Solar collector provided with a slow flow section

Abstract

The application provides a solar heat collector with a slow flow part, which comprises a heat collecting pipe and a heat storage water tank, a heat releasing pipe is arranged in the heat releasing part, a slow flow part is arranged on the heat releasing pipe, the slow flow part comprises an expanding part, a uniform diameter part and a reducing part which are connected in sequence, the pipe diameter of the expanding part gradually expands, one end of the pipe diameter is connected to one end of the uniform diameter part, the other end of the pipe diameter is connected to the heat releasing pipe, the pipe diameter of the uniform diameter part remains unchanged, the pipe diameter of the reducing part gradually reduces, one end of the pipe diameter is connected to the other end of the uniform diameter part, and the other end of the pipe diameter is connected to the heat releasing pipe. The application provides the solar heat collector with the slow flow part, so that the flow path area of the heat releasing pipe changes, the fluid is slowed down and impacted in the pipe, and the reducing part is reduced, so that the technical effect of strengthening heat transfer is achieved.

Description

Technical Field

[0001] This invention relates to a solar collector, and more particularly to a solar collector with a slow-flow section. Background Technology

[0002] With the rapid development of modern society and economy, human demand for energy is increasing. However, the reserves of traditional energy sources such as coal, oil, and natural gas are constantly decreasing and becoming increasingly scarce, leading to continuous price increases. At the same time, the environmental pollution caused by conventional fossil fuels is becoming increasingly serious, all of which greatly restrict social development and the improvement of human quality of life. Energy issues have become one of the most prominent problems in the contemporary world. Therefore, the search for new energy sources, especially pollution-free clean energy, has become a hot research topic.

[0003] Solar energy is a clean, inexhaustible energy source with enormous reserves; the total amount of solar radiation received by the Earth's surface each year is 1 × 10⁻⁶. 18 The solar energy density is kW·h, which is more than ten thousand times the world's total annual energy consumption. However, due to the low energy density of solar radiation reaching the Earth (approximately one kilowatt per square meter) and its discontinuous nature, large-scale development and utilization face certain difficulties. Therefore, in order to widely utilize solar energy, not only are technical problems to be solved, but it must also be economically competitive with conventional energy sources.

[0004] Loop heat pipes are a novel type of heat pipe technology. Existing technologies also combine loop heat pipes with solar energy; for example, CN101922814A discloses a loop heat pipe for solar water heaters, including an evaporation section, a condensation section, and an adiabatic section. The adiabatic section is located between the evaporation and condensation sections. The heat pipe shell in the evaporation section contains a working fluid. The evaporation section is a loop pipe formed by connecting two pipe sections via a bend. The two pipe sections at the beginning of the evaporation section have a narrower structure compared to the middle and rear sections. Near the adiabatic section, the two pipe sections at the beginning of the evaporation section merge into the adiabatic section through a vapor working fluid outlet and a liquid working fluid inlet. The pipe connecting the vapor working fluid outlet to the liquid working fluid inlet is positioned higher, while the pipe connecting the liquid working fluid inlet is positioned lower. The pipe after the liquid working fluid inlet in the evaporation section has a downward sloping structure. This invention enhances the evaporation and condensation process of the working fluid inside the heat pipe, increasing the transmission power of the heat pipe at small angles and in horizontal conditions, and also solving the problem of the limited installation options for solar water heaters. 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 heat pipe solar collector. The heat collection chamber of the plate heat pipe solar collector is used as the evaporation chamber. The evaporation chamber is connected to the plate heat pipe in the collector. The evaporation chamber, evaporation channel, condensation chamber, and condensation channel form an independent loop heat pipe, which can automatically transfer the solar heat absorbed by the solar collector to the hot water storage tank connected to the condensation chamber, thereby forming a natural circulation system for solar hot water and efficiently transferring heat.

[0005] However, the above combination of solar energy and a loop heat pipe to achieve evaporation and condensation suffers from low heat exchange efficiency, especially in the heat dissipation pipe section, which requires improvement. Summary of the Invention

[0006] In order to overcome the defects and shortcomings of the existing technology, the present invention provides a novel solar collector structure that can achieve full heat release and heat exchange in the heat release section, thereby improving the heat release effect.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows:

[0008] A solar collector with a flow-retarding section includes a heat collection tube and a hot water storage tank. The heat collection tube is a loop heat pipe, including a heat absorption section and a heat release section. The fluid absorbs solar heat in the heat absorption section and circulates to the heat release section. The heat release section is located in the hot water storage tank. After the fluid releases heat in the heat release section, it circulates back to the heat absorption section. The heat release section includes multiple heat release tubes, and a flow-retarding section is provided between adjacent heat release tubes. The flow-retarding section includes an expanding section, a uniform diameter section, and a contracting section connected in sequence. The diameter of the expanding section gradually increases from one heat release tube to the uniform diameter section. The end with the larger diameter tube is connected to one end of the uniform diameter section, and the end with the smaller diameter tube is connected to the heat release tube. The diameter of the uniform diameter section remains unchanged. The diameter of the contracting section gradually decreases from the uniform diameter section to another heat release tube. The end with the larger diameter tube is connected to the other end of the uniform diameter section, and the end with the smaller diameter tube is connected to the other heat release tube.

[0009] As an improvement, along the flow direction of the fluid inside the heat-dissipating tube, the fluid passes through the expansion section, the equalization section, and the contraction section in sequence. The diameter of the expansion section increases at an increasingly faster rate along the flow direction of the fluid, while the diameter of the contraction section decreases at an increasingly slower rate along the flow direction of the fluid.

[0010] As an improvement, the enlarged section is an arc that bends toward the centerline of the heat dissipation tube, while the reduced section is an arc that bends away from the centerline of the heat dissipation tube.

[0011] As an improvement, the diameter of the uniform diameter section is 1.2-1.6 times that of the heat dissipation pipe.

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

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

[0014] As an improvement, multiple flow-retarding sections are provided on the heat-exchange tube. Along the flow direction of the fluid inside the heat-exchange tube, the length of the expanding section of different flow-retarding sections becomes shorter and the length of the contracting section becomes longer.

[0015] As an improvement, along the flow direction of the fluid inside the heat-releasing tube, the length of the expanding section of the different slow-flow section becomes shorter and shorter, and the length of the contracting section becomes longer and longer.

[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, with adjacent heat exchange tubes connected by upper and lower U-shaped tubes. The leftmost and rightmost heat exchange tubes are connected by a connecting tube, forming a series loop structure between the horizontal tubes, U-shaped tubes, and connecting tubes.

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

[0019] This invention incorporates a flow-retarding section within the heat-exchange tube, with the diameter of the section gradually increasing and decreasing. This flow-retarding section appropriately reduces the fluid velocity within the tube, prolonging the heat exchange process and improving heat transfer efficiency. Furthermore, the increased outer diameter increases the heat exchange area, disrupting the temperature gradient of the fluid inside the tube and acting similarly to fins to enhance heat transfer.

[0020] The diameter of the flow-retarding section of this invention sequentially increases, remains constant, and then decreases. This is because the fluid in the heat-exchange section is a two-phase flow of vapor and liquid. The large-diameter pipe allows for rapid expansion of the vapor through the expansion section, thereby achieving rapid and large-area vapor heat exchange. Furthermore, because the vapor expansion is rapid at the converging section, the vapor and liquid are thoroughly mixed in the converging section, creating vapor-liquid turbulence and further promoting rapid heat exchange. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of the solar collector of the present invention;

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

[0023] Figure 3 This is a schematic diagram of the flow-retarding section structure of the present invention;

[0024] Figure 4 This is another schematic diagram of the flow-retarding section structure of the present invention;

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

[0026] Figure 6 This is a schematic diagram of the hot water storage tank structure of the pulsating heat pipe collector of the present invention. Detailed Implementation

[0027] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0028] Figure 1-6 The solar collector of the present invention is shown. For example... Figure 1 As shown, the solar collector includes a hot water storage tank 1 and a heat collection pipe 2. The heat collection component 2 is a loop heat pipe, including a heat absorption section 21 and a heat release section 22. The heat absorption section 21 absorbs solar energy, and the heat release section is located in the hot water storage tank 1, transferring heat to the water in the tank 1 through the heat release section 22. When the heat absorption section 21 absorbs solar energy, the internal fluid changes from liquid to vapor, then flows into the heat release section. After releasing heat in the heat release section, the internal fluid changes from vapor to liquid, and then circulates back to the heat absorption section for heat absorption.

[0029] As an improvement, such as Figure 2As shown, the heat-dissipating section includes multiple (at least two) heat-dissipating pipes 3, and a flow-retarding section 4 is provided between adjacent heat-dissipating pipes. The flow-retarding section 4 includes an expanding section 41, a uniform diameter section 42, and a contracting section 43 connected in sequence. The diameter of the expanding section gradually increases from one heat-dissipating pipe 3 to the uniform diameter section 42. The end with the larger diameter is connected to one end of the uniform diameter section, and the end with the smaller diameter is connected to the heat-dissipating pipe. The diameter of the uniform diameter section 42 remains unchanged. The diameter of the contracting section gradually decreases from the uniform diameter section to another heat-dissipating pipe, wherein the end with the larger diameter is connected to the other end of the uniform diameter section, and the end with the smaller diameter is connected to another heat-dissipating pipe.

[0030] This invention incorporates a flow-retarding section within the heat-exchange tube, with the diameter of the section gradually increasing and decreasing. This flow-retarding section appropriately reduces the fluid velocity within the tube, prolonging the heat exchange process and improving heat transfer efficiency. Furthermore, the increased outer diameter increases the heat exchange area, disrupting the temperature gradient of the fluid inside the tube and acting similarly to fins to enhance heat transfer.

[0031] The diameter of the flow-retarding section of this invention sequentially increases, remains constant, and then decreases. This is because the fluid in the heat-exchange section is a two-phase flow of vapor and liquid. The large-diameter pipe allows for rapid expansion of the vapor through the expansion section, thereby achieving rapid and large-area vapor heat exchange. Furthermore, because the vapor expansion is rapid at the converging section, the vapor and liquid are thoroughly mixed in the converging section, creating vapor-liquid turbulence and further promoting rapid heat exchange.

[0032] By setting the uniform diameter section 42, this application allows the gas-liquid two-phase flow to pass through a buffer section after rapid expansion, reducing the noise impact caused by rapid expansion and contraction. At the same time, the increased area of ​​the uniform diameter section allows for a longer flow slack time, thereby improving heat exchange efficiency.

[0033] Figure 2 The heat-dissipating tubes in the part are multiple and arranged in parallel. Of course, the heat-absorbing part can also be equipped with multiple heat-absorbing tubes, and the heat-absorbing tubes can also be arranged in parallel.

[0034] As an improvement, along the flow direction of the fluid inside the heat exchange tube, the fluid sequentially passes through an expansion section, a equalization section, and a contraction section. The diameter of the expansion section increases at an increasingly faster rate along the flow direction, while the diameter of the contraction section decreases at a progressively slower rate. Research has also found that the increasingly larger diameter increase in the expansion section allows the internal fluid to expand rapidly and diffuse quickly into the overall slow-flow section, then impact the tube wall for a prolonged period in the contraction section, improving heat exchange efficiency. Furthermore, the reduced diameter in the contraction section further mitigates the noise caused by the impact of the vapor-liquid two-phase flow on the tube.

[0035] As an improvement, such as Figure 4As shown, the enlarged section is an arc bending towards the centerline of the heat exchange tube, while the narrowed section is an arc bending away from the centerline of the heat exchange tube. By setting such curved arcs, the diameter of the enlarged section increases more rapidly along the fluid flow direction, while the diameter of the narrowed section decreases more slowly along the fluid flow direction. This reduces flow dead zones and further improves heat exchange efficiency. Simultaneously, it reduces the impact on the heat exchange tube and also achieves the technical effect of reducing noise.

[0036] As an improvement, the diameter of the uniform diameter section is 1.2-1.6 times that of the heat exchange tube. 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 expanding section is 0.7-0.9 times the length of the contracting section. The above-mentioned size optimization design is based on the optimal dimensional relationships obtained from numerical simulation and experiments, enabling the heat exchange to achieve the best technical effect.

[0037] As an improvement, multiple flow-retarding sections are incorporated into the heat-exchange section. Along the flow direction of the fluid within the heat-exchange section, the length of the expanding sections in different flow-retarding sections gradually decreases, while the length of the contracting sections gradually increases. Because the fluid in the heat-exchange section is a two-phase flow (vapor-liquid), as the fluid continues to flow, the vapor phase decreases while the liquid phase increases, leading to a decrease in heat exchange efficiency. Therefore, by gradually shortening the expanding sections and gradually lengthening the contracting sections, the heat exchange time of the contracting sections is extended, improving heat exchange efficiency. This ensures that the heat exchange per unit length is uniform across the entire heat-exchange tube, avoiding excessively large or small local temperature differences, thereby improving overall heat exchange efficiency. Simultaneously, the presence of vapor phase can cause expansion and noise as the area increases. Since the vapor phase decreases, the length of the expanding sections increases at the front and decreases at the back, resulting in less vapor phase expanding as it enters the expanding sections. This reduces the need for excessive expanding sections to buffer the vapor phase, reducing noise and saving materials. This allows for good heat exchange performance and reduced noise at a low cost.

[0038] As an improvement, along the flow direction of the fluid within the heat-exchange section, the length of the expanding sections of different slow-flow sections decreases by an increasing rate, while the length of the contracting sections increases by an increasing rate. These variations in magnitude are the result of extensive experiments and numerical simulations, and can further reduce costs, improve heat exchange efficiency, and reduce noise.

[0039] As an improvement, such as 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 bends 24 and 25. The leftmost and rightmost heat exchange tubes 23 are connected by a connecting pipe 26, forming a series loop structure. The connecting pipe 26 is located above the upper bend 24 and is spaced apart from it. The heat dissipation section 22 includes the upper part of the heat exchange tubes 23, the upper bend 24, and the connecting pipe 26. The water tank 1 is divided into an independent upper tank 12 and a lower tank 13 by a layered partition 11, with an inlet and an outlet for each tank. The inlet and outlet of the upper and lower tanks are arranged so that the water in the upper tank 12 and the lower tank 13 flows counterclockwise. For example, the inlet and outlet of the upper tank are located on the left and right sides of the upper tank, respectively, and the inlet and outlet of the lower tank are located on the right and left sides of the lower tank. Alternatively, the lower box's inlet and outlet can be located on the left and right sides of the lower box, respectively, while the upper box's inlet and outlet can be located on the right and left sides of the upper box.

[0041] The upper part of the heat exchange tube 23, the upper bend 24 and the connecting tube 26 each include multiple heat dissipation tubes, and a slow flow section is provided between the heat dissipation tubes.

[0042] The layered partition acts as a heat conductor, allowing heat exchange between the fluids in the upper and lower chambers. By installing layered heat-conducting partitions, heat exchange between the fluids in the upper and lower chambers can be achieved, resulting in complementary heat transfer. This allows the higher-temperature fluid in one chamber to transfer heat to the lower-temperature fluid, and then the higher-temperature fluid, after cooling down, absorbs heat from the heat pipe, thus maximizing heat exchange.

[0043] As an improvement, the water flow direction in the upper tank is opposite to the flow direction of the fluid in the connecting pipe, and the water flow direction in the lower tank is opposite to the flow direction of the fluid in the bend. This allows the fluid to flow in the opposite direction to the fluid flow path within the heat pipe, thereby maximizing heat exchange. By implementing stratified flow, true countercurrent flow can be achieved.

[0044] As an improvement, the thermal conductivity of the partition plate varies at different locations, gradually decreasing from the center towards the left and right sides. With the cold water in the upper and lower tanks flowing in opposite directions, the inlet and outlet of the tanks are located on the left and right sides respectively. This maximizes the temperature difference between the two, resulting in the best heat exchange effect. By increasing the thermal conductivity at the center, the heat exchange effect is enhanced, achieving a more balanced heat exchange along the overall length, thus achieving optimal heat exchange performance.

[0045] As an improvement, the thermal conductivity decreases at an increasingly greater rate from the center of the partition plate towards the left and right sides. This design further enhances the heat exchange effect, achieving a more balanced overall heat exchange and ultimately resulting in optimal heat exchange performance.

[0046] While the present invention has been disclosed above with reference to preferred embodiments, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A solar collector with a flow-retardant section, comprising a collector tube and a hot water storage tank, wherein the collector tube is a loop heat pipe, comprising a heat-absorbing section and a heat-releasing section, wherein a fluid absorbs solar heat in the heat-absorbing section and circulates to the heat-releasing section, the heat-releasing section being disposed in the hot water storage tank, and the fluid circulates back to the heat-absorbing section after releasing heat in the heat-releasing section; characterized in that... The heat-dissipating section includes multiple heat-dissipating tubes, with a flow-retarding section between adjacent heat-dissipating tubes. The flow-retarding section includes an expanding section, a equalizing section, and a contracting section connected in sequence. The diameter of the expanding section gradually increases from one heat-dissipating tube to the equalizing section, with the larger diameter end connected to one end of the equalizing section and the smaller diameter end connected to the heat-dissipating tube. The diameter of the equalizing section remains constant. The diameter of the contracting section gradually decreases from the equalizing section to another heat-dissipating tube, with the larger diameter end connected to the other end of the equalizing section and the smaller diameter end connected to the other heat-dissipating tube. The heat exchanger consists of a tube; the fluid in the heat exchange section is a two-phase flow of vapor and liquid; multiple slow-flow sections are provided on the heat exchanger tube, and along the flow direction of the fluid inside the heat exchanger tube, the length of the expanding section of different slow-flow sections becomes shorter and the length of the contracting section becomes longer; the loop heat pipe is a pulsating heat pipe; the pulsating heat pipe includes multiple parallel heat exchange tubes, and adjacent heat exchange tubes are connected by upper and lower U-shaped tubes, with the leftmost and rightmost heat exchange tubes connected by a connecting pipe, forming a series loop structure between the horizontal tubes, U-shaped tubes and connecting pipes.

2. The solar collector as described in claim 1, characterized in that, Along the flow direction of the fluid inside the heat-dissipating tube, the fluid passes through the expansion section, the equalization section, and the contraction section in sequence. The diameter of the expansion section increases at an increasingly faster rate along the flow direction of the fluid, while the diameter of the contraction section decreases at an increasingly slower rate along the flow direction of the fluid.

3. The solar collector as described in claim 2, characterized in that, The enlarged section is an arc that bends towards the centerline of the heat-dissipating tube, while the narrowed section is an arc that bends away from the centerline of the heat-dissipating tube.

4. The solar collector as described in claim 1, characterized in that, The diameter of the uniform diameter section is 1.2-1.6 times that of the heat dissipation pipe.

5. The solar collector as described in claim 1, characterized in that, The length of the uniform diameter section is 20-35% of the total length of the slow-flow section.

6. The solar collector as described in claim 1, characterized in that, The length of the enlarged part is 0.7-0.9 times the length of the reduced part.

7. The solar collector as described in claim 1, characterized in that, Along the flow direction of the fluid inside the heat-dissipating tube, the length of the expanding section of the different slow-flow sections decreases by an increasing rate, while the length of the contracting section increases by an increasing rate.

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