A solar collector based on flat-plate micro heat pipes

Abstract

This application discloses a solar collector based on flat-plate micro heat pipes, relating to the field of solar thermal utilization technology. It includes a collector housing, collector pipes, and flat-plate micro heat pipes. The collector housing is inclined and positioned on the ground. The collector pipes are disposed within the collector housing, with both ends located on opposite sides of the housing. One end of the collector pipe is a water inlet, and the other end is a water outlet. Multiple flat-plate micro heat pipes are spaced apart along the axis of the collector pipes. Each flat-plate micro heat pipe includes an evaporation section and a condensation section. The condensation section is arc-shaped and fitted around the periphery of the collector pipes, with its center located on the axis of the collector pipes. The condensation section heats the collector pipes. The evaporation section is located below the condensation section. This application improves heat transfer efficiency.

Description

Technical Field

[0001] This application relates to the field of solar thermal utilization technology, and in particular to a solar collector based on a flat plate micro heat pipe. Background Technology

[0002] Solar collectors, as highly efficient devices for utilizing solar energy, are widely used in hot water supply, heating, and power generation. With increasing global energy demand and heightened environmental awareness, the development of solar energy technology has received widespread attention. Solar collectors absorb solar radiation and convert it into heat energy, providing humanity with a clean and renewable energy solution, which is of great significance in alleviating the energy crisis and reducing environmental pollution. In this field, researchers worldwide are constantly exploring innovative designs to improve collection efficiency and reduce costs, thereby promoting the widespread adoption and application of solar energy technology.

[0003] In solar collectors (such as flat-plate collectors and evacuated tube collectors), the design of the collector tubes affects many aspects, including fluid flow, heat transfer performance, pressure loss, and installation and maintenance. Straight collector tubes offer advantages such as low flow resistance, more uniform flow, easier flow distribution control, lower manufacturing and installation costs, and convenient cleaning and maintenance. However, their heat transfer capacity is limited, and local temperature gradients can be large. Bent-back collector tubes, on the other hand, can increase fluid turbulence. The fluid mixes continuously during the bends, achieving a turbulent state, reducing the likelihood of localized overheating, resulting in a more uniform system temperature distribution and improved heat utilization. However, bent-back collector tubes have higher fluid flow resistance, are more difficult to manufacture, and are prone to scale buildup in the bends, making cleaning and maintenance more complex. Furthermore, if poorly designed, the bends can create localized low-velocity zones or vortex regions, negatively impacting heat transfer efficiency.

[0004] Therefore, how to achieve efficient heat exchange using low-cost linear heat collection tubes has become a pressing technical challenge. Summary of the Invention

[0005] To address the issue of improving heat transfer efficiency, this application provides a solar collector based on a flat-plate micro heat pipe.

[0006] This application provides a solar collector based on a flat-plate micro heat pipe, employing the following technical solution:

[0007] A solar collector based on flat-plate micro heat pipes includes a heat collection box, which is inclinedly disposed on the ground; a heat collection pipe disposed within the heat collection box, with both ends of the heat collection pipe located on both sides of the heat collection box, one end of the heat collection pipe being a water inlet and the other end being a water outlet; multiple flat-plate micro heat pipes are spaced apart along the axis of the heat collection pipe, each flat-plate micro heat pipe including an evaporation section and a condensation section; the condensation section is arc-shaped and is fitted against the periphery of the heat collection pipe, and the condensation section heats the heat collection pipe; the evaporation section is located below the condensation section.

[0008] By adopting the above technical solution, a phase change medium (such as acetone or other refrigerant) is filled into a flat micro heat pipe during use. The phase change medium is liquid at room temperature and accumulates at the bottom of the evaporation section due to gravity. After the heat collection box is irradiated by solar energy, the heated phase change medium evaporates into a gas in the evaporation section and rises to the condensation section. In the condensation section, it contacts the low-temperature heat collection pipe for heat exchange. After heat exchange, it condenses into a liquid and flows back to the evaporation section along the wall of the flat micro heat pipe, thus achieving thermal circulation. When the phase change medium is in laminar or weakly turbulent flow, the phase change medium inside the heat collection pipe is heated unevenly, resulting in a large local temperature gradient and unstable outlet temperature. Designing the condensation section as an arc shape and wrapping it around the heat collection pipe ensures uniform heating of the phase change medium inside the heat collection pipe, making the outlet temperature more stable.

[0009] Optionally, the central angle of each condensation section is 180 degrees; and the projections of adjacent condensation sections onto the vertical plane of the collector tube axis are symmetrically distributed.

[0010] By adopting the above technical solution, the central angle of the condensing section is set to 180 degrees, which increases the contact area between the condensing section and the heat collection tube, thereby improving heat transfer efficiency and ensuring that the liquid in the heat collection tube can be heated uniformly. The symmetrical distribution of the projections of adjacent condensing sections on the vertical plane of the heat collection tube axis further improves the distribution of heat energy, avoids the problem of local overheating or uneven heating, and improves the overall energy conversion efficiency of the heat collector.

[0011] Optionally, an insulation layer is fixedly installed inside the heat collection box, with the bottom of the insulation layer fixedly installed at the bottom of the heat collection box, and the upper end of the insulation layer wrapping the flat micro heat pipe.

[0012] By adopting the above technical solution, the bottom of the insulation layer is fixed to the bottom of the heat collection box, forming a stable structural support. This ensures that the insulation layer will not shift or fall off during long-term use, thus maintaining a good insulation effect. The upper part of the insulation layer partially wraps the flat micro heat pipe, further reducing heat conduction loss to the external environment, improving heat utilization, and enabling the heat collector to achieve higher heat output with lower energy loss.

[0013] Optionally, each of the flat micro heat pipes has multiple microchannels arranged in parallel.

[0014] By adopting the above technical solution, each flat micro heat pipe has multiple microchannels arranged in parallel, which allows heat to be transferred more evenly to the liquid inside the heat collection pipe, thereby improving the overall heat exchange efficiency. At the same time, by setting multiple mutually isolated microchannels, the flow path of the phase change medium can be dispersed, reducing mutual interference between channels in the evaporation section. This structure optimizes the liquid reflux distribution, ensuring smoother liquid flow and thus promoting efficient heat transfer within the flat micro heat pipe.

[0015] Optionally, each of the microchannels is a capillary micropore with a diameter of 2mm-20mm.

[0016] By adopting the above technical solution, the capillary microchannel configuration significantly enhances the capillary liquid absorption capacity inside the flat plate micro heat pipe, making the circulation of the phase change medium between the evaporation and condensation sections smoother. The capillary microchannel configuration, ranging from 2-20 mm, ensures both channel flow and effectively increases the contact area of ​​the medium, thereby improving heat transfer efficiency.

[0017] Optionally, the flow velocity of the liquid inside the heat collection tube is 0.05 m / s to 0.1 m / s.

[0018] By adopting the above technical solution, the liquid inside the heat collector tube flows at a speed of 0.05 m / s to 0.1 m / s, which changes the flow state of the phase change medium and avoids the problems of insufficient heat exchange caused by excessively low flow rates and energy loss caused by excessively high flow rates. This ensures that the phase change medium forms a stable turbulent state inside the heat collector tube, thereby improving heat transfer efficiency.

[0019] In summary, the embodiments of the present invention provide a solar collector based on a flat-plate micro heat pipe, which includes at least one of the following beneficial technical effects:

[0020] 1. During use, the phase change medium is filled into the flat micro heat pipe. At room temperature, the phase change medium is a liquid and accumulates at the bottom of the evaporation section due to gravity. After the heat collection box is irradiated by solar energy, the heated phase change medium evaporates into a gas in the evaporation section and rises to the condensation section. In the condensation section, it contacts the low-temperature heat collection pipe for heat exchange. After heat exchange, it condenses into a liquid and flows back to the evaporation section along the wall of the flat micro heat pipe, achieving heat circulation. In traditional straight heat collection pipes, the phase change medium mainly exists in a laminar or weakly turbulent state. After being heated, the phase change medium forms a thermal gradient along the radial direction of the pipe. The temperature is higher near the pipe wall, while the temperature in the center of the pipe is relatively lower, resulting in low heat exchange efficiency and a large local temperature gradient. By designing the condensation section as an arc shape and wrapping it around the heat collection pipe from both sides, the heating uniformity of the phase change medium can be effectively improved, thereby significantly improving the heat exchange efficiency of the heat collection pipe.

[0021] 2. The condensation section design allows for a closer contact between the flat-plate micro heat pipe and the collector tube, effectively increasing the contact area and significantly improving heat transfer efficiency. Furthermore, it ensures that heat is evenly transferred from the flat-plate micro heat pipe to the collector tube, reducing heat loss and further enhancing the overall heat exchange performance of the solar collector.

[0022] 3. The liquid inside the collector tube flows at a velocity of 0.05 m / s to 0.1 m / s, which changes the flow state of the phase change medium and avoids insufficient heat exchange caused by excessively low flow rates and energy loss caused by excessively high flow rates. This ensures that the phase change medium forms a stable turbulent state inside the collector tube, thereby improving heat transfer efficiency. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 A schematic diagram of a solar collector based on a flat micro heat pipe provided for an embodiment of the present invention;

[0025] Figure 2 An exploded view of a solar collector based on a flat micro heat pipe, provided as an embodiment of the present invention;

[0026] Figure 3 This is a schematic diagram of the structure of a flat plate micro heat pipe in a solar collector based on a flat plate micro heat pipe, provided in an embodiment of the present invention.

[0027] Figure 4 This is a schematic diagram of the microchannel structure in a solar collector based on a flat micro heat pipe, provided as an embodiment of the present invention.

[0028] Explanation of the markings in the image:

[0029] 11. Heat collection box; 12. Heat collection tube; 13. Flat micro heat pipe; 14. Condensation section; 15. Evaporation section; 16. Insulation layer; 17. Microchannel; 18. Absorption coating; 19. Glass cover. Detailed Implementation

[0030] The following is in conjunction with the appendix Figure 1 -4 provides further details regarding this application.

[0031] Combination Figure 1 , Figure 2 and Figure 3This application discloses a solar collector based on a flat micro heat pipe 12, including a heat collection box 1, a heat collection pipe 11, and a flat micro heat pipe 12. The heat collection box 1 is inclined and set on the ground. The heat collection pipe 11 is set inside the heat collection box 1, with both ends of the heat collection pipe 11 set on both sides of the heat collection box 1. One end of the heat collection pipe 11 is a water inlet, and the other end of the heat collection pipe 11 is a water outlet. The flat micro heat pipe 12 is fixedly set around the heat collection pipe 11. Among them, multiple flat micro heat pipes 12 are arranged at intervals along the axis of the heat collection pipe 11. Each flat micro heat pipe 12 includes an evaporation section 122 and a condensation section 121. The condensation section 121 is arc-shaped and is attached to the circumference of the heat collection pipe 11. The condensation section 121 heats the heat collection pipe 11. The evaporation section 122 is located at the lower end of the condensation section 121.

[0032] In this embodiment, the heat collection box 1 is square in shape. The square shape provides a larger surface area, allowing for the installation of more flat micro heat pipes 12, thus increasing the heat density per unit area. Simultaneously, the square structure facilitates the arrangement of the insulation layer 14, and side heat loss can be controlled to within 1%. Therefore, the square shape of the heat collection box 1 better improves the heat collection efficiency of the collector.

[0033] Combination Figure 3 and Figure 4 Each flat micro heat pipe 12 has a condensing section 121 at one end fixed to the heat collector pipe 11, which is attached to the periphery of the heat collector pipe 11. Each flat micro heat pipe 12 has multiple microchannels 15 arranged side-by-side. The flat micro heat pipe 12 is made of metal material formed by welding, stamping, or extrusion. The curvature of the condensing section 121 is simply to fit the heat collector pipe 11. It should be noted that the central angle of each condensing section 121 is 180 degrees; and the projections of adjacent condensing sections 121 onto the vertical plane of the heat collector pipe 11 axis are symmetrically distributed. That is, multiple flat micro heat pipes 12 are arranged alternately, one above the other, on the periphery of the heat collector pipe 11. One flat micro heat pipe 12 is attached to one side of the heat collector pipe 11, and another flat micro heat pipe 12 is positioned opposite to one of the flat micro heat pipes 12. Simultaneously, the axes of the two flat micro heat pipes 12 are collinear. Multiple flat micro heat pipes are arranged sequentially on the heat collector pipe 11 in this manner. The flat micro heat pipe 12 is made of aluminum alloy, which has good ductility and thermal conductivity. The evaporation section 122 is located below the condensation section 121 and is arranged in a straight plate shape. The evaporation section 122 and the condensation section 121 are connected and integrally formed; that is, the condensation section 121 is formed by bending the upper end of the flat micro heat pipe 12.

[0034] It should be noted that each flat micro heat pipe 12 is equipped with multiple microchannels 15. Each microchannel 15 is a capillary micropore with a diameter of 2mm-20mm. The specific surface area can reach 5000-50000 m² / m³ (compared to approximately 100 m² / m³ in conventional equipment), greatly increasing the heat exchange area. The microchannels 15 increase the contact area between the phase change medium and the pipe wall during flow, thereby improving heat exchange efficiency. By setting multiple mutually isolated microchannels 15, the flow path of the phase change medium can be dispersed, reducing mutual interference between channels in the evaporation section. This structure optimizes the liquid reflux distribution, ensuring smoother liquid flow and promoting efficient heat transfer within the flat micro heat pipe 12. Microfins are provided on the inner wall of the microchannels 15, increasing the surface area of ​​the inner wall, significantly expanding the contact area with the fluid, and effectively accelerating the phase change rate of the fluid, thereby further improving heat collection efficiency. Each microchannel 15 is evacuated and filled with a phase change medium, which is a refrigerant.

[0035] In practical use, cold water enters through the inlet of the heat collector tube 11, then exchanges heat with the flat micro heat pipe 12, increasing its temperature before flowing out from the outlet. Since the flat micro heat pipe 12 contains liquid refrigerant, it absorbs solar energy and evaporates into a gaseous state. Due to its lower density, the gaseous refrigerant rises along the microchannel 15 to the condensation section 121, where it exchanges heat with the cold water in the heat collector tube 11. At this point, the cold water and gaseous refrigerant condense. The condensed liquid flows back to the bottom of the flat micro heat pipe 12 under gravity, where it absorbs solar energy again and vaporizes. This process is repeated to heat the cold water in the heat collector tube 11, allowing for continuous heat transfer through the flat micro heat pipe 12. Finally, the heated water is delivered to the user through the heat collector tube 11, thereby improving the solar collector's efficiency.

[0036] Looking back Figure 2 An insulation layer 14 is fixedly installed inside the heat collection box 1. The bottom of the insulation layer 14 is fixedly installed at the bottom of the heat collection box 1, and the upper end of the insulation layer 14 wraps around the flat micro heat pipe 12. An absorption coating 16 is provided on the upper surface of the flat micro heat pipe 12.

[0037] In this embodiment, the insulation layer 14 is made of glass wool with low thermal conductivity, excellent heat insulation properties, non-combustibility, heat resistance, freeze resistance, and corrosion resistance. This design effectively reduces heat loss and improves the overall efficiency of the collector. Furthermore, a glass cover 17 is provided at the upper end of the collector housing 1, forming a closed structure with the collector housing 1 and the glass cover 17 sealed together by a sealing ring. This effectively prevents outside air from entering, maintains an internal vacuum environment, and further enhances the insulation effect.

[0038] Specifically, the upper surface of the flat micro heat pipe 12 is provided with an absorption coating 16. This coating is a heat-absorbing blue film with high solar energy absorption and low thermal emissivity, with a thickness of approximately 5μm-10μm. The heat-absorbing blue film can be prepared by chemical vapor deposition or magnetron sputtering, depending on the process conditions. A glass cover plate 17 is placed on top of the absorption coating 16. The glass cover plate 17 is made of 3mm thick ultra-white tempered glass with an anti-reflective coating to ensure high light transmittance. The glass cover plate 17 is sealed to the heat collection box 1 by a sealing ring, effectively preventing outside air from entering, maintaining an internal vacuum environment, and further improving the heat preservation effect.

[0039] In a specific embodiment of the application, the flow velocity of the liquid inside the heat collection tube 11 is 0.05m / s-0.1m / s.

[0040] The implementation principle of this embodiment is as follows: When sunlight shines on the glass cover plate 17, the light passes through the glass cover plate 17 and reaches the absorption coating 16. The absorption coating 16 converts solar radiation into heat energy. The phase change medium inside the flat micro heat pipe 12 evaporates upon heating, and the heat is quickly transferred to the heat collector pipe 11 through the microchannel 15. The water flow inside the heat collector pipe 11 flows in a turbulent state under the action of the pump, carrying away the heat and transferring it to the user. This significantly improves the heat exchange efficiency of the solar collector and achieves efficient and stable heat transfer.

[0041] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A solar collector based on a flat-plate micro heat pipe, characterized in that, include: The heat collection box (1) is inclined and set on the ground; A heat collection tube (11) is installed inside the heat collection box (1). Both ends of the heat collection tube (11) are located on both sides of the heat collection box (1). One end of the heat collection tube (11) is a water inlet, and the other end of the heat collection tube (11) is a water outlet. A flat micro heat pipe (12) is provided with multiple flat micro heat pipes (12) spaced apart along the axis of the heat collection pipe (11). The flat micro heat pipe (12) includes an evaporation section (122) and a condensation section (121). The condensing section (121) is arc-shaped and is fitted to the periphery of the heat collecting tube (11). The condensing section (121) heats the heat collecting tube (11). The evaporation section (122) is located at the lower end of the condensation section (121); The central angle of each of the condensing sections (121) is 180 degrees; and the projections of adjacent condensing sections (121) on the vertical plane of the axis of the heat collection tube (11) are symmetrically distributed.

2. A solar collector based on a flat-plate micro heat pipe according to claim 1, characterized in that: A heat insulation layer (14) is fixedly installed inside the heat collection box (1). The bottom of the heat insulation layer (14) is fixedly installed at the bottom of the heat collection box (1). The upper end of the heat insulation layer (14) wraps the flat micro heat pipe (12).

3. A solar collector based on a flat-plate micro heat pipe according to claim 1, characterized in that, Each of the flat micro heat pipes (12) has multiple microchannels (15) arranged in parallel.

4. A solar collector based on a flat-plate micro heat pipe according to claim 3, characterized in that, Each of the microchannels (15) is a capillary micropore with a diameter of 2mm-20mm.

5. A solar collector based on a flat-plate micro heat pipe according to claim 1, characterized in that, The flow velocity of the liquid inside the heat collection tube (11) is 0.05m / s-0.1m / s.

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