Phase-change cooling coating, preparation method thereof, phase-change cooling coating, composite cooling coating and application of phase-change cooling coating to surface of photovoltaic module

Abstract

The invention provides a phase-change cooling coating, a preparation method thereof, a phase-change cooling coating, a composite cooling coating and application of the composite cooling coating to the surface of a photovoltaic module, and relates to the technical field of photovoltaic cooling coatings. The preparation method of the phase-change cooling coating provided by the invention comprises the following steps: stirring and dissolving a polyvinylidene fluoride-hexafluoropropylene copolymer in a polar aprotic solvent to prepare a precursor solution; adding acrylic resin into the precursor solution, stirring and dispersing to obtain a precursor coating; adding a phase-change material, hydrophobic silicon dioxide nanoparticles and graphene into the precursor coating, and stirring and dispersing to obtain a composite phase-change coating; the phase change material comprises n-tetradecanol, n-octadecanol or polyethylene glycol. According to the radiation phase change cooling coating prepared by the invention, heat accumulation in the module can be reduced through heat storage and release of the phase change material and timely heat dissipation of the radiation material, the cooling effect on the photovoltaic module is further enhanced, and efficient and stable operation of the photovoltaic module is guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic cooling coatings, and in particular to a phase change cooling coating and a preparation method thereof, a phase change cooling coating, a composite cooling coating and their application on the surface of a photovoltaic module. Background Art

[0002] As the application scale of solar photovoltaic power generation systems continues to expand, photovoltaic power generation will become the world's most important energy producer. However, in actual applications, photovoltaic power generation systems are generally under high solar radiation, and the operating temperature of photovoltaic power generation systems has an important impact on their efficiency and durability. Studies have shown that for every 1°C increase in the operating temperature of crystalline silicon photovoltaic modules, their output power decreases by 0.35%-0.5%, and after exceeding their upper limit temperature, their service life is shortened by half for every 10°C increase in working temperature. Therefore, it is particularly important to efficiently dissipate heat and cool photovoltaic modules.

[0003] In the prior art, there are two types of cooling technologies for photovoltaic modules: active and passive. Active cooling mainly includes medium cooling, which uses fluid media such as air and liquid to exchange heat on the surface of photovoltaic modules to remove excess heat. It has a good cooling effect, but this active method often requires energy input, which will reduce the net energy efficiency of the photovoltaic system. At the same time, this cooling system is relatively complex, and the installation and maintenance costs are high, which further increases the overall cost of the photovoltaic system. Passive cooling methods mainly include phase change cooling, hygroscopic cooling and radiation cooling. The former two mainly use heat storage materials to absorb the heat of photovoltaic modules during the day and release the heat to the environment at night. Radiation cooling is to exchange heat with the environment and outer space through wide-band thermal radiation. However, how to improve the cooling efficiency of photovoltaic modules to improve the net efficiency of photovoltaic modules, increase output power and extend service life is still a problem that needs to be solved urgently. Summary of the invention

[0004] The purpose of the present invention is to provide a phase change cooling paint and a preparation method thereof, a phase change cooling coating, a composite cooling coating and their application on the surface of a photovoltaic module.

[0005] In the first aspect, the present invention provides a method for preparing a phase change cooling coating, comprising: stirring and dissolving a polyvinylidene fluoride-hexafluoropropylene copolymer in a polar aprotic solvent to obtain a precursor solution; adding an acrylic resin to the precursor solution and stirring and dispersing it to obtain a precursor coating; adding a phase change material, hydrophobic silica nanoparticles and graphene to the precursor coating and stirring and dispersing it to obtain a composite phase change coating; the phase change material comprises n-tetradecanol, n-octadecyl alcohol or polyethylene glycol.

[0006] Optionally, when adding an acrylic resin to the precursor solution and stirring for dispersion, the mass percentage of the polyvinylidene fluoride-hexafluoropropylene copolymer in the mixture formed by the acrylic resin and the polyvinylidene fluoride-hexafluoropropylene copolymer is 60%-80%.

[0007] Optionally, the polar aprotic solvent is N,N-dimethylformamide, N,N-dimethylacetamide, or N-methylpyrrolidone.

[0008] Optionally, the particle size of the hydrophobic silica nanoparticles is 7nm-20nm.

[0009] Optionally, the mass ratio of graphene to the polyvinylidene fluoride-hexafluoropropylene copolymer is 0.5-2.0%.

[0010] In a second aspect, the present invention provides a phase change cooling coating prepared by any of the above optional preparation methods.

[0011] In a third aspect, the present invention provides a phase change cooling coating prepared by any of the above optional preparation methods or a phase change cooling coating formed after curing the phase change cooling coating provided in the second aspect.

[0012] In a fourth aspect, the present invention provides a composite phase change coating having at least one layer of the phase change cooling coating provided in the third aspect.

[0013] Optionally, it includes a phase change cooling coating and a radiative cooling coating that are superposed on each other, and the composite cooling coating is formed by curing a radiative cooling coating.

[0014] Optionally, the preparation method of the radiative cooling coating includes: adding modified alumina and graphene to a precursor coating and stirring for dispersion to obtain a radiative cooling coating; wherein, the modified alumina is spherical alumina surface-modified with siloxane.

[0015] Optionally, the preparation method of the modified alumina includes the following steps: immersing spherical alumina in a modification solution dissolved with a siloxane surface modifier, stirring for dispersion, and then filtering and drying to obtain modified alumina; wherein, the siloxane surface modifier includes at least one of γ-aminopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, and γ-aminopropyltriethoxysilane.

[0016] In a fifth aspect, the present invention further provides an application of any of the above optional phase change cooling coatings, phase change cooling coatings, or composite phase change coatings on the surface of a photovoltaic module.

[0017] Optionally, at least one layer of the phase change cooling coating is cured on the back surface of the photovoltaic module. Description of the Drawings

[0018] Figure 1Flow chart of a preparation method of a phase change cooling coating provided by the present invention;

[0019] Figure 2 Infrared emissivity spectrum of the radiative cooling coating provided in Application Example 5 of the present invention;

[0020] Figure 3 Comparison chart of the back surface cooling performance of the photovoltaic module in Application Example 1 of the present invention and the photovoltaic module without the coated coating;

[0021] Figure 4 Comparison chart of the output power and photoelectric conversion efficiency of the photovoltaic module in Application Example 1 of the present invention and the photovoltaic module without the coated coating. Detailed implementation manners

[0022] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Apparently, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention. Unless otherwise defined, the technical terms or scientific terms used herein shall have the ordinary meanings as understood by those of ordinary skill in the art belonging to the present invention.

[0023] Refer to Figure 1 , the present invention provides a preparation method of a phase change cooling coating, including:

[0024] S1. Stir and dissolve polyvinylidene fluoride - hexafluoropropylene copolymer (PVDF - HFP) in a polar aprotic solvent to obtain a precursor solution;

[0025] S2. Add an acrylic resin to the precursor solution and stir to disperse to obtain a precursor coating;

[0026] S3. Add a phase change material, hydrophobic silica nanoparticles and graphene to the precursor coating and stir to disperse to obtain a composite phase change coating.

[0027] Actually, when performing step S1, the polar aprotic solvent used includes at least one of N,N - dimethylformamide (DMF), N,N - dimethylacetamide (DMAc), and N - methylpyrrolidone (NMP).

[0028] In some embodiments, when performing step S1, after adding the polyvinylidene fluoride - hexafluoropropylene copolymer to the polar aprotic solvent, magnetic stirring can be carried out in a water bath environment at 40°C - 60°C until the polyvinylidene fluoride - hexafluoropropylene copolymer is completely dissolved, and then the precursor solution is obtained.

[0029] In some embodiments, when performing step S2, the mass percentage of the polyvinylidene fluoride - hexafluoropropylene copolymer in the mixture formed by the acrylic resin and the polyvinylidene fluoride - hexafluoropropylene copolymer is 60% - 80%.

[0030] In some embodiments, when performing step S2, after adding the acrylic resin to the precursor solution, it is stirred under mechanical actions such as magnetic force to prepare a uniform and stable precursor coating, and the precursor coating is a milky viscous liquid.

[0031] In some embodiments, when performing step S3, it includes: adding a phase change material and hydrophobic silica nanoparticles to the precursor coating, stirring and mixing them, then adding graphene, stirring and dispersing, and standing to defoam to obtain a composite phase change coating. Specifically, the phase change materials used include n - tetradecanol, n - octadecanol or polyethylene glycol, and the particle size of the hydrophobic silica nanoparticles is 7nm - 20nm. In addition, the mass ratio of graphene to the polyvinylidene fluoride - hexafluoropropylene copolymer added in step S1 is 0.5 - 20%.

[0032] In fact, the polyvinylidene fluoride - hexafluoropropylene copolymer, acrylic resin, hydrophobic silica nanoparticles and graphene used in any of the above embodiments can all be commercially available conventional products. For example, the polyvinylidene fluoride - hexafluoropropylene copolymer can be a product with the model number 2801 - 01 and a molecular weight of 400000 purchased from Dongguan Zhanyang High - molecular Materials Co., Ltd., and the acrylic resin can be a product with the model number BR - 106 and a molecular weight of 60000 purchased from Mitsubishi Rayon.

[0033] In fact, the present invention also provides a phase - change cooling coating prepared by using any of the above optional embodiments. At the same time, after the phase - change cooling coating is coated into a film and cured, a phase - change cooling coating can be formed, which can absorb heat when the ambient temperature is high and release heat when the ambient temperature is low by using the phase - change materials therein.

[0034] In addition, the present invention also provides a composite phase - change coating, including a phase - change cooling coating and a radiative cooling coating stacked on each other, wherein the radiative cooling coating used is formed by curing a radiative cooling coating. Specifically, the preparation method of the radiative cooling coating used includes: adding modified alumina and graphene to the precursor coating, stirring and dispersing to obtain a radiative cooling coating; wherein, the modified alumina is spherical alumina surface - modified with siloxane.

[0035] In some embodiments, the preparation method of the modified alumina includes the following steps: immersing the spherical alumina in a modified solution dissolved with a siloxane surface modifier, stirring and dispersing, and then filtering and drying to obtain the modified alumina. In fact, when immersing the spherical alumina in the modified solution, the particle size of the spherical alumina used is 5 - 30μm.

[0036] In some embodiments, when spherical alumina is immersed in a modification solution in which a siloxane surface modifier is dissolved, the siloxane surface modifier dissolved in the modification solution may include at least one of γ-aminopropyltrimethoxysilane (γ-APS), γ-glycidoxypropyltrimethoxysilane (KH560), and γ-aminopropyltriethoxysilane (KH550). In some embodiments, the solid-liquid ratio when the spherical alumina is dispersed in the modification solution is 0.05 - 0.09, preferably the solid-liquid ratio may be 0.07, and the modification solution may be a saturated solution of the siloxane surface modifier.

[0037] In fact, the present invention also provides an application of a phase change cooling coating, a phase change cooling coating layer, and a composite phase change coating on the surface of a photovoltaic module, and at least one layer of the phase change cooling coating is cured on the back surface of the photovoltaic module.

[0038] Preparation Example 1

[0039] This Preparation Example 1 provides a method for preparing modified alumina, which includes the following steps: adding 3.0 g of spherical alumina with a particle size of 5 - 30 μm into a modification solution, controlling the solid-liquid ratio to be 0.07, stirring and dispersing at 60 °C for 60 min, and then filtering and drying to obtain modified alumina; wherein, the modification solution is a KH560 solution with a concentration of 0.084 mol / L.

[0040] Example 1

[0041] This Example 1 provides a method for preparing a phase change cooling coating, which includes the following steps:

[0042] S1. Add polyvinylidene fluoride - hexafluoropropylene copolymer (PVDF - HFP) into N,N - dimethylformamide (DMF) solvent, and magnetically stir at 50 °C and a rotation speed of 800 rpm for 15 min to obtain a precursor solution;

[0043] S2. Add acrylic resin (the mass ratio of PVDF - HFP to acrylic resin is 70:30) into the precursor solution, and magnetically stir at 50 °C and a rotation speed of 800 rpm for 15 min to obtain a precursor coating;

[0044] S3. Add 65.8 wt% of myristyl alcohol into the precursor coating, magnetically stir at 50 °C and a rotation speed of 800 rpm for 30 min, then add 2.6 wt% of hydrophobic fumed silica, and continue to stir for 60 min to form a white viscous suspension; then add 2.4 wt% of graphene into the suspension, magnetically stir at a rotation speed of 1000 rpm for 60 min, and then stand at room temperature to defoam to obtain a black viscous composite phase change coating.

[0045] Example 2

[0046] Example 2 provides a preparation method of a phase change cooling coating. The difference from Example 1 is that the mass fraction of tetradecanol in step S3 is 60.7%.

[0047] Example 3

[0048] Example 3 provides a preparation method of a phase change cooling coating. The difference from Example 1 is that the mass fraction of tetradecanol in step S3 is 53%.

[0049] Example 4

[0050] Example 4 provides a preparation method of a phase change cooling coating. The difference from Example 1 is that the mass fraction of tetradecanol in step S3 is 34%.

[0051] Example 5

[0052] Example 5 provides a preparation method of a radiative cooling coating, including the following steps:

[0053] Y1. Add 3.0 g of poly(vinylidene fluoride - hexafluoropropylene) copolymer (PVDF - HFP) into 20 mL of N,N - dimethylformamide (DMF) and stir to dissolve to obtain a precursor solution;

[0054] S2. Add 0.9 g of acrylic resin into the precursor solution, and magnetically stir at 30 °C and a mechanical rotation speed of 600 rpm for 30 min to form a milky white viscous precursor coating;

[0055] S3. Add the modified alumina prepared in Preparation Example 1 into the precursor coating, magnetically stir at 30 °C and a rotation speed of 600 rpm for 10 min, then add graphene and 0.1 mL of dispersant BYK - 180, magnetically stir at 30 °C and a rotation speed of 600 rpm for 120 min, and then ultrasonically disperse for 20 min using an ultrasonic cell disrupter of model BILON - 1000Y, and let it stand to defoam to obtain a black viscous radiative cooling coating; among them, the mass fraction of modified alumina in the radiative cooling coating is 0.75% and the mass fraction of graphene is 1%.

[0056] Comparative Example 1

[0057] Comparative Example 1 provides a preparation method of a phase change cooling coating. The difference from Example 1 is that hydrophobic fumed silica and graphene are not added in step S3, and layering occurs after stirring, making it difficult to obtain a stable phase change cooling coating.

[0058] Application Examples 1 to 4

[0059] Application Examples 1 to 4 respectively provide an application of a composite cooling coating on the back of a photovoltaic module, including: using a coater to scrape the phase change cooling coatings prepared in Examples 1 to 4 on the back of the photovoltaic module, and drying and curing in a vacuum drying oven at 50°C; then using a coater to scrape the radiative cooling coating prepared in Example 5 on the surface of the phase change cooling coating, and drying and curing in a vacuum drying oven at 50°C.

[0060] Application Example 5

[0061] Application Example 5 provides an application of a radiative cooling coating on the back of a photovoltaic module, including: using a coater to scrape the radiative cooling coating prepared in Example 5 on the back of the photovoltaic module, and drying and curing in a vacuum drying oven at 50°C.

[0062] Performance tests were carried out on the photovoltaic modules in Application Examples 1 to 5, and the results are shown in Table 1 below. Figures 2 to 4 as shown.

[0063] Table 1 Performance Indexes of Composite Cooling Coating

[0064]

[0065] Combined with Examples 1 to 4 and Comparative Example 2, it can be seen that the present invention adds fumed silica and graphene to the phase change coating, which improves the viscosity of the coating, enables the phase change material to stably exist in the phase change coating, and at the same time, when the coating is cured to form a coating, silica and graphene can form a three-dimensional heat conduction network in the coating, thereby effectively improving the heat conduction performance of the coating.

[0066] Combined with Application Example 1 and Application Example 5, it can be seen that after the present invention introduces a phase change cooling coating, the latent heat of phase change of the phase change material is used to absorb the heat of the photovoltaic module, significantly improving the cooling amplitude of the photovoltaic module. From Figure 3 it can be seen that when the solar irradiance is 650 W / m 2 ², the maximum cooling amplitude of the photovoltaic module coated with the cooling coating is ~6°C.

[0067] From Figure 4 it can be seen that according to Figure 4 the relationship between the module temperature and the maximum output power, when the average solar irradiance is 600 W / m 2 ², the temperature of the control group is higher than that of the experimental group, and the maximum output power is lower than that of the experimental group. The maximum output power of the experimental group is 0.764 W, and the maximum output power of the control group is 0.699 W. Thus, it can be seen that the heat dissipation coating can improve the output power of the module, and its output power is relatively increased by about 9.3%. According to Figure 4From the relationship between the component temperature and its photoelectric conversion efficiency, it can be seen that the conversion efficiency of the control group is lower than that of the experimental group. Among them, the conversion efficiency of the experimental group is 5.5%, and the conversion efficiency of the control group is 4.8%. The heat dissipation coating relatively increases the conversion efficiency of the photovoltaic module by about 13.6%.

[0068] Although the embodiments of the present invention have been described in detail above, it is obvious to those skilled in the art that various modifications and changes can be made to these embodiments. However, it should be understood that such modifications and changes are all within the scope and spirit of the present invention described in the claims. Moreover, the present invention described herein may have other embodiments and can be implemented or realized in various ways.

Claims

1. A preparation method of a phase change cooling coating, characterized in that, Comprising: Stirring and dissolving poly(vinylidene fluoride - hexafluoropropylene) copolymer in a polar aprotic solvent to obtain a precursor solution; Adding an acrylic resin to the precursor solution and stirring to disperse to obtain a precursor coating; Adding a phase change material, hydrophobic silica nanoparticles and graphene to the precursor coating and stirring to disperse to obtain a composite phase change coating; the phase change material includes n - tetradecanol, n - octadecanol or polyethylene glycol.

2. The preparation method according to claim 1, wherein When adding the acrylic resin to the precursor solution and stirring to disperse, the mass percentage of the poly(vinylidene fluoride - hexafluoropropylene) copolymer in the mixture formed by the acrylic resin and the poly(vinylidene fluoride - hexafluoropropylene) copolymer is 60% - 80%.

3. The preparation method according to claim 1, characterized in that The polar aprotic solvent is N,N - dimethylformamide, N,N - dimethylacetamide or N - methylpyrrolidone; and / or, the particle size of the hydrophobic silica nanoparticles is 7nm - 20nm; and / or, the mass ratio of the graphene to the poly(vinylidene fluoride - hexafluoropropylene) copolymer is 0.5 - 2.0%.

4. A phase change cooling coating prepared by the preparation method according to any one of claims 1 to 3.

5. A phase change cooling coating prepared by the preparation method according to any one of claims 1 to 3 or a phase change cooling coating formed after curing of the phase change cooling coating according to claim 4.

6. A composite phase change coating, characterized in that, Having at least one layer of the phase change cooling coating according to claim 5.

7. The composite phase change coating according to claim 6, wherein Comprising a phase change cooling coating and a radiative cooling coating that are superposed on each other, and the composite cooling coating is formed by curing a radiative cooling coating.

8. The composite phase change coating according to claim 7, wherein The preparation method of the radiative cooling coating includes: adding modified alumina and graphene to the precursor coating and stirring to disperse to obtain a radiative cooling coating; wherein, the modified alumina is spherical alumina surface - modified with siloxane.

9. The application of a phase change cooling coating prepared by the preparation method according to any one of claims 1 to 3, or a phase change cooling coating according to claim 5, or a composite phase change coating according to any one of claims 6 to 8 on the surface of a photovoltaic module.

10. The application according to claim 9, wherein, At least one layer of the phase change cooling coating is cured on the back of the photovoltaic module.

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