Photovoltaic panel cooling device for strengthening convective heat transfer

Abstract

The invention provides a photovoltaic panel cooling device for strengthening convective heat transfer, which comprises photovoltaic panels, the photovoltaic panels are mutually laid and connected, the edges of the adjacent photovoltaic panels are oppositely provided with air guide blades, and an airflow channel is formed between the adjacent air guide blades; the short sides of the adjacent photovoltaic panels are tightly combined, connected and mounted, and the long sides of the photovoltaic panels are provided with air guide blades; the adjacent photovoltaic panels are connected through a fixing device; a sealing gasket is arranged at the joint between the fixing device and the photovoltaic panel, and the sealing gasket is made of a polytetrafluoroethylene material. And the back surface of the photovoltaic panel is provided with a back plate sealing rubber strip. According to the photovoltaic panel cooling device, hot pressure generated by heat dissipation of the back face of the photovoltaic panel is used as circulating power, stable upflow can be generated through the flow guiding device when the sun irradiates, and therefore enhanced convective heat transfer of the back face of the photovoltaic panel can be achieved, the temperature of the photovoltaic panel is reduced, and the photovoltaic power generation efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic power generation, and particularly relates to a photovoltaic panel cooling device for enhancing convective heat transfer. Background Art

[0002] In recent years, significant progress has been made in photovoltaic power generation technology, and its proportion in the global energy structure has been continuously increasing. However, during the power generation process of photovoltaic panels, the problem of excessively high backplane temperature has gradually emerged, seriously affecting the power generation efficiency and becoming one of the key factors restricting the further development of the photovoltaic industry. As an important part of photovoltaic modules, the backplane not only plays a role in protecting the battery cells but also has an important impact on the heat dissipation performance of photovoltaic modules. When the backplane temperature is too high, it will lead to a decline in the performance of photovoltaic cells, thereby reducing the power generation efficiency of photovoltaic panels. According to the experimental research by Liang Zhennan of Guangdong University of Technology on the influence of backplane materials on the performance of solar cell modules, for every 1°C increase in the temperature of photovoltaic modules, their power generation efficiency decreases by approximately 0.35%-0.5%. This means that in a high-temperature environment, the power generation efficiency of photovoltaic panels may be significantly reduced, thus affecting the overall revenue of photovoltaic power generation systems. In addition, excessively high backplane temperature may also lead to a shortened service life of photovoltaic modules and an increase in maintenance costs.

[0003] According to the research reports released by industry authoritative institutions, globally, approximately 60%-70% of photovoltaic power stations face the problem of excessively high backplane temperature during operation. Especially in some high-temperature and high-radiation areas, such as desert areas, tropical regions, and some subtropical regions, this problem is more prominent, and the proportion of photovoltaic power stations with excessively high backplane temperature can reach more than 80%. In addition, high temperature will also increase the heat of internal electronic components in photovoltaic modules, leading to an increase in the failure rate of electronic components and shortening the service life of photovoltaic modules.

[0004] It is retrieved that the utility model patent with the application number CN202420896183.9 discloses a photovoltaic module with automatic cooling. It consists of systems such as a water spraying system, a water circulation system, a rainwater recovery water tank, and a cooling fan. By spraying water on the photovoltaic surface and continuing to ventilate with the fan, the temperature of the photovoltaic panel can be reduced, and the dependence on external water sources can be reduced and the effect of continuously cooling the photovoltaic panel can be achieved. The disadvantages of this utility model are that it requires the start of the circulation water pump and the cooling fan during operation, and it also consumes some water resources. At the same time, it only needs to set up equipment such as brackets and water tanks, and the equipment size is large, which is not conducive to promotion.

[0005] Search shows that the invention patent with the application number CN202010670487.X discloses an efficient heat-dissipating solar power generation device. The device includes a body, in which there is an adjustment cavity. Above the adjustment cavity is a moving cavity, and on the right side of the moving cavity is a heat absorption cavity. In the adjustment cavity, there is an adjustment device for controlling and changing the light. The adjustment device includes a main motor fixedly installed on the lower side wall of the adjustment cavity. The main motor is power-connected to a motor shaft, and an active gear is fixedly arranged on the motor shaft. The lower side wall of the adjustment cavity is rotationally connected with a moving rotating shaft and a lifting rotating shaft. In the heat absorption cavity, there is a light-concentrating device for heat absorption and cooling. Above the body is a cooling device for concentrating sunlight. This device can collect sunlight, increase the light energy absorption of the photovoltaic panel, cool the photovoltaic panel, ensure that the photovoltaic panel is at an appropriate temperature, and increase the photoelectric conversion efficiency. The disadvantages of this invention are that the main motor and air pump of the adjustment device need to be started during operation, consuming electric power resources. At the same time, the device system is too complex and the equipment is large, which is not conducive to popularization.

[0006] Search shows that the utility model patent with the application number CN202420916304.1 discloses a frameless solar PVT module. It mainly consists of a transparent surface layer, a photovoltaic cell layer, a photovoltaic backplane layer, a heat exchange layer, purlins, fixing clamps, and a junction box. There is an adhesive layer between each layer. After the PVT module layers are stacked, purlins and fixing clamps are installed, and finally the battery box is installed. The purlins and fixing clamps fix each layer of the PVT module. The disadvantage of this utility model is that the PVT technology enhances the heat effect of the photovoltaic panel through the heat medium cycle and is often used in combination with a heat pump system, which is not applicable to projects without heat recovery requirements.

[0007] To solve the above problem of cooling the backplane of the photovoltaic panel, the present invention provides a photovoltaic panel cooling device that enhances convective heat transfer, which can utilize the thermal pressure of the inlet and outlet air vents to form a stable upward air flow. The inlet air vent section can enhance the convective heat transfer of the photovoltaic backplane and achieve the reduction of the backplane temperature. Summary of the Invention

[0008] In view of the problems in the prior art, the present invention proposes a photovoltaic panel cooling device that enhances convective heat transfer.

[0009] To achieve the above object, the present invention provides the following technical solutions:

[0010] A photovoltaic panel cooling device that enhances convective heat transfer includes a photovoltaic panel. The photovoltaic panels are laid and connected to each other. Air guide vanes are oppositely arranged at the edges of adjacent photovoltaic panels, and an air flow channel is formed between adjacent air guide vanes.

[0011] As a further improvement of this solution, the short sides of adjacent photovoltaic panels are closely combined and connected, and air guide vanes are arranged on the long sides of the photovoltaic panels.

[0012] As a further improvement of this solution, adjacent photovoltaic panels are connected through a fixing device.

[0013] As a further improvement of this solution, the fixing device is any one of a screw-type fixing device, a spring-type fixing device, and a bayonet-type fixing device.

[0014] As a further improvement of this solution, a sealing gasket is provided at the connection between the fixing device and the photovoltaic panel, and the sealing gasket material is selected from polytetrafluoroethylene material.

[0015] As a further improvement of this solution, a backplane sealing strip is provided on the back of the photovoltaic panel. The backplane sealing strip material is selected from polytetrafluoroethylene material, is centrally arranged in the middle position of the photovoltaic panel, and is installed by means of adhesive bonding.

[0016] As a further improvement of this solution, the photovoltaic panels are laid and connected to each other and the whole has a slope; a rainwater recovery trough is provided at the low foot of the slope.

[0017] As a further improvement of this solution, the air guide vanes are made of high-transparency, aging-resistant, and flame-retardant PRF.

[0018] As a further improvement of this solution, after the air guide vanes are installed, a closed water flow channel can be formed on both sides of the photovoltaic panel; the air guide vanes are sealed with a transparent sealant.

[0019] As a further improvement of this solution, the net width of the air flow channel is not less than 50 mm.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention uses the thermal pressure generated by the heat dissipation on the back of the photovoltaic panel as the circulation power. When the sun shines, a stable upward air flow can be generated through the air guide vanes, so as to realize the enhanced convective heat transfer on the back of the photovoltaic panel, thereby reducing the temperature of the photovoltaic panel and improving the photovoltaic power generation efficiency. After the device of the present invention is installed, the heat below the photovoltaic panel can be effectively dissipated, and the temperature distribution is more reasonable, which helps to improve the working efficiency and service life of the photovoltaic panel. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention will be further described below with reference to the drawings.

[0022] Figure 1 It is a schematic side view structure diagram of the whole of the present invention;

[0023] Figure 2 It is a schematic top view structure diagram of the whole of the present invention;

[0024] Figure 3 It is a schematic diagram of the auxiliary calculation principle of the photovoltaic panel cooling device of the present invention;

[0025] Figure 4 It is a marked diagram of the calculation principle of the photovoltaic panel cooling device of the present invention;

[0026] Figure 5 Schematic cross-sectional structure diagram of the rainwater recovery tank installation structure of the present invention;

[0027] Figure 6 Schematic plan view of the horizontal combination installation of two photovoltaic panels of the present invention;

[0028] Figure 7 Schematic structure diagram of three fixing methods of the fixing device of the present invention;

[0029] Figure 8 Temperature change diagram of the photovoltaic panel without the cooling device of the present invention;

[0030] Figure 9 Temperature change diagram of the photovoltaic panel installed with the cooling device of the present invention.

[0031] In the figure, the markings are as follows: 1. Photovoltaic panel; 2. Backplane sealing strip; 3. Air flow channel; 4. Air guiding vane; 5. Sealing gasket; 6. Fixing device; 6-1. Screw-type fixing device; 6-2. Spring-type fixing device; 6-3. Bayonet-type fixing device; 7. Rainwater recovery tank. Detailed implementation manners

[0032] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0033] Embodiment

[0034] As Figures 1-3 shown, this embodiment provides a photovoltaic panel cooling device for enhancing convective heat transfer, including a photovoltaic panel 1, the photovoltaic panels 1 are laid and connected to each other, air guiding vanes 4 are relatively arranged at the edges of adjacent photovoltaic panels 1, and an air flow channel 3 is formed between the adjacent air guiding vanes 4. The short sides of adjacent photovoltaic panels 1 are closely combined and connected for installation, and air guiding vanes 4 are arranged on the long sides of the photovoltaic panels 1.

[0035] Adjacent photovoltaic panels 1 are connected by a fixing device 6. The fixing device 6 is any one of a screw-type fixing device 6-1, a spring-type fixing device 6-2, and a bayonet-type fixing device 6-3.

[0036] A sealing gasket 5 is provided at the connection between the fixing device 6 and the photovoltaic panel 1, and the material of the sealing gasket 5 is selected as polytetrafluoroethylene material.

[0037] On the back of the photovoltaic panel 1, there is a backplane sealing strip 2. The material of the backplane sealing strip 2 is selected as polytetrafluoroethylene material, which is centered at the middle position of the photovoltaic panel 1 and installed by means of adhesive bonding. After the photovoltaic panels 1 are laid and connected to each other, the whole has a slope; a rainwater recovery groove is provided at the low foot of the slope. The air guide vanes 4 are made of high-transparency, aging-resistant and flame-retardant PRF. After the air guide vanes 4 are installed, a closed water flow channel can be formed on both sides of the photovoltaic panel 1; the air guide vanes are sealed with transparent sealant. The net width of the air flow channel 3 is not less than 50 mm.

[0038] The specific working principle is as follows, see Figure 3 、 Figure 4 , according to the principle of hydrostatics, the pressure difference inside and outside the air inlet of the photovoltaic panel is:

[0039] △P b =P b ’-P b =(P a ’-ghρ n )-(P a -ghρ w )=△P a +gh(ρ w -ρ n )

[0040] In the formula: △P a、 △P b —The pressure difference inside and outside the air inlet, Pa; P a —The static pressure outside the air inlet, Pa; P a ’—The static pressure inside the air inlet, Pa; P b —The static pressure outside the exhaust port, Pa; P b ’—The static pressure inside the exhaust port, Pa; g—The acceleration of gravity, m / s 2 ; h—The height difference between the air inlet and the exhaust port, m; ρ n —The air density inside the device, kg / m 3 ; ρ w —The air density outside the device, kg / m 3 .

[0041] It can be seen that even when △P a =0, there is still △P b >0.

[0042] △P b +(-△P a )=△P b +|△P a |=gh(ρ w -ρ n )

[0043] gh(ρ w-ρ n ) is called thermal pressure, and the factors causing it are the height difference between the inlet and outlet vents and the temperature difference between the inlet and outlet vents.

[0044] When there is only the action of thermal pressure, first assume the position of the neutral plane, and the static pressure of the remaining ventilation openings can be calculated.

[0045] The static pressure of the air inlet at the bottom of the photovoltaic panel is: P ax = p 0x - h 1 (ρ w - ρ n )g = - h 1 (ρ w - ρ n )g.

[0046] The static pressure of the air outlet at the top of the air guide vane is P bx = p 0x + h 2 (ρ w - ρ n )g = h 2 (ρ w - ρ n )g.

[0047] h 1 、h 2 —The distances from the air vents a and b to the neutral plane, m. p 0x —The static pressure of the neutral plane, take 0. The pressure above the neutral plane is positive pressure, which is the air outlet; the pressure below the neutral plane is negative pressure, which is the air inlet.

[0048] If the assumed position of the neutral plane is different, the calculated area distribution of each air vent will be different. Under the action of only thermal pressure, the areas of the air inlet and outlet are respectively:

[0049] Air inlet:

[0050] Air outlet:

[0051] In the formula, ΔP a 、ΔP a —The internal and external pressure differences of the air vents a and b, Pa;

[0052] F a —The area of the air inlet, m 2 ;

[0053] F b —The area of the air outlet, m 2 ;

[0054] G a 、G b —The flow rates of the air vents a and b, kg / s;

[0055] μ a 、 μ b — Flow coefficient of air inlets a and b;

[0056] ρ w — Air density outside the device, kg / m 3 ;

[0057] ρ p — Air density at the exhaust air temperature, kg / m 3 ;

[0058] ρ np — Air density at the average temperature, kg / m 3 ;

[0059] h 1 、 h 2 — Distances from air inlets a and b to the neutral plane, m;

[0060] g— Acceleration due to gravity, m / s 2 .

[0061] According to the air volume balance equation G a = G b , approximately assuming μ a = μ b , ρ w = ρ p , the above formula can be simplified to:

[0062] (F a / F b ) 2 = h 2 / h 1

[0063] According to the above formula, it can be seen that the ratio of the inlet and exhaust air vent areas changes with the position of the neutral plane. When the neutral plane moves upward (i.e., increasing h 1 and decreasing h 2 ), the exhaust air vent area increases and the inlet air vent area decreases; when the neutral plane moves downward, the opposite occurs. In the design of the photovoltaic panel cooling device for enhancing convective heat transfer, the position of the neutral plane can be artificially set, and as long as the areas of the inlet and exhaust windows are changed, the position of the neutral plane will change accordingly.

[0064] To verify the cooling effect of the photovoltaic panel cooling device for enhancing convective heat transfer described in the present invention, detailed simulation calculations were carried out using fluent software.

[0065] Model parameters: The specifications of the photovoltaic panel are 1132mm * 2382mm, the thickness of the photovoltaic panel is negligible, h 2 is 5mm, and the size of the air flow channel is 50mm.

[0066] Fa = (1132 mm + 50 mm) * 2382 mm = 2.82 m 2 ,

[0067] Set h 1 = 150 mm;

[0068] The width of the device air outlet can be calculated

[0069] The data calculated from the above model parameters were imported into fluent software for detailed simulation calculations, and the results are as Figure 8 , Figure 9 shown.

[0070] In the absence of the structure described in the present invention, the temperature at point 1 is about 25 degrees, the temperature at point 2 is about 30 degrees, and for points 3 and 4 close to the underside of the solar panel, the temperatures are as high as about 100 degrees and 115 degrees respectively.

[0071] After installing the photovoltaic panel cooling device for enhanced convective heat transfer of the present invention, the temperatures at points 1 and 2 rise to about 28 degrees and 35 degrees respectively. For points 3 and 4 close to the underside of the solar panel, they drop from about 100 degrees and 115 degrees respectively to about 58 degrees and 80 degrees, and the cooling effect is very obvious.

[0072] This indicates that the heat starts to flow upward and the overall temperature distribution becomes more uniform. Secondly, the local temperature drops significantly, and the most remarkable is the temperature change at points 3 and 4, which drop from about 100 degrees and 115 degrees respectively to about 58 degrees and 80 degrees, and the cooling effect is very obvious.

[0073] The present invention utilizes the thermal pressure generated by the heat dissipation on the back of the photovoltaic panel as the circulation power. When the sun shines, a stable upward air flow can be generated through the air guiding blades, thereby realizing enhanced convective heat transfer on the back of the photovoltaic panel, reducing the temperature of the photovoltaic panel, and improving the photovoltaic power generation efficiency. After installing the device of the present invention, the heat below the photovoltaic panel can be effectively dissipated, and the temperature distribution becomes more reasonable, which helps to improve the working efficiency and service life of the photovoltaic panel.

[0074] The above content is only an example description of the structure of the present invention. Those skilled in the art of this technology make various modifications or supplements or use similar methods to replace the specific embodiments described, as long as they do not deviate from the structure of the present invention or exceed the scope defined by this claim book, they should fall within the protection scope of the present invention.

Claims

1. A photovoltaic panel cooling device for enhanced convective heat transfer, comprising photovoltaic panels (1), wherein the photovoltaic panels (1) are laid and connected to each other, and characterized in that: Air guide blades (4) are arranged opposite to each other at the edges of adjacent photovoltaic panels (1), and an air flow channel (3) is formed between the adjacent air guide blades (4).

2. A photovoltaic panel cooling device with enhanced convective heat transfer according to claim 1, characterized in that: The short sides of adjacent photovoltaic panels (1) are tightly combined, connected and installed, and the long sides of the photovoltaic panels (1) are provided with air guide blades (4).

3. The photovoltaic panel cooling device with enhanced convective heat transfer according to claim 1, characterized in that: Adjacent photovoltaic panels (1) are connected via a fixing device (6).

4. The photovoltaic panel cooling device with enhanced convective heat transfer according to claim 3, characterized in that: The fixing device (6) is any one of a screw-type fixing device (6-1), a spring-type fixing device (6-2), and a bayonet-type fixing device (6-3).

5. The photovoltaic panel cooling device with enhanced convective heat transfer according to claim 3, characterized in that: A sealing gasket (5) is provided at the connection between the fixing device (6) and the photovoltaic panel (1), and the sealing gasket (5) is made of polytetrafluoroethylene material.

6. The photovoltaic panel cooling device with enhanced convection heat transfer according to claim 1, characterized in that: A back plate sealing strip (2) is provided on the back of the photovoltaic panel (1). The back plate sealing strip (2) is made of polytetrafluoroethylene material and is centrally arranged in the middle of the photovoltaic panel (1) and is installed by means of adhesive stickers.

7. The photovoltaic panel cooling device with enhanced convection heat transfer according to claim 1, characterized in that: The photovoltaic panels (1) are laid and connected to each other so that the whole has a slope; a rainwater recovery trough (7) is provided at the lower foot of the slope.

8. The photovoltaic panel cooling device with enhanced convection heat transfer according to claim 1, characterized in that: The air guide blades (4) are made of highly light-transmitting, ageing-resistant and flame-retardant PRF.

9. The photovoltaic panel cooling device with enhanced convective heat transfer according to claim 1, characterized in that: After the air guide blades (4) are installed, closed water flow channels can be formed on both sides of the photovoltaic panel (1); transparent sealant is used to seal between the air guide blades.

10. The photovoltaic panel cooling device with enhanced convection heat transfer according to claim 1, characterized in that: The net width of the air flow channel (3) is not less than 50 mm.

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