Dry type non-thermal source wide temperature range material heat insulation and gas release performance comprehensive measuring device

Abstract

A kind of dry heat source-free wide temperature range material heat insulation and gas release performance comprehensive measuring device, comprising: test cavity for providing the environmental condition of vacuum and heat insulation performance test, cooling system for providing cold for test cavity, vacuum system, heat insulation protection system, thermal resistance adjusting system, heat flow meter and multilayer material support cavity, the heat insulation performance and gas release performance of multilayer material can be tested by the present application, the cold boundary temperature in wide temperature range from liquid hydrogen to liquid methane is flexibly adjusted, without the input of external heating power and low-temperature fluid and can effectively heat-insulated protection is carried out to test chamber, while ensuring the accuracy of measurement, greatly simplify the complexity of system.

Description

Technical Field

[0001] This invention relates to the technology in the field of material insulation and venting performance testing, specifically a dry, heat-source-free, wide-temperature-range material insulation and venting performance comprehensive measurement device. Background Technology

[0002] High-vacuum multilayer insulation is a high-performance insulation method. Because it significantly suppresses air conduction, convection, and radiation heat transfer, its equivalent thermal coefficient can reach 10. -4 ~10 -5 With a pressure on the order of W / m·K, it is 2-3 orders of magnitude better than foam insulation and is known as super insulation. It has wide applications in industrial scenarios such as cryogenic storage and transportation, aerospace propellant storage, and the maintenance of superconducting cable insulation pipes. However, in practical engineering applications, the vacuum level of multi-layer insulation systems gradually deteriorates over time due to external leakage at various interfaces and the long-term gas release characteristics of internal metal walls, structural support materials, and heat-radiation-resistant MLI materials, leading to a decrease in insulation performance. For example, when the pressure increases from 10... -3 Pa rose to 10 - 1 In the Pa range, the heat leakage will increase by 2-3 orders of magnitude. Among the various factors that lead to a decrease in vacuum, the outgassing of the multilayer insulation material itself is the most significant. Therefore, understanding the law of change in the vacuum of the interlayer and improving the performance of multilayer insulation is a key issue that urgently needs to be addressed. Summary of the Invention

[0003] This invention addresses the shortcomings of existing technologies in testing the thermal conductivity of multilayer insulation materials at low temperatures and the inability to completely eliminate testing errors caused by external radiation. It proposes a dry, heat-source-free, wide-temperature-range material insulation and venting performance comprehensive measurement device. This device can test the insulation and venting performance of multilayer materials, enabling flexible adjustment of the cold boundary temperature across a wide temperature range from liquid hydrogen to liquid methane. It requires no external heating power or cryogenic fluid input and provides effective insulation protection for the test chamber. While ensuring measurement accuracy, it greatly simplifies the system's complexity.

[0004] This invention is achieved through the following technical solution:

[0005] This invention relates to a comprehensive measurement device for the thermal insulation and venting performance of dry, heat-source-free, wide-temperature-range materials, comprising: a test chamber for providing environmental conditions for vacuum and thermal insulation performance testing; a cooling system for providing cooling to the test chamber; a vacuum system; a thermal insulation protection system; a thermal resistance adjustment system; a heat flow meter; and a multi-layer material support cavity. Specifically: the test chamber is connected to the vacuum system to provide the required environmental conditions for testing; the cooling system is connected to the thermal resistance adjustment system to control the amount of cooling entering the heat flow meter and the thermal insulation protection system; the vacuum system is connected to the test chamber to evacuate its interior; the thermal insulation protection system is located within the test chamber and connected to the cooling system via the thermal resistance adjustment system to eliminate radiative heat transfer between the test chamber and the multi-layer material support cavity; the cold end of the thermal resistance adjustment system is connected to the cooling system, and the hot end is connected to the heat flow meter and the thermal insulation protection system to control the temperature of the hot end connector; the heat flow meter is connected at both ends to the cooling system and the multi-layer material support cavity respectively to measure the heat entering the multi-layer material support cavity from the test chamber through radiation; and the multi-layer material support cavity is connected to the heat flow meter to fix the multi-layer insulation material.

[0006] The test chamber consists of two sections, upper and lower, connected by a CF flange assembly. The upper section of the test chamber is equipped with several CF flange interfaces for the transfer of materials and the transmission of information with the outside world.

[0007] The CF flange assembly consists of a CF knife-edge flange and a high-purity oxygen-free copper gasket. The CF knife-edge flange has several bolt mounting holes. The CF knife-edge flange and the high-purity oxygen-free copper gasket are pressed together by the clamping force between the bolts and nuts to achieve a seal.

[0008] The vacuum system includes: a mechanical pump, a molecular pump, an ion pump, a mass spectrometer chamber, a test chamber evacuation valve, a low vacuum valve, a first high vacuum valve, and a second high vacuum valve. The test chamber evacuation valve is connected at one end to a CF flange interface and at the other end to the mass spectrometer chamber. The mass spectrometer chamber is connected to the mechanical pump. The mechanical pump and the molecular pump are connected via the low vacuum valve. The first high vacuum valve and the second high vacuum valve are sequentially located between the mass spectrometer chamber and the ion pump. The output end of the molecular pump is located between the first high vacuum valve and the second high vacuum valve.

[0009] The thermal resistance adjustment system includes: a first thermal switch, a second thermal switch, a first thermal switch pressure control valve, a second thermal switch pressure control valve, a pressure regulating valve, and a high-pressure helium cylinder. The first thermal switch and the second thermal switch are connected to the first thermal switch pressure control valve and the second thermal switch pressure control valve respectively through gas pipelines. The first thermal switch pressure control valve and the second thermal switch pressure control valve are connected to the pressure regulating valve. The other end of the pressure regulating valve is connected to the high-pressure helium cylinder.

[0010] The cooling system includes: a chiller head, a chiller cold head, and a chiller cold head extension flange, wherein: the chiller cold head is connected to a first thermal switch, and the chiller cold head extension flange is connected to a second thermal switch via a high thermal conductivity connecting rod.

[0011] This invention relates to a method for detecting the apparent thermal conductivity of multilayer insulation materials using the aforementioned integrated measuring device. The method involves assembling the measuring device, evacuating the vacuum, and conducting a background leakage rate test to obtain the background leakage rate. After loading the test sample, the cooling system is activated to lower the temperature. The thermal switch is then adjusted until the temperature of the insulation protection mechanism and the multilayer material support cavity are equal. Finally, the gas release performance and insulation performance of the multilayer material are tested.

[0012] The vacuuming process refers to: opening the test chamber evacuation valve, the thermal switch evacuation valve, the first thermal switch pressure control valve, and the second thermal switch pressure control valve to simultaneously evacuate the vacuum chamber and the thermal switch; then turning on the mechanical pump until the vacuum level drops to 5 Pa; then turning on the low vacuum valve and the molecular pump to further evacuate the vacuum until the vacuum level is below 1 Pa; finally, turning on the second high vacuum valve and the ion pump, and turning off the thermal switch evacuation valve, the first thermal switch pressure control valve, and the second thermal switch pressure control valve to stop evacuating the thermal switch.

[0013] The aforementioned adjustment of the thermal switch refers to: adjusting the temperature of the thermometers arranged on the surfaces of the thermal insulation protection screen and the multi-layer material support cavity until the temperatures of the two thermometers are adjusted to be equal. Specifically: taking the temperature of the multi-layer material support cavity as a reference, when the temperature of the thermal insulation protection screen is higher than the temperature of the multi-layer material support cavity, the second thermal switch pressure control valve is opened, the pressure of the pressure regulating valve is adjusted, and helium gas is introduced into the thermal switch. At this time, the thermal conductivity of the second thermal switch increases, thereby reducing the temperature of the thermal insulation protection screen. When the temperature of the thermal insulation protection screen is lower than the temperature of the multi-layer material support cavity, the first thermal switch pressure control valve is opened, and the thermal switch evacuation valve is opened to evacuate the thermal switch. At this time, the thermal conductivity of the first thermal switch decreases, thereby increasing the temperature of the thermal insulation protection screen.

[0014] The gas pressure of the thermal switch is continuously changing. After several adjustments, the temperature of the thermal insulation protection mechanism and the multi-layer material support cavity can be adjusted to be equal. When helium is introduced into the corresponding thermal switch, the temperature of the multi-layer material support cavity is reduced. When the corresponding thermal switch is evacuated, the temperature of the multi-layer material support cavity is increased.

[0015] The aforementioned test of the outgassing performance of multilayer materials refers to: periodically recording the vacuum levels collected by the low vacuum gauge and the high vacuum gauge, calculating the outgassing rate q2 = (p3-p4)V / t of the multilayer insulation material sample + background, and subtracting q2 from q1 to obtain the outgassing rate of the multilayer insulation material at the current temperature.

[0016] The aforementioned multilayer material thermal insulation performance test refers to: recording the data collected by the thermometer on the heat flow meter; fitting the temperature-position relationship of the thermometer to obtain the temperature gradient dT / dx in the vertical direction of the heat flow meter; the area S of the heat-conducting connecting rod B is known; the thermal conductivity k(T) is a function of temperature and is also a known quantity; the heat flow through the heat flow meter is q = -k(T)S·dT / dx; after obtaining the heat flow value, the apparent thermal conductivity λ of the multilayer insulation material is calculated as λ = q·ln(dT / dx). o / d i ) / 2πL e (T hot -T cold ), where: d i It is the outer diameter, L of the multi-layer material support cavity e It is the length of the multi-layered material support cavity, (T) hot -T cold ) is the temperature difference between the inner wall of the outer cylinder and the outer wall of the multi-layer material support cavity. Technical effect

[0017] This invention eliminates the need for cryogenic fluids: employing a single cryogenic refrigerator avoids the unavoidable cryogenic fluid consumption problem inherent in wet calorimetry based on evaporating cryogenic liquids, and can operate simply by plugging in electricity; it achieves wide-range temperature control without the need for heat source input for thermal compensation: by filling or evacuating the internal thermal switch, the thermal resistance between the refrigerator's cold head and the test chamber is adjusted, further controlling the test chamber temperature. Since the gas pressure of the thermal switch can be continuously adjusted from negative to positive pressure, the thermal resistance can also be continuously adjusted, thus achieving continuous temperature control; it minimizes lateral heat leakage: the sealing method using CF flanges and oxygen-free copper gaskets prevents the diffusion of external gas into the test chamber, achieving an ultra-high vacuum airtight environment; it avoids errors caused by thermal radiation and offers high measurement accuracy: the cooling capacity of the refrigerator's cold head is divided into two parts by the thermal switch and the extended flange of the refrigerator's cold head; one part is used to measure the heat leakage of multilayer materials, and the other part is used to provide cooling capacity for the insulation protection screen. By adjusting the first and second thermal switches, the insulation protection mechanism... The system is isothermal to the test chamber, eliminating errors caused by radiation; the system structure is simple: using only one refrigerator, compared to other systems that use two to three refrigerators, it greatly simplifies the system structure without sacrificing measurement accuracy; the system has a high degree of functional integration: it can test the thermal insulation and outgassing properties of materials, expanding the application scenarios of this device compared to other single-performance testing devices; a single vacuum pump unit achieves dual functions: through clever piping arrangement, the vacuum pump unit can both provide a vacuum environment for the test chamber and adjust the thermal resistance of the thermal switch, saving vacuum pump resources. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of the present invention;

[0019] Figure 2 Schematic diagram of a heat flow meter;

[0020] In the diagram: 1. Refrigerator head, 2. CF flange assembly, 3. Refrigerator cold head, 4. First thermal switch, 5. Second high thermal conductivity connecting rod, 6. Second thermal switch, 7. First high thermal conductivity connecting rod, 8. Refrigerator cold head extension flange, 9. Low thermal conductivity connecting rod, 10. Heat flow meter, 11. Upper outer cylinder, 12. Thermal insulation protection screen, 13. Multi-layer thermal insulation material, 14. Multi-layer material support cavity, 15. Vacuum chamber, 16. Lower outer cylinder, 17. First thermal switch pressure control valve, 18. Second thermal switch pressure control valve, 19. Pressure regulating valve, 20. High-pressure helium cylinder, 21. Mass spectrometer chamber, 22. Thermal switch evacuation valve, 23. Mechanical pump, 24. First high vacuum valve, 25. Low vacuum valve, 26. Molecular pump, 27. Second high vacuum valve, 28. Ion pump, 29. Gas pipeline, 30. CF flange interface, 31. Test chamber evacuation valve, 32. Low vacuum gauge, 33. High vacuum gauge, 34. Data acquisition instrument, 35. Vacuum penetration device, 36. Thermometer. Detailed Implementation

[0021] like Figure 1 As shown in this embodiment, a comprehensive measurement device for the thermal insulation and outgassing performance of a dry, heat-free, wide-temperature-range material is provided. It includes: a test chamber for providing environmental conditions for vacuum and thermal insulation performance testing; a cooling system for providing cooling capacity to the test chamber; a vacuum system; a thermal insulation protection system; a thermal resistance adjustment system; a heat flow meter 10; and a multi-layer material support cavity 14. The test chamber is connected to the vacuum system via a CF flange interface 30. A low-vacuum gauge 32 and a high-vacuum gauge 3 are connected to the upper outer cylinder 11 to measure the outgassing rate of the multi-layer thermal insulation material 13. The cooling system is connected to the thermal resistance adjustment system. The thermal insulation protection system is located within the test chamber and is connected to the cold head expansion flange 8 of the refrigerator via a low-thermal-conductivity connecting rod 9 and a second thermal switch 6. The thermal resistance adjustment system includes: a first thermal switch 4 and a second thermal switch 6 located inside the test chamber; a first thermal switch pressure control valve 17 and a second thermal switch pressure control valve 18 located outside the test chamber; a high-pressure helium cylinder 20; and a thermal switch evacuation valve 22, all connected internally and externally via gas pipelines. The heat flow meter 10 measures the heat flow from the upper outer cylinder 11 and the lower outer cylinder 16 into the multi-layer insulation material support cavity 14 through the multi-layer insulation material 13, thereby calculating the thermal conductivity of the multi-layer insulation material under the current vacuum level.

[0022] The test chamber includes: a CF flange assembly 2, an upper outer cylinder 11, a lower outer cylinder 16, and a CF flange interface 30 for transmitting materials and information inside and outside the test chamber.

[0023] The CF flange assembly 2 includes: a CF welded flange, a CF knife-edge flange, and an oxygen-free copper gasket, wherein: the flanges are connected by bolts and nuts, and a seal is formed by the clamping force between the flange and the oxygen-free copper gasket.

[0024] The upper outer cylinder 11 and the lower outer cylinder 16 are thin-walled cylindrical structures made of 304 stainless steel, with nickel plating on the inner wall to reduce radiative heat transfer with the internal environment of the test chamber. Five CF flange interfaces 30 are arranged on the upper outer cylinder 16 for the transmission of materials and information between the inside of the test chamber and the outside environment.

[0025] The five CF flange interfaces 30 are connected to the first thermal switch pressure control valve 17, the second thermal switch pressure control valve 18, the test chamber evacuation valve 31, the low vacuum gauge 32, the high vacuum gauge 33, and the thermometer 34 via CF flanges. The thermometer 34 is connected to the CF flange interfaces 30 via a vacuum penetration device 35.

[0026] The vacuum chamber penetration component 35 is equipped with 26 cores, each of which is independent and fixed by ceramic sintering, which is used to achieve information transmission inside and outside the test chamber while ensuring airtightness.

[0027] The cooling system includes: a chiller head 1 connected in sequence and a chiller cold head 3 connected via a chiller cold head extension flange 8. The chiller cold head 3 reaches the liquid hydrogen temperature zone of the test chamber. Part of the cooling energy generated flows into the multi-layer material support cavity 14 through the first thermal switch 4 for measuring the heat leakage of the multi-layer insulation material 13. The other part flows into the insulation protection mechanism through the first high thermal conductivity connecting rod 5, the second thermal switch 6 and the second high thermal conductivity connecting rod 7 to isolate the radiative heat transfer between the exposed part of the surface of the multi-layer material support cavity 14 and the upper outer cylinder 11 and the lower outer cylinder 16.

[0028] The chiller cold head 3 is the lowest temperature part of the cooling system, reaching the liquid hydrogen temperature range. It is filled with helium as the working fluid, and the chiller cold head 3 is connected to the helium pipeline by vacuum brazing.

[0029] The vacuum system is used to maintain the vacuum level within the vacuum chamber 15, preventing condensation and frost formation inside the test chamber, and providing the environmental conditions required for studying the vacuum performance of materials. The vacuum system includes: a mechanical pump 23, a molecular pump 26, and an ion pump 28 connected sequentially to the test chamber; and a low-vacuum gauge 32 and a high-vacuum gauge 33 mounted on the test chamber to monitor the vacuum level inside the vacuum chamber 15. The mechanical pump serves as a pre-stage for the molecular pump, providing the vacuum level required for its operation; the molecular pump also serves as a pre-stage for the ion pump, providing the vacuum level required for its operation. The three vacuum pumps are connected in series to form an evacuation unit, and the evacuation operation of the test chamber is controlled by opening and closing the evacuation valve 31.

[0030] The mass spectrometer chamber 21 and the ion pump 28 are respectively provided with first and second high vacuum valves 24 and 27, and the output end of the molecular pump 26 is located between the first and second high vacuum valves 24 and 27.

[0031] The vacuum degree inside the vacuum chamber 15, i.e. the total leakage rate q = (p2-p1)V / t, where: t is the test time, p1 and p2 are the pressure values ​​recorded by the vacuum gauge during this time, and V is the volume inside the vacuum chamber 15. When the multilayer insulation material 13 is not loaded, the leakage rate of the vacuum chamber 15 can be calculated according to the above formula. The difference between the total leakage rate and the leakage rate of the background is the net leakage rate of the multilayer insulation material 13.

[0032] The aforementioned thermal insulation protection system is used to isolate the radiative heat transfer between the multilayer material support cavity 14 and the exposed part of the heat flow meter 10, and the upper outer cylinder 11 and lower outer cylinder 16, thereby improving the measurement accuracy of the thermal insulation performance of the multilayer material. This thermal insulation protection system includes: a low thermal conductivity connecting rod 9, a first high thermal conductivity connecting rod 5, a second high thermal conductivity connecting rod 7, a first thermal switch 4, and a second thermal switch 6. The low thermal conductivity connecting rod 9 is connected at both ends to the cold head expansion flange 8 of the refrigerator and the thermal insulation protection screen 12, respectively, to maintain structural balance. The cooling capacity of the cold head expansion flange 8 of the refrigerator is transferred to the thermal insulation protection screen 12 through the first high thermal conductivity connecting rod 5, the second thermal switch 6, and the second high thermal conductivity connecting rod 7. The temperature of the thermal insulation protection screen 12 is adjusted by regulating the thermal resistance of the second thermal switch 6. When the temperature of the thermal insulation protection screen 12 is equal to the temperature of the multilayer material support cavity 14, the influence of external radiation on the test performance of the multilayer material can be eliminated.

[0033] The thermal resistance regulation system is used to control the temperature of the multilayer material support cavity 14 and the thermal insulation protection system. The thermal resistance regulation system includes: two thermal switches 4 and 6 respectively connected to the thermal insulation protection system and the multilayer material support cavity; a first thermal switch pressure control valve 17 and a second thermal switch pressure control valve 18 for controlling the on / off of the gas circuit of the thermal switch; a pressure regulating valve 19 for regulating the positive pressure charged into the thermal switch; and a high-pressure helium cylinder 20.

[0034] The thermal switch is a container capable of withstanding both positive and negative pressure, and its thermal conductivity is controlled by adjusting the pressure of the gas inside the container.

[0035] The high-pressure helium cylinder 20 is filled with high-pressure helium gas. Helium has a boiling point of 4.2K and is difficult to liquefy, making it suitable as a heat transfer medium for this device.

[0036] A thermal switch evacuation valve 22 for adjusting the negative pressure inside the thermal switches is provided between the two thermal switches 4 and 6 and the vacuum system.

[0037] like Figure 2 As shown, the heat flow meter 10 includes: a top flange A, a heat-conducting connecting rod B with a plurality of uniformly arranged thermometer mounting holes C, and a bottom flange D connected in sequence, wherein: a plurality of thermometers for monitoring heat flow are provided on the thermometer mounting holes C.

[0038] The aforementioned monitoring of heat flow refers to the following: because the thermal insulation system isolates the radiative heat transfer between the multi-layer material support cavity 14 and the exposed part of the heat flow meter 10 and the upper outer cylinder 11 and lower outer cylinder 16, the heat flow entering the multi-layer material support cavity 14 through the multi-layer insulation material 13 is equal to the heat flow entering the first thermal switch 4 through the heat flow meter 10. By fitting the temperature-position relationship of the thermometer, the temperature gradient dT / dx in the vertical direction of the heat flow meter is obtained. The area S of the heat-conducting connecting rod B is known, and the thermal conductivity k(T) is a function of temperature and is also a known quantity. According to Fourier's law of thermal conductivity, the heat flow through the heat flow meter is q = -k(T)·dT / dx.

[0039] Through specific practical experiments, when the mechanical pump 23, molecular pump 26, and ion pump 28 are simultaneously activated, the test chamber evacuation valve 31 is opened, and the first thermal switch is filled with 3 MPa helium gas, the vacuum degree of the vacuum chamber 15 can reach 10 MPa within one hour. -5 Pa, the temperature of the multilayer material support cavity 14 can be reduced to the liquid hydrogen temperature range (20K) within two hours.

[0040] This embodiment obtains the apparent thermal conductivity of the multilayer insulation material through the following steps:

[0041] Step 1, System Installation: First, loosen the clamping bolts on CF flange assembly 2 and remove the lower outer cylinder 16, leaving it uninsulated. Next, connect the thermometer on the heat flow meter to the external temperature measuring instrument via the vacuum perforation fitting 35. After completing the above steps, install the lower outer cylinder 16 and place a brand new oxygen-free copper gasket between the two CF flanges, forming a seal through the tightening force of the bolts.

[0042] The second step is system evacuation: Before evacuation, ensure that the second high-vacuum valve 27, low-vacuum valve 25, and test chamber evacuation valve 31 are closed. The evacuation process is as follows: First, open the test chamber evacuation valve 31, thermal switch evacuation valve 22, first thermal switch pressure control valve 17, and second thermal switch pressure control valve 18 to simultaneously evacuate the vacuum chamber and thermal switch, preventing condensation and frost buildup inside. Next, turn on the mechanical pump 23. When the system vacuum level drops to approximately 5 Pa, turn on the low-vacuum valve 25 and molecular pump 26 to further evacuate the system. When the system vacuum level is below 1 Pa, open the second high-vacuum valve 27 and turn on the ion pump 28. Finally, close the thermal switch evacuation valve 22, first thermal switch pressure control valve 17, and second thermal switch pressure control valve 18 to stop evacuating the thermal switch.

[0043] The third step is to test the background leakage rate: First, the leakage rate of the test chamber itself is tested. After closing the evacuation valve 31 of the test chamber, the vacuum levels collected by the low vacuum gauge 32 and the high vacuum gauge 33 are recorded periodically, and then the background leakage rate is calculated. Where p1 is the vacuum level at the initial moment and p2 is the vacuum level at the final moment.

[0044] Step 4, loading the test sample: First, disconnect the test chamber evacuation valve 31 from the upper outer cylinder 11, so that the vacuum chamber 15 is in an atmospheric environment. Then, open the clamping bolts on the CF flange assembly 2, remove the lower outer cylinder 16, wrap multiple layers of insulation material on the multi-layer material support cavity 14, and fix the multi-layer insulation material with thin thread. Then, install the lower outer cylinder 16, and place a brand new oxygen-free copper gasket between the two CF flanges. A seal is formed by the tightening force of the bolts.

[0045] Fifth step, start the cooling system: wait for the vacuum level in the test chamber to drop below 1 Pa, start the cooling system, wait for the multi-layer material support cavity 14 to cool down, and when the thermometer at the secondary cold head 4 is monitored to be in the liquid hydrogen temperature zone, the next step can be carried out.

[0046] Step 6: Adjusting the thermal switch: The adjustment of the thermal switch is based on the temperatures of the thermometers 36 arranged on the surfaces of the thermal insulation protection screen 12 and the multilayer material support cavity 14. The goal is to adjust the temperatures of the two thermometers to be equal. The method is as follows: Using the temperature of the multilayer material support cavity 14 as a reference, when the temperature of the thermal insulation protection screen 12 is higher than that of the multilayer material support cavity 14, the second thermal switch pressure control valve 18 is opened, and the pressure of the pressure regulating valve 19 is adjusted to introduce helium gas into the thermal switch. At this time, the thermal conductivity of the second thermal switch increases, thereby reducing the temperature of the thermal insulation protection screen 12. When the temperature of the thermal insulation protection screen 12 is lower than that of the multilayer material support cavity 14, the first thermal switch pressure control valve 17 is opened, and the thermal switch evacuation valve 22 is opened to evacuate the thermal switch. At this time, the thermal conductivity of the first thermal switch decreases, thereby increasing the temperature of the thermal insulation protection screen 12. The gas pressure of the thermal switch changes continuously, and after several adjustments, the temperatures of the thermal insulation protection mechanism and the multilayer material support cavity can be adjusted to be equal. To lower the temperature of the multilayer material support cavity, similar to the steps described above, helium gas is introduced into the corresponding thermal switch. To raise the temperature of the multilayer material support cavity, the corresponding thermal switch is evacuated. Thus, through the coupling of the refrigerator and the thermal switch, a wide range of temperature regulation of the multilayer material support cavity, from the liquid hydrogen temperature range to the liquid methane temperature range, can be achieved without a heat source.

[0047] Step 7, outgassing performance test of multilayer material: After obtaining the background leakage rate in step 3, repeat the operation of step 3, periodically record the vacuum degree collected by low vacuum gauge 32 and high vacuum gauge 33, and calculate the outgassing rate of multilayer insulation material sample + background q2=(p3-p4)V / t. Subtracting q2 from q1 can give the outgassing rate of multilayer insulation material at the current temperature, where: p1 is the vacuum degree at the initial moment and p2 is the vacuum degree at the final moment.

[0048] Step 8, Multilayer Material Thermal Insulation Performance Test: Record the data collected by the thermometer on the heat flow meter. By fitting the temperature-position relationship of the thermometer, obtain the temperature gradient dT / dx in the vertical direction of the heat flow meter. The area S of the heat-conducting connecting rod B is known, and the thermal conductivity k(T) is a function of temperature and is also a known quantity. The heat flow through the heat flow meter is q=-k(T)S·dT / dx. After obtaining the heat flow value, calculate the apparent thermal conductivity λ=q·ln(dT / dx) of the multilayer insulation material. o / d i ) / 2πL e (T hot -T cold ), where: d i It is the outer diameter, L of the multi-layer material support cavity e It is the length of the multi-layered material support cavity, (T) hot -T cold ) is the temperature difference between the inner wall of the outer cylinder and the outer wall of the multi-layer material support cavity.

[0049] Compared with existing technologies, this device achieves continuous adjustment of the thermal resistance of the thermal switch by filling the container with high-pressure helium or drawing a vacuum, and further achieves continuous temperature control from the liquid hydrogen temperature range to the liquid methane temperature range without a heat source; it also decomposes the cooling capacity of the refrigeration system into two parts, and completely eliminates the influence of external radiation on the material insulation performance test by adjusting the thermal switch, and features a wide temperature range, high precision and safe operation.

[0050] The above-described specific implementations can be partially adjusted by those skilled in the art in different ways without departing from the principles and purpose of the present invention. The scope of protection of the present invention is defined by the claims and is not limited to the above-described specific implementations. All implementation schemes within the scope of the claims are bound by the present invention.

Claims

1. A comprehensive measurement device for the thermal insulation and venting performance of dry, heat-source-free, wide-temperature-range materials, characterized in that, include: The test chamber provides the environmental conditions for vacuum and thermal insulation performance testing; a cooling system provides cooling to the test chamber; a vacuum system; a thermal insulation protection system; a thermal resistance adjustment system; a heat flow meter; and a multilayer material support cavity. Specifically: the test chamber is connected to the vacuum system to provide the necessary environmental conditions for testing; the cooling system is connected to the thermal resistance adjustment system to control the amount of cooling entering the heat flow meter and thermal insulation protection system; the vacuum system is connected to the test chamber to evacuate its interior; the thermal insulation protection system is located within the test chamber and connected to the cooling system via the thermal resistance adjustment system to eliminate radiative heat transfer between the test chamber and the multilayer material support cavity; the cold end of the thermal resistance adjustment system is connected to the cooling system, and the hot end is connected to the heat flow meter and the thermal insulation protection system to control the temperature of the hot end connectors; the heat flow meter is connected at both ends to the cooling system and the multilayer material support cavity to measure the heat entering the multilayer material support cavity through radiation from the test chamber; and the multilayer material support cavity is connected to the heat flow meter to fix the multilayer insulation material. The thermal resistance adjustment system includes: a first thermal switch, a second thermal switch, a first thermal switch pressure control valve, a second thermal switch pressure control valve, a pressure regulating valve, and a high-pressure helium cylinder. The first thermal switch and the second thermal switch are connected to the first thermal switch pressure control valve and the second thermal switch pressure control valve respectively through gas pipelines. The first thermal switch pressure control valve and the second thermal switch pressure control valve are connected to the pressure regulating valve. The other end of the pressure regulating valve is connected to the high-pressure helium cylinder. The cooling system includes: a chiller head connected in sequence and a chiller cold head connected via a chiller cold head extension flange, wherein: the chiller cold head reaches the liquid hydrogen temperature zone of the test chamber, and part of the cooling energy generated flows into the multi-layer material support cavity through the first thermal switch for measuring the heat leakage of the multi-layer insulation material; the other part flows into the insulation protection screen through the first high thermal conductivity connecting rod, the second thermal switch and the second high thermal conductivity connecting rod for isolating the exposed part of the surface of the multi-layer material support cavity from the radiative heat transfer between the upper outer cylinder and the lower outer cylinder.

2. The comprehensive measurement device for the insulation and venting performance of dry, heat-source-free, wide-temperature-range materials according to claim 1, characterized in that, The test chamber consists of two sections, upper and lower, connected by a CF flange assembly. The upper section of the test chamber is equipped with several CF flange interfaces for the transfer of materials and the transmission of information with the outside world.

3. The comprehensive measuring device for the thermal insulation and venting performance of dry, heat-source-free, wide-temperature-range materials according to claim 2, is characterized in that... The CF flange assembly consists of a CF knife-edge flange and a high-purity oxygen-free copper gasket. The CF knife-edge flange has several bolt mounting holes. The CF knife-edge flange and the high-purity oxygen-free copper gasket are pressed together by the clamping force between the bolts and nuts to achieve a seal.

4. The comprehensive measuring device for the insulation and venting performance of dry, heat-source-free, wide-temperature-range materials according to claim 2, is characterized in that, The vacuum system includes: a mechanical pump, a molecular pump, an ion pump, a mass spectrometer chamber, a test chamber evacuation valve, a low vacuum valve, a first high vacuum valve, and a second high vacuum valve. The test chamber evacuation valve is connected at one end to a CF flange interface and at the other end to the mass spectrometer chamber. The mass spectrometer chamber is connected to the mechanical pump. The mechanical pump and the molecular pump are connected via the low vacuum valve. The first high vacuum valve and the second high vacuum valve are sequentially located between the mass spectrometer chamber and the ion pump. The output end of the molecular pump is located between the first high vacuum valve and the second high vacuum valve.

5. A method for detecting the apparent thermal conductivity of a multilayer insulation material using a comprehensive measuring device according to any one of claims 1-4, comprising: assembling the measuring device, evacuating the vacuum, and performing a background leakage rate test to obtain the background leakage rate; then loading the test sample, cooling the sample by starting the cooling system, and adjusting the thermal switch until the temperature of the insulation protection screen and the multilayer material support cavity are equal; finally, performing a multilayer material gas release performance test and a multilayer material insulation performance test.

6. The method for detecting apparent thermal conductivity according to claim 5, characterized in that, The vacuuming process refers to: opening the test chamber evacuation valve, the thermal switch evacuation valve, the first thermal switch pressure control valve, and the second thermal switch pressure control valve to simultaneously evacuate the vacuum chamber and the thermal switch; then turning on the mechanical pump until the vacuum level drops to 5 Pa; then turning on the low vacuum valve and the molecular pump to further evacuate the vacuum until the vacuum level is below 1 Pa; finally, turning on the second high vacuum valve and the ion pump, and turning off the thermal switch evacuation valve, the first thermal switch pressure control valve, and the second thermal switch pressure control valve to stop evacuating the thermal switch.

7. The method for detecting apparent thermal conductivity according to claim 5, characterized in that, The aforementioned adjustment of the thermal switch refers to: adjusting the temperature of the thermometers arranged on the surfaces of the thermal insulation protection screen and the multi-layer material support cavity until the temperatures of the two thermometers are adjusted to be equal. Specifically, taking the temperature of the multi-layer material support cavity as a reference, when the temperature of the thermal insulation protection screen is higher than the temperature of the multi-layer material support cavity, the second thermal switch pressure control valve is opened, the pressure of the pressure regulating valve is adjusted, and helium gas is introduced into the thermal switch. At this time, the thermal conductivity of the second thermal switch increases, thereby reducing the temperature of the thermal insulation protection screen. When the temperature of the thermal insulation protection screen is lower than the temperature of the multi-layer material support cavity, the first thermal switch pressure control valve is opened, and the thermal switch evacuation valve is opened to evacuate the thermal switch. At this time, the thermal conductivity of the first thermal switch decreases, thereby increasing the temperature of the thermal insulation protection screen. The gas pressure of the thermal switch is continuously variable, and the temperature of the thermal insulation protection screen and the multi-layer material support cavity can be adjusted to be equal after several adjustments.

8. The method for detecting apparent thermal conductivity according to claim 5, characterized in that, The aforementioned test of the outgassing performance of multilayer materials refers to periodically recording the vacuum levels collected by the low-vacuum gauge and the high-vacuum gauge, and calculating the outgassing rate of the multilayer insulation material sample plus the background. The aforementioned multilayer material thermal insulation performance test refers to: recording the data collected by the thermometer on the heat flow meter, and obtaining the temperature gradient in the vertical direction of the heat flow meter by fitting the relationship between the temperature and position of the thermometer. The area of ​​heat-conducting link B Given thermal conductivity It is a function of temperature and is also a known quantity. The heat flow through the heat flow meter is... After obtaining the heat flow value, the apparent thermal conductivity of the multilayer insulation material is calculated.

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