A test system and method for testing thermal performance of a heat exchanger of an intermittent operation fusion device

Abstract

The application discloses a kind of heat transfer performance test system and method of intermittent operation heat exchanger of fusion device, belong to the technical field of performance detection of fusion device energy storage system core equipment, including lithium lead filling and circulating loop, argon protection branch, molten salt circulating loop and measurement control system.Simulate fusion reactor intermittent operating condition by periodic start-stop (operation time t1+stop time t2), adjust the inlet temperature of air cooler by bypass mixing branch, and realize automatic control and data acquisition by PLC.The test method judges "intermittent steady state" by multi-cycle operation, and calculates the average resistance drop, heat transfer temperature difference and total heat transfer coefficient of heat exchanger based on steady-state data.The application fills the technical gap of high-temperature liquid metal intermittent operation heat exchanger performance test.

Description

Technical Field

[0001] This invention belongs to the field of core equipment performance testing technology for fusion device energy storage systems, specifically relating to a thermal performance testing system and method for intermittent operation heat exchangers of fusion devices. Background Technology

[0002] With the development of controlled nuclear fusion energy technology, fusion reactors, as advanced energy devices with high energy density, low carbon emissions, and high safety, are gradually moving from the physical experiment stage to the engineering demonstration and commercial application stage. In fusion reactor energy utilization systems, the high-grade thermal energy generated by fusion plasma typically needs to be recovered and utilized through energy conversion systems. Among these systems, energy storage systems, as a key intermediate link connecting the heat source and the downstream power generation system, can resolve the contradiction between the intermittent operation of the fusion reactor and the power generation system's demand for a stable heat source, thus helping to improve system stability and reliable operating life.

[0003] The thermal storage heat exchanger is a core component of the fusion reactor thermal storage system. Located between the fusion reactor heat source and the molten salt storage tank, it transfers the heat generated during fusion reactor operation to the molten salt for storage. The hot-side medium of the thermal storage heat exchanger for fusion reactors includes high-temperature liquid LiPb, supercritical CO2, and helium. LiPb, in particular, facilitates the breeding of tritium fuel, making it more suitable as the primary coolant for the fusion reactor blanket heat source. The cold-side medium is the thermal storage molten salt. The thermal storage heat exchanger is characterized by intermittent operation and high operating temperatures. Its intermittent thermal performance directly affects the efficiency of heat transfer from the fusion reactor to the molten salt, significantly impacting the overall thermal storage efficiency of the system.

[0004] Currently, existing technologies mainly focus on the thermal performance testing of conventional heat exchangers, with simple cold and hot side media, generally water, air, refrigerant, or oil. A few patented technologies involve molten salt media, such as Chinese patent application CN201510918131.2 (a performance testing device for molten salt heat exchange and storage equipment) and Chinese patent application CN202421489463.4 (a performance testing platform for low-energy molten salt microchannel heat exchangers supporting long-term operation). However, these technologies are only applicable to molten salt and thermal oil media, and are not suitable for high-temperature lithium-lead media with certain pressure, and cannot achieve the circulation of lithium-lead media. Furthermore, existing thermal performance testing methods do not cover the performance testing process of intermittently operating heat exchangers, leaving the testing and evaluation of intermittent operation performance of heat exchangers completely unexplored. Although Chinese patent application CN202110818483.6 (a test system and test method for an unsteady heat source heat exchanger) mentions an unsteady heat source, this technology achieves heat source temperature control by mixing high and low temperature fluids, and cannot achieve intermittent operation of the heat source medium.

[0005] In summary, lithium-lead-molten salt thermal energy exchangers are core components of fusion reactor thermal energy storage systems. Their thermal performance directly impacts the efficiency of the entire system and the power generation output. Currently, industry focus is largely on testing the thermal performance of conventional heat exchangers. Conventional heat exchangers use simple media on the cold and hot sides, typically water, air, refrigerant, or oil, and do not involve high-temperature liquid LiPb media. Existing experimental platforms cannot test LiPb heat exchangers in the fusion reactor field. Furthermore, the operating conditions are intermittent, and existing thermal performance testing methods are designed for stable operation, making them unsuitable for intermittent operation. Therefore, there is an urgent need for a system and testing method capable of testing the thermal performance of intermittently operating heat exchangers, providing reliable experimental evidence and data support for the design optimization and operational strategy formulation of fusion reactor thermal energy storage heat exchangers. Summary of the Invention

[0006] To address the limitations of existing technologies in performance testing and evaluation of intermittent operation performance of lithium-lead heat exchangers for fusion reactors, this invention provides a system and method for testing the thermal performance of intermittently operating heat exchangers in fusion devices. This system tests and evaluates the thermal performance of intermittently operating heat exchangers, making it applicable to high-temperature liquid metal operating conditions such as lithium and lead. This invention can be used to test the thermal performance of lithium-lead-molten salt thermal storage heat exchangers for fusion reactors, simulate intermittent operation conditions, and evaluate the heat transfer coefficient and drag drop of intermittently operating heat exchangers, playing a crucial role in improving the performance of thermal storage heat exchangers for fusion devices.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A thermal performance testing system for an intermittently operating heat exchanger of a fusion device includes a lithium-lead filling and circulation loop for providing the hot-side circulating medium, an argon protection branch for maintaining an inert atmosphere, a molten salt circulation loop for providing the cold-side circulating medium, and a measurement and control system for acquiring data and controlling operation. The lithium-lead filling and circulation loop includes the heat exchanger under test, whose hot-side outlet is sequentially connected to a first pump for driving the lithium-lead flow, a first valve, an electric heater for heating the lithium-lead, and a second valve. The outlet of the second valve is connected to the hot-side inlet of the heat exchanger under test. An expansion tank is connected to the pipeline between the electric heater and the second valve to accommodate volume expansion. The lithium-lead storage tank is connected to... The pipeline is connected to the third valve and the second pump for replenishing the liquid. The fourth valve connects the lowest point of the lithium-lead circulation loop to the lithium-lead storage tank to achieve venting. The argon protection branch includes a high-pressure argon cylinder, which is split into two paths after passing through the fifth and sixth valves. These paths supply gas to the gas phase space of the lithium-lead storage tank and the expansion tank through the seventh and eighth valves, respectively. The molten salt circulation loop includes a molten salt storage tank. Its outlet is split into two paths after passing through the ninth valve and the third pump for driving the molten salt. One path connects to the cold side inlet of the heat exchanger under test, and the other path forms a bypass mixing branch through the tenth valve. The cold side outlet of the heat exchanger under test merges with the bypass mixing branch and returns to the molten salt storage tank through the air cooler used for cooling.

[0009] This invention also provides a method for testing the thermal performance of a heat exchanger during intermittent operation of a fusion device, based on the aforementioned system for testing the thermal performance of a heat exchanger during intermittent operation of a fusion device, comprising the following steps:

[0010] Preheating lithium-lead storage tanks, molten salt storage tanks and pipelines;

[0011] Fill the lithium-lead filling and circulation loops and the molten salt circulation loops with the medium and establish the initial pressure;

[0012] Open the lithium-lead circulation loop and the molten salt circulation loop, adjust the hot side flow rate to the set value and start the electric heater to make the hot side medium reach the set temperature. At the same time, adjust the cold side flow rate to the set value and control the air cooler to maintain its outlet temperature constant.

[0013] The lithium-lead circulation loop and the molten salt circulation loop are controlled to run continuously during the running time t1 and paused during the stopping time t2, which constitutes a test cycle time t = t1 + t2; t1 is the running time and t2 is the pause time; the test cycle time is repeated for no less than three test cycles.

[0014] The average resistance drop, average temperature difference, and overall heat transfer coefficient on the hot and cold sides of the lithium-lead and molten salt circulation loops are calculated to evaluate the thermal performance of the heat exchangers under test.

[0015] Beneficial effects:

[0016] 1. This invention is the first to construct a thermal performance testing system for intermittently operating heat exchangers that is compatible with high-temperature liquid lithium lead (LiPb) and molten salt media. It solves the problem that existing platforms cannot handle LiPb media and its intermittent operation characteristics, and realizes high-fidelity simulation of the working environment of fusion reactor thermal storage heat exchangers.

[0017] 2. This invention proposes a thermal performance testing process based on periodic start-stop control (running time t1 + stopping time t2), and judges whether the system has reached "intermittent steady state" by comparing data from multiple cycles, thereby scientifically obtaining key performance parameters such as heat transfer coefficient and resistance drop, filling the gap in the method of performance evaluation of non-continuous heat exchange equipment.

[0018] 3. This invention effectively isolates oxygen / water vapor by setting up an argon protection branch, preventing high-temperature lithium and lead oxidation; at the same time, a bypass mixing branch is introduced into the molten salt circuit to regulate the inlet temperature of the air cooler by mixing hot and cold molten salt, avoiding damage to the equipment due to instantaneous high-temperature impact and significantly extending the service life of the system.

[0019] 4. This invention integrates multi-point temperature, pressure, and flow sensors with a PLC controller to achieve real-time acquisition and closed-loop control of all parameters on the hot side (LiPb) and cold side (molten salt), ensuring the accuracy of test data and the repeatability of the experimental process, and providing a reliable basis for the design optimization and operation strategy formulation of fusion reactor thermal storage heat exchangers. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of a thermal performance testing system for an intermittently operating heat exchanger of a fusion device according to the present invention.

[0021] The attached diagram is labeled as follows: 1-Lithium-lead filling and circulation loop, 11-Heat exchanger under test, 12-First pump, 13-First valve, 14-Electric heater, 15-Expansion tank, 16-Second valve, 17-Lithium-lead storage tank, 18-Third valve, 19-Second pump, 110-Fourth valve, 111-Lithium-lead storage tank heater, 2-Argon protection branch, 21-High-pressure argon cylinder, 22-Fifth valve, 23-Sixth valve, 24-Seventh valve, 25-Eighth valve, 3-Molten salt circulation loop, 31-Molten salt storage tank, 32-Ninth valve, 33-Third pump, 34-Tenth valve, 35-Eleventh valve, 3 6-Air cooler, 37-Molten salt storage tank heater, 41-First thermocouple, 42-Second thermocouple, 43-Third thermocouple, 44-Fourth thermocouple, 45-Fifth thermocouple, 46-Sixth thermocouple, 47-Seventh thermocouple, 48-Eighth thermocouple, 49-Ninth thermocouple, 410-First flow meter, 411-Second flow meter, 412-First pressure sensor, 413-Second pressure sensor, 414-Third pressure sensor, 415-Fourth pressure sensor, 416-Fifth pressure sensor, 417-Sixth pressure sensor, 418-Seventh pressure sensor, 419-PLC controller. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0023] like Figure 1 As shown, the thermal performance testing system for an intermittently operating heat exchanger of a fusion device according to the present invention includes a lithium-lead filling and circulation loop 1, an argon protection branch 2, a molten salt circulation loop 3, and a measurement and control system. The lithium-lead filling and circulation loop 1 is connected to the hot side of the heat exchanger 11 under test, and the molten salt circulation loop 3 is connected to the cold side of the heat exchanger 11 under test. There is no connection between the lithium-lead filling and circulation loop 1 and the molten salt circulation loop 3. The argon protection branch 2 is connected to the gas phase space of the expansion tank 15 and the lithium-lead storage tank 17 in the lithium-lead filling and circulation loop 1 to protect the lithium-lead medium. The measurement and control system tests the temperature, flow rate, and pressure in the lithium-lead filling and circulation loop 1 and the molten salt circulation loop 3, and controls the start-up, shutdown, and flow rate adjustment of the lithium-lead filling and circulation loop 1 and the molten salt circulation loop 3.

[0024] The lithium-lead filling and circulation loop 1 can be divided into a lithium-lead filling loop and a lithium-lead circulation loop. The lithium-lead circulation loop includes a first pump 12, a first valve 13, an electric heater 14, an expansion tank 15, a second valve 16, and the hot side of the heat exchanger under test 11. The lithium-lead filling loop includes a lithium-lead storage tank 17, a third valve 18, a second pump 19, and a fourth valve 110, which realizes the filling and discharge of lithium-lead. During the experimental testing phase, this part is in a closed state.

[0025] Overall, the lithium-lead filling and circulation loop 1 includes a heat exchanger under test 11, a first pump 12, a first valve 13, an electric heater 14, an expansion tank 15, a second valve 16, a lithium-lead storage tank 17, a third valve 18, a second pump 19, a fourth valve 110, a lithium-lead storage tank heater 111, and connecting pipelines. The hot-side outlet of the heat exchanger under test 11 is connected to the inlet of the first pump 12, the outlet of the first pump 12 is connected to the inlet of the first valve 13, the outlet of the first valve 13 is connected to the inlet of the electric heater 14, the outlet of the electric heater 14 is connected to the inlet of the second valve 16, the liquid phase inlet of the expansion tank 15 is connected to the pipeline between the electric heater 14 and the second valve 16, and the outlet of the second valve 16 is connected to the inlet of the heat exchanger under test 11. The liquid phase outlet of the lithium-lead storage tank 17 is connected to the inlet of the third valve 18. The outlet of the third valve 18 is connected to the inlet of the second pump 19. The outlet of the second pump 19 is connected to the pipeline between the electric heater 14 and the second valve 16. The lowest point of the lithium-lead circulation loop pipeline is connected to the inlet of the fourth valve 110. The outlet of the fourth valve 110 is connected to the liquid phase inlet of the lithium-lead storage tank 17. The lithium-lead storage tank heater 111 is located at the top of the lithium-lead storage tank 17 and extends into the interior of the lithium-lead storage tank 17.

[0026] The argon protection branch 2 includes a high-pressure argon cylinder 21, a fifth valve 22, a sixth valve 23, a seventh valve 24, an eighth valve 25, and connecting pipelines. The outlet of the high-pressure argon cylinder 21 is connected to the inlet of the fifth valve 22, and the outlet of the fifth valve 22 is connected to the inlet of the sixth valve 23. The outlet of the sixth valve 23 is divided into two branches: the first branch is connected to the inlet of the seventh valve 24, and the outlet of the seventh valve 24 is connected to the gas phase inlet of the lithium-lead storage tank 17; the second branch is connected to the inlet of the eighth valve 25, and the outlet of the eighth valve 25 is connected to the gas phase inlet of the expansion tank 15.

[0027] The molten salt circulation loop 3 includes a molten salt storage tank 31, a ninth valve 32, a third pump 33, a tenth valve 34, an eleventh valve 35, an air cooler 36, a molten salt storage tank heater 37, and connecting pipelines. The outlet of the molten salt storage tank 31 is connected to the inlet of the ninth valve 32, and the outlet of the ninth valve 32 is connected to the inlet of the third pump 33. The outlet of the third pump 33 is divided into two branches. The first branch is connected to the inlet of the cold side of the heat exchanger 11 under test, and the second branch is connected to the inlet of the tenth valve 34. The outlet of the cold side of the heat exchanger 11 under test merges with the outlet of the tenth valve 34 and then connects to the inlet of the eleventh valve 35. The outlet of the eleventh valve 35 is connected to the inlet of the air cooler 36, and the outlet of the air cooler 36 is connected to the inlet of the molten salt storage tank 31.

[0028] The measurement and control system includes a first thermocouple 41, a second thermocouple 42, a third thermocouple 43, a fourth thermocouple 44, a fifth thermocouple 45, a sixth thermocouple 46, a seventh thermocouple 47, an eighth thermocouple 48, a ninth thermocouple 49, a first flow meter 410, a second flow meter 411, a first pressure sensor 412, a second pressure sensor 413, a third pressure sensor 414, a fourth pressure sensor 415, a fifth pressure sensor 416, a sixth pressure sensor 417, a seventh pressure sensor 418, and a PLC controller 419.

[0029] The first thermocouple 41 is installed at the outlet of the electric heater 14 to measure the temperature of the medium at the outlet of the electric heater 14; the second thermocouple 42 is installed at the hot-side inlet of the heat exchanger 11 under test to measure the temperature of the hot-side inlet of the heat exchanger 11 under test; the third thermocouple 43 is installed at the hot-side outlet of the heat exchanger 11 under test to measure the temperature of the hot-side outlet of the heat exchanger 11 under test; the fourth thermocouple 44 is installed inside the molten salt storage tank 31 to measure the temperature of the medium inside the molten salt storage tank 31; the fifth thermocouple 45 is installed at the cold-side inlet of the heat exchanger 11 under test to measure the temperature of the cold-side inlet of the heat exchanger 11 under test; and the sixth thermocouple 46 is installed... A seventh thermocouple 47 is installed at the cold-side outlet of the heat exchanger 11 under test, used to measure the temperature of the cold-side outlet of the heat exchanger 11 under test; an eighth thermocouple 48 is installed at the outlet of the air cooler 36, used to measure the temperature of the outlet of the air cooler 36; a ninth thermocouple 49 is installed inside the lithium-lead storage tank 17, used to measure the temperature of the medium inside the lithium-lead storage tank 17; a first flow meter 410 is installed on the outlet pipe of the first pump 12 in the lithium-lead circulation loop, used to measure the flow rate of the hot-side medium of the heat exchanger 11 under test; a second flow meter 411 is installed on the cold-side inlet pipe of the heat exchanger 11 under test. The heat exchanger 11 under test is equipped with four pressure sensors: a first pressure sensor 412 located at the hot-side inlet of the heat exchanger 11 and used to measure the inlet pressure of the hot-side medium; a second pressure sensor 413 located at the cold-side inlet of the heat exchanger 11 and used to measure the inlet pressure of the cold-side medium; a third pressure sensor 414 located at the hot-side outlet of the heat exchanger 11 and used to measure the outlet pressure of the hot-side medium; and a fourth pressure sensor 415 located at the cold-side outlet of the heat exchanger 11 and used to measure the outlet pressure of the cold-side medium. The pressure sensor 416 is located at the outlet of the sixth valve 23 on the outlet pipeline of the high-pressure argon cylinder 21 and is used to measure the pressure of the high-pressure argon cylinder 21 supplying gas to the branch; the sixth pressure sensor 417 is located inside the expansion tank 15 and is used to measure the internal pressure of the expansion tank 15; the seventh pressure sensor 418 is located inside the lithium-lead storage tank 17 and is used to measure the internal pressure of the lithium-lead storage tank 17; the PLC controller 419 is used to control the start-up, shutdown and adjustment of the first pump 12, the first valve 13, the electric heater 14, the second valve 16, the ninth valve 32, the third pump 33, the tenth valve 34, the eleventh valve 35 and the air cooler 36.

[0030] Preferably, all lithium-lead and molten salt pipelines are externally equipped with pipe electric heating to heat the pipelines and prevent lithium-lead and molten salt from solidifying.

[0031] Based on the above-mentioned intermittent operation heat exchanger thermal performance testing system for fusion devices, this invention also provides a method for testing the thermal performance of intermittent operation heat exchangers for fusion devices, including:

[0032] 1. Before the heat exchanger thermal performance test begins, all valves and pumps are closed. Turn on the lithium-lead storage tank heater 111, the molten salt storage tank heater 37, and the pipeline electric heat tracing to preheat the lithium-lead storage tank 17, the molten salt storage tank 31, and the pipeline, respectively. When the internal medium temperature T9 of the lithium-lead storage tank 17 reaches the set temperature T90, open the third valve 18, the second valve 16, and the first valve 13, and simultaneously start the second pump 19. When the lithium-lead circulation loop is full of medium and the internal system pressure stabilizes at the set pressure, close the third valve 18 and the second pump 19. The upper space of the expansion tank 15 and the lithium-lead storage tank 17 is connected to the high-pressure argon cylinder 21 through valves to maintain the argon protection of the medium inside the tank. When the internal medium temperature T4 of the molten salt storage tank heater 37 reaches the set temperature T40, open the ninth valve 32, the tenth valve 34, the eleventh valve 35, and the third pump 33. After the molten salt circulation loop 3 is full of medium, close the ninth valve 32, the tenth valve 34, the eleventh valve 35, and the third pump 33.

[0033] 2. Conduct thermal performance tests on intermittently operating heat exchangers, including:

[0034] For the lithium-lead circulation loop: Open the first valve 13, the second valve 16, and the first pump 12. Adjust the opening of the first valve 13 through the PLC controller 419 to make the medium flow rate M1 in the lithium-lead circulation loop reach the set value m1. At the same time, turn on the electric heater 14 and operate at the target power PW. The flow mode of the medium in the lithium-lead circulation loop is as follows: The lithium-lead medium flows out from the hot side outlet of the heat exchanger 11 under test, flows through the first pump 12 and the first valve 13 in sequence, and flows into the electric heater 14. After being heated, the outlet temperature T1 of the electric heater 14 reaches the set temperature T10. Due to the temperature rise, the lithium-lead medium inside the system expands to the expansion tank 15 to maintain a constant pressure in the system. The lithium-lead medium continues to flow through the second valve 16 and flows into the hot side inlet of the heat exchanger 11 under test. After exchanging heat with the cold side molten salt in the heat exchanger 11 under test, the temperature decreases and flows out from the hot side outlet of the heat exchanger 11 under test.

[0035] For molten salt circulation loop 3: Open the ninth valve 32 and the eleventh valve 35, and simultaneously start the third pump 33 and the air cooler 36; adjust the opening of the ninth valve 32 through the PLC controller 419 to make the medium flow rate M2 in molten salt circulation loop 3 reach the set value m2; control the air flow rate of the air cooler 36 through the PLC controller 419 to maintain the molten salt outlet temperature T8 of the air cooler 36 at the set value T80. The flow mode of the medium in molten salt circulation loop 3 is as follows: molten salt flows out from the outlet of molten salt storage tank 31, flows through the ninth valve 32 and the third pump 33 in sequence, flows into the cold side inlet of the heat exchanger 11 under test, exchanges heat with the hot side medium of the heat exchanger 11 under test, and after the temperature rises, flows out from the cold side outlet of the heat exchanger 11 under test, flows through the eleventh valve 35, flows into the air cooler 36, is cooled by air, and then flows into the molten salt storage tank 31. When the inlet temperature T7 of the air cooler 36 is too high under test conditions, in order to prevent the inlet and outlet temperature difference of the air cooler 36 from being too large, the opening of the ninth valve 32 and the power of the third pump 33 are adjusted by the PLC controller 419. At the same time, the tenth valve 34 is opened and its opening is controlled. The medium flow rate M2 is kept at the set value m2. Some of the unheated molten salt medium flows directly through the tenth valve 34 and mixes with the molten salt at the cold side outlet of the heat exchanger 11 under test, thereby reducing the inlet temperature T7 of the air cooler 36. Then it enters the air cooler 36 for cooling and then flows into the molten salt storage tank 31.

[0036] The lithium-lead circulation loop and molten salt circulation loop 3 are controlled by PLC controller 419 to run continuously for time t1, and paused for time t2. One test cycle time is t = t1 + t2, where t1 represents the running time and t2 represents the pause time. The test is carried out continuously for no less than 3 test cycles according to the above running and pause times.

[0037] Using the test cycle time t as the unit, the hot-side flow rate M1, hot-side medium inlet pressure P1, hot-side medium outlet pressure P3, hot-side medium inlet temperature T2, and hot-side medium outlet temperature T3 of the tested heat exchanger 11 are tested and recorded in each cycle. The cold-side flow rate M2, cold-side medium inlet pressure P2, cold-side medium outlet pressure P4, cold-side medium inlet temperature T5, and cold-side medium outlet temperature T6 of the tested heat exchanger 11 are also tested. By comparing the hot-side medium inlet temperature T2, hot-side medium outlet temperature T3, cold-side medium inlet temperature T5, and cold-side medium outlet temperature T6 in each cycle, if the temperature change value between the first and last two cycles (such as the nth cycle and the (n+1th cycle) does not exceed 5%, the state of the heat exchanger is considered to have reached stability. The heat exchanger performance was evaluated using temperature, flow rate, and pressure data from the stabilized test period (the (n+1)th period). First, the average hot-side flow rate was calculated based on the following parameters within the operating time t1: hot-side flow rate M1, hot-side medium inlet pressure P1, hot-side medium outlet pressure P3, hot-side medium inlet temperature T2, hot-side medium outlet temperature T3, cold-side flow rate M2, cold-side medium inlet pressure P2, cold-side medium outlet pressure P4, cold-side medium inlet temperature T5, and cold-side medium outlet temperature T6. Average inlet pressure of hot side medium Average outlet pressure of hot side medium Average temperature of the hot-side medium inlet Average temperature of hot-side medium outlet Average flow rate on the cold side Average inlet pressure of cold side medium Average outlet pressure of cold side medium Average temperature of cold side medium inlet Average temperature of cold side medium outlet .

[0038] Calculate the heat exchanger hot-side resistance drop :

[0039] ;

[0040] Calculate the cold-side resistance drop of the heat exchanger :

[0041] ;

[0042] Calculate the average resistance drop on both sides of the heat exchanger :

[0043] ;

[0044] Calculate the average temperature difference of heat exchanger :

[0045] ;

[0046] Calculate the overall heat transfer coefficient of the heat exchanger :

[0047] ;

[0048] In the formula, The average specific heat capacity of the hot-side medium. This represents the heat exchange area of ​​the heat exchanger.

[0049] The average resistance drop obtained from the calculation and overall heat transfer coefficient Evaluate the thermal performance of heat exchangers operating intermittently.

[0050] Figure 1 In the diagram, P5, P6, and P7 represent the pressure values ​​of the fifth pressure sensor 416, the sixth pressure sensor 417, and the seventh pressure sensor 418, respectively.

[0051] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A system for testing the thermal performance of an intermittent operation heat exchanger of a fusion device, characterized in that, The system includes a lithium-lead filling and circulation loop for providing the hot-side circulating medium, an argon protection branch for maintaining an inert atmosphere, a molten salt circulation loop for providing the cold-side circulating medium, and a measurement and control system for acquiring data and controlling operation. The lithium-lead filling and circulation loop includes a heat exchanger under test, whose hot-side outlet is sequentially connected to a first pump for driving the lithium-lead flow, a first valve, an electric heater for heating the lithium-lead, and a second valve. The outlet of the second valve is connected to the hot-side inlet of the heat exchanger under test. An expansion tank is connected to the pipeline between the electric heater and the second valve to accommodate volume expansion. The lithium-lead storage tank is connected to a third valve and a replenishment system. The second pump is connected to the pipeline, and the fourth valve connects the lowest point of the lithium-lead circulation loop to the lithium-lead storage tank to achieve venting. The argon protection branch includes a high-pressure argon cylinder, which is divided into two paths after passing through the fifth and sixth valves, supplying gas to the gas phase space of the lithium-lead storage tank and the expansion tank through the seventh and eighth valves, respectively. The molten salt circulation loop includes a molten salt storage tank, whose outlet is divided into two paths after passing through the ninth valve and the third pump used to drive the molten salt. One path is connected to the cold side inlet of the heat exchanger under test, and the other path forms a bypass mixing branch through the tenth valve. The cold side outlet of the heat exchanger under test merges with the bypass mixing branch and returns to the molten salt storage tank through the air cooler used for cooling.

2. The thermal performance testing system for intermittent operation heat exchangers of a fusion device according to claim 1, characterized in that, After the molten salt merges with the bypass mixing branch at the cold side outlet of the heat exchanger under test, it is sent into the air cooler after passing through the eleventh valve.

3. The thermal performance testing system for an intermittently operating heat exchanger of a fusion device according to claim 1, characterized in that, The outer walls of the pipes in the lithium-lead filling and circulation loop and the molten salt circulation loop are equipped with electric heating devices to maintain the temperature of the medium during transportation.

4. The thermal performance testing system for an intermittently operating heat exchanger of a fusion device according to claim 2, characterized in that, The measurement and control system includes thermocouples, flow meters, and pressure sensors installed on the hot and cold sides of the heat exchanger under test, the outlet of the electric heater, the molten salt storage tank, the lithium-lead storage tank, the inlet and outlet of the air cooler, the outlet of the first pump, and the expansion tank.

5. The thermal performance testing system for an intermittently operating heat exchanger of a fusion device according to claim 4, characterized in that, The measurement and control system also includes a PLC controller for controlling the start-up and shutdown of the first pump, the first valve, the electric heater, the second valve, the ninth valve, the third pump, the tenth valve, the eleventh valve, and the air cooler, as well as adjusting their operating parameters.

6. A method for testing the thermal performance of a heat exchanger during intermittent operation of a fusion device, based on the thermal performance testing system for an intermittently operating heat exchanger of a fusion device as described in any one of claims 1 to 5, characterized in that, Includes the following steps: Preheating lithium-lead storage tanks, molten salt storage tanks and pipelines; Fill the lithium-lead filling and circulation loops and the molten salt circulation loops with the medium and establish the initial pressure; Open the lithium-lead circulation loop and the molten salt circulation loop, adjust the hot side flow rate to the set value and start the electric heater to make the hot side medium reach the set temperature. At the same time, adjust the cold side flow rate to the set value and control the air cooler to maintain its outlet temperature constant. The lithium-lead circulation loop and the molten salt circulation loop are controlled to run continuously during the running time t1 and paused during the stopping time t2, which constitutes a test cycle time t = t1 + t2; t1 is the running time and t2 is the pause time; the test cycle time is repeated for no less than three test cycles. The average resistance drop, average temperature difference, and overall heat transfer coefficient on the hot and cold sides of the lithium-lead and molten salt circulation loops are calculated to evaluate the thermal performance of the heat exchangers under test.

7. The method for testing the thermal performance of a heat exchanger during intermittent operation of a fusion device according to claim 6, characterized in that, During the operation of the molten salt circulation loop, when the inlet temperature of the air cooler exceeds the set limit, the tenth valve is opened and its opening degree is adjusted to mix some of the unheated molten salt with the molten salt at the cold side outlet of the heat exchanger under test, so as to reduce the temperature of the molten salt entering the air cooler.

8. The method for testing the thermal performance of a heat exchanger during intermittent operation of a fusion device according to claim 6, characterized in that, During each test cycle, data on the flow rate, inlet and outlet pressure, and inlet and outlet temperature of the heat exchanger under test on the hot and cold sides are collected.

9. A method for testing the thermal performance of a heat exchanger during intermittent operation of a fusion device according to claim 6, characterized in that, By comparing the inlet and outlet temperature data of the hot and cold sides of the heat exchanger under test in two consecutive test cycles, it is determined that the intermittent steady state has been reached when the temperature change between adjacent cycles does not exceed 5%.

10. A method for testing the thermal performance of a heat exchanger during intermittent operation of a fusion device according to claim 9, characterized in that, Data used to evaluate the thermal performance of the heat exchanger under test is selected from data collected during the test cycle after the intermittent steady state has been reached.

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