Spectral frequency division photovoltaic-photothermal device based on optical coupling and double-loop heat collection

Abstract

The present application relates to a kind of spectrum based on optical coupling and double circuit heat collection frequency photovoltaic photothermal device, including parabolic base and the frequency film suspended above it.The center of frequency film is high reflectivity narrow-band infrared reflective film layer, both sides are broadband transmission visible light film layer;Parabolic base bottom is equipped with interval control component, its top end is connected with the long strip contact head extending along focal line, and is supported with frequency film back line contact;Frequency film edge is connected with parabolic base side by edge tensioning mechanism, which includes sliding guide rail, assembly slide and reset spring, slide and guide rail sliding fit, reset spring provides the biasing force away from center.Interval control component drives contact head to lift to lift or release frequency film center, assembly slide slides along guide rail with frequency film thermal expansion and contraction, and the optical coupling gap between frequency film and parabolic base is dynamically adjusted by linkage.The present application can compensate thermal expansion deformation, eliminate the surface distortion caused by multi-point support, and maintain the stability of optical coupling gap.

Description

Technical Field

[0001] This invention relates to the field of high-efficiency comprehensive utilization of solar energy, and in particular to a spectral frequency division photovoltaic thermal device based on optical coupling and dual-loop heat collection. Background Technology

[0002] With the increasingly severe fossil fuel crisis, the efficient utilization of solar energy as a clean and renewable energy source has become a research hotspot in the global energy technology field. In the process of solar photovoltaic utilization, the spectral response range of commercial crystalline silicon photovoltaic cells is mainly concentrated in the visible and near-infrared bands of 380nm-1120nm, while the long-wave infrared radiation (wavelength greater than 1120nm), which accounts for more than 50% of the total solar radiation energy, cannot be effectively converted into photoelectric energy. If this energy is absorbed by the cell, it will be converted into waste heat, leading to a significant increase in the cell's operating temperature. Studies have shown that for every 1°C increase in the temperature of a crystalline silicon cell, its output power decreases by approximately 0.4%-0.5%, and high temperatures accelerate the aging of encapsulation materials, severely restricting the system's photoelectric conversion efficiency and lifespan. To achieve efficient utilization of the full spectrum of solar energy according to its grade, the spectral frequency division concentrated photovoltaic / thermal (CPV / T) technology has emerged. This technology achieves spectral separation and energy cascade utilization in physical space by placing a wavelength-selective frequency-dividing element between the concentrator and the photovoltaic cell. This element transmits visible light and effective near-infrared bands from the solar spectrum to the photovoltaic cell for power generation, while reflecting long-wave infrared bands back to the collector for heat energy. For example, the concentrating full-spectrum photovoltaic-thermal combined system proposed by the Institute of Electrical Engineering, Chinese Academy of Sciences (see CN106160658B, 2016) uses a parabolic concentrator and frequency-dividing film combination structure to achieve preliminary separation of visible light transmission and infrared reflection. Widyolar et al. (2017-2018) reported a spectral frequency-dividing system combining a parabolic trough concentrator with a dichroic filter. Peacock et al. (2022) further studied the SBS-CPV / T collector using a dichroic interference filter, which achieved an optical efficiency of about 77%.

[0003] However, existing spectral frequency division PV-T (Photovoltaic-Thermal) technology has the following technical drawbacks in engineering applications: First, under focusing conditions, a specific optical coupling gap needs to be maintained between the frequency division film and the focusing substrate to suppress Fresnel reflection and total internal reflection losses at the interface. However, flexible frequency division films are prone to wrinkling or loosening due to the mismatch of the material's thermal expansion coefficient in high-temperature focusing environments, leading to optical surface distortion. Currently, rigid multi-point support or edge-rigid fixed mechanical structures are mostly used (such as the steel cable spring compensation structure disclosed in CN201210111236.3). Although such structures can provide basic tension, they cannot adaptively compensate for the film elongation caused by thermal expansion. Moreover, multi-point support is prone to producing a "tent effect" or local wavy deformation on the film surface, making it difficult to maintain sub-millimeter-level optical surface accuracy.

[0004] Secondly, for parabolic concentrators, the central focal region forms a physical shadow area due to the presence of the heat collection tubes, while the two side regions are fully illuminated. Currently, most designs use a uniform film layer, failing to optimize spatial partitioning to account for the differences in optical characteristics between the central shadow area and the two side direct-illuminated areas. This results in extremely low photovoltaic power generation efficiency in the central region and a tendency to generate hot spots, while the infrared energy in the two side regions is not effectively collected, causing a mismatch between spectral utilization efficiency and spatial light field distribution.

[0005] In addition, existing frequency division film support mechanisms lack dynamic control capabilities and cannot actively fine-tune the optical coupling gap between the frequency division film and the substrate according to real-time operating conditions (such as temperature changes and wind load disturbances). This causes the interface optical loss to fluctuate with environmental changes, making it difficult to maintain optimal optical efficiency throughout the entire operating cycle.

[0006] Therefore, there is an urgent need for a flexible frequency division film support and control scheme that can adaptively compensate for thermal expansion deformation, eliminate multi-point support surface distortion, and dynamically maintain the optical coupling gap, so as to achieve high-precision and long-term stable operation of the spectral frequency division PV-T device under concentrated light conditions. Summary of the Invention

[0007] Therefore, it is necessary to provide a spectral frequency division photovoltaic thermal device based on optical coupling and dual-loop heat collection that can adaptively compensate for thermal expansion deformation, eliminate multi-point support surface distortion, and dynamically maintain the optical coupling gap, in order to address the above problems.

[0008] The present invention provides a spectral frequency division photovoltaic thermal device based on optical coupling and dual-loop heat collection, comprising a parabolic substrate and a frequency division film suspended above the parabolic substrate. The frequency division film includes a high reflectivity narrow-band infrared reflective film layer located in the central region and a broadband transmission visible light film layer symmetrically arranged on both sides of the high reflectivity narrow-band infrared reflective film layer. A spacing adjustment component is provided at the bottom center of the parabolic substrate along its focal line direction. A long strip contact head is connected to the top of the spacing adjustment component. The long strip contact head extends longitudinally along the focal line direction to form a line contact support with the back of the frequency division film. At least two opposite edges of the frequency division film are respectively connected to the side of the parabolic substrate through an edge tensioning mechanism. The edge tensioning mechanism includes a sliding guide rail, an assembly slider, and a return spring. The sliding guide rail is fixed to the parabolic substrate, and the assembly slider is slidably engaged with the sliding guide rail. The edge of the frequency division film is fixedly connected to the assembly slider. The return spring is disposed on the side of the assembly slider facing away from the center of the parabolic substrate and is used to provide a biasing force to the assembly slider to make it move away from the center. The spacing adjustment component is configured to drive the elongated contact head to rise and fall, thereby lifting or releasing the central region of the frequency division film. The assembly slider is configured to slide along the sliding guide rail under the biasing force of the reset spring, as the frequency division film expands or contracts, thereby dynamically adjusting the optical coupling gap between the frequency division film and the parabolic substrate.

[0009] In one embodiment, the broadband transmittance visible light film is configured to have high transmittance for light with wavelengths from 380 nm to 1120 nm, and the high reflectivity narrowband infrared reflectance film is configured to have high reflectivity for light with wavelengths greater than 1120 nm. In one embodiment, the top of the elongated contact head has a smooth chamfer or arc surface, and its surface is coated with a low-friction coating or inlaid with wear-resistant strips.

[0010] In one embodiment, the spacing adjustment assembly further includes a frame, a motor, a screw, and a spacing sensor; the motor and the spacing sensor are mounted on the frame, the screw is driven to the output shaft of the motor, and its top end is connected to the elongated contact head; the probe of the spacing sensor is positioned facing the back of the frequency division film.

[0011] In one embodiment, the edge of the frequency divider is fixed to the assembly slider by a clamping structure, the clamping structure including an upper assembly strip and a lower assembly strip, the frequency divider is clamped between the two and locked by a plurality of pre-tightening bolts spaced longitudinally.

[0012] In one embodiment, the bottom of the assembly slider is provided with a guide groove, which slides and engages with the sliding guide rail; the side wall of the assembly slider is provided with a hook structure for hooking the end of the reset spring.

[0013] In one embodiment, driven by the spacing adjustment component, the frequency division film is shaped into a parabolic shape that corresponds to the profile of the parabolic substrate, and a gradient gap is formed between them, wherein the gap corresponding to the high reflectivity narrow-band infrared reflective film layer region is smaller than the gap corresponding to the broadband transmission visible light film layer region.

[0014] In one embodiment, the system further includes a photovoltaic cell module disposed on the inner surface of the parabolic substrate, a heat collection tube disposed at the focal line position of the parabolic substrate, and a dual-loop heat recovery system connecting the photovoltaic cell module and the heat collection tube.

[0015] In one embodiment, the device further includes a control unit configured to receive a detection signal from the spacing sensor and control the motor to drive the elongated contact head to rise and fall, so as to maintain the optical coupling gap within a preset range.

[0016] In one embodiment, the parabolic substrate is part of the building envelope, constituting a building-integrated photovoltaic (BIPV) module.

[0017] The aforementioned spectral frequency division photovoltaic-thermal device based on optical coupling and dual-loop heat collection uses a long strip-shaped contact head extending longitudinally along the focal line to form a line contact support with the back of the frequency division film, replacing the traditional multi-point support method. This effectively avoids the "tent effect" or wavy local deformation on the flexible film surface caused by uneven force at discrete support points, thus ensuring that the central area of ​​the frequency division film can be shaped and maintained into a high-precision parabolic surface conforming to the optical design. Simultaneously, through a tensioning mechanism located at the edge of the frequency division film, consisting of a sliding guide rail, an assembly slider, and a return spring, this scheme achieves purely mechanical passive adaptive compensation for the thermal expansion deformation of the frequency division film: when the frequency division film relaxes due to thermal expansion, the bias force of the return spring pushes the assembly slider outward, automatically tightening the film surface again to eliminate wrinkles; when the frequency division film contracts due to cooling or being lifted at the center, the assembly slider can overcome the spring force and slide inward to make way, preventing damage to the film layer due to stress concentration. The aforementioned linkage design of centerline contact lifting and edge spring slider tensioning together constitutes a dynamic balance system, which enables the optical coupling gap between the frequency division film and the parabolic substrate to be adaptively adjusted according to the real-time state of the film layer (such as thermal expansion and contraction, lifting height), thereby maintaining the optimal gap range that is conducive to suppressing Fresnel reflection loss in a long-term stable manner under complex working conditions. Ultimately, it solves the problems of decreased optical surface accuracy and increased interface light energy loss caused by thermal expansion wrinkles, support deformation and gap instability of flexible frequency division film. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of a spectral frequency division photovoltaic thermal device based on optical coupling and dual-loop heat collection, according to one embodiment. Figure 2 for Figure 1 A sectional view; Figure 3 for Figure 1 A schematic diagram of the jacking state of a frequency-division photovoltaic thermal device; Figure 4 A sectional view of the tensioning mechanism that links the slider and the return spring; Figure 5 A partial schematic diagram of the frequency division membrane structure held between the upper and lower assembly strips; Figure 6 This is a partial schematic diagram of the assembly of the slider and sliding guide rail, and the structure of the return spring hook.

[0020] Figure label: 1. Parabolic substrate; 2. Broadband transmission visible light film layer; 3. Upper mounting strip; 201. High reflectivity narrow band infrared reflective film layer; 301. Preload bolt; 302. Lower mounting strip; 303. Assembly slider; 304. Sliding guide rail; 305. Return spring; 401. Frame; 402. Screw; 405. Motor; 410. Long strip contact head. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on the other component or there may be an intermediate component. When a component is considered to be "connected to" another component, it can be directly connected to the other component or there may be an intermediate component present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used in this specification are for illustrative purposes only and do not represent the only possible implementation.

[0023] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0024] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature and the second feature are in indirect contact through an intermediate medium. Furthermore, "above," "over," and "on top" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0025] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used in this specification includes any and all combinations of one or more of the associated listed items.

[0026] The following is combined Figures 1-6 This invention describes a spectral frequency division photovoltaic thermal device based on optical coupling and dual-loop heat collection.

[0027] like Figure 1 and Figure 2As shown, in one embodiment, a spectral frequency division photovoltaic thermal device based on optical coupling and dual-loop heat collection includes a parabolic substrate 1 and a frequency division film suspended directly above the parabolic substrate 1. The frequency division film includes a high-reflectivity narrow-band infrared reflective film layer located in the central region and broadband transmission visible light film layers symmetrically arranged on both sides of the high-reflectivity narrow-band infrared reflective film layer. The parabolic substrate 1 is made of metal sheet or polymer composite material through a precision molding process. Its inner surface is processed into a high-precision parabolic profile with an opening width of 600mm to 1200mm, a depth of 200mm to 400mm, and a focal length of 150mm to 300mm. The parabolic substrate 1 serves as a high-strength structural support, providing a precise parabolic shaping reference for the frequency division film above. The cross-sectional profile of the parabolic substrate is parabolic, and its mathematical expression is y=x² / 4f, where f is the focal length, so that all light rays incident parallel to its axis of symmetry converge at the focal line after reflection. The frequency division film is suspended directly above the parabolic substrate 1. It is not a single, uniform optical film, but rather a composite film structure with spatially partitioned layers designed according to optical functions. Specifically, it includes two sets of symmetrically arranged broadband visible light transmission film layers 2 and a high-reflectivity narrow-band infrared reflective film layer 201 located at the center between the two sets of broadband visible light transmission film layers 2. The high-reflectivity narrow-band infrared reflective film layer 201 is located directly above the focal line of the parabolic substrate 1, with a width of 80mm to 150mm, extending continuously longitudinally. The broadband visible light transmission film layers 2 on both sides... With a width ranging from 200mm to 400mm and extending continuously along the longitudinal direction, this partitioned arrangement matches the light-gathering characteristics of the parabolic substrate 1. The focal region has a high light-gathering ratio and high energy density, making it suitable for arranging infrared reflective films for heat collection. The light-gathering ratio gradually decreases in the two side regions, making them suitable for arranging visible light transmission films for photovoltaic power generation. This achieves precise separation of the solar spectrum, efficiently guiding visible light to photovoltaic cells while focusing infrared light for the production of high-grade heat energy. This fundamentally solves the contradiction between photovoltaics and photothermal energy in terms of energy bands, realizing full-spectrum cascade utilization. Both the broadband transmission visible light film layer and the high-reflectivity narrowband infrared reflective film layer adopt a multilayer film system design. For example, the required spectral selectivity can be achieved by using TiO2 / SiO2 alternating coating or metal-dielectric composite film processes.

[0028] A spacing adjustment component is provided at the bottom center of the parabolic substrate 1 along its focal line. A long strip-shaped contact head 410 is connected to the top of the spacing adjustment component. The long strip-shaped contact head 410 extends longitudinally along the focal line to form line contact support with the back of the frequency division film. (Refer to...) Figure 3 and Figure 4The spacing adjustment component is positioned directly below the central focal line of the parabolic base 1. Its telescopic rod has a long, strip-shaped contact head 410 extending longitudinally along the focal line of the parabola. The top of this contact head 410 has a rounded chamfer, forming a smooth line contact with the back of the frequency divider diaphragm. This line contact design ensures extremely uniform longitudinal force when the frequency divider diaphragm is lifted upwards to adjust the gap, completely avoiding the wavy deformation and stress concentration damage to the diaphragm surface that are easily caused by traditional multi-point support. The spacing adjustment component includes a portal or rectangular frame securely mounted at the center of the bottom of the parabolic base. A high-precision stepper motor is fixedly installed at the bottom of the frame, and the motor's output shaft is connected to a vertically extending screw. A screw cylinder, precisely fitted to the external thread of the screw, is embedded in the top beam of the frame. The long, strip-shaped contact head is rigidly connected to the top of the screw. To prevent radial deflection of the screw during rotation and lifting, a limiting plate that slides through the limiting ports on both sides of the frame is provided on the side of the motor or screw base, ensuring absolute verticality of the lifting action.

[0029] At least two opposite edges of the frequency divider diaphragm are respectively connected to the sides of the parabolic substrate 1 via an edge tensioning mechanism. The edge tensioning mechanism includes a sliding guide rail 304, an assembly slider 303, and a return spring 305. The sliding guide rail 304 is fixed to the parabolic substrate 1, and the assembly slider 303 is slidably engaged with the sliding guide rail 304. The edge of the frequency divider diaphragm is fixedly connected to the assembly slider 303. The return spring 305 is located on the side of the assembly slider 303 facing away from the center of the parabolic substrate 1, and is used to provide a biasing force to the assembly slider 303, causing it to move away from the center. (Refer to...) Figure 4 and Figure 6In the lateral gradient zone of the inner wall of the parabolic substrate 1, the assembly slider 303 and the sliding guide rail 304 replace the traditional rigid fixing structure. The bottom of the assembly slider 303 is provided with a guide groove, which slides and engages with the sliding guide rail 304. The side wall of the assembly slider 303 is provided with a hook structure for hooking the end of the return spring 305. The return spring 305 is located inside the assembly slider 303. Its normal thrust forces the assembly slider 303 to move away from the center. This innovative slider and spring structure gives the frequency divider diaphragm a strong passive adaptive capability. Among them, the spacing adjustment component is configured to drive the elongated contact head 410 to rise and fall, so as to lift or release the center area of ​​the frequency divider diaphragm. The assembly slider 303 is configured to move with the frequency divider diaphragm under the biasing force of the return spring 305. The expansion or contraction of the frequency divider film causes it to slide along the sliding guide rail 304, thereby dynamically adjusting the optical coupling gap between the frequency divider film and the parabolic substrate 1. When the center spacing adjustment component lifts the frequency divider film upward, the lateral span of the film surface increases. Under the action of film surface tension, the assembly slider 303 compresses the return spring 305 inward and slides towards the center along the sliding guide rail 304. When the temperature decreases and the film surface contracts, the return spring 305 rebounds and pushes the assembly slider 303 outward, automatically compensating for the shrinkage of the film layer and keeping the film surface taut and flat. This achieves sub-millimeter-level precise control of the flexible frequency divider film surface and elimination of thermal expansion wrinkles, and eliminates the total reflection loss of the traditional interface layer. It effectively suppresses Fresnel reflection and total reflection loss under focusing conditions, and significantly improves the light energy transmission efficiency. The passive adaptive process specifically includes: during the lifting and repositioning, the inward pulling force generated by the lateral span contraction of the membrane layer is greater than the preload of the return spring 305, forcing the assembly slider 303 to slide along the guide rail towards the center for mechanical repositioning, thus preventing the membrane from breaking due to stress concentration; during thermal expansion and stretching, the thermal expansion of the membrane layer causes it to relax, and the return spring 305 releases its stored energy, pushing the assembly slider 303 outward, automatically "absorbing" the thermal expansion deformation of the membrane layer, and stretching the membrane layer back to both sides to achieve self-repair of the surface shape.

[0030] The broadband transmission visible light film layer 2 is configured to have high transmittance for light with wavelengths from 380 nm to 1120 nm, and the high reflectivity narrowband infrared reflective film layer 201 is configured to have high reflectivity for light with wavelengths greater than 1120 nm. This spectral configuration matches the spectral response range of commercial crystalline silicon photovoltaic cells. The spectral response range of crystalline silicon photovoltaic cells is mainly concentrated in the visible and near-infrared bands from 380 nm to 1120 nm, while the long-wave infrared radiation, which accounts for more than 50% of the total solar energy, cannot be effectively converted. Through the above-mentioned frequency division design, the visible and near-infrared bands are guided to the photovoltaic cell for photoelectric conversion, and the long-wave infrared radiation is reflected and focused for heat collection, thereby fundamentally achieving precise separation of the solar spectrum and extracting what is needed. The top of the elongated contact head 410 has a smooth chamfer or arc surface, and its surface is coated with a low-friction coating or inlaid with wear-resistant strips, as shown in the reference. Figure 4The top of the elongated contact head 410 has a rounded chamfer, forming a smooth line contact support band with the back of the frequency divider diaphragm. A low-friction coating or embedded wear-resistant slider reduces the coefficient of friction with the back of the frequency divider diaphragm, preventing wear during lifting and adjustment, and ensuring long-term operational reliability and diaphragm integrity. The low-friction coating can be, for example, a Teflon (PTFE) coating, and the wear-resistant slider can be, for example, an ultra-high molecular weight polyethylene (UHMWPE) slider.

[0031] The spacing adjustment assembly also includes a frame 401, a motor 405, a screw 402, and a spacing sensor, as shown in the reference. Figure 3 and Figure 4 The motor 405 and the spacing sensor are mounted on the frame 401. The screw 402 is driven by the output shaft of the motor 405, and its top end is connected to the elongated contact head 410. The probe of the spacing sensor faces the back of the frequency division membrane. The motor 405 drives the screw 402 to rotate, thereby driving the elongated contact head 410 to rise or fall, realizing the lifting or releasing of the central area of ​​the frequency division membrane. The spacing sensor is used to monitor the absolute height and local gap value of the back of the membrane in real time, providing feedback data for the closed-loop control of the gap, thereby realizing the active and precise control of the optical coupling gap. The spacing sensor is a miniature laser displacement sensor or a high-precision capacitive displacement sensor. The edge of the frequency division membrane is fixed to the assembly slider 303 by a clamping structure, which includes an upper assembly strip 3 and a lower assembly strip 302, as shown in the figure. Figure 1 and Figure 5 The frequency divider is clamped between the upper assembly strip 3 and the lower assembly strip 302 and locked in place by a plurality of pre-tightening bolts 301 arranged longitudinally at intervals. Both the upper assembly strip 3 and the lower assembly strip 302 are long strip-shaped components made of aluminum alloy or stainless steel profiles, extending longitudinally, with their length matching the longitudinal dimension of the frequency divider, ranging from 1000mm to 2000mm. The pre-tightening bolts 301 are arranged longitudinally at intervals of 100mm to 200mm. By adjusting the tightening torque of the pre-tightening bolts 301, the initial clamping tension of the frequency divider can be precisely controlled. The lower assembly strip 302 is fixed as a whole on the assembly slider 303, thereby achieving a reliable connection between the edge of the frequency divider and the assembly slider 303.

[0032] The bottom of the assembly slider 303 is provided with a guide groove, which slides and engages with the sliding guide rail 304. The side wall of the assembly slider 303 is provided with a hook structure for hooking the end of the return spring 305. (Refer to...) Figure 6The guide groove at the bottom of the assembly slider 303 forms a sliding engagement with the sliding guide rail 304, ensuring that the assembly slider 303 can only slide slightly laterally. The hook structure on the side wall of the assembly slider 303 is used to hook the end of the return spring 305, so that the return spring 305 can apply a stable bias force to the assembly slider 303. This structure is simple and reliable, and easy to assemble and maintain. The guide groove is inverted U-shaped or enclosing, forming a precise sliding engagement with the sliding guide rail. This design has dual engineering significance: first, it strictly limits the assembly slider to only slide linearly in one dimension laterally; second, it completely locks the assembly slider vertically, preventing it from falling off the guide rail or jumping when subjected to gusts of wind or violent lifting outdoors. Driven by the spacing adjustment component, the frequency division film is shaped into a parabolic shape that corresponds to the contour of the parabolic substrate 1, and a gradient gap is formed between them. The gap corresponding to the high reflectivity narrow-band infrared reflective film layer 201 is smaller than the gap corresponding to the broadband transmission visible light film layer 2. As the elongated contact head 410 lifts the frequency division film upward from the central region, the central region of the frequency division film is lifted to a higher height, while the two side edge regions are lifted to a lower height, thus forming a parabolic shape that corresponds to the contour of the parabolic substrate 1. The gap between the central region and the parabolic substrate 1 is smaller, while the gap between the two side regions and the parabolic substrate 1 is larger. This gradient gap design makes the optical coupling of the central high-energy-density region tighter, reducing interface loss, while the two side low-energy-density regions maintain an appropriate gap, ensuring efficient transmission and conversion of light energy. The specific range of the gradient gap is as follows: at the high reflectivity narrow-band infrared reflective film layer corresponding to the focal line region, the gap is 0.3mm-0.8mm; at the broadband transmission visible light film layer corresponding to the gradient regions on both sides, the gap gradually increases, reaching 2mm-4mm at the edge.

[0033] In one embodiment, the device further includes a photovoltaic cell module disposed on the inner surface of the parabolic substrate 1, a heat collection tube disposed at the focal line position of the parabolic substrate 1, and a dual-loop heat recovery system connecting the photovoltaic cell module and the heat collection tube. The flexible photovoltaic cell module is laid in a conformal manner on the inner surface area of ​​the parabolic substrate 1. The dual-loop heat recovery system includes a low-temperature preheating loop that flows through the back of the photovoltaic cell that is laid in a conformal manner at the bottom of the parabolic substrate 1 to absorb photovoltaic waste heat, and a high-temperature heating loop that flows through the central heat collection tube located at the focal line position of the parabolic substrate 1 to absorb high-density infrared concentrated light energy precisely reflected by the high-reflectivity narrow-band infrared reflective film layer 201. This organically combines low-grade photovoltaic waste heat with high-grade infrared concentrated heat, resulting in high-temperature heat output and high practical value. The overall energy utilization rate of the system far exceeds that of the traditional PV-T system. The specific working process of the dual-loop cascade heat recovery system is as follows: The circulating working fluid (such as water, heat transfer oil or phase change microcapsule suspension) first flows through the microchannel heat dissipation backplate on the back of the photovoltaic cell to absorb photovoltaic waste heat; then, the preheated working fluid is pumped into the central vacuum heat collection tube located at the focal line. The outer wall of the heat collection tube has a selective coating with high absorptivity, and a spiral turbulence core can be set inside to enhance heat exchange. The working fluid absorbs high-density infrared radiation energy here and produces a high-grade heat source. The device also includes a control unit configured to receive detection signals from the gap sensor and control the motor 405 to drive the elongated contact head 410 to rise and fall, maintaining the optical coupling gap within a preset range. The control unit receives real-time monitoring data of the film backside height from the gap sensor and compares it with the preset gap range. When the detected gap value deviates from the preset range, the control unit sends a command to drive the motor 405, causing the screw 402 and the elongated contact head 410 to rise and fall until the gap value returns to the preset range. This achieves closed-loop automatic control of the optical coupling gap. The device can automatically optimize its operating state according to environmental changes, exhibiting strong robustness and suitability for complex and variable operating environments. The control unit can be based on a microcontroller or PLC architecture and can integrate multi-source environmental data for proactive control. In low-cost or grid-connected applications, the motor in the gap control component can be replaced with a high-precision manual adjustment knob. The parabolic substrate 1 is part of the building envelope, constituting a building-integrated photovoltaic (BIPV) and solar thermal (STP) module. This spectral frequency-division BIPV / T device can be applied to building envelopes such as windows, curtain walls, and blinds, forming a BIPV / T module that organically integrates the building with the solar energy utilization system, expanding the application scenarios and market value of the device. The design of the frequency-division film can be customized according to the specific type of the underlying photovoltaic cell (such as amorphous silicon or perovskite cells) and the required heat collection temperature range.

[0034] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0035] The above-described embodiments are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims

1. A spectral frequency division photovoltaic thermal device based on optical coupling and dual-loop heat collection, characterized in that, It includes a parabolic substrate and a frequency division film suspended directly above the parabolic substrate. The frequency division film includes a high reflectivity narrow-band infrared reflective film layer located in the central region and a broadband transmission visible light film layer symmetrically arranged on both sides of the high reflectivity narrow-band infrared reflective film layer. A spacing adjustment component is provided at the bottom center of the parabolic substrate along its focal line direction. A long strip contact head is connected to the top of the spacing adjustment component. The long strip contact head extends longitudinally along the focal line direction to form a line contact support with the back of the frequency division film. At least two opposite edges of the frequency division film are respectively connected to the side of the parabolic substrate through an edge tensioning mechanism. The edge tensioning mechanism includes a sliding guide rail, an assembly slider, and a return spring. The sliding guide rail is fixed to the parabolic substrate, and the assembly slider is slidably engaged with the sliding guide rail. The edge of the frequency division film is fixedly connected to the assembly slider. The return spring is disposed on the side of the assembly slider facing away from the center of the parabolic substrate and is used to provide a biasing force to the assembly slider to make it move away from the center. The spacing adjustment component is configured to drive the elongated contact head to rise and fall, thereby lifting or releasing the central region of the frequency division film. The assembly slider is configured to slide along the sliding guide rail under the biasing force of the reset spring, as the frequency division film expands or contracts, thereby dynamically adjusting the optical coupling gap between the frequency division film and the parabolic substrate.

2. The spectral frequency division photovoltaic thermal device based on optical coupling and dual-loop heat collection according to claim 1, characterized in that, The broadband transmission visible light film is configured to have high transmittance for light with wavelengths from 380 nm to 1120 nm, and the high reflectivity narrowband infrared reflective film is configured to have high reflectivity for light with wavelengths greater than 1120 nm.

3. The spectral frequency division photovoltaic thermal device based on optical coupling and dual-loop heat collection according to claim 1, characterized in that, The top of the elongated contact head has a smooth chamfer or arc surface, and its surface is coated with a low-friction coating or inlaid with wear-resistant strips.

4. The spectral frequency division photovoltaic thermal device based on optical coupling and dual-loop heat collection according to claim 1, characterized in that, The spacing adjustment component also includes a frame, a motor, a screw, and a spacing sensor; the motor and the spacing sensor are mounted on the frame, the screw is driven by the output shaft of the motor, and its top end is connected to the elongated contact head; the probe of the spacing sensor is positioned facing the back of the frequency division film.

5. The spectral frequency division photovoltaic thermal device based on optical coupling and dual-loop heat collection according to claim 1, characterized in that, The edge of the frequency division film is fixed to the assembly slider by a clamping structure, which includes an upper assembly strip and a lower assembly strip. The frequency division film is clamped between the two and locked by a plurality of pre-tightening bolts spaced apart along the longitudinal direction.

6. The spectral frequency division photovoltaic thermal device based on optical coupling and dual-loop heat collection according to claim 1, characterized in that, The bottom of the assembly slider is provided with a guide groove, which slides and engages with the sliding guide rail; the side wall of the assembly slider is provided with a hook structure for hooking the end of the reset spring.

7. The spectral frequency division photovoltaic thermal device based on optical coupling and dual-loop heat collection according to claim 1, characterized in that, Driven by the spacing adjustment component, the frequency division film is shaped into a parabolic shape that corresponds to the contour of the parabolic substrate, and a gradient gap is formed between the two, wherein the gap corresponding to the high reflectivity narrow-band infrared reflective film layer region is smaller than the gap corresponding to the broadband transmission visible light film layer region.

8. The spectral frequency division photovoltaic thermal device based on optical coupling and dual-loop heat collection according to claim 1, characterized in that, It also includes a photovoltaic cell module disposed on the inner surface of the parabolic substrate, a heat collection tube disposed at the focal line position of the parabolic substrate, and a dual-loop heat recovery system connecting the photovoltaic cell module and the heat collection tube.

9. The spectral frequency division photovoltaic thermal device based on optical coupling and dual-loop heat collection according to claim 4, characterized in that, The device also includes a control unit configured to receive the detection signal from the spacing sensor and control the motor to drive the elongated contact head to rise and fall, so as to maintain the optical coupling gap within a preset range.

10. The spectral frequency division photovoltaic thermal device based on optical coupling and dual-loop heat collection according to any one of claims 1 to 9, characterized in that, The parabolic substrate is part of the building envelope and constitutes a photovoltaic-thermal building integrated module.

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