Composite thermochromic window with dual-band dynamic regulation and control function

Abstract

The invention discloses a composite thermochromic window with a dual-band dynamic regulation and control function. The composite thermochromic window comprises a first transparent substrate, a tungsten-doped vanadium dioxide film, a second transparent substrate and a hydrogel layer. The tungsten-doped vanadium dioxide film is deposited on the upper surface of the first transparent substrate, and the phase transition temperature is 25-32 DEG C; the hydrogel layer is thermo-sensitive poly (N-isopropylacrylamide) and is encapsulated between the two transparent substrates, and the low critical phase transition temperature is 32 + / -2 DEG C. When the temperature is lower than 25 DEG C, the infrared transmittance of the tungsten-doped vanadium dioxide film is larger than or equal to 75%, and the visible light scattering rate of the hydrogel layer is smaller than or equal to 10%; when the temperature is higher than 32 DEG C, the near-infrared transmittance of the tungsten-doped vanadium dioxide film is reduced to the minimum value, and the visible light scattering rate of the hydrogel layer is increased to 35% or above. Compared with the prior art, the system and the method have the advantages that dual-band dynamic regulation and control of visible light and near-infrared light are achieved, the indoor photo-thermal environment can be automatically regulated according to the environment temperature, and the building energy utilization efficiency is improved.

Description

Technical Field

[0001] The invention relates to building energy saving and radiation cooling technology, and in particular to a composite thermochromic window with a dual-band dynamic regulation function. Background Art

[0002] With the intensification of global climate change and energy crisis, building energy conservation has become an important way to achieve the "dual carbon" goal. In building energy consumption, windows are the weak link in the building envelope, accounting for about 40% of building energy consumption. Therefore, the development of energy-saving windows with intelligent control functions is of great significance to reducing building energy consumption.

[0003] Traditional static windows cannot automatically adjust their optical properties according to ambient temperature changes, resulting in indoor overheating in summer and heat loss in winter, increasing the building's cooling and heating loads. To solve this problem, thermochromic smart windows came into being. Vanadium dioxide (VO 2 ) As a typical thermochromic material, it undergoes a metal-insulator phase transition at a specific temperature, thereby changing its transmittance to near-infrared light, and has become a hot topic in smart window research.

[0004] Tungsten-doped vanadium dioxide (W-VO 2 ) Thermochromic films have attracted much attention due to their adjustable phase transition temperature. CN107188426A discloses a tungsten-doped vanadium dioxide thermochromic film and a preparation method thereof, which adopts magnetron sputtering technology to prepare a vanadium pentoxide / metal tungsten / vanadium pentoxide mixed film, and obtains a tungsten-doped vanadium dioxide film by inert atmosphere treatment, so that its phase transition temperature is close to room temperature, while maintaining a high visible light transmittance and infrared control efficiency. CN111116050A proposes a tungsten-doped vanadium dioxide film with a film thickness of 20-40nm, a phase transition temperature of 25-45℃, and a visible light transmittance of 50-60%. It is prepared by a method of simultaneous mixed sputtering of a metal vanadium target and a tungsten target, which has a simple process and is convenient for large-scale production.

[0005] However, a single VO 2 Thermochromic windows have obvious defects: low visible light transmittance, high phase transition temperature, and limited solar modulation capability. CN114620945A proposes a highly transparent vanadium dioxide-based thermochromic smart window and its preparation method. 2 The micro-nano particle layer increases the visible light transmittance of the window. 2 It is still difficult for materials to effectively control visible light and near-infrared light at the same time.

[0006] In order to achieve full-band control of sunlight, researchers began to explore composite material systems. CN114163574A discloses a method for preparing a vanadium dioxide film / PAM-PNIPAM hydrogel composite thermochromic device. 2 The method adds N-isopropylacrylamide monomer (NIPAM), N,N'-methylenebisacrylamide (BIS) and potassium persulfate (KPS) into deionized water, obtains PNIPAM microgel by continuous feeding, and then polymerizes acrylamide in situ in the PNIPAM microgel. 2 A gel state is formed between the glass of the film.

[0007] Although the existing technology has made some progress, there are still the following problems: First, the existing single VO 2 Although thermochromic windows can regulate near-infrared light transmittance, visible light transmittance is generally low, the phase transition temperature is usually higher than the human body's comfortable temperature, and the solar modulation capacity is limited; secondly, although hydrogel-based thermochromic windows have visible light modulation capabilities, they usually show limited near-infrared modulation capabilities; thirdly, most smart windows in the existing technology can only regulate a single band and cannot dynamically adjust the transmittance of visible and near-infrared bands at the same time, which has limitations in reducing indoor heat gain in summer. In addition, the preparation process of existing composite materials is complicated, making it difficult to achieve large-scale production and application.

[0008] Therefore, there is an urgent need to develop a composite thermochromic window that can dynamically regulate visible light and near-infrared light at the same time, has a suitable phase change temperature, and has a simple preparation process to meet the actual needs of building energy conservation. Summary of the invention

[0009] In order to solve the technical defects of windows in building energy conservation under the dual-carbon background and realize dual-band dynamic regulation of the solar spectrum, a composite thermochromic window with dual-band dynamic regulation function is provided.

[0010] The technical problem to be solved by the present invention is that, under the current dual-carbon background, windows play an important role in building energy conservation, but traditional statically controlled windows have defects such as increased glass temperature and increased indoor cooling and heating loads. 2 Thermochromic windows have the defects of low visible light transmittance, high phase change temperature and low solar modulation ability; while hydrogel-based thermochromic windows usually show limited near-infrared modulation ability; existing windows can only regulate a single band and cannot dynamically adjust the transmittance of visible light and near-infrared bands at the same time, which has limitations in reducing indoor heat gain in summer.

[0011] The purpose of the present invention can be achieved by the following technical solutions:

[0012] The present invention provides a composite thermochromic window with a dual-band dynamic regulation function, comprising:

[0013] a first transparent substrate,

[0014] A tungsten-doped vanadium dioxide film is deposited on the upper surface of the first transparent substrate, wherein the phase transition temperature of the tungsten-doped vanadium dioxide film is 25-32° C. and the tungsten-doped vanadium dioxide film has a reversible near-infrared radiation control capability above and below its phase transition temperature.

[0015] The second transparent substrate is disposed below the first transparent substrate.

[0016] A hydrogel layer having temperature-responsive visible light scattering control properties, the hydrogel layer being encapsulated between a first transparent substrate and a second transparent substrate, the hydrogel layer being temperature-sensitive poly(N-isopropylacrylamide), the lower critical phase transition temperature of the hydrogel layer being 32±2°C, and when the temperature is higher than 32°C, the visible light scattering rate is increased from less than 10% to more than 35%;

[0017] When the temperature is below 25°C, the infrared transmittance of the tungsten-doped vanadium dioxide film is ≥75%, and the visible light scattering rate of the hydrogel layer is ≤10%.

[0018] When the temperature is higher than 32° C., the near-infrared transmittance of the tungsten-doped vanadium dioxide film is further reduced to a minimum value, and at the same time, the visible light scattering rate of the hydrogel layer is increased to more than 35%.

[0019] Furthermore, the tungsten doping ratio of the tungsten-doped vanadium dioxide film is 2 wt %. The tungsten-doped vanadium dioxide film is prepared on the surface of the first transparent substrate by spin coating, and the film thickness is 60-100 nanometers.

[0020] Furthermore, the thickness of the hydrogel layer is 6 mm.

[0021] Furthermore, the preparation method of the hydrogel layer comprises:

[0022] 1.5 g of N-isopropyl acrylamide monomer, 0.025 g of cross-linking agent N,N'-methylenebisacrylamide and a pre-cooled aqueous solution containing 10 wt% of ammonium persulfate, wherein the temperature of the pre-cooled aqueous solution is 0-4°C, and after mixing, injected into the interlayer between the first transparent substrate and the second transparent substrate to form a hydrogel layer with a cross-linked network structure through a polymerization reaction.

[0023] Furthermore, when the polymerization reaction starts, ultraviolet light with a wavelength of 365 nm is irradiated for 20±2 minutes to initiate the polymerization reaction to form a hydrogel layer with a cross-linked network structure.

[0024] Furthermore, based on the total mass of the hydrogel layer, the mass fraction of the N-isopropylacrylamide monomer in the hydrogel layer is 7.5%, and the added amount of the crosslinking agent N,N'-methylenebisacrylamide is 1.67% of the mass of the monomer.

[0025] Furthermore, the first transparent substrate and the second transparent substrate are both made of quartz glass with a thickness of 1 mm.

[0026] Furthermore, the first transparent substrate and the second transparent substrate are packaged by a hollow acrylic frame to form a sandwich structure.

[0027] Furthermore, the spin coating method adopts a two-step speed control, first depositing at a speed of 500r / s for 12 seconds, and then thinning at a speed of 3000r / s for 60 seconds. The formula of the spin coating colloid contains tungsten-doped VO2 in a mass ratio of 7:7:9:30. 2 , PVB, sodium dodecyl sulfate, water.

[0028] Furthermore, during the preparation of the hydrogel, a pre-cooling treatment is performed for 20-30 minutes, and the UV curing time is controlled at 20±2 minutes.

[0029] The beneficial effects of the present invention are:

[0030] 1. The present invention couples vanadium dioxide and hydrogel to form a multilayer structure, and utilizes the regulation ability of vanadium dioxide in the near-infrared and the regulation ability of hydrogel in the visible light band to achieve dual-band dynamic regulation of the solar spectrum. In summer, when the outdoor temperature is high, vanadium dioxide undergoes a phase change, and has high reflectivity and low transmittance to the near-infrared; the hydrogel reduces the transmittance of visible light, thereby reducing the indoor cold load and achieving the radiation cooling function. In winter, when the outdoor temperature is low, vanadium dioxide does not undergo a phase change, and has a high transmittance to the near-infrared; the transmittance of the hydrogel to visible light is improved, reducing the indoor heat load and achieving the radiation heat collection function.

[0031] 2. The present invention uses VO doped with 2wt% tungsten (W) 2 Thermochromic windows are prepared to reduce the phase transition temperature to about 25°C, which is more suitable for practical application environments. Experimental data show that at a high temperature of 45°C, the transmittance of visible light is 0.67, and the transmittance of near-infrared is 0.68; at a low temperature of 15°C, the transmittance of visible light is 0.78, and the transmittance of near-infrared is 0.77. There is an obvious spectral regulation effect before and after the phase transition.

[0032] 3. Compared with the traditional single near-infrared band control technology, the present invention can further reduce indoor heat gain in summer and increase indoor solar heat gain in winter, thereby reducing the energy consumption of the building's air-conditioning system and maximizing the satisfaction of the building's winter and summer thermal management needs.

[0033] 4. The present invention provides a solution that combines dual - band radiation regulation with temperature - response performance to facilitate passive cooling / heating regulation of indoor temperature, which is of extremely important significance in the field of building energy conservation and emission reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a schematic structural diagram of a composite thermochromic window with dual - band dynamic regulation function in the present invention;

[0035] In the figure: tungsten - doped vanadium dioxide thin film - 1, first transparent substrate - 2, hydrogel layer - 3, second transparent substrate - 4.

[0036] Figure 2 It is a schematic diagram of the summer operation of a composite thermochromic window with dual - band dynamic regulation function in the present invention;

[0037] Figure 3 It is a schematic diagram of the winter operation of a composite thermochromic window with dual - band dynamic regulation function in the present invention;

[0038] Figure 4 It is a spectrogram of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0039] Overall, the present invention discloses a thermochromic window of vanadium dioxide - coupled hydrogel. In view of the important role of windows in building energy conservation under the current dual - carbon background, and considering the many defects of traditional static - regulation windows, such as the increase in the temperature of the glass itself and the increase in indoor cooling and heating loads, the present invention couples and regulates vanadium dioxide and hydrogel, and uses the thermochromic principle to comprehensively regulate visible light and near - infrared. In summer, when the outdoor temperature is high, vanadium dioxide undergoes a phase change, having a high reflectivity and low transmittance to near - infrared; the hydrogel reduces the transmittance of visible light, thereby reducing the indoor cooling load and realizing the radiation cooling function; in winter, when the outdoor temperature is low, vanadium dioxide does not undergo a phase change and has a relatively high transmittance to near - infrared; the transmittance of the hydrogel to visible light increases, reducing the indoor heating load and realizing the radiation heat - collection function. The present invention provides a solution that combines dual - band radiation regulation with temperature - response performance to facilitate passive cooling / heating regulation of indoor temperature, which is of extremely important significance in the field of building energy conservation and emission reduction.

[0040] The present invention includes a vanadium dioxide thin film covering quartz glass as the outermost layer, a hydrogel as the middle interlayer, and ordinary quartz glass as the innermost layer. Based on the design and controllable preparation of cold / heat - control materials, the microstructure of the hydrogel is regulated, the regulation behavior of the dual - temperature - control window material for building thermal management is verified and evaluated, and the dual - band temperature - control performance of the material and the building energy - saving benefit are optimized.

[0041] Vanadium dioxide is a typical thermochromic material. When the temperature is lower than the phase transition temperature, the transmittance of vanadium dioxide to near-infrared light is high, and heat can enter the room through the window; when the temperature is higher than the phase transition temperature, the transmittance of vanadium dioxide to infrared light is significantly reduced, while the transmittance to visible light remains unchanged, so the heat generated by infrared light cannot enter the room, achieving the effect of blocking heat exchange through the window. And this change is reversible, which can well adapt to the temperature changes in the morning and evening and the four seasons in real life.

[0042] Thermochromic hydrogel is an organic polymer material with unique optical properties. Its working principle can be summarized as the optical property of reversible conversion between transparent and opaque with temperature changes. This property makes thermochromic hydrogel an ideal phase change material for preparing windows.

[0043] The present invention uses VO doped with 2wt% tungsten (W) 2 Thermochromic windows are prepared to reduce the phase transition temperature to about 25°C, which is more in line with the actual application requirements of the building environment. 2 Coupled with hydrogel to prepare a multilayer structure, using VO 2 The regulation capability in near infrared and the regulation capability of hydrogel in visible light band can realize dual-band dynamic regulation of solar spectrum. Compared with the traditional single near infrared band regulation technology, the present invention can further reduce indoor heat gain in summer and increase indoor solar heat gain in winter, thereby reducing the energy consumption of building air conditioning system and maximizing the demand for building heat management in winter and summer.

[0044] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. Any features such as preparation means, materials, structures or composition ratios not clearly described in this technical solution are regarded as common technical features disclosed in the prior art.

[0045] Example 1

[0046] See also Figure 1The composite thermochromic window with dual-band dynamic regulation function in the present invention comprises a first transparent substrate 2, a tungsten-doped vanadium dioxide film 1, a hydrogel layer 3, and a second transparent substrate 4, wherein: the tungsten-doped vanadium dioxide film 1 is deposited on the upper surface of the first transparent substrate 2, the phase transition temperature of the tungsten-doped vanadium dioxide film 1 is 25-32°C, and the tungsten-doped vanadium dioxide film 1 has a reversible near-infrared radiation regulation capability above and below its phase transition temperature, the second transparent substrate 4 is arranged below the first transparent substrate 2, the hydrogel layer 3 has a temperature-responsive visible light scattering regulation characteristic, and the hydrogel layer 3 is encapsulated on the first transparent substrate 2 Between the second transparent substrate 4, the hydrogel layer 3 is a temperature-sensitive poly (N-isopropylacrylamide), and the lower critical phase transition temperature of the hydrogel layer 3 is 32±2°C. When the temperature is higher than 32°C, the visible light scattering rate is increased from less than 10% to more than 35%; when the temperature is below 25°C, the infrared transmittance of the tungsten-doped vanadium dioxide film 1 is ≥75%, and the visible light scattering rate of the hydrogel layer 3 is ≤10%. When the temperature is higher than 32°C, the near-infrared transmittance of the tungsten-doped vanadium dioxide film 1 is further reduced to the minimum value, and at the same time, the visible light scattering rate of the hydrogel layer 3 is increased to more than 35%.

[0047] Specifically, during preparation, a vanadium dioxide film is deposited by spin coating. Because vanadium dioxide is insoluble in water, vanadium dioxide colloid is prepared, and vanadium dioxide (2wt% tungsten), thickener (polyvinylidene PVB), dispersant (sodium dodecyl sulfate), and water are mixed in a mass ratio of 7:7:9:30, and stirred on a magnetic stirrer for 24-48 hours. The experimental parameters are 20°C and 900r / min. After the vanadium dioxide colloid is prepared, it is spin-coated on a homogenizer. First, rotate at a low speed of 500r / s for 12s to evenly deposit the vanadium dioxide colloid on the glass sheet, and then rotate at a high speed of 3000r / s for 60s to thin it. After the suspension coating is completed, place the glass sheet in a vacuum dryer for drying.

[0048] In the process of preparing the hydrogel, first, 1.5 g of N-isopropylacrylamide was added to 20 ml of deionized water to form a 7.5% N-isopropylacrylamide solution. Then, 0.025 g of N, N'-methylenebisacrylamide was added and placed on a magnetic stirrer for mixing. Next, a starter was prepared by adding 0.1 g of ammonium persulfate to deionized water and configuring a 10% mass fraction solution. At the same time, a catalyst was prepared by weighing 0.1 g of N, N, N', N'tetramethylethylenediamine solution using a rubber-tipped dropper, and adding deionized water to 1 g to configure a 10% mass fraction solution.

[0049] In the pre-cooling step, the prepared mixed solution, starter, catalyst, etc. are wrapped with plastic wrap and placed on the upper layer of the refrigerator for pre-cooling for 20-30 minutes. In the mixing step, 10 microliters of ammonium persulfate solution and 50 microliters of N, N, N', N'tetramethylethylenediamine solution are measured with a pipette and added to the mixed solution, and slightly stirred. Finally, the mixed solution is irradiated under ultraviolet light for 20 minutes to solidify the mixed solution to form a hydrogel.

[0050] Finally, the prepared hydrogel and vanadium dioxide film glass sheets were packaged and connected by a hollow acrylic frame and spin-coated with VO 2 The glass sheet of the film is the outermost layer, the middle layer is injected with hydrogel, and the innermost layer is ordinary glass. The encapsulated glass is installed in the model house to make windows.

[0051] like Figure 2 As shown, in summer, when the outdoor temperature is high, the window undergoes a phase change, having high reflectivity and low transmittance for near-infrared and low transmittance for visible light, thereby reducing the indoor cooling load.

[0052] like Figure 3 As shown, in winter, the outdoor temperature is low and the window does not undergo phase change, the reflectivity to near-infrared decreases, the transmittance increases, and the transmittance to visible light increases, reducing the indoor heat load.

[0053] The glass window of the present invention is made of vanadium dioxide and hydrogel composite material, and realizes the function of radiation cooling in summer and radiation heat collection in winter through the thermochromic principle.

[0054] like Figure 4 As shown, when the window is at a high temperature of 45°C, the transmittance of visible light is 0.67, and the transmittance of near-infrared is 0.68; when it is at a low temperature of 15°C, the transmittance of visible light is 0.78, and the transmittance of near-infrared is 0.77. It has an obvious spectral regulation effect before and after the phase change.

[0055] This window is designed with economy, environmental protection and energy saving as its design concept. It uses the thermochromic principle and adopts vanadium dioxide and hydrogel composite materials to achieve coordinated regulation of visible light and near-infrared, and maximize the adaptation to the needs of dynamic thermal management of buildings in winter and summer. In summer, the window reduces the indoor cold load and realizes the radiation cooling function; in winter, the window reduces the indoor heat load and realizes the radiation heat collection function. The present invention provides a solution for passive cooling / heating regulation of indoor temperature by coordinated regulation of visible light and near-infrared, which is in line with the low-carbon development of my country's construction field, especially green buildings, and has significant environmental protection significance in the field of building energy conservation and emission reduction.

[0056] Example 2

[0057] A composite thermochromic window with dual-band dynamic regulation function comprises a first transparent substrate, a tungsten-doped vanadium dioxide film, a second transparent substrate and a hydrogel layer.

[0058] The first transparent substrate is a quartz glass with a thickness of 1 mm, and a tungsten-doped vanadium dioxide film is deposited on the upper surface of the first transparent substrate. The tungsten doping ratio of the tungsten-doped vanadium dioxide film is 2wt%, and the phase transition temperature is 25°C. It has a reversible near-infrared radiation regulation capability above and below its phase transition temperature. When the temperature is below 25°C, the infrared transmittance of the tungsten-doped vanadium dioxide film is 78%; when the temperature is higher than 32°C, the near-infrared transmittance of the tungsten-doped vanadium dioxide film is further reduced to a minimum value of about 28%.

[0059] The second transparent substrate is arranged below the first transparent substrate and is also made of quartz glass with a thickness of 1 mm. The first transparent substrate and the second transparent substrate are encapsulated by a hollow acrylic frame to form a sandwich structure. The thickness of the frame is 6 mm, which matches the thickness of the hydrogel layer.

[0060] The hydrogel layer is encapsulated between the first transparent substrate and the second transparent substrate, and has temperature-responsive visible light scattering control properties. The hydrogel layer is a temperature-sensitive poly (N-isopropylacrylamide), and its lower critical phase transition temperature is 32±2°C. When the temperature is below 30°C, the visible light scattering rate of the hydrogel layer is 8%; when the temperature is above 32°C, the visible light scattering rate of the hydrogel layer increases to 38%.

[0061] The tungsten-doped vanadium dioxide film was prepared on the surface of the first transparent substrate by spin coating, and the film thickness was 60 nanometers. The spin coating method adopted a two-step speed control, first depositing at 500 rpm for 12 seconds, and then thinning at 3000 rpm for 60 seconds. The formula of the spin coating colloid contains tungsten-doped VO2 in a mass ratio of 7:7:9:30. 2 , PVB, sodium dodecyl sulfate, water.

[0062] The preparation method of the hydrogel layer includes: mixing 1.5g of N-isopropylacrylamide monomer, 0.025g of cross-linking agent N,N'-methylenebisacrylamide and a pre-cooled aqueous solution containing 10wt% ammonium persulfate, the temperature of the pre-cooled aqueous solution is 0°C, and the mixture is pre-cooled in an ice bath for 20 minutes. After mixing, the solution is injected into the interlayer between the first transparent substrate and the second transparent substrate to form a hydrogel layer with a cross-linked network structure through a polymerization reaction. At the beginning of the polymerization reaction, ultraviolet light with a wavelength of 365nm is irradiated for 18 minutes to initiate a polymerization reaction to form a hydrogel layer with a cross-linked network structure. Based on the total mass of the hydrogel layer, the mass fraction of N-isopropylacrylamide monomer in the hydrogel layer is 7.5%, and the amount of cross-linking agent N,N'-methylenebisacrylamide added is 1.67% of the monomer mass.

[0063] The working principle of the composite thermochromic window is similar to that of Example 1, but due to the thin thickness of the tungsten-doped vanadium dioxide film (60 nanometers), its near-infrared transmittance at low temperatures is higher (78%), while the near-infrared blocking effect at high temperatures is slightly reduced. At the same time, the visible light scattering rate of the hydrogel layer at low temperatures is slightly lower (8%), which makes the window have better light transmission performance in winter.

[0064] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A composite thermochromic window with dual-band dynamic regulation function, characterized in that: include: a first transparent substrate (2), A tungsten-doped vanadium dioxide film (1) is deposited on the upper surface of the first transparent substrate (2), the phase transition temperature of the tungsten-doped vanadium dioxide film (1) is 25-32° C., and the tungsten-doped vanadium dioxide film (1) has a reversible near-infrared radiation control capability above and below its phase transition temperature. The second transparent substrate (4) is arranged below the first transparent substrate (2). A hydrogel layer (3) having temperature-responsive visible light scattering control properties, the hydrogel layer (3) being encapsulated between a first transparent substrate (2) and a second transparent substrate (4), the hydrogel layer (3) being temperature-sensitive poly(N-isopropylacrylamide), the lower critical phase transition temperature of the hydrogel layer (3) being 32±2°C, and when the temperature is higher than 32°C, the visible light scattering rate is increased from less than 10% to more than 35%; When the temperature is below 25° C., the infrared transmittance of the tungsten-doped vanadium dioxide film (1) is ≥75%, and the visible light scattering rate of the hydrogel layer (3) is ≤10%. When the temperature is higher than 32° C., the near-infrared transmittance of the tungsten-doped vanadium dioxide film (1) is further reduced to a minimum value, while the visible light scattering rate of the hydrogel layer (3) is increased to more than 35%.

2. The composite thermochromic window with dual-band dynamic regulation function according to claim 1, characterized in that: The tungsten doping ratio of the tungsten-doped vanadium dioxide film (1) is 2 wt %. The tungsten-doped vanadium dioxide film (1) is prepared on the surface of the first transparent substrate (2) by spin coating, and the film thickness is 60-100 nanometers.

3. The composite thermochromic window with dual-band dynamic regulation function according to claim 1, characterized in that: The thickness of the hydrogel layer (3) is 6 mm.

4. The composite thermochromic window with dual-band dynamic regulation function according to claim 1, characterized in that: The preparation method of the hydrogel layer (3) comprises: 1.5 g of N-isopropyl acrylamide monomer, 0.025 g of cross-linking agent N,N'-methylenebisacrylamide and a pre-cooled aqueous solution containing 10 wt% of ammonium persulfate, wherein the temperature of the pre-cooled aqueous solution is 0-4° C., and after mixing, the pre-cooled aqueous solution is injected into the interlayer between the first transparent substrate (2) and the second transparent substrate (4), and a hydrogel layer (3) with a cross-linked network structure is formed through a polymerization reaction.

5. The composite thermochromic window with dual-band dynamic regulation function according to claim 4, characterized in that: When the polymerization reaction begins, ultraviolet light with a wavelength of 365 nm is irradiated for 20±2 minutes to initiate the polymerization reaction to form a hydrogel layer (3) with a cross-linked network structure.

6. The composite thermochromic window with dual-band dynamic regulation function according to claim 1, characterized in that: Based on the total mass of the hydrogel layer, the mass fraction of the N-isopropylacrylamide monomer in the hydrogel layer (3) is 7.5%, and the added amount of the crosslinking agent N,N'-methylenebisacrylamide is 1.67% of the mass of the monomer.

7. The composite thermochromic window with dual-band dynamic regulation function according to claim 1, characterized in that: The first transparent substrate (2) and the second transparent substrate (4) are both made of quartz glass with a thickness of 1 mm.

8. The composite thermochromic window with dual-band dynamic regulation function according to claim 1, characterized in that: The first transparent substrate (2) and the second transparent substrate (4) are packaged by a hollow acrylic frame to form a sandwich structure.

9. The composite thermochromic window with dual-band dynamic regulation function according to claim 2, characterized in that: The spin coating method adopts two-step speed control, first depositing at a speed of 500r / s for 12 seconds, and then thinning at a speed of 3000r / s for 60 seconds. The formula of the spin coating colloid contains tungsten-doped VO2, PVB, sodium dodecyl sulfate, and water in a mass ratio of 7:7:9:

30.

10. The composite thermochromic window with dual-band dynamic regulation function according to claim 1, characterized in that: During the preparation of the hydrogel, a pre-cooling treatment is performed for 20-30 minutes, and the UV curing time is controlled within 20±2 minutes.

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