An all-in-one liquid-filled spectral filtering condenser based on total reflection

Abstract

The application discloses a kind of integral liquid filling spectral filtering concentrators based on total reflection, including sealed shell, internal total reflection wall surface and filling in the cavity of spectral selective absorption liquid. Through the oblique design of total reflection wall surface, light occurs total reflection at solid-liquid interface, realizes low-loss concentration;Liquid medium selectively absorbs photovoltaic non-response waveband and converts into heat energy, while cooling battery. Multiple concentrating units can be cascaded into linear and point-type concentrator array, realizing high-multiple concentration. The application solves the technical problems of high optical loss, insufficient spectral utilization, functional separation and complex structure in solar concentration system, realizes the integration of concentration, light filtering and thermal management, and improves the comprehensive utilization efficiency and engineering applicability of solar full spectrum.

Description

Technical Field

[0001] This invention relates to the field of high-efficiency solar energy conversion and comprehensive utilization, specifically to an integrated liquid-filled spectral filter concentrator based on total internal reflection. It aims to achieve three major functions simultaneously through integrated optical structure design: high-efficiency light concentration, spectral selectivity control, and liquid heat absorption utilization. This improves the full-spectrum utilization efficiency of solar energy, reduces system optical loss, simplifies the structure, and enhances engineering applicability. Background Technology

[0002] In the field of renewable energy utilization technology, solar energy is considered one of the important ways to solve energy shortages and environmental problems due to its huge resource reserves, wide distribution, strong sustainability, and lack of pollutants during use. However, practical applications of solar energy generally suffer from problems such as low energy density, insufficient spectral utilization efficiency, and complex system structure, which limit its high-efficiency and large-scale application. Therefore, there is a need for an integrated optical device that can simultaneously achieve efficient light concentration and spectral selective control. An ideal solution is an integrated liquid-filled spectral filter concentrator, which aims to achieve efficient focusing of sunlight through a single compact structure, separate and guide the wavelengths suitable for photovoltaic conversion to the cells, and absorb and convert non-responsive wavelengths into heat energy for utilization, thereby improving the overall utilization efficiency of the entire solar spectrum and reducing the optical loss and structural complexity of the system.

[0003] To achieve the above functions, the existing technologies mainly employ the following types of technical means:

[0004] Firstly, in the field of liquid filtering and liquid focusing technologies, existing research has explored the separation of solar radiation at different wavelengths by introducing liquid media with selective absorption properties into the sunlight propagation path. This allows wavelengths suitable for photovoltaic conversion to pass through, while absorbing wavelengths unsuitable for photovoltaic conversion and converting them into heat energy. This technology has been researched and applied in photovoltaic-photothermal composite systems. Furthermore, some technologies propose using liquid-filled lenses or non-imaging optical structures to focus sunlight, controlling the light propagation path through the refractive index difference between the liquid and the outer casing material, thereby increasing light intensity. Other technical solutions attempt to fill the encapsulation cavity with liquids possessing wavelength-selective absorption properties, aiming to combine filtering and focusing functions.

[0005] Secondly, there are spectral modulation and light guiding technologies based on total internal reflection. Spectral filtering or light guiding technologies based on the principle of total internal reflection have been applied in the field of precision optics. For example, by setting a reflective interface at a specific angle inside the optical element, light can be selectively transmitted or reflected under the condition of total internal reflection, thereby achieving the separation or guidance of different wavelength components. Such technologies have the advantages of low optical loss and high optical path stability.

[0006] However, the aforementioned existing technologies have obvious defects and shortcomings in achieving the goal of an integrated liquid-filled spectral filter concentrator:

[0007] First, existing liquid filtering and focusing solutions suffer from limited optical efficiency and low functional integration. These devices primarily rely on refraction or multi-interface transmission for focusing. When light propagates through multiple media interfaces, reflection loss, absorption loss, and dispersion inevitably occur, leading to a decrease in overall optical efficiency. Simultaneously, the liquid in these solutions mainly serves absorption or cooling functions, and the optical path design remains primarily based on refraction or reflection, failing to establish a low-loss optical focusing path dominated by total internal reflection. This results in low synergistic efficiency between focusing and spectral filtering functions, leaving significant room for improvement in functional integration.

[0008] Secondly, existing total internal reflection optics technology has not been effectively integrated with solar energy spectral modulation and thermal management. Although optical elements based on total internal reflection have the advantage of low loss, they are mostly used in fields such as spectral analysis, imaging, or communication. They are usually not designed for high-throughput solar energy concentration scenarios, nor are they combined with liquid media with spectrally selective absorption functions. Therefore, it is difficult to achieve multiple functions such as efficient light concentration, spectrally selective modulation, and liquid heat absorption utilization in a single device.

[0009] Third, existing technical solutions suffer from insufficient structural complexity and engineering applicability. In the field of spectral separation and concentration, there are also technical solutions based on prisms, gratings, or Fresnel structures. These typically rely on high-precision optical processing, resulting in large device sizes, complex structures, and high manufacturing costs. Furthermore, existing solar concentrators utilizing total internal reflection are mostly used as auxiliary units, failing to incorporate liquid-filled media to form an integrated spectral filtering and concentrating structure dominated by total internal reflection. This leads to complex optical paths and lengthy structures, increasing manufacturing, installation, and maintenance costs, and hindering the engineering construction and promotion of efficient and compact solar energy utilization systems.

[0010] Therefore, existing technologies have not yet developed an integrated optical structure within the same device that is dominated by a total internal reflection optical path and combined with a liquid-filled medium. This makes it difficult to achieve a multifunctional, compact, and engineering-suitable integrated solar optical device while reducing optical energy loss. Overcoming these shortcomings has become a pressing technical challenge in this field. Summary of the Invention

[0011] To address the shortcomings of existing technologies, this invention discloses an integrated liquid-filled spectral filter and concentrator based on total internal reflection, the technical solution of which is as follows:

[0012] An integrated liquid-filled spectral filter and concentrator based on total internal reflection, comprising:

[0013] A sealed housing, wherein a sealed filling cavity is defined within the housing;

[0014] An optical focusing structure disposed within the filling cavity, the optical focusing structure including at least one total reflection wall as the dominant focusing interface, the total reflection wall being formed by the inner wall of the housing or the surface of a solid optical element disposed within the filling cavity;

[0015] The filling cavity is filled with a liquid medium with spectrally selective absorption characteristics, and the liquid medium is in direct contact with the total reflection wall to form a solid-liquid optical interface.

[0016] The concentrator is provided with an incident surface that allows sunlight to enter, and an exit surface for exporting light after total internal reflection and spectral selection.

[0017] The total internal reflection wall is arranged inwardly relative to the direction of incident light. Its spatial position and tilt angle are configured such that when sunlight enters from the incident surface and propagates to the interface, the incident angle at the solid-liquid interface satisfies the critical condition for total internal reflection, thereby changing the direction of the light in a total internal reflection manner and guiding it to the exit surface. The liquid medium is used to absorb the light energy of the photovoltaic non-response band in the solar spectrum and convert it into heat energy, while allowing the light of the photovoltaic response band to pass through.

[0018] The present invention also discloses a control method based on the above-mentioned concentrator, characterized in that the method includes the following steps:

[0019] Light focusing and guiding steps: Sunlight is incident perpendicularly or nearly perpendicularly from the incident surface of the concentrator; when the light propagates in the filling cavity to the total reflection wall, total reflection occurs at the solid-liquid interface formed by the liquid medium and the solid wall; the light, after being deflected by total reflection, continues to propagate and finally exits from the exit surface, concentrating on the surface of the photovoltaic cell.

[0020] Spectral modulation and thermal energy management steps: During the propagation of light, the liquid medium in the filling cavity selectively absorbs the non-responsive bands of the solar spectrum of photovoltaic cells and converts the absorbed light energy into heat energy; the generated heat energy is exported and utilized through the circulation of the liquid medium itself or an external circulation system, while cooling the photovoltaic devices in the concentrating area.

[0021] Beneficial effects

[0022] 1. Significantly reduces optical loss and improves light focusing and guiding efficiency.

[0023] By employing a focusing interface design dominated by a total internal reflection wall and precisely configuring its tilt angle and spatial position, the light beam satisfies the total internal reflection condition at the solid-liquid interface. This method fundamentally avoids the inherent reflection, absorption, and dispersion losses in traditional refractive or multi-interface transmission schemes. The light beam changes direction almost without loss inside the device and is efficiently guided to the exit surface, thereby achieving higher optical efficiency and a more stable optical path.

[0024] 2. Achieve integrated light concentration, spectral filtering, and thermal management to enhance system compactness and functionality.

[0025] By filling the focusing cavity with a liquid medium possessing spectrally selective absorption characteristics (such as thermally conductive oil-based nanofluids) and having it work in conjunction with a total internal reflection optical structure, three core functions are simultaneously achieved within a single device: efficient total internal reflection focusing, selective absorption and filtering of ineffective photovoltaic wavelengths, and conversion of absorbed light energy into usable heat energy. This integrated design effectively solves the problems of system complexity and low integration caused by functional separation in the prior art, realizing the synergistic output of optoelectronics and photothermal energy.

[0026] 3. Its compact structure and strong engineering applicability reduce manufacturing and maintenance costs.

[0027] The concentrator unit of this invention adopts a spatially expanded structure with progressively decreasing dimensions from top to bottom. Multiple units can be flexibly combined into linear or point-type concentrators. When multiple concentrator units are cascaded, their 'predetermined spatial relationship' is determined through optical path simulation of the emitted light from each unit. The goal is to make the emitted light spots of adjacent units partially overlap or closely adjacent on the receiving surface, seamlessly splicing them into a continuous high-density energy flux distribution. For a linear array, the unit spacing d is approximately equal to the width of the emitted light spot of a single unit; for a point array, the distribution radius R of the units around the receiving center is determined according to the convergence angle β of the emitted light from a single unit, ensuring that all light rays converge in the central region. This modular and array-based design allows the system to achieve a high overall concentration factor through static arrangement without relying on complex mechanical tracking structures. Its compact structure and easy expansion overcome the shortcomings of existing prism and grating solutions, which are complex in structure, bulky in size, and expensive in cost, making it more suitable for large-scale engineering applications.

[0028] 4. Effectively suppresses stray light, improving optical path purity and energy concentration.

[0029] By designing the total internal reflection wall to be inclined inward and avoiding direct illumination by incident light, while placing part of the exit interface in the shielded area of ​​the adjacent structure, this scheme effectively reduces the generation of undesigned optical paths and ineffective reflections from a structural perspective. This design ensures the stability of the converging spot position and the high concentration of energy flux density, thereby improving the final energy output quality of the system.

[0030] 5. Achieve efficient utilization of the "full spectrum" of solar energy, resulting in high overall energy efficiency.

[0031] The liquid medium, while performing spectrally selective filtering, also removes the absorbed heat energy through a circulation system. This heat can be used for independent heating or to reduce the operating temperature of photovoltaic cells, thereby improving their photoelectric conversion efficiency and lifespan. This process effectively utilizes both photon and thermal energy from solar radiation, fundamentally solving the problems of insufficient spectral utilization and thermally induced efficiency decline in conventional photovoltaic systems, and significantly improving the overall benefits of comprehensive solar energy utilization. Attached Figure Description

[0032] Figure 1 The present invention provides a schematic diagram of the structure and optical path of an integrated liquid-filled spectral filter and concentrator based on total internal reflection;

[0033] Figure 2 This is a side view of the structure of a single total internal reflection filter and focusing unit of the present invention;

[0034] Figure 3 This is a schematic diagram of the array structure of the concentrator units of the present invention arranged laterally;

[0035] Figure 4 This is a schematic diagram illustrating the optical path working principle of the concentrator of the present invention;

[0036] Figure 5 This is a three-dimensional structural diagram of the linear concentrator of the present invention;

[0037] Figure 6 This is a schematic diagram of the main structure of the linear concentrator of the present invention;

[0038] Figure 7 This is a top view of the linear concentrator of the present invention. Figure 8 This is a schematic diagram of the left-side structure of the linear concentrator of the present invention;

[0039] Figure 9 This is a three-dimensional structural diagram of the point concentrator of the present invention; Figure 10 This is a schematic diagram of the main structure of the point concentrator of the present invention.

[0040] Figure 11 This is a top view of the point concentrator structure of the present invention; Figure 12 This is a schematic diagram of the left-side structure of the point concentrator of the present invention.

[0041] Wherein: 01-incident surface; 02-total reflection wall; 03-exit surface. Detailed Implementation

[0042] Example 1

[0043] This embodiment provides an integrated liquid-filled spectral filter and concentrator based on total internal reflection. (See attached image) Figure 1 The core of this concentrator lies in its outer shell structure containing a sealed, filled cavity. This cavity is not empty; instead, it is filled with a specially selected liquid medium possessing spectrally selective absorption characteristics. Conventional concentrators typically contain air or a single transparent solid, which can only alter the optical path and cannot actively filter or utilize the spectrum. The filling liquid medium directly contacts the optical interface inside the concentrator, forming the physical basis for subsequent optical path manipulation.

[0044] The optical function of the concentrator is mainly achieved through its internal optical focusing structure. This structure presents a spatially unfolded form that decreases in size from top to bottom, consisting of multiple smoothly connected, inclined sidewall units surrounding a central axis, such as... Figure 2 As shown. The inner surface of each sidewall unit, i.e., the surface facing the interior of the cavity, is designed as a total reflection wall. The total reflection wall, which serves as the dominant focusing interface, is typically formed directly from the inner wall surface of the sealed housing (e.g., Figure 2 (Inner surface of the middle sidewall unit). Alternatively, the filling cavity may also contain independent solid optical elements (e.g., prisms or light guides made of highly transparent materials), whose surfaces are polished or coated to form the total internal reflection wall, where light undergoes total internal reflection at the interface between the solid element and the liquid medium. To simplify the structure and reduce costs, it is preferable to use the inner wall surface of the outer shell directly as the total internal reflection wall. Surface 01 serves as the light entry surface, surface 02 is the total internal reflection surface, and surface 03 is the exit surface, which is designed to be perpendicular to the light after total internal reflection, allowing the light to exit perpendicularly and reducing losses. Multiple chambers can be cascaded together through system design, such as... Figure 3 As shown, the lowest point of the inner concentrator is designed on the line of the light emitted from the innermost point of the outer concentrator, ensuring better focusing effect. These cascaded walls are not vertical or outwardly oriented, but rather all arranged inwardly relative to the direction of light incidence. This ensures that sunlight entering vertically from the top incident surface does not directly strike these sidewalls in its initial propagation path. If these walls were vertical or outwardly oriented, the incident light would inevitably undergo ordinary diffuse reflection or transmission, generating a large amount of uncontrollable stray light, severely reducing the system's optical efficiency and the purity of the converged light spot, resulting in poor light propagation after cascading. Figure 4 As shown, the inward tilt design avoids direct excitation from undesigned optical paths from the outset, which is a prerequisite for achieving a high-efficiency, clean optical path.

[0045] The core function of the total internal reflection wall is to form a solid-liquid optical interface. When light propagates to this interface, its angle of incidence can be pre-designed through geometric structure and material parameters. Assuming the refractive index of the selectively absorbing liquid is n1, then the critical angle for total internal reflection is... The angle of incidence onto the interface should be ensured during the design process. satisfy ≥ .

[0046] This invention aims to ensure that the angle of incidence of light reaching this interface is greater than or equal to a critical angle. At this point, the light no longer follows the law of refraction to penetrate the liquid or undergo partial reflection; instead, it undergoes total internal reflection at the solid-liquid interface, changing direction with almost no energy loss, and is completely confined and guided to the target area below the concentrator. Traditional concentrators rely on lens refraction or specular reflection; the former suffers from dispersion and transmission loss, while the latter suffers from absorption and diffuse reflection loss. Total internal reflection, as a theoretically near-lossless optical phenomenon, is used as the dominant concentrating mechanism, fundamentally and significantly reducing energy loss during light propagation at multi-medium interfaces. The light guided by the total internal reflection wall ultimately needs to be efficiently extracted and utilized. For this purpose, an exit surface is provided at the bottom of the concentrator. Depending on the final propagation direction of the light, the exit surface can be specifically designed to exit vertically from the bottom. This allows it to exit with low loss in a direction close to the interface normal, directly illuminating the surface of the photovoltaic cells below, avoiding unnecessary secondary reflections internally, and ensuring that unnecessary interface occurrences and reflection losses are minimized throughout the entire path from light incident to final convergence.

[0047] During operation, the liquid medium plays an irreplaceable synergistic role. Sunlight contains a broad spectrum of energy, but ordinary silicon-based photovoltaic cells can only effectively convert photons in specific wavelengths. When full-spectrum sunlight propagates within the cavity, the liquid medium selectively absorbs the non-responsive photovoltaic wavelengths and converts light energy into heat energy.

[0048] By adding nanoparticles with strong absorption characteristics for non-responsive wavelengths (such as localized surface plasmon resonance peaks in this wavelength range) to the base liquid and controlling their concentration, the spectral absorption coefficient of the liquid medium can be kept relatively small in the photovoltaic response wavelength range and exhibit a larger value in the non-responsive wavelength range. Combined with the light propagation path length or its cumulative equivalent length in the device liquid, the spectral modulation objective of 'maximizing the transmission of photovoltaic response wavelengths and maximizing the absorption of non-responsive wavelengths by the liquid and their conversion into heat energy' can be achieved.

[0049] Simultaneously, it maintains high transmittance in the effective response band of photovoltaic cells, allowing this portion of light to continue propagating almost unaffected, ultimately reaching the cell after total internal reflection. This process achieves spectral filtering. The heat energy absorbed by the liquid can significantly increase the liquid's own temperature. By designing a circulating pipeline system connected to it, this heat energy can be actively extracted for heating, hot water, or other heat utilization scenarios, realizing photothermal utilization. At the same time, the flowing liquid also directly carries away the waste heat generated by the concentrating area and photovoltaic cells, playing a role in active cooling and suppressing the efficiency degradation of the cells caused by temperature increases. Therefore, the liquid-filled design achieves three major functions in one go: spectral frequency division, waste heat recovery, and device cooling, highly integrating and solving the system complexity problem of separating concentrating, filtering, and thermal management functions.

[0050] To achieve selective absorption of non-responsive wavelengths (such as infrared light >1200nm) in photovoltaic cells (e.g., crystalline silicon cells, with a response wavelength of approximately 300-1200nm), the liquid medium can be formulated as follows: using dimethyl silicone oil as the base liquid, and dispersing silicon carbide (SiC) nanoparticles (average particle size approximately 50nm) with a volume fraction of approximately 0.005%. This nanofluid exhibits high transmittance in the visible to near-infrared wavelength range (300-1200nm), while displaying strong absorption characteristics in the mid-to-far-infrared wavelength range above 1200nm. The nanoparticles are dispersed by ultrasonic vibration, and an appropriate amount of dispersant (such as oleylamine) is added to maintain long-term stability. Those skilled in the art can select other nanoparticles with similar spectral characteristics, such as CuO or SiO2@Au core-shell structures, for absorbing specific wavelengths, based on the response spectrum of the target photovoltaic cell. Alternatively, the liquid medium can also be made of heat-conducting oil such as hydrogenated terphenyl as the base liquid, and dispersed with copper oxide (CuO) nanoparticles (volume fraction of about 0.01%), which can also achieve a similar spectrally selective absorption function.

[0051] To adapt to different application scenarios and higher requirements for concentration ratio, the concentrator unit of this invention has good scalability. (See attached diagram) Figure 3 As shown, multiple basic concentrator units can be cascaded in an array. This design eliminates the need for complex mechanical solar tracking systems, achieving a significant increase in concentrating effect simply through static structural arrangement, greatly enhancing the practicality and economy of the project.

[0052] Preferably, the array-cascaded design is as follows (taking a linear array as an example): Assume the target focusing power is 9 times, the incident surface of a single focusing unit is square with a side length a = 100 mm and a height H = 150 mm, and the tilt angle γ of the total reflection wall is designed to be 15° (to ensure total reflection conditions are met for perpendicularly incident light). Ray tracing simulation shows that the beam width w formed by a single unit at the receiving surface (50 mm from the exiting surface) is approximately 12 mm. To achieve seamless splicing to form a continuous linear high-energy flow, N = 9 of these units are arranged in a straight line, with the center-to-center distance d between adjacent units set to the beam width w, i.e., d = 12 mm. At this point, the total incident area is 9 * (100 mm * 100 mm) = 90000 mm². If the beam emitted by a single unit on the receiving surface is rectangular with a width w = 12 mm and a length equivalent to the side length a of the unit's incident surface (approximately 100 mm), then the area of ​​a single beam is approximately 1200 mm². After seamless stitching together multiple light spots, the total converged light spot area is approximately 9 * 1200 mm² = 10800 mm². Therefore, the geometric focusing ratio (total incident area / total converged light spot area) is approximately 90000 / 10800 ≈ 8.3 times. The "predetermined spatial relationship" refers to this arrangement based on the spacing d determined by the light spot width w. Through optimized design (e.g., further reducing the light spot width w or adjusting the unit spacing d), the geometric focusing ratio can be made closer to or reach the target of 9 times. For point arrays, a similar principle can be used to determine the radius R of the annular distribution based on the coverage of individual unit light spots in the central region.

[0053] In practice, the cascading method can be flexibly varied: as shown in the attached figure. Figure 5-8 As shown, arranging multiple units along a single direction can form a linear cascaded concentrator structure with a rectangular emitted light spot, making it highly suitable for matching with linearly arranged photovoltaic cells or tubular photothermal absorbers; as shown in the attached diagram. Figure 9-12 As shown, arranging multiple units around a central axis in a ring or radial pattern can form a point-type cascaded concentrating structure. Its emitted light spot converges at a central point, which can generate extremely high power density. This structure is suitable for small-area, high-performance photovoltaic cells or thermal power receivers that require extreme light concentration.

[0054] This invention achieves low-loss light focusing and guiding through an inwardly tilted total internal reflection solid-liquid interface, integrates spectral filtering and heat recovery through spectrally selective absorption of liquid, and balances system compactness and light focusing capability through a modular spatial unfolding structure and cascadeable array design.

[0055] Example 2

[0056] A control method based on the above-mentioned total internal reflection integrated liquid-filled spectral filter concentrator achieves efficient conversion and comprehensive utilization of solar energy through a set of synergistic optical and thermodynamic processes.

[0057] The design of the focusing device is as follows:

[0058] Establish a two-dimensional cross-sectional coordinate system: the y-axis points vertically downwards, and the x-axis is horizontal. Let the inward tilt angle of the total internal reflection wall relative to the vertical direction within the cross-section be β, and the incident light be approximately vertically downwards. Then the incident angle can be approximated as... To account for temperature variations, manufacturing errors, and installation / tracking errors, a safety margin can be introduced. (Approximately 3°-8°), making Right now: (in ).

[0059] If the angle of incidence is less than the critical angle, most of the light rays will enter the liquid according to the law of refraction and undergo uncontrollable scattering or absorption, resulting in severe energy loss and optical path disorder. This is one of the fundamental reasons for the limited efficiency of traditional refractive concentrators. The total internal reflection forced by this invention allows light to change direction at the interface with almost no energy loss. This propagation mechanism fundamentally eliminates the transmission loss, reflection loss, and dispersion effects caused by multi-interface refraction, greatly improving the purity and efficiency of light guidance.

[0060] Guided by total internal reflection, the propagation direction of the light is uniformly adjusted, and it is ultimately concentrated and emitted from the exit surface, forming a high-energy-density light spot that precisely illuminates the surface of the photovoltaic cell. This focusing process is stable and efficient, providing excellent incident conditions for photoelectric conversion.

[0061] Parallel to the aforementioned pure optical path guidance is the intelligent spectral selection and energy form conversion performed by the liquid medium. Throughout the entire propagation of sunlight within the cavity, the spectrally selective absorbing liquid filling it continuously operates. For specific wavelengths that photovoltaic cells can efficiently respond to, the liquid maintains high transparency, allowing them to pass through with almost no attenuation, participating in the subsequent concentration and power generation process; while for wavelengths that the cells cannot utilize or utilize at low rates, the liquid exhibits strong absorption. This selective absorption is not the end point, but a precise conversion of energy form—the absorbed photon energy is not dissipated meaninglessly, but is almost entirely converted into the thermal energy of liquid molecules, thus significantly increasing the liquid's own temperature. This process resolves the inherent contradiction in conventional concentrated photovoltaic systems where ineffective spectral components are converted into harmful waste heat, leading to cell heating and efficiency reduction. It transfers the originally harmful waste heat from the cell area and traps it in the circulating liquid, converting it into usable clean thermal energy.

[0062] Thus, this method naturally leads to a closed-loop thermal energy management system. The liquid medium, having absorbed a large amount of heat, is actively pumped out through an integrated external circulation pipeline system. The extracted high-temperature liquid can be directly used for heating, industrial preheating, or driving thermodynamic cycles to achieve solar thermal utilization; simultaneously, the returned low-temperature liquid continuously cools the concentrator body and the photovoltaic cells below, maintaining the cells within their efficient operating temperature range. In this way, the liquid medium is not only a static optical filter but also a dynamic, bidirectional energy transporter and temperature regulator, simultaneously completing three tasks—spectral frequency division, heat harvesting, and active thermal management—that traditionally require separate systems within the same physical space and process. This deep functional integration is the creative embodiment of this invention overcoming the shortcomings of existing technologies, such as "complex system structure and low integration."

[0063] When total internal reflection is satisfied, the wall surface is equivalent to specular reflection. For vertically downward incident light, the angle of deflection of the reflected light relative to the vertical direction is: To ensure that the rays emitted from the outermost boundary of a given element converge at a designated location, let H be the vertical distance from the equivalent reflection point to the receiving plane, and x be the horizontal distance from the reflection point to the target convergence point. Then the geometric relationship is: Substitute The formula for calculating the wall inclination angle can be obtained directly: Let the exit point of the boundary rays emitted from the i-th concentrator within the cross-section be... The launch direction deflects inward relative to the vertical at an angle of _____. (Depend on (Obtained). A unified horizontal reference line for the array is taken as... ; and horizontal line The x-coordinate of the intersection point is: The intersection point Defined as "the lowest point of the next inner concentrator (i-1)". The boundary rays of the outer unit just brush past the lowest point of the inner unit and enter its effective focusing area, realizing "multi-unit boundary convergence inwards step by step", and because y i Differences are allowed; the height of each unit can be different, satisfying the degree of freedom in layout where the heights do not have to be the same.

[0064] Furthermore, when this control method is applied to an array-type focusing system composed of multiple basic units, its advantages are further amplified. Each focusing unit independently and in parallel performs the aforementioned total internal reflection focusing and spectral modulation processes.

[0065] The luminous flux and energy density on the overall receiving surface are the linear sum of the contributions from each individual unit, thus achieving a concentration multiple several times or even tens of times greater than that of a single unit. This design does not rely on a mechanical solar tracking system. Once installed and fixed, the system can stably output high-concentration energy during periods when the sun is approximately perpendicular to the ground, greatly enhancing the reliability, economy, and maintainability of the technology in engineering applications, and solving the problem of widespread adoption of existing high-concentration solar systems that rely too heavily on tracking mechanisms.

[0066] The integrated liquid-filled spectral filter and concentrator based on total internal reflection and its control method provided by this invention successfully constructs a low-loss concentrating optical path dominated by total internal reflection by adopting an optical interface design with an inwardly tilted total internal reflection wall as the core. This fundamentally avoids the inherent energy loss in traditional refraction or multi-interface reflection schemes and significantly improves the optical efficiency and optical path stability of the system.

[0067] By filling the sealed cavity with a liquid medium with spectrally selective absorption characteristics, this solution achieves efficient light concentration while simultaneously completing intelligent frequency division of the solar spectrum: it guides the effective photovoltaic bands to the battery without loss, while absorbing the non-responsive bands and converting them into directly usable heat energy. Thus, it highly integrates light concentration, light filtering, and photothermal recovery functions in a single compact device, effectively solving the problems of functional module separation and lengthy and complex systems in existing technologies.

[0068] Furthermore, through a modular spatial unfolding structure and a flexible cascaded array layout, the light-gathering capability under static conditions is multiplied and expanded, overcoming the dependence on high-precision tracking mechanisms and enhancing the practicality and economy of the project.

[0069] Furthermore, the continuous circulation of the liquid medium not only achieves effective heat collection but also provides active cooling for the photovoltaic devices, enhancing the long-term reliability of the system. Therefore, through the aforementioned synergistic technical means, this invention not only comprehensively addresses the technical challenges of low energy density, insufficient spectral efficiency, and system complexity in solar energy utilization but also provides an innovative, highly efficient, highly integrated, compact, and easily scalable full-spectrum solar energy utilization solution, demonstrating significant technological advancement and practical value.

Claims

1. An integrated liquid-filled spectral filter and concentrator based on total internal reflection, characterized by: A sealed housing, wherein a sealed filling cavity is defined within the housing; An optical focusing structure disposed within the filling cavity, the optical focusing structure including a total reflection wall serving as the dominant focusing interface, the total reflection wall being formed by the inner wall of the outer shell; The filling cavity is filled with a liquid medium with spectrally selective absorption characteristics, and the liquid medium is in direct contact with the total reflection wall to form a solid-liquid optical interface. The concentrator is provided with an incident surface that allows sunlight to enter, and an exit surface for exporting light after total internal reflection and spectral selection. The total internal reflection wall is arranged inwardly relative to the direction of incident light. Its spatial position and tilt angle are configured such that when sunlight enters from the incident surface and propagates to the interface, the incident angle at the solid-liquid interface satisfies the critical condition for total internal reflection, thereby changing the direction of the light in a total internal reflection manner and guiding it to the exit surface. The liquid medium is used to absorb the light energy of the photovoltaic non-response band in the solar spectrum and convert it into heat energy, while allowing the light of the photovoltaic response band to pass through.

2. The integrated liquid-filled spectral filter and concentrator based on total internal reflection according to claim 1, characterized in that, The exit surface is used to direct the light, guided by total internal reflection, vertically downwards to connect with the photovoltaic cell.

3. The integrated liquid-filled spectral filter and concentrator based on total internal reflection according to claim 1, characterized in that, The optical focusing structure is a spatially unfolded structure that gradually decreases from top to bottom. It consists of multiple inclined sidewall units that are continuously connected along the height direction. The inner surface of each sidewall unit forms the total reflection wall and is arranged around the central axis of the focusing device.

4. The integrated liquid-filled spectral filter and concentrator based on total internal reflection according to claim 1, characterized in that, The inward tilting arrangement of the total reflection wall is configured to prevent vertically incident sunlight from directly hitting the wall surface, thereby suppressing the generation of stray light.

5. The integrated liquid-filled spectral filter and concentrator based on total internal reflection according to claim 1, characterized in that, An array-type focusing structure unit formed by cascading multiple concentrators according to a predetermined spatial relationship; The positional relationship of adjacent concentrator units is set according to the propagation direction of their respective emitted light rays, so that the emitted light rays of multiple units are superimposed in space and converged into a common receiving area.

6. The integrated liquid-filled spectral filter and concentrator based on total internal reflection according to claim 5, characterized in that, The array-type focusing structure is a linear cascaded focusing structure, in which multiple focusing units are arranged along a single direction, and their emitted light rays converge to form a linear high energy flux density region; or, the array-type focusing structure is a point-type cascaded focusing structure, in which multiple focusing units are arranged in a ring or radial arrangement around a central axis, and their emitted light rays converge toward the central region to form a point-type high energy flux density region.

7. The integrated liquid-filled spectral filter and concentrator based on total internal reflection according to claim 1, characterized in that, The liquid medium with spectrally selective absorption characteristics is a spectrally selective absorption nanofluid.

8. A control method for an integrated liquid-filled spectral filter concentrator based on total internal reflection according to any one of claims 1 to 7, characterized in that, The method includes the following steps: Sunlight enters the concentrator perpendicularly or nearly perpendicularly from its incident surface. As the light propagates within the filling cavity to the total internal reflection wall, total internal reflection occurs at the solid-liquid interface formed by the liquid medium and the solid wall. The light, deflected by total internal reflection, continues to propagate and ultimately exits perpendicularly from the exit surface, concentrating on the photovoltaic cell surface. During this process, the liquid medium within the filling cavity selectively absorbs the non-responsive wavelengths of the solar spectrum from the photovoltaic cells, converting the absorbed light energy into heat energy. The generated heat energy is discharged and utilized through the liquid medium's own circulation or an external circulation system, simultaneously cooling the photovoltaic devices in the concentrating region.

9. The control method according to claim 8, characterized in that, In the light converging and guiding step, the tilt angle design of the total reflection wall ensures that the incident angle of the incident light at the interface is always greater than or equal to the critical angle of total reflection, so that the dominant propagation process of the light inside the concentrator is total reflection, thereby minimizing optical losses caused by refraction and multi-interface reflection.

10. The control method according to claim 8, characterized in that, When the concentrator is an array-type concentrating structure, the method further includes: multiple concentrator units working simultaneously, each unit independently guiding and converging the incident light according to its preset spatial position and total internal reflection optical path; the converged light rays of all units are spatially superimposed in the target receiving area, thereby achieving a higher overall concentrating power than a single unit, and this process does not rely on a complex mechanical solar tracking system.

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