Supercritical carbon dioxide flow and wall temperature test system in parallel horizontal serpentine tube

Abstract

The present application belongs to the technical field of experimental test equipment, and relates to a supercritical carbon dioxide flow and wall temperature test system in parallel horizontal serpentine pipes, comprising a storage tank, a test box, a first conveying assembly, a cooling assembly, a disc-shaped condensing assembly, a flow detection assembly and a temperature detection assembly. The present application can heat multiple serpentine pipes in the test box, and then heat the supercritical carbon dioxide in the multiple serpentine pipes through the multiple serpentine pipes, so as to provide a controllable heat flux density for simulating the flow and heat transfer of supercritical carbon dioxide. Meanwhile, the flow of supercritical carbon dioxide in each serpentine pipe, the total flow of supercritical carbon dioxide in the multiple serpentine pipes and the temperature at multiple positions on each serpentine pipe are detected, the flow distribution law and the wall temperature distribution law of supercritical carbon dioxide are analyzed, and thus the flow and heat transfer law of supercritical carbon dioxide under non-uniform heat flow conditions is determined, thereby providing a theoretical basis for the operation of a supercritical carbon dioxide cycle power generation and light condensation and heat collection system.

Description

Parallel horizontal serpentine tube supercritical carbon dioxide flow rate and wall temperature testing system Technical Field

[0001] This invention belongs to the technical field of experimental testing equipment, and relates to a system for testing supercritical carbon dioxide flow rate and wall temperature in a parallel horizontal serpentine tube. Background Technology

[0002] Thermodynamic cycle systems are an indispensable stage in the conversion of thermal energy into electrical energy. Compared with the traditional steam Rankine cycle, the Brayton thermodynamic cycle system has higher cycle efficiency. Among them, the Brayton cycle system using supercritical carbon dioxide as the working fluid combines the advantages of both the Rankine and Brayton cycles, and has a high thermal conversion efficiency. In the temperature range of 400℃-750℃, its cycle thermal efficiency can reach up to 45%-50%, which is significantly higher than that of steam power cycle efficiency.

[0003] Supercritical carbon dioxide can be used simultaneously as the working fluid in the power cycle and the heat transfer fluid in the receiver in direct solar thermal power generation systems. This system boasts a simple structure, high operating temperature, and high efficiency, making it a hot research topic in solar thermal power generation. However, due to the seasonality and time-sensitivity of solar energy, the heat flux density within the receiver collecting solar radiation is extremely unevenly distributed over time and space, causing the temperature and pressure of the heat transfer medium inside the tube to rise or fall accordingly. Even small changes in the temperature and pressure of supercritical carbon dioxide can lead to drastic changes in its physical properties. This can result in a decrease in the heat transfer performance of the working fluid and abnormal local wall temperatures throughout the receiver system. This not only affects the heat exchange capacity of the working fluid and reduces the efficiency of the power cycle, but also causes the local wall temperature to exceed the material's tolerance limit, posing a threat to the stable and safe operation of the supercritical carbon dioxide cycle power generation concentrator.

[0004] Currently, research on the flow and heat transfer of supercritical carbon dioxide in pipelines is limited to constant heat flux and constant wall temperature conditions. There is a lack of research on the flow and heat transfer of supercritical carbon dioxide in pipelines under non-uniform heat flux conditions where the heat flux density is not uniform with time and space. This poses a hidden danger to the stable and safe operation of supercritical carbon dioxide circulating power generation concentrating solar collector systems. Summary of the Invention

[0005] The purpose of this invention is to provide a system for testing the flow rate and wall temperature of supercritical carbon dioxide in a parallel horizontal serpentine tube, which can test and analyze the flow and heat transfer laws of supercritical carbon dioxide under non-uniform heat flow conditions, and avoid malfunctions in the operation of supercritical carbon dioxide circulating power generation concentrating solar collector systems.

[0006] To achieve the above objectives, the specific technical solution provided by the present invention is as follows:

[0007] A parallel horizontal serpentine tube supercritical carbon dioxide flow rate and wall temperature testing system includes:

[0008] Storage tanks, used to store supercritical carbon dioxide.

[0009] The test chamber has multiple serpentine tubes arranged side by side on its inner wall. The input ends of the multiple serpentine tubes are connected by a flow divider, and the output ends of the multiple serpentine tubes are connected by a flow combiner. The flow divider is connected to the outlet of the storage tank through a first conveying assembly, and the flow combiner is connected to the inlet of the storage tank through a cooling assembly.

[0010] The dish-type concentrator is used to concentrate sunlight into the heating test chamber to heat multiple serpentine tubes, thereby heating supercritical carbon dioxide and providing an adjustable heat flux density for simulating the flow and heat transfer of supercritical carbon dioxide.

[0011] The flow detection component is installed on multiple serpentine tubes to detect the branch flow rate of supercritical carbon dioxide in each serpentine tube and the total flow rate of supercritical carbon dioxide in multiple serpentine tubes. The flow distribution pattern in multiple serpentine tubes is determined by the branch flow rate and the total flow rate of supercritical carbon dioxide.

[0012] Temperature detection components are installed on multiple serpentine tubes to detect the temperature at multiple locations on each tube. The wall temperature distribution pattern is determined by the temperature at multiple locations, and the flow distribution pattern is combined with the flow rate distribution pattern to determine the flow and heat transfer pattern of supercritical carbon dioxide under non-uniform heat flow conditions.

[0013] The invention is further characterized by:

[0014] The first conveying component includes:

[0015] The first transfer pump has its input end connected to the outlet of the storage tank, and its output end connected to the diverter.

[0016] The cooling components include:

[0017] The cooler has its first input end connected to the confluence component and its first output end connected to the inlet of the storage tank.

[0018] The water tank contains cooling water.

[0019] The second delivery pump has its inlet connected to the outlet of the water tank, its outlet connected to the second inlet of the cooler, and its second outlet connected to the inlet of the water tank.

[0020] The dish-type concentrator includes:

[0021] A disc-type condenser is located at the bottom of the test chamber.

[0022] The test chamber has an open structure on the side near the disc condenser, with the flat glass panel positioned at the opening. The focal point of the disc condenser is directly opposite the flat glass panel.

[0023] The flow detection component includes:

[0024] Multiple first flow meters correspond one-to-one with multiple serpentine tubes. Each first flow meter is installed on the corresponding serpentine tube and is located close to the input end of the multiple serpentine tubes.

[0025] The second flow meter is installed at the output end of the first delivery pump.

[0026] The temperature detection component includes:

[0027] Multiple temperature sensors are arranged one-to-one with multiple serpentine tubes. The multiple temperature sensors are arranged side by side on multiple serpentine tubes. Each group of temperature sensors has multiple sensors, and the multiple temperature sensors are arranged along the length of the corresponding serpentine tube.

[0028] The test chamber is made of stainless steel and has an insulation layer on the side.

[0029] The parallel horizontal serpentine tube supercritical carbon dioxide flow rate and wall temperature testing system of the present invention has the following advantages:

[0030] By combining a storage tank, a test chamber, a dish-type concentrator, a flow detection component, and a temperature detection component, sunlight can be focused by the dish-type concentrator into multiple serpentine tubes inside the heating test chamber. These serpentine tubes then heat the supercritical carbon dioxide within, providing an adjustable heat flux density for simulating the flow and heat transfer of supercritical carbon dioxide. Simultaneously, the flow rate of supercritical carbon dioxide in each serpentine tube, the total flow rate of supercritical carbon dioxide in multiple serpentine tubes, and the temperature at multiple locations on each serpentine tube are detected. The flow rate distribution and wall temperature distribution of supercritical carbon dioxide are analyzed, thereby determining the flow and heat transfer characteristics of supercritical carbon dioxide under non-uniform heat flow conditions. This provides a theoretical basis for the operation of the supercritical carbon dioxide circulating power generation concentrator system and prevents malfunctions in the supercritical carbon dioxide circulating power generation concentrator system. Attached Figure Description

[0031] Figure 1 is a schematic diagram of the overall structure of the present invention.

[0032] Figure 2 is a schematic diagram of the structure of the dish-type focusing component in this invention.

[0033] Figure 3 is a top view of the test box in this invention.

[0034] Figure 4 is a schematic diagram of the structure of multiple serpentine tubes connected in parallel in this invention.

[0035] Figure 5 is a schematic diagram of the left-side structure of the test box in this invention.

[0036] Figure label:

[0037] 1. Storage tank; 2. First transfer pump; 3. First flow meter; 4. Test chamber; 5. Cooler; 6. Water tank; 7. Second transfer pump; 8. Sunlight; 9. Disc concentrator; 10. Support frame; 11. Flat glass; 12. Insulation layer; 13. Temperature sensor; 14. Serpentine tube; 15. Medium inlet; 16. Medium outlet; 17. Second flow meter. Detailed Implementation

[0038] The technical solutions of this application will now be described clearly and in detail with reference to the accompanying drawings. In the description of the embodiments of this application, unless otherwise stated, " / " indicates "or," for example, A / B can mean A or B. "And / or" in the text is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, and B alone. Furthermore, in the description of the embodiments of this application, "multiple" refers to two or more. The terms "first" and "second" are used for descriptive purposes only and should not be construed as implying or suggesting relative importance or implicitly indicating the number of indicated technical features. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature.

[0039] As shown in Figure 1, this invention provides a parallel horizontal serpentine tube supercritical carbon dioxide flow rate and wall temperature testing system, including a storage tank 1, a test chamber 4, a dish-type focusing assembly, a flow rate detection assembly, and a temperature detection assembly. The storage tank 1 is used to store supercritical carbon dioxide. Multiple serpentine tubes 14 are arranged side-by-side on the inner wall of the test chamber 4. The input ends of the multiple serpentine tubes 14 are connected by a flow divider, and the output ends of the multiple serpentine tubes 14 are connected by a flow combiner. The flow divider is connected to the outlet of the storage tank 1 by a first conveying assembly, and the flow combiner is connected to the inlet of the storage tank 1 by a cooling assembly. The first conveying assembly... The components are used to transport supercritical carbon dioxide from storage tank 1 to the serpentine tube 14. The cooling component is used to cool the heated supercritical carbon dioxide to the required storage temperature of storage tank 1. The dish-type concentrator is used to concentrate sunlight 8 into the heating test chamber 4 to heat the serpentine tube 14, thereby heating the supercritical carbon dioxide and providing an adjustable heat flux density for simulating the flow and heat transfer of supercritical carbon dioxide. The flow detection component is installed on multiple serpentine tubes 14 and is used to detect the branch flow rate of supercritical carbon dioxide in each serpentine tube 14 and the flow rate of multiple branches. The total flow rate of supercritical carbon dioxide within each serpentine tube 14 is determined by comparing the branch flow rate with the total flow rate. Temperature detection components are installed on each serpentine tube 14 to detect the temperature at multiple different locations on each tube. The wall temperature distribution is determined by analyzing the temperatures at these locations, and combined with the flow rate distribution, the carbon dioxide flow and heat transfer patterns are determined. Sunlight 8 is focused by a dish-type concentrator and directed into the heating test chamber 4 through the serpentine tubes 14, thereby heating the supercritical carbon dioxide within them. Carbon is used to provide an adjustable heat flux density for simulating the flow and heat transfer of supercritical carbon dioxide. At the same time, the branch flow rate of supercritical carbon dioxide in each serpentine tube 14, the total flow rate of supercritical carbon dioxide in multiple serpentine tubes 14, and the temperature at multiple locations on each serpentine tube 14 are detected. The flow distribution law and wall temperature distribution law of supercritical carbon dioxide are analyzed, thereby determining the flow and heat transfer law of supercritical carbon dioxide under non-uniform heat flow conditions. This provides a theoretical basis for the operation of supercritical carbon dioxide circulating power generation concentrating solar collector system and avoids the failure of the supercritical carbon dioxide circulating power generation concentrating solar collector system.

[0040] Specifically, the following method is used to adjust the heat flux density of the dish-type concentrator:

[0041] When natural sunlight is used, the received solar radiation energy changes continuously over time, and the heat flux density inside the projection test box 4 will also change. The real-time solar irradiance is measured by a illuminance meter, and the measured solar irradiance data is collected and organized. Combined with the area of ​​the dish concentrator 9, the solar heat flux density received by the test box 4 can be obtained. When a solar simulator is used as the light source, the heat flux density can also be obtained through the power regulator on the simulator.

[0042] As shown in Figure 1, the first conveying assembly includes a first conveying pump 2. The input end of the first conveying pump 2 is connected to the outlet of the storage tank 1, and the output end of the first conveying pump 2 is connected to the diverter. When the first conveying pump 2 is started, the first conveying pump 2 conveys the supercritical carbon dioxide in the storage tank 1 into multiple serpentine tubes 14.

[0043] As shown in Figure 1, the cooling assembly includes a cooler 5 and a second delivery pump 7. The first input end of the cooler 5 is connected to the confluence member, and the first output end of the cooler 5 is connected to the inlet of the storage tank 1. Cooling water is stored inside the water tank 6. The input end of the second delivery pump 7 is connected to the outlet of the water tank 6, and the output end of the second delivery pump 7 is connected to the second input end of the cooler 5. The second output end of the cooler 5 is connected to the inlet of the water tank 6. When the second delivery pump 7 is started, it delivers cooling water into the cooler 5, where it exchanges heat with the supercritical carbon dioxide entering the cooler 5, causing the temperature of the supercritical carbon dioxide to drop to the storage temperature required by the storage tank 1. The cooled water, after its temperature rises, re-enters the water tank 6.

[0044] As shown in Figure 1, the number of serpentine tubes 14 is preferably three. The diverter is a first four-way pipe, and the four ports of the four-way pipe are respectively connected to the input end of the three serpentine tubes 14 and the output end of the first delivery pump 2. The diverter is a second four-way pipe, and the four ports of the second four-way pipe are respectively connected to the output end of the three serpentine tubes 14 and the first input end of the cooler 5.

[0045] As shown in Figures 2 and 3, the dish-type concentrator assembly includes a dish-type concentrator 9 and a flat glass plate 11. The dish-type concentrator 9 is located below the test chamber 4 and is connected to the ground via a bracket 10. The side of the test chamber 4 closest to the dish-type concentrator 9 has an open structure, and the flat glass plate 11 is located at the opening of the test chamber 4. The focal point of the dish-type concentrator 9 is directly opposite the flat glass plate 11. The dish-type concentrator 9 concentrates the sunlight 8 and reflects it to the flat glass plate 11. The sunlight 8 passes through the flat glass plate 11 and enters the test chamber 4, heating multiple serpentine tubes 14.

[0046] As shown in Figure 4, the flow detection component includes multiple first flow meters 3 and second flow meters 17. The multiple first flow meters 3 correspond one-to-one with multiple serpentine tubes 14. Each first flow meter 3 is installed on the corresponding serpentine tube 14 and is located close to the input end of the multiple serpentine tubes 14. The second flow meter 17 is installed at the output end of the first delivery pump 2. Each first flow meter 3 is used to detect the branch flow of supercritical carbon dioxide in the corresponding serpentine tube 14, and the second flow meter 17 is used to detect the total flow of supercritical carbon dioxide in the multiple serpentine tubes 14.

[0047] As shown in Figure 4, the temperature detection component includes multiple sets of temperature sensors 13, which correspond one-to-one with multiple serpentine tubes 14. The multiple sets of temperature sensors 13 are arranged side by side on the multiple serpentine tubes 14. Each set of temperature sensors 13 has multiple sensors. The multiple temperature sensors 13 are arranged along the length direction of the corresponding serpentine tube 14. The temperature at multiple locations on the corresponding serpentine tube 14 is detected by the multiple temperature sensors 13.

[0048] When it is necessary to determine the flow and heat transfer characteristics of supercritical carbon dioxide, the average flow rate is first determined by the total flow rate, i.e., total flow rate / number of serpentine tubes 14. Then, the non-uniformity coefficient of the supercritical carbon dioxide flow rate in each serpentine tube 14 is calculated, i.e., branch flow rate / average flow rate. Combined with the wall temperature distribution at multiple locations measured on each serpentine tube 14, if the flow rate is large in the pipe with high wall temperature and small in the pipe with low wall temperature, it indicates that the entire system is safe. Conversely, heat transfer deterioration will occur, which may cause the pipe wall to overheat and burn, threatening the safety of the system.

[0049] As shown in Figure 3, the test chamber 4 and each serpentine tube 14 are made of stainless steel. The test chamber 4 is provided with a heat insulation layer 12 on the side, which keeps the inside of the test chamber 4 warm.

[0050] As shown in Figures 4 and 5, a medium inlet 15 and a medium outlet 16 are respectively opened on the test chamber 4 near the two ends of each serpentine tube 14. The two ends of each serpentine tube 14 pass through the medium inlet 15 and the medium outlet 16 respectively. The diverting and merging components are located outside the test chamber 4. The medium input end is connected to the output end of the first delivery pump 2, and the medium output end is connected to the first input end of the cooler 5.

[0051] Working principle: During the experiment, the first delivery pump 2 and the second delivery pump 7 are started. The first delivery pump 2 delivers supercritical carbon dioxide from the storage tank 1 into the serpentine tube 14. The disc concentrator 9 focuses the sunlight 8 and reflects it onto the flat glass 11. The sunlight 8 passes through the flat glass 11 and enters the test chamber 4, heating the serpentine tube 14. The flow rate of supercritical carbon dioxide in each serpentine tube 14 is measured by the first flow meter 3, and the total flow rate entering multiple serpentine tubes 14 is detected by the second flow meter 17. At the same time, the temperature at different locations on each serpentine tube 14 is detected by multiple temperature sensors 13. The heated supercritical carbon dioxide enters the cooler 5 through the medium output end. The second delivery pump 7 delivers cooling water into the cooler 5, which then reacts with the cooling water entering the cooler. The supercritical carbon dioxide in the cooler 5 undergoes heat exchange, reducing its temperature to the required storage temperature in the storage tank 1 before entering the tank. The cooled water, now at a higher temperature, re-enters the water tank 6. The flow rate of the supercritical carbon dioxide and the temperature at multiple locations on the serpentine tube 14 are monitored. To determine the flow and heat transfer characteristics of the supercritical carbon dioxide, the average flow rate is first determined by the total flow rate (total flow rate / number of serpentine tubes). Then, the non-uniformity coefficient of the supercritical carbon dioxide flow rate in each serpentine tube 14 is determined (branch flow rate / average flow rate). Combined with the wall temperature distribution at multiple locations on each serpentine tube 14, if the flow rate is high in the pipe with a high wall temperature and low in the pipe with a low wall temperature, the entire system is safe. Conversely, if the flow rate is low in the pipe with a high wall temperature, heat transfer deteriorates, potentially causing overheating and ablation of the pipe wall, threatening system safety.

[0052] It is understood that the present invention has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the invention. Furthermore, under the teachings of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of the present invention.

Claims

1. A parallel horizontal serpentine tube supercritical carbon dioxide flow rate and wall temperature testing system, characterized in that, include: The storage tank (1) is used to store supercritical carbon dioxide. The test chamber (4) has multiple serpentine tubes (14) arranged side by side. The input ends of the multiple serpentine tubes (14) are connected by a flow divider, and the output ends of the multiple serpentine tubes (14) are connected by a flow combiner. The flow divider is connected to the outlet of the storage tank (1) through a first conveying component, and the flow combiner is connected to the inlet of the storage tank (1) through a cooling component. The dish-type concentrator is used to concentrate sunlight into the heating test chamber (4) to heat the multiple serpentine tubes (14), thereby heating the supercritical carbon dioxide and providing an adjustable heat flux density for simulating the flow and heat transfer of supercritical carbon dioxide. The flow detection component is set in the multiple serpentine tubes. On the serpentine tubes (14), the branch flow rate of supercritical carbon dioxide in each serpentine tube (14) and the total flow rate of supercritical carbon dioxide in multiple serpentine tubes (14) are detected respectively. The flow distribution law in multiple serpentine tubes (14) is determined by the branch flow rate and the total flow rate of supercritical carbon dioxide. Temperature detection components are set on multiple serpentine tubes (14) to detect the temperature at multiple locations on each serpentine tube (14). The wall temperature distribution law is determined by the temperature at multiple locations. Combined with the flow distribution law, the flow and heat transfer law of supercritical carbon dioxide under non-uniform heat flow conditions is determined. When it is necessary to determine the flow and heat transfer law of supercritical carbon dioxide, the average flow rate is first determined by the total flow rate, that is, the total flow rate / the number of serpentine tubes. Then, determine the non-uniformity coefficient of supercritical carbon dioxide flow rate in each serpentine tube (14), i.e., branch flow rate / average flow rate. Combined with the wall temperature distribution pattern measured at multiple locations on each serpentine tube (14), if the flow rate of the pipe with high wall temperature is large and the flow rate of the pipe with low wall temperature is small, it indicates that the whole system is safe. Otherwise, heat transfer deterioration will occur, causing the pipe wall temperature to rise and burn, threatening the safety of the system. The first delivery component includes: a first delivery pump (2), the input end of which is connected to the outlet of the storage tank (1), and the output end of the first delivery pump (2) is connected to the flow divider. The flow detection component includes: multiple first flow meters (3), which correspond one-to-one with multiple serpentine tubes (14). Each first flow meter (3) is set in the corresponding The serpentine tube (14) is located on and near the input end of multiple serpentine tubes (14); the second flow meter (17) is located at the output end of the first delivery pump (2); the temperature detection component includes: multiple sets of temperature sensors (13), which correspond one-to-one with multiple serpentine tubes (14), the multiple sets of temperature sensors (13) are arranged side by side on multiple serpentine tubes (14), each set of temperature sensors (13) has multiple sensors, and the multiple temperature sensors (13) are arranged along the length direction of the corresponding serpentine tube (14); the cooling component includes: a cooler (5), the first input end of which is connected to the confluence member, the first output end of which is connected to the inlet of the storage tank (1); and a water tank (6) which stores cooling water inside.The second delivery pump (7) has its input end connected to the outlet of the water tank (6), and its output end connected to the second input end of the cooler (5). The second output end of the cooler (5) is connected to the inlet of the water tank (6). The disc-type focusing assembly includes: a disc-type focusing device (9) located below the test chamber (4); and a flat glass plate (11). The side of the test chamber (4) near the disc-type focusing device (9) is open, and the flat glass plate (11) is located at the opening of the test chamber (4). The focal point of the disc-type focusing device (9) is directly opposite the flat glass plate (11).

2. The parallel horizontal serpentine tube supercritical carbon dioxide flow rate and wall temperature testing system according to claim 1, characterized in that, The test chamber (4) is made of stainless steel and has an insulation layer (12) on its side.

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