Thermal cycling testing device and thermal cycling testing method for heat storage material

Abstract

The invention discloses a thermal cycling testing device and a thermal cycling testing method for a heat storage material, in the structure of the thermal cycling testing device, a liquid heat transfer medium is accommodated in a high-temperature tank and is used for immersing a test tube; one end of the temperature detection device extends into a sample to be detected in the test tube, and the transmission device drives the test tube and the temperature detection device to move between the high-low temperature tank and extends into or is far away from the high-low temperature tank; and the air cooling mechanism sucks air flow or blows air to take away heat released by the test tubes in the low-temperature tank. The thermal cycling test device and the thermal cycling test method for the heat storage material can truly simulate the actual use working condition of the heat storage material, and more accurately evaluate the service life performance of a sample in the actual working condition; the two separated independent chambers are used for heating and cooling a static sample respectively, so that the testing efficiency and the temperature control accuracy are improved; and a plurality of test tubes are used for testing at the same time and circularly move in the high-temperature tank and the low-temperature tank, so that the testing efficiency is further improved.

Description

Technical Field

[0001] The present invention relates to the technical field of material testing, and in particular to a device and method for testing the thermal cycle of a heat storage material. Background Art

[0002] Under the background of "dual carbon", my country vigorously promotes the reform of clean energy structure, and the installed capacity of new energy is growing rapidly. With the urgent need for large-capacity and large-scale heat storage and peak regulation in solar thermal power generation, thermal power peak regulation and multi-energy complementary integrated energy systems, the Ministry of Science and Technology pointed out in the National Key R&D Program to study "mixed molten salt materials with low melting point, high decomposition temperature, low cost and low corrosion", and Jiangsu Province's "Guidelines for Special Fund Projects for Provincial Carbon Peaking and Carbon Neutrality Science and Technology Innovation in 2024" pointed out that "in response to the demand for safe, efficient, low-cost and long-term energy storage for source, grid and load storage, research low melting point, wide temperature range, high temperature and large capacity molten salt heat storage", and the "Shanghai New Energy Storage Demonstration Leading Innovation Development Work Plan (2025-2030)" issued by the Shanghai Municipal People's Government pointed out that "regarding thermal energy storage, tackle sensible heat storage technology, and develop high-temperature molten salt materials with wide temperature range, low melting point, high specific heat and low corrosion".

[0003] As an important heat transfer and heat storage medium, the stability and reliability of molten salt performance have attracted much attention. In engineering projects, molten salt will undergo multiple hot and cold cycles, which may affect its physical and chemical properties. The engineering application requires the new molten salt material to have a stable charging and discharging cycle performance of more than 10,000 times (calculated as one cycle per day for 30 years). The charging and discharging cycle life test of the new molten salt material has become an important factor restricting the engineering application of the new molten salt material. Therefore, a test device that can accurately simulate the hot and cold cycle process of molten salt under actual working conditions is needed.

[0004] my country's scientific research institutions and related enterprises have studied the test methods for the cycle life of molten salt and heat storage materials, but the existing test devices have problems such as low test efficiency, low temperature control accuracy, and inability to simulate actual working conditions. For example, differential scanning calorimetry (DSC) can determine the changes in the properties of heat storage materials by testing the heating and cooling curves of heat storage materials. This method can only test one mg-level sample each time, and the cycle test speed is slow. Engineering applications often use tons to 10,000 tons of molten salt, and this test method has little significance for engineering guidance. In the master's thesis "Research on the Dispersion Uniformity and Stability of Nano-nitrate" and "Preparation and Performance Research of Medium and High Temperature Steady Composite Phase Change Heat Storage Materials", a molten salt or heat storage material cycle test platform was built. The high temperature zone is a thermoelectric furnace, and the low temperature zone is air-cooled. The sample is tested for the number of cycles of the high and low temperature zone reciprocating motion experiment. However, due to the low heat transfer efficiency of air, the temperature of the thermoelectric furnace needs to be much higher than the sample temperature to cycle quickly, which makes the sample easy to overheat, resulting in sample decomposition or volatilization, resulting in a large deviation between the experimental results and the engineering application. For example, the utility model patent "A material hot and cold cycle test device" (CN204128918U) discloses a rapid charging and discharging cycle test platform for heat storage materials. The high-temperature chamber is an air (or atmosphere) heating furnace. Since the thermal conductivity of air is low, in order to quickly realize charging and discharging, the furnace temperature needs to be much higher than the sample temperature to realize rapid charging and discharging cycle. However, this makes the sample prone to overheating, and the experimental results cannot provide a reference for engineering applications. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the defects in the prior art that the hot and cold cycle devices for testing heat storage materials such as molten salt cannot simulate actual working conditions, have low testing efficiency and poor temperature control accuracy, and to provide a hot and cold cycle testing device and a hot and cold cycle testing method for heat storage materials.

[0006] The present invention solves the above technical problems through the following technical solutions:

[0007] A hot and cold cycle test device for heat storage materials, the hot and cold cycle test device comprising a heating system, a high temperature tank, a low temperature tank, a plurality of temperature detection devices and an air cooling mechanism, the hot and cold cycle test device also comprising a plurality of test tubes containing samples to be tested and a transmission device, the samples to be tested being heat storage materials; the high temperature tank contains a liquid heat transfer medium, the heating system is used to heat the liquid heat transfer medium, during testing, the samples to be tested in the test tube are completely immersed in the liquid heat transfer medium; one end of the temperature detection device extends into the sample to be tested in the test tube, the other end of the temperature detection device and the test tube are both mounted on the transmission device, the transmission device drives the test tube and the temperature detection device to move back and forth between the high temperature tank and the low temperature tank, and during testing, the sample to be tested is placed in the high temperature tank or the low temperature tank; the air cooling mechanism is used to take away the heat in the low temperature tank, so as to ensure that the temperature of the low temperature tank is reduced to or below the set lower limit of the test temperature during testing.

[0008] In this scheme, the hot and cold cycle test device of the heat storage material heats the liquid heat transfer medium in the high-temperature tank through the heating system, and the liquid heat transfer medium transfers the heat to the test tube immersed therein, thereby transferring the heat to the heat storage material in the test tube, realizing the heat transfer of the liquid heat transfer medium to the heat storage material; compared with air heat transfer, the liquid heat transfer medium is used to uniformly contact the outer surface of the test tube, the heat transfer efficiency is higher, and it is heated faster. There is no need to heat the liquid heat transfer medium to a very high temperature, and the heat can be effectively transferred to the heat storage material to protect the sample from overheating. It can truly simulate the actual use conditions of the heat storage material and more accurately evaluate the service life performance of the sample to be tested under actual conditions; and the liquid heat transfer medium is used for heat transfer, and the heat transfer is uniform, which is conducive to improving the accuracy of temperature measurement and reducing measurement data errors. The static sample to be tested is heated and cooled respectively by two separate independent chambers, the high temperature tank and the low temperature tank, without affecting each other, which is conducive to improving the test efficiency of hot and cold cycles and the accuracy of temperature control; on this basis, multiple test tubes are tested simultaneously and circulated in the high temperature tank and the low temperature tank through the transmission device, which further improves the test efficiency. By extending one end of the temperature detection device into the static sample to be tested, it is in direct contact with the sample to be tested and is not affected by the fluidity of the sample to be tested, thereby improving the accuracy of temperature control. The heat in the low temperature tank is taken away by the air cooling mechanism so that it does not exceed the set lower limit of the test temperature, thereby improving the cooling speed during low temperature testing.

[0009] Preferably, the heating system is wrapped around the outer walls of the high-temperature tank, and / or the outer sides of the heating system and the high-temperature tank are also wrapped with a thermal insulation layer.

[0010] In this solution, the heating system is wrapped around the outer wall of the high-temperature tank, which is convenient for maintenance, and is also conducive to heating uniformity, temperature control accuracy, and improved heating efficiency. By wrapping the insulation layer on the outside of the heating system and the high-temperature tank, heat loss is reduced, which is conducive to shortening the heating process and improving test efficiency.

[0011] Preferably, the high temperature tank is a cylindrical structure or at least the bottom of the high temperature tank is a hemispherical structure.

[0012] In this solution, the high-temperature tank adopts a cylindrical structure or its bottom adopts a hemispherical structure, which increases the contact area of ​​the liquid heat transfer medium, avoids the appearance of cold areas in the high-temperature tank, and makes the temperature field of the liquid heat transfer medium more uniform, which is beneficial to the accuracy of temperature control and improves heating efficiency.

[0013] Preferably, the maximum temperature at which the selected liquid heat transfer medium is heated is not lower than the set upper limit of the test temperature of the sample to be tested.

[0014] In this scheme, a suitable liquid heat transfer medium is selected according to the upper limit of the test temperature required for the cycle life test of the sample to be tested, ensuring that its maximum temperature after heating is not lower than the upper limit of the test temperature and that there is sufficient heating temperature space to meet the requirements of the cycle high temperature test.

[0015] Preferably, the hot and cold cycle testing device further comprises a stirring device, wherein the stirring device comprises a stirring member, at least a portion of which extends into the liquid heat transfer medium in the high temperature tank for stirring the liquid heat transfer medium.

[0016] In this solution, the stirring member is extended into the liquid heat transfer medium to stir it, which is beneficial to the temperature uniformity of the liquid heat transfer medium at different positions in the high-temperature tank, and is beneficial to improving the accuracy of temperature measurement and reducing measurement data errors.

[0017] Preferably, the stirring device also includes a driving mechanism and a stirring mechanism, the driving mechanism is arranged at a position away from the high-temperature tank, the stirring mechanism includes an eccentric wheel, a connecting rod and the stirring member, the output shaft of the driving mechanism is connected to the eccentric wheel, and the two ends of the connecting rod are respectively connected to the eccentric wheel and the stirring member.

[0018] In this solution, the stirring device forms a reciprocating eccentric connecting rod stirring structure through the above-mentioned structural arrangement, wherein the driving mechanism drives the eccentric wheel to realize eccentric reciprocating motion, thereby driving the stirring member to realize eccentric reciprocating motion through the connecting rod, so that the stirring member realizes the stirring function. The driving mechanism is arranged at a position away from the high-temperature tank to prevent the high temperature in the high-temperature tank from being transmitted to the driving mechanism and damaging the driving mechanism.

[0019] Preferably, a partition is provided between the driving mechanism and the stirring mechanism.

[0020] In this embodiment, a partition is provided between the driving mechanism and the stirring mechanism to further insulate the driving mechanism.

[0021] Preferably, the air cooling mechanism includes a fan and an air duct, the low-temperature tank is provided with an air outlet, the air intake of the fan is arranged opposite to the air outlet of the low-temperature tank; the fan is connected to the air duct, the air duct is connected to the external environment, and the fan is used to draw the airflow in the low-temperature tank.

[0022] In this solution, the fan of the air cooling mechanism takes away the heat released by the heated test tube in the low temperature tank by suction, thereby cooling the sample to be tested in the test tube. In addition, the cooling is achieved by suction, the airflow is stable, and the heat is taken out of the low temperature tank more quickly.

[0023] Preferably, the transmission device includes a horizontal transmission device and a vertical transmission device, the vertical transmission device is slidably connected to the horizontal transmission device in a horizontal direction, the test tube and the temperature detection device are installed on the vertical transmission device, and the vertical transmission device is used to drive the test tube and the temperature detection device to move vertically and move together on the horizontal transmission device.

[0024] In this solution, the transmission device realizes rapid movement between the high-temperature tank and the low-temperature tank through the transmission device in two different directions, horizontally and vertically.

[0025] Preferably, the temperature detection device extends into one end of the sample to be tested and is spaced apart from the inner wall of the test tube; and / or the liquid heat transfer medium is liquid molten salt.

[0026] In this solution, the end of the temperature detection device that extends into the sample to be tested is spaced from the inner wall of the test tube to form a suspended state, so that the temperature measurement point truly reflects the temperature of the sample to be tested, and is not affected by the temperature of the test tube and outside the test tube, thereby improving the accuracy of temperature detection. The liquid heat transfer medium uses liquid molten salt, which uses the good thermal conductivity of molten salt. On the one hand, it is beneficial to improve the heating efficiency. On the other hand, it does not need to heat the liquid molten salt to a very high temperature to effectively transfer heat to the sample to be tested, ensuring that the sample will not overheat. It can truly simulate the actual use conditions of the heat storage material and more accurately evaluate the service life performance of the sample to be tested in actual working conditions.

[0027] A method for testing a thermal storage material by cold and hot cycles, the method using a thermal storage material cold and hot cycle testing device as described above to perform a cold and hot cycle test, the method comprising the following steps:

[0028] S1, starting the heating system;

[0029] S2, enter the hot and cold cycle test mode, each hot and cold cycle test includes the following steps:

[0030] heating the liquid heat transfer medium in the high temperature tank;

[0031] Immersing a plurality of the test tubes simultaneously or successively in the liquid heat transfer medium in the high-temperature tank, and heating the samples to be tested in the test tubes;

[0032] Using the temperature detection device to detect the temperature of the sample to be tested;

[0033] Determine whether the state of the sample to be tested in the high-temperature tank satisfies a set first control point, wherein the first control point is whether the temperature of the sample to be tested reaches a set test temperature upper limit and / or whether the residence time of the sample to be tested in the high-temperature tank reaches a set first interval time;

[0034] If the conditions are met, the test tube and the temperature detection device are lifted by the transmission device and moved into the low-temperature tank;

[0035] Using the air cooling mechanism to act on the low temperature tank to take away the heat in the low temperature tank, so as to ensure that the temperature of the low temperature tank is reduced to or below the set lower limit of the test temperature during the test;

[0036] Determine whether the state of the sample to be tested in the low temperature tank meets a set second control point, wherein the second control point is whether the temperature of the sample to be tested reaches a set lower limit of the test temperature and / or whether the residence time of the sample to be tested in the low temperature tank reaches a set second interval time;

[0037] S3, if the state of the sample to be tested in the low temperature tank meets the set second control point, repeat the step S2 and calculate the number of cycles;

[0038] S4, determining whether the number of cycles reaches a set number;

[0039] S5. If the set number of times is reached, the test is stopped and the heating system is turned off.

[0040] In this scheme, the hot and cold cycle test method of the heat storage material can truly simulate the actual use conditions of the heat storage material through the above steps, and more accurately evaluate the service life performance of the sample to be tested under actual conditions; and improve the test efficiency and the accuracy of temperature control. If multiple test tubes are immersed in a liquid heat transfer medium for heating at the same time, the amount of samples to be tested is increased, thereby improving the test efficiency; if multiple test tubes are loaded with different samples to be tested, and the multiple test tubes are immersed in a liquid heat transfer medium for heating one after another, the life performance of different samples to be tested can be compared. The first control point and the second control point respectively implement two different logic controls in the form of temperature control (test temperature upper limit or test temperature lower limit) and residence time to meet different performance evaluation requirements of the cycle test.

[0041] Preferably, in step S2, the first control point is whether the temperature of the sample to be tested reaches the set test temperature upper limit, and the step of "determining whether the state of the sample to be tested in the high-temperature tank meets the set first control point" specifically includes: determining whether the temperature of the sample to be tested with the lowest temperature is not lower than the set test temperature upper limit; and / or,

[0042] In step S2, the second control point is the set lower limit of the test temperature of the sample to be tested, and the step of "determining whether the state of the sample to be tested in the low-temperature tank meets the set second control point" specifically includes: determining whether the temperature of the sample to be tested with the highest temperature is not higher than the set lower limit of the test temperature.

[0043] In this solution, when the first control point is whether the temperature of the sample to be tested reaches the set upper limit of the test temperature, it is judged whether the temperature of the sample to be tested with the lowest temperature is not lower than the set upper limit of the test temperature of the sample to be tested. With such a judgment condition, it is ensured that the sample to be tested with the lowest temperature is also completely heated to the upper limit of the test temperature, and the life performance of all the samples to be tested can be accurately evaluated. When the second control point is whether the temperature of the sample to be tested reaches the set lower limit of the test temperature, it is judged whether the temperature of the sample to be tested with the highest temperature is not higher than the set lower limit of the test temperature of the sample to be tested. With such a judgment condition, it is ensured that the sample to be tested with the highest temperature is also completely cooled to the lower limit of the test temperature, and the life performance of all the samples to be tested can be accurately evaluated.

[0044] Preferably, the hot and cold cycle testing device further comprises a stirring device, and the stirring device comprises a stirring member, and the step S2 further comprises the following steps: using the stirring member to extend into the liquid heat transfer medium in the high temperature tank to stir the liquid heat transfer medium.

[0045] In this solution, the stirring member is extended into the liquid heat transfer medium to stir it, which is beneficial to the temperature uniformity of the liquid heat transfer medium at different positions in the high-temperature tank, and is beneficial to improving the accuracy of temperature measurement and reducing measurement data errors.

[0046] Preferably, in step S2, the first interval time is not less than the time it takes for the sample to be tested to be heated from a set low temperature by the liquid heat transfer medium to a set upper limit of the test temperature;

[0047] And / or, the second interval time is not less than the time it takes for the sample to be tested to be cooled from a set high temperature to a set lower limit of the test temperature by the air cooling mechanism;

[0048] And / or, it also includes a third interval time, which is set according to the transfer of the sample to be tested between the high-temperature tank and the low-temperature tank to ensure that the temperature change rate of the sample to be tested is less than 0.1% during the transfer process.

[0049] In this solution, the first interval time is set to be no less than the time for the sample to be tested to be heated from the set low temperature by the liquid heat transfer medium to the upper limit of the test temperature, ensuring that the sample to be tested has sufficient residence time to be heated to the high temperature, avoiding uneven heating of the sample to be tested, resulting in some samples not being completely heated to the upper limit of the test temperature, thereby improving the effectiveness of the high temperature test. The second interval time is set to be no less than the time for the sample to be tested to be cooled from the set high temperature by the air cooling mechanism to the upper limit of the test temperature, ensuring that the sample to be tested has sufficient residence time to be cooled to the low temperature, avoiding uneven heating of the sample to be tested, resulting in some samples not being completely cooled to the lower limit of the test temperature, thereby improving the effectiveness of the low temperature test. The third interval time is set according to the transfer time of the sample to be tested between the high temperature tank and the low temperature tank, ensuring that the temperature change rate of the sample to be tested is less than 0.1% during the transfer process, avoiding too large temperature changes during the transfer process of the sample to be tested, resulting in too long cooling time for the sample to be tested, thereby affecting the test efficiency.

[0050] The positive and progressive effects of the present invention are as follows: the hot and cold cycle test device and the hot and cold cycle test method of the heat storage material heat the liquid heat transfer medium and then transfer the heat to the test tube immersed therein, thereby transferring the heat to the heat storage material in the test tube, thereby realizing the heat transfer of the liquid heat transfer medium to the heat storage material; compared with air heat transfer, the liquid heat transfer medium is used to uniformly contact the outer surface of the test tube, the heat transfer efficiency is higher, and the heating is faster. There is no need to heat the liquid heat transfer medium to a very high temperature, and the heat can be effectively transferred to the heat storage material, protecting the sample from overheating, and can truly simulate the actual use conditions of the heat storage material, and more accurately evaluate the service life performance of the sample to be tested in the actual working conditions; and the liquid heat transfer medium is used for heat transfer, and the heat transfer is uniform, which is conducive to improving the accuracy of temperature measurement and reducing measurement data errors. The static sample to be tested is heated and cooled respectively by two separate independent chambers, the high temperature tank and the low temperature tank, without affecting each other, which is conducive to improving the test efficiency of hot and cold cycles and the accuracy of temperature control; on this basis, multiple test tubes are tested simultaneously and circulated in the high temperature tank and the low temperature tank through the transmission device, which further improves the test efficiency. By extending one end of the temperature detection device into the static sample to be tested, it is in direct contact with the sample to be tested and is not affected by the fluidity of the sample to be tested, thereby improving the accuracy of temperature control. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 It is a schematic diagram of the three-dimensional structure of the hot and cold cycle testing device of Example 1 of the present invention.

[0052] Figure 2 This is a front view of the hot and cold cycle testing device of Example 1 of the present invention, which shows the internal structure of the upper half of the hot and cold cycle testing device.

[0053] Figure 3 Schematic diagram of the internal structure of the hot and cold cycle testing device of Example 1 of the present invention.

[0054] Figure 4 It is a side view of the hot and cold cycle testing device of Example 1 of the present invention.

[0055] Figure 5 Schematic diagram of the process flow of the hot and cold cycle test method of Example 2 of the present invention.

[0056] Figure 6 This is a charge and discharge thermal cycle temperature curve of a test sample subjected to a thermal cycle test between 450° C. and 150° C. using a thermal cycle test method in Example 2 of the present invention.

[0057] Description of reference numerals:

[0058] Description of reference numerals:

[0059] Door 1

[0060] Door handle 1-1

[0061] Door panel 1-2

[0062] Glass 1-3

[0063] Shell 2

[0064] Fixing screw 2-1

[0065] Stirring device 3

[0066] Driving mechanism 3-2

[0067] Stirring mechanism 3-1

[0068] Partition 3-3

[0069] Sample tray 4

[0070] Test tube 4-1

[0071] Control Display 5

[0072] Fixing screw 6

[0073] Air cooling mechanism 7

[0074] Fan 7-2

[0075] Air duct 7-1

[0076] Roller 8

[0077] Grille 9

[0078] Transmission 10

[0079] Horizontal transmission device 10-2

[0080] Vertical transmission device 10-1

[0081] Low temperature tank 11

[0082] Insulation layer 12

[0083] Heating system 13

[0084] High temperature tank 14 DETAILED DESCRIPTION

[0085] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples.

[0086] Example 1

[0087] This embodiment provides a thermal cycle testing device that can test molten salt or other heat storage materials, and is used to test the thermal cycle life performance of the heat storage material.

[0088] like Figure 1-4 As shown, the hot and cold cycle test device includes a heating system 13, a high temperature tank 14, a low temperature tank 11, a plurality of temperature detection devices (not shown) and an air cooling mechanism 7. The hot and cold cycle test device also includes a plurality of test tubes 4-1 containing samples to be tested and a transmission device 10. The samples to be tested are heat storage materials. The high temperature tank 14 contains a liquid heat transfer medium. The heating system 13 is arranged on the outer wall of the high temperature tank 14 to heat the liquid heat transfer medium. During the test, the samples to be tested in the test tubes are completely immersed in the liquid heat transfer medium, and the heat is transferred to the samples to be tested through the liquid heat transfer medium. One end of the temperature detection device extends into the sample to be tested in the test tube 4-1, and the other end of the temperature detection device and the test tube 4-1 are installed on the transmission device 10. The transmission device 10 is used to drive the test tube 4-1 and the temperature detection device to move back and forth between the high-temperature tank 14 and the low-temperature tank 11, and place the test tube containing the sample to be tested in the high-temperature tank 14 or the low-temperature tank 11 during the test; the air cooling mechanism 7 is arranged at the low-temperature tank 11, and the heat in the low-temperature tank 11 is taken away by suction or blowing or other means to ensure that the temperature of the low-temperature tank 11 is reduced to or below the set lower limit of the test temperature during the test.

[0089] Specifically, in this embodiment, the hot and cold cycle test device is a rectangular frame structure, including a high temperature chamber, a heating system 13, a low temperature chamber, a cooling mechanism, a transmission device 10 and a control display 5. Among them, the shell 2 of the frame structure is separated into two independent chambers, a high temperature chamber and a low temperature chamber, and the high temperature tank 14 and the low temperature tank 11 are respectively installed in the high temperature chamber and the low temperature chamber. The high temperature tank 14 can maintain a constant temperature at a set temperature, which is conducive to the accuracy of measuring the temperature. The transmission device 10 is installed above the high temperature tank 14 and the low temperature tank 11, and spans the high temperature tank 14 and the low temperature tank 11. The frame structure located above the high temperature chamber and the low temperature chamber is provided with two doors 1 that can be opened in half. The door 1 includes a door handle 1-1, a door panel 1-2 and a glass 1-3. The door 1 is convenient for observing the test situation and maintenance. Fixing screws 6 and 2-1 are assembled on different sides of the shell 2 to enhance the structural strength. A control display 5 is also installed on the shell 2 located at the low temperature chamber, which is used to set the control parameters of the test and display the parameters and status of the test. A grille 9 is also provided on the surface of the bottom shell 2 to facilitate heat dissipation. Four rollers 8 are also installed at the four corners of the bottom of the frame structure, so that the hot and cold cycle test device can be moved for testing.

[0090] In this embodiment, the liquid heat transfer medium is liquid molten salt, and the high temperature tank 14 is a high temperature molten salt tank. The material thereof is selected according to the upper limit use temperature of the molten salt sample to be tested. It can be carbon steel, stainless steel or nickel-based alloy, etc. In order to reduce corrosion, 316L, 310s stainless steel or nickel-based alloy is preferred. Liquid molten salt is a molten salt heat storage material with high reliability, good stability and low corrosiveness. It can be nitrate or carbonate, and a suitable molten salt material is selected according to the upper limit use temperature of the test sample. For example, the upper limit use temperature of the conventional test molten salt sample is lower than 560°C, preferably solar binary salt (60wt% sodium nitrate + 40wt% potassium nitrate, melting point of about 220°C) or potassium nitrate monosalt (melting point of about 330°C), such as the upper limit use temperature of the test sample is between 560°C and 750°C, preferably a combination of 31.9wt% sodium carbonate, 31.3wt% potassium carbonate and 36.7wt% lithium carbonate (melting point of about 398°C). Wherein, wt% is weight percentage. Test tube 4-1 is used to store the molten salt sample to be tested. The material of test tube 4-1 can be carbon steel, stainless steel or nickel-based alloy, preferably 310s stainless steel, and the volume of test tube 4-1 is 15~30ml. There are multiple test tubes 4-1, and multiple groups of molten salt samples can be tested at the same time. Multiple test tubes 4-1 are evenly installed on the sample tray 4, and the sample tray 4 is installed on the transmission device 10. The sample tray 4 moves as a whole with multiple test tubes 4-1. The low temperature tank 11 is a container for air-cooled test tube 4-1, and its material can be carbon steel, aluminum alloy or stainless steel. To avoid corrosion of the container, stainless steel material, such as 316L, 310s, etc., is preferred; the structure of the low temperature tank 11 is cylindrical or cubic.

[0091] In other embodiments, the material, shape and size of the high-temperature tank 14 and the low-temperature tank 11 can be adjusted accordingly as needed, and the number, size and volume of the test tubes 4-1 can also be adjusted accordingly as needed. The sample tray 4 can also be omitted, and multiple test tubes 4-1 can be directly installed on the transmission device 10.

[0092] When the hot-cold cycle test device of this embodiment is used to perform a hot-cold cycle test, when the test tube 4-1 containing the sample to be tested is heated in the high-temperature tank 14 and raised to the upper limit of the test temperature, the test tube 4-1 can also be kept in the high-temperature tank 14 for a period of time according to the needs of the test effect; similarly, when the test tube 4-1 containing the sample to be tested is cooled in the low-temperature tank 11 and lowered to the lower limit of the test temperature, the test tube 4-1 can also be kept in the low-temperature tank 11 for a period of time. The cooling of the low-temperature tank 11 by the air cooling mechanism 7 must ensure that the temperature of the low-temperature tank 11 is reduced to or below the set lower limit of the test temperature during the test, but in order to maintain the low temperature, the air cooling mechanism 7 can also be allowed to work all the time during the entire test process to maintain a stable low-temperature environment.

[0093] The hot and cold cycle test device for heat storage materials heats the liquid heat transfer medium in the high-temperature tank 14 through the heating system 13, and the liquid heat transfer medium transfers the heat to the test tube 4-1 immersed therein, thereby transferring the heat to the heat storage material in the test tube 4-1, realizing the heat transfer of the liquid heat transfer medium to the heat storage material; compared with air heat transfer, the liquid heat transfer medium is used to uniformly contact the outer surface of the test tube 4-1, the heat transfer efficiency is higher, and the heating is faster. There is no need to heat the liquid heat transfer medium to a very high temperature, and the heat can be effectively transferred to the heat storage material to protect the sample from overheating. It can truly simulate the actual use conditions of the heat storage material and more accurately evaluate the service life performance of the sample to be tested under actual conditions; and the liquid heat transfer medium is used for heat transfer, and the heat transfer is uniform, which is conducive to improving the accuracy of temperature measurement and reducing measurement data errors. The static sample to be tested is heated and cooled respectively by two separate independent chambers, the high temperature tank 14 and the low temperature tank 11, without affecting each other, which is conducive to improving the test efficiency of the hot and cold cycle and the accuracy of temperature control; on this basis, multiple test tubes 4-1 are tested simultaneously, and the transmission device 10 is used to circulate in the high temperature tank 14 and the low temperature tank 11, which further improves the test efficiency. By extending one end of the temperature detection device into the static sample to be tested, it is directly in contact with the sample to be tested and is not affected by the fluidity of the sample to be tested, thereby improving the accuracy of temperature control. The heat in the low temperature tank is taken away by the air cooling mechanism so that it does not exceed the set lower limit of the test temperature, thereby improving the cooling speed during low temperature testing.

[0094] The heating system 13 may be a heating wire or an infrared electric heater, preferably an infrared electric heater. Figure 3 As shown, the heating system 13 is wrapped around the outer wall of the high temperature tank 14, which is beneficial to the uniformity of heating, the accuracy of temperature control, and the improvement of heating efficiency; for the convenience of maintenance, an infrared electric heater composed of two or more pieces can be used. In other embodiments, the type of the heating system 13 can be selected according to the effect requirements, and its setting position can also be adjusted accordingly according to the effect requirements.

[0095] As mentioned above, a suitable liquid heat transfer medium is selected according to the upper limit use temperature of the test sample. Specifically, the selection condition of the liquid heat transfer medium is that its maximum temperature after being heated is not lower than the set upper limit of the test temperature of the sample to be tested, and the upper limit of the test temperature is determined according to the upper limit use temperature of the test sample in actual use, to ensure that the maximum temperature of the liquid heat transfer medium after being heated is not lower than the upper limit of the test temperature, and there is enough heating temperature space to meet the requirements of the cyclic high temperature test. In other embodiments, if the maximum temperature of the liquid heat transfer medium after being heated is lower than or close to the set upper limit of the test temperature, it can also reflect the high temperature test performance to a certain extent, but its test effect is not as good as the conditions set in this embodiment, and it cannot truly simulate the actual working conditions.

[0096] Among them, Figure 3 As shown, the outside of the heating system 13 and the high-temperature tank 14 is also wrapped with a heat-insulating layer 12, which can reduce heat loss, help shorten the heating process, and improve test efficiency.

[0097] In order to avoid cold areas in the high temperature tank 14 and make the temperature field of the liquid heat transfer medium more uniform, the structure of the high temperature tank 14 is preferably a cylindrical structure or at least a hemispherical structure at the bottom. Figure 3 As shown, in this embodiment, the high temperature tank 14 is a metal container with a hemispherical structure at the bottom and a cylindrical structure at the top. The high temperature tank 14 adopts a cylindrical structure or a hemispherical structure at the bottom, which increases the contact area of ​​the liquid heat transfer medium, avoids the cold zone in the high temperature tank 14, makes the temperature field of the liquid heat transfer medium more uniform, and is conducive to the accuracy of temperature control and improves the heating efficiency.

[0098] Among them, Figure 1-3 As shown, in order to further make the temperature field in the high-temperature tank 14 more uniform, in this embodiment, the hot and cold cycle test device is equipped with a stirring device 3, and the stirring device 3 includes a driving mechanism 3-2 and a stirring mechanism 3-1. The driving mechanism 3-2 is specifically a motor, which is arranged at a position far away from the high-temperature tank 14 to prevent the high temperature in the high-temperature tank 14 from being transmitted to the driving mechanism 32 and damaging the stirring motor. Further, in order to prevent the stirring mechanism 3-1 from transmitting the high temperature in the high-temperature tank 14 to the stirring motor, the stirring mechanism 3-1 adopts a reciprocating eccentric connecting rod structure, which includes an eccentric wheel, a connecting rod and a stirring member (not shown in the figure), the output shaft of the motor is connected to the eccentric wheel, and the two ends of the connecting rod are respectively connected to the eccentric wheel and the stirring member, and the stirring member is specifically a stirring paddle, and its bottom end portion extends into the liquid heat transfer medium of the high-temperature tank 14. The stirring motor drives the eccentric wheel to realize eccentric reciprocating motion, thereby driving the stirring paddle through the connecting rod to realize eccentric reciprocating motion, so that the stirring paddle reciprocates and stirs the liquid molten salt to realize the stirring function.

[0099] In other embodiments, the stirring device 3 may be omitted, and the uniformity of the temperature field can be achieved by relying on the uniform distribution of the heating system 13 on the outer wall of the high-temperature tank 14. If a stirring device 3 is used, there are multiple stirring methods, and different stirring devices 3 can be selected according to the stirring effect and the needs of the specific structure. However, it is preferred to adopt the reciprocating eccentric connecting rod stirring structure of this embodiment, and the stirring member is extended into the liquid heat transfer medium for reciprocating stirring, which is beneficial to the temperature uniformity of the liquid heat transfer medium at different positions in the high-temperature tank 14, and is beneficial to improving the accuracy of temperature measurement and reducing measurement data errors. In addition, if the prior art uses water or oil to cool the stirring rod, there may be a risk of leakage, while the stirring device 3 of this embodiment can avoid the risk of explosion caused by the contact between molten salt and organic matter or water at high temperature.

[0100] Among them, Figure 2As shown, a partition 3-3 is provided between the driving mechanism 3-2 and the stirring mechanism 3-1. The partition 3-3 supports the stirring mechanism 3-1 to achieve reciprocating stirring on the one hand, and can further insulate the driving mechanism 3-2 on the other hand.

[0101] In a low temperature room, Figure 3 As shown, the air cooling mechanism 7 includes a fan 7-2 and an air duct 7-1. An air outlet is provided at the bottom of the low temperature tank 11. The fan 7-2 is arranged below the low temperature tank 11, and the air inlet of the fan 7-2 is arranged opposite to the air outlet of the low temperature tank 11. The fan 7-2 is a variable frequency suction fan. When the test tube 4-1 is heated in the high temperature tank 14 and moved into the low temperature tank 11, the high temperature test tube 4-1 will release heat in the low temperature tank 11. The heat makes the airflow in and around the low temperature tank 11 hot and the temperature rises. The internal temperature can be sucked into the external environment through the suction of the fan 7-2. The wind speed of the variable frequency suction fan 7-2 can be adjusted as needed to match the heat release rate of the product, realize the function of controlling the heat release rate of the sample, and reduce the air temperature of the upper part of the hot and cold cycle test device, thereby improving the reliability of the system. One end of the air duct 7-1 is connected to the fan 7-2, and the other end is connected to the external environment, so as to discharge the hot air flow sucked by the fan 7-2 to the outside of the housing 2 of the cold and hot cycle device.

[0102] The hot and cold cycle device adopts such an air cooling mechanism 7, and the fan 7-2 takes away the heat released by the heated test tube 4-1 in the low temperature tank 11 by suction, thereby cooling the sample to be tested in the test tube 4-1. In other embodiments, the heat on the surface of the test tube 4-1 can also be blown away by blowing air, but compared with the blowing cooling method, the present embodiment adopts the suction method to achieve cooling, the airflow is more stable, and the heat is taken out of the low temperature tank 11 faster.

[0103] like Figure 2As shown, the transmission device 10 includes a horizontal transmission device 10-2 and a vertical transmission device 10-1. Specifically, in this embodiment, the horizontal transmission device 10-2 and the vertical transmission device 10-1 both slide horizontally or vertically in a spiral transmission manner, so the horizontal transmission device 10-2 is also called a horizontal spiral slide bar, and the vertical transmission device 10-1 is also called a vertical spiral slide bar. Among them, the horizontal spiral slide bar performs horizontal spiral motion, including an origin, a left control point and a right control point. The origin is the initial position point before the equipment starts the cycle test. The left control point is a control point for temperature detection in the high temperature tank 14 and controlling the heating temperature. The right control point is a control point for temperature detection in the low temperature tank 11 and controlling the cooling temperature. The vertical spiral slide bar realizes the lifting and lowering action in the high temperature tank 14 and the low temperature tank 11, and is connected to the horizontal spiral slide bar by sliding in the horizontal direction. The test tube 4-1 is installed on the vertical spiral slide bar together with the sample tray 4 and the temperature detection device. The vertical spiral slide bar drives the sample tray 4 and the temperature detection device to perform vertical reciprocating lifting motion and move together on the horizontal spiral slide bar. When the sample tray 4 moves to the fixed position of the high temperature tank 14 with the vertical spiral slide bar, about 2 / 3 of the position of the test tube 4-1 is immersed in the liquid molten salt. The transmission device 10 realizes the lifting and moving of the test tube 4-1 and the temperature detection device through the coordinated operation of the transmission devices in two different directions, horizontally and vertically, and heats in the high temperature tank 14 and releases heat in the low temperature tank 11, respectively, thereby realizing the reciprocating cycle function of charging and releasing heat.

[0104] In other embodiments, the specific structure and transmission method of the transmission device 10 can be adjusted accordingly according to the needs of the specific structure, and is not limited to the combination of the horizontal transmission device 10-2 and the vertical transmission device 10-1 of this embodiment.

[0105] In this embodiment, the temperature detection device is a temperature measuring thermocouple, which extends from the vertical spiral slide bar and the top of the test tube 4-1 into the interior of the test tube 4-1. During the charging and discharging heat cycle of the molten salt sample to be tested, the top of the test tube 4-1 can be covered and perforated to fix the temperature measuring probe of the temperature measuring thermocouple, and the temperature sensor line of the temperature measuring thermocouple can be fixed on the horizontal spiral slide bar and the vertical spiral slide bar.

[0106] Among them, the temperature detection device extends into one end of the sample to be tested (i.e., the temperature measuring probe of the thermocouple) and is spaced apart from the inner wall of the test tube 4-1, keeping the relative position unchanged and not touching the test tube 4-1, forming a suspended state, so that the temperature measurement point truly reflects the heated temperature of the sample to be tested, and is not affected by the temperature of the test tube 4-1 and outside the test tube 4-1, thereby improving the accuracy of temperature detection and ensuring the reliability of testing the temperature of the molten salt sample.

[0107] In this embodiment, the liquid heat transfer medium is liquid molten salt. In other embodiments, the heat exchange medium may also be other substances other than liquid molten salt that can effectively transfer heat to the heat storage material to be tested without being heated to a very high temperature. Generally, such a heat transfer medium is preferably liquid. Compared with other heat transfer media, this embodiment uses liquid molten salt as the heat transfer medium, which utilizes the good thermal conductivity of molten salt. On the one hand, it is conducive to improving the heating efficiency. On the other hand, it does not need to heat the liquid molten salt to a very high temperature to effectively transfer heat to the sample to be tested, ensuring that the sample will not overheat, and can truly simulate the actual use conditions of the heat storage material, and more accurately evaluate the service life performance of the sample to be tested in actual working conditions.

[0108] Among them, the control display 5 includes control logic and display interface, and the parameters of the display interface include: the temperature of the temperature measuring point of the molten salt sample, or the test time of the molten salt sample, the moving speed of the horizontal transmission device 10-2 and the vertical transmission device 10-1, the temperature of the liquid molten salt in the high temperature tank 14, the air temperature of the low temperature tank 11, the stirring switch state, the electric heating switch state, the frequency and switch state of the fan 7-2, the tank body temperature of the low temperature tank 11, the total set number of cycles, the number of cycles, the upper limit use temperature of the molten salt sample, the lower limit use temperature, the temperature of the sample in each test tube 4-1, and the temperature change curve of the test sample, the molten salt in the high temperature tank 14 and the low temperature tank 11 over time. The built-in control logic of the control display 5 is divided into two control modes: test sample temperature control and time control mode, that is, the hot and cold cycle device of this embodiment has two different operating modes: temperature control mode and time control mode. When the temperature control mode is selected on the control display 5, whether the temperature of the sample to be tested in the test tube 4-1 reaches the set temperature upper limit and temperature lower limit is used as a control condition to determine whether the test tube 4-1 moves from the high temperature tank 14 to the low temperature tank 11, or from the low temperature tank 11 to the high temperature tank 14. When the time control mode is selected on the control display 5, whether the residence time of the sample to be tested in the test tube 4-1 in the high temperature tank 14 or the low temperature tank 11 reaches the set interval time is used as a control condition to determine whether the test tube 4-1 moves from the high temperature tank 14 to the low temperature tank 11, or from the low temperature tank 11 to the high temperature tank 14. Users can select different operation control modes according to actual test needs.

[0109] Example 2

[0110] This embodiment provides a method for hot and cold cycle testing of a heat storage material. The method utilizes a hot and cold cycle testing device for the heat storage material of Embodiment 1 to perform hot and cold cycle testing.

[0111] like Figure 5 As shown, the hot and cold cycle test method includes the following steps:

[0112] S1, start the heating system 13;

[0113] S2, enter the hot and cold cycle test mode, each hot and cold cycle test includes the following steps:

[0114] S2.1, heating the liquid heat transfer medium in the high temperature tank 14;

[0115] S2.2, immersing several test tubes 4-1 simultaneously or successively into the liquid heat transfer medium in the high temperature tank 14, and heating the samples to be tested in the test tubes 4-1;

[0116] S2.3, using a temperature detection device to detect the temperature of the sample to be tested;

[0117] S2.4, judging whether the state of the sample to be tested in the high temperature tank 14 satisfies the set first control point, the first control point being whether the temperature of the sample to be tested reaches the set upper limit of the test temperature and / or whether the residence time of the sample to be tested in the high temperature tank 14 reaches the set first interval time;

[0118] S2.5. If the conditions are met, the transmission device 10 is used to lift the test tube 4-1 and the temperature detection device and move them into the low temperature tank 11;

[0119] S2.6, use the air cooling mechanism 7 to act on the low temperature tank 11 to take away the heat in the low temperature tank 11, so as to ensure that the temperature of the low temperature tank 11 is reduced to or below the set lower limit of the test temperature during the test; in this embodiment, the air cooling mechanism 7 takes away the heat released by the test tube 4-1 after being heated in the high temperature tank 14 and then extended into the low temperature tank 11 by sucking the air flow in the low temperature tank 11 or blowing air into the low temperature tank 11;

[0120] S2.7, judging whether the state of the sample to be tested in the cryogenic tank 11 satisfies the set second control point, the second control point being whether the temperature of the sample to be tested reaches the set lower limit of the test temperature and / or whether the residence time of the sample to be tested in the cryogenic tank 11 reaches the set second interval time;

[0121] S3, if the state of the sample to be tested in the low temperature tank 11 satisfies the set second control point, repeat step S2 and calculate the number of cycles;

[0122] S4, judging whether the number of cycles reaches the set number;

[0123] S5. If the set number of times is reached, the test is stopped and the heating system 13 is turned off.

[0124] The hot and cold cycle test method of the heat storage material can realistically simulate the actual use conditions of the heat storage material through the above steps, more accurately evaluate the service life performance of the sample to be tested under actual conditions; and improve the test efficiency and the accuracy of temperature control. If multiple test tubes 4-1 are immersed in a liquid heat transfer medium for heating at the same time, the amount of samples to be tested is increased, thereby improving the test efficiency; if multiple test tubes 4-1 are loaded with different samples to be tested, and multiple test tubes 4-1 are successively immersed in a liquid heat transfer medium for heating, the service life performance of different samples to be tested can be compared. The first control point and the second control point respectively realize two different logic controls in the form of temperature control (test temperature upper limit or test temperature lower limit) and residence time, meeting different performance evaluation requirements of the cycle test.

[0125] When the hot and cold cycle test device includes a stirring device 3 , the step S2 further includes: using a stirring member to extend into the liquid heat transfer medium in the high temperature tank 14 to stir the liquid heat transfer medium.

[0126] The stirring member is extended into the liquid heat transfer medium for stirring, which is beneficial to the temperature uniformity of the liquid heat transfer medium at different positions in the high-temperature tank 14, and is beneficial to improving the accuracy of temperature measurement and reducing measurement data errors.

[0127] Among them, in step S2, if whether the temperature of the sample to be tested reaches the set test temperature upper limit is selected as the first control point, and whether the temperature of the sample to be tested reaches the set test temperature lower limit is selected as the second control point, that is, the operation mode of the hot and cold cycle device is set to the temperature control mode, then the specific operation of the hot and cold cycle test method can be: the sample temperature in any test tube 4-1 can be selected as the control point, the temperature of the high-temperature tank 14 filled with liquid molten salt is set (slightly higher than the test upper limit use temperature), the upper limit use temperature and the lower limit use temperature are used to set the sample cycle temperature range, and the moving speeds of the horizontal spiral slide bar and the vertical spiral slide bar are set, And turn on the fan 72 and electric heating. When the temperature of the liquid molten salt in the high-temperature tank 14 reaches the set heating temperature value, start stirring and measure the number of heat charging and discharging cycles. The sample to be tested is first moved from the origin of the horizontal spiral slide bar to the high-temperature tank 14 for heating and temperature increase. When the sample reaches the upper limit of the use temperature, the horizontal spiral slide bar and the vertical spiral slide bar move the test tube 4-1 to the low-temperature tank 11. When the sample cools down to the lower limit of the use temperature, it is a cycle; the vertical spiral slide bar pulls the test tube 4-1 containing the molten salt sample and moves it to the high-temperature tank 14, and reciprocates. When the number of cycles reaches the set number, the cycle stops, and the cycle temperature curve of the molten salt sample during the heat charging and discharging process is recorded. Then, by testing the molten salt sample, recording its DSC curve (DSC=Differential Scanning Calorimetry, i.e., the curve obtained by differential scanning calorimetry) at different times of the cycle, the melting point, initial crystallization point, and composition changes are obtained to examine the high-temperature cycle stability of the molten salt material. It is a prior art to test a molten salt sample using the principle of differential scanning calorimetry to obtain a DSC curve, which will not be described in detail here.

[0128] Figure 6 The example shows the charge and discharge heat cycle curve obtained by using the hot and cold cycle test method to conduct medium and high temperature hot and cold cycle tests. The temperature of the high-temperature tank 14 is set to 460°C, the cycle temperature range of the molten salt sample is set to 450~150°C, and the number of cycles is set to 500 times. There are 8 samples in total, corresponding to 8 test tubes 4-1; the temperature control point is set to the molten salt sample in test tube No. 3 4-1. When sample No. 3 reaches 450°C in the high-temperature tank 14, the lifting transmission device 10 moves the molten salt sample to the low-temperature tank 11. When sample No. 3 reaches 150°C, the lifting device moves the molten salt to the high-temperature tank 14, and the cycle is repeated 500 times; samples are taken and the DSC curve of the samples is tested; the cycle is repeated to 3000 times, and the DSC sampling and composition changes of the samples are tested to investigate the cycle stability of the molten salt samples between 450°C and 150°C.

[0129] Among them, in step S2, if the first interval time for the sample to be tested to stay in the high-temperature tank 14 is selected as the first control point, and the second interval time for the sample to be tested to stay in the low-temperature tank 11 is selected as the second control point, that is, the operation mode of the hot and cold cycle device is set to the time control mode, at this time, the set first interval time is not less than the time for the sample to be tested to be heated from the set low temperature to the set test temperature upper limit by the liquid heat transfer medium. Such high-temperature residence time can be calculated according to certain rules (for example; average value) based on the heating time obtained by multiple test samples to obtain a reasonable high-temperature residence time, ensuring that the sample to be tested has sufficient residence time to be heated to a high temperature, avoiding uneven heating of the sample to be tested, resulting in some samples not being fully heated to the test temperature upper limit, thereby improving the effectiveness of the high-temperature test. Similarly, the set second interval time is not less than the time it takes for the sample to be tested to be cooled from the set high temperature to the set lower limit of the test temperature by the air cooling mechanism. Such low-temperature residence time can also be calculated based on the cooling time obtained from multiple test samples and certain rules to obtain a reasonable low-temperature residence time, thereby ensuring that the sample to be tested has sufficient residence time to be cooled to a low temperature, avoiding uneven heating of the sample to be tested, which may cause some samples to not be completely cooled to the lower limit of the test temperature, thereby improving the effectiveness of the low-temperature test.

[0130] In the time control mode, step S2 also includes a third interval time, which is an interval time set according to the transfer of the sample to be tested between the high-temperature tank and the low-temperature tank, ensuring that the temperature change rate of the sample to be tested is less than 0.1% during the transfer process; this avoids the temperature change of the sample to be tested being too large during the transfer process, which causes the sample to be tested to be cooled for too long, thereby affecting the test efficiency; because if the temperature of the sample to be tested changes too much during the transfer process, the sample to be tested has been cooled to a lower temperature, but is still cooled according to the set second interval time (i.e., the set cooling time), then the sample to be tested may have been cooled to the lower limit of the test temperature long ago, but is limited by the set second interval time and is still cooled in the low-temperature tank, thereby extending the actual required cooling time and affecting the test efficiency.

[0131] In the time control mode, the specific operation of the hot and cold cycle test method can be: any test tube 4-1 can be selected as a control point, the temperature of the high-temperature tank 14 is set (slightly higher than the upper limit of the test temperature), and the residence time of the test tube 4-1 in the high-temperature tank 14 and the residence time of the test tube 4-1 in the low-temperature tank 11 are used as control points, and the moving speeds of the horizontal spiral slide bar and the vertical spiral slide bar are set, the electric heating is turned on, and the fan 72 is turned on. When the temperature of the liquid molten salt in the high-temperature tank 14 reaches the set heating temperature value, the stirring and charging and discharging heat cycle test is started. The molten salt sample is first moved from the origin of the horizontal spiral slide bar to the high-temperature tank 14 for heating and heating. When the residence time of the molten salt sample to be tested in the high-temperature tank 14 reaches the set value, the transmission device 10 moves the test tube 4-1 to the low-temperature tank 11. When the residence time of the test tube 4-1 in the low-temperature tank 11 reaches the set value, it is a cycle; the vertical spiral slide bar pulls the molten salt sample and moves it to the high-temperature tank 14, and reciprocates. When the number of cycles reaches the set number, the cycle stops. Then, by testing the molten salt material samples, recording their DSC curves (DSC = Differential Scanning Calorimetry, that is, the curve obtained by differential scanning calorimetry) under different numbers of charge and discharge cycles, the melting point, initial crystallization point and composition changes are obtained to examine the high-temperature cycle stability of the molten salt material.

[0132] In other embodiments, which mode (the set test temperature limit value of the sample to be tested or the set residence time of the sample to be tested in the high temperature tank 14 / low temperature tank 11) is selected as the first control point and the second control point can be combined accordingly according to the needs of the test, for example, the set upper limit of the test temperature of the sample to be tested is used as the first control point, and the set residence time of the sample to be tested in the low temperature tank 11 is used as the second control point. It is also possible to use both control modes (test temperature limit value and residence time) as control points as needed, and the sample to be tested needs to meet the conditions of both control modes.

[0133] In actual testing, different test tubes 4-1 may be heated at different speeds. Therefore, in step S2, when the first control point is the set upper limit of the test temperature of the sample to be tested, further, the above step S2.4 may be: determine whether the temperature of the sample to be tested with the lowest temperature is not lower than the set upper limit of the test temperature of the sample to be tested. With such judgment conditions, it is ensured that the sample to be tested with the lowest temperature is also completely heated to the upper limit of the test temperature, and the life performance of all samples to be tested can be accurately evaluated. When the second control point is the set lower limit of the test temperature of the sample to be tested, further, the above step S2.7 may be: determine whether the temperature of the sample to be tested with the highest temperature is not higher than the set lower limit of the test temperature of the sample to be tested. With such judgment conditions, it is ensured that the sample to be tested with the highest temperature is also completely cooled to the lower limit of the test temperature, and the life performance of all samples to be tested can be accurately evaluated.

[0134] Although the specific embodiments of the present invention are described above, it should be understood by those skilled in the art that this is only for illustration and the protection scope of the present invention is defined by the appended claims. Those skilled in the art may make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but these changes and modifications all fall within the protection scope of the present invention.

Claims

1. A hot and cold cycle test device for heat storage materials, the hot and cold cycle test device comprising a heating system, a high temperature tank, a low temperature tank, a plurality of temperature detection devices and an air cooling mechanism, characterized in that: The hot and cold cycle test device also includes a plurality of test tubes and a transmission device containing samples to be tested, and the samples to be tested are heat storage materials; The high temperature tank contains a liquid heat transfer medium, and the heating system is used to heat the liquid heat transfer medium. During the test, the sample to be tested in the test tube is completely immersed in the liquid heat transfer medium; One end of the temperature detection device extends into the sample to be tested in the test tube, and the other end of the temperature detection device and the test tube are both installed on the transmission device, and the transmission device drives the test tube and the temperature detection device to move back and forth between the high-temperature tank and the low-temperature tank, and the sample to be tested is placed in the high-temperature tank or the low-temperature tank during testing; The air cooling mechanism is used to take away the heat in the low-temperature tank to ensure that the temperature of the low-temperature tank is reduced to or below the set lower limit of the test temperature during the test.

2. The thermal cycle testing device for heat storage materials according to claim 1, characterized in that: The heating system is wrapped around the outer walls of the high-temperature tank, and / or the outer sides of the heating system and the high-temperature tank are also wrapped with a heat-insulating layer.

3. The thermal cycle test device for heat storage materials according to claim 1, characterized in that: The maximum temperature at which the selected liquid heat transfer medium is heated is not lower than the set upper limit of the test temperature of the sample to be tested.

4. The thermal cycle testing device for heat storage materials according to claim 1, characterized in that: The hot and cold cycle testing device further comprises a stirring device, wherein the stirring device comprises a stirring member, at least a portion of which extends into the liquid heat transfer medium in the high temperature tank for stirring the liquid heat transfer medium.

5. The thermal cycle testing device for heat storage materials according to claim 4, characterized in that: The stirring device also includes a driving mechanism and a stirring mechanism. The driving mechanism is arranged at a position far away from the high-temperature tank. The stirring mechanism includes an eccentric wheel, a connecting rod and the stirring member. The output shaft of the driving mechanism is connected to the eccentric wheel, and the two ends of the connecting rod are respectively connected to the eccentric wheel and the stirring member.

6. The thermal cycle testing device for heat storage materials according to claim 5, characterized in that: A partition is provided between the driving mechanism and the stirring mechanism.

7. The thermal cycle test device for heat storage materials according to claim 1, characterized in that: The air cooling mechanism includes a fan and an air duct, an air outlet is provided on the low temperature tank, and the air intake of the fan is arranged opposite to the air outlet of the low temperature tank; The fan is connected to the air duct, the air duct is connected to the external environment, and the fan is used to suck the air flow in the low-temperature tank.

8. The thermal cycle testing device for heat storage materials according to claim 1, characterized in that: The transmission device includes a horizontal transmission device and a vertical transmission device. The vertical transmission device is slidably connected to the horizontal transmission device in the horizontal direction. The test tube and the temperature detection device are installed at the lower end of the vertical transmission device. The vertical transmission device drives the test tube and the temperature detection device to move in the vertical direction and move together in the horizontal direction along the horizontal transmission device.

9. The thermal cycle testing device for thermal storage materials according to any one of claims 1 to 8, characterized in that: The temperature detection device extends into one end of the sample to be tested and is spaced apart from the inner wall of the test tube; and / or the liquid heat transfer medium is liquid molten salt.

10. A method for testing the thermal cycle of a heat storage material, characterized in that: The hot and cold cycle test method uses a hot and cold cycle test device for the heat storage material according to any one of claims 1 to 9 to perform a hot and cold cycle test, and the hot and cold cycle test method comprises the following steps: S1, starting the heating system; S2, enter the hot and cold cycle test mode, each hot and cold cycle test includes the following steps: heating the liquid heat transfer medium in the high temperature tank; Immersing a plurality of the test tubes in the liquid heat transfer medium in the high temperature tank, and heating the samples to be tested in the test tubes; Using the temperature detection device to detect the temperature of the sample to be tested; Determine whether the state of the sample to be tested in the high-temperature tank satisfies a set first control point, wherein the first control point is whether the temperature of the sample to be tested reaches a set test temperature upper limit and / or whether the residence time of the sample to be tested in the high-temperature tank reaches a set first interval time; If the conditions are met, the test tube and the temperature detection device are lifted by the transmission device and moved into the low-temperature tank; Using the air cooling mechanism to act on the low temperature tank to take away the heat in the low temperature tank, so as to ensure that the temperature of the low temperature tank is reduced to or below the set lower limit of the test temperature during the test; Determine whether the state of the sample to be tested in the low temperature tank meets a set second control point, wherein the second control point is whether the temperature of the sample to be tested reaches a set lower limit of the test temperature and / or whether the residence time of the sample to be tested in the low temperature tank reaches a set second interval time; S3, if the state of the sample to be tested in the low temperature tank meets the set second control point, repeat the step S2 and calculate the number of cycles; S4, determining whether the number of cycles reaches a set number; S5. If the set number of times is reached, the test is stopped and the heating system is turned off.

11. The method for testing the thermal storage material for thermal cycles according to claim 10, characterized in that: In the step S2, the first control point is whether the temperature of the sample to be tested reaches the set test temperature upper limit, and the step of "determining whether the state of the sample to be tested in the high-temperature tank meets the set first control point" specifically includes: determining whether the temperature of the sample to be tested with the lowest temperature is not lower than the set test temperature upper limit; and / or, In step S2, the second control point is the set lower limit of the test temperature of the sample to be tested, and the step of "determining whether the state of the sample to be tested in the low-temperature tank meets the set second control point" specifically includes: determining whether the temperature of the sample to be tested with the highest temperature is not higher than the set lower limit of the test temperature.

12. The method for testing the thermal storage material for thermal cycles according to claim 10, characterized in that: The hot and cold cycle test device further includes a stirring device, and the stirring device includes a stirring member. Step S2 further includes the following steps: The stirring member is used to extend into the liquid heat transfer medium in the high-temperature tank to stir the liquid heat transfer medium.

13. The method for testing the thermal storage material for thermal cycles according to claim 10, characterized in that: In the step S2, The first interval time is not less than the time it takes for the sample to be tested to be heated from a set low temperature by the liquid heat transfer medium to a set upper limit of the test temperature; and / or, The second interval time is not less than the time it takes for the sample to be tested to be cooled from a set high temperature to a set lower limit of the test temperature by the air cooling mechanism; and / or, It also includes a third interval time, which is set according to the transfer of the sample to be tested between the high-temperature tank and the low-temperature tank to ensure that the temperature change rate of the sample to be tested is less than 0.1% during the transfer process.

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