Low-temperature apparent thermal conductivity testing device

Abstract

The invention relates to the technical field of measuring devices, and provides a low-temperature apparent thermal conductivity testing device which comprises a heat regenerator shell, a refrigerator, an inflation mechanism, a heater, a first temperature detection element and a second temperature detection element. A cold head of the refrigerating machine is connected with the first end of the heat regenerator shell. A gas medium is filled into the heat regenerator shell by the gas filling mechanism; the heater comprises a heating piece and a constant current source instrument, the heating piece heats the second end of the heat regenerator shell, and the constant current source instrument outputs constant current to the heating piece; the first temperature detection element detects the temperature of the first end of the heat regenerator shell; the second temperature detection element is suitable for detecting the temperature of the second end of the heat regenerator shell. Therefore, the apparent thermal conductivity of the cold storage material is measured and calculated according to a steady-state axial heat flow method, and the heat regenerator loss is determined by determining the apparent thermal conductivity of the cold storage material. The actual working condition of the cold storage material in the refrigerator regenerator can be simulated in the measurement process, and the determination result of the regenerator loss is more accurate.

Description

Technical Field

[0001] The present invention relates to the technical field of measuring devices, in particular to a low-temperature apparent thermal conductivity testing device. Background Art

[0002] A regenerative chiller, also known as a regenerative chiller or thermal storage chiller, is a device that utilizes a regenerator (heat accumulator) to store and release heat to achieve a refrigeration cycle. The regenerator is a key component in a regenerative chiller, absorbing heat from the outside world while releasing heat stored during the previous cycle as the refrigerant flows through it, thereby reducing the temperature. The regenerator in a regenerative chiller experiences certain losses during operation, and this loss is a key factor in determining the chiller's cooling performance.

[0003] In the related art, when determining the regenerator loss, it is mainly achieved by calculating the thermal diffusivity or thermal penetration depth of the cold storage material. The calculation of the thermal diffusivity and thermal penetration depth of the cold storage material is based on the physical parameters of the cold storage material itself, such as thermal conductivity, specific heat capacity, and density. After the cold storage material is filled into the outer shell of the regenerator, the axial heat leakage loss of the regenerator is not only related to the thermal properties of the cold storage material itself, but also to the gas working medium in the regenerator, the filling method of the cold storage material, etc. The regenerator loss is determined only by calculating the thermal diffusivity or thermal penetration depth of the cold storage material based on the thermal properties of the cold storage material itself, resulting in the determined regenerator loss being not accurate enough.

[0004] Therefore, how to solve the problem of inaccurate determination results of regenerator losses in related technologies has become an important technical problem to be solved by those skilled in the art. Summary of the Invention

[0005] The present invention provides a low-temperature apparent thermal conductivity testing device, which is used to solve the defect of inaccurate determination results of regenerator losses in the related art.

[0006] The present invention provides a low-temperature apparent thermal conductivity testing device, comprising: A regenerator shell suitable for accommodating the cold storage material to be tested; a refrigerator, adapted to cool the regenerator shell, a cold head of the refrigerator being connected to the first end of the regenerator shell; a charging mechanism, adapted to charge gaseous medium into the regenerator shell; a heater, comprising a heating element and a constant current source instrument, wherein the heating element is connected to the second end of the regenerator shell, the heating element is adapted to heat the second end of the regenerator shell, and the constant current source instrument is adapted to output a constant current to the heating element; a first temperature detection element, disposed at the first end of the regenerator shell, the first temperature detection element being adapted to detect the temperature of the first end of the regenerator shell; The second temperature detection element is provided at the second end of the regenerator shell, and the second temperature detection element is suitable for detecting the temperature of the second end of the regenerator shell.

[0007] According to a low-temperature apparent thermal conductivity testing device provided by the present invention, the regenerator shell comprises: The housing is a cylindrical structure with one end open, the housing comprising a shell with both ends open, a first flange, and a second flange, the first flange closing one end opening of the shell, the second flange being provided at the other end of the shell, the first flange being connected to the cold head of the refrigerator, the first temperature detection element being provided at the first flange, and an inflation hole being provided on a side wall of the shell, the inflation hole being adapted to be connected to the inflation end of the inflation mechanism; The cover is adapted to close the open end of the shell. The cover is detachably and sealedly connected to the second flange. The heating element is arranged on a side of the cover away from the shell. The second temperature detection element is arranged on the cover.

[0008] A low-temperature apparent thermal conductivity testing device provided by the present invention further includes: A thermal damping plate is provided between the first end of the regenerator shell and the cold head of the refrigerator, and is suitable for reducing temperature fluctuations transmitted from the cold head of the refrigerator to the regenerator shell.

[0009] According to a low-temperature apparent thermal conductivity testing device provided by the present invention, the thermal damping sheet includes an epoxy sheet, a brass sheet, or a laminated sheet composed of glass fiber cloth and epoxy resin.

[0010] A low-temperature apparent thermal conductivity testing device provided by the present invention further includes: A heat insulation cover is provided on the outside of the cold head of the refrigerator, the regenerator shell and the heating element. The heat insulation cover is suitable for reducing heat transfer between the cold head of the refrigerator and the external environment, reducing heat transfer between the regenerator shell and the external environment, and reducing heat transfer between the heating element and the external environment.

[0011] According to a low-temperature apparent thermal conductivity testing device provided by the present invention, the refrigerator has a primary cold head and a secondary cold head, the temperature of the secondary cold head is lower than that of the primary cold head, and the first end of the regenerator shell is connected to the secondary cold head; The heat shield comprises: a cold shield detachably covering the exterior of the primary cold head, the secondary cold head, the regenerator shell, the heating element, the first temperature detection element, and the second temperature detection element, the cold shield being provided with a vent; A vacuum cover is provided on the outside of the cold screen; The vacuum pumping mechanism is suitable for performing a vacuum pumping operation on the vacuum cover and the cold screen.

[0012] According to a low-temperature apparent thermal conductivity testing device provided by the present invention, the refrigerator is a GM refrigerator.

[0013] According to a low-temperature apparent thermal conductivity testing device provided by the present invention, the inflation mechanism includes: a gas storage tank disposed outside the vacuum cover, the gas storage tank being connected to the regenerator shell via a first gas pipeline, the first gas pipeline penetrating the vacuum cover, a sealing structure being provided between the first gas pipeline and the vacuum cover; a pressure detection element, adapted to detect the gas pressure in the gas storage tank; a vacuum pump disposed outside the vacuum cover, wherein the air extraction port of the vacuum pump is connected to the air storage tank via a second air pipeline, wherein the second air pipeline is provided with a control valve, and the control valve is adapted to control the on-off of the second air pipeline; A gas cylinder is arranged outside the vacuum cover, and the gas outlet of the gas cylinder is connected to the gas storage tank through a third gas pipeline. The third gas pipeline is provided with a pressure reducing valve, which is suitable for adjusting the gas pressure in the third gas pipeline downstream of the pressure reducing valve.

[0014] According to a low-temperature apparent thermal conductivity testing device provided by the present invention, the sealing structure includes: a connecting pipe, provided on the vacuum cover, the connecting pipe being suitable for allowing the first gas pipeline to enter and exit the vacuum cover; an end cap, disposed at an end of the connecting pipe away from the vacuum cover, the end cap being sealedly connected to the connecting pipe, and the end cap being provided with a through hole for the first gas transmission pipeline to pass through; A sealing ring is sleeved on the outside of the first gas pipeline, and the sealing ring is tightly fitted to the first gas pipeline; A pressing piece is arranged on a side of the end cover away from the connecting pipe. The pressing piece is threadedly connected to the end cover and is suitable for pressing the sealing ring against the end cover.

[0015] According to a low-temperature apparent thermal conductivity testing device provided by the present invention, the heating element is connected to the constant current source instrument through a first circuit, the first end of the first circuit is connected to the constant current source instrument, the first circuit passes through the vacuum cover and the cold shield and is sequentially wound around the first-level cold head and the second-level cold head, and the second end of the first circuit is connected to the heating element.

[0016] The present invention provides a low-temperature apparent thermal conductivity testing device comprising a regenerator housing, a refrigerator, a gas charging mechanism, a heater, a first temperature detection element, and a second temperature detection element. The regenerator housing is used to accommodate the cold storage material to be tested. The cold head of the refrigerator is connected to the first end of the regenerator housing. The refrigerator is used to cool the regenerator housing to provide a low-temperature environment for the cold storage material to be tested, based on the actual temperature environment of the cold storage material in the regenerator of the actual refrigerator. The gas charging mechanism is used to fill the regenerator housing with a gaseous medium to simulate the actual gaseous environment of the cold storage material to be tested in the regenerator of the actual refrigerator. This ensures that the test environment of the cold storage material to be tested is consistent with the actual environment in the regenerator of the actual refrigerant, thereby improving the accuracy of the measurement results. The heater includes a heating element and a constant current source instrument. The constant current source instrument is used to output a constant current to the heating element to generate a constant heat flow. The constant current source instrument can be used to obtain the current value supplied to the heating element. Combined with the resistance value of the heating element, the heat flow value supplied to the regenerator housing can be calculated and determined. A heating element is connected to the second end of the regenerator shell and is configured to heat the second end of the regenerator shell. A first temperature sensing element is disposed at the first end of the regenerator shell and is configured to detect the temperature of the first end of the regenerator shell. A second temperature sensing element is disposed at the second end of the regenerator shell and is configured to detect the temperature of the second end of the regenerator shell. The temperature difference between the two ends of the regenerator shell can be calculated based on the detection results of the first and second temperature sensing elements. The apparent thermal conductivity of the cold storage material can be calculated based on Fourier's law of heat conduction, taking into account the length and cross-sectional area of ​​the regenerator shell. With this arrangement, the apparent thermal conductivity of the cold storage material is measured and calculated using the steady-state axial heat flow method, and the regenerator loss is determined by determining the apparent thermal conductivity of the cold storage material. This measurement process simulates the actual operating conditions of the cold storage material within the refrigerator regenerator, resulting in a more accurate and realistic determination of the regenerator loss, thus resolving the issue of inaccurate regenerator loss determination in related art. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the present invention or the prior art, a brief introduction is given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 It is a schematic diagram of the working principle of the low-temperature apparent thermal conductivity testing device provided by the present invention.

[0019] Figure 2 It is a schematic diagram of the sealing structure between the first gas transmission pipeline and the vacuum cover provided by the present invention.

[0020] Reference numerals: 1. Heating element; 2. First temperature detection element; 3. Second temperature detection element; 4. Housing; 5. First flange; 6. Second flange; 7. Cover plate; 8. Thermal damping plate; 9. First-stage cold head; 10. Second-stage cold head; 11. Cold screen; 12. Vacuum cover; 13. Gas storage tank; 14. Pressure detection element; 15. Vacuum pump; 16. Gas cylinder; 17. First gas pipeline; 18. Second gas pipeline; 19. Control valve; 20. Third gas pipeline; 21. Pressure reducing valve; 22. Connecting pipe; 23. End cover; 24. Sealing ring; 25. Pressing part. DETAILED DESCRIPTION

[0021] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0022] The following combination Figures 1 to 2 The low-temperature apparent thermal conductivity test device of the present invention is described.

[0023] like Figures 1 to 2 As shown, the low-temperature apparent thermal conductivity testing device provided by the embodiment of the present invention includes a regenerator shell, a refrigerator, an air charging mechanism, a heater, a first temperature detection element 2 and a second temperature detection element 3.

[0024] Specifically, the regenerator shell is used to accommodate the cold storage material to be tested. The regenerator serves as a container for the material to be tested. Other materials that need to be placed in a container for apparent thermal conductivity measurement can also be placed in the regenerator shell for measurement.

[0025] The cold head of the refrigerator is connected to the first end of the regenerator shell. The refrigerator is used to cool the regenerator shell to provide a low temperature environment for the cold storage material to be tested according to the actual temperature environment of the cold storage material to be tested in the actual refrigerator regenerator.

[0026] The charging mechanism is used to charge the gas medium into the regenerator shell to simulate the actual gas environment of the cold storage material to be tested in the regenerator of an actual refrigerator, so that the test environment of the cold storage material to be tested is consistent with its actual environment in the actual refrigerant regenerator, thereby improving the accuracy of the measurement results.

[0027] It should be noted that the filling method of the cool storage material to be tested in the regenerator shell and the pressure of the gas medium filled in the regenerator shell can be adjusted according to actual needs.

[0028] The heater includes a heating element 1 and a constant current source meter. The constant current source meter is used to output a constant current to the heating element 1, thereby generating a constant heat flow. The constant current source meter can be used to obtain the current value supplied to the heating element 1. Combined with the resistance value of the heating element 1, the heat flow value supplied to the regenerator shell can be calculated and determined.

[0029] A heating element 1 is connected to the second end of the regenerator housing and is used to heat the second end of the regenerator housing. A first temperature sensing element 2 is disposed at the first end of the regenerator housing and is used to detect the temperature of the first end of the regenerator housing. A second temperature sensing element 3 is disposed at the second end of the regenerator housing and is used to detect the temperature of the second end of the regenerator housing.

[0030] The first temperature detection element 2 and the second temperature detection element 3 may be, but are not limited to, temperature sensors.

[0031] The temperature difference across the regenerator shell can be calculated based on the detection results of the first and second temperature detection elements 2 and 3. The apparent thermal conductivity of the cold storage material can be calculated based on Fourier's law of heat conduction, combined with the length and cross-sectional area of ​​the regenerator shell.

[0032] With this setup, the apparent thermal conductivity of the cold storage material is measured and calculated using the steady-state axial heat flow method. This measurement process simulates the actual operating conditions of the cold storage material within the regenerator of a refrigerator, resulting in a more accurate and realistic determination of regenerator losses. This resolves the inaccurate determination of regenerator losses in related technologies.

[0033] It should be noted that during the measurement process, the temperature at both ends of the regenerator shell must first be lowered to a target temperature using a refrigerator and maintained stable. This target temperature can be the actual ambient temperature of the regenerator material within the refrigerator, or even a lower temperature to test the apparent thermal conductivity of the regenerator material at lower temperatures.

[0034] Then, the second end of the regenerator shell is heated by the heater. After reaching thermal equilibrium (temperature fluctuations at both ends of the regenerator shell are maintained within 0.1K within 30 minutes, thermal equilibrium is considered to be reached), the detection results of the first temperature detection element 2, the detection results of the second temperature detection element 3, and the heat flow value supplied by the heating element 1 are obtained. According to Fourier's law of heat conduction ( ,in, is the apparent thermal conductivity of the cold storage material, Q m is the heat flux value supplied by the heating element 1, L is the length of the regenerator shell, that is, the length between the two ends of the regenerator shell, A c is the cross-sectional area of ​​the regenerator shell, T h is the temperature of the second end of the regenerator shell, T c is the temperature of the first end of the regenerator shell, T h -T c is the temperature difference across the regenerator shell) for calculation.

[0035] After completing the measurement operation, the low-temperature apparent thermal conductivity test device is restored to room temperature, and the pressure of the regenerator shell and the gas storage tank 13 is restored to atmospheric pressure. The regenerator shell can be disassembled to replace the cold storage material to be tested. Repeat the above steps to continue the measurement.

[0036] It should be noted that the above-mentioned first temperature detection element 2, second temperature detection element 3 and constant current source instrument can be electrically connected to the control system, and the control system can automatically obtain the temperature of the first end of the regenerator shell detected by the first temperature detection element 2, the temperature of the second end of the regenerator shell detected by the second temperature detection element 3 and the heat flow value supplied by the heating element 1, and perform calculations based on these data.

[0037] In the embodiment of the present invention, the regenerator shell includes an outer shell and a cover plate 7 .

[0038] The housing is a cylindrical structure with one end open. The housing includes a shell 4, a first flange 5, and a second flange 6. The shell 4 is a cylindrical structure with both ends open. The first flange 5 is provided at one end of the shell 4 to close the opening at that end of the shell 4. The second flange 6 is provided at the other end of the shell 4 and serves only as a connection portion for connecting the shell to the cover plate 7. The opening at the other end of the shell 4 is open, corresponding to the open end of the shell.

[0039] The first flange 5 is connected to the cold head of the refrigerator. The first temperature detection element 2 is set on the first flange 5. The first flange 5 represents the first end of the regenerator shell. The first temperature detection element 2 can obtain the temperature of the first end of the regenerator shell by detecting the temperature of the first flange 5.

[0040] The cover plate 7 is used to seal the open end of the shell to ensure that the interior of the regenerator shell is a sealed environment. The cover plate 7 is detachably sealed to the second flange 6 to facilitate placing the cold storage material to be tested in the regenerator shell or removing the cold storage material from the regenerator shell.

[0041] The first flange 5 is made of copper, and the housing 4 is made of stainless steel. The first flange 5 and the second flange 6 are both welded to the housing 4 and fixed.

[0042] It should be noted that the wall thickness of the shell 4 needs to be designed to be as small as possible while ensuring structural strength, so as to reduce the influence of heat conduction of the regenerator shell on the measurement results of the apparent thermal conductivity of the cold storage material, reduce measurement errors, and improve the accuracy of the measurement results.

[0043] For the detachable connection between the cover plate 7 and the open end of the housing, the cover plate 7 and the second flange 6 of the housing can be fastened together using connecting bolts and nuts. The cover plate 7 can be assembled and disassembled from the housing by assembling and disassembling the connecting bolts and nuts.

[0044] The seal between the cover plate 7 and the open end of the housing can be achieved using a CF flange, or an indium wire can be placed between the cover plate 7 and the second flange 6, extending circumferentially along the open end of the housing. Indium wire has excellent ductility and plasticity. When the cover plate 7 and the second flange 6 of the housing are fastened together using connecting bolts and nuts, the cover plate 7 and the second flange 6 of the housing exert a compressive force on the indium wire. This compressive force causes the indium wire to adaptively deform, filling the gap between the cover plate 7 and the second flange 6 of the housing, thereby achieving a seal between the cover plate 7 and the second flange 6 of the housing.

[0045] The cover plate 7 represents the second end of the regenerator housing. The heater 1 is located on the side of the cover plate 7 facing away from the outer shell. The heater 1 heats the cover plate 7, thereby heating the second end of the regenerator housing. The second temperature sensing element 3 is located on the cover plate 7. By detecting the temperature of the cover plate 7, the second temperature sensing element 3 can obtain the temperature of the second end of the regenerator housing.

[0046] An inflation hole is provided on the side wall of the outer shell, and the inflation hole is used to be connected to the inflation end of the inflation mechanism so that the inflation mechanism can fill the gas medium into the regenerator shell.

[0047] In an embodiment of the present invention, the low-temperature apparent thermal conductivity testing device also includes a thermal damping plate 8, which is arranged between the first end of the regenerator shell and the cold head of the refrigerator. The thermal damping plate 8 can weaken the temperature fluctuations transmitted from the cold head of the refrigerator to the regenerator shell, and reduce the influence of the temperature fluctuations of the cold head of the refrigerator on the regenerator shell, thereby achieving more accurate data measurement.

[0048] Specifically, thermal damping sheet 8 comprises an epoxy sheet, a brass sheet, or a laminated sheet composed of glass fiber cloth and epoxy resin. The thickness of thermal damping sheet 8 is approximately 1 mm. The low thermal diffusivity of thermal damping sheet 8 effectively suppresses the impact of temperature fluctuations in the refrigerator's cold head on test data.

[0049] In an embodiment of the present invention, the low-temperature apparent thermal conductivity testing device also includes a heat insulation cover, which is arranged on the outside of the cold head of the refrigerator, the regenerator shell and the heating element 1, and is used to reduce the heat transfer between the cold head of the refrigerator and the external environment, reduce the heat transfer between the regenerator shell and the external environment, and reduce the heat transfer between the heating element 1 and the external environment, thereby reducing heat leakage.

[0050] In this embodiment, the refrigerator has a primary cold head 9 and a secondary cold head 10 . The temperature of the secondary cold head 10 is lower than that of the primary cold head 9 . The first end of the regenerator shell is connected to the secondary cold head 10 .

[0051] The heat insulation cover includes a cold screen 11, a vacuum cover 12 and a vacuum pumping mechanism. The cold screen 11 is detachably covered on the outside of the first-stage cold head 9, the second-stage cold head 10, the regenerator shell, the heating element 1, the first temperature detection element 2 and the second temperature detection element 3. The vacuum cover 12 is covered on the outside of the cold screen 11.

[0052] The vacuum cover 12 can be made of stainless steel, and the cold shield 11 can be made of copper. The outside of the cold shield 11 can also be wrapped with multiple layers of insulation material to minimize heat leakage from the outside of the cold shield 11 to the inside of the cold shield 11.

[0053] The vacuuming mechanism can perform vacuuming operation on the vacuum cover 12 and the cold shield 11, so that the pressure of the inner space of the vacuum cover 12 and the inner space of the cold shield 11 is reduced to 10 -3 Below Pa.

[0054] The cold shield 11 can reduce radiation heat transfer, and the vacuum cover 12 can reduce heat conduction and heat convection. Combining the cold shield 11 and the vacuum cover 12 can greatly reduce the heat leakage problem.

[0055] A vent is provided on the cold screen 11, and the vacuum pumping mechanism only needs to be connected to the vacuum cover 12. When the vacuum cover 12 is vacuumed by the vacuum pumping mechanism, the cold screen 11 can be vacuumed at the same time, thereby realizing the sharing of the vacuum pumping mechanism by the cold screen 11 and the vacuum cover 12, and simplifying the structure.

[0056] The above-mentioned vacuum pumping mechanism can be, but is not limited to, a molecular pump unit. Figure 1 The vacuum cover 12 is provided with a quick connection flange for connecting the vacuum cover 12 to the vacuum cover 12 .

[0057] The cold panel 11 is provided with a plurality of groups of vent holes, which are spaced apart along the axis of the cold panel 11 , and each group of vent holes is spaced apart along the circumference of the cold panel 11 .

[0058] It should be noted that, considering the need to ensure the management effect of the cold screen 11 on radiation heat transfer, the size of the vent holes on the cold screen 11 needs to be controlled. The size of the vent holes should not be too large. Generally, the diameter of the vent holes is controlled within the range of less than 5 mm, as long as the gas can pass through the vent holes smoothly.

[0059] In the embodiment of the present invention, a GM refrigerator is selected as the refrigerator, which does not require a low-temperature refrigerant, reduces maintenance costs, and improves the long-term stability and life of the system.

[0060] The GM refrigerator can achieve low temperatures through multi-stage refrigeration. Under normal circumstances, the first-stage cold head 9 can cool the temperature from room temperature to about 40K, and the second-stage cold head 10 is responsible for further cooling from about 40K to the final target temperature, such as 4.2K or lower, which can cover low-temperature operating temperature zones such as liquid nitrogen temperature zone, liquid hydrogen temperature zone and liquid helium temperature zone.

[0061] Such a configuration enables the low-temperature apparent thermal conductivity testing device provided in this embodiment to provide a wide temperature range testing platform of 4.2K~300K for the cold storage material to be tested, and can accurately test the apparent thermal conductivity of the cold storage material in the low temperature zone.

[0062] In the embodiment of the present invention, the inflation mechanism includes an air storage tank 13 , a pressure detection element 14 , a vacuum pump 15 and a gas cylinder 16 , and the air storage tank 13 , the pressure detection element 14 , the vacuum pump 15 and the gas cylinder 16 are all arranged outside the vacuum cover 12 .

[0063] The gas storage tank 13 is connected to the regenerator shell through a first gas pipeline 17 . The first gas pipeline 17 passes through the vacuum cover 12 . A sealing structure is provided between the first gas pipeline 17 and the vacuum cover 12 to ensure the sealing of the vacuum cover 12 .

[0064] The pressure sensing element 14 is mounted on the gas tank 13 and is used to detect the gas pressure within the gas tank 13. The gas tank 13 is connected to the regenerator shell via a first gas pipeline 17. The pressure within the gas tank 13 is consistent with the pressure within the regenerator shell, acting as a buffer. The pressure within the gas tank 13 detected by the pressure sensing element 14 can represent the gas pressure within the regenerator shell.

[0065] The vacuum pump 15's air extraction port is connected to the gas storage tank 13 via a second gas pipeline 18. This second gas pipeline 18 is equipped with a control valve 19, which is used to control the on / off state of the second gas pipeline 18. The control valve 19 maintains the connection state of the second gas pipeline 18, controlling the operation of the vacuum pump 15. This vacuum pump 15 can be used to evacuate the regenerator shell and gas storage tank 13, thereby reducing the pressure within these two areas. When the pressure within these areas drops to a certain level, the vacuum pump 15 can be controlled to stop, causing the control valve 19 to shut off the second gas pipeline 18.

[0066] The gas outlet of gas cylinder 16 is connected to gas storage tank 13 via third gas transmission line 20. A valve is provided at the gas outlet of gas cylinder 16 to control the opening and closing of the gas outlet. Gas cylinder 16 contains a gas medium, which may be, but is not limited to, helium or a helium-based gas mixture. A helium-based gas mixture comprises 90% to 95% helium and 5% to 10% nitrogen or hydrogen.

[0067] The valve at the gas outlet of the control gas cylinder 16 is opened, and the gas outlet of the gas cylinder 16 can be opened to fill the gas storage tank 13 and the regenerator shell with gas medium.

[0068] A pressure reducing valve 21 is provided on the third gas pipeline 20. During the charging process, the pressure reducing valve 21 regulates the gas pressure in the third gas pipeline 20 downstream of the pressure reducing valve 21. When the pressure within the regenerator shell and gas storage tank 13 reaches a certain level, the valve at the gas outlet of the gas cylinder 16 is controlled to close, thereby sealing the gas outlet of the gas cylinder 16.

[0069] In this manner, by repeatedly operating the vacuum pump 15 and the gas cylinder 16 to purge the gas reservoir 13 and the regenerator shell, the impurity content within the regenerator shell and the gas reservoir 13 can be reduced, thereby improving the purity of the gas medium. After the purge operation is complete, the gas cylinder 16 is used to fill the gas reservoir 13 and the regenerator shell with gas medium until the pressure reaches the target value.

[0070] The vacuum pump 15 may be, but is not limited to, a dry pump.

[0071] In this embodiment, the sealing structure between the first gas pipeline 17 and the vacuum cover 12 is as follows: Figure 2 The sealing structure includes a connecting pipe 22, an end cover 23, a sealing ring 24 and a pressing member 25.

[0072] The connecting pipe 22 is provided in the vacuum housing 12 , and is used for allowing the first gas pipeline 17 to enter and exit the vacuum housing 12 .

[0073] An end cap 23 is disposed on the end of the connecting tube 22 away from the vacuum housing 12 and is sealed to the connecting tube 22. A through-hole is provided on the end cap 23 for the first gas pipeline 17 to pass through. A sealing ring 24 is sleeved over the outside of the first gas pipeline 17, tightly fitting the sealing ring 24. A compression member 25 is disposed on the side of the end cap 23 away from the connecting tube 22 and is threadedly connected to the end cap 23. This compresses the sealing ring 24 against the end cap 23, ensuring that both the compression member 25 and the end cap 23 are tightly fitted to the sealing ring 24, thereby sealing the gap around the first gas pipeline 17.

[0074] Such a setting facilitates the assembly connection between the first gas pipeline 17 and the vacuum cover 12, and the sealing structure is a dynamic seal, which can allow the first gas pipeline 17 to move relative to the vacuum cover 12, and can adapt to the relative position shift of the first gas pipeline 17 and the vacuum cover 12 caused by the thermal expansion and contraction of the first gas pipeline 17, thereby reducing stress.

[0075] In the embodiment of the present invention, it is necessary to provide heat sinks for the electrical leads connected to the heating element 1 , the first temperature detection element 2 , the second temperature detection element 3 , etc., so as to reduce solid conduction heat leakage.

[0076] Specifically, the heating element 1 is connected to the constant current source instrument through the first circuit, the first end of the first circuit is connected to the constant current source instrument, and the second end of the first circuit is connected to the heating element 1, so that the first circuit can pass through the vacuum cover 12 and the cold screen 11 and then be wound around the first-level cold head 9 and the second-level cold head 10 in sequence.

[0077] Similarly, the first temperature detection element 2 is connected to the control system through the second circuit, the first end of the second circuit is connected to the first temperature detection element 2, and the second end of the second circuit is connected to the control system, so that the second circuit can pass through the vacuum cover 12 and the cold shield 11 and then be wound around the first-level cold head 9.

[0078] The second temperature detection element 3 is connected to the control system through a third line. The first end of the third line is connected to the second temperature detection element 3, and the second end of the third line is connected to the control system. The third line can pass through the vacuum cover 12 and the cold shield 11 and then be wound around the first-level cold head 9 and the second-level cold head 10 in sequence.

[0079] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A low-temperature apparent thermal conductivity testing device, characterized in that: include: A regenerator shell suitable for accommodating the cold storage material to be tested; a refrigerator, adapted to cool the regenerator shell, a cold head of the refrigerator being connected to the first end of the regenerator shell; a charging mechanism, adapted to charge gaseous medium into the regenerator shell; A heater comprising a heating element (1) and a constant current source instrument, wherein the heating element (1) is connected to the second end of the regenerator shell, the heating element (1) is suitable for heating the second end of the regenerator shell, and the constant current source instrument is suitable for outputting a constant current to the heating element (1); a first temperature detection element (2) disposed at the first end of the regenerator shell, wherein the first temperature detection element (2) is suitable for detecting the temperature of the first end of the regenerator shell; A second temperature detection element (3) is provided at the second end of the regenerator shell, and the second temperature detection element (3) is suitable for detecting the temperature of the second end of the regenerator shell.

2. The low-temperature apparent thermal conductivity testing device according to claim 1, characterized in that: The regenerator shell comprises: The shell is a cylindrical structure with one end open, and the shell includes a shell (4) with two ends open, a first flange (5) and a second flange (6), the first flange (5) closes one end opening of the shell (4), the second flange (6) is arranged at the other end of the shell (4), the first flange (5) is connected to the cold head of the refrigerator, the first temperature detection element (2) is arranged on the first flange (5), and the side wall of the shell (4) is provided with an inflation hole, and the inflation hole is suitable for being connected to the inflation end of the inflation mechanism; A cover plate (7) is adapted to close the open end of the housing, the cover plate (7) being detachably sealed to the second flange (6), the heating element (1) being arranged on a side of the cover plate (7) away from the housing, and the second temperature detection element (3) being arranged on the cover plate (7).

3. The low-temperature apparent thermal conductivity testing device according to claim 1, characterized in that: Also includes: A thermal damping plate (8) is arranged between the first end of the regenerator shell and the cold head of the refrigerator, and the thermal damping plate (8) is suitable for reducing temperature fluctuations transmitted from the cold head of the refrigerator to the regenerator shell.

4. The low-temperature apparent thermal conductivity testing device according to claim 3, characterized in that: The thermal damping sheet (8) comprises an epoxy sheet, a brass sheet, or a laminated sheet formed by combining glass fiber cloth and epoxy resin.

5. The low-temperature apparent thermal conductivity testing device according to claim 1, characterized in that: Also includes: A heat insulation cover is provided on the outside of the cold head of the refrigerator, the regenerator shell and the heating element (1), and the heat insulation cover is suitable for reducing heat transfer between the cold head of the refrigerator and the external environment, reducing heat transfer between the regenerator shell and the external environment, and reducing heat transfer between the heating element (1) and the external environment.

6. The low-temperature apparent thermal conductivity testing device according to claim 5, characterized in that: The refrigerator comprises a primary cold head (9) and a secondary cold head (10), the temperature of the secondary cold head (10) is lower than the temperature of the primary cold head (9), and the first end of the regenerator shell is connected to the secondary cold head (10); The heat shield comprises: a cold screen (11) detachably covered on the outside of the first-stage cold head (9), the second-stage cold head (10), the regenerator shell, the heating element (1), the first temperature detection element (2) and the second temperature detection element (3), and a vent hole is provided on the cold screen (11); A vacuum cover (12) is provided outside the cold screen (11); A vacuuming mechanism is suitable for performing a vacuuming operation on the vacuum cover (12) and the cold screen (11).

7. The low-temperature apparent thermal conductivity testing device according to claim 1, characterized in that: The refrigerator is a GM refrigerator.

8. The low-temperature apparent thermal conductivity testing device according to claim 6, characterized in that: The inflation mechanism comprises: a gas storage tank (13) disposed outside the vacuum cover (12), the gas storage tank (13) being connected to the regenerator shell via a first gas delivery pipeline (17), the first gas delivery pipeline (17) penetrating the vacuum cover (12), a sealing structure being provided between the first gas delivery pipeline (17) and the vacuum cover (12); A pressure detection element (14) adapted to detect the gas pressure in the gas storage tank (13); A vacuum pump (15) is arranged outside the vacuum cover (12); an air extraction port of the vacuum pump (15) is connected to the air storage tank (13) via a second air delivery pipeline (18); the second air delivery pipeline (18) is provided with a control valve (19); the control valve (19) is suitable for controlling the on-off of the second air delivery pipeline (18); A gas cylinder (16) is arranged outside the vacuum cover (12), and a gas outlet of the gas cylinder (16) is connected to the gas storage tank (13) via a third gas pipeline (20). The third gas pipeline (20) is provided with a pressure reducing valve (21), and the pressure reducing valve (21) is suitable for regulating the gas pressure in the third gas pipeline (20) located downstream of the pressure reducing valve (21).

9. The low-temperature apparent thermal conductivity testing device according to claim 8, characterized in that: The sealing structure comprises: A connecting pipe (22) is provided on the vacuum cover (12), the connecting pipe (22) being suitable for allowing the first gas pipeline (17) to enter and exit the vacuum cover (12); an end cap (23) provided at an end of the connecting pipe (22) away from the vacuum cover (12), the end cap (23) being sealedly connected to the connecting pipe (22), and the end cap (23) being provided with a through hole for the first gas transmission pipeline (17) to pass through; A sealing ring (24) is sleeved on the outside of the first gas pipeline (17), and the sealing ring (24) is tightly fitted to the first gas pipeline (17); A pressing member (25) is provided on a side of the end cover (23) away from the connecting pipe (22), the pressing member (25) is threadedly connected to the end cover (23), and the pressing member (25) is suitable for pressing the sealing ring (24) against the end cover (23).

10. The low-temperature apparent thermal conductivity testing device according to claim 6, characterized in that: The heating element (1) is connected to the constant current source instrument via a first line, a first end of the first line is connected to the constant current source instrument, the first line passes through the vacuum cover (12) and the cold screen (11), and is then wound around the first-stage cold head (9) and the second-stage cold head (10) in sequence, and a second end of the first line is connected to the heating element (1).

Images