Liquid metal and supercritical fluid multifunctional coupling heat exchange experimental system and method

Abstract

The present invention provides a multifunctional coupled heat exchange experimental system and method for liquid metal and supercritical carbon dioxide, including a liquid metal experimental circuit and a supercritical carbon dioxide experimental circuit. The experimental system can conduct coupled heat exchange studies of liquid metal and supercritical carbon dioxide with large temperature differences, large temperature spans, and high variable heat flows under high temperature and high pressure conditions. It can also conduct separate studies on the flow and heat transfer characteristics of liquid metal coolants and supercritical carbon dioxide in pipelines, as well as experimental studies on the corrosion characteristics of liquid metal on pipelines under oxygen-controlled conditions and natural circulation heat exchange characteristics. The liquid metal experimental circuit mainly consists of a melting tank, a preheating section, an expansion tank, a calibration tank, and corresponding pipelines. The supercritical carbon dioxide experimental circuit mainly consists of a liquid storage tank, a preheating and pressurizing system, a plunger pump, a cooling system, a main heat exchanger, and corresponding pipelines. The maximum temperature of the liquid metal experimental circuit can reach 650°C, the supercritical carbon dioxide pressure can reach 24MPa, and the temperature can reach 560°C.

Description

Technical Field

[0001] The present invention belongs to the field of engineering thermophysics and energy utilization technology, and specifically relates to a multifunctional coupled heat exchange experimental system and method for liquid metal and supercritical fluid, which is used to study the flow and heat exchange characteristics of working fluids, the flow and heat exchange characteristics of natural circulation, and the corrosion characteristics of working fluids on pipelines. Background Art

[0002] As one of the preferred fourth-generation reactor types, the lead-cooled fast reactor (LFR) has excellent application prospects in commercial power generation and power plant applications due to its excellent thermal-hydraulic and safety performance. The lead-cooled fast reactor (LFR) uses liquid metals such as liquid lead (Lead) or liquid lead-bismuth alloy (LBE) as the core coolant, and has advantages such as good thermal neutron performance, high chemical stability, and passive safety performance. The supercritical carbon dioxide (sCO2) Brayton cycle is considered the most promising clean and efficient energy power system, with many advantages such as high efficiency, good flexibility, and compact equipment. The deep integration of the lead-cooled fast reactor and the sCO2 Brayton cycle will surely lead to revolutionary developments in the energy and power sector. As a key device connecting the primary and secondary circuits, the flow heat transfer characteristics of the liquid metal and sCO2 in the main heat exchanger of the lead-cooled fast reactor and its coupled heat transfer performance are crucial to the power generation efficiency and safe operation of the fourth-generation nuclear power plant.

[0003] At present, some domestic scholars have conducted relevant research on the coupled heat exchange of liquid metal and sCO2 loop. For example, the application publication number is CN 113686918 A, and the name is liquid lead-bismuth alloy and SCO2 loop coupled heat transfer characteristics research experimental system. However, this system only studies the flow and heat transfer characteristics of liquid lead-bismuth alloy and supercritical carbon dioxide in the printed circuit board heat exchanger, and the pressure is relatively low, about 8PMa, and the temperature is about 200℃; the application publication number is CN 107327325 A, and the name is a supercritical carbon dioxide and liquid metal combined cycle system, its main purpose is to improve the thermal efficiency of the supercritical carbon dioxide cycle. Summary of the Invention

[0004] In order to overcome the problems existing in the above-mentioned prior art, the purpose of the present invention is to provide a multifunctional coupled heat exchange experimental system and method for liquid metal and supercritical fluid, which can carry out research on the coupled flow heat transfer characteristics of liquid metal and supercritical carbon dioxide with large temperature difference, large temperature span, and high variable heat flow under high temperature and high pressure conditions; it can also independently carry out research on the flow heat transfer characteristics of liquid metal coolant and supercritical carbon dioxide in different pipelines and experimental research on pipeline corrosion characteristics and natural circulation heat exchange characteristics under oxygen control conditions.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A multifunctional coupled heat exchange experimental system and method for liquid metal and supercritical fluid, comprising a liquid metal experimental loop and a supercritical carbon dioxide experimental loop; wherein:

[0007] The liquid metal experimental circuit includes: a first vacuum pump 3-1, an expansion tank 6, a melting tank 1, and an argon gas bottle 2 connected by a four-way connection, wherein the first gas valve 26-1, the second gas valve 26-2, and the third gas valve 26-3 are installed between the melting tank 1, the first vacuum pump 3-1, the expansion tank 6, and the four-way connection respectively; a melting tank temperature measuring device 19-1, a melting tank pressure measuring device 18-1, and a melting tank liquid level measuring device 20-1 are installed in the melting tank 1; the melting tank outlet is connected to the electric valve 4, the preheating section 5, the expansion tank 6, and the preheating section 5 inlet in sequence. A preheating section inlet temperature measuring device 19-2 is provided at the outlet of the preheating section 5, a preheating section outlet temperature measuring device 19-3 and a flange interface are provided at the outlet of the preheating section 5; a first heat trace 8-1 is attached to the pipeline between the preheating section 5 and the expansion tank 6; an expansion tank temperature measuring device 19-4 is provided inside the expansion tank 6, and the outlet of the expansion tank 6 is connected to the flange oxygen control interface, the first flow meter 7-1, and the calibration tank 9 in sequence, and a second heat trace 8-2 is attached to the pipeline between them, an expansion tank outlet temperature measuring device 19-5 is provided before the flange oxygen control interface, and a calibration tank 9 is provided after the first flow meter 7-1. The calibration tank 9 is provided with a calibration tank temperature measuring device 19-7 and a calibration tank liquid level measuring device 20-2; the calibration tank 9 outlet is connected to the regulating valve 10 and the tee, and the other two outlets of the tee are connected to the main heat exchanger 11 and the bypass respectively; the front and rear of the main heat exchanger 11 are flange interfaces, and the main heat exchanger liquid metal flow path inlet is provided with a third stop valve 12-3, a main heat exchanger liquid metal inlet pressure measuring device 18-2, and a main heat exchanger liquid metal inlet temperature measuring device 19-8. At the outlet of the liquid metal flow path of the main heat exchanger, the main heat exchanger liquid metal outlet temperature measuring device 19-9, the main heat exchanger liquid metal outlet pressure measuring device 18-3, and the first stop valve 12-1 are arranged in sequence, and intersect with the bypass pipeline. Then, there are the oil-cooled heat exchanger 13, the electromagnetic pump 17, the electromagnetic pump outlet temperature measuring device 19-10, the fourth stop valve 12-4, and the inlet of the preheating section 5. The oil-cooled heat exchanger 13, the oil tank 14, the oil pump 15, and the oil cooler 16 are connected in sequence to form an oil cooling system, and the front and back of the solenoid valve 17 are flange interfaces.

[0008] The supercritical carbon dioxide experimental circuit includes: a carbon dioxide bottle 21 is connected to a liquid storage tank 22, a fourth gas valve 26-4 is set at the outlet of the carbon dioxide bottle 21, the outlet of the liquid storage tank 22 is connected in sequence to the liquid storage tank outlet temperature measuring device 19-13, the fifth stop valve 12-5, the preheating and pressurizing system 23, the plunger pump 24, the main heat exchanger 11, and the cooling system 25, a second vacuum pump 3-2 is set between the cooling system 25 and the liquid storage tank 22; an eighth stop valve 12-8 is set at the outlet of the second vacuum pump; a sixth stop valve 12-6, a second stop valve 12-7, a second stop valve 12-8 are set at the inlet of the carbon dioxide flow path of the main heat exchanger 11 Meter 7-2, main heat exchanger supercritical carbon dioxide inlet temperature measuring device 19-12, main heat exchanger supercritical carbon dioxide inlet pressure measuring device 18-5, main heat exchanger supercritical carbon dioxide outlet temperature measuring device 19-11, main heat exchanger supercritical carbon dioxide outlet pressure measuring device 18-4, and seventh stop valve 12-7 are arranged in sequence at the outlet of the carbon dioxide flow path of the main heat exchanger 11; supercritical carbon dioxide cooling system outlet pressure measuring device 18-6, expansion tank temperature measuring device 19-14 and ninth stop valve 12-9 are arranged in sequence at the outlet of the cooling system 25.

[0009] The multifunctional coupled heat exchange experimental method of liquid metal and supercritical fluid includes experiments on the coupled flow and heat transfer characteristics of liquid metal and supercritical carbon dioxide, experiments on the corrosion of liquid metal pipelines, and experiments on the flow and heat transfer characteristics of liquid metal in reactor core fuel rod bundles.

[0010] The experiment on the coupled flow and heat transfer characteristics of liquid metal and supercritical carbon dioxide specifically includes the following steps:

[0011] Step 1: Before the experiment begins, the first vacuum pump 3-1 evacuates the liquid metal experimental circuit to expel air;

[0012] Step 2: Close the second gas valve 26-2 and the third gas valve 26-3, open the first gas valve 26-1 and the electric valve 4, the fourth stop valve 12-4, the first stop valve 12-1, the third stop valve 12-3, and the regulating valve 10, and fill the liquid metal experimental circuit with argon. Then, close all gas valves and stop valves, let it stand for a while, and check the airtightness of the experimental circuit by the changes in the readings of each pressure measuring device;

[0013] Step 3: After checking for airtightness, open the third air valve 26-3 to discharge the exhaust gas and re-evacuate the circuit;

[0014] Step 4: Heat the metal in the melting tank 1, monitor the melting status through the melting tank liquid level measuring device 20-1 and the melting tank temperature measuring device 19-1, and start the first heating pipeline 8-1 and the second heating pipeline 8-2;

[0015] Step 5: After the metal is completely melted, introduce argon gas to press the liquid metal into the circuit from the outlet at the bottom of the tank. Turn on the heating switch of the preheating section 5, close the regulating valve 10 below the calibration tank, and calibrate the first flowmeter 7-1 using the volume calibration method.

[0016] Step 6: After completing the flow calibration, open the regulating valve 10 below the calibration tank to allow the liquid metal in the calibration bypass to flow back to the melting tank 1. Continue to pressurize the liquid metal into the circuit until the circuit is full, and close the electric valve 4 at the liquid metal outlet of the melting tank 1.

[0017] Step 7: Simultaneously start the supercritical carbon dioxide experimental loop, and the second vacuum pump 3-2 evacuates the supercritical carbon dioxide experimental loop to exhaust the air;

[0018] Step 8: Close the eighth stop valve 12-8, open the fifth stop valve 12-5, the sixth stop valve 12-6, the seventh stop valve 12-7, the ninth stop valve 12-9, and the fourth gas valve 26-4, then close all the gas valves and stop valves, let it stand for a while, and check the air tightness of the experimental circuit by the changes in the readings of each pressure measuring device;

[0019] Step 9: After the air tightness check is complete, open the fourth air valve 26-4 to discharge the exhaust gas and re-evacuate the supercritical carbon dioxide experimental circuit;

[0020] Step 10: Open the carbon dioxide bottle 21 and feed the carbon dioxide into the bottom of the liquid storage tank 22. The amount of carbon dioxide fed into the supercritical carbon dioxide experimental circuit is measured by the second flow meter 7-2. After the carbon dioxide is fed, the fourth gas valve 26-4 is closed.

[0021] Step 11: Start the carbon dioxide preheating and pressurizing system 23 to pressurize the liquid carbon dioxide to a supercritical state, and raise the gas pressure in the liquid storage tank 22 to a predetermined pressure value;

[0022] Step 12: Simultaneously start the plunger pump 24 and the cooling system 25 to allow the carbon dioxide to fill the entire supercritical carbon dioxide experimental circuit;

[0023] Step 13: After the liquid metal solution and supercritical carbon dioxide meet the test requirements, open the fifth stop valve 12-5 and the sixth stop valve 12-6 to maintain the carbon dioxide pressure at 8-10 MPa, start preheating the carbon dioxide channel of the main heat exchanger, monitor the changes in the carbon dioxide temperature at the outlet of the main heat exchanger 11 and the changes in the metal temperature of the wall of the main heat exchanger 11, and when the wall metal temperature exceeds 360°C, the heat transfer test requirements are met;

[0024] Step 14: Adjust the regulating valve 10 to maintain the carbon dioxide pressure at 20-24 MPa; open the third stop valve 12-3 and the fourth stop valve 12-4 on the liquid metal pipeline side, close the oil-cooled heat exchanger 13, start the electromagnetic pump 17, and pump liquid metal to the main heat exchanger 11 to maintain the temperature of the liquid metal entering the heat exchanger at a constant value to facilitate test data analysis;

[0025] Step 15: The liquid metal in the calibration tank 9 is heat exchanged in the main heat exchanger 11 and then flows into the melting tank through the electromagnetic pump 17. The high-pressure gas in the liquid carbon dioxide storage tank 22 is heat exchanged in the main heat exchanger 11 and then enters the cooling system 25. After the pressure and temperature are reduced to the allowable values, it flows back to the storage tank 22. When the pressure and temperature values ​​are stable, one working condition test is considered to be completed.

[0026] Step 16: When the remaining liquid metal in the melting tank 1 is insufficient to conduct one experiment, the experiment is stopped, the electromagnetic pump 17 is turned off, the argon gas cylinder 2 is opened, and the liquid metal is pressed back into the melting tank 1 from the top of the expansion tank 6;

[0027] Step 17: When the remaining carbon dioxide in the carbon dioxide storage tank 22 is insufficient for a test, close the fifth stop valve 12-5 at the outlet of the storage tank 22, and use the plunger pump 24 to slowly pump the low-pressure gas in the supercritical carbon dioxide circuit into the carbon dioxide storage tank 22. Turn off the preheating and pressurizing system 23. When the temperature and pressure meet the test requirements, close the ninth stop valve 12-9 at the inlet of the storage tank 22.

[0028] Step 18: Carry out the test research of the next working condition according to the first test process;

[0029] Step 19: After the experimental system is stable, turn off the electromagnetic pump 17 to study the natural circulation flow and heat transfer characteristics of the liquid metal.

[0030] The liquid metal pipeline corrosion test specifically includes the following steps:

[0031] Step 1: Connect the oxygen control and oxygen concentration sensor to the flange interface at 6 of the expansion tank;

[0032] Step 2: Close the third stop valve 12-3 at the inlet and the first stop valve 12-1 at the outlet of the main heat exchanger of the liquid metal experimental loop, and connect the pipeline to be corroded through the bypass;

[0033] Step 3: The liquid metal experimental circuit leak detection, heating, and flow calibration are consistent with the liquid metal and supercritical carbon dioxide coupled flow and heat transfer characteristics experiment;

[0034] Step 4: Start the oxygen control and oxygen concentration sensor, and set the oxygen supply flow rate;

[0035] Step 5: After the liquid metal solution meets the test requirements, the second shut-off valve 12-2 and the regulating valve 10 of the bypass are opened, and the liquid lead flows through the corrosion pipeline;

[0036] Step 6: Start the oil-cooled heat exchanger 13 and the electromagnetic pump 17 to cool the liquid metal flowing through the corroded pipeline; after the pressure and temperature values ​​are stable, record the running time and consider that one working condition test is completed.

[0037] The experiment on the flow and heat transfer characteristics of liquid metal in the core fuel bundle specifically includes the following steps:

[0038] Step 1: Disconnect the main heat exchanger 11 and replace the original main heat exchanger 11 with the experimental section for arranging the core fuel rod bundles through the reserved pipe interface;

[0039] Step 2: The liquid metal experimental circuit leak detection, heating, pressurization, and flow calibration are consistent with the liquid metal and supercritical carbon dioxide coupled flow and heat transfer characteristics experiment;

[0040] Step 3: Adjust the preheating section 5 and regulating valve 10 to control the temperature and pressure of the metal flowing into the fuel rod bundle in the core. Then the oil-cooled heat exchanger 13 cools it and flows back to the electromagnetic pump 17. After the temperature and pressure parameters stabilize, the experimental study of one working condition is completed.

[0041] The experimental system of the present invention can not only conduct experimental research under high temperature and high pressure conditions, where the liquid metal temperature can reach 650°C, the supercritical carbon dioxide pressure can reach 24MPa, and the temperature can reach 560°C, but also conduct experimental research on the flow and heat transfer characteristics of liquid metal coolants (including liquid lead and lead-bismuth alloys) and supercritical carbon dioxide in pipelines, the coupled heat transfer characteristics of liquid metal and supercritical carbon dioxide, and the corrosion characteristics of liquid metal on pipelines under oxygen control conditions and natural circulation heat transfer characteristics. Compared with the existing technology, the present invention has the following advantages:

[0042] 1. The present invention has good safety performance. An electric valve is used at the outlet of the melting tank, which can remotely control the circuit switch. The expansion tank is set at the highest point and connected to the argon cylinder. At the end of the experiment, the liquid metal remaining in the circuit can be effectively purged to prevent the liquid metal from solidifying and clogging the pipeline.

[0043] 2. The liquid level measuring device in the calibration tank can effectively observe and control the flow of liquid metal in the experimental test circuit, ensuring sufficient experimental dosage while preventing excessive use of liquid metal.

[0044] 3. The present invention can be used to study the coupled flow and heat transfer characteristics of liquid heavy metal and supercritical carbon dioxide under conditions of large temperature difference, large temperature span, high variable heat flux, and high thermal stress under high temperature and high pressure conditions. At the same time, it can be used to study the natural circulation heat exchange characteristics, which makes up for the lack of experimental data on liquid lead in existing literature and is helpful to study the heat transfer mechanism and flow characteristics of liquid metal.

[0045] 4. This invention can observe the corrosion of pipelines after high-temperature liquid metal is processed, providing an experimental basis for further extending the working life of experimental equipment and optimizing corrosion resistance. It overcomes the shortcomings of existing inventions that cannot simultaneously study the corrosion of liquid metal.

[0046] 5. The present invention studies the flow and heat transfer characteristics of liquid metal in the core fuel rod bundle, and can also study the migration mechanism and distribution characteristics of oxygen in the non-isothermal operating environment of the core and its impact on the oxide layer on the pipe surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 Schematic diagram of the experimental system of the present invention.

[0048] 1 is the melting tank; 2 is the argon gas bottle; 3-1 is the first vacuum pump; 3-2 is the second vacuum pump; 4 is the electric valve; 4-1 is the melting tank level measuring device; 4-2 is the calibration tank level measuring device; 5 is the preheating section; 6 is the expansion tank; 7-1 is the first flow meter; 7-2 is the second flow meter; 8-1 is the first heating; 8-2 is the second heating; 9 is the calibration tank; 10 is the regulating valve; 11 is the main heat exchanger; 12-1 is the first stop valve; 12-2 is the second stop valve; 12-3 is the third stop valve; 12-4 is the fourth stop valve; 12-5 is the fifth stop valve; 1 2-6 is the sixth stop valve; 12-7 is the seventh stop valve; 12-8 is the eighth stop valve; 12-9 is the ninth stop valve; 13 is the oil-cooled heat exchanger; 14 is the oil tank; 15 is the oil pump; 16 is the oil cooler; 17 is the electromagnetic pump; 18-1 is the melting tank pressure measuring device; 18-2 is the main heat exchanger liquid metal inlet pressure measuring device; 18-3 is the main heat exchanger liquid metal outlet pressure measuring device; 18-4 is the main heat exchanger supercritical carbon dioxide outlet pressure measuring device; 18-5 is the main heat exchanger supercritical carbon dioxide inlet pressure measuring device; 18-6 is the supercritical carbon dioxide The outlet pressure measuring device of the carbon dioxide cooling system; 19-1 is the melting tank temperature measuring device; 19-2 is the preheating section inlet temperature measuring device; 19-3 is the preheating section outlet temperature measuring device; 19-4 is the expansion tank temperature measuring device; 19-5 is the expansion tank outlet temperature measuring device; 19-6 is the calibration tank inlet temperature measuring device; 19-7 is the calibration tank temperature measuring device; 19-8 is the main heat exchanger liquid metal inlet temperature measuring device; 19-9 is the main heat exchanger liquid metal outlet temperature measuring device; 19-10 is the electromagnetic pump outlet temperature measuring device; 19-11 19-12 is the main heat exchanger supercritical carbon dioxide outlet temperature measuring device; 19-13 is the liquid storage tank outlet temperature measuring device; 19-14 is the cooling system outlet temperature measuring device; 20-1 is the melting tank liquid level measuring device; 20-2 is the calibration tank liquid level measuring device; 21 is the carbon dioxide bottle; 22 is the liquid storage tank; 23 is the preheating and boosting system; 24 is the plunger pump; 25 is the cooling system; 26-1 is the first gas valve; 26-2 is the second gas valve; 26-3 is the third gas valve; 26-4 is the fourth gas valve;. DETAILED DESCRIPTION

[0049] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0050] like Figure 1 As shown, the liquid metal and supercritical carbon dioxide multifunctional coupling heat exchange experimental system and method of the present invention include a liquid metal experimental circuit and a supercritical carbon dioxide experimental circuit; wherein:

[0051] The liquid metal experimental circuit includes: a first vacuum pump 3-1, an expansion tank 6, a melting tank 1, and an argon gas bottle 2 connected by a four-way connection, wherein the first gas valve 26-1, the second gas valve 26-2, and the third gas valve 26-3 are installed between the melting tank 1, the first vacuum pump 3-1, the expansion tank 6, and the four-way connection respectively; a melting tank temperature measuring device 19-1, a melting tank pressure measuring device 18-1, and a melting tank liquid level measuring device 20-1 are installed in the melting tank 1; the melting tank outlet is connected to the electric valve 4, the preheating section 5, the expansion tank 6, and the preheating section 5 inlet in sequence. A preheating section inlet temperature measuring device 19-2 is provided at the outlet of the preheating section 5, a preheating section outlet temperature measuring device 19-3 and a flange interface are provided at the outlet of the preheating section 5; a first heat trace 8-1 is attached to the pipeline between the preheating section 5 and the expansion tank 6; an expansion tank temperature measuring device 19-4 is provided inside the expansion tank 6, and the outlet of the expansion tank 6 is connected to the flange oxygen control interface, the first flow meter 7-1, and the calibration tank 9 in sequence, and a second heat trace 8-2 is attached to the pipeline between them, an expansion tank outlet temperature measuring device 19-5 is provided before the flange oxygen control interface, and a calibration tank 9 is provided after the first flow meter 7-1. The calibration tank 9 is provided with a calibration tank temperature measuring device 19-7 and a calibration tank liquid level measuring device 20-2; the calibration tank 9 outlet is connected to the regulating valve 10 and the tee, and the other two outlets of the tee are connected to the main heat exchanger 11 and the bypass respectively; the front and rear of the main heat exchanger 11 are flange interfaces, and the main heat exchanger liquid metal flow path inlet is provided with a third stop valve 12-3, a main heat exchanger liquid metal inlet pressure measuring device 18-2, and a main heat exchanger liquid metal inlet temperature measuring device 19-8. At the outlet of the liquid metal flow path of the main heat exchanger, the main heat exchanger liquid metal outlet temperature measuring device 19-9, the main heat exchanger liquid metal outlet pressure measuring device 18-3, and the first stop valve 12-1 are arranged in sequence, and intersect with the bypass pipeline. Then, there are the oil-cooled heat exchanger 13, the electromagnetic pump 17, the electromagnetic pump outlet temperature measuring device 19-10, the fourth stop valve 12-4, and the inlet of the preheating section 5. The oil-cooled heat exchanger 13, the oil tank 14, the oil pump 15, and the oil cooler 16 are connected in sequence to form an oil cooling system, and the front and back of the solenoid valve 17 are flange interfaces.

[0052] The supercritical carbon dioxide experimental circuit includes: a carbon dioxide bottle 21 is connected to a liquid storage tank 22, a fourth gas valve 26-4 is set at the outlet of the carbon dioxide bottle 21, the outlet of the liquid storage tank 22 is connected in sequence to the liquid storage tank outlet temperature measuring device 19-13, the fifth stop valve 12-5, the preheating and pressurizing system 23, the plunger pump 24, the main heat exchanger 11, and the cooling system 25, a second vacuum pump 3-2 is set between the cooling system 25 and the liquid storage tank 22; an eighth stop valve 12-8 is set at the outlet of the second vacuum pump; a sixth stop valve 12-6, a second stop valve 12-7, a second stop valve 12-8 are set at the inlet of the carbon dioxide flow path of the main heat exchanger 11 Meter 7-2, main heat exchanger supercritical carbon dioxide inlet temperature measuring device 19-12, main heat exchanger supercritical carbon dioxide inlet pressure measuring device 18-5, main heat exchanger supercritical carbon dioxide outlet temperature measuring device 19-11, main heat exchanger supercritical carbon dioxide outlet pressure measuring device 18-4, and seventh stop valve 12-7 are arranged in sequence at the outlet of the carbon dioxide flow path of the main heat exchanger 11; supercritical carbon dioxide cooling system outlet pressure measuring device 18-6, expansion tank temperature measuring device 19-14 and ninth stop valve 12-9 are arranged in sequence at the outlet of the cooling system 25.

[0053] The present invention is a multifunctional coupled heat exchange experimental system and method for liquid metal and supercritical fluid. The liquid metal experimental loop and the supercritical carbon dioxide experimental loop can be coupled to carry out flow heat exchange experiments and flow heat exchange experiments under natural circulation. Compared with traditional systems, this system has the characteristics of large temperature difference, large temperature span, high variable heat flow, and high thermal stress. In addition, the liquid metal experimental loop can also independently carry out flow heat transfer characteristics experiments of liquid heavy metal coolant and supercritical carbon dioxide in different pipelines, liquid metal pipeline corrosion experimental research, and flow and heat transfer characteristics research of liquid metal in core fuel rod bundles.

[0054] 1. Experiment on the coupled flow and heat transfer characteristics of liquid metal and supercritical carbon dioxide

[0055] Step 1: Before the experiment begins, the first vacuum pump 3-1 evacuates the liquid metal experimental circuit to expel air;

[0056] Step 2: Close the second gas valve 26-2 and the third gas valve 26-3, open the first gas valve 26-1 and the electric valve 4, the fourth stop valve 12-4, the first stop valve 12-1, the third stop valve 12-3, and the regulating valve 10, and fill the liquid metal experimental circuit with argon. Then, close all gas valves and stop valves, let it stand for a while, and check the airtightness of the experimental circuit by the changes in the readings of each pressure measuring device;

[0057] Step 3: After checking for airtightness, open the third air valve 26-3 to discharge the exhaust gas and re-evacuate the circuit;

[0058] Step 4: Heat the lead block in the melting tank 1 (from room temperature to 360°C), monitor the melting status through the melting tank liquid level measuring device 20-1 and the melting tank temperature measuring device 19-1, and start the first heating line 8-1 and the second heating line 8-2;

[0059] Step 5: After the lead block is completely melted, introduce argon gas to press the liquid lead into the circuit from the outlet at the bottom of the tank. Turn on the heating switch of the preheating section 5 (gradually increase the heating power until the liquid lead temperature reaches 600°C). Close the regulating valve 10 below the calibration tank and calibrate the first flowmeter 7-1 using the volume calibration method.

[0060] Step 6: After completing the flow calibration, open the regulating valve 10 below the calibration tank to allow the liquid lead in the calibration bypass to flow back to the melting tank 1. Continue to pressurize the liquid lead into the circuit until the circuit is full. Close the electric valve 4 at the liquid lead outlet of the melting tank 1.

[0061] Step 7: Simultaneously start the supercritical carbon dioxide experimental loop, and the second vacuum pump 3-2 evacuates the supercritical carbon dioxide experimental loop to exhaust the air;

[0062] Step 8: Close the eighth stop valve 12-8, open the fifth stop valve 12-5, the sixth stop valve 12-6, the seventh stop valve 12-7, the ninth stop valve 12-9, and the fourth gas valve 26-4, then close all the gas valves and stop valves, let it stand for a while, and check the air tightness of the experimental circuit by the changes in the readings of each pressure measuring device;

[0063] Step 9: After the air tightness check is complete, open the fourth air valve 26-4 to discharge the exhaust gas and re-evacuate the supercritical carbon dioxide experimental circuit;

[0064] Step 10: Open the carbon dioxide bottle 21 and feed the carbon dioxide into the bottom of the liquid storage tank 22. The amount of carbon dioxide fed into the supercritical carbon dioxide experimental circuit is measured by the second flow meter 7-2. After the carbon dioxide is fed, the fourth gas valve 26-4 is closed.

[0065] Step 11: Start the carbon dioxide preheating and pressurizing system 23 to pressurize the liquid carbon dioxide to a supercritical state, and raise the gas pressure in the liquid storage tank 22 to a predetermined pressure value;

[0066] Step 12: Simultaneously start the plunger pump 24 and the cooling system 25 to allow the carbon dioxide to fill the entire supercritical carbon dioxide experimental circuit;

[0067] Step 13: After both the liquid lead solution and the supercritical carbon dioxide meet the test requirements, open the fifth stop valve 12-5 and the sixth stop valve 12-6 to maintain the carbon dioxide pressure at 8-10 MPa. Preheat the carbon dioxide channel of the main heat exchanger and monitor changes in the carbon dioxide temperature at the outlet of the main heat exchanger 11 and the metal temperature of the wall of the main heat exchanger 11. When the wall metal temperature exceeds 360°C, the heat transfer test requirements are met.

[0068] Step 14: Adjust the regulating valve 10 to maintain the carbon dioxide pressure at 20-24 MPa; open the third stop valve 12-3 and the fourth stop valve 12-4 on the liquid lead pipeline side, close the oil-cooled heat exchanger 13, and start the electromagnetic pump 17 to pump liquid lead into the main heat exchanger 11, maintaining the temperature of the liquid lead entering the heat exchanger at a constant value to facilitate test data analysis;

[0069] Step 15: The liquid lead in the calibration tank 9 is heated by the main heat exchanger 11 and then flows into the melting tank through the electromagnetic pump 17. The high-pressure gas in the liquid carbon dioxide storage tank 22 is heated by the main heat exchanger 11 and then enters the cooling system 25. After the pressure and temperature are reduced to the allowable values, it flows back to the storage tank 22. When the pressure and temperature values ​​are stable, one working condition test is considered to be completed.

[0070] Step 16: When the remaining liquid lead in the melting tank 1 is insufficient to conduct one experiment, the experiment is stopped, the electromagnetic pump 17 is turned off, the argon gas cylinder 2 is opened, and the liquid lead is pressed back into the melting tank 1 from the top of the expansion tank 6;

[0071] Step 17: When the remaining carbon dioxide in the carbon dioxide storage tank 22 is insufficient for a test, close the fifth stop valve 12-5 at the outlet of the storage tank 22, and use the plunger pump 24 to slowly pump the low-pressure gas in the supercritical carbon dioxide circuit into the carbon dioxide storage tank 22. Turn off the preheating and pressurizing system 23. When the temperature and pressure meet the test requirements, close the ninth stop valve 12-9 at the inlet of the storage tank 22.

[0072] Step 18: Carry out the test research of the next working condition according to the first test process;

[0073] Step 19: After the experimental system is stable, turn off the electromagnetic pump 17 to study the natural circulation flow and heat transfer characteristics of liquid lead.

[0074] 2. Liquid metal pipeline corrosion test

[0075] Step 1: Connect the oxygen control and oxygen concentration sensor to the flange interface at 6 of the expansion tank;

[0076] Step 2: Close the third stop valve 12-3 at the inlet and the first stop valve 12-1 at the outlet of the main heat exchanger of the liquid metal experimental loop, and connect the pipeline to be corroded through the bypass;

[0077] Step 3: The liquid metal experimental circuit leak detection, heating, flow calibration and liquid metal and supercritical carbon dioxide coupled flow heat transfer characteristics experiment are consistent;

[0078] Step 4: Start the oxygen control and oxygen concentration sensor, and set the oxygen supply flow rate;

[0079] Step 5: After the liquid lead solution meets the test requirements, the second shut-off valve 12-2 and the regulating valve 10 of the bypass are opened, and the liquid lead flows through the corrosion pipeline;

[0080] Step 6: Start the oil-cooled heat exchanger 13 and electromagnetic pump 17 to cool the liquid lead flowing through the corroded pipeline. After the pressure and temperature values ​​stabilize, record the running time and consider the test condition complete.

[0081] 3. Experiment on the flow and heat transfer characteristics of liquid metal in the core fuel bundle

[0082] Step 1: Disconnect the main heat exchanger 11 and replace the original main heat exchanger 11 with the experimental section for arranging the core fuel rod bundles through the reserved pipe interface;

[0083] Step 2: The liquid metal experimental circuit leak detection, heating, pressurization, and flow calibration are consistent with the liquid metal supercritical carbon dioxide coupled flow and heat transfer characteristics experiment;

[0084] Step 3: Adjust the preheating section 5 and the regulating valve 10 to control the temperature and pressure of the lead flowing into the core fuel rod bundle. Then the lead flows back to the electromagnetic pump 17 after cooling through the oil-cooled heat exchanger 13. After the temperature and pressure parameters stabilize, the experimental study of one working condition is completed.

[0085] The use and operation of the system loop have proved that the experimental system loop design of the present invention is reasonable and the operation is safe. It can complete the flow heat transfer experiment of the liquid metal experimental loop and the supercritical carbon dioxide loop coupling, the flow heat transfer experiment under natural circulation, the flow and heat transfer characteristics experiment of liquid metal coolant and supercritical carbon dioxide in different pipelines, the liquid metal pipeline corrosion experimental research, and the flow and heat transfer characteristics research of liquid metal in the core fuel rod bundle.

[0086] The above content is a further detailed description of the present invention in combination with specific preferred embodiments. It cannot be considered that the specific embodiments of the present invention are limited to these. For ordinary technicians in the technical field to which the present invention belongs, they can make several simple deductions or substitutions without departing from the concept of the present invention, which should be regarded as belonging to the scope of patent protection determined by the submitted claims of the present invention.

Claims

1. Liquid metal and supercritical fluid multifunctional coupling heat exchange experimental system, characterized by: The experimental system includes a liquid metal experimental loop and a supercritical carbon dioxide experimental loop. It can carry out research on the coupled flow and heat transfer characteristics of liquid metal and supercritical carbon dioxide under high temperature and high pressure conditions with large temperature differences, large temperature spans, and high variable heat fluxes. It can also independently carry out research on the flow and heat transfer characteristics of liquid heavy metal coolants and supercritical carbon dioxide in different pipelines, as well as experimental research on pipeline corrosion characteristics and natural circulation heat transfer characteristics under oxygen control conditions. Among them: The liquid metal experimental circuit comprises: a first vacuum pump (3-1), an expansion tank (6), a melting tank (1), and an argon gas bottle (2) connected through a four-way connection, wherein a first gas valve (26-1), a second gas valve (26-2), and a third gas valve (26-3) are respectively installed between the melting tank (1), the first vacuum pump (3-1), the expansion tank (6), and the four-way connection; a melting tank temperature measuring device (19-1), a melting tank pressure measuring device (18-1), and a melting tank liquid level measuring device (20-1) are provided in the melting tank (1); and an outlet of the melting tank is sequentially connected to an electric valve (4), a preheating section (5), and an expansion tank (6). A preheating section inlet temperature measuring device (19-2) is provided at the inlet of the preheating section (5), and a preheating section outlet temperature measuring device (19-3) and a flange interface are provided at the outlet of the preheating section (5); a first heat tracer (8-1) is attached to the pipeline between the preheating section (5) and the expansion box (6); an expansion box temperature measuring device (19-4) is provided in the expansion box (6), and the outlet of the expansion box (6) is connected to the flange oxygen control interface, the first flow meter (7-1), and the calibration tank (9) in sequence, and a second heat tracer (8-2) is attached to the pipeline between them; an expansion box outlet temperature measuring device (19-5) is provided in front of the flange oxygen control interface, the first flow meter (7-1), and the calibration tank (9) -1) is provided with a calibration tank inlet temperature measuring device (19-6); a calibration tank temperature measuring device (19-7) and a calibration tank liquid level measuring device (20-2) are provided in the calibration tank (9); the outlet of the calibration tank (9) is connected to a regulating valve (10) and a tee, and the other two outlets of the tee are connected to the main heat exchanger (11) and the bypass respectively; the front and rear of the main heat exchanger (11) are flange interfaces, and the inlet of the liquid metal flow path of the main heat exchanger is provided with a third stop valve (12-3), a main heat exchanger liquid metal inlet pressure measuring device (18-2), a main heat exchanger liquid metal inlet temperature measuring device (19-8) and a main heat exchanger liquid metal inlet temperature measuring device (19-9) in sequence. ), the main heat exchanger liquid metal outlet temperature measuring device (19-9), the main heat exchanger liquid metal outlet pressure measuring device (18-3), and the first stop valve (12-1) are sequentially arranged at the outlet of the main heat exchanger liquid metal flow path, and intersect with the bypass pipeline, followed by the oil-cooled heat exchanger (13), the electromagnetic pump (17), the electromagnetic pump outlet temperature measuring device (19-10), the fourth stop valve (12-4), and the preheating section (5) inlet, the oil-cooled heat exchanger (13), the oil tank (14), the oil pump (15), and the oil cooler (16) are sequentially connected to form an oil cooling system, and the front and rear of the electromagnetic pump (17) are flange interfaces; The supercritical carbon dioxide experimental circuit comprises: a carbon dioxide bottle (21) is connected to a liquid storage tank (22); a fourth gas valve (26-4) is provided at the outlet of the carbon dioxide bottle (21); the outlet of the liquid storage tank (22) is connected in sequence to a liquid storage tank outlet temperature measuring device (19-13), a fifth stop valve (12-5), a preheating and pressure-boosting system (23), a plunger pump (24), a main heat exchanger (11), and a cooling system (25); a second vacuum pump (3-2) is provided between the cooling system (25) and the liquid storage tank (22); an eighth stop valve (12-8) is provided at the outlet of the second vacuum pump; a sixth stop valve (12-13) is provided at the inlet of the carbon dioxide flow path of the main heat exchanger (11); and a sixth stop valve (12-14) is provided at the inlet of the carbon dioxide flow path of the main heat exchanger (11). -6), a second flow meter (7-2), a main heat exchanger supercritical carbon dioxide inlet temperature measuring device (19-12), a main heat exchanger supercritical carbon dioxide inlet pressure measuring device (18-5), a main heat exchanger supercritical carbon dioxide outlet temperature measuring device (19-11), a main heat exchanger supercritical carbon dioxide outlet pressure measuring device (18-4), and a seventh stop valve (12-7) are sequentially arranged at the outlet of the carbon dioxide flow path of the main heat exchanger (11); a supercritical carbon dioxide cooling system outlet pressure measuring device (18-6), an expansion tank temperature measuring device (19-4), and a ninth stop valve (12-9) are sequentially arranged at the outlet of the cooling system (25).

2. The multifunctional coupled heat exchange experimental system of liquid metal and supercritical fluid according to claim 1 is characterized by: The argon cylinder (2) is connected to the melting tank (1) and the expansion tank (6) to press all the liquid metal into the experimental circuit at the beginning of the experiment, and to press the liquid metal from the top expansion tank (6) back into the melting tank (1) at the end of the experiment to prevent the experimental circuit from being blocked.

3. The multifunctional coupled heat exchange experimental system of liquid metal and supercritical fluid according to claim 1 is characterized by: An oxygen control interface is reserved at the expansion tank (6). After disconnecting the main heat exchanger (11), the corrosion pipeline is connected as the experimental section. An oxygen concentration sensor is set in the expansion tank (6) to study the phenomenon and mechanism of oxygen corrosion on liquid metal pipelines.

4. The multifunctional coupled heat exchange experimental system of liquid metal and supercritical fluid according to claim 1 is characterized by: The connection of the main heat exchanger (11) is disconnected, and the original heat exchanger is transformed into an experimental section for arranging the core fuel rod bundle through the reserved pipe interface.

5. The multifunctional coupled heat exchange experimental system of liquid metal and supercritical fluid according to claim 1 is characterized in that: Disassembling the electromagnetic pump (17) enables the liquid metal natural circulation experimental research to be carried out, including the natural circulation steady-state experiment and the transient experiment.

6. The experimental method of the liquid metal and supercritical fluid multifunctional coupled heat exchange experimental system according to any one of claims 1 to 5, characterized in that: Including experiments on the coupled flow and heat transfer characteristics of liquid metal and supercritical carbon dioxide, experiments on the corrosion of liquid metal pipelines, and experiments on the flow and heat transfer characteristics of liquid metal in the core fuel bundle; The experiment on the coupled flow and heat transfer characteristics of liquid metal and supercritical carbon dioxide specifically includes the following steps: Step 1: Before the experiment begins, the first vacuum pump (3-1) evacuates the liquid metal experimental circuit to remove air; Step 2: Close the second gas valve (26-2) and the third gas valve (26-3), open the first gas valve (26-1) and the electric valve (4), the fourth stop valve (12-4), the first stop valve (12-1), the third stop valve (12-3), and the regulating valve (10), fill the liquid metal experimental circuit with argon gas, then close all the gas valves and stop valves, let it stand for a period of time, and check the airtightness of the experimental circuit by the changes in the readings of each pressure measuring device; Step 3: After checking the air tightness and finding no problems, open the third air valve (26-3) to discharge the exhaust gas and re-evacuate the circuit; Step 4: heating the metal in the melting tank (1), monitoring the melting condition through the melting tank liquid level measuring device (20-1) and the melting tank temperature measuring device (19-1), and starting the first heating (8-1) and the second heating (8-2) of the pipeline; Step 5: After the metal is completely melted, introduce argon gas to press the liquid metal into the circuit from the outlet at the bottom of the tank, turn on the heating switch of the preheating section (5), close the regulating valve (10) below the calibration tank, and calibrate the first flow meter (7-1) using the volume calibration method; Step 6: After completing the flow calibration, open the regulating valve (10) below the calibration tank to allow the liquid metal in the calibration bypass to flow back to the melting tank (1), continue to pressurize the liquid metal into the circuit until the circuit is full, and close the electric valve (4) at the liquid metal outlet of the melting tank (1); Step 7: Simultaneously start the supercritical carbon dioxide experimental loop, and the second vacuum pump (3-2) evacuates the supercritical carbon dioxide experimental loop to exhaust the air; Step 8: Close the eighth stop valve (12-8), open the fifth stop valve (12-5), the sixth stop valve (12-6), the seventh stop valve (12-7), the ninth stop valve (12-9), and the fourth gas valve (26-4), then close all the gas valves and stop valves, let it stand for a while, and check the air tightness of the experimental circuit by the changes in the readings of each pressure measuring device; Step 9: After the air tightness check is complete, open the fourth air valve (26-4) to discharge the waste gas and re-evacuate the supercritical carbon dioxide experimental circuit; Step 10: Open the carbon dioxide bottle (21) and feed the carbon dioxide into the bottom of the liquid storage tank (22). The amount of carbon dioxide fed into the supercritical carbon dioxide experimental circuit is measured by the second flow meter (7-2). After the carbon dioxide is fed, the fourth gas valve (26-4) is closed. Step 11: Start the carbon dioxide preheating and pressurizing system (23), pressurize the liquid carbon dioxide to a supercritical state, and raise the gas pressure in the liquid storage tank (22) to a predetermined pressure value; Step 12: Simultaneously start the plunger pump (24) and the cooling system (25) so that the carbon dioxide fills the entire supercritical carbon dioxide experimental circuit; Step 13: After the liquid metal solution and supercritical carbon dioxide meet the test requirements, open the fifth stop valve (12-5) and the sixth stop valve (12-6) to maintain the carbon dioxide pressure at 8-10 MPa, start preheating the carbon dioxide channel of the main heat exchanger, monitor the changes in the carbon dioxide temperature at the outlet of the main heat exchanger (11) and the changes in the metal temperature of the wall of the main heat exchanger (11), and when the wall metal temperature exceeds 360°C, the heat transfer test requirements are met; Step 14: Adjust the regulating valve (10) to maintain the carbon dioxide pressure at 20-24 MPa; Open the third stop valve (12-3) and the fourth stop valve (12-4) on the liquid metal pipeline side, close the oil-cooled heat exchanger (13) at the same time, start the electromagnetic pump (17), and pump the liquid metal to the main heat exchanger (11), so as to maintain the temperature of the liquid metal entering the heat exchanger at a constant value, so as to facilitate the analysis of the test data; Step 15: The liquid metal in the calibration tank (9) is heat exchanged in the main heat exchanger (11) and then flows into the melting tank through the electromagnetic pump (17); the high-pressure gas in the liquid carbon dioxide storage tank (22) is heat exchanged in the main heat exchanger (11) and then enters the cooling system (25). After the pressure and temperature are reduced to the allowable values, it flows back to the storage tank (22); when the pressure and temperature values ​​are stable, it is considered that one working condition test is completed; Step 16: When the amount of liquid metal remaining in the melting tank (1) is insufficient for one experiment, the experiment is stopped, the electromagnetic pump (17) is turned off, the argon gas bottle (2) is opened, and the liquid metal is pressed back into the melting tank (1) from the top of the expansion tank (6); Step 17: When the remaining carbon dioxide in the carbon dioxide storage tank (22) is insufficient for one test, close the fifth stop valve (12-5) at the outlet of the storage tank (22), use the plunger pump (24) to slowly pump the low-pressure gas in the supercritical carbon dioxide circuit into the carbon dioxide storage tank (22), close the preheating and pressurizing system (23), and when the temperature and pressure meet the test requirements, close the ninth stop valve (12-9) at the inlet of the storage tank (22); Step 18: Carry out the test research of the next working condition according to the first test process; Step 19: After the experimental system is stable, turn off the electromagnetic pump (17) to study the natural circulation flow and heat transfer characteristics of the liquid metal; The liquid metal pipeline corrosion test specifically includes the following steps: Step 1: Connect the oxygen control and oxygen concentration sensor to the flange interface of the expansion tank (6); Step 2: Close the third stop valve (12-3) at the inlet and the first stop valve (12-1) at the outlet of the main heat exchanger of the liquid metal experimental loop, and connect the pipeline to be corroded through the bypass; Step 3: The liquid metal experimental circuit leak detection, heating, and flow calibration are consistent with the liquid metal and supercritical carbon dioxide coupled flow and heat transfer characteristics experiment; Step 4: Start the oxygen control and oxygen concentration sensor, and set the oxygen supply flow rate; Step 5: After the liquid metal solution meets the test requirements, the second stop valve (12-2) and the regulating valve (10) of the bypass are opened, and the liquid lead flows through the corrosion pipeline; Step 6: Start the oil-cooled heat exchanger (13) and the electromagnetic pump (17) to cool the liquid metal flowing through the corroded pipeline; after the pressure and temperature values ​​are stable, record the running time and consider that one working condition test is completed; The experiment on the flow and heat transfer characteristics of liquid metal in the core fuel bundle specifically includes the following steps: Step 1: Disconnect the main heat exchanger (11) and replace the original main heat exchanger (11) with the experimental section of the core fuel rod bundle arrangement through the reserved pipe interface; Step 2: The liquid metal experimental circuit leak detection, heating, pressurization, and flow calibration are consistent with the liquid metal and supercritical carbon dioxide coupled flow and heat transfer characteristics experiment; Step 3: Regulate the preheating section (5) and the regulating valve (10) to control the temperature and pressure of the metal flowing into the fuel rod bundle in the core, and then flow back to the electromagnetic pump (17) after cooling through the oil-cooled heat exchanger (13). After the temperature and pressure parameters are stabilized, the experimental study of one working condition is completed.

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