Solar heat collector provided with flow slowing part

Abstract

The solar heat collector comprises a heat collecting pipe and a heat storage water tank, a heat releasing part is provided with a heat releasing pipe, the heat releasing pipe is provided with the flow slowing part, the flow slowing part comprises an expanding part, a diameter uniformizing part and a reducing part which are sequentially connected, the pipe diameter of the expanding part is gradually expanded, the end with the large pipe diameter is connected with one end of the diameter uniformizing part, and the end with the large pipe diameter is connected with the other end of the diameter uniformizing part. The small-pipe-diameter end is connected with the heat release pipe, the pipe diameter of the diameter uniformizing part is kept unchanged, the pipe diameter of the reducing part is gradually reduced, the large-pipe-diameter end is connected with the other end of the diameter uniformizing part, and the small-pipe-diameter end is connected with the heat release pipe. According to the solar heat collector provided by the invention, the flow path area of the heat release pipe is changed through the arrangement of the flow slowing part, so that fluid is promoted to slowly flow in the pipe and impact the reducing part, and the technical effect of enhancing heat transfer is achieved.

Description

Technical Field

[0001] The invention relates to a solar heat collector, in particular to a solar heat collector provided with a slow flow portion. Background Art

[0002] With the rapid economic development of modern society, humanity's demand for energy is increasing. However, the reserves of traditional energy sources such as coal, oil, and natural gas are dwindling and becoming increasingly scarce, leading to rising prices. Furthermore, the environmental pollution caused by conventional fossil fuels is becoming increasingly serious, significantly hindering social development and improving the quality of life. Energy issues have become one of the most prominent issues in the contemporary world. Therefore, the search for new energy sources, particularly clean and pollution-free energy, has become a hot topic of research.

[0003] Solar energy is an inexhaustible clean energy source with huge resources. The total amount of solar radiation energy received by the earth’s surface each year is 1×10 18 kW·h, which is more than 10,000 times the world's total annual energy consumption. However, the low energy density of solar radiation reaching the Earth (approximately 1 kilowatt per square meter) and its discontinuous nature present certain difficulties for large-scale development and utilization. Therefore, in order to widely utilize solar energy, not only must technical challenges be addressed, but it must also be economically competitive with conventional energy sources.

[0004] Loop heat pipes are a new type of heat pipe technology. Prior art also incorporates loop heat pipes with solar energy. For example, CN101922814A discloses a loop heat pipe for solar water heaters, comprising an evaporation section, a condensation section, and an adiabatic section. The adiabatic section is located between the evaporation and condensation sections. A working medium is contained within the heat pipe shell of the evaporation section. The evaporation section is a loop pipe formed by connecting two sections of pipes via an elbow. The two sections of pipes in the front section of the evaporation section have a narrower structure than the middle and rear sections of the evaporation section. The two sections of pipes in the front section of the evaporation section converge at the adiabatic section near the adiabatic section through a vapor working medium outlet and a liquid working medium inlet. The two sections of pipes in the evaporation section have the vapor working medium outlet located at the top and the liquid working medium inlet located at the bottom. The pipe after the liquid working medium inlet in the evaporation section has a downwardly inclined structure. The heat pipe of the present invention enhances the evaporation and condensation process of the working medium within the heat pipe, increasing the heat pipe's transmission power at low angles and in a horizontal state, while also addressing the drawback of the solar water heater's single installation. CN103344052A relates to a solar thermal collection system based on natural circulation of heat pipes. The system mainly consists of an evaporation chamber, an evaporation channel, a condensation chamber, a condensation channel and a plate-type heat pipe solar collector. The heat collection chamber of the plate-type heat pipe solar collector is used as an evaporation chamber. The evaporation chamber is connected to the plate-type heat pipe in the collector. The evaporation chamber, the evaporation channel, the condensation chamber and the condensation channel form an independent loop heat pipe, which can automatically transfer the solar heat absorbed by the solar collector to a hot water storage tank connected to the condensation chamber, thereby forming a solar hot water natural circulation system and efficiently transferring heat.

[0005] However, the aforementioned combination of solar energy and loop heat pipes for evaporation and condensation suffers from low heat exchange efficiency, particularly in the heat release pipe section, which needs improvement. Summary of the Invention

[0006] In order to overcome the defects and shortcomings in the prior art, the present invention provides a solar collector with a novel structure, which can achieve sufficient heat release and heat exchange in the heat release part, thereby improving the heat release effect.

[0007] In order to achieve the above object, the technical solution of the present invention is as follows:

[0008] A solar thermal collector provided with a slow flow portion comprises a heat collecting tube and a hot water storage tank, wherein the heat collecting tube is a loop heat tube comprising a heat absorbing portion and a heat releasing portion, wherein the fluid absorbs solar heat in the heat absorbing portion and circulates to the heat releasing portion, wherein the heat releasing portion is provided in the hot water storage tank, and the fluid circulates back to the heat absorbing portion after releasing heat in the heat releasing portion; the heat releasing portion comprises a plurality of sections of heat releasing tubes, and a slow flow portion is provided between adjacent heat releasing tubes, wherein the slow flow portion comprises an expansion portion, a uniform diameter portion and a reduction portion connected in sequence, wherein the diameter of the expansion portion gradually expands from one section of heat releasing tube to the uniform diameter portion, the end with a larger diameter is connected to one end of the uniform diameter portion, the end with a smaller diameter is connected to the heat releasing tube, the diameter of the uniform diameter portion remains unchanged, and the diameter of the reduction portion gradually reduces from the uniform diameter portion to another section of heat releasing tube, wherein the end with a larger diameter is connected to the other end of the uniform diameter portion, and the end with a smaller diameter is connected to another section of heat releasing tube.

[0009] As an improvement, along the flow direction of the fluid in the heat release tube, the fluid passes through the expansion part, the uniform diameter part and the reduction part in sequence, wherein the diameter of the expansion part increases at an increasingly faster rate along the flow direction of the fluid, and the diameter of the reduction part decreases at an increasingly slower rate along the flow direction of the fluid.

[0010] As an improvement, the expanded portion is an arc that bends toward the center line of the heat release tube, and the contracted portion is an arc that bends away from the center line of the heat release tube.

[0011] As an improvement, the diameter of the uniform diameter portion is 1.2-1.6 times the diameter of the heat release tube.

[0012] As an improvement, the length of the uniform diameter portion is 20-35% of the total length of the slow flow portion.

[0013] As an improvement, the length of the expanded portion is 0.7-0.9 times the length of the reduced portion.

[0014] As an improvement, a plurality of slow flow sections are provided on the heat release tube. Along the flow direction of the fluid in the heat release tube, the lengths of the expansion sections of the different slow flow sections become shorter and shorter, and the lengths of the contraction sections become longer and longer.

[0015] As an improvement, along the flow direction of the fluid in the heat release pipe, the lengths of the expansion parts of different slow flow parts are shortened and the lengths of the contraction parts are lengthened.

[0016] As an improvement, the loop heat pipe is a pulsating heat pipe.

[0017] As an improvement, the pulsating heat pipe includes multiple parallel heat exchange tubes, and adjacent heat exchange tubes are connected through upper and lower U-shaped tubes. The leftmost and rightmost heat exchange tubes are connected through connecting tubes, and a series loop structure is formed between the horizontal tubes, U-shaped tubes and connecting tubes.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] The present invention provides a slow-flow portion within the heat release tube, with the diameter of the slow-flow portion sequentially expanding and contracting. This slow-flow portion can appropriately reduce the flow rate of the fluid within, prolonging the heat exchange process and improving heat exchange efficiency. Furthermore, the increased outer diameter increases the heat exchange area, disrupting the temperature bottom layer of the fluid within the tube, acting like a fin and enhancing heat transfer.

[0020] The diameter of the slow-flow section of the present invention sequentially expands, remains constant, and then shrinks. Because the fluid in the heat release section is a vapor-liquid two-phase flow, the large diameter of the expanding section allows for rapid vapor expansion, thereby achieving rapid and large-area vapor heat exchange. Furthermore, because the vapor expansion is rapidly concentrated in the shrinking section, the vapor and liquid are fully mixed in the shrinking section, creating turbulent flow and promoting rapid heat exchange. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic structural diagram of a solar thermal collector of the present invention;

[0022] Figure 2 This is a schematic structural diagram of a loop heat pipe collector provided with a slow flow portion according to the present invention;

[0023] Figure 3 It is a structural schematic diagram of the slow flow portion of the present invention;

[0024] Figure 4 This is another schematic diagram of the slow flow portion structure of the present invention;

[0025] Figure 5 is another schematic diagram of the pulsating heat pipe collector of the present invention;

[0026] Figure 6 It is a schematic structural diagram of the pulsating heat pipe collector water storage tank of the present invention. DETAILED DESCRIPTION

[0027] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0028] Figure 1-6 The solar thermal collector of the present invention is shown. Figure 1 As shown, the solar thermal collector includes a hot water storage tank 1 and a heat collecting pipe 2. The heat collecting component 2 is a loop heat pipe, including a heat absorbing portion 21 and a heat releasing portion 22. The heat absorbing portion 21 absorbs solar heat, and the heat releasing portion is arranged in the hot water storage tank 1 and transfers heat to the water in the water tank 1 through the heat releasing portion 22. The heat absorbing portion 21 absorbs solar energy, and the internal fluid changes from liquid to vapor, which then flows into the heat releasing portion. After the heat is released in the heat releasing portion, the internal fluid changes from vapor to liquid and then circulates back to the heat absorbing portion to absorb heat.

[0029] As an improvement, Figure 2As shown, the heat release portion includes multiple sections (at least two sections) of heat release tubes 3, and a slow flow portion 4 is arranged between adjacent heat release tubes. The slow flow portion 4 includes an expansion portion 41, a uniform diameter portion 42 and a reduction portion 43 connected in sequence. The diameter of the expansion portion gradually increases from one section of the heat release tube 3 to the uniform diameter portion 42, the end with a larger diameter is connected to one end of the uniform diameter portion, and the end with a smaller diameter is connected to the heat release tube. The diameter of the uniform diameter portion 42 remains unchanged, and the diameter of the reduction portion gradually decreases from the uniform diameter portion to the other section of the heat release tube, wherein the end with a larger diameter is connected to the other end of the uniform diameter portion, and the end with a smaller diameter is connected to the other section of the heat release tube.

[0030] The present invention provides a slow-flow portion within the heat release tube, with the diameter of the slow-flow portion sequentially expanding and contracting. This slow-flow portion can appropriately reduce the flow rate of the fluid within, prolonging the heat exchange process and improving heat exchange efficiency. Furthermore, the increased outer diameter increases the heat exchange area, disrupting the temperature bottom layer of the fluid within the tube, acting like a fin and enhancing heat transfer.

[0031] The diameter of the slow-flow section of the present invention sequentially expands, remains constant, and then shrinks. Because the fluid in the heat release section is a vapor-liquid two-phase flow, the large diameter of the expanding section allows for rapid vapor expansion, thereby achieving rapid and large-area vapor heat exchange. Furthermore, because the vapor expansion is rapidly concentrated in the shrinking section, the vapor and liquid are fully mixed in the shrinking section, creating turbulent flow and promoting rapid heat exchange.

[0032] By setting up the uniform diameter portion 42, the present application can make the gas-liquid two-phase flow fluid pass through a buffer section after rapid expansion, thereby reducing the noise impact caused by rapid expansion and contraction. At the same time, it can also improve the heat exchange efficiency by slowing down the flow for a long time at the position where the area of ​​the uniform diameter section is increased.

[0033] Figure 2 The heat emitting tubes are multiple and in parallel structure. Of course, the heat absorbing part can also be provided with multiple heat absorbing tubes, and the heat absorbing tubes can also be provided with a parallel structure.

[0034] As an improvement, along the flow direction of the fluid in the heat release tube, the fluid passes through the expansion part, the uniform diameter part, and the reduction part in sequence. The diameter of the expansion part increases at an increasingly faster rate along the flow direction of the fluid, while the diameter of the reduction part decreases at an increasingly slower rate along the flow direction of the fluid. At the same time, the research found that by increasing the diameter of the expansion part, the internal fluid can expand rapidly, quickly diffuse to the overall slow flow part, and then impact the wall for a long time in the reduction part, thereby improving the heat exchange efficiency. In addition, by setting the reduction part to reduce the amplitude, the noise impact caused by the impact of the gas-liquid two-phase flow on the tube can be further alleviated.

[0035] As an improvement, Figure 4As shown in the figure, the expanded portion curves toward the centerline of the heat release tube, while the reduced portion curves away from the centerline. By creating these curved curves, the diameter of the expanded portion increases more rapidly along the flow direction, while the diameter of the reduced portion decreases more slowly along the flow direction. This reduces dead zones and further enhances heat exchange. This also reduces impact on the heat exchange tube and reduces noise.

[0036] As an improvement, the diameter of the uniform diameter section is 1.2-1.6 times that of the heat release section. As an improvement, the length of the uniform diameter section is 20-35% of the total length of the slow-flow section. As an improvement, the length of the expanded section is 0.7-0.9 times the length of the reduced section. The above-mentioned optimized design is based on the optimal dimensional relationship obtained through numerical simulation and experimentation, which can achieve the best technical effect in heat exchange.

[0037] As an improvement, multiple slow-flow sections are provided on the heat release section. Along the flow direction of the fluid within the heat release section, the length of the expansion section of each slow-flow section becomes increasingly shorter, while the length of the contraction section becomes increasingly longer. Because the fluid in the heat release section is a vapor-liquid two-phase flow, as the fluid continues to flow, the vapor phase decreases and the liquid phase increases, resulting in a progressively poorer heat exchange effect. Therefore, by gradually shortening the expansion section and lengthening the contraction section, the heat exchange time of the contraction section is extended, improving heat exchange efficiency. This ensures that the heat exchange rate per unit length of the entire heat release tube is consistent, avoiding local temperature differences that are excessive or insignificant, thereby improving overall heat exchange efficiency. Furthermore, because the presence of the vapor phase causes the vapor phase to expand and generate noise when the area increases, the length of the expansion section at the front increases, while the length of the expansion section at the back decreases. This reduces the amount of vapor phase expanding upon entering the expansion section, eliminating the need for excessive expansion sections to buffer the vapor phase, reducing noise and thus saving materials. This allows for good heat exchange and noise reduction at a low cost.

[0038] As an improvement, along the flow direction of the fluid within the heat release section, the length of the expansion section of the different slow-flow sections has been gradually shortened, while the length of the contraction section has been gradually lengthened. This variation, the result of extensive experiments and numerical simulations, can further reduce costs, improve heat transfer efficiency, and reduce noise.

[0039] As an improvement, Figure 5 As shown, the loop heat pipe is a pulsating heat pipe.

[0040] The pulsating heat pipe includes multiple parallel heat exchange tubes 23. Adjacent heat exchange tubes are connected by upper and lower elbows 24 and 25. The leftmost and rightmost heat exchange tubes 23 are connected by a connecting pipe 26. The heat exchange tubes 23, elbows 24 and 25, and connecting pipe 26 form a series loop structure. The connecting pipe 26 is located above the upper elbow 24 and is separated from the upper elbow 24. The heat release portion 22 includes the upper portion of the heat exchange tubes 23, the upper elbow 24, and the connecting pipe 26. The water tank 1 is provided with an upper tank 12 and a lower tank 13 that are independent of each other via a layered partition 11. The upper tank 12 and the lower tank 13 each have an inlet and an outlet. The inlet and outlet of the upper tank 12 and the lower tank 13 are arranged so that the water in the upper tank 12 and the lower tank 13 flows in countercurrent to each other. For example, the inlet and outlet of the upper tank are located on the left and right sides of the upper tank, respectively, while the inlet and outlet of the lower tank are located on the right and left sides of the lower tank. Alternatively, the inlet and outlet of the lower box are respectively arranged on the left and right sides of the lower box, and the inlet and outlet of the upper box are respectively arranged on the right and left sides of the upper box.

[0041] The upper portion of the heat exchange tube 23, the upper bent tube 24 and the connecting tube 26 each include multiple sections of heat release tubes, and slow flow portions are provided between the heat release tubes.

[0042] The layered baffles are heat conductors, and the fluids in the upper and lower boxes can exchange heat through the baffles. By setting up layered heat-conducting baffles, heat exchange between the fluids in the upper and lower boxes can be achieved, so that the heat in the upper and lower boxes is complementary. This allows the hotter fluid in the upper and lower boxes to transfer heat to the cooler fluid. The hotter fluid then cools down and absorbs the heat from the heat pipe, thus achieving maximum heat exchange.

[0043] As an improvement, the water in the upper tank flows in the opposite direction to the fluid in the connecting pipe, and the water in the lower tank flows in the opposite direction to the fluid in the elbow. This allows the fluid to flow in opposite directions to the fluid in the heat pipe layer, thereby maximizing heat exchange. By achieving stratified flow, true countercurrent flow can be achieved.

[0044] As an improvement, the thermal conductivity of the partition plate varies at different locations, decreasing gradually from the center to the left and right sides. When the cold water in the upper and lower tanks flows in countercurrent, the inlet and outlet of the tanks are located on the left and right sides, respectively. This maximizes the temperature difference between the two and achieves the best heat exchange. This is because by increasing the thermal conductivity in the middle, the heat exchange effect is increased, resulting in a balanced heat exchange along the entire length, achieving overall heat balance and achieving the best heat exchange effect.

[0045] As an improvement, the thermal conductivity gradually decreases from the middle of the partition plate to the left and right sides. The above setting can further increase the heat exchange effect, so that the overall heat exchange is balanced, achieving overall heat exchange balance, thereby further achieving the best heat exchange effect.

[0046] Although the present invention has been disclosed above with reference to preferred embodiments, the present invention is not limited thereto. Any person skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be subject to the scope defined by the claims.

Claims

1. A solar thermal collector with a slow flow portion, comprising a heat collecting tube and a heat storage tank, wherein the heat collecting tube is a loop heat pipe, comprising a heat absorbing portion and a heat releasing portion, wherein the fluid absorbs solar heat in the heat absorbing portion and circulates to the heat releasing portion, wherein the heat releasing portion is disposed in the heat storage tank, and the fluid circulates back to the heat absorbing portion after releasing heat in the heat releasing portion; characterized in that: The heat release portion includes multiple sections of heat release tubes, and a slow flow portion is arranged between adjacent heat release tubes. The slow flow portion includes an expansion portion, a uniform diameter portion and a reduction portion connected in sequence. The diameter of the expansion portion gradually increases from one section of the heat release tube to the uniform diameter portion, the end with a larger diameter is connected to one end of the uniform diameter portion, and the end with a smaller diameter is connected to the heat release tube. The diameter of the uniform diameter portion remains unchanged, and the diameter of the reduction portion gradually decreases from the uniform diameter portion to another section of the heat release tube, wherein the end with a larger diameter is connected to the other end of the uniform diameter portion, and the end with a smaller diameter is connected to another section of the heat release tube.

2. The solar thermal collector according to claim 1, wherein Along the flow direction of the fluid in the heat release tube, the fluid passes through the expansion part, the uniform diameter part and the reduction part in sequence, wherein the diameter of the expansion part increases faster and faster along the flow direction of the fluid, and the diameter of the reduction part decreases slower and slower along the flow direction of the fluid.

3. The solar thermal collector according to claim 2, wherein: The expanded portion is an arc that bends toward the center line of the heat release tube, and the reduced portion is an arc that bends away from the center line of the heat release tube.

4. The solar thermal collector according to claim 1, wherein The diameter of the uniform diameter portion is 1.2-1.6 times the diameter of the heat release tube.

5. The solar thermal collector according to claim 1, wherein The length of the uniform diameter portion is 20-35% of the total length of the slow flow portion.

6. The solar thermal collector according to claim 1, wherein: The length of the expanded portion is 0.7-0.9 times the length of the reduced portion.

7. The solar thermal collector according to claim 1, wherein A plurality of slow flow parts are arranged on the heat release pipe. Along the flow direction of the fluid in the heat release pipe, the length of the expansion part of the different slow flow parts becomes shorter and the length of the contraction part becomes longer.

8. The solar thermal collector according to claim 7, characterized in that Along the flow direction of the fluid in the heat release pipe, the lengths of the expansion parts of the different slow flow parts are shortened and the lengths of the contraction parts are lengthened and the lengths are lengthened.

9. The solar thermal collector according to claim 7, characterized in that Loop heat pipes are pulsating heat pipes.

10. The solar thermal collector according to claim 7, characterized in that The pulsating heat pipe includes multiple parallel heat exchange tubes. Adjacent heat exchange tubes are connected through upper and lower U-shaped tubes. The leftmost and rightmost heat exchange tubes are connected through a connecting tube. A series loop structure is formed between the horizontal tubes, U-shaped tubes and connecting tubes.

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