A lightweight solar collector based on a microchannel composite structure

Abstract

This application discloses a lightweight solar collector based on a microchannel composite structure, comprising a heat transfer layer and multiple flow channels. One side of the heat transfer layer is attached to the back of the photovoltaic module, and the other side of the heat transfer layer contacts the flow channels. The heat transfer layer transfers heat from the photovoltaic module to the fluid within the flow channels. The inlet of the flow channels is connected to an inlet manifold, and the outlet of the flow channels is connected to an outlet manifold. By varying the cross-sectional dimensions of the flow channels along the centerline, the heat absorption efficiency of the photovoltaic module corresponding to each flow channel tends to be uniform when the fluid flows within the channels. The beneficial effects of this application are: by using flow channels with varying cross-sectional dimensions along the centerline, the heat absorption efficiency of the photovoltaic module tends to be uniform when the fluid flows within the channels, allowing the photovoltaic module along the flow channel direction to receive balanced and effective cooling. This results in more uniform heating of the photovoltaic module, avoiding the efficiency reduction caused by uneven heating, and improving the stability and reliability of the system operation.

Description

Technical Field

[0001] This application relates to the field of solar collectors, and in particular to a lightweight solar collector based on a microchannel composite structure. Background Technology

[0002] Photovoltaic collectors are the core components of photovoltaic (PV) thermal systems. One of their main functions is to effectively reduce the operating temperature of PV modules through convective heat transfer. While generating electricity under sunlight, PV modules also produce a significant amount of waste heat, causing their own temperature to rise. This leads to a decrease in power generation efficiency and accelerated aging. Photovoltaic collectors, through the flow of cooling fluid within their internal channels, continuously remove heat from the back of the PV modules, thereby maintaining the modules within their efficient operating temperature range and ensuring their output power and lifespan.

[0003] In traditional photovoltaic (PV) collectors, cooling fluid flows from the inlet to the outlet of a single channel. As the cooling fluid continuously absorbs heat during its flow, its temperature gradually increases along the channel, resulting in significant differences in heat exchange capacity at different locations within the same channel. The inlet has the lowest cooling fluid temperature, the largest temperature difference with the PV module, the highest heat exchange intensity, and the best cooling effect. Conversely, the outlet has a significantly higher cooling fluid temperature, the smallest temperature difference with the PV module, the lowest heat exchange intensity, and a poorer cooling effect, causing the PV module temperature near the outlet to be significantly higher than at the inlet. This uneven cooling along the same channel leads to a decrease in overall heat exchange efficiency and uneven heating of the PV modules, affecting the stability and reliability of the system. Therefore, a new solution is urgently needed to address these issues. Utility Model Content

[0004] The purpose of this application is to provide an automatic material lifting mechanism for molds that can solve at least one of the defects in the above-mentioned background art.

[0005] To achieve at least one of the above objectives, this application provides a lightweight solar collector based on a microchannel composite structure, including a heat transfer layer and multiple flow channels; one side of the heat transfer layer is attached to the back of a photovoltaic module, and the other side of the heat transfer layer is in contact with the flow channels, wherein the heat transfer layer transfers heat from the photovoltaic module to the fluid within the flow channels; the inlet of the flow channels is connected to an inlet manifold, and the outlet of the flow channels is connected to an outlet manifold; by varying the cross-sectional dimensions of the flow channels along the centerline, the heat absorption efficiency of the various regions of the photovoltaic module corresponding to the flow channels tends to be consistent when the fluid flows within the flow channels.

[0006] Preferably, the cross-sectional shape of the flow channel is rectangular.

[0007] Preferably, the cross-sectional width of the flow channel increases uniformly from the inlet to the outlet.

[0008] Preferably, the angle between the sidewall of the flow channel and the axis is in the range of 1-3°.

[0009] Preferably, the flow channel includes a first flow channel and a second flow channel; the first flow channel and the second flow channel are spaced apart and arranged in opposite directions, the inlet end of the first flow channel is aligned with the outlet end of the second flow channel, and the outlet end of the first flow channel is aligned with the inlet end of the second flow channel.

[0010] Preferably, the heat transfer layer includes a plate segment and a plurality of rib segments, the plate segment and the rib segments being integrally connected; one side of the plate segment is attached to the back of the photovoltaic module, and the other side is attached to the top surface of the flow channel and connected to the rib segments; both sides of the rib segments are attached to one side of the first flow channel and one side of the second flow channel.

[0011] Preferably, the cross-sectional shape of the rib segment is rectangular.

[0012] Preferably, the width of the rib segment is 0.5-2 times the minimum cross-sectional width of the flow channel.

[0013] Preferably, a heat insulation layer is provided on the bottom surface of the flow channel.

[0014] Preferably, the heat transfer layer is a fluid medium.

[0015] Compared with the prior art, the beneficial effects of this application are as follows: In the technical solution of this application, the flow channel with varying cross-sectional dimensions along the centerline allows the fluid to flow within the channel, making the heat absorption efficiency of each region of the photovoltaic module more uniform. This enables the photovoltaic module to receive balanced and effective cooling along the flow channel direction, resulting in more uniform heating of the photovoltaic module. This avoids the decrease in photovoltaic module efficiency caused by uneven heating and improves the stability and reliability of the system operation. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the overall structure of this utility model.

[0017] Figure 2 This is a schematic diagram of the first and second flow channels of this utility model.

[0018] Figure 3 This is a schematic diagram of the heat transfer layer of this utility model.

[0019] Figure 4 This is a cross-sectional schematic diagram of the overall structure of this utility model.

[0020] In the diagram: Flow channel 1, first flow channel 110, second flow channel 120, heat transfer layer 2, plate segment 210, rib segment 220, thermal insulation layer 3. Detailed Implementation

[0021] The present application will be further described below with reference to specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0022] In the description of this application, it should be noted that the terms "center", "lateral", "longitudinal", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., which indicate the orientation and positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application 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, and should not be construed as limiting the specific protection scope of this application.

[0023] It should be noted that the terms "first," "second," etc., in the specification and claims of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0024] The terms “comprising” and “having”, and any variations thereof, in the specification and claims of this application are intended to cover non-exclusive inclusion, for example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or device.

[0025] A preferred embodiment of this application, such as Figure 1 and Figure 2 As shown, a lightweight solar collector based on a microchannel composite structure includes a heat transfer layer 2 and multiple flow channels 1. One side of the heat transfer layer 2 is attached to the back of a photovoltaic module (not shown), and the other side of the heat transfer layer 2 is in contact with the flow channels 1. The heat transfer layer 2 transfers the heat of the photovoltaic module to the fluid in the flow channels 1. The inlet of the flow channel 1 is connected to an inlet manifold (not shown), and the outlet of the flow channel 1 is connected to an outlet manifold (not shown). By varying the cross-sectional size of the flow channel 1 along the centerline, the heat absorption efficiency of each region of the photovoltaic module corresponding to the flow channel 1 tends to be consistent when the fluid flows in the flow channel 1.

[0026] It should be understood that one side of the heat transfer layer 2 is in close contact with the back of the photovoltaic module. Since the temperature of the heat transfer layer 2 is lower than that of the photovoltaic module, the photovoltaic module transfers heat to the heat transfer layer 2. The other side of the heat transfer layer 2 is in contact with the flow channel 1. The fluid in the flow channel 1 is always in motion, so the temperature is kept in a low range. Since the heat transfer layer 2 absorbs the heat from the photovoltaic module, the temperature of the heat transfer layer 2 is higher than that of the fluid in the flow channel 1. Therefore, the heat transfer layer 2 further transfers heat to the fluid in the flow channel 1. After the fluid enters the flow channel 1 from the inlet manifold, it moves along the flow channel 1, absorbs the heat transferred from the heat transfer layer 2 along the way, gradually heats up, and finally collects in the outlet manifold for discharge. By continuously inputting the low-temperature fluid, the photovoltaic module is continuously cooled.

[0027] Understandably, if the cross-sectional dimensions of channel 1 are constant, the fluid temperature at the inlet of channel 1 is the lowest, and the temperature difference between the fluid and the heat transfer layer 2 and the photovoltaic module is the maximum. At this point, the fluid's heat exchange capacity is strongest, and it absorbs more heat within the same contact time, resulting in the best cooling effect for the photovoltaic module in this area. Conversely, at the outlet of channel 1, the fluid has already absorbed a significant amount of heat during its passage through channel 1, resulting in the highest fluid temperature and the minimum temperature difference between the fluid and the heat transfer layer 2 and the photovoltaic module. At this point, the fluid's heat exchange capacity is weaker, and it absorbs less heat within the same contact time. Consequently, the cooling effect for the photovoltaic module in this area decreases significantly, leading to uneven heating of the photovoltaic module and affecting the stability and reliability of the system. Therefore, by varying the cross-sectional dimensions of channel 1 along its centerline, the heat absorption efficiency of the fluid in each area of ​​the photovoltaic module within channel 1 can be made more consistent, which can significantly improve the stability and reliability of the system.

[0028] It should also be noted that the diameters of the inlet and outlet manifolds are much larger than the diameter of flow channel 1, ensuring that the flow rate in each flow channel 1 is essentially equal. When the manifold diameter is too small, the flow channel 1 near the manifold inlet will receive most of the flow, while the flow channel 1 further back will receive almost no fluid, resulting in severely uneven heat exchange. When the manifold diameter is large enough, its flow velocity decreases, which can create a uniform pressure distribution along the entire length of the manifold, ensuring that each flow channel 1 receives an essentially equal flow rate.

[0029] It is also understandable that if the photovoltaic module area is large, there can be multiple inlet and outlet manifolds, each corresponding to a portion of flow channel 1, for group cooling, thereby avoiding uneven flow distribution in flow channel 1 due to excessively long manifold sections.

[0030] The cross-sectional shape of the flow channel 1 affects the heat exchange area and is one of the most important factors affecting the cooling effect. A preferred embodiment of this application is as follows: Figure 2 As shown, the cross-sectional shape of flow channel 1 is rectangular.

[0031] It should be noted that, for the same cross-sectional area, a rectangular cross-section has a larger perimeter than a circular cross-section, meaning that the flow channel 1 has a larger contact area with the heat transfer layer 2, which translates to a larger heat exchange area. Under constant conditions, the heat exchange area is directly proportional to the heat exchange efficiency. A larger heat exchange area results in a higher heat exchange efficiency compared to a circular cross-section, thus improving the cooling efficiency. Furthermore, the manufacturing process of the rectangular cross-section flow channel 1 is relatively simple, and its performance is more reliable.

[0032] Understandably, the four corners of the rectangular cross-section help to reduce the thickness of the thermal boundary layer, further increasing the heat exchange efficiency between the fluid in the flow channel 1 and the heat transfer layer 2, thus enhancing the cooling effect of the photovoltaic module.

[0033] Changes in the cross-sectional dimensions of flow channel 1 will lead to changes in flow velocity and heat exchange area. A preferred embodiment of this application, such as... Figure 2 As shown, the cross-sectional width of flow channel 1 increases uniformly from the inlet to the outlet.

[0034] It should be understood that the cross-sectional width of channel 1 increases uniformly from the inlet to the outlet, while the side area of ​​channel 1 remains constant. However, the area of ​​the top surface of channel 1 gradually increases. Due to the gradual increase in the area of ​​the top surface of channel 1, the heat exchange area closer to the inlet is smaller, while the heat exchange area closer to the outlet is larger. Therefore, when the cross-sectional dimensions of channel 1 remain constant, the heat exchange efficiency at the inlet is much higher than that at the outlet. When the cross-sectional width of channel 1 increases uniformly from the inlet to the outlet, the heat exchange efficiency at the inlet and outlet is balanced due to the gradual increase in the heat exchange area. The temperature difference between the inlet and heat transfer layer 2 of channel 1 is large, but the heat exchange area is small. Conversely, the temperature difference between the outlet and heat transfer layer 2 is small, but the heat exchange area is large. Overall, this results in a more balanced heat exchange efficiency across different regions, leading to a more balanced cooling effect across different regions of the photovoltaic module.

[0035] It should also be noted that the flow rate of channel 1 does not change. Therefore, when the cross-sectional area is larger, the flow velocity at this location will be slower, allowing the fluid more time to exchange heat with the heat transfer layer 2. Thus, the fluid velocity is faster closer to the inlet end of channel 1 and slower closer to the outlet end of channel 1, making the heat exchange time at the inlet end of channel 1 shorter than that at the outlet end of channel 1. This further reduces the difference in heat exchange efficiency between the inlet end of channel 1 and the outlet end of channel 1 with respect to the heat transfer layer 2, making the heat exchange efficiency of each region more consistent.

[0036] When the cross-sectional width of the flow channel 1 increases uniformly from the inlet to the outlet, the increasing gradient will affect the fitting efficiency between the flow channel 1 and the heat transfer layer 2. A preferred embodiment of this application is as follows... Figure 2As shown, the angle between the sidewall of flow channel 1 and the axis ranges from 1 to 3°.

[0037] It should be understood that if the angle between the sidewall of the flow channel 1 and the axis is less than 1°, although the fluid flow is very smooth and the pressure change is gradual, the heat exchange efficiency equalization effect along the flow channel 1 is not obvious; while if the angle between the sidewall of the flow channel 1 and the axis is greater than 3°, the fluid may tend to leave the wall due to inertia, resulting in poor heat exchange. Therefore, in this embodiment, the angle between the sidewall of the flow channel 1 and the axis is preferably in the range of 1-3°.

[0038] Since the cross-sectional width of flow channel 1 increases uniformly from the inlet to the outlet, flow channel 1 needs to be arranged in a close-packed configuration to achieve a larger cooling range. A preferred embodiment of this application is as follows: Figure 1 and Figure 2 As shown, the flow channel 1 includes a first flow channel 110 and a second flow channel 120; the first flow channel 110 and the second flow channel 120 are spaced apart and arranged in opposite directions, the inlet end of the first flow channel 110 is aligned with the outlet end of the second flow channel 120, and the outlet end of the first flow channel 110 is aligned with the inlet end of the second flow channel 120.

[0039] It should be noted that the first flow channel 110 and the second flow channel 120 are exactly the same size. The shape of the flow channel 1 is trapezoidal when viewed from above. Therefore, the first flow channel 110 and the second flow channel 120 are spaced apart and set in opposite directions, so that the upper base of the trapezoid of the first flow channel 110 and the lower base of the trapezoid of the second flow channel 120 are in a straight line. This makes the flow channel 1 more dense and uniform, which greatly improves the cooling effect on the photovoltaic module.

[0040] It is understandable that if a unidirectional gradually expanding flow channel 1 is used, the gap between the inlet ends of the flow channel 1 will be too large, and the heat transfer layer 2 here will not be fully utilized. However, by using the first flow channel 110 and the second flow channel 120, which are spaced apart and arranged in opposite directions, the flow channel 1 is maximized in density on the plane, forming the largest and most effective heat exchange area, so that every area of ​​the photovoltaic module can be directly cooled by the flow channel 1.

[0041] To increase the heat exchange area, heat exchange should occur not only at the top of the flow channel 1 but also on the sides of the flow channel 1. A preferred embodiment of this application is as follows... Figure 1 , Figure 3 and Figure 4 As shown, the heat transfer layer 2 includes a plate segment 210 and multiple rib segments 220, which are integrally connected; one side of the plate segment 210 is attached to the back of the photovoltaic module, and the other side is attached to the top surface of the flow channel 1 and connected to the rib segment 220; the two sides of the rib segment 220 are attached to one side of the first flow channel 110 and one side of the second flow channel 120.

[0042] It should be understood that the plate segment 210 of the heat transfer layer 2 is attached to the back of the photovoltaic module, and absorbs the heat of the photovoltaic module into the heat transfer layer 2. Part of the heat is exchanged through the contact between the plate segment 210 and the top surface of the flow channel 1, and the other part is exchanged through the rib segment 220 connected to the plate segment 210 and the side surface of the flow channel 1.

[0043] Understandably, by setting the fin segment 220, the heat exchange area is increased from one top surface to one top surface and two sides. Furthermore, the fin segment 220 occupies a smaller volume, reducing the number of flow channels 1, but achieving more than twice the heat exchange area, thus significantly improving the heat exchange efficiency. Moreover, one side of the fin segment 220 contacts the first flow channel 110, and the other side of the fin segment 220 contacts the second flow channel 120, so that the heat exchange between the adjacent first flow channel 110 and second flow channel 120 is balanced through the fin segment 220, which can further make the cooling of various areas of the entire photovoltaic module more uniform.

[0044] The shape of the rib segment 220 should conform to the side of the flow channel 1. In a preferred embodiment of this application, such as... Figure 1 , Figure 3 and Figure 4 As shown, the cross-sectional shape of rib segment 220 is rectangular.

[0045] It should be noted that the cross-sectional shape of the rib segment 220 is a rectangle with fixed dimensions, and its width is exactly equal to the distance between adjacent first flow channels 110 and second flow channels 120. The regular rectangular cross-section makes it easier to achieve high-precision and high-efficiency production in terms of processing and forming, and the rectangular dimensions are simpler to manufacture compared to complex curves and variable cross-sections. Furthermore, the rectangular cross-section rib segment 220 can be seamlessly and well embedded between two adjacent first flow channels 110 and second flow channels 120, providing reliable assurance for heat exchange performance.

[0046] A preferred embodiment of this application, such as Figure 1 , Figure 3 and Figure 4 As shown, the width of rib segment 220 is 0.5-2 times the minimum cross-sectional width of flow channel 1.

[0047] It should be understood that if the width of the rib segment 220 is too small, the cross-sectional area will be too small, and heat cannot be effectively transferred from the plate segment 210 to the end of the rib segment 220, resulting in a decrease in the heat exchange efficiency of the rib segment 220. Insufficient heat will not be available for heat exchange through the side of the flow channel 1, thus wasting the potential heat exchange area of ​​the rib segment 220. Conversely, if the width of the rib segment 220 is too large, since the total area is constant, the number of flow channels 1 will decrease. Furthermore, an excessively wide rib segment 220 will have a larger total heat volume, and the fixed heat exchange area on the side of the flow channel 1 may not be able to absorb such a large amount of heat from the rib segment 220. The reduction in the number of flow channels 1 will also lead to a decrease in heat exchange efficiency. Therefore, in this embodiment, the width of the rib segment 220 is preferably 0.5-2 times the minimum cross-sectional width of the flow channel 1.

[0048] The top and side surfaces of flow channel 1 are in contact with heat transfer layer 2. Although the bottom surface does not participate in the heat exchange process, if the bottom surface exchanges heat with the outside, it will weaken the cooling effect of the fluid in flow channel 1 on the photovoltaic module. A preferred embodiment of this application is as follows... Figure 1 and Figure 4 As shown, a heat insulation layer 3 is provided on the bottom surface of the flow channel 1.

[0049] It should be understood that setting the thermal insulation layer 3 on the bottom surface of the flow channel 1 prevents the fluid in the flow channel 1 from further transferring heat to the outside, thus preventing heat loss. It also ensures that the fluid in the flow channel 1 only exchanges heat with the heat transfer layer 2 and is not affected by the ambient temperature below, thereby reducing the cooling effect on the photovoltaic module. Furthermore, if the thermal insulation layer 3 is not set on the bottom surface of the flow channel 1, the fluid may cause thermal damage or thermal aging risk to the equipment at the bottom after the heat exchange is heated. Therefore, setting the thermal insulation layer 3 on the bottom surface of the flow channel 1 can significantly improve the reliability and efficiency of the fluid heat exchange process in the flow channel 1.

[0050] The heat transfer layer 2 can be a solid medium or a fluid medium. A preferred embodiment of this application is as follows: Figure 4 As shown, the heat transfer layer 2 uses a fluid medium.

[0051] It should be understood that solid media have limited heat transfer capacity and poor temperature uniformity; while fluid media, due to their flowability, can quickly transfer heat from high-temperature regions to low-temperature regions through convection; and through flow and mixing, the temperature of the fluid itself can become uniform, while solid media may produce defects such as local overheating; therefore, in this embodiment, the heat transfer layer 2 preferably uses a fluid medium.

[0052] The basic principles, main features, and advantages of this application have been described above. Those skilled in the art should understand that this application is not limited to the above embodiments. The embodiments and descriptions in the specification are merely the principles of this application. Various changes and modifications can be made to this application without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claims. The scope of protection claimed by this application is defined by the appended claims and their equivalents.

Claims

1. A lightweight solar collector based on a microchannel composite structure, characterized in that: It includes a heat transfer layer and multiple flow channels; one side of the heat transfer layer is attached to the back of the photovoltaic module, and the other side of the heat transfer layer is in contact with the flow channels. The heat transfer layer transfers the heat of the photovoltaic module to the fluid in the flow channels; the inlet of the flow channels is connected to an inlet manifold, and the outlet of the flow channels is connected to an outlet manifold; by varying the cross-sectional size of the flow channels along the centerline, the heat absorption efficiency of the photovoltaic module corresponding to the flow channels tends to be consistent when the fluid flows in the flow channels.

2. The lightweight solar collector based on a microchannel composite structure as described in claim 1, characterized in that: The cross-sectional shape of the flow channel is rectangular.

3. The lightweight solar collector based on a microchannel composite structure as described in claim 2, characterized in that: The cross-sectional width of the flow channel increases uniformly from the inlet to the outlet.

4. The lightweight solar collector based on a microchannel composite structure as described in claim 3, characterized in that: The angle between the sidewall of the flow channel and the axis ranges from 1 to 3°.

5. The lightweight solar collector based on a microchannel composite structure as described in claim 3, characterized in that: The flow channel includes a first flow channel and a second flow channel; the first flow channel and the second flow channel are spaced apart and arranged in opposite directions, the inlet end of the first flow channel is aligned with the outlet end of the second flow channel, and the outlet end of the first flow channel is aligned with the inlet end of the second flow channel.

6. The lightweight solar collector based on a microchannel composite structure as described in claim 5, characterized in that: The heat transfer layer includes plate segments and multiple rib segments, the plate segments and the rib segments are integrally connected; one side of the plate segment is attached to the back of the photovoltaic module, and the other side is attached to the top surface of the flow channel and connected to the rib segments; the two sides of the rib segments are attached to one side of the first flow channel and one side of the second flow channel.

7. The lightweight solar collector based on a microchannel composite structure as described in claim 6, characterized in that: The cross-sectional shape of the rib segment is rectangular.

8. The lightweight solar collector based on a microchannel composite structure as described in claim 7, characterized in that: The width of the rib segment is 0.5-2 times the minimum cross-sectional width of the flow channel.

9. The lightweight solar collector based on a microchannel composite structure as described in any one of claims 1-8, characterized in that: A heat insulation layer is provided on the bottom surface of the flow channel.

10. The lightweight solar collector based on a microchannel composite structure as described in any one of claims 1-8, characterized in that: The heat transfer layer uses a fluid medium.

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