An ultra-high reflectance high weatherability frost-resistant sandwich mirror for concentrating collectors

Abstract

This invention discloses an ultra-high reflectivity, high weather resistance, and frost-resistant sandwich reflector for concentrating solar collectors. An anti-frost and snow-resistant superhydrophobic coating is located on the upper surface of ultra-clear semi-tempered float glass. A first anti-reflection layer is located on the lower surface of the ultra-clear semi-tempered float glass. A reflective layer is located on the lower surface of the first anti-reflection layer, an anti-reflective layer is located on the lower surface of the reflective layer, a metal-doped absorbing layer is located on the lower surface of the anti-reflective layer, and a second anti-reflection layer is located on the lower surface of the metal-doped absorbing layer. A fully tempered float glass support is bonded to the second anti-reflection layer on the lower surface of the ultra-clear semi-tempered float glass using a vacuum lamination process, forming a sandwich concentrating reflector. The edges of the sandwich concentrating reflector are sealed with an edge sealant. This invention not only ensures a reflectivity of 95.5-97% but also exhibits strong weather resistance, significantly reducing the defrosting time in winter, daily cleaning time and frequency, and slowing down the decay of reflectivity, thus extending its service life.

Description

Technical Field

[0001] This invention belongs to the field of solar collector tubes, and specifically relates to an ultra-high reflectivity, high weather resistance and anti-frost sandwich reflector for concentrating solar collectors. Background Technology

[0002] Concentrated solar thermal power generation systems utilize focusing solar collectors to convert solar radiation into heat energy, which is then used to generate electricity via a steam turbine and generator. Depending on the focusing method, concentrated solar thermal power generation systems are mainly classified as tower, trough, and dish types.

[0003] In concentrated solar power (CSP) systems, the optical focusing performance and weather resistance of the mirrors in the solar thermal field directly affect the overall photothermal conversion efficiency of the collecting field. Currently, existing CSP mirrors have the following drawbacks:

[0004] 1) Existing condenser mirrors use 4-5mm ultra-white float glass, which is hot-bent into the required shape. This easily produces ripples, causing optical performance distortion. At the same time, the back is chemically plated with silver, making it difficult to guarantee the uniformity and density of the reflective layer. Therefore, the reflectivity of current photothermal condenser mirrors is ≤94.5%.

[0005] 2) The back of the reflective layer uses expensive paint as a protective layer, which is not only costly, but also prone to damage due to aging or damage of the paint, which can lead to a decrease in reflectivity.

[0006] 3) In winter, the surface of the concentrating reflector is prone to frost formation, so it takes a long time (3-4 hours) every day to defrost using solar thermal energy, which reduces the utilization efficiency of the entire solar collector.

[0007] 4) To ensure the optical performance of the reflector, its surface needs to be kept clean to maximize its reflectivity. However, currently, reflectors are cleaned by washing with water, and to achieve a certain level of cleanliness, the cleaning frequency is generally once a week, which is costly.

[0008] (5) The structure is more complex than that of the current single ultra-white tempered glass focusing reflector, and there are many types of film systems. Therefore, the manufacturing process (including coating process and vacuum lamination process) and equipment requirements are high. Summary of the Invention

[0009] To address the aforementioned technical problems, this invention provides an ultra-high reflectivity, high weather resistance, and anti-frost sandwich reflector for concentrating solar collectors. This not only ensures a reflectivity of 95%-97% but also exhibits strong weather resistance, significantly reducing the defrosting time in winter, daily cleaning time, and cleaning frequency of the concentrating reflector. It also slows down the decay of reflectivity and extends its service life.

[0010] The main technical solution adopted in this invention is as follows:

[0011] A high-reflectivity, high-weather-resistant, frost-resistant sandwich reflector for concentrating solar collectors includes an anti-frost and snow superhydrophobic coating, ultra-clear semi-tempered float glass, a first anti-reflection layer, a reflective layer, an anti-reflective layer, a metal-doped absorbing layer, a second anti-reflection layer, and a float glass support. The anti-frost and snow superhydrophobic coating is located on the upper surface of the ultra-clear semi-tempered float glass, the first anti-reflection layer is located on the lower surface of the ultra-clear semi-tempered float glass, the reflective layer is located on the lower surface of the first anti-reflection layer, the anti-reflective layer is located on the lower surface of the reflective layer, the metal-doped absorbing layer is located on the lower surface of the anti-reflective layer, and the second anti-reflection layer is located on the lower surface of the metal-doped absorbing layer. The float glass support is bonded to the second anti-reflection layer on the lower surface of the ultra-clear semi-tempered float glass using a vacuum lamination process via an adhesive layer to form a sandwich concentrating reflector. The sandwich concentrating reflector is edge-sealed with an edge sealant.

[0012] Preferably, the anti-frost and snow superhydrophobic coating is a silicone-based nanomaterial coating, and the thickness of the anti-frost and snow superhydrophobic coating is 150nm-200nm.

[0013] Preferably, the ultra-white semi-tempered float glass is low-iron ultra-white float glass, and the thickness of the ultra-white semi-tempered float glass is 1~1.8mm.

[0014] Preferably, the ultra-white semi-tempered float glass has a planar structure before lamination.

[0015] Preferably, both the first antireflection layer and the second antireflection layer are SiO2 antireflection layers, the thickness of the first antireflection layer is 50-100 nm, and the thickness of the second antireflection layer is 100-200 nm.

[0016] Preferably, the reflective layer is an Ag reflective layer with a thickness of 150~250nm.

[0017] Preferably, the anti-reflection layer is a Cu anti-reflection layer with a thickness of 100~150nm.

[0018] Preferably, the metal-doped absorption layer is a multilayer metal-doped absorption layer, comprising, from near to far from the ultra-white semi-tempered float glass, a high-volume metal-doped absorption layer, a medium-volume metal-doped absorption layer, and a low-volume metal-doped absorption layer. The high-volume metal-doped absorption layer has a metal doping ratio of 55%–65% and a thickness of 100–220 nm; the medium-volume metal-doped absorption layer has a metal doping ratio of 40%–55% and a thickness of 100–220 nm; the medium-volume metal-doped absorption layer of the low-volume metal-doped absorption layer has a metal doping ratio of 30%–40% and a thickness of 100–220 nm; and the high-volume, medium-volume, and low-volume metal-doped absorption layers are either SS+AlSiOx or SS+AlN metal-doped absorption layers.

[0019] Preferably, the adhesive layer is made of translucent EVA or POE material.

[0020] Preferably, the thickness of the float glass support is 3-5 mm.

[0021] Beneficial effects: This invention provides an ultra-high reflectivity, high weather resistance, and frost-proof sandwich reflector for concentrating solar collectors, which has the following advantages:

[0022] (1) The ultra-white semi-tempered float glass has a planar structure before lamination, which can reduce wind ripples and optical performance distortion, and improve transmittance;

[0023] (2) The present invention has strong weather resistance, which greatly shortens the defrosting time in winter, daily cleaning time and cleaning frequency of the concentrating reflector;

[0024] (3) The reflective layer and the absorber layer of the present invention are both located between vacuum-laminated double-layer glass, which makes the coating have a longer service life and a slower attenuation of reflectivity.

[0025] (4) The present invention adopts the absorption layer structure design of sandwich reflector and controls the temperature change range of the adhesive layer caused by the absorption energy to be 45~80℃. On the one hand, it can ensure rapid defrosting in winter, and on the other hand, it can prevent the adhesive layer from being damaged in summer.

[0026] (5) The anti-frost and snow superhydrophobic coating on the outer surface of the laminated reflective glass (ultra-white semi-tempered float glass) has a self-cleaning function, reducing frost and snow. Attached Figure Description

[0027] Figure 1 This is an overall structural diagram of the present invention.

[0028] Figure 2 This is a schematic diagram of the structure after step S1 in Example 1.

[0029] Figure 3 The emissivity spectrum is shown in Example 1.

[0030] Figure 4 This is the emissivity spectrum for comparison.

[0031] In the figure: 1. Anti-frost and snow superhydrophobic coating; 2. Ultra-white semi-tempered float glass; 3. First SiO2 antireflective layer; 4. Ag reflective layer; 5. Cu antireflective layer; 6-1. High-volume metal doped absorption layer; 6-2. Medium-volume metal doped absorption layer; 6-3. Low-volume metal doped absorption layer; 7. Second SiO2 antireflective layer; 8. Adhesive layer; 9. Float fully tempered glass support; 10. Edge sealant. Detailed Implementation

[0032] To enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application are clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this application.

[0033] Example 1

[0034] like Figure 1 As shown, a high-reflectivity, high-weather-resistant, and frost-resistant sandwich reflector for a concentrating solar collector comprises, from the outside to the inside, an anti-frost and snow superhydrophobic coating 1, an ultra-white semi-tempered float glass 2, a first SiO2 antireflection layer 3, an Ag reflective layer 4, a Cu antireflection layer 5, a high-volume metal-doped absorption layer 6-1, a medium-volume metal-doped absorption layer 6-2, a low-volume metal-doped absorption layer 6-3, a second SiO2 antireflection layer 7, an adhesive layer 8, and a float fully tempered glass support 9.

[0035] In this embodiment, the anti-frost and snow superhydrophobic coating 1 is located on the outer surface of the ultra-clear semi-tempered float glass 2. The anti-frost and snow superhydrophobic coating 1 is a silicone-based nanomaterial that forms a transparent superhydrophobic film on the surface of the ultra-clear semi-tempered float glass 2. It can increase the transmittance of the glass substrate by more than 1%, and also has anti-frost, anti-snow, and self-cleaning functions. The anti-frost and snow superhydrophobic coating 1 can be applied using either dip coating or spray coating processes. The thickness of the anti-frost and snow superhydrophobic coating 1 is 150nm-200nm, and it can be naturally air-dried under sunlight in outdoor environments.

[0036] The ultra-white semi-tempered float glass 2 is a low-iron ultra-white float glass with a planar structure before lamination, and its thickness is 1~1.8mm, in order to increase light transmittance and flexibility. Since the ultra-white semi-tempered float glass 2 has a planar structure before lamination, it can reduce wind ripples and optical performance distortion, and improve transmittance.

[0037] The first SiO2 anti-reflection layer 3 is located on the inner surface of the ultra-white semi-tempered float glass 2, which can further improve the transmittance. Its thickness is 50~100nm.

[0038] The Ag reflective layer 4 is located on the lower surface of the SiO2 antireflective layer 3 and is the reflective layer of the ultra-white semi-tempered float glass 2, with a thickness of 150~250nm.

[0039] The Cu reflective layer 5 is located on the lower surface of the Ag reflective layer 4 to further improve reflectivity, with a thickness of 100~150nm.

[0040] The high-volume metal-doped absorber layer 6-1 is located below the Cu reflectance layer 5, with a metal doping ratio of 65%~55% and a thickness of 100~220nm.

[0041] The medium-volume metal-doped absorber layer 6-2 is located below the high-volume metal-doped absorber layer 6-1, with a metal doping ratio of 55% to 40% and a thickness of 100 to 220 nm.

[0042] The low-volume metal-doped absorber layer 6-3 is located below the medium-volume metal-doped absorber layer 6-2, with a metal doping ratio of 40% to 30% and a thickness of 100 to 220 nm.

[0043] Among them, the high-volume metal-doped absorption layer 6-1, the medium-volume metal-doped absorption layer 6-2, and the low-volume metal-doped absorption layer 6-3 are SS+AlSiOx absorption layers or SS+AlN absorption layers, where SS is stainless steel doping, AlSiOx is a mixture of Al2O3 and SiO2, and x represents the number of O atoms, which is an uncertain value.

[0044] The second SiO2 antireflection layer 7 is located below the low-volume metal-doped absorption layer 6-3, and its thickness is 100~200nm.

[0045] The bonding layer 8 is made of transparent EVA or POE. Its vacuum lamination process has a vacuum heat treatment function for all coatings on the inner surface of the ultra-white semi-tempered float glass 2. It not only changes the microstructure at the micro level, further eliminates dissolved moisture and gas, and improves the reflectivity (about 0.5%), but also plays a good protective role for the microstructure of the coating, further improving the density and toughness of the coating. Therefore, the reflectivity after vacuum lamination is 95.5%~97%.

[0046] The thickness of the float glass support 9 is 3~5mm, and it is made into a curved or flat surface according to the design requirements based on different types of solar collectors.

[0047] The edge sealant 10 is a liquid made by mixing modified acrylic resin and ethyl acetate in a certain proportion (existing technology). It is applied to the perimeter of the sandwich mirror by brushing to prevent moisture in the atmosphere from penetrating into the adhesive layer and to protect the adhesive layer from hydrolysis and damage.

[0048] In this invention, for trough-type solar collectors, the float glass support 9 needs to be pre-bent into the required parabolic surface.

[0049] The fabrication steps of the sandwich mirror in Embodiment 1 of the present invention are as follows:

[0050] S1: A first SiO2 antireflection layer 3, an Ag reflective layer 4, a Cu antireflection layer 5, a high-volume metal-doped absorption layer 6-1, a medium-volume metal-doped absorption layer 6-2, a low-volume metal-doped absorption layer 6-3, and a second SiO2 antireflection layer 7 are sequentially formed on the inner surface of ultra-white semi-tempered float glass 2 using a vacuum magnetron sputtering process. Figure 2 As shown;

[0051] S2: Using vacuum lamination process and support mold, the ultra-white semi-tempered float glass 2, which has completed vacuum magnetic sputtering coating, is bonded together with the float fully tempered glass support 9 using the adhesive layer 8. The ultra-white semi-tempered float glass 2 is bonded together with the float fully tempered glass support 9 as the shape changes during the lamination process, forming a sandwiched light-concentrating reflector.

[0052] S3: Use edge sealing agent 10 to seal the edge of the interlayer focusing mirror to prevent moisture and water vapor in the atmosphere from hydrolyzing the adhesive.

[0053] S4: Apply an anti-frost and snow superhydrophobic coating 1 to the outer surface of the ultra-clear semi-tempered float glass 2 of the sandwich mirror using a dip coating or spray coating process to obtain the ultra-high reflectivity, high weather resistance, and anti-frost sandwich mirror of the present invention. Figure 1 As shown.

[0054] The working principle of this invention is as follows:

[0055] In this invention, an absorption layer is composed of a high-volume metal-doped absorption layer 6-1, a medium-volume metal-doped absorption layer 6-2, a low-volume metal-doped absorption layer 6-3, and a second SiO2 anti-reflection layer 7. During defrosting, the float glass support 9 is oriented towards the sun, allowing the absorption layer to absorb solar energy and transfer heat to the outer surface of the ultra-clear semi-tempered float glass 2, thus quickly melting the surface frost and achieving rapid defrosting. Furthermore, the heat absorbed by this absorption layer keeps the temperature of the adhesive material within the range of 45-80°C, preventing damage to the adhesive layer in summer (exceeding 80°C) and reducing defrosting efficiency in winter (due to excessively low outer surface temperature).

[0056] Comparison of the technical effects of Example 1 and the comparative example:

[0057] The ultra-white semi-tempered float glass 2 (i.e., the coated ultra-white semi-tempered float glass before lamination) that was coated sequentially by vacuum magnetron sputtering in step S1 is used as a comparative example.

[0058] (1) The reflectivity of the sandwiched condenser mirror prepared in Example 1 and the coated ultra-white semi-tempered float glass of the comparative example were tested respectively, as shown in the figure. Figure 3 and 4 As shown in the figure, the reflectivity of the pre-laminated ultra-white semi-tempered float glass (comparative example) is 95%-96.5%, while the reflectivity of the laminated focusing mirror (Example 1) after lamination is 95%-97%. This is because the vacuum lamination process of the adhesive material in the bonding layer has a vacuum heat treatment function on all coatings on the inner surface of the ultra-white semi-tempered float glass 2, which not only changes the microstructure at the micro level, further eliminates dissolved moisture and gas, and improves the reflectivity (by about 0.5%), but also plays a good protective role on the microstructure of the coating, further improving the density and toughness of the coating.

[0059] (2) The defrosting time of the sandwiched condenser mirror prepared in Example 1 and the coated ultra-white semi-tempered float glass of the comparative example were tested respectively. It was found that the defrosting time of Example 1 was shortened by 40-50% compared with the comparative example.

[0060] (3) An aging test was conducted on the sandwich condenser mirror prepared in Example 1, and it was found that the service life of the sandwich condenser mirror is ≥30 years, which meets the industry requirements.

[0061] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An ultra-high reflective, high weather resistant, frostable sandwich mirror for a concentrating solar collector, characterized in that, The system comprises an anti-frost and snow superhydrophobic coating, ultra-clear semi-tempered float glass, a first anti-reflective layer, a reflective layer, an anti-reflective layer, a metal-doped absorbing layer, a second anti-reflective layer, and a float fully tempered glass support. The anti-frost and snow superhydrophobic coating is located on the upper surface of the ultra-clear semi-tempered float glass, the first anti-reflective layer is located on the lower surface of the ultra-clear semi-tempered float glass, the reflective layer is located on the lower surface of the first anti-reflective layer, the anti-reflective layer is located on the lower surface of the reflective layer, the metal-doped absorbing layer is located on the lower surface of the anti-reflective layer, and the second anti-reflective layer is located on the lower surface of the metal-doped absorbing layer. The float fully tempered glass support is bonded to the second anti-reflective layer on the lower surface of the ultra-clear semi-tempered float glass using a vacuum lamination process through an adhesive layer, forming a sandwich-type focusing reflector. The sandwich-type focusing reflector is edge-sealed with an edge sealant. The metal-doped absorption layer is a multilayer metal-doped absorption layer, consisting of a high-volume metal-doped absorption layer, a medium-volume metal-doped absorption layer, and a low-volume metal-doped absorption layer, arranged sequentially from near to far from the ultra-white semi-tempered float glass. The high-volume metal-doped absorption layer has a metal doping ratio of 55%-65% and a thickness of 100-220 nm; the medium-volume metal-doped absorption layer has a metal doping ratio of 40%-55% and a thickness of 100-220 nm; and the low-volume metal-doped absorption layer has a metal doping ratio of 30%-40% and a thickness of 100-220 nm. The high-volume, medium-volume, and low-volume metal-doped absorption layers are either SS+AlSiOx or SS+AlN metal-doped absorption layers.

2. The super high reflective high weather resistant anti-frosting sandwich mirror for concentrating solar collector according to claim 1, characterized in that, The anti-frost and snow superhydrophobic coating is a silicon-based nanomaterial coating with a thickness of 150nm-200nm.

3. The super high reflective, high weather resistant, frostable sandwich mirror for concentrating solar collectors according to claim 1, wherein, The ultra-white semi-tempered float glass is low-iron ultra-white float glass, and the thickness of the ultra-white semi-tempered float glass is 1-1.8mm.

4. The super high reflective, high weather resistant, frostable sandwich mirror for a concentrating solar collector of claim 3, wherein, The ultra-white semi-tempered float glass has a planar structure before lamination.

5. The ultra-high reflectivity, high weather resistance, and frost-resistant sandwich reflector for concentrating solar collectors according to claim 1, characterized in that, Both the first and second antireflection layers are SiO2 antireflection layers, with the first antireflection layer having a thickness of 50-100 nm and the second antireflection layer having a thickness of 100-200 nm.

6. The ultra-high reflectivity, high weather resistance, and frost-resistant sandwich reflector for concentrating solar collectors according to claim 1, characterized in that, The reflective layer is an Ag reflective layer with a thickness of 150-250 nm.

7. The ultra-high reflectivity, high weather resistance, and frost-resistant sandwich reflector for concentrating solar collectors according to claim 1, characterized in that, The anti-reflection layer is a Cu anti-reflection layer with a thickness of 100-150 nm.

8. The ultra-high reflectivity, high weather resistance, and frost-resistant sandwich reflector for concentrating solar collectors according to claim 1, characterized in that, The adhesive layer is made of translucent EVA or POE material.

9. The ultra-high reflectivity, high weather resistance, and frost-resistant sandwich reflector for concentrating solar collectors according to claim 1, characterized in that, The thickness of the float glass support is 3-5mm.

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