A spectroscopic aerogel solar collector tube and its preparation method

Abstract

This invention provides a spectrally selective aerogel solar collector tube and its preparation method, comprising a glass tube, an aerogel matrix, nanoparticles with spectrally selective absorption filled within the aerogel matrix, and an antireflective film. The aerogel matrix has a porous structure and is tightly attached to the outer wall of the glass tube. The nanoparticles within the aerogel matrix form a gradient absorption layer structure with gradually increasing filling factor from the outside to the inside, thereby selectively absorbing different spectra of sunlight and converting them into heat energy. The antireflective film is a silicon-based high-transmittance material and is attached to the outer wall of the aerogel matrix and the inner wall of the glass tube. This invention replaces the outer glass tube, vacuum layer, and selective absorption film of traditional solar collector tubes with an aerogel matrix containing nanoparticles, achieving high absorption and high transmittance of different spectra of sunlight, thus improving the overall efficiency of solar energy utilization.

Description

Technical Field

[0001] This invention belongs to the field of solar energy, specifically relating to a spectroscopic aerogel solar collector tube and its preparation method. Background Technology

[0002] Hydrogen energy is a crucial clean energy source for the future, and photocatalytic water or biomass hydrogen production using renewable solar energy has a very broad application prospect. However, in solar photocatalytic water or biomass hydrogen production, the utilization rate of solar energy is very low because only the short-wavelength portion of the solar spectrum (250nm-2500nm), such as below 600nm, can be utilized for photocatalysis. To further improve the utilization rate of solar energy and the efficiency of hydrogen production, the use of photothermal synergistic catalytic hydrogen production has gradually become a research hotspot in solar hydrogen production. Therefore, in order to simultaneously achieve the photothermal conversion and photocatalysis of sunlight, it is necessary to develop solar collectors with spectral utilization capabilities. On the one hand, this requires that the sunlight of the spectrum required for photocatalysis can enter the fluid in the collector; on the other hand, it is necessary to convert the remaining solar spectrum into heat energy for the fluid.

[0003] Currently, traditional all-glass vacuum collector tubes are non-straight-through collector tubes. A vacuum layer exists between the outer and inner glass tubes to reduce heat loss. The selective absorption film on the inner glass tube is opaque, making it difficult for sunlight to directly enter the fluid for photocatalysis; it can only heat the fluid inside the tube. Furthermore, hot and cold fluids can only enter and exit through the same port, making it difficult to apply in solar-thermal synergistic catalytic hydrogen production. Another type of solar collector tube is the straight-through glass-metal structure collector tube, with a metal inner tube and a glass outer tube. To mitigate the thermal expansion difference between the metal inner tube and the glass outer tube, corrugated pipes are needed at the ends to prevent damage to the glass outer tube due to tensile stress. A vacuum is also required between the glass outer tube and the metal inner tube to reduce heat loss. However, because the metal inner tube can only heat the fluid inside the tube and cannot allow sunlight to enter the fluid for photocatalysis, it is also difficult to apply in solar-thermal synergistic catalytic hydrogen production. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention proposes a spectral-splitting aerogel solar collector tube and its preparation method. This achieves the absorption and transmission of sunlight in different wavelengths, eliminating the need for an outer glass tube and vacuum layer, reducing heat loss and manufacturing processes, and improving the overall efficiency of solar energy utilization. This invention uses a translucent aerogel for insulation on the outside of the glass tube, and achieves the absorption and transmission of sunlight in different wavelengths by adjusting the nanoparticles within the aerogel. This not only solves the problem of not being able to connect in series due to the non-straight-through nature of traditional solar collector tubes, but also avoids damage caused by vacuuming and the thermal expansion difference between the inner and outer glass tubes, significantly improving the overall efficiency of solar energy utilization and operational economy.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A spectrally-divided aerogel solar collector tube comprises a glass tube, an aerogel matrix, nanoparticles with spectrally-divided absorption filling the aerogel matrix, and an antireflective film. The aerogel matrix has a porous structure and is tightly attached to the outer wall of the glass tube, with a thickness of 1-60 mm. The nanoparticles in the aerogel matrix form a gradient absorption layer structure with gradually increasing filling factor from the outside to the inside, thereby selectively absorbing different spectra of sunlight and converting them into heat energy. The antireflective film is a silicon-based high-transmittance material and is attached to the outer wall of the aerogel matrix and the inner wall of the glass tube. The total thermal conductivity of the aerogel matrix with nanoparticles does not exceed 0.2 W / (m·K).

[0007] Furthermore, the aerogel matrix is ​​a silica aerogel porous material with a maximum pore size of no more than 20 nm.

[0008] Furthermore, the nanoparticles are cesium-doped tungsten oxide nanoparticles or indium tin oxide nanoparticles, with an equivalent diameter ranging from 5 to 50 nm.

[0009] Furthermore, the filling factor of the nanoparticles in the aerogel matrix gradually increases from 0.01% to a maximum of no more than 5% from the outside to the inside, thereby achieving efficient absorption of the spectrum of sunlight with wavelengths above 600nm and efficient transmission of the spectrum with wavelengths below 600nm.

[0010] Furthermore, the antireflective coating layer has a thickness of 80-200 nm and a transmittance of over 95% in the solar spectrum range of 300-2500 nm.

[0011] Furthermore, the glass tube may have glass and metal sealing sections at both ends, for connecting multiple aerogel solar collector tubes with different spectra in series or in parallel; the glass and metal sealing sections adopt a double-sided sealing method in which glass is attached to the inner and outer walls of the metal.

[0012] This invention also provides a method for preparing a spectroscopic aerogel solar collector tube, comprising the following steps:

[0013] Step ① Prepare the nanoparticle material, aerogel material, and antireflective membrane material separately;

[0014] Step 2: Add nanoparticle materials to multiple portions of aerogel material according to different filler factors to form multiple portions of aerogel material with different nanoparticle filler factors.

[0015] After cleaning and drying, the aerogel material from step ② is sequentially coated onto the outer wall of the glass tube in descending order of nanoparticle filler factor, and then heated, dried and cured to form an aerogel matrix with nanoparticles.

[0016] Step 4: The antireflective membrane material is impregnated onto a glass tube with an aerogel matrix using the sol-gel method, and then heated, dried and cured to complete the preparation of the spectroscopic aerogel solar collector tube.

[0017] The technical advantages of this invention are:

[0018] 1) The outer glass tube has an aerogel matrix that replaces the vacuum layer to provide thermal insulation, eliminating the need for vacuuming and an outer glass tube, thus simplifying the manufacturing process.

[0019] 2) The nanoparticles form a gradually increasing absorption layer structure within the aerogel matrix, which enables selective spectral utilization of sunlight and improves the overall efficiency of solar energy utilization.

[0020] 3) The antireflective coating has high wear resistance and high light transmittance, which can protect the aerogel matrix and increase the wear resistance and light transmittance of the heat collection tube. Attached Figure Description

[0021] Figure 1 This is a cross-sectional view of the solar collector tube according to Embodiment 1 of the present invention;

[0022] Figure 2 This is a longitudinal cross-sectional view of the solar collector tube of Embodiment 1 of the present invention;

[0023] Figure 3 This is a cross-sectional view of the solar collector tube in Embodiment 2 of the present invention;

[0024] Figure 4 This is a longitudinal cross-sectional view of the solar collector tube of Embodiment 3 of the present invention.

[0025] In the figure: 1-glass tube, 2-aerogel matrix, 3-nanoparticles, 4-antireflective film, 5-metal-glass sealing section. Detailed Implementation

[0026] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0027] like Figure 1 and Figure 2As shown, an embodiment 1 of the present invention provides a spectrally spectrally oriented aerogel solar collector tube comprising a glass tube 1, an aerogel matrix 2, nanoparticles 3 with spectrally oriented absorption filled within the aerogel matrix 2, and an antireflective membrane 4. The aerogel matrix 2 is a porous silica aerogel material with a maximum pore size not exceeding 10 nm, tightly adhered to the outer wall of the glass tube 1, and has a thickness of 60 mm. The nanoparticles 3 are cesium-doped tungsten oxide nanoparticles with an equivalent diameter ranging from 5 to 10 nm, and their fill factor within the aerogel matrix 2 is 0.01 from the outside to the inside. The gradient absorption layer structure gradually increases from % to 2%, thereby achieving efficient absorption of wavelengths above 600nm in sunlight and efficient transmission of wavelengths below 600nm. The antireflective film 4 is a silicon-based high-transmittance material with a thickness of 120nm. Its transmittance exceeds 95% in the solar spectrum range of 300-2500nm. The antireflective film 4 is attached to the outer wall of the aerogel matrix 2 and the inner wall of the glass tube 1. The total thermal conductivity of the aerogel matrix 2 with nanoparticles 3 does not exceed 0.1W / (m·K).

[0028] The method for preparing the spectroscopic aerogel solar collector tube in Embodiment 1 of the present invention includes the following steps:

[0029] Step ① Prepare the cesium-doped tungsten oxide nanoparticles, aerogel materials, and antireflection membrane materials respectively;

[0030] Step 2: Add nanoparticle materials to multiple portions of aerogel material according to different filler factors to form multiple portions of aerogel material with different nanoparticle filler factors.

[0031] Step ③ After cleaning and drying the glass tube, the aerogel material from Step ② is sequentially coated onto the outer wall of the glass tube in descending order of nanoparticle filler factor, and then heated, dried and cured to form an aerogel matrix with nanoparticles.

[0032] Step 4: The antireflective membrane material is impregnated onto a glass tube with an aerogel matrix using the sol-gel method, and then heated, dried and cured to complete the preparation of the spectroscopic aerogel solar collector tube.

[0033] like Figure 3 and Figure 4As shown, an embodiment 2 of the present invention provides a spectral-divided aerogel solar collector tube comprising a glass tube 1, an aerogel matrix 2, nanoparticles 3 with spectral absorption capabilities filled within the aerogel matrix 2, an antireflective film layer 4, and metal-glass sealing sections 5 at both ends. The aerogel matrix 2 is a porous silica aerogel material with a maximum pore size not exceeding 20 nm, tightly adhered to the outer wall of the glass tube 1, and has a thickness of 40 mm. The nanoparticles 3 are indium tin oxide nanoparticles with an equivalent diameter ranging from 10 to 15 nm. Their fill factor within the aerogel matrix 2 gradually increases from 0.01% to 5% from the outside to the inside, forming a gradient absorption layer structure, thereby achieving absorption of more than 50% of sunlight. It efficiently absorbs wavelengths above 0 nm and efficiently transmits wavelengths below 500 nm; the antireflective coating 4 is a silicon-based high-transmittance material with a thickness of 200 nm, and its transmittance exceeds 95% in the solar spectrum range of 300-2500 nm. The antireflective coating 4 is attached to the outer wall of the aerogel matrix and the inner wall of the glass tube; the total thermal conductivity of the aerogel matrix 2 with nanoparticles 3 does not exceed 0.2 W / (m·K); the metal-glass sealing section 5 adopts a double-sided sealing method in which glass is attached to the inner and outer walls of the metal to ensure the sealing strength. Through the metal-glass sealing section 5, multiple aerogel solar collector tubes with different wavelengths can be connected in series or in parallel.

[0034] The method for preparing the spectral aerogel solar collector tube in Embodiment 2 of the present invention includes the following steps:

[0035] Step ① Prepare indium tin oxide nanoparticles, aerogel materials, and antireflection membrane materials respectively;

[0036] Step 2: Add nanoparticle materials to multiple portions of aerogel material according to different filler factors to form multiple portions of aerogel material with different nanoparticle filler factors.

[0037] Step ③ After cleaning and drying, the aerogel material from Step ② is sequentially coated onto the outer wall of the glass tube with glass and metal sealing sections in descending order of nanoparticle filler factor, and then heated, dried and cured to form an aerogel matrix with nanoparticles.

[0038] Step 4: The antireflective membrane material is impregnated onto a glass tube with an aerogel matrix using the sol-gel method, and then heated, dried and cured to complete the preparation of the spectroscopic aerogel solar collector tube.

[0039] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A spectral-splitting aerogel solar collector tube, characterized in that: The aerogel matrix includes a glass tube (1), an aerogel matrix (2), nanoparticles (3) with spectral absorption filled in the aerogel matrix (2), and an antireflective film (4). The aerogel matrix (2) has a porous structure and is tightly attached to the outer wall of the glass tube (1), with a thickness of 1-60 mm. The nanoparticles (3) in the aerogel matrix (2) form a gradient absorption layer structure with gradually increasing filling factor from the outside to the inside, thereby selectively absorbing different spectra of sunlight and converting them into heat energy. The antireflective film (4) is a silicon-based high-transmittance material and is attached to the outer wall of the aerogel matrix (2) and the inner wall of the glass tube (1). The total thermal conductivity of the aerogel matrix (2) with nanoparticles (3) does not exceed 0.2 W / (m·K).

2. The aerogel solar collector tube with spectral dispersion according to claim 1, characterized in that: The aerogel matrix (2) is a silica aerogel porous material with a maximum pore size of 20 nm.

3. The aerogel solar collector tube with split spectrum according to claim 1, characterized in that: The nanoparticles (3) are cesium-doped tungsten oxide nanoparticles or indium tin oxide nanoparticles, with an equivalent diameter ranging from 5 to 50 nm.

4. A spectroscopic aerogel solar collector tube according to claim 1 or 3, characterized in that: The nanoparticles (3) gradually increase in filling factor from 0.01% to 5% from the outside to the inside of the aerogel matrix (2), thereby achieving efficient absorption of the spectrum of sunlight with wavelengths above 600nm and efficient transmission of the spectrum with wavelengths below 600nm.

5. The aerogel solar collector tube with split spectrum according to claim 1, characterized in that: The antireflective coating (4) has a thickness of 80-200 nm and a transmittance of over 95% in the solar spectrum range of 300-2500 nm.

6. The aerogel solar collector tube with split spectrum according to claim 1, characterized in that: The glass tube (1) also has metal and glass sealing sections (5) at both ends, which are used for the aerogel solar collector tubes with multiple spectra to be connected in series or in parallel.

7. A spectroscopic aerogel solar collector tube according to claim 6, characterized in that, The metal-glass sealing section (5) adopts a double-sided sealing method in which glass is attached to the inner and outer walls of the metal.

8. A method for preparing a spectroscopic aerogel solar collector tube according to any one of claims 1-7, characterized in that, Includes the following steps: Step ① Prepare the nanoparticle material, aerogel material, and antireflective membrane material separately; Step 2: The nanoparticle material is added to multiple portions of aerogel material according to different filler factors to form multiple portions of aerogel material with different nanoparticle filler factors. After cleaning and drying, the aerogel material from step ② is sequentially coated onto the outer wall of the glass tube (1) in descending order of nanoparticle filling factor, and then heated, dried and cured to form an aerogel matrix (2) with nanoparticles (3). Step 4: The antireflective membrane material is impregnated on a glass tube (1) with an aerogel matrix (2) using the sol-gel method, and then heated, dried and cured to complete the preparation of the spectroscopic aerogel solar collector tube.

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