A multi-layer modified quartz glass-based spectral air heat absorber for solar thermal power generation

Abstract

This invention discloses a multi-layer modified quartz glass-based spectroscopic air absorber for solar thermal power generation, relating to the field of solar thermal power generation absorbers. It includes a sealed cavity, a light-transmitting window, a multi-layer array of spectroscopically selective quartz glass plates, an airflow channel, inlet and outlet, and an insulation layer. The quartz glass plates are 3-5 mm thick, with a surface coated with a spectroscopically selective film resistant to temperatures above 800℃, or with metal oxide absorbing components introduced internally. They are arranged in layers according to the ultraviolet, visible, and infrared bands, and can form sub-arrays. The plate surface has fins or grooves to enhance heat transfer and airflow turbulence. Air undergoes multiple loops between layers, being heated step-by-step. The outer low-temperature quartz glass plates and the window effectively reflect the high-temperature long-wave radiation from the interior, reducing heat loss at the front end. This invention achieves volumetric absorption and cascaded utilization of light and heat along the depth of the cavity, significantly improving thermal efficiency and obtaining stable high-temperature air output.

Description

Technical Field

[0001] This invention relates to the field of solar thermal power generation receivers, and particularly to a multi-layer modified quartz glass-based spectral air receiver for solar thermal power generation. Background Technology

[0002] Tower solar thermal power generation technology, due to its high concentration ratio, can effectively improve the operating parameters of the working fluid, thereby increasing the system's power generation efficiency, and has become the mainstream technology for solar thermal power generation. In a solar thermal power plant, the receiver is the key component for the efficient conversion of solar radiation energy into working fluid heat energy, and its thermal efficiency directly determines the system's heat collection efficiency and power generation efficiency. Compared with liquid working fluids such as molten salt and heat transfer oil, air has advantages such as a high upper limit of operating temperature, no corrosion, no phase change, wide availability, and environmental friendliness, making it particularly suitable for driving high-temperature solar thermal power generation systems that utilize efficient Brayton cycles.

[0003] In high-temperature air heat absorption applications, especially when the target outlet temperature rises to approximately 800°C and above, the heat loss mechanism and efficiency bottleneck of the absorber become more prominent: the temperature of the light-receiving area increases significantly with the increase of the target temperature, and the radiative heat loss at high temperatures increases accordingly. The rapid increase in heat loss due to convection leads to a surge in radiative heat loss from the outer surface. Simultaneously, to obtain sufficient heat transfer driving force, the absorber often needs to maintain a surface temperature higher than the working fluid temperature, further compounding the convective and radiative heat losses from the outer surface, resulting in a significant decrease in thermal efficiency at high temperatures. Therefore, existing technologies have proposed various absorber structures and measures to "reduce heat loss and improve thermal efficiency," but overall, it remains difficult to balance high efficiency and reliability under high-temperature conditions, especially to achieve a stable arrangement of the high-temperature zone within the absorber to reduce heat loss from the outer surface.

[0004] Regarding volumetric heat absorbers for gaseous working media such as air, US patent application US4702174A discloses a ceramic honeycomb air absorber to increase the heat exchange area. However, due to the opacity of the material, solar radiation is mainly absorbed in the shallow layer at the inlet side, resulting in extremely high front-end surface temperature and low rear-end temperature. This leads to significant front-end radiative heat loss and limits the improvement of outlet temperature and high-temperature efficiency. Chinese patent application CN103486685A discloses a silicon carbide foam ceramic volumetric heat absorber that utilizes a three-dimensional mesh structure to enhance turbulent heat transfer. However, its absorption is still mainly based on the broad-spectrum absorption of a single material, and energy tends to concentrate and deposit at the front end, making it difficult to form a deep volumetric absorption temperature field with a "built-in high-temperature zone." Furthermore, foam ceramics are at risk of brittle failure under high-pressure airflow and thermal shock. Chinese patent application CN101968266A discloses a metal wire mesh stacked heat absorber, which increases the light transmission depth through stacking. However, the temperature resistance and oxidation resistance of metal materials are limited, and the surface emissivity is high, resulting in limited radiative heat loss at 800°C. Losses are difficult to suppress, limiting the improvement of thermal efficiency. European patent application EP2359074A1 regulates radiation penetration depth through a double-layer structure and porosity difference, but this type of geometric penetration regulation does not achieve graded capture from the perspective of spectral or material absorption mechanisms. There is still insufficient absorption or energy escape in the band with strong penetration ability, making it difficult to accurately control the depth of energy deposition and the location of the high-temperature zone. Chinese patent application CN105823189A discloses a quartz tube bundle air receiver with quartz tube pressure bearing and built-in heat absorber. Although it alleviates the pressure bearing problem, the thermal coupling between the heat absorber and the pressure bearing shell will push up the temperature of the quartz shell, bringing the risk of thermal stress failure, which is not conducive to the efficiency of the high-temperature section. US patent application US20100258116A1 discloses a pressurized air receiver with quartz window. The quartz window is mainly used to seal the light transmission and does not participate in the depth distribution of the absorption process. In order to avoid the window overheating, additional systems such as jet cooling are often required. Although it reduces the local temperature, it introduces additional power consumption and complexity, weakening the net efficiency. Meanwhile, in order to directly reduce the heat loss from high-temperature radiation, tower-type high-temperature receivers have proposed the idea of ​​a reflective cavity. US patent application US9917221A explicitly identifies the heat loss from infrared radiation at high temperatures as a key challenge for efficiency improvement and incorporates the radiation term into the efficiency expression. By setting up an infrared high-reflectivity cavity, the infrared radiation emitted by the absorber is reflected and reabsorbed within the cavity, thereby reducing the effective emissivity and improving the high-temperature photothermal efficiency. However, this type of solution mainly focuses on emission suppression and radiation recovery and cannot solve the problem of deep deposition and distribution of incident energy inside the absorber. High-temperature surface peaks may still form on the light-receiving side.

[0005] In summary, the existing technology has the following disadvantages:

[0006] (1) Traditional metal tubular air receivers are limited by the temperature resistance and opacity of the metal material, and mainly rely on heat absorption and surface convection on the surface of the tube wall to achieve energy transfer, resulting in a high concentration of heat on the outer surface. As the outlet temperature increases, the temperature of the light-receiving surface further increases to maintain the heat transfer driving force, causing the radiative heat loss on the outer surface to increase. The rapid increase in heat loss due to the convective heat loss leads to a significant decrease in thermal efficiency at high temperatures, making it difficult to maintain high heat absorption efficiency above 800℃.

[0007] (2) Although single-material volumetric heat absorbers such as foam ceramics and honeycomb ceramics can increase the specific surface area and enhance heat transfer through porous structures, the radiation energy decays exponentially along the incident direction and is concentrated in the shallow front end due to the single spectral absorption characteristics of the material. This results in local high temperature and large radiative heat loss at the front end, while the internal region has insufficient absorption and low effective heat transfer utilization, forming an energy distribution with large surface heat loss and weak internal absorption. This temperature field usually shows a decrease in temperature from front to back, which does not match the heat transfer demand of the air working fluid rising along the way. As a result, when pursuing a high outlet temperature, it is necessary to further increase the front surface temperature, thereby sacrificing higher radiative heat loss and limiting the improvement of overall thermal efficiency.

[0008] In existing air absorbers, significant thermal coupling often exists between the light-transmitting window and the absorber. Under high-temperature irradiation and temperature gradients, the window is prone to significant thermal stress and cracking failure. To ensure window reliability, engineering often incorporates measures such as window cooling, thickening, or multi-layer insulation. While these measures can reduce window temperature, they introduce additional energy consumption, structural obstruction, and extra thermal resistance, thereby reducing the system's net thermal efficiency. Furthermore, without effective spectral control, high-penetration wavelengths such as near-infrared are prone to transmission or reflection, resulting in optical efficiency loss. Ultraviolet wavelengths may cause thermal or photo-induced damage to the material at shallow layers, reducing the absorber's performance stability, ultimately leading to increased heat loss and decreased thermal efficiency. Summary of the Invention

[0009] To address the aforementioned technical problems, this invention provides a spectroscopic air absorber for solar thermal power generation based on multilayer modified quartz glass. It mainly comprises a sealed cavity, a light-transmitting window, a multilayer array of spectroscopically selective absorbing quartz glass plates located within the cavity, an air passageway, air inlets and outlets, and an insulation layer. The multilayer modified quartz glass plate array is arranged sequentially along the direction of solar radiation energy inflow. Each layer of quartz glass plate possesses specific spectral absorption characteristics by forming a spectroscopically selective absorption film on the surface of the quartz glass substrate. The spectroscopically selective absorption layer is formed by surface coating, with a quartz substrate thickness of 3 to 5 mm. The film can withstand operating temperatures above 800°C. The array's first layer is an ultraviolet absorption layer, the middle layer is a visible light absorption layer, and the bottom layer is an infrared cutoff absorption layer. Each absorption layer can be composed of multiple quartz glass plates with the same spectral characteristics forming a sub-array. Furthermore, the surface of the quartz substrate is provided with fins or grooved structures to expand the heat exchange area and enhance airflow turbulence. An airflow channel is formed between adjacent quartz glass plates. Air, constrained by the sealed cavity, is forced to flow through the gaps between the plates, creating multiple flow loops between the quartz glass plates of the same wavelength for interlayer cross-flow heat exchange. Air is then heated step-by-step by quartz glass plates with different temperature gradients. An insulation layer covers the non-transparent surface of the sealed cavity. This invention utilizes the spectral characteristics of modified quartz glass to achieve volume absorption along the cavity depth, placing the high-temperature zone inside the cavity. Simultaneously, the relatively low-temperature outer quartz glass plate and the light-transmitting window strongly absorb and reflect the high-temperature long-wave heat radiation from the interior, effectively blocking heat loss and significantly reducing radiation and convection heat loss at the front surface under high temperatures. This achieves volumetric conversion and efficient cascade utilization of photothermal energy within the cavity depth, resulting in high-temperature air with a stable outlet temperature and high thermal efficiency.

[0010] To achieve the above objectives, the present invention adopts the following technical solution:

[0011] A multi-layer modified quartz glass-based spectroscopic air absorber for solar thermal power generation includes a sealed cavity, a light-transmitting window, a multi-layer spectroscopically selective absorbing quartz glass plate array, an air guiding channel, a cold air inlet, a hot air outlet, an insulation layer, and a supporting structure. The overall layout of the absorber, from the outside in, consists of: an insulation layer wrapped around the outer wall of the cavity, a supporting structure, a sealed cavity, a light-transmitting window, and a multi-layer spectroscopically selective absorbing quartz glass plate array encapsulated inside the cavity. The multi-layer spectroscopically selective absorbing quartz glass plate array is arranged sequentially at intervals along the direction of solar radiation energy inflow, absorbing the air within the sealed cavity. The space is divided into sections; the air flow channel is formed by the gaps between adjacent quartz glass plates in the multi-layer spectrally selective absorption quartz glass plate array and the staggered opening structure of the quartz glass plates themselves, so that the air forms a multi-pass flow path between multiple quartz glass plates and forms a fluid path connecting the cold air inlet to the hot air outlet; solar radiation energy flows into the cavity through the light-transmitting window and irradiates the multi-layer spectrally selective absorption quartz glass plate array; the working air enters from the cold air inlet, is forced to flow through the air flow channel, is heated step by step by the quartz glass plates with different temperature gradients, and is discharged from the hot air outlet.

[0012] Furthermore, the multilayer spectrally selective absorption quartz glass plate array includes an ultraviolet absorption layer, a visible light absorption layer, and an infrared cutoff absorption layer arranged sequentially along the direction of solar radiation energy inflow, wherein the ultraviolet absorption layer is located at the front end, the visible light absorption layer is located in the middle, and the infrared cutoff absorption layer is located at the end. Each of the above absorption band layers can be constructed into a sub-array by connecting single or multiple quartz glass plates of different thicknesses with the same spectral characteristics according to the designed temperature distribution. By flexibly adjusting the number of quartz glass plates in each band, precise control of the solar spectral energy matching relationship and on-demand customization of the internal temperature field of the cavity can be achieved. At the same time, air is guided to travel back and forth between multiple quartz glass plates in the same band multiple times, forming a multi-pass baffle path to significantly increase the heat exchange path and residence time of the gas.

[0013] Furthermore, the ultraviolet absorption layer is a composite absorption structure constructed on a quartz glass substrate, comprising a CeO2 and TiO2-based inorganic oxide short-wavelength absorption film disposed on the substrate surface and / or CeO2 and TiO2 absorption components introduced into the quartz glass substrate, with a cutoff wavelength of approximately 500 nm, used to preferentially absorb ultraviolet and part of short-wave visible radiation, and in conjunction with the light-transmitting window, utilizes the high absorption and high reflection characteristics of the quartz substrate for long-wave thermal radiation to effectively block secondary thermal radiation emitted outward from the high-temperature region behind; the visible light absorption layer is a composite absorption structure constructed on a quartz glass substrate, comprising a high-temperature resistant all-oxide semi-transparent absorption film disposed on the substrate surface and / or a metal oxide absorption component introduced into the quartz glass substrate, wherein the all-oxide semi-transparent absorption film is selected from one or more of chromium oxide, iron oxide, cobalt oxide, nickel oxide, or manganese oxide and their composite systems, and may contain oxides. An aluminum, silicon dioxide, or zirconium oxide dielectric layer with an average full-spectrum absorptivity of 45%-55% and an average full-spectrum transmittance of 30%-35% is used to absorb the main energy in the visible light band while also allowing some transmission to achieve deep deposition. The infrared cutoff absorption layer is a composite absorption structure built on a quartz glass substrate, including a SiC high-temperature absorption layer or a black high-temperature resistant ceramic absorption coating disposed on the surface of the substrate and / or an infrared absorption component introduced into the quartz glass matrix, with a full-spectrum absorptivity of not less than 95%, used to strongly absorb the remaining visible long-wavelength and near-infrared energy and suppress penetration escape.

[0014] Furthermore, the thickness of each layer of quartz glass substrate is 3-5mm, and the surface of the quartz glass substrate can be processed with structures such as fins, grooves, or slots to disrupt the boundary layer of airflow and multiply the effective heat exchange area. The multilayer spectrally selective absorption quartz glass plate array, through the aforementioned spectral selectivity and semi-transparent absorption characteristics and the energy matching and regulation of the multi-plate array, enables the incident solar energy to be distributed and absorbed multiple times in the depth direction of the cavity. Among them, the ultraviolet absorption layer absorbs about 20% of the incident energy, the visible light absorption layer absorbs about 50% of the incident energy, and the infrared cutoff absorption layer absorbs about 30% of the incident energy, thereby forming a multi-level temperature field in the depth direction of the cavity and achieving volume absorption. This allows the high-temperature zone to be precisely arranged inside the absorber and, combined with a thermal shielding mechanism, reduces heat loss on the front-end light-receiving outer surface.

[0015] Furthermore, the sealed cavity is a non-pressure-bearing structure, providing a closed space for light reception and heat exchange for the multilayer spectrally selective absorbing quartz glass plate array and the air conduction channel, with an output air temperature range of 500℃-1200℃. The cavity is composed of a front light-transmitting window and a rear shell sealed together. The front light-transmitting window is made of high-purity quartz glass, used to allow solar radiation energy flow to pass through into the cavity and isolate the external environment. The rear shell is made of high-temperature resistant metal alloy or silicon carbide ceramic, and its inner wall surface is covered with a high-reflectivity liner, preferably a ceramic-based reflective coating or a metal mirror coating, to maintain high reflectivity in the near-infrared to mid-infrared band, thereby directionally reflecting the remaining radiation energy transmitted through the multilayer spectrally selective absorbing quartz glass plate array back to the heat-absorbing body region for secondary absorption, reducing energy escape and further suppressing the cavity's external radiation heat loss.

[0016] Furthermore, the airflow within the air guide channel is designed as a cross-flow impact type, meaning the guide holes of the upper-level quartz glass plate face the surface of the lower-level quartz glass plate, enhancing impact heat transfer. The airflow within the air guide channel is designed as a composite flow mode combining cross-flow impact and multi-pass deflection.

[0017] Furthermore, the insulation layer is made of microporous insulation material with a thermal conductivity of no more than 0.03 W / (m·K) at room temperature and still controllable within 0.05 W / (m·K) above 800℃. The composite microporous insulation material selected possesses excellent high-temperature stability and compressive strength, with a long-term operating temperature exceeding 1200℃, and can be customized to fit the surface morphology of the cavity. The insulation layer tightly covers the outer wall of the sealed cavity, except for the light-transmitting window, effectively preventing the heat from the high-pressure hot air inside the cavity from diffusing to the external environment by reducing heat loss from the wall surface.

[0018] Furthermore, the support structure is made of high-temperature resistant, low-thermal-conductivity materials, preferably alumina ceramics, mullite ceramics, alumina silicate ceramics, or silicon carbide ceramics, and can be processed into frame-type support frames, support beams, limiting blocks, or lattice support columns, depending on the cavity structure. The support structure possesses good high-temperature dimensional stability and creep resistance, with a long-term operating temperature exceeding 1000℃. Thermal insulation pads or small-contact-area supports can be installed at the contact points with the quartz glass to reduce the thermal bridging effect. The support structure is arranged inside the sealed cavity and connected to the inner wall of the cavity, used for positioning, fixing, and spacing control of the multilayer spectrally selective absorption quartz glass plate array, ensuring the stability of the airflow channel height and cross-sectional dimensions, thereby maintaining the stability and repeatability of airflow organization and heat transfer performance.

[0019] Beneficial effects:

[0020] (1) This invention utilizes the spectral selectivity of modified quartz glass to achieve multi-spectral heat absorption, causing the incident solar radiation energy flow to be deposited in stages along the depth direction of the cavity and converted into heat energy in a volumetric manner. This creates a temperature field with a lower surface temperature and a higher internal temperature of the heat absorber, thereby significantly reducing the contribution of the light-receiving outer surface temperature and the equivalent emissivity, and suppressing the heat absorption at high temperatures. Increased radiative heat loss improves the effective absorption efficiency in the high-temperature section and the overall thermal efficiency.

[0021] (2) The present invention arranges the high temperature zone inside the cavity through volume absorption, and the low temperature quartz glass layer at the front end and the light-transmitting window form a low temperature radiation barrier, reducing the intensity of external radiation and convection heat transfer and reducing the proportion of heat loss on the outer surface; when the outlet temperature is raised to 800°C or even higher, it can still maintain a high photothermal conversion efficiency, avoiding the rapid decline in efficiency of traditional surface absorption structures as the temperature rises.

[0022] (3) The present invention forms a multi-stage temperature difference heat exchange process that matches the direction of solar radiation energy flow, so that the temperature rise of the air along the process is coordinated with the temperature level of each absorption layer increasing along the depth: the cold air preferentially exchanges heat with the low temperature layer and suppresses the heat loss at the front end, and the heated air then exchanges heat with the high temperature layer in a high-efficiency manner, thereby improving the average effective heat exchange temperature difference and the utilization rate of heat exchange driving force, reducing the peak temperature of the heat absorber required to achieve the same outlet temperature, further reducing radiation and convection heat loss and improving the overall thermal efficiency.

[0023] (4) The light-transmitting window used in this invention mainly undertakes the functions of sealing and transmission without directly bearing the strong heat absorption load, thereby reducing the window temperature rise and thermal stress level, reducing the additional energy consumption and shading loss caused by window cooling or structural reinforcement, which is conducive to improving the net thermal efficiency of the system and enhancing long-term operational reliability.

[0024] (5) The heat-absorbing core of the present invention uses quartz glass as the substrate and adopts a compatible inorganic oxide film layer and SiC / high temperature resistant ceramic absorption layer system. The thermal expansion matching of each layer material is good, which can reduce the interfacial thermal stress and performance decay under high temperature cycling, maintain the stability of absorption rate, transmittance and reflection characteristics, and make the thermal efficiency not easily decayed during long-term operation.

[0025] (6) The heat-absorbing core structure of the present invention is adjustable and its energy is controllable. It can optimize the material system, film thickness and interlayer spacing of each absorption layer according to the actual solar spectrum distribution, concentration ratio and target outlet temperature. Moreover, each spectral band can be formed by connecting one or more quartz glass plates with enhanced heat exchange structure to form a sub-array. The number of quartz glass plates in a specific band can be flexibly increased or decreased according to the requirements of different operating conditions, and the energy matching relationship can be precisely adjusted to achieve on-demand customization of the energy deposition depth and multi-level temperature field distribution inside the cavity and the design of minimizing heat loss. Better comprehensive thermal efficiency can be obtained under different operating conditions.

[0026] (7) The present invention has excellent heat dissipation and heat insulation performance. It utilizes the high absorption and high reflection characteristics of the relatively low temperature quartz glass plate and light-transmitting window on the outer layer to form a heat radiation barrier against the secondary heat radiation emitted outward from the high temperature core area inside, fundamentally blocking the heat loss from the inside to the outside, and realizing efficient heat absorption and heat insulation integration. Attached Figure Description

[0027] Figure 1 This is a side view of a multi-layer modified quartz glass-based spectroscopic air receiver for solar thermal power generation according to the present invention.

[0028] Figure 2 A schematic diagram of a parallel structure of multiple quartz glass plates in the same spectral absorption band in a multilayer spectral selective absorption quartz glass plate.

[0029] Figure 3 The images show side views of a single quartz glass plate; the left image shows a side view of a single quartz glass plate with scratches; the right image shows a side view of a single quartz glass plate with fins.

[0030] Figure 4 Top view of a multilayer modified quartz glass cylindrical solar thermal power generation split-spectrum air receiver;

[0031] Figure 5 Cross-sectional view of a multi-layer modified quartz glass cylindrical solar thermal power generation split-spectrum air receiver;

[0032] The attached diagram is labeled as follows: 1. Solar radiation energy flow; 2. Sealed cavity; 3. Light-transmitting window; 4. Multilayer spectrally selective absorption quartz glass plate array; 4-1. Ultraviolet absorption layer; 4-2. Visible light absorption layer; 4-3. Infrared cut-off absorption layer; 5. Air guide channel; 6. Cold air inlet; 7. Hot air outlet; 8. Thermal insulation layer; 9. Support structure; 10. Guide hole. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0034] like Figure 1As shown, the solar thermal power generation spectroscopic air absorber based on multilayer modified quartz glass in this embodiment adopts a cavity form. The cavity is planar and mainly consists of a sealed cavity 2, a light-transmitting window 3, a multilayer spectroscopic selective absorption quartz glass plate array 4, an air guiding channel 5, a cold air inlet 6, a hot air outlet 7, a heat insulation layer 8, a supporting structure 9, and a guide hole 10.

[0035] The sealed cavity 2 constitutes the main support structure of the spectroscopic air absorber for solar thermal power generation, and a light-transmitting window 3 is airtightly connected to its front opening. The light-transmitting window 3 is made of high-purity quartz glass, which has excellent high-temperature resistance and full-spectrum transmittance. It is used to seal the internal space of the cavity and serve as a channel for solar radiation energy flow into the cavity. At the same time, due to the inherent physical properties of quartz material, the light-transmitting window 3 has radiation shielding and heat dissipation functions, effectively preventing the loss of internal heat to the external environment.

[0036] A multilayer spectrally selective absorbing quartz glass plate array 4 is encapsulated inside a sealed cavity 2, arranged sequentially at intervals along the incident direction of solar radiation energy flow 1. From front to back, it includes an ultraviolet absorption layer 4-1, a visible light absorption layer 4-2, and an infrared cutoff absorption layer 4-3, thus forming a heat-absorbing core. The ultraviolet absorption layer 4-1, the visible light absorption layer 4-2, and the infrared cutoff absorption layer 4-3 are all formed of quartz glass plates.

[0037] Preferably, based on the design energy distribution and heat exchange requirements, each absorption layer can be composed of a single or multiple quartz glass plates of different thicknesses with microstructures such as fins and grooves on their surfaces, forming a sub-array.

[0038] Preferably, each layer of quartz glass includes a quartz glass substrate and a spectrally selective absorption film formed on its surface. The thickness of the quartz glass substrate is 3 to 5 mm, and the film can withstand operating temperatures above 800°C. The ultraviolet absorption layer 4-1 is a composite absorption structure constructed on the quartz glass substrate, including CeO2 and TiO2-based inorganic oxide short-wave absorption films formed on the substrate surface and / or CeO2 and TiO2 absorption components introduced into the quartz glass substrate. The cutoff wavelength is approximately 500 nm, with an average absorptivity greater than 85% in the 300 to 500 nm band and an average transmittance greater than 90% in the 500 to 2500 nm band. It is used to preferentially intercept ultraviolet radiation from incident solar radiation and convert it into heat energy. Simultaneously, the relatively low-temperature ultraviolet absorption layer 4-1 at the front end utilizes the characteristics of the quartz substrate to absorb and reflect long-wave thermal radiation emitted outward from the internal high-temperature region, blocking secondary thermal radiation and suppressing radiative heat dissipation from the cavity. The visible light absorption layer 4-2 is a composite absorption structure constructed on a quartz glass substrate, including a high-temperature resistant all-oxide semi-transparent absorption film formed on the surface of the substrate and / or a metal oxide absorption component introduced inside the quartz glass substrate. The all-oxide semi-transparent absorption film is selected from one or more of chromium oxide, iron oxide, cobalt oxide, nickel oxide or manganese oxide and their composite systems, and can be combined with an alumina, silicon dioxide or zirconium oxide dielectric layer for spectral modulation. Its full-spectrum average absorptivity is 45% to 55%, and its full-spectrum average transmittance is 30% to 35%. It focuses on absorbing the 500 to 1100 nm wavelength band to absorb most of the visible light energy in solar radiation and convert it into heat energy, while maintaining moderate transmission so that the remaining radiation energy can continue to be transmitted to the deeper layers. The infrared cutoff absorption layer 4-3 is a composite absorption structure built on a quartz glass substrate, including a SiC high-temperature absorption layer or a black high-temperature resistant ceramic absorption coating formed on the surface of the substrate and / or an infrared absorption component introduced inside the quartz glass substrate. The full-spectrum absorption rate is not less than 95%, and the transmittance is close to zero. It is used to completely absorb the remaining visible light long-wavelength and near-infrared energy that penetrates the first two layers and convert it into heat energy, build a high-temperature zone inside the cavity and suppress the penetration and escape of radiation energy.

[0039] The airflow channel 5 is composed of the gaps between the aforementioned quartz glass plates and staggered guide holes 10 formed on the surface of the quartz glass plates. The guide holes 10 on adjacent quartz glass plates are staggered, with the upper-level guide hole 10 facing the solid area of ​​the lower-level quartz glass plate. This structure guides the airflow to form a composite flow pattern combining cross-flow impact and multi-pass deflection, allowing the airflow passing through the guide holes 10 to directly impact the lower-level quartz glass plate with surface microstructures such as fins, grooves, or slots, forming an S-shaped serpentine deflection path between the array of multiple quartz glass plates. The spacing between adjacent quartz glass plates and the diameter of the guide holes are designed according to the airflow field parameters to disrupt the thermal boundary layer, extend the airflow heat transfer path and residence time, and enhance local impact convection heat transfer, while controlling flow resistance and ensuring stable flow.

[0040] The insulation layer 8 tightly covers the outer wall of the sealed cavity 2, except for the light-transmitting window 3, to reduce heat loss from the cavity to the environment, reduce surface convection and radiation heat dissipation, and ensure the overall thermal efficiency of the absorber.

[0041] A support structure 9 is disposed inside the sealed cavity 2 to position and fix the multilayer spectrally selective absorption quartz glass plate array 4, ensuring stable spacing between the planar quartz glass plates and forming the airflow channels 5 as required by the design. The support structure 9 is preferably made of a high-temperature resistant, low-thermal-conductivity material that matches the thermal expansion of the quartz glass. It is a lattice-type support column, distributed along the circumference of the plate array and the length of the cavity, to limit the normal displacement and in-plane slippage of the quartz glass plates, suppress vibration and warping during operation, thereby ensuring consistent flow channel height, stable flow organization, and repeatable heat transfer performance. The contact area between the support structure 9 and the quartz glass plates preferably has a small contact area or is equipped with thermal insulation pads to reduce solid-conducting thermal bridges and minimize disturbance to the heat absorption temperature field.

[0042] The working process of this invention is as follows: During operation, the solar radiation energy flow 1 from the heliostat field enters the cavity through the light-transmitting window 3 of the absorber. The solar radiation energy flow 1 is not absorbed all at once on the surface of the absorber, but is absorbed in stages according to wavelength in the multilayer spectrally selective absorbing quartz glass plate array 4 and deposited along the depth direction. The ultraviolet radiation is first absorbed by the outermost ultraviolet absorption layer 4-1 and converted into heat energy. The transmitted visible light penetrates further and is absorbed by the visible light absorption layer 4-2. The remaining near-infrared energy finally reaches the infrared cutoff absorption layer 4-3 and is strongly absorbed. At this time, a temperature gradient is formed inside the heat-absorbing core with "low temperature at both ends and high temperature in the middle". During heat dissipation, the light-transmitting window 3 and the ultraviolet absorption layer 4-1, which are in a relatively low temperature state on the outside, utilize the physical property of the quartz substrate being opaque to long-wave thermal radiation to effectively absorb, reflect and re-intercept the secondary long-wave thermal radiation emitted outward from the high-temperature area in the middle into the cavity, greatly reducing radial outward radiative heat dissipation. Meanwhile, cold air enters the air guide channel 5 through the cold air inlet 6, and flows sequentially through each layer along the staggered flow impact and multi-pass deflection path formed by the fan or system pressure difference. The cold air first exchanges heat with the relatively low-temperature visible light absorption layer 4-2 and infrared cutoff absorption layer 4-3 for preheating, and then enters the core area to further heat up by enhancing heat exchange with the high-temperature visible light absorption layer 4-2. After being heated to the target temperature, it is discharged from the hot air outlet 7. This multi-stage temperature difference heat exchange mode, combined with the blocking effect of the light-transmitting window 3 and the front quartz glass plate on long-wave thermal radiation, as well as the insulation effect of the outer insulation layer 8, reduces the overall heat loss of the absorber to the external environment, and achieves high-temperature air output.

[0043] like Figure 2 As shown, multiple quartz glass plates are arranged sequentially at intervals along the direction of solar radiation incidence, forming a plate array structure. The quartz glass plates are basically parallel and have several guide holes 10 on their surfaces. The multi-layer quartz glass plates are fixedly connected to the inner wall of the cavity through support structures at the upper and lower ends. The support structures can be made of high-temperature resistant metal or ceramic materials and have radial positioning ribs to achieve positioning and gap control of each layer of quartz glass plates. The edges of each quartz glass plate are limited and fixed by high-temperature resistant fasteners, with reserved thermal expansion gaps and flexible sealing / buffer gaskets to adapt to thermal stress deformation under high-temperature conditions, ensuring structural stability and sealing.

[0044] like Figure 3 The images shown are side views of a single quartz glass plate; the left image is a side view of a single quartz glass plate with scratches; the right image is a side view of a single quartz glass plate with fins.

[0045] Embodiment 2 of the present invention is as follows Figure 4 , Figure 5The image shows a multi-layer modified quartz glass-based spectrally selective cylindrical air receiver for solar thermal power generation. The receiver cavity structure in this embodiment is cylindrical, suitable for applications such as tower receivers with circumferentially distributed light spots. The receiver mainly includes a sealed cavity 2, a light-transmitting window 3, a multi-layer spectrally selective absorbing quartz glass array 4, an airflow channel 5, a cold air inlet 6, a hot air outlet 7, an insulation layer 8, and a supporting structure 9.

[0046] In this embodiment, the incident direction of the solar radiation energy flow 1 is radial, therefore the multi-stage absorption is achieved sequentially from the outside to the inside radially. The light-transmitting window 3 is a cylindrical quartz glass tube, forming the light-receiving surface of the heat absorber. The sealed cavity 2 is composed of the light-transmitting window 3 and upper and lower end cover plates, forming an airtight connection. The cavity is provided with an annular mounting flange at the connection, and the upper and lower ends of the light-transmitting window 3 are respectively provided with mounting edges or thickened sections, and the two are coaxially positioned and reliably sealed and fixed by flange docking. The multi-layer spectrally selective absorption quartz glass plate array 4 is composed of three layers of concentric cylindrical quartz glass plates, and each layer of quartz glass plates and the light-transmitting window 3 are arranged concentrically in the radial direction. According to the radial energy attenuation characteristics and temperature field distribution requirements, the ultraviolet absorption layer 4-1, the visible light absorption layer 4-2, and the infrared cutoff absorption layer 4-3 are distributed sequentially from the outside to the inside. Each layer can be composed of a single layer or multiple layers of concentric quartz cylinders with surface microstructures stacked to form a sub-array, forming a heat-absorbing core with radially spectrally multi-stage absorption and deep deposition. Each layer of quartz glass includes a quartz glass substrate and a spectrally selective absorption structure built thereon. The absorption structure includes a spectrally selective absorption film layer formed on the surface of the substrate and / or corresponding absorption components introduced into the quartz glass substrate. The thickness of the quartz glass substrate is preferably 3 to 5 mm, and the film layer can withstand operating temperatures above 800°C. Among them, the outermost ultraviolet absorption layer 4-1 is a composite absorption structure built on the quartz glass substrate, including CeO2 and TiO2-based inorganic oxide short-wave absorption films formed on the surface and / or CeO2 and TiO2 absorption components introduced into the quartz glass substrate. Its cutoff wavelength is about 500 nm, which is used to preferentially absorb ultraviolet and some short-wave visible radiation and convert it into heat energy. At the same time, the relatively low-temperature ultraviolet absorption layer 4-1 cooperates with the outer quartz light-transmitting window 3 to block the secondary heat radiation emitted outward from the internal high-temperature area by utilizing the absorption and reflection characteristics of the quartz substrate for long-wave thermal radiation, thus cutting off the radial outward radiation heat dissipation path. The intermediate visible light absorption layer 4-2 is a composite absorption structure built on a quartz glass substrate, including a high-temperature resistant, semi-transparent oxide absorption film formed on the surface and / or a metal oxide absorption component introduced into the quartz glass substrate. The semi-transparent oxide absorption film is selected from one or more of chromium oxide, iron oxide, cobalt oxide, nickel oxide, or manganese oxide and their composite systems, and can be combined with an alumina, silicon dioxide, or zirconium oxide dielectric layer for spectral modulation. It is used to absorb the main energy in the visible light band while retaining a certain amount of transmission to achieve continuous deposition in the radial depth. The innermost infrared cutoff absorption layer 4-3 is a composite absorption structure built on a quartz glass substrate, including a SiC high-temperature absorption layer or a black high-temperature resistant ceramic absorption coating formed on the surface and / or an infrared absorption component introduced into the quartz glass substrate. It is used to strongly absorb the remaining long-wavelength visible light and near-infrared energy that has penetrated the first two layers.

[0047] Each layer of quartz glass plates is equipped with circumferential and axial flow channels to construct airflow channels 5. Specifically, the ultraviolet absorption layer 4-1 has circumferential flow channels symmetrically positioned on both sides of the horizontal centerline; the visible light absorption layer 4-2 has circumferential flow channels symmetrically positioned on both sides of the vertical centerline; and the infrared cutoff absorption layer 4-3 has circumferential flow channels symmetrically positioned on both sides of the horizontal centerline, thereby forming zonal flow and turbulence to enhance heat transfer in the circumferential direction. When any of the above absorption layers is composed of multiple concentric quartz cylinders stacked to form a sub-array, the circumferential flow channels on adjacent quartz cylinders in the sub-array are also arranged according to the staggered arrangement principle, that is, the flow channels on adjacent cylinders are alternately opened along the horizontal and vertical centerlines, or staggered at a specific circumferential angle; so that the airflow passing through the upper-level flow channel directly impacts the solid area of ​​the lower-level quartz cylinder, thereby maintaining a composite flow mode of cross-flow impact and S-shaped multi-pass deflection within the sub-array and between each main absorption layer. An axially connected gap guide channel is provided between the upper and lower ends of each layer of quartz glass plates, allowing airflow to flow in the axial direction and couple with the circumferential flow, thereby connecting the heat exchange areas of each layer and improving heat exchange uniformity. The air guide channel 5 is composed of concentric radial gaps between each layer of quartz glass plates (including each single layer of quartz glass plates in the sub-array), circumferential guide holes, and axially connected flow channels. Its gap size and guide hole distribution can be optimized according to the target flow rate, pressure drop, and heat exchange intensity requirements, so as to control flow resistance and ensure stable operation while breaking the thermal boundary layer and enhancing local impact convection heat transfer.

[0048] The cold air inlet 6 is located at a vertically symmetrical position on the side wall of the absorber and near the cylindrical axis, while the hot air outlet 7 is located at half the radius of the axial end face of the cylindrical cavity, forming a heat exchange organization mode that matches the radial multi-level temperature field. This allows the cold air to preferentially enter the relatively low temperature region and gradually exchange heat with the internal high temperature region before being discharged.

[0049] The insulation layer 8 covers the upper and lower surfaces of the sealed cavity 2 to reduce heat loss from the cavity to the environment, suppress convection and radiation heat dissipation on the surface of the absorber, and ensure the overall efficiency of the absorber.

[0050] A support structure 9 is disposed inside the sealed cavity 2 to position and fix the multilayer spectrally selective absorption quartz glass plate array 4, ensuring stable spacing between the quartz glass plates and forming the designed airflow channel 5. The support structure 9 is preferably made of a material that is resistant to high temperatures, has low thermal conductivity, and matches the thermal expansion of the quartz glass. It can be in the form of a ring-shaped support frame, circumferential support ribs, or a lattice-type support column, and is distributed along the circumferential and axial directions to limit the radial and axial displacement of the quartz glass plates, suppress vibration and warping during operation, thereby ensuring consistent airflow channel dimensions, stable flow organization, and repeatable heat transfer performance. The contact area between the support structure 9 and the quartz glass plates preferably has a small contact area to reduce solid thermal bridges and minimize disturbance to the heat absorption temperature field.

[0051] The working process of Embodiment 2 of the present invention is as follows: During operation, the circumferentially converged solar radiation energy flow 1 from the heliostat field enters the cavity through the cylindrical light-transmitting window 3. The solar radiation penetrates radially sequentially through the ultraviolet absorption layer 4-1, the visible light absorption layer 4-2, and the infrared cutoff absorption layer 4-3, which are composed of single or multiple layers of nested quartz cylinders, achieving graded absorption by wavelength and radial depth volumetric deposition. The ultraviolet energy is mainly captured and converted into thermal energy by the outermost ultraviolet absorption layer 4-1. The visible light energy is partially absorbed by the middle visible light absorption layer 4-2, and the remaining near-infrared energy is strongly absorbed and converted into thermal energy by the innermost infrared cutoff absorption layer 4-3. At this point, a temperature distribution that rises and then falls radially from the outside in forms a high-temperature core region in the middle of the heat-absorbing core. During heat dissipation, the light-transmitting window 3 and the ultraviolet absorption layer 4-1, which are at a relatively low temperature on the outside, utilize the physical property of the quartz substrate being opaque to long-wave thermal radiation to effectively absorb, reflect, and re-intercept the secondary long-wave thermal radiation emitted outward from the high-temperature region in the middle, significantly reducing radial outward radiation heat dissipation. Cold air enters the air guide channel 5 through the cold air inlet 6 and flows circumferentially and axially through the staggered guide holes, radial gaps between plates, and axial through-flow channels driven by the fan or system pressure difference, forming cross-flow impact and deflection paths. The cold air first exchanges heat with the relatively low-temperature ultraviolet absorption layer 4-1 on the outside or the infrared cut-off absorption layer 4-3 on the inner layer and is preheated. Then, it exchanges heat further with the visible light absorption layer 4-2 in the middle and is gradually heated to the target temperature before being discharged from the hot air outlet 7, realizing efficient solar thermal conversion and high-temperature air output.

[0052] In summary, this invention constructs a composite absorption structure on a quartz glass substrate, comprising a surface spectrally selective absorption film and / or matrix-doped absorption components. The heat absorber is designed as an array of quartz glass plates along the optical path, achieving deep spatial separation and stepped absorption of the solar spectrum, effectively locking the high-temperature region within the absorber cavity. Simultaneously, utilizing the strong absorption and reflection characteristics of the outer low-temperature quartz glass plate on the long-wave thermal radiation emitted from the internal high-temperature region, a radiation barrier is constructed, significantly suppressing heat loss from the front end to the external environment. In this structure, air is forced to flow between layers and is progressively heated by quartz glass plates of different temperatures, achieving efficient integration of heat absorption and insulation.

[0053] Compared to single-material volumetric heat absorbers, this invention arranges an ultraviolet absorption layer, a visible light absorption layer, and an infrared cutoff absorption layer sequentially along the direction of solar radiation energy inflow. Each spectral absorption band can be formed by combining multiple quartz glass plates to create a sub-array, allowing photons of different energies to be precisely captured at different depths within the heat absorber. The multi-plate series design allows for flexible adjustment of the energy matching relationship based on the actual energy distribution characteristics of the solar spectrum, by increasing or decreasing the number of quartz glass plates for specific wavelengths, thus achieving on-demand customization of the internal temperature field distribution. This design enables the internal temperature of the heat absorber to be higher than the surface temperature, forming an ideal "hot center, cold edge" temperature field. The low-temperature front and rear surfaces and the light-transmitting window, thanks to the strong absorption and reflection characteristics of quartz glass for long-wave thermal radiation, naturally form a physical barrier against secondary thermal radiation emitted outward from the high-temperature core area, significantly reducing radiative heat loss to the environment, while the high-temperature middle section can heat the air to a relatively high temperature. Furthermore, by using quartz glass as the substrate and adding micro or macro structures such as fins and grooves to its surface to multiply the effective heat exchange area, combined with an extended interlayer cross-flow heat exchange design constructed with multiple plates, including impingement jet heat exchange or multi-pass serpentine reflux heat exchange in the same temperature range, not only is the residence time of air and the intensity of gas-solid convection heat exchange significantly increased, but the problems of high flow resistance and easy brittleness of traditional porous ceramics are also completely solved.

[0054] 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 spectroscopic air receiver for solar thermal power generation based on multilayer modified quartz glass, characterized in that, The absorber comprises a sealed cavity, a light-transmitting window, a multi-layer spectrally selective absorbing quartz glass plate array, an airflow channel, a cold air inlet, a hot air outlet, an insulation layer, and a supporting structure. The overall layout of the absorber, from the outside in, consists of: an insulation layer wrapped around the outer wall of the cavity, a supporting structure, a sealed cavity, and a light-transmitting window. It also includes a multi-layer spectrally selective absorbing quartz glass plate array encapsulated within the cavity. The multi-layer spectrally selective absorbing quartz glass plate array is arranged sequentially at intervals along the direction of solar radiation energy flow, dividing the internal space of the sealed cavity. The airflow channel is formed by the gaps between adjacent quartz glass plates in the multi-layer spectrally selective absorbing quartz glass plate array and the staggered opening structure of the quartz glass plates themselves, allowing air to form a multi-pass flow path between the multiple quartz glass plates and a fluid path connecting the cold air inlet to the hot air outlet. Solar radiation energy flows through the light-transmitting window into the cavity and irradiates the multi-layer spectrally selective absorbing quartz glass plate array. Working air enters through the cold air inlet, is forced to flow through the airflow channel, is heated step-by-step by the quartz glass plates with different temperature gradients, and is discharged through the hot air outlet.

2. The spectral air absorber for solar thermal power generation based on multilayer modified quartz glass according to claim 1, characterized in that, The multilayer spectrally selective absorption quartz glass plate array comprises, in sequence along the direction of solar radiation energy inflow: The ultraviolet absorption layer, located at the front of the array, is composed of one or more ultraviolet absorbing quartz glass plates. It is used to preferentially absorb the ultraviolet band in the solar spectrum, while blocking the thermal radiation emitted outward by the high-temperature layer behind it. The visible light absorption layer, located behind the ultraviolet absorption layer, is composed of one or more visible light absorbing quartz glass plates and is used to absorb the visible light band in the solar spectrum and prevent the leakage of internal high-temperature heat radiation. An infrared cutoff absorption layer, located at the end of the array, consists of one or more infrared cutoff quartz glass plates. It is used to absorb the remaining near-infrared band and the thermal radiation from the front-end layers after they are heated.

3. A spectroscopic air absorber for solar thermal power generation based on multilayer modified quartz glass according to claim 2, characterized in that, The ultraviolet absorption layer, visible light absorption layer, and infrared cutoff absorption layer maintain a preset distance from each other, as do the multiple quartz glass plates within each band layer. Furthermore, the surface of each quartz glass plate substrate is processed with microstructures such as fins, grooves, or slots, thereby forming a multi-level temperature field within the cavity.

4. A spectroscopic air absorber for solar thermal power generation based on multilayer modified quartz glass according to claim 2, characterized in that, The ultraviolet absorption layer is a cerium dioxide and titanium dioxide-based inorganic oxide short-wave absorption film disposed on the surface of the quartz glass substrate, and / or an ultraviolet absorption component formed by introducing cerium dioxide and titanium dioxide into the quartz glass substrate; the visible light absorption layer is a high-temperature resistant, fully oxide semi-transparent absorption film disposed on the surface of the quartz glass substrate, wherein the fully oxide semi-transparent absorption film is selected from one or more of chromium oxide, iron oxide, cobalt oxide, nickel oxide, or manganese oxide, and may include an alumina, silicon dioxide, or zirconium oxide dielectric layer for spectral modulation, and / or the above-mentioned metal oxides are introduced into the quartz glass substrate to form a visible light absorption component; the infrared cutoff absorption layer is a silicon carbide absorption layer or a black high-temperature resistant ceramic absorption coating disposed on the surface of the quartz glass substrate, and / or an infrared absorption component is introduced into the quartz glass substrate.

5. A spectroscopic air receiver for solar thermal power generation based on multilayer modified quartz glass according to claim 2, characterized in that: The thickness of the three-layer quartz glass substrate is 3-5 mm; the cutoff wavelength of the ultraviolet absorption layer is 500 nm; the average absorption rate of the visible light absorption layer is 45%-55% and the average transmittance of the visible light absorption layer is 30%-35%.

6. A spectroscopic air receiver for solar thermal power generation based on multilayer modified quartz glass according to claim 5, characterized in that: The infrared cutoff absorption layer has a full-spectrum absorption rate greater than or equal to 95%; the multi-layer spectrally selective absorbing quartz glass plate array distributes and absorbs incident energy in multiple levels along the direction of solar radiation energy flow, with the ultraviolet absorption layer absorbing 20% ​​of the incident energy, the visible light absorption layer absorbing 50% of the incident energy, and the infrared cutoff absorption layer absorbing 30% of the incident energy, so as to form a multi-level temperature field in the depth direction of the cavity and achieve volume absorption.

7. A spectroscopic air receiver for solar thermal power generation based on multilayer modified quartz glass according to claim 1, characterized in that, The specific structure of the air guiding channel is as follows: each layer of the multilayer spectrally selective absorption quartz glass plate array has staggered guiding holes; the guiding holes guide the airflow to vertically impact the surface of the next-level quartz glass plate, forming an impact jet heat exchange structure, and guiding the airflow to serpentine backflow between layers.

8. A spectroscopic air receiver for solar thermal power generation based on multilayer modified quartz glass according to claim 1, characterized in that, The sealed cavity is formed by a front cover plate and a rear shell that are sealed together.

9. A spectroscopic air absorber for solar thermal power generation based on multilayer modified quartz glass according to claim 1, characterized in that, The front cover is made of high-purity quartz glass, which is the light-transmitting window. It is used to withstand the air pressure inside the cavity, transmit the full-band solar spectrum, and prevent the high-temperature radiation from the rear from leaking outward. The other parts except the cover are made of high-temperature resistant metal alloy or silicon carbide ceramic. The inner wall surface of the other parts except the cover is provided with a reflective liner, which is used to reflect the unabsorbed energy transmitted through the multi-layer spectral selective absorption quartz glass plate array back to the quartz glass plate array to achieve secondary absorption.

10. A spectroscopic air receiver for solar thermal power generation based on multilayer modified quartz glass according to claim 1, characterized in that, The arrangement of the cold air inlet and hot air outlet meets the requirements of multi-stage temperature difference matching heat exchange: the cold air inlet is located on the side wall of the sealed cavity, close to the ultraviolet absorption layer and the infrared cutoff absorption layer; the hot air outlet is located in the middle of the sealed cavity, near the visible light absorption layer. The flow direction of the working medium air is generally consistent with the temperature field distribution of the quartz glass plate array, forming a multi-stage heat exchange mode of heat exchange between low-temperature air and low-temperature plate and heat exchange between high-temperature air and high-temperature plate.

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