Thermal conductivity measurement system and material comprehensive thermophysical property measurement method

Abstract

The invention relates to the technical field of thermal conductivity measurement, in particular to a thermal conductivity measurement system and a material comprehensive thermophysical property measurement method, and the thermal conductivity measurement system comprises a vacuum heat insulation bin, a sample table, a refrigeration part, a heat source part and a measurement part; the sample table, the refrigerating component, the heat source component and the measuring component are arranged in the vacuum heat insulation bin; the sample table is used for fixing a to-be-tested sample; the measuring part is used for measuring parameters of a to-be-measured sample and sending the parameters to a controller of the vacuum heat insulation bin; the refrigeration component provides a cold source for the sample table; the heat source part provides a heat source for the sample table, so that a feasible method is provided for improving the thermophysical property measurement efficiency based on the steady-state thermal conductivity measurement system, and three parameters including the thermal conductivity, the specific heat capacity and the thermal diffusion coefficient of the sample are directly identified by collecting temperature data of the transient process of the sample. The data acquisition process from deep hypothermia to normal temperature only lasts for tens of minutes, and compared with several hours or even tens of hours of a steady-state method for measuring heat conductivity and specific heat capacity, the data acquisition process is greatly improved.

Description

Technical Field

[0001] The invention relates to the technical field of thermal conductivity characteristic measurement, and in particular to a thermal conductivity measurement system and a material comprehensive thermal property measurement method. Background Art

[0002] The steady-state method is often used to measure the low-temperature thermal conductivity of materials. When using the steady-state method, the overall heat flow direction of the sample is required to be single, that is, it meets the Fourier one-dimensional thermal conductivity law. In order to build an ideal measurement environment as much as possible, vacuum insulation is often used to reduce the lateral heat flow on the sample, which requires the construction of a low-temperature vacuum environment with high requirements. In addition, maintaining a uniform and stable temperature at the cold end of the sample is also a difficulty of this method.

[0003] At the same time, in the existing scheme, the GM refrigerator is used as a cold source to measure the thermal conductivity of special-shaped samples. This facilitates the measurement work, but the processing of samples is difficult, especially the processing of non-metallic samples. There are also designs that use liquid nitrogen dewar as a cold source, and designs that add gas heat switches to the thermal conductivity measurement system, etc. Therefore, the current direction of improvement is focused on the research of low-temperature thermal conductivity measurement methods of materials, mainly focusing on temperature control, cold sources, and vacuum environments.

[0004] In actual use, the condition of the sample stage itself is also a dimension that can affect the measurement results. It has a great impact on the thermal conductivity values ​​of low thermal conductivity materials and high thermal conductivity materials, and the relationship between the true curve of nonlinear materials and the measured curve. Summary of the invention

[0005] In view of the above problems, the present invention provides a thermal conductivity measurement system and a method for measuring the comprehensive thermal properties of materials.

[0006] The technical solution adopted is a thermal conductivity measurement system, which includes a vacuum insulation chamber, a sample stage, a refrigeration component, a heat source component and a measurement component;

[0007] The sample stage, refrigeration component, heat source component and measurement component are arranged in a vacuum insulation chamber;

[0008] The sample stage is used to fix the sample to be tested;

[0009] The measuring component is used to measure the parameters of the sample to be tested and send the parameters to the controller of the vacuum insulation chamber;

[0010] The refrigeration component provides a cold source for the sample stage;

[0011] The heat source component provides a heat source to the sample stage.

[0012] Optionally, a radiation cooling shield is also included, which is arranged in the vacuum insulation chamber and covers the outside of the sample stage.

[0013] Optionally, the heat source component includes a heating resistor and a wire, wherein the heating resistor is connected to one end of the sample stage and provides a heat source, one end of the wire is connected to the heating resistor, and the other end of the wire passes through a KF interface at the bottom of the vacuum insulation chamber.

[0014] Optionally, the refrigeration components include a GM refrigerator, a primary refrigeration head, a secondary refrigeration head and a cooling connection plate;

[0015] The GM refrigerator is arranged outside the vacuum insulation chamber, the cooling end of the GM refrigerator is connected to the primary cooling head, the primary cooling head is connected to the secondary cooling head, and the cooling end of the secondary cooling head is connected to the cooling connection plate;

[0016] The cooling connection plate is connected to the other end of the sample stage and provides a cooling source.

[0017] Optionally, the measuring component includes a first temperature sensor, a second temperature sensor and a signal line;

[0018] The first temperature sensor and the second temperature sensor are both connected to the signal line signal, and the first temperature sensor and the second temperature sensor collect the temperatures of two areas of the sample;

[0019] The other end of the signal line passes through the KF interface at the bottom of the vacuum insulation chamber.

[0020] Optionally, the sample stage includes a cold plate and a hot plate, wherein the cold plate and the hot plate are respectively fixed to two ends of the sample, the cold plate is connected to a cold conducting connecting plate, and the hot plate is connected to a heating resistor.

[0021] Optionally, the sample is in a long strip structure, and the first temperature sensor and the second temperature sensor are arranged on the sample and are close to the cold plate and the hot plate respectively.

[0022] Optionally, the sample is in a pancake-shaped structure, and the cold plate and the hot plate are also in a pancake-shaped structure. The first temperature sensor is built into the cold plate and adheres to one side of the sample, and the second temperature sensor is built into the hot plate and adheres to the other side of the sample.

[0023] The present application also provides a method for measuring the comprehensive thermal properties of a material based on a thermal conductivity measurement system, comprising the following steps:

[0024] S1. Seal the vacuum insulation chamber and turn on the molecular pump set and vacuum gauge;

[0025] S2. Check whether the vacuum degree in the vacuum insulation chamber reaches the threshold;

[0026] S3. Turn on the refrigeration component. When the temperature of the cold end of the sample reaches the set temperature, the temperature data TC of the cold end of the sample and the temperature data TH of the hot end of the sample are collected by the first temperature sensor and the second temperature sensor, and transmitted to the data processor through the signal line;

[0027] S4. Turn on the heating component. When the temperature of the hot end of the sample reaches the set temperature, the temperature data TC of the cold end of the sample and the temperature data TH of the hot end of the sample are collected by the first temperature sensor and the second temperature sensor, and transmitted to the data processor through the signal line. At the same time, the output power P of the heating component is sent to the data processor;

[0028] S5. The data processor records and processes the feedback data.

[0029] Optionally, in S5, the obtained cold end temperature data TC, hot end temperature data TH and heating component output power P are identified to obtain coefficients of thermal conductivity, specific heat and thermal diffusivity coefficient function expressions, including the following sub-steps:

[0030] A1. Initialize the population and generate a certain number of individuals;

[0031] A2. Write the individual into the finite element model and solve to obtain the output;

[0032] A3. Compare the model output with the cold-end temperature data TC, the hot-end temperature data TH and the heating component output power P to obtain the fitness value;

[0033] A4. Converge the fitness value;

[0034] A5. Output thermal conductivity, specific heat, and thermal diffusivity coefficient functions.

[0035] The beneficial effects of the present invention are:

[0036] 1. A thermal conductivity measurement system including a vacuum insulation chamber, a sample stage, a refrigeration component, a heat source component and a measurement component is proposed, so that a uniform and stable temperature field is formed in the longitudinal direction of the sample; 2. A feasible method is proposed to improve the efficiency of thermal property measurement based on the steady-state thermal conductivity measurement system: by collecting the temperature data of the sample's transient process, the three parameters of the sample's thermal conductivity, specific heat capacity and thermal diffusion coefficient can be directly identified. The data collection process from deep cryogenic temperature to room temperature only takes tens of minutes, which is a significant improvement compared to the steady-state method of measuring thermal conductivity and specific heat capacity, which takes several hours or even dozens of hours. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 A schematic diagram showing the structure of a thermal conductivity measurement system;

[0038] Figure 2 A schematic diagram of a sample stage structure is shown;

[0039] Figure 3 Another schematic diagram of the sample stage structure is shown;

[0040] Figure 4Another schematic diagram of the cross-sectional structure of the sample stage is shown;

[0041] Figure 5 A thermal conductivity measurement flow chart is shown;

[0042] Figure 6 represents a flow chart of an identification process;

[0043] Figure 7 A graph showing the measurement results of thermal conductivity of single crystal copper within 57-306K;

[0044] Figure 8 Theoretical error diagram showing the thermal conductivity measurement results of single crystal copper within 57-306K;

[0045] Fig. 9 A graph showing the measurement results of thermal conductivity of polyimide;

[0046] Fig.10 Figure 2 shows the theoretical error diagram for thermal conductivity measurement of polyimide.

[0047] The accompanying drawings are marked as follows:

[0048] 1 is a vacuum insulation chamber, 2 is a radiation cooling screen, 3 is a sample stage, 4 is a secondary cooling head, 5 is a primary cooling head, 6 is a GM refrigerator, 7 is a KF25 interface, 8 is a gas valve, 9 is a cooling connection plate, 10 is a cold plate, 11 is a sample, 12 is a first temperature sensor, 13 is a second temperature sensor, 14 is a hot plate, 15 is a heating resistor, 16 is a wire, 17 is a signal line, and 18 is a fixing seat. DETAILED DESCRIPTION

[0049] The following describes the implementation of the present invention through specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific implementations, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0050] It should be noted that the illustrations provided in the following embodiments are only used to schematically illustrate the basic concept of the present invention, and thus the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0051] like Figure 1 and Figure 2As shown, a thermal conductivity measurement system includes a vacuum insulation chamber 1, a sample stage 3, a refrigeration component, a heat source component and a measurement component;

[0052] The sample stage 3, the refrigeration component, the heat source component and the measurement component are arranged in the vacuum insulation chamber 1;

[0053] The sample stage 3 is used to fix the sample to be tested;

[0054] The measuring component is used to measure the parameters of the sample to be tested and send the parameters to the controller of the vacuum insulation chamber 1;

[0055] The refrigeration component provides a cold source for the sample stage 3;

[0056] The heat source component provides a heat source to the sample stage 3 .

[0057] The purpose of this design is to propose a thermal conductivity measurement system including a vacuum insulation chamber, a sample stage, a refrigeration component, a heat source component and a measurement component, so as to form a uniform and stable temperature field in the longitudinal direction of the sample.

[0058] In this embodiment, a radiation cooling shield 2 is also included. The radiation cooling shield 2 is arranged in the vacuum insulation chamber 1 and covers the outside of the sample stage 3. The heat source component includes a heating resistor 15 and a wire 16. The heating resistor 15 is connected to one end of the sample stage 3 and provides a heat source. One end of the wire 16 is connected to the heating resistor 15, and the other end of the wire 16 passes through the KF25 interface 7 at the bottom of the vacuum insulation chamber 1.

[0059] Meanwhile, the refrigeration components include a GM refrigerator 6, a primary refrigeration head 5, a secondary refrigeration head 4 and a cooling connection plate 9;

[0060] The GM refrigerator 6 is arranged outside the vacuum insulation chamber 1, the cooling end of the GM refrigerator 6 is connected to the primary cooling head 5, the primary cooling head 5 is connected to the secondary cooling head 4, and the cooling end of the secondary cooling head 4 is connected to the cooling connection plate 9;

[0061] The cooling connection plate 9 is connected to the other end of the sample stage 3 and provides a cooling source.

[0062] Furthermore, the measuring component includes a first temperature sensor 12, a second temperature sensor 13 and a signal line 17;

[0063] The first temperature sensor 12 and the second temperature sensor 13 are both connected to the signal line 17, and the first temperature sensor 12 and the second temperature sensor 13 collect the temperatures of two areas of the sample 11;

[0064] The other end of the signal line 17 passes through the KF25 interface 7 at the bottom of the vacuum insulation chamber 1 .

[0065] Meanwhile, the sample stage 3 includes a cold plate 10 and a hot plate 14 , which are respectively fixed to two ends of the sample 11 , the cold plate 10 is connected to the cold conducting connecting plate 9 , and the hot plate 14 is connected to the heating resistor 15 .

[0066] In the specific implementation, the measurement system should form a uniform and stable temperature field in the longitudinal direction of the sample. First, build a sample stage, such as Figure 1 As shown. The sample stage is used to carry the sample and direct the heat flow to the sample. A temperature sensor is installed near both ends of the sample to measure the temperature at both ends of the effective length of the sample and calculate the temperature difference ΔT.

[0067] The sample stage is made of two metal plates, which clamp the sample in the middle and ensure good contact. The two plates provide a heat flow channel for the sample, the high temperature end is the hot plate, and the low temperature end is the cold plate. A resistor heating sheet is installed on the hot plate as the sample heat source, and the sample heat source provides a stable heating power. Under ideal conditions, the heating power is the heat flow Q.

[0068] At the same time, when making measurements, the formula based on is as follows:

[0069]

[0070] Where λ is the thermal conductivity of the material, W / m·K; Q is the heat flow from the hot end of the sample to the cold end of the sample, W; L is the effective length of the sample, that is, the distance through which the heat flow Q flows, m; A is the cross-sectional area of ​​the sample, that is, the cross-sectional area through which the heat flow Q flows, m 2 ; ΔT is the temperature difference at both ends of the effective length of the sample, K. By measuring the four physical quantities on the right side of the equal sign in the above formula, the thermal conductivity of the material at a certain temperature point can be indirectly obtained.

[0071] Furthermore, during the specific installation, when building the low-temperature vacuum environment required for measurement, the lateral heat leakage of the sample should be reduced as much as possible, so that the overall temperature field of the sample is close to the one-dimensional steady-state thermal conductivity state. A vacuum pump set, including a vacuum gauge and a stainless steel sealed warehouse body, is selected as a vacuum environment carrier, and the GM refrigerator cold head is installed at the bottom of the warehouse body. After the interfaces of each device are transferred to the interior of the warehouse body through an aviation plug, the low-temperature thermal conductivity characteristic measurement system of the material is completed.

[0072] Furthermore, in actual measurement, it is impossible to obtain an absolutely adiabatic environment, and heat leakage will always exist. This heat leakage mainly comes from three sources: conduction heat exchange between the leads of the sample accessories and the outside world, radiation heat leakage between the cold radiation shield and the sample, and heat exchange between the residual gas in the chamber and the sample. In order to eliminate the influence of heat leakage on the measurement, Q 漏 It is the heat exchange with the outside world through the above three methods, that is, the following formula:

[0073]

[0074] Among them, the conductivity measurement error is composed of four first-level errors: heat flow Q, cross-sectional area A, temperature difference ΔT and effective length L. According to the construction of the measurement system, the output power of the heating resistor is used as the heat flow Q, and the output power is calculated using the voltage U across the heating resistor and the current I passing through. The sample diameter D or the side length a of the sample is measured with a micrometer screw to calculate the cross-sectional area A. The temperature difference ΔT is calculated using the temperatures measured by the two temperature sensors. The effective length L is directly measured by the micrometer screw.

[0075] Based on the above formula, the error transfer function of thermal conductivity measurement can be written as follows. Obviously, a larger cross-sectional area A and ΔT, and smaller L and Q are required to obtain a smaller thermal conductivity measurement error.

[0076]

[0077] Based on the above formula, the following formula can be obtained from the perspective of heat flow:

[0078] Q = UI;

[0079]

[0080] From the perspective of area, the following formula can be obtained, where the cross section of the area can be circular or square:

[0081] or A=a 2 ;

[0082] Or ΔA = 2a;

[0083] From the temperature difference point of view, the following formula can be obtained:

[0084] ΔT=T H -T C ;

[0085]

[0086] The thermal conductivity measurement error sources and their values ​​can be obtained as shown in the following table:

[0087]

[0088] Therefore, measurements can be made from two perspectives, such as Figure 3 As shown, the sample 11 is a long strip structure, the first temperature sensor 12 and the second temperature sensor 13 are arranged on the sample 11 and are close to the cold plate 10 and the hot plate 14 respectively, as structure I, and the other is as shown in Figure 4As shown, the sample 11 is a round cake-shaped structure, and the cold plate 10 and the hot plate 14 are also round cake-shaped structures. The first temperature sensor 12 is built into the cold plate 10 and adheres to one side of the sample 11, and the second temperature sensor 13 is built into the hot plate 14 and adheres to the other side of the sample 11, as structure II.

[0089] In this way, the geometric dimensions of the sample stage and the sample affect the heat leakage and the sample temperature field distribution. The influence of factors such as the sample stage and the sample geometric dimensions, the sample shape and the sample stage material on the sample temperature field distribution is analyzed by ANSYS Workbench numerical calculation software. The calculation results show that the more uniform the temperature field distribution on the upper and lower surfaces of the sample, the more horizontal the isotherms around the sample surface, which means that the structure meets the measurement requirements. Then, the temperature substitution formula on the two sensors is used to calculate the thermal conductivity of the material, and the results of the thermal conductivity simulation measurement are obtained to further determine the influence of related parameters on the measurement.

[0090] After confirming the independence of the grid, the thermal conductivity simulation measurement values ​​under different parameters were obtained. The average temperature of the sensor and the sample bonding surface was selected as the temperature value of the temperature measurement point, and the following conclusions were obtained after comparing the calculation results.

[0091] (1) Although the errors of the simulation results under different temperature differences are very small, the temperature points corresponding to the measured values ​​are very different. In order to obtain coordinates as close to the true curve as possible, a smaller temperature difference should be used. The recommended temperature difference is ΔT≈10%T C .

[0092] (2) Using low thermal conductivity materials for the hot and cold plates or increasing their size will increase the surface temperature of the hot and cold plates in contact with the sample, resulting in different temperature differences under the same conditions. This will cause large errors in the simulated measurement of thermal conductivity. Therefore, under the premise of ensuring uniform distribution of the temperature field, the hot and cold plates should be processed with high thermal conductivity materials and should not be too thick.

[0093] (3) Solid samples with thermal conductivity between 0.1 W / m·K and 3 W / m·K should be made with a cross-sectional area of ​​approximately 2827.43 mm 2 , 3mm thick sample. The recommended sample sizes for materials with thermal conductivity in other ranges are shown in the table below:

[0094]

[0095]

[0096] In this embodiment, a high thermal conductivity material and a low thermal conductivity material were selected during verification, namely single crystal copper and polyimide. The single crystal copper was made into a 100mm×10mm×10mm rectangular parallelepiped sample; the polyimide was made into a 3mm×60mm cylindrical sheet sample, wherein the single crystal copper was used in structure I and the polyimide was used in structure II.

[0097] The thermal conductivity characteristics of single crystal copper in the temperature range of 57K to 306K were measured. The measurement results are shown in the curve Figure 7 The measurement results show that the λ(T) function curve of single crystal copper in the temperature range of 57K to 306K has obvious nonlinear characteristics. Substituting the measurement data into the calculation formula to obtain the theoretical relative error, as shown in Figure 8 As shown in Figure 1, the theoretical relative error is less than 2.72%. Obviously, using structure I to measure high thermal conductivity materials can achieve higher accuracy.

[0098] The thermal conductivity characteristics of polyimide in the temperature range of 230K to 258K were measured. The measurement results are shown in the curve Fig. 9 The measurement results show that the thermal conductivity of polyimide in the temperature range of 230K to 258K shows obvious linear characteristics. Similarly, the measured data is used to calculate the theoretical relative error, as shown in Fig.10 As shown in Figure 2, the theoretical relative error is less than 2.32%. Obviously, using structure II to measure low thermal conductivity materials can achieve higher accuracy.

[0099] In this way, a feasible method is proposed to improve the efficiency of thermal property measurement based on the steady-state thermal conductivity measurement system: by collecting the temperature data of the sample's transient process, the three parameters of the sample's thermal conductivity, specific heat capacity and thermal diffusion coefficient can be directly identified. The data collection process from deep cryogenic temperature to room temperature only takes tens of minutes, which is a significant improvement compared to the steady-state method of measuring thermal conductivity and specific heat capacity, which takes several hours or even dozens of hours.

[0100] In this embodiment, Figure 5 As shown, a method for measuring comprehensive thermal properties of materials is also provided, comprising the following steps:

[0101] S1. Seal the vacuum insulation chamber and turn on the molecular pump set and vacuum gauge;

[0102] S2. Check whether the vacuum degree in the vacuum insulation chamber reaches the threshold;

[0103] S3. Turn on the refrigeration component. When the temperature of the cold end of the sample reaches the set temperature, the temperature data TC of the cold end of the sample and the temperature data TH of the hot end of the sample are collected by the first temperature sensor and the second temperature sensor, and transmitted to the data processor through the signal line;

[0104] S4. Turn on the heating component. When the temperature of the hot end of the sample reaches the set temperature, the temperature data TC of the cold end of the sample and the temperature data TH of the hot end of the sample are collected by the first temperature sensor and the second temperature sensor, and transmitted to the data processor through the signal line. At the same time, the output power P of the heating component is sent to the data processor;

[0105] S5. The data processor records and processes the feedback data.

[0106] At the same time, if Figure 6 As shown, an identification process method is also provided. In S5, the obtained cold end temperature data TC, the hot end temperature data TH and the heating component output power P are identified to obtain the coefficients of the thermal conductivity, specific heat and thermal diffusivity coefficient function expression, including the following sub-steps:

[0107] A1. Initialize the population and generate a certain number of individuals;

[0108] A2. Write the individual into the finite element model and solve to obtain the output;

[0109] A3. Compare the model output with the cold-end temperature data TC, the hot-end temperature data TH and the heating component output power P to obtain the fitness value;

[0110] A4. Converge the fitness value;

[0111] A5. Output thermal conductivity, specific heat, and thermal diffusivity coefficient functions.

[0112] The purpose of this design is that the three thermophysical parameters of the material, such as thermal conductivity, specific heat capacity, and thermal diffusivity, are physical quantities that characterize the heat transfer ability of the material, and they are usually functions of temperature. The accurate value can only be obtained by actual measurement. The current measurement method faces the problems of long time consumption and low efficiency, which seriously hinders the research and development and iteration of related new materials. The parameter identification method provided in this embodiment. First, a measuring device is built and the corresponding data is collected, and then the collected data is imported into the parameter identification algorithm to obtain the thermophysical parameters of the measured object. Among them, the parameter identification algorithm uses the DBTO heuristic algorithm for iterative optimization, and uses the finite element method to establish an approximate model of the measuring device.

[0113] ANSYS APDL platform provides a complete finite element modeling and solution method, which can effectively deal with high-precision modeling and solution of complex problems. MATLAB platform provides a wealth of scientific computing tools, which can provide good computing power support for intelligent optimization algorithms. In order to establish a finite element model that is as close to the actual object as possible and expand the scope of application of this method. MATLAB software and ANSYS APDL software are used for joint simulation to realize the entire parameter identification process.

[0114] Finally, it should be noted that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A thermal conductivity measurement system, characterized in that: It comprises a vacuum insulation chamber (1), a sample table (3), a refrigeration component, a heat source component and a measurement component; The sample stage (3), the refrigeration component, the heat source component and the measurement component are arranged in the vacuum insulation chamber (1); The sample stage (3) is used to fix the sample to be tested; The measuring component is used to measure the parameters of the sample to be measured and send the parameters to the controller of the vacuum insulation chamber (1); The refrigeration component provides a cold source for the sample stage (3); The heat source component provides a heat source for the sample stage (3).

2. A thermal conductivity measurement system according to claim 1, characterized in that: It also comprises a radiation cooling shield (2), which is arranged in the vacuum insulation chamber (1) and covers the outside of the sample stage (3).

3. A thermal conductivity measurement system according to claim 1, characterized in that: The heat source component comprises a heating resistor (15) and a wire (16), wherein the heating resistor (15) is connected to one end of the sample stage (3) and provides a heat source, and one end of the wire (16) is connected to the heating resistor (15), and the other end of the wire (16) passes through a KF25 interface (7) at the bottom of the vacuum insulation chamber (1).

4. A thermal conductivity measurement system according to claim 3, characterized in that: The refrigeration components include a GM refrigerator (6), a primary refrigeration head (5), a secondary refrigeration head (4) and a cooling connection plate (9); The GM refrigerator (6) is arranged outside the vacuum insulation chamber (1), the cooling end of the GM refrigerator (6) is connected to the primary cooling head (5), the primary cooling head (5) is connected to the secondary cooling head (4), and the cooling end of the secondary cooling head (4) is connected to the cooling connection plate (9); The cooling connection plate (9) is connected to the other end of the sample stage (3) and provides a cooling source.

5. A thermal conductivity measurement system according to claim 4, characterized in that: The measuring component comprises a first temperature sensor (12), a second temperature sensor (13) and a signal line (17); The first temperature sensor (12) and the second temperature sensor (13) are both connected to the signal line (17) for signal transmission, and the first temperature sensor (12) and the second temperature sensor (13) collect temperatures of two areas of the sample (11); The other end of the signal line (17) passes through the KF25 interface (7) at the bottom of the vacuum insulation chamber (1).

6. A thermal conductivity measurement system according to claim 5, characterized in that: The sample stage (3) comprises a cold plate (10) and a hot plate (14), wherein the cold plate (10) and the hot plate (14) are respectively fixed to two ends of a sample (11), the cold plate (10) is connected to a cold-conducting connecting plate (9), and the hot plate (14) is connected to a heating resistor (15).

7. A thermal conductivity measurement system according to claim 6, characterized in that: The sample (11) is in the form of a long strip, and the first temperature sensor (12) and the second temperature sensor (13) are arranged on the sample (11) and are respectively close to the cold plate (10) and the hot plate (14).

8. A thermal conductivity measurement system according to claim 6, characterized in that: The sample (11) is in the form of a circular pancake, and the cold plate (10) and the hot plate (14) are also in the form of a circular pancake. The first temperature sensor (12) is built into the cold plate (10) and is attached to one side of the sample (11), and the second temperature sensor (13) is built into the hot plate (14) and is attached to the other side of the sample (11).

9. A method for measuring comprehensive thermal properties of materials, implemented based on a thermal conductivity measurement system according to claim 5, characterized in that: The following steps are involved: S1. Seal the vacuum insulation chamber (1) and turn on the molecular pump set and vacuum gauge; S2. Detecting whether the vacuum degree in the vacuum insulation chamber (1) reaches a threshold value; S3. Turn on the refrigeration component. When the temperature of the cold end of the sample (11) reaches the set temperature, collect the temperature data TC of the cold end of the sample (11) and the temperature data TH of the hot end of the sample (11) through the first temperature sensor (12) and the second temperature sensor (13), and transmit them to the data processor through the signal line (17); S4. Turn on the heating component. When the temperature of the hot end of the sample (11) reaches the set temperature, collect the temperature data TC of the cold end of the sample (11) and the temperature data TH of the hot end of the sample (11) through the first temperature sensor (12) and the second temperature sensor (13), and transmit them to the data processor through the signal line (17). At the same time, the output power P of the heating component is also sent to the data processor; S5. The data processor records and processes the feedback data.

10. A method for measuring comprehensive thermal properties of materials according to claim 9, characterized in that: In the above S5, the obtained cold end temperature data TC, hot end temperature data TH and heating component output power P are identified to obtain coefficients of thermal conductivity, specific heat and thermal diffusivity coefficient function expressions, including the following sub-steps: A1. Initialize the population and generate a certain number of individuals; A2. Write the individual into the finite element model and solve to obtain the output; A3. Compare the model output with the cold-end temperature data TC, the hot-end temperature data TH and the heating component output power P to obtain the fitness value; A4. Converge the fitness value; A5. Output thermal conductivity, specific heat, and thermal diffusivity coefficient functions.

Images