Supercritical carbon dioxide flow and wall temperature testing system in parallel horizontal coiled pipe

Abstract

The invention belongs to the technical field of experimental test equipment, and relates to a supercritical carbon dioxide flow and wall temperature test system in a parallel horizontal coiled pipe, which comprises a storage tank, a test box, a first conveying assembly, a cooling assembly, a disc type condensation assembly, a flow detection assembly and a temperature detection assembly. According to the invention, a plurality of coiled pipes in the test box can be heated, and supercritical carbon dioxide in the coiled pipes is heated through the coiled pipes, so that an adjustable heat flux density is provided for simulating the flowing and heat transfer of the supercritical carbon dioxide; meanwhile, the flow of the supercritical carbon dioxide in each coiled pipe, the total flow of the supercritical carbon dioxide in the multiple coiled pipes and the temperatures of multiple positions on each coiled pipe are detected, and the flow distribution rule and the wall temperature distribution rule of the supercritical carbon dioxide are obtained through analysis; therefore, the supercritical carbon dioxide flow and heat transfer rule under the non-uniform heat flow condition is determined, and a theoretical basis is provided for operation of a supercritical carbon dioxide cycle power generation light condensation and heat collection system.

Description

Technical Field

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

[0002] The thermal cycle system is an indispensable stage for realizing the conversion of thermal energy into electrical energy. Compared with the traditional steam Rankine cycle, the Brayton thermal cycle system has a higher cycle efficiency. Among them, the Brayton cycle system with supercritical carbon dioxide as the working medium combines the advantages of the Rankine cycle and the Brayton cycle, has a higher thermal conversion efficiency, and within the temperature range of 400°C - 750°C, its cycle thermal efficiency can reach up to 45% - 50%, which is significantly higher than the steam power cycle efficiency.

[0003] Supercritical carbon dioxide can be used as both the working medium of the power cycle and the heat transfer fluid of the heat absorber in a direct solar thermal power generation system. This system has a simple structure, a high operating temperature, and a high system efficiency, and is one of the research hotspots of solar thermal power generation systems. However, affected by the seasonality and timeliness of solar energy, the heat flux density in the heat absorber that collects solar radiant energy is extremely unevenly distributed in time and space, and the temperature and pressure of the heat transfer medium in the tube increase or decrease accordingly. And a slight change in the temperature and pressure of supercritical carbon dioxide will cause a drastic change in its physical properties, which will lead to phenomena such as a decrease in the heat transfer performance of the working medium and abnormal local wall temperature in the entire heat absorption system. This not only affects the heat exchange ability of the working medium and causes a decrease in the power cycle efficiency, but also makes the local wall temperature exceed the material tolerance limit, posing a hidden danger to the stable and safe operation of the supercritical carbon dioxide cycle power generation concentrating solar heat collection system.

[0004] At present, the research on the flow and heat transfer of supercritical carbon dioxide in pipelines is still limited to the conditions of constant heat flux and constant wall temperature, lacking the 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 unevenly distributed in time and space, laying a hidden danger for the stable and safe operation of the supercritical carbon dioxide cycle power generation concentrating solar heat collection system. Summary of the Invention

[0005] The purpose of the present invention is to provide a supercritical carbon dioxide flow rate and wall temperature testing system 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 flux conditions, and avoid the occurrence of failures in the operation of the supercritical carbon dioxide cycle power generation concentrating solar heat collection system.

[0006] To achieve the above purpose, the specific technical solution provided by the present invention is as follows: A supercritical carbon dioxide flow rate and wall temperature testing system in a parallel horizontal serpentine tube, comprising: A storage tank for storing supercritical carbon dioxide inside.

[0007] A test chamber, with multiple serpentine tubes arranged side by side on the inner wall. The input ends of the multiple serpentine tubes are connected through a flow divider, and the output ends of the multiple serpentine tubes are connected through 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.

[0008] A dish-shaped concentrating assembly, used to concentrate solar rays and enter the heating test chamber to heat the multiple serpentine tubes, thereby heating supercritical carbon dioxide and providing a controllable heat flux density for simulating the flow and heat transfer of supercritical carbon dioxide.

[0009] A flow rate detection assembly, arranged on the multiple serpentine tubes, used to respectively detect the branch flow rate of supercritical carbon dioxide in each serpentine tube and the total flow rate of supercritical carbon dioxide in the multiple serpentine tubes, and determine the flow distribution law in the multiple serpentine tubes through the branch flow rate and total flow rate of supercritical carbon dioxide.

[0010] A temperature detection assembly, arranged on the multiple serpentine tubes, used to respectively detect the temperatures at multiple positions on each serpentine tube, determine the wall temperature distribution law through the temperatures at multiple positions, and combine the flow distribution law to determine the flow and heat transfer law of supercritical carbon dioxide under non-uniform heat flux conditions.

[0011] The features of the present invention also lie in: Among them, the first conveying assembly includes: A first conveying pump, with its input end connected to the outlet of the storage tank and its output end connected to the flow divider.

[0012] Among them, the cooling assembly includes: A cooler, with its first input end connected to the flow combiner and its first output end connected to the inlet of the storage tank.

[0013] A water tank, storing cooling water inside.

[0014] A second conveying pump, with its input end connected to the outlet of the water tank, its output end connected to the second input end of the cooler, and the second output end of the cooler connected to the inlet of the water tank.

[0015] Among them, the dish-shaped concentrating assembly includes: A dish-shaped concentrator, arranged below the test chamber.

[0016] A flat glass. One side of the test chamber close to the dish-shaped concentrator is an open structure, and the flat glass is arranged at the opening of the test chamber, and the focus of the dish-shaped concentrator is directly opposite the flat glass.

[0017] Among them, the flow rate detection assembly includes: Multiple first flow meters, corresponding to the multiple serpentine tubes one by one. Each first flow meter is arranged on the corresponding serpentine tube and is close to the input end of the multiple serpentine tubes.

[0018] A second flowmeter is arranged at the output end of the first delivery pump.

[0019] The temperature detection component includes: Multiple groups of temperature sensors, which correspond to multiple serpentine tubes one by one. The multiple groups of temperature sensors are arranged side by side on the multiple serpentine tubes. Each group of temperature sensors has multiple sensors, and the multiple temperature sensors are arranged along the length direction of the corresponding serpentine tube.

[0020] The test chamber is made of stainless steel, and a heat insulation layer is arranged on the side of the test chamber.

[0021] The parallel horizontal serpentine tube internal supercritical carbon dioxide flow rate and wall temperature test system of the present invention has the following advantages: Through the cooperation of the storage tank, the test chamber, the dish-shaped concentrating component, the flow rate detection component and the temperature detection component, the dish-shaped concentrating component can concentrate solar rays into multiple serpentine tubes in the heating test chamber, and then heat the supercritical carbon dioxide therein through the multiple serpentine tubes, providing a controllable heat flux density for simulating the flow and heat transfer of supercritical carbon dioxide. At the same time, the flow rate of supercritical carbon dioxide in each serpentine tube, the total flow rate of supercritical carbon dioxide in the multiple serpentine tubes and the temperatures at multiple positions on each serpentine tube are detected, and the flow rate distribution law and wall temperature distribution law of supercritical carbon dioxide are analyzed, so as to determine the flow and heat transfer laws of supercritical carbon dioxide under non-uniform heat flux conditions, providing a theoretical basis for the operation of the supercritical carbon dioxide cycle power generation concentrating heat collection system and avoiding faults in the operation of the supercritical carbon dioxide cycle power generation concentrating heat collection system. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0023] Figure 2 It is a schematic diagram of the structure of the dish-shaped concentrating component in the present invention.

[0024] Figure 3 It is a schematic top view structure diagram of the test chamber in the present invention.

[0025] Figure 4 It is a schematic diagram of the structure of multiple serpentine tubes connected in parallel in the present invention.

[0026] Figure 5 It is a schematic left view structure diagram of the test chamber in the present invention.

[0027] Reference numerals: 1. Storage tank, 2. First transfer pump, 3. First flowmeter, 4. Test box, 5. Cooler, 6. Water tank, 7. Second transfer pump, 8. Sunlight, 9. Dish-type concentrator, 10. Support, 11. Flat glass, 12. Thermal insulation layer, 13. Temperature sensor, 14. Coiled pipe, 15. Medium inlet, 16. Medium outlet, 17. Second flowmeter. Detailed implementation manner

[0028] The technical solutions in the present application will be clearly and elaborately described below in conjunction with the accompanying drawings. Among them, in the description of the embodiments of the present application, unless otherwise specified, " / " means "or". For example, A / B may mean A or B. The "and / or" in the text is only a description of the association relationship of the associated objects, indicating that there can be three relationships. For example, A and / or B may mean: A exists alone, A and B exist simultaneously, and B exists alone. In addition, in the description of the embodiments of the present application, "a plurality of" means two or more than two. The following terms "first" and "second" are only used for descriptive purposes and cannot be understood as implying or indicating relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features.

[0029] As Figure 1As shown in the figure, the present invention provides a supercritical carbon dioxide flow rate and wall temperature testing system in a parallel horizontal serpentine tube, which includes a storage tank 1, a testing box 4, a dish-shaped concentrating component, a flow rate detection component and a temperature detection component. The inside of the storage tank 1 is used to store supercritical carbon dioxide. A plurality of serpentine tubes 14 are arranged on the inner wall of the testing box 4. The serpentine tubes 14 are arranged side by side. The input ends of the plurality of serpentine tubes 14 are connected through a shunt component, and the output ends of the plurality of serpentine tubes 14 are connected through a confluence component. The shunt component is connected to the outlet of the storage tank 1 through a first conveying component, and the confluence component is connected to the inlet of the storage tank 1 through a cooling component. The first conveying component is used to convey the supercritical carbon dioxide in the storage tank 1 into the serpentine tubes 14. The cooling component is used to cool the heated supercritical carbon dioxide so that the temperature of the supercritical carbon dioxide is reduced to the storage temperature required by the storage tank 1. The dish-shaped concentrating component is used to concentrate the solar rays 8 into the heating testing box 4 to heat the serpentine tubes 14, thereby heating the supercritical carbon dioxide, providing a controllable heat flux density for simulating the flow and heat transfer of supercritical carbon dioxide. The flow rate detection component is arranged on the plurality of serpentine tubes 14. The flow rate detection component is used to respectively detect the branch flow rate of the supercritical carbon dioxide in each serpentine tube 14 and the total flow rate of the supercritical carbon dioxide in the plurality of serpentine tubes 14. The flow rate distribution law in the plurality of serpentine tubes 14 is determined through the branch flow rate and the total flow rate of the supercritical carbon dioxide. The temperature detection component is arranged on the plurality of serpentine tubes 14. The temperature detection component is used to respectively detect the temperatures at a plurality of different positions on each serpentine tube 14. The wall temperature distribution law is determined through the temperatures at the plurality of positions, and the carbon dioxide flow and heat transfer law is determined in combination with the flow rate distribution law. The solar rays 8 are concentrated by the dish-shaped concentrating component into the plurality of serpentine tubes 14 in the heating testing box 4, and then the supercritical carbon dioxide in the plurality of serpentine tubes 14 is heated, providing a controllable heat flux density for simulating the flow and heat transfer of supercritical carbon dioxide. At the same time, the branch flow rate of the supercritical carbon dioxide in each serpentine tube 14, the total flow rate of the supercritical carbon dioxide in the plurality of serpentine tubes 14 and the temperatures at a plurality of positions on each serpentine tube 14 are detected, and the flow rate distribution law and the wall temperature distribution law of the supercritical carbon dioxide are analyzed, so as to determine the flow and heat transfer law of supercritical carbon dioxide under non-uniform heat flux conditions, providing a theoretical basis for the operation of the supercritical carbon dioxide cycle power generation concentrating solar heat collection system and avoiding faults in the operation of the supercritical carbon dioxide cycle power generation concentrating solar heat collection system.

[0030] Among them, when the dish-shaped concentrating component specifically adjusts the heat flux density, the following method is adopted: When natural sunlight is adopted, the received solar radiant energy changes continuously with time, and the heat flux density projected into the test chamber 4 itself will change. The real-time solar irradiance is measured by an illuminance tester, and the measured solar irradiance data is collected and sorted. Combining with the area of the dish concentrator 9, the solar heat flux density received by the test chamber 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.

[0031] As Figure 1 shown, the first conveying component 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 shunt component. Starting the first conveying pump 2, the first conveying pump 2 conveys the supercritical carbon dioxide in the storage tank 1 into a plurality of serpentine tubes 14.

[0032] As Figure 1 shown, the cooling component includes a cooler 5 and a second conveying pump 7. The first input end of the cooler 5 is connected to the confluence component, 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 conveying pump 7 is connected to the outlet of the water tank 6, the output end of the second conveying pump 7 is connected to the second input end of the cooler 5, and the second output end of the cooler 5 is connected to the inlet of the water tank 6. Starting the second conveying pump 7, the second conveying pump 7 conveys the cooling water into the cooler 5, where it exchanges heat with the supercritical carbon dioxide entering the cooler 5, so that the temperature of the supercritical carbon dioxide is reduced to the storage temperature required by the storage tank 1, and the cooling water with increased temperature re-enters the water tank 6.

[0033] As Figure 1 shown, the number of serpentine tubes 14 is preferably three. The shunt component is a first four-way pipe, and the four ports of the four-way pipe are respectively connected to the input ends of the three serpentine tubes 14 and the output end of the first conveying pump 2. The shunt component is a second four-way pipe, and the four ports of the second four-way pipe are respectively connected to the output ends of the three serpentine tubes 14 and the first input end of the cooler 5.

[0034] As Figure 2 、 Figure 3 shown, the dish concentrating component includes a dish concentrator 9 and a flat glass 11. The dish concentrator 9 is arranged below the test chamber 4, and the dish concentrator 9 is connected to the ground through a bracket 10. One side of the test chamber 4 close to the dish concentrator 9 is an open structure, and the flat glass 11 is arranged at the opening of the test chamber 4. The focus of the dish concentrator 9 is directly opposite the flat glass 11. The dish concentrator 9 focuses the solar rays 8 and then reflects them to the flat glass 11. The solar rays 8 pass through the flat glass 11 and then enter the test chamber 4 to heat a plurality of serpentine tubes 14.

[0035] As Figure 4As shown in the figure, the flow detection component includes a plurality of first flow meters 3 and a second flow meter 17. The plurality of first flow meters 3 correspond to the plurality of serpentine tubes 14 one by one. Each first flow meter 3 is arranged on the corresponding serpentine tube 14 and is close to the input end of the plurality of serpentine tubes 14. The second flow meter 17 is arranged 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 plurality of serpentine tubes 14.

[0036] As Figure 4 shown in the figure, the temperature detection component includes multiple groups of temperature sensors 13, which correspond to the plurality of serpentine tubes 14 one by one. The multiple groups of temperature sensors 13 are arranged side by side on the plurality of serpentine tubes 14. Each group of temperature sensors 13 has a plurality of sensors, and the plurality of temperature sensors 13 are arranged along the length direction of the corresponding serpentine tube 14. The temperatures at multiple positions on the corresponding serpentine tube 14 are detected by the plurality of temperature sensors 13.

[0037] When it is necessary to determine the flow and heat transfer laws of supercritical carbon dioxide, first determine the average flow through the total flow, that is: total flow / number of serpentine tubes 14. Then, combine the uneven coefficient of the supercritical carbon dioxide flow in each serpentine tube 14, that is: branch flow / average flow, with the wall temperature distribution law measured at multiple positions on each serpentine tube 14. If the flow in the pipeline with a high wall temperature is large and the flow in the pipeline with a low wall temperature is small, it indicates that the entire system is safe. Otherwise, heat transfer deterioration will occur, which may cause overheating and ablation of the pipe wall, threatening the safety of the system.

[0038] As Figure 3 shown in the figure, the test box 4 and each serpentine tube 14 are made of stainless steel. A heat insulation layer 12 is provided on the side of the test box 4 to insulate the inside of the test box 4 through the heat insulation layer 12.

[0039] As Figure 4 、 Figure 5 shown in the figure, medium inlets 15 and medium outlets 16 are respectively opened at positions on the test box 4 close to both ends of each serpentine tube 14. Both ends of each serpentine tube 14 respectively pass through the medium inlet 15 and the medium outlet 16. The flow divider and the flow combiner are both located outside the test box 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.

[0040] Working principle: During the experiment, start the first delivery pump 2 and the second delivery pump 7. The first delivery pump 2 transports the supercritical carbon dioxide in the storage tank 1 into the serpentine tube 14. The dish concentrator 9 focuses the solar rays 8 and then reflects them to the flat glass 11. The solar rays 8 pass through the flat glass 11 and enter the test chamber 4, heating the serpentine tube 14. The flow rate of the supercritical carbon dioxide in the corresponding serpentine tube 14 is measured by the first flowmeter 3 on each serpentine tube 14, and the total flow rate entering the multiple serpentine tubes 14 is detected by the second flowmeter 17. Meanwhile, the temperatures at different positions on the corresponding serpentine tube 14 are detected by multiple temperature sensors 13 on each serpentine tube 14. The heated supercritical carbon dioxide enters the cooler 5 through the medium output end. The second delivery pump 7 transports the 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 and then enter the storage tank 1. The cooling water with increased temperature re-enters the water tank 6. Detect the flow rate of the supercritical carbon dioxide and the temperatures at multiple different positions on the serpentine tube 14. When it is necessary to determine the flow and heat transfer laws of the supercritical carbon dioxide, first determine the average flow rate through the total flow rate, that is: total flow rate / number of serpentine tubes, and then determine the non-uniformity coefficient of the flow rate of the supercritical carbon dioxide in each serpentine tube 14, that is: branch flow rate / average flow rate. Combine the wall temperature distribution laws measured at multiple positions on each serpentine tube 14. If the flow rate of the pipeline with a high wall temperature is large and the flow rate of the pipeline with a low wall temperature is small, it indicates that the entire system is safe. Otherwise, heat transfer deterioration may occur, which may cause the wall temperature of the pipe to exceed the temperature and ablate, threatening the safety of the system.

[0041] It can be understood that the present invention is described through some embodiments. Those skilled in the art know that without departing from the spirit and scope of the present invention, various changes or equivalent replacements can be made to these features and embodiments. Additionally, under the teaching 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 present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application belong to the scope protected by the present invention.

Claims

1. A supercritical carbon dioxide flow rate and wall temperature measurement system in a parallel horizontal serpentine tube, characterized in that, Comprising: A storage tank (1) for storing supercritical carbon dioxide inside; A test chamber (4) with a plurality of serpentine tubes (14) arranged side by side on its inner wall. The input ends of the plurality of serpentine tubes (14) are connected by a shunt member, and the output ends of the plurality of serpentine tubes (14) are connected by a confluence member. The shunt member is connected to the outlet of the storage tank (1) through a first conveying assembly, and the confluence member is connected to the inlet of the storage tank (1) through a cooling assembly; A dish-shaped concentrating assembly for concentrating solar rays into the heating test chamber (4) to heat the plurality of serpentine tubes (14), thereby heating supercritical carbon dioxide and providing a controllable heat flux density for simulating the flow and heat transfer of supercritical carbon dioxide; A flow rate detection assembly arranged on the plurality of serpentine tubes (14) for respectively detecting the branch flow rate of supercritical carbon dioxide in each serpentine tube (14) and the total flow rate of supercritical carbon dioxide in the plurality of serpentine tubes (14), and determining the flow distribution law in the plurality of serpentine tubes (14) based on the branch flow rate and the total flow rate of supercritical carbon dioxide; A temperature detection assembly arranged on the plurality of serpentine tubes (14) for respectively detecting the temperatures at multiple positions on each serpentine tube (14), determining the wall temperature distribution law based on the temperatures at multiple positions, and combining the flow distribution law to determine the flow and heat transfer law of supercritical carbon dioxide under non-uniform heat flux conditions.

2. The supercritical carbon dioxide flow rate and wall temperature test system in a parallel horizontal serpentine tube according to claim 1, characterized in that The first conveying assembly includes: A first conveying pump (2) with its input end connected to the outlet of the storage tank (1), and the output end of the first conveying pump (2) is connected to the shunt member.

3. The supercritical carbon dioxide flow rate and wall temperature test system in a parallel horizontal serpentine tube according to claim 2, wherein The cooling assembly includes: A cooler (5) with its first input end connected to the confluence member, and the first output end of the cooler (5) is connected to the inlet of the storage tank (1); A water tank (6) for storing cooling water inside; A second conveying pump (7) with its input end connected to the outlet of the water tank (6), the output end of the second conveying pump (7) is connected to the second input end of the cooler (5), and the second output end of the cooler (5) is connected to the inlet of the water tank (6).

4. The supercritical carbon dioxide flow rate and wall temperature measurement system in a parallel horizontal serpentine tube according to claim 2, characterized in that The dish-shaped concentrating assembly includes: A dish-shaped concentrator (9) arranged below the test chamber (4); A flat glass (11). One side of the test chamber (4) close to the dish-shaped concentrator (9) is an open structure, and the flat glass (11) is arranged at the opening of the test chamber (4), and the focus of the dish-shaped concentrator (9) is directly opposite the flat glass (11).

5. The supercritical carbon dioxide flow rate and wall temperature measurement system in a parallel horizontal serpentine tube according to claim 2, wherein The flow rate detection assembly includes: A plurality of first flow meters (3) corresponding one by one to the plurality of serpentine tubes (14). Each first flow meter (3) is arranged on the corresponding serpentine tube (14) and close to the input end of the plurality of serpentine tubes (14); A second flow meter (17) arranged at the output end of the first conveying pump (2).

6. The supercritical carbon dioxide flow rate and wall temperature measurement system in a parallel horizontal serpentine tube according to claim 1, wherein, The temperature detection assembly includes: Multiple groups of temperature sensors (13) corresponding one by one to the plurality of serpentine tubes (14). The multiple groups of temperature sensors (13) are arranged side by side on the plurality of serpentine tubes (14). Each group of temperature sensors (13) has a plurality of sensors, and the plurality of temperature sensors (13) are arranged along the length direction of the corresponding serpentine tube (14).

7. The supercritical carbon dioxide flow rate and wall temperature test system in a parallel horizontal serpentine tube according to claim 1, wherein The test chamber (4) is made of stainless steel, and a heat insulation layer (12) is provided on the side of the test chamber (4).

Images