Solar photo-thermal temperature control film and preparation method thereof

Abstract

The invention relates to the technical field of films, and particularly discloses a solar photo-thermal temperature control film and a preparation method thereof. The surface of the solar photo-thermal temperature control film comprises a microstructure; the microstructure comprises a vertical surface and a slope surface. According to the thin film, the microstructure is formed on the surface of the thin film through the imprinting technology, and the microstructure can regulate and control the propagation path of light. The microstructures automatically adjust absorption and reflection characteristics according to incident angle changes of sunlight, the film can provide more comfortable indoor environment temperature, and dependence on an artificial heating and cooling system is reduced. The optical characteristics of the thin film can be dynamically adjusted, so that the energy management of the thin film can be optimized under different illumination conditions all the year round. The energy utilization efficiency is obviously improved and the energy consumption is reduced. And the film reduces the carbon emission of the building by reducing the energy requirements of heating and refrigeration, and has remarkable environmental protection benefits.

Description

Technical Field

[0001] The present invention relates to the field of thin film technology, and in particular to a solar thermal temperature control thin film and a preparation method thereof. Background Art

[0002] In the current global context of increasing awareness of energy conservation and environmental protection, efficient use of solar energy has become a key goal for all industries. As a clean energy, the effective use of solar energy can not only reduce dependence on fossil fuels, but also reduce greenhouse gas emissions, thereby slowing down the pace of global warming. Optimizing the efficiency of solar energy use will help improve overall energy utilization, while promoting environmental protection and achieving sustainable development goals.

[0003] The optical properties of the surface materials of traditional outdoor structures are static, which means that they cannot automatically adjust the absorption and reflection of light according to environmental changes. The performance and efficiency of these materials are limited under different lighting conditions. For example, white outdoor surfaces with high reflectivity can strongly reflect sunlight. This high reflectivity helps reduce the absorbed heat in the summer, thereby reducing cooling energy consumption. However, in the winter, the same highly reflective materials cannot effectively absorb solar heat, resulting in more energy required for heating. Therefore, these materials have limitations in coping with different seasons and temperature changes and cannot provide optimized thermal energy management throughout the year.

[0004] Therefore, it is necessary to provide a solar thermal temperature control film and a preparation method thereof to significantly improve energy utilization efficiency and reduce energy consumption. Summary of the invention

[0005] The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art. To this end, the present invention proposes a solar thermal temperature control film and a preparation method thereof, which can significantly improve the energy utilization efficiency and reduce energy consumption.

[0006] The inventive concept of the present invention is to design microstructures to respond to the changing laws of sunlight, so that the film can automatically adjust the absorption and reflection characteristics of the material under different lighting conditions. In winter when the incident angle of sunlight is low, the microstructure can increase the absorption of sunlight to improve heat gain; in summer or when the sun is directly shining, the microstructure on the film can increase the reflectivity and reduce heat absorption, thereby lowering the indoor temperature.

[0007] A first aspect of the present invention provides a solar thermal temperature control film.

[0008] Specifically, the surface of the solar thermal temperature control film includes a microstructure;

[0009] The microstructure includes a vertical surface and a slope surface.

[0010] Preferably, the height of the vertical surface is 0.1 - 1 cm.

[0011] More preferably, the height of the vertical surface is 0.1 - 0.5 cm.

[0012] Even more preferably, the height of the vertical surface is 0.1 cm.

[0013] Preferably, the inclination angle of the slope surface is 20 - 30 degrees.

[0014] More preferably, the inclination angle of the slope surface is 20 - 25 degrees.

[0015] Even more preferably, the inclination angle of the slope surface is 22 degrees.

[0016] Preferably, the structural parameters of the micro-structure satisfy A < arctan(h / t) < 90 - 2*x;

[0017] wherein, A is the maximum incident angle of winter light, h is the height of the vertical surface, t is the distribution distance between the vertical surface and the slope surface, and x is the inclination angle of the slope surface.

[0018] When the distribution distance (t) between the vertical surface and the slope surface is too large, that is, arctan(h / t) < A, the part of the winter light incident angle greater than arctan(h / t) will not be able to pass through the film, that is, the effect of absorbing radiation in winter is reduced.

[0019] When the inclination angle (x) of the slope surface is too large, the part of the summer light incident on the slope surface is reflected and further passes through the transparent vertical surface and through the film, that is, the effect of reducing the absorption of radiation in summer is reduced.

[0020] Preferably, the distribution distance (t) between the vertical surface and the slope surface is 0.1 - 1 cm.

[0021] Preferably, the surface of the slope surface is covered with a high-reflection layer.

[0022] Preferably, the material of the high-reflection layer includes any one of aluminum and silver.

[0023] Preferably, the thickness of the high-reflection layer is 50 - 1000 nm.

[0024] More preferably, when the material of the high-reflection layer is aluminum, the thickness of the high-reflection layer is 100 - 1000 nm; when the material of the high-reflection layer is silver, the thickness of the high-reflection layer is 50 - 200 nm.

[0025] Preferably, the reflectivity of the high-reflection layer is 90 - 98%.

[0026] Preferably, the material of the solar thermal temperature control film includes any one of polydimethylsiloxane (PDMS) and polymethyl methacrylate (PMMA).

[0027] Preferably, the thickness of the microstructure is 0.1 to 1 cm.

[0028] A second aspect of the present invention provides a method for preparing a solar thermal temperature control film.

[0029] Specifically, the following steps are included:

[0030] The solar thermal temperature control film is obtained by forming a microstructure on the material of the solar thermal temperature control film using an embossing technique, and then forming a high reflective layer on the surface of the microstructure using an evaporation coating process.

[0031] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0032] The film of the present invention uses an embossing technique to form a microstructure on the film surface, and the microstructure can regulate the propagation path of light. The microstructure automatically adjusts the absorption and reflection characteristics according to the change of the incident angle of sunlight. The film can provide a more comfortable indoor environment temperature and reduce the dependence on artificial heating and cooling systems. Since the optical properties of the film can be dynamically adjusted, the film can optimize energy management under different lighting conditions throughout the year. It significantly improves energy utilization efficiency and reduces energy consumption. The film reduces the carbon emissions of buildings by reducing the energy demand for heating and cooling, and has significant environmental benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a schematic diagram of the structure of the solar thermal temperature control film prepared in Example 1 of the present invention;

[0034] Figure 2 The transmittance and incident angle variation curve of the solar thermal temperature control film prepared in Example 1 of the present invention;

[0035] Figure 3 This is a temperature control effect diagram of the solar thermal temperature control film prepared in Example 1 of the present invention under high angle incidence;

[0036] Figure 4 This is a diagram showing the temperature control effect of the solar thermal temperature control film prepared in Example 1 of the present invention at a low incident angle. DETAILED DESCRIPTION

[0037] In order to make the technical scheme of the present invention more clearly understood by those skilled in the art, the following embodiments are listed for illustration. It should be pointed out that the following embodiments do not limit the protection scope of the present invention.

[0038] Unless otherwise specified, the raw materials, reagents or devices used in the following examples can be obtained from conventional commercial sources or by existing known methods.

[0039] Example 1

[0040] A solar thermal temperature control film and a preparation method thereof.

[0041] Solar thermal temperature control film: PDMS material is used to emboss a PDMS film with a microstructure. The height of the vertical surface is 0.1 cm, the inclination angle of the slope surface is 22 degrees, and the distribution spacing between the vertical surface and the slope surface is 0.1 cm. The surface of the slope surface is covered with an Al high reflective layer with a thickness of 100 nm and a reflectivity of 92%.

[0042] Preparation method: The embossing technology is used to form a microstructure on the material of the solar thermal temperature control film, and then the evaporation coating process is used to coat aluminum on the surface of the microstructure to form a high reflective layer. During the coating process, the microstructure film needs to be appropriately tilted to ensure that a high reflective material film is coated on the slope surface to obtain the solar thermal temperature control film.

[0043] Figure 1 Schematic diagram of the structure of the solar thermal temperature control film prepared in Example 1 of the present invention, as shown in Figure 1 As shown, the film as a whole is composed of a highly reflective sloping surface and a highly transmissive vertical surface. When the angle between the incident light 1 and the bottom surface of the film is lower than 43 degrees, the light can pass through the vertical surface through the film due to the low angle, and reach the space below the film as shown by light 3; when the angle between the incident light 2 and the bottom surface of the film is higher than 90 degrees, the light is completely reflected by the highly reflective sloping surface; when the angle between the incident light and the bottom surface of the film is between 43 and 90 degrees, the transmittance of the film decreases as the angle increases.

[0044] Figure 2 The transmittance and incident angle curve of the solar thermal temperature control film prepared in Example 1 of the present invention is shown in FIG. 1 , where the slope angle of the slope surface of the film is 22 degrees. Ray tracing is used to simulate incident light at different angles passing through the film, and the transmittance of the film at different angles is arranged and plotted as shown in FIG. Figure 2 As shown, from the relationship between the incident angle and the transmittance of the film, it can be seen that when the inclination angle of the slope surface of the film is 22 degrees, the incident light below 43 degrees can all pass through the film and the transmittance is 1. The transmittance of the incident light above 43 degrees gradually decreases with the increase of the angle. When the incident angle reaches 90 degrees, all the light is reflected, so the transmittance of the film is 0.

[0045] Figure 3The temperature control effect of the solar thermal temperature control film prepared in Example 1 of the present invention under high angle incidence is shown in Figure 1. Taking the sunlight incident on the summer solstice in Dongguan as an example, the sunlight at noon in Dongguan on the summer solstice is almost vertically incident on the bottom surface, that is, the incident angle is close to 90 degrees. Figure 3 As shown, the absorption rate of the heat absorbing material is 0.9 and the emissivity is 0.8; the absorption rate of the cooling material is 0.1 and the emissivity is 0.1. Due to the high absorption rate of the heat absorbing material, the temperature presented can reach up to 80°C. The cooling material has a low absorption rate and small temperature fluctuations, and the average temperature is close to the outdoor temperature of 35°C.

[0046] Compared with the heat-absorbing materials and refrigeration materials in the same environment, the solar thermal temperature control film prepared in Example 1 of the present invention has a transmittance of 0 for light incident at high angles, but there is still some scattered light in the actual sunlight. This part of the scattered light can pass through the film through the vertical surface, and a small amount of light is transmitted through the entire film. A material with an absorption rate of 0.9 is placed under the film and its temperature is detected. The detection shows that the temperature under the film fluctuates little and the overall temperature is about 40°C lower than that of the heat-absorbing material without film coverage. That is, the solar thermal temperature control film prepared in Example 1 of the present invention can better block the incidence of high-angle light, so that the material covered with the film can still maintain a low temperature in the summer with high-angle incidence.

[0047] Figure 4 This is a temperature control effect diagram of the solar thermal temperature control film prepared in Example 1 of the present invention at a low incident angle. Taking the incident sunlight in Shanghai on the winter solstice as an example, the incident angle of sunlight at noon in Shanghai on the winter solstice is 32 degrees, that is, the sunlight in Shanghai on the winter solstice can all pass through the film. The temperature curves of the heat-absorbing material, the refrigeration material and the solar thermal temperature control film were simulated using the actual environmental data of Shanghai in winter.

[0048] Compared with heat-absorbing materials and refrigeration materials in the same environment, the solar thermal temperature-control film prepared in Example 1 of the present invention is in a transmissive state for light with low incident angles. A material with an absorption rate of 0.9 is placed under the film and its temperature is detected. The detection shows that the overall temperature under the film is about 20°C higher than that of the refrigeration material with low absorption rate. That is, the solar thermal temperature-control film prepared in Example 1 of the present invention can transmit most of the light at low incident angles, so that the material covering the film can still maintain a relatively high temperature in winter at low angles.

[0049] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution obtained by any modification, equivalent replacement, improvement, etc. made by a person skilled in the art based on the concept of the present invention through logical analysis, reasoning or limited experiments on the basis of the prior art shall be within the scope of protection determined by the claims.

Claims

1. A solar thermal temperature control film, characterized in that: The surface of the solar thermal temperature control film includes a microstructure; The microstructure includes a vertical surface and a slope surface.

2. The solar thermal temperature control film according to claim 1, characterized in that: The height of the vertical surface is 0.1-1 cm.

3. The solar thermal temperature control film according to claim 1, characterized in that: The inclination angle of the slope surface is 20 to 30 degrees.

4. The solar thermal temperature control film according to claim 1, characterized in that: The structural parameters of the microstructure satisfy A <arctan(h / t)<90-2*x; Among them, A is the maximum incident angle of light in winter, h is the height of the vertical surface, t is the distribution distance between the vertical surface and the slope surface, and x is the inclination angle of the slope surface.

5. The solar thermal temperature control film according to claim 1, characterized in that: The surface of the slope surface is covered with a high reflection layer.

6. The solar thermal temperature control film according to claim 5, characterized in that: The material of the high reflective layer includes any one of aluminum and silver.

7. The solar thermal temperature control film according to claim 5, characterized in that: The thickness of the high reflection layer is 50-1000 nm.

8. The solar thermal temperature control film according to claim 5, characterized in that: The reflectivity of the high reflective layer is 90-98%.

9. The solar thermal temperature control film according to claim 1, characterized in that: The material of the solar thermal temperature control film includes any one of polydimethylsiloxane and polymethyl methacrylate.

10. The method for preparing the solar thermal temperature control film according to any one of claims 1 to 9, characterized in that: The following steps are involved: The solar thermal temperature control film is obtained by forming a microstructure on the material of the solar thermal temperature control film using an embossing technique, and then forming a high reflective layer on the slope surface using an evaporation coating process.

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