invention, the radiation cooling film based on Chinese parasol fibers is as follows: Figure 1 As shown, it includes tung oil cellulose 1 and silicon dioxide microspheres 2, and the tung oil cellulose 1 and the silicon dioxide microspheres 2 are composed in a mass ratio of 10:1.

[0035] The sycamore cellulose used is extracted from the collected sycamore cellulose by the following method:

[0036] (a) Removal of impurities from Chinese tung oil floss: soak Chinese tung oil floss in distilled water, with the mass ratio of distilled water to Chinese tung oil floss being 10:1, and stir at a stirring speed of 90-100 rpm for 15-20 minutes to dissolve or separate the impurities in the Chinese tung oil floss to obtain a Chinese tung oil floss suspension;

[0037] Use a glass funnel with filter paper to filter, slowly pour the sycamore floc suspension into the funnel along the glass rod, so that the sycamore floc suspension flows down naturally, and the solid sycamore floc remains on the filter paper, thereby obtaining sycamore flocs with water removed, and put the sycamore flocs with water removed into an oven, and dry them at 40-50°C for 1-2 hours to obtain dried sycamore flocs;

[0038] (b) Removal of wax from Chinese parasol trees: Grind dried Chinese parasol trees into fine powder, roll filter paper into a cylindrical shape, seal the bottom of the filter paper and open the top, and put the fine powder of Chinese parasol trees into the cylinder to obtain a filter paper cylinder 21 filled with fine powder of Chinese parasol trees;

[0039] Add a benzene-ethanol mixture with a volume ratio of 2:1 as a solvent into the distillation flask 22 to 1 / 2-2 / 3 of the volume of the distillation flask 22, wherein the mass ratio of the benzene-ethanol mixture to the tung oil fine powder in the filter paper tube 21 is 20:1-50:1;

[0040] Put the filter paper tube 21 filled with fine powder of Chinese parasol floss into the extraction tube 23. The height of the filter paper tube 21 should be lower than the top of the extraction tube 23. Then connect the extraction tube 23 and the condenser 24. Make sure that the interface is well sealed. The water inlet 25 and the water outlet 26 of the condenser are connected to the circulating cooling water device. The water inlet 25 of the condenser is at the lower part of the condenser 24, and the water outlet 26 of the condenser is at the upper part of the condenser 24 to ensure a good condensation effect.

[0041] The distillation flask 22 is heated to evaporate the solvent. The solvent vapor rises through the steam conduit 27 and enters the inner tube 2401 of the condenser 24. The solvent vapor is cooled and liquefied into droplets in the inner tube 2401 of the condenser 24. The droplets drip from the inner tube 2401 of the condenser 24 into the filter paper cylinder 21 containing the fine powder of Chinese parasol floss, dissolving the wax in the fine powder of Chinese parasol floss. At the same time, the solvent flows into the filter paper cylinder 21 and penetrates into the extraction tube 23 from the filter paper cylinder 21. When the solvent liquid level in the extraction tube 23 is higher than the highest point of the siphon tube 28, the solvent is siphoned back into the distillation flask 22 together with the wax extracted from the fine powder of Chinese parasol floss in the filter paper cylinder 21. The extraction process lasts for 6-8 hours to remove the wax in the Chinese parasol floss component.

[0042] After the entire extraction device is cooled, the extracted tung oil fine powder in the filter paper tube 21 is placed in an oven and dried at 40-50° C. for 1-2 hours to obtain tung oil with the wax removed;

[0043] (c) Removal of lignin from tung oil cotton wool: soaking the tung oil cotton wool from which the wax has been removed in a mixed solution containing 1-3% hydrogen peroxide and 1-2% sodium hydroxide, wherein the mass ratio of the mixed solution of hydrogen peroxide and sodium hydroxide to the tung oil cotton wool from which the wax has been removed is 10:1-20:1, stirring at a speed of 100-300 rpm for 5-10 minutes at a temperature of 50-60° C., and then standing for 30-45 minutes, and repeating the stirring and standing process for 2-3 hours to remove the lignin in the tung oil cotton wool components, thereby obtaining tung oil cotton wool from which the wax and lignin have been removed;

[0044] (d) Removal of hemicellulose from tung oil cotton wool: soak the tung oil cotton wool from which wax and lignin have been removed in a 2-3% sodium hydroxide solution, wherein the mass ratio of the sodium hydroxide solution to the tung oil cotton wool from which wax and lignin have been removed is 10:1-20:1, and stir at a speed of 200-400 rpm for 30-45 minutes at a temperature of 80-90° C., and then stand for 10-15 minutes, and repeat the stirring and standing process for 1-2 hours to remove the hemicellulose from the tung oil cotton wool components, thereby obtaining tung oil cotton wool from which wax, lignin and hemicellulose have been removed;

[0045] (e) Drying of tung oil cellulose: rinse the tung oil cellulose with distilled water to remove wax, lignin and hemicellulose until the pH value of the rinse solution is 6.5-7.5 to obtain a tung oil cellulose suspension, filter the suspension using a glass funnel and filter paper to obtain tung oil cellulose with water removed, put the tung oil cellulose with water removed into an oven, and dry it at 40-50°C for 1-2 hours to obtain tung oil cellulose 1.

[0046] The method for preparing a radiative cooling film based on Chinese parasol fluff comprises the following steps:

[0047] (a) mixing the tung oil cellulose 1 and the silica microspheres 2 in a mass ratio of 10:1, and adding the mixture into a beaker filled with distilled water, wherein the mass ratio of the distilled water to the mixture of the tung oil cellulose 1 and the silica microspheres 2 is 10:1-20:1, and stirring the mixture with a stirrer at a stirring speed of not less than 2000 rpm for 7-8 hours to ensure that the tung oil cellulose 1 and the silica microspheres 2 are uniformly dispersed in the distilled water;

[0048] (b) A mixture of tung oil cellulose 1, silica microspheres 2 and distilled water is vacuum filtered using a vacuum filter for 10-12 hours, and the tung oil-based radiative cooling film is obtained by hot pressing at 80-100° C. for 12 hours.

[0049] The obtained radiation cooling film based on sycamore fluff is characterized in that the reflectivity of the radiation cooling film is not less than 90% in the solar band, and the emissivity of the radiation cooling film is not less than 85% in the atmospheric window band.

[0050] The obtained radiative cooling film based on Chinese parasol trees is characterized in that the particle size of the silica microspheres is 2-8 μm.

[0051] The obtained radiation cooling film based on Chinese parasol trees is characterized in that the thickness of the radiation cooling film is 100-200 μm.

[0052] The extraction device used includes: a distillation flask 22, an extraction tube 23, a condenser 24, an inner tube 2401, an outer tube 2402, a condenser water inlet 25, a condenser water outlet 26, a steam conduit 27, and a siphon 28.

[0053] The circulating cooling water device used includes: a constant temperature water tank 2901 and a water pump 2902;

[0054] Among them, the constant temperature water tank 2901, the water pump 2902, and the condenser 24 are connected by a hose; the circulating cooling water flows in a closed loop formed by the constant temperature water tank 2901, the water pump 2902, and the condenser 24;

[0055] The circulating cooling water flows in the outer tube 2402 of the condenser 24, cooling the solvent vapor in the inner tube (2401) of the condenser 24, so that the solvent vapor is condensed into solvent droplets; the temperature of the circulating cooling water at the water inlet 25 of the condenser is maintained at 5-15°C.

[0056] The specific working process of the circulating cooling water device is as follows:

[0057] The cooling water flows from the condenser water inlet 25 into the outer tube 2402 of the condenser 24, flows in the outer tube 2402 of the condenser 24, cools the solvent vapor in the inner tube 2401 of the condenser 24, and condenses the solvent vapor into solvent droplets. After being heated, the cooling water flows out from the condenser water outlet 26, flows into the constant temperature water tank 2901 along the pipeline, and the cooling water is cooled to 5-15°C in the constant temperature water tank; the cooling water cooled to 5-15°C flows out of the constant temperature water tank 2901, flows into the water pump 2902, and after being pressurized in the water pump 2902, flows into the condenser water inlet 25 again along the pipeline, completing the circulation of the cooling water.

[0058] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A radiation cooling film based on Chinese parasol trees, characterized in that: The radiation cooling film is composed of tung oil cellulose (1) and silicon dioxide microspheres (2) in a mass ratio of 10:1; The sycamore cellulose is prepared by the following method: (a) Removal of impurities from Chinese tung oil floss: soak Chinese tung oil floss in distilled water, with the mass ratio of distilled water to Chinese tung oil floss being 10:1, and stir at a stirring speed of 90-100 rpm for 15-20 minutes to dissolve or separate the impurities in the Chinese tung oil floss to obtain a Chinese tung oil floss suspension; Use a glass funnel with filter paper to filter, slowly pour the sycamore floc suspension into the funnel along the glass rod, so that the sycamore floc suspension flows down naturally, and the solid sycamore floc remains on the filter paper, thereby obtaining sycamore flocs with water removed, and put the sycamore flocs with water removed into an oven, and dry them at 40-50°C for 1-2 hours to obtain dried sycamore flocs; (b) Removal of wax from Chinese parasol trees: Grind dried Chinese parasol trees into fine powder, roll filter paper into a cylindrical shape, seal the bottom of the filter paper and open the top, and put the fine powder of Chinese parasol trees into the cylinder to obtain a filter paper cylinder (21) filled with fine powder of Chinese parasol trees; A benzene-ethanol mixture with a volume ratio of 2:1 is added as a solvent into the distillation flask (22) to 1 / 2-2 / 3 of the volume of the distillation flask (22), wherein the mass ratio of the benzene-ethanol mixture to the tung oil floss fine powder in the filter paper tube (21) is 20:1-50:1; Place the filter paper tube (21) filled with the fine powder of Chinese parasol floss into the extraction tube (23). The height of the filter paper tube (21) should be lower than the top of the extraction tube (23). Then connect the extraction tube (23) and the condenser (24). Ensure that the interface is well sealed. The water inlet (25) and the water outlet (26) of the condenser are connected to a circulating cooling water device. The water inlet (25) of the condenser is at the lower part of the condenser (24), and the water outlet (26) of the condenser is at the upper part of the condenser (24) to ensure a good condensation effect. The distillation flask (22) is heated to evaporate the solvent. The solvent vapor rises through the steam conduit (27) and enters the inner tube (2401) of the condenser (24). The solvent vapor is cooled and liquefied into droplets in the inner tube (2401) of the condenser (24). The droplets drip from the inner tube (2401) of the condenser (24) into the filter paper cylinder (21) containing the tung oil fine powder, dissolving the wax in the tung oil fine powder. The solvent flows into the filter paper cylinder (21) and then penetrates into the extraction tube (23) from the filter paper cylinder (21). When the solvent liquid level in the extraction tube (23) is higher than the highest point of the siphon tube (28), the solvent is siphoned back into the distillation flask (22) together with the wax extracted from the tung oil fine powder in the filter paper cylinder (21). The extraction process lasts for 6-8 hours to remove the wax in the tung oil components. After the entire extraction device has cooled, the extracted tung oil floss fine powder in the filter paper tube (21) is placed in an oven and dried at 40-50° C. for 1-2 hours to obtain tung oil floss with the wax removed; (c) Removal of lignin from tung oil cotton wool: soaking the tung oil cotton wool from which the wax has been removed in a mixed solution containing 1-3% hydrogen peroxide and 1-2% sodium hydroxide, wherein the mass ratio of the mixed solution of hydrogen peroxide and sodium hydroxide to the tung oil cotton wool from which the wax has been removed is 10:1-20:1, stirring at a speed of 100-300 rpm for 5-10 minutes at a temperature of 50-60° C., and then standing for 30-45 minutes, and repeating the stirring and standing process for 2-3 hours to remove the lignin in the tung oil cotton wool components, thereby obtaining tung oil cotton wool from which the wax and lignin have been removed; (d) Removal of hemicellulose from tung oil cotton wool: soak the tung oil cotton wool from which wax and lignin have been removed in a 2-3% sodium hydroxide solution, wherein the mass ratio of the sodium hydroxide solution to the tung oil cotton wool from which wax and lignin have been removed is 10:1-20:1, and stir at a speed of 200-400 rpm for 30-45 minutes at a temperature of 80-90° C., and then stand for 10-15 minutes, and repeat the stirring and standing process for 1-2 hours to remove the hemicellulose from the tung oil cotton wool components, thereby obtaining tung oil cotton wool from which wax, lignin and hemicellulose have been removed; (e) Drying of tung oil cellulose: rinse the tung oil cellulose to remove wax, lignin and hemicellulose with distilled water until the pH value of the rinse solution is 6.5-7.5 to obtain a tung oil cellulose suspension, filter the suspension using a glass funnel with filter paper to obtain tung oil cellulose with water removed, put the tung oil cellulose with water removed into an oven, and dry it at 40-50°C for 1-2 hours to obtain tung oil cellulose (1); The method for preparing the radiative cooling film based on Chinese parasol trees has the following specific steps: (a) mixing tung oil cellulose (1) and silica microspheres (2) in a mass ratio of 10:1, and adding the mixture into a beaker containing distilled water, wherein the mass ratio of the distilled water to the mixture of tung oil cellulose (1) and silica microspheres (2) is 10:1-20:1, and stirring the mixture with a stirrer at a stirring speed of not less than 2000 rpm for 7-8 hours to ensure that the tung oil cellulose (1) and silica microspheres (2) are uniformly dispersed in the distilled water; (b) A mixture of tung oil cellulose (1), silica microspheres (2) and distilled water is vacuum filtered using a vacuum filter for 10-12 hours, and the tung oil-based radiative cooling film is obtained by hot pressing at 80-100° C. for 12 hours.

2. A radiative cooling film based on Chinese parasol trees as claimed in claim 1, characterized in that: In the solar band, the reflectivity of the radiation cooling film is not less than 90%, and in the atmospheric window band, the emissivity of the radiation cooling film is not less than 85%.

3. The radiative cooling film based on Chinese parasol trees as claimed in claim 1, characterized in that: The particle size of the silica microspheres (2) is 2-8 μm.

4. The radiative cooling film based on Chinese parasol trees as claimed in claim 1, characterized in that: The thickness of the radiation cooling film is 100-200 μm.

5. The radiative cooling film based on Chinese parasol trees as claimed in claim 1, characterized in that: The circulating cooling water device comprises: a constant temperature water tank (2901) and a water pump (2902); The constant temperature water tank (2901), the water pump (2902), and the condenser (24) are connected via a hose; the circulating cooling water flows in a closed loop formed by the constant temperature water tank (2901), the water pump (2902), and the condenser (24); The circulating cooling water flows in the outer tube (2402) of the condenser (24), cools the solvent vapor in the inner tube (2401) of the condenser (24), and condenses the solvent vapor into solvent droplets; the temperature of the circulating cooling water at the water inlet (25) of the condenser is maintained at 5-15°C.

6. The radiative cooling film based on Chinese parasol trees as claimed in claim 1, characterized in that: The entire extraction device comprises: a distillation flask (22), an extraction tube (23), a condenser (24), an inner tube (2401), an outer tube (2402), a condenser water inlet (25), a condenser water outlet (26), a steam conduit (27), and a siphon (28).

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