A back heat collecting plate of photovoltaic and photo-thermal integrated panel

Abstract

This utility model relates to the field of solar energy utilization technology and discloses a photovoltaic-thermal integrated panel back heat collector, including a heat collector body. A flow channel is formed on one side of the heat collector body. The flow channel is biomimetic blood vessel-shaped and includes a main inlet channel, a multi-level branch flow channel, and a main outlet channel connected in sequence. The multi-level branch flow channel extends out from the main inlet channel in stages. The multi-level branch flow channel structure enables the heat-conducting fluid to be more evenly distributed throughout the heat collector body, reducing local overheating or undercooling. According to experimental comparison, under the same conditions, the heat exchange efficiency is increased by 12%-20% compared with the serpentine flow channel, thus making the heat exchange efficiency higher. At the same time, it avoids the high-resistance structure such as sharp bends and narrow channels of the traditional serpentine flow channel. Under the same flow rate, the flow resistance is reduced by 15%-25% compared with the honeycomb flow channel, reducing power consumption and thus reducing flow resistance while maintaining reasonable flow resistance.

Description

Technical Field

[0001] This utility model relates to the field of solar energy utilization technology, and in particular to a back heat collector plate of a photovoltaic-thermal integrated panel. Background Technology

[0002] In the field of photovoltaic-thermal integrated panels, the flow channel design of the back heat collector has a significant impact on performance such as heat transfer efficiency and fluid flow resistance. Existing flow channels are mostly honeycomb or serpentine: although the serpentine flow channel has a regular structure, its fluid flow path is relatively simple, making it difficult to adapt to complex heat flow distribution requirements and prone to uneven local heat exchange; the honeycomb flow channel enhances heat exchange to a certain extent, but the flow resistance is large and the flow channel is prone to breakage.

[0003] With the increasing demands for improved heat collection efficiency and energy utilization in photovoltaic and solar thermal technologies, there is an urgent need for a new type of flow channel structure that can balance efficient heat exchange with reasonable flow resistance. Utility Model Content

[0004] To address the aforementioned technical issues, this utility model provides a back heat collector plate for a photovoltaic-thermal integrated panel, which can balance efficient heat exchange with reasonable flow resistance.

[0005] A photovoltaic-thermal integrated panel back heat collector includes a heat collector body, with a flow channel formed on one side of the heat collector body. The flow channel is biomimetic blood vessel-shaped and includes a main inlet channel, a multi-level branch flow channel, and a main outlet channel connected in sequence. The multi-level branch flow channel extends out from the main inlet channel in stages.

[0006] Optionally, the flow channel is blown up.

[0007] Optionally, the main inlet channel and the main outlet channel are symmetrically distributed, and the cross-sectional shape of the main inlet channel and the main outlet channel is circular with a diameter of 8 mm to 10 mm.

[0008] Optionally, the connection points between adjacent channels in the main inlet channel, multi-level branch channels, and main outlet channel can be smoothly transitioned.

[0009] Optionally, the multi-level branch channels can be merged at their ends or independently connected to the main outflow channel.

[0010] Optionally, the density of branch channels in the concentrated heat generation area of ​​the photovoltaic cells on the heat collector plate is greater than the density of branch channels in the area with uniform heat distribution.

[0011] Optionally, the heat collection plate body includes two sub-plates spliced ​​together as one piece. The connection between the two sub-plates has a connecting surface formed by bending, and the two sub-plates are connected by fixing the two connecting surfaces.

[0012] Optionally, the water inlet ends of the two sub-plates form a water inlet located at the beginning of the main inlet channel, and the water outlet ends of the two sub-plates form a water outlet located at the end of the main outlet channel. The water inlet and the water outlet are arranged opposite to each other, and there is a junction box on each side of the heat collector plate body.

[0013] Optionally, the solar collector panel body can be integrated with the photovoltaic layer using structural adhesive.

[0014] The technical solution provided by this utility model has the following advantages compared with the prior art: This utility model provides a photovoltaic-thermal integrated panel back heat collector plate. A flow channel is formed on one side of the heat collector plate body, designed in a biomimetic blood vessel shape. The flow channel includes a main inlet channel, multi-level branch channels, and a main outlet channel connected in sequence. The multi-level branch channels extend from the main inlet channel in stages. This multi-level branch channel structure allows the heat-conducting fluid to be more evenly distributed throughout the entire heat collector plate body, reducing local overheating or undercooling. Experimental comparisons show that, under the same conditions, the heat exchange efficiency is 12%-20% higher than that of a serpentine flow channel, resulting in higher heat exchange efficiency. Simultaneously, it avoids the high-resistance structures such as sharp bends and narrow channels of traditional serpentine flow channels. At the same flow rate, the flow resistance is reduced by 15%-25% compared to a honeycomb flow channel, reducing power consumption and thus lowering flow resistance while maintaining reasonable flow resistance. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of the back heat collector of a photovoltaic-thermal integrated panel provided in an embodiment of the present utility model.

[0016] Explanation of reference numerals in the attached figures: 1. Inlet; 2. Flow channel; 3. Junction box; 4. Outlet. Detailed Implementation

[0017] The following describes a specific embodiment of the present invention in detail with reference to the accompanying drawings. However, it should be understood that the scope of protection of the present invention is not limited to the specific embodiment.

[0018] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the technical solution of this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0019] The present invention will be described below through several specific embodiments. To keep the following description of the embodiments of the present invention clear and concise, detailed descriptions of known functions and components may be omitted. When any component of an embodiment of the present invention appears in more than one drawing, the component may be represented by the same reference numerals in each drawing.

[0020] refer to Figure 1 , Figure 1 A schematic diagram of the structure of the back heat collector of a photovoltaic-thermal integrated panel is provided for an embodiment of this utility model, as shown below. Figure 1 As shown, this embodiment of the utility model provides a photovoltaic-thermal integrated panel back heat collector, including a heat collector body. One side of the heat collector body forms a flow channel 2, which is biomimetic in shape. The flow channel 2 includes a main inlet channel, multi-level branch channels, and a main outlet channel connected in sequence. The multi-level branch channels extend from the main inlet channel in stages. The heat collector body is made of aluminum alloy and is manufactured through etching, 3D printing, or injection molding. One side of the heat collector body is precision-machined to form a closed biomimetic blood vessel-like flow channel system. Specifically, the flow channel system can be divided into three or more levels of branches: the first-level branch channels extend from both sides or one side of the main inlet channel; the second-level branch channels further extend from the first-level branch channels, and so on, forming a dense flow channel network that is progressively finer and evenly distributed. Finally, these fine branch channels converge step by step and connect to the main outlet channel. This biomimetic, blood vessel-like, multi-level branched structure significantly increases the heat exchange area, ensuring uniform flow of the cooling medium across the panel surface without dead zones. This results in a substantial reduction in the photovoltaic panel's operating temperature while efficiently collecting and outputting heat energy. Its advantages lie in a more balanced flow resistance distribution and higher heat exchange efficiency, effectively improving the overall energy utilization rate of the photovoltaic-thermal system.

[0021] The human vascular system possesses highly efficient material (heat analogous to material transfer) transport and heat exchange functions. Its hierarchical branching and converging structure enables uniform and efficient energy transfer, providing biomimetic inspiration for novel flow channel designs. This utility model provides a photovoltaic-thermal integrated panel back heat collector that forms a flow channel on one side of the heat collector body. The flow channel is designed in a biomimetic blood vessel shape, comprising a main inlet channel, multi-level branched flow channels, and a main outlet channel connected in sequence. The multi-level branched flow channels extend from the main inlet channel in stages. This multi-level branched flow channel structure allows the heat-conducting fluid to be more evenly distributed throughout the heat collector body, reducing local overheating or undercooling. Experimental comparisons show that, under the same conditions, the heat exchange efficiency is 12%-20% higher than that of a serpentine flow channel, resulting in higher heat exchange efficiency. Simultaneously, it avoids the high-resistance structures such as sharp bends and narrow channels of traditional serpentine flow channels. At the same flow rate, the flow resistance is 15%-25% lower than that of a honeycomb flow channel, reducing power consumption and thus lowering flow resistance while maintaining reasonable flow resistance.

[0022] Optionally, the flow channel 2 is formed by blow molding. This biomimetic blood vessel-like flow channel system is manufactured in one step using an advanced blow molding process. The manufacturing process is as follows: First, two flat metal sheets (usually aluminum or aluminum alloy) are stacked one on top of the other and rolled together under high temperature and pressure using a rolling mill, leaving only partially bonded channels in the pre-designed flow channel pattern area. Then, the bonded plate is moved to a sealed mold, and high-pressure inert gas is applied to the internal channels for "blow molding," forcing the unbonded metal layers to undergo plastic deformation within the space defined by the mold, thereby precisely forming the three-dimensional sealed flow channels required by the design. Finally, after cooling and shaping, the heat collector plate body with complex, continuous, and seamless internal flow channels is obtained.

[0023] The core advantages of the blow molding process are: the entire flow channel system is formed within a single, solid metal plate, without any welds or joints. This completely eliminates the leakage risks associated with welding, significantly improving the sealing reliability and service life of the heat collector plate under long-term high-temperature and high-pressure operating conditions. The blow-formed flow channel wall and the heat collector plate body form a natural, integrated metal structure, achieving zero-contact thermal resistance between the flow channel and the heat absorber plate. This ensures that heat can be efficiently and losslessly transferred from the plate surface to the cooling medium within the flow channel, with thermal conductivity far exceeding that of traditional welding or pipe binding methods. This process is suitable for large-scale continuous production, with high single-blow molding efficiency, effectively reducing unit production costs. Simultaneously, it can precisely replicate complex and intricate biomimetic flow channel patterns (such as multi-level branch networks), achieving an optimal balance between performance and manufacturing cost. The internal hollow flow channel structure, after blow molding, forms a reinforcing effect similar to "ribs," significantly enhancing the overall rigidity and deformation resistance of the heat collector plate with only a slight increase in material usage.

[0024] Optionally, the main inlet and outlet channels are symmetrically distributed, usually arranged parallel to each other on both sides of the long or short edge of the collector plate. This symmetrical layout is not simply visual symmetry, but a functional design based on fluid dynamics and thermodynamic optimization. The symmetrical inlet and outlet channels constitute the "main artery" and "main vein" of the entire flow channel system, providing a stable and symmetrical fluid dynamic foundation for the complex internal biomimetic branch network. It ensures that after the medium enters from the main inlet channel, it can be distributed almost uniformly to each level of branch channel, covering the entire collector plate body. At the same time, the heated medium can also be efficiently and smoothly collected into the main outlet channel, minimizing dead zones or eddies caused by uneven flow resistance, thereby achieving global high-efficiency heat exchange. The cross-sectional shape of the main inlet and outlet channels is circular. The circular cross-section is the optimal shape for withstanding internal fluid pressure, and has the smallest perimeter under the same cross-sectional area. This means that the required wall thickness is thinner, less material is used, and the weight is lighter when withstanding the same internal pressure. Meanwhile, the inner wall of the circular flow channel has no sharp corners, resulting in low fluid flow resistance (friction resistance), which is conducive to the smooth passage of the medium. The cross-sectional diameter is 8 mm to 10 mm. This size range not only ensures the balance between fluid flow rate and heat exchange efficiency, but also reduces system energy consumption and operating costs, while also being suitable for engineering installation and space compatibility.

[0025] Optionally, the connections between adjacent channels in the main inlet channel, multi-stage branch channels, and main outlet channel can be smoothly transitioned using arc-shaped or gradually changing cross-sections. All connections between adjacent channels abandon traditional right-angle or acute-angle connections, instead employing arc-shaped transitions or gradually changing cross-sections that conform to fluid dynamics. When the cooling medium flows through channel branches or confluences, if a right-angle connection is used, the sudden change in flow direction will generate severe eddies and flow separation, leading to a sharp increase in local resistance (referred to as "local resistance loss"). Arc-shaped transitions (such as using circular curves) or gradually changing cross-sections (such as a gradual change in the channel cross-sectional shape) can guide the fluid to smoothly change direction or velocity, greatly reducing the generation of eddies and flow resistance, thereby significantly reducing the total pressure drop of the entire channel system, reducing pump power consumption, and improving system operating efficiency.

[0026] Under fluid pressure (especially pulse pressure or thermal expansion and contraction stress), right-angle connections are weak points where stress concentrates, making them prone to metal fatigue, cracking, and leakage during long-term operation. A smooth, arc-shaped transition can evenly distribute stress over a wider area, avoiding stress concentration and significantly improving the structural integrity and durability of the heat collector plate under long-term pressure and high-temperature cycling conditions. At branch channels, a smooth transition ensures a more equitable distribution of fluid to each downstream branch. Right-angle connections tend to lead to uneven flow distribution, with most fluid flowing straight into the branch facing the main flow direction, while the flow to the lateral branches decreases. An arc-shaped flow guide design can improve this problem, allowing the cooling medium to be more evenly distributed in all branch channels, thus ensuring a more uniform temperature field on the heat collector plate surface, avoiding localized overheating, and improving overall heat exchange efficiency. Violent fluid impacts on right-angled walls generate audible noise. A smooth transition makes fluid flow more stable, effectively reducing operating noise. Simultaneously, it avoids cavitation phenomena that may be caused by sudden changes in flow rate and pressure (when the local pressure is lower than the fluid's saturated vapor pressure, bubbles form in the liquid, which then collapse in the high-pressure zone, impacting the wall and causing erosion), protecting the inner wall of the flow channel from damage. This smooth transition is not merely an engineering optimization; it deeply mimics the morphology of biological blood vessel branches in nature. The angles and connection curves of blood vessel branches optimized by biological evolution are precisely for minimizing the energy consumption of blood flow. Therefore, this design is a successful application and practice of biomimetic principles in engineering.

[0027] Optionally, the multi-level branch channels can be merged at their ends or independently connected to the main outflow channel. The specific mode adopted depends on the overall channel layout, hydraulic calculations, and performance priorities.

[0028] This method of terminal confluence and connection simulates the convergence pattern of a venous system. Starting from the smallest terminal branch channel, the heated medium does not directly enter the main outlet channel but first flows backward into the secondary branch channel of the next higher level. The medium from multiple secondary branch channels then flows into the coarser upper-level channel, and so on. Through this step-by-step convergence, the flow rate continuously increases, finally entering the main outlet channel smoothly through a few or one concentrated confluence point. This step-by-step confluence method makes the changes in fluid flow and pressure more gradual, avoiding pressure fluctuations and potential water hammer effects caused by a large number of small channels simultaneously impacting the main channel, resulting in more stable system operation. It also reduces the number of interfaces directly connected to the main outlet channel, lowering the probability of leakage or structural failure at these connection points. Furthermore, it requires fewer openings or interfaces when connecting to the main channel, reducing the complexity of blow molding or subsequent processing.

[0029] This independent connectivity approach simulates the concept of "parallel" or "capillary-collecting tubes" and is commonly used in designs that pursue ultimate uniformity. Each (or each group of) terminal branch channels maintains its independence and is directly connected to the main outflow channel. All terminal channels inject the medium they carry into the main channel almost simultaneously.

[0030] The core advantages are: due to the similar topology of the "starting point" and "ending point" of each flow path, the resistance encountered is very close, achieving excellent flow distribution uniformity. This ensures a highly consistent cooling effect across the entire plate surface, minimizing the generation of localized hot spots. In the "combined" type, the hotter fluid that merges first may mix with the cooler fluid that merges later, resulting in a slight decrease in the representativeness of the output fluid temperature. The "independent" connection ensures that the fluids in all branches hardly mix before entering the main channel, more accurately reflecting the overall heat transfer situation of the plate surface, resulting in a higher average temperature and superior heat quality of the output fluid.

[0031] Existing back-mounted heat collectors have flow channels that are difficult to adapt to the heat distribution characteristics of photovoltaic panels. Therefore, in this embodiment of the invention, the density of branch flow channels in the concentrated heat-generating area of ​​the photovoltaic cells is greater than that in the area with uniform heat distribution. Furthermore, the overall flow channel layout is optimized according to the heat distribution characteristics of the integrated photovoltaic and thermal panel, resulting in a relatively increased density of branch flow channels in the concentrated heat-generating area of ​​the photovoltaic cells.

[0032] This design offers better adaptability, allowing for precise adjustment of the density and direction of the branch flow channels to meet the heat flow requirements of different areas of the photovoltaic-thermal integrated panel. This helps stabilize the operating temperature of the photovoltaic cells and improves the synergy between photovoltaic power generation efficiency and photothermal conversion.

[0033] During processing, the heat collector plate body consists of two sub-plates spliced ​​together. The connection between the two sub-plates has a connecting surface formed by bending. The two sub-plates are connected by fixing the two connecting surfaces. The edges of the two 2245mm×600mm×1.4mm sub-plates are folded up and riveted together to form a single plate of 2245mm×1160mm×1.4mm.

[0034] The solar collector plate employs an advanced modular splicing structure. It is not made from a single sheet material, but rather composed of two independent sub-plates joined together along their length. The core of this design lies in its unique connection method: at the edges where each sub-plate needs to be connected, the sheet material is not simply flat and straight; instead, it is pre-processed with a specific shape, perpendicular or inclined to the main plane of the solar collector plate (or "flanged edge"), through stamping or bending processes. The connecting surfaces of the two sub-plates are aligned and fitted together, and fixed using a series of mechanical fasteners (such as bolts and rivets) or welding. This "face-to-face" fixing method provides significantly greater connection strength and stability compared to traditional direct butt joints or overlaps. It effectively resists internal fluid pressure, warping deformation caused by thermal stress, and external installation loads, ensuring the structural integrity of the entire solar collector plate under harsh operating environments. At the joint of the two connecting surfaces, a continuous sealing material (such as silicone gaskets or high-temperature sealant) can be pre-laid, and then uniform clamping force is applied using fasteners, thus forming a high-strength, high-reliability sealing surface. This sealing method is far more controllable and reliable than welding seals at the edges of thin plates, greatly reducing the risk of leakage at the splicing points and ensuring the long-term airtightness of the flow channel system; this is one of the core advantages of this design. This splicing method overcomes the size limitations of large single-panel production and transportation; it allows for standardized production of smaller sub-panels, reducing production difficulty and increasing yield; sub-panels can be transported separately and then spliced ​​at the installation site, solving the pain points of difficult, costly, and easily damaged transportation of ultra-large integrated panels; it allows for flexible combination of different numbers of sub-panels according to the size and thermal requirements of photovoltaic modules, achieving platform modularization and size serialization, thus broadening the application range; the splicing design allows for differentiated optimization of different sub-panel areas. For example, a sub-plate with a denser flow channel design can be used below the hot spot area of ​​the corresponding photovoltaic cell, while the edge area adopts a standard design, thereby achieving precise thermal management and optimal material cost configuration. If a part of the collector plate (a sub-plate) is damaged due to an accident, only the damaged module can be replaced or repaired, without replacing the entire collector plate, which greatly reduces the later maintenance costs and time.

[0035] Optionally, the water inlet ends of the two sub-plates each form a water inlet 1, located at the beginning of the main inlet channel. This interface serves as the main inlet for the cooling medium, responsible for smoothly introducing the low-temperature medium into the entire biomimetic flow channel system. The water outlet ends of the two sub-plates each form a water outlet 4, located at the end of the main outlet channel. All the medium heated in the flow channel gathers and flows out here. The water inlet 1 and water outlet 4 are arranged opposite each other. The water inlet ends of the two sub-plates are welded together by a T-junction to form a single water inlet 1, and the water outlet 4 is arranged similarly. This inlet-outlet opposing layout is key to achieving the longest flow path and the largest heat exchange area in the flow channel. It ensures that the cooling medium can flow completely from one side of the plate to the other, covering the entire heat collection area without dead angles, thereby maximizing heat exchange efficiency. At the same time, this symmetrical layout also facilitates the arrangement of external pipelines during system integration, making the pipeline routing neat and standardized. There is a junction box 3 on each side of the heat collection plate body. This distributed layout, rather than a centralized single-point layout, is based on its important function of serving the rear photovoltaic modules. Each junction box 3 is responsible for collecting the current generated by the photovoltaic cells in its vicinity. Through internal bypass diodes and other functions, it provides circuit protection in cases of localized shading or faults, reducing the risk of hot spot effects. The dual-sided distribution design shortens the wiring distance of the battery string busbars, reducing internal resistance and power loss, and improving photovoltaic power generation efficiency. Junction boxes 3 are typically made of high-strength, weather-resistant engineering plastics, achieving an IP67 or higher protection rating, ensuring long-term resistance to harsh outdoor environments (such as rain, ultraviolet radiation, high temperature and humidity).

[0036] Optionally, the collector panel body can be integrated with the photovoltaic layer using structural adhesive. This design not only ensures efficient heat transfer, transferring waste heat generated by the photovoltaic layer to the collector panel, but also protects the photovoltaic layer from damage to the fragile photovoltaic cells, while also ensuring structural stability and process compatibility.

[0037] The above-described embodiments are merely a few specific examples of this utility model. However, the embodiments of this utility model are not limited thereto, and any variations that can be conceived by those skilled in the art should fall within the protection scope of this utility model.

Claims

1. A photovoltaic-thermal integrated panel with a back heat collector, characterized in that, Includes a heat collection plate body, wherein a flow channel (2) is formed on one side of the heat collection plate body, the flow channel (2) is in the shape of a biomimetic blood vessel, the flow channel (2) includes a main inlet channel, a multi-level branch channel and a main outlet channel connected in sequence, the multi-level branch channel extending out from the main inlet channel in stages.

2. The photovoltaic-thermal integrated panel back heat collector as described in claim 1, characterized in that, The flow channel (2) is formed by inflation.

3. The photovoltaic-thermal integrated panel back heat collector as described in claim 1, characterized in that, The main inlet channel and the main outlet channel are symmetrically distributed, and the cross-sectional shape of the main inlet channel and the main outlet channel is circular with a diameter of 8 mm to 10 mm.

4. The back heat collector of the photovoltaic-thermal integrated panel as described in claim 1, characterized in that, The main inlet channel, multi-level branch channels, and the main outlet channel are connected at the joints of adjacent channels with smooth transitions.

5. The photovoltaic-thermal integrated panel back heat collector as described in claim 1, characterized in that, The multi-level branch channels converge at their ends or connect independently to the main outflow channel.

6. The back heat collector of the photovoltaic-thermal integrated panel as described in claim 1, characterized in that, The density of branch channels in the photovoltaic cell heat concentration area of ​​the heat collector plate is greater than that in the area with uniform heat distribution.

7. The photovoltaic-thermal integrated panel back heat collector as described in claim 1, characterized in that, The heat collection plate body includes two sub-plates spliced ​​together as one piece. The connection between the two sub-plates has a connecting surface formed by bending. The two sub-plates are connected by fixing the two connecting surfaces.

8. The photovoltaic-thermal integrated panel back heat collector as described in claim 7, characterized in that, The water inlet of each of the two sub-plates forms a water inlet (1), which is located at the beginning of the main inlet channel. The water outlet of each of the two sub-plates forms a water outlet (4), which is located at the end of the main outlet channel. The water inlet (1) and the water outlet (4) are arranged opposite to each other. There is a junction box (3) on each side of the heat collection plate body.

9. The back heat collector of the photovoltaic-thermal integrated panel as described in claim 1, characterized in that, The heat collection plate body is integrated with the photovoltaic layer through structural adhesive.

Images