Automatic heat conductivity coefficient measuring device and method

Abstract

The invention discloses an automatic heat conductivity coefficient measuring device and method, and relates to the field of material heat conduction performance testing, and the device comprises a sample support, a heating module, a sample disc, a heat dissipation module, a stabilized voltage supply, a thermometer and a computer; the heating module comprises heat insulation ceramic, a ceramic heating sheet and a heating disc which are in close contact and is used for transmitting heat to the sample disc; the heat dissipation module is used for dissipating heat of the sample disc; the stabilized voltage supply is used for heating the heating sheet; the thermometers are used for measuring temperature change data and corresponding time of the upper ends and the lower ends of the heating disc, the heat dissipation disc and the sample disc respectively, and the computer is used for obtaining the temperature change data and the corresponding time from the thermometers and determining a temperature and time change curve. The heat dissipation rate of the heat dissipation disc is fitted by adopting a polynomial fitting method, the heat conductivity coefficient of the sample disc is determined, and accurate acquisition of the heat conductivity coefficient is realized.

Description

Technical Field

[0001] The invention relates to the field of material thermal conductivity testing, and in particular to an automatic thermal conductivity measuring device and method. Background Art

[0002] Thermal conductivity is the amount of heat transferred by a unit temperature gradient through a unit heat conduction surface in a unit time, and is an important parameter that characterizes the thermal conductivity of a material. Conceptually, thermal conductivity represents the efficiency of heat propagation within a material. The higher the thermal conductivity, the less heat loss within the material, and the better the thermal conductivity. On the contrary, the lower the thermal conductivity, the worse the thermal conductivity of the material. And thermal conductivity is widely used in many fields. In the construction industry, thermal conductivity is used to evaluate the thermal insulation performance of materials. The lower the thermal conductivity, the better the thermal insulation effect of the material. In electronic equipment design, thermal conductivity is used to evaluate the performance of heat dissipation materials. The higher the thermal conductivity, the better the heat dissipation effect. In the process of energy transmission and utilization, thermal conductivity has a great influence on system efficiency. Improving thermal conductivity can improve energy utilization efficiency.

[0003] In the process of material research, thermal conductivity is one of the important indicators for evaluating material performance. The steady-state method provides a reliable means of measurement and is a common method for measuring thermal conductivity. At present, there are steady-state thermal conductivity measuring instruments used in scientific research and teaching, but the existing experimental devices have a long measurement process. More importantly, the device needs to take separate operation steps when measuring multiple parameters. This process is cumbersome and error-prone, which increases the risk of data errors and affects the accuracy of data acquisition. In addition, the existing device lacks the function of intuitively displaying process data, which means that during the experiment, the operator cannot immediately obtain the changing trend and real-time status of key parameters, making it difficult to accurately capture and use process data in the thermal conductivity calculation process, which greatly hinders the accurate acquisition of thermal conductivity. Summary of the invention

[0004] The present invention provides an automatic thermal conductivity measuring device and method, which are used to solve the above-mentioned problem existing in the prior art, that is, how to improve the accuracy of obtaining thermal conductivity in the prior art. The present invention provides an automatic thermal conductivity measuring device, which includes:

[0005] It includes a sample holder, a heating module, a sample tray, a heat dissipation module, a voltage-stabilized power supply, a thermometer and a computer;

[0006] The heating module comprises a heat-insulating ceramic, a ceramic heating plate and a heating plate which are sequentially mounted on the sample holder from top to bottom; wherein the voltage-stabilized power supply is electrically connected to the ceramic heating plate, and the ceramic heating plate is heated by the voltage-stabilized power supply;

[0007] The heat dissipation module comprises a heat dissipation plate and a radiator placed sequentially from top to bottom;

[0008] During heating, the sample tray of the heating module and the heat dissipation module are placed together from top to bottom until the temperature of the heating tray and the heat dissipation tray reaches a steady state, then the heating tray is directly contacted with the heat dissipation tray to make the temperature of the heat dissipation tray reach a preset temperature, and then the sample tray is placed back between the heating tray and the heat dissipation tray;

[0009] The thermometer is a digital high-precision four-channel thermometer, which is used to detect the side of the heating plate, between the heating plate and the upper surface of the sample plate, between the lower surface of the sample plate and the heat sink, and the side of the heat sink, and respectively measure the temperature change data of the heating plate, the heat sink, and the upper and lower ends of the sample plate and the corresponding time;

[0010] The computer is used to obtain temperature change data and corresponding time from a thermometer, determine the temperature and time change curve, determine the heat dissipation of the heat dissipation disk by using a polynomial fitting method to measure the heat dissipation rate of the heat dissipation disk, and obtain the thermal conductivity of the sample disk when the temperatures of the heating disk and the heat dissipation disk reach a steady state and the heat transferred from the heating disk to the sample disk is equal to the heat dissipation of the heat dissipation disk.

[0011] Optionally, the sample holder includes a first acrylic plate, a second acrylic plate, a third acrylic plate, a butterfly screw and a screw rod.

[0012] Optionally, the regulated power supply is an adjustable DC regulated power supply.

[0013] Optionally, the sample plate, heating plate and heat dissipation plate are all in the shape of discs with a certain thickness; wherein the diameter range of the sample plate, heating plate and heat dissipation plate is selected from 60 to 130 mm, and the thickness range is selected from 5 to 10 mm.

[0014] Optionally, the heating plate and the heat dissipation plate are made of copper.

[0015] Optionally, the heat sink includes a semiconductor cooling fin and a fan.

[0016] The present invention provides an automatic thermal conductivity measurement method, characterized by comprising:

[0017] Assemble and fix the automatic thermal conductivity measuring device through the sample holder so that the ceramic heating plate, the heating plate, the sample plate and the heat dissipation plate are in close contact;

[0018] The ceramic heating plate is heated by a voltage-stabilized power supply, and the ceramic heating plate is in direct contact with the heating plate, so that the heat is transferred from the heating plate to the heat dissipation plate from top to bottom through the sample plate. At the same time, the temperature of the heating plate, the heat dissipation plate and the upper and lower ends of the sample plate is measured by a thermometer until the temperature of the heating plate and the heat dissipation plate reaches a steady state; the thermometer is a digital high-precision four-channel thermometer;

[0019] When the temperatures of the heating plate and the heat dissipation plate reach a steady state, the heating plate is directly contacted with the heat dissipation plate; when the temperature of the heat dissipation plate is heated to a preset temperature, the sample plate is directly placed on the heat dissipation plate, and the collected temperature of the heat dissipation plate and the corresponding time are transmitted to the computer through a thermometer to obtain a temperature and time variation curve;

[0020] According to the temperature and time variation curve, the heat passing through the sample disk and the heat dissipation rate of the heat dissipation disk are obtained. The heat dissipation rate of the heat dissipation disk is fitted by a polynomial fitting method to determine the heat dissipation of the heat dissipation disk. When the temperatures of the heating disk and the heat dissipation disk reach a steady state, the heat transferred from the heating disk to the sample disk is equal to the heat dissipation of the heat dissipation disk, and the thermal conductivity of the sample disk is obtained.

[0021] Optionally, when the temperatures of the heating disk and the heat dissipation disk reach a steady state, the heat transferred from the heating disk to the sample disk is equal to the heat dissipation of the heat dissipation disk, and the thermal conductivity of the sample disk is obtained, specifically including:

[0022] The areas of the upper and lower ends are both A. According to Fourier's law, the heat passing through the sample plate in time t is obtained using the following formula:

[0023]

[0024] Among them, T 1 , T 2 are the upper and lower temperatures of the sample plate when reaching steady state, h is the thickness of the heat sink, A is the upper and lower areas of the heat sink and sample plate, and k is the thermal conductivity of the sample plate;

[0025] When the heat transfer reaches a steady state, the temperature of the upper and lower surfaces of the sample plate is T 1 and T 2 The heat flux transferred from the heating plate to the sample plate is equal to the heat dissipation from the heat sink to the surrounding environment. 2 The heat dissipation rate at that time is calculated by the following formula to obtain the heat flux of the heat sink:

[0026]

[0027] Wherein, m is the mass of the heat sink, c is the specific heat capacity of the heat sink;

[0028] Then, the thermal conductivity of the sample disk is obtained using the following formula:

[0029]

[0030] Where R is the radius of the heat sink.

[0031] Optionally, measuring the temperatures of the upper and lower ends of the heating plate, the heat dissipation plate, and the sample plate by a thermometer specifically includes:

[0032] Place the K-type thermocouple measuring heads on the side of the heating plate, between the heating plate and the upper surface of the sample plate, between the lower surface of the sample plate and the heat sink, and on the side of the heat sink. Insert the other end into the four corresponding channels of the digital high-precision four-channel thermometer to measure the temperatures of the heating plate, heat sink, and upper and lower ends of the sample plate.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention provides an automatic thermal conductivity measurement device and method, the device heats the ceramic heating plate through a voltage-stabilized power supply, the ceramic heating plate is in direct contact with the heating disk, and the heat can be transferred to the sample disk through the ceramic heating plate, and then the heat is transferred from the heating disk to the heat dissipation disk through the sample disk; a digital high-precision four-channel thermometer is used to collect temperature change data of the heating disk, the upper and lower surfaces of the sample disk and the heat dissipation disk, and the collected data and the corresponding time are transmitted to a computer, thereby realizing intuitive display and recording of the temperature and time of the measurement process, and finally fitting the heat dissipation rate of the heat dissipation disk according to the recorded data. Since at steady-state temperature, the heat transferred from the heating disk to the sample disk is equal to the heat dissipation of the heat dissipation disk, the thermal conductivity of the sample disk can be determined, and then the thermal conductivity can be accurately obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0035] Figure 1 A structural diagram of a support for an automatic thermal conductivity measuring device provided by an embodiment of the present invention;

[0036] Figure 2 A working diagram of an automatic thermal conductivity measuring device provided by an embodiment of the present invention;

[0037] Figure 3 The experimental values ​​and fitting curves of the temperature changes over time of the six groups of heat dissipation disks provided in the embodiment of the present invention.

[0038] In the figure: 1. first acrylic plate; 2. second acrylic plate; 3. third acrylic plate; 4. thermal insulation ceramic; 5. ceramic heating plate; 6. heating plate; 7. sample plate; 8. heat dissipation plate; 9. radiator; 10. butterfly screw; 11. screw. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings in the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] The technical solution of the present invention and how the technical solution of the present invention solves the above-mentioned technical problems are described in detail below with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. The embodiments of the present invention will be described below in conjunction with the accompanying drawings.

[0041] Example

[0042] Figure 1 is a structural diagram of a support for an automatic thermal conductivity measuring device provided by an embodiment of the present invention, such as Figure 1 As shown, an automatic thermal conductivity measuring device shown in this embodiment includes a sample holder, a heating module, a sample tray, a heat dissipation module, a voltage-stabilized power supply, a thermometer and a computer;

[0043] The heating module comprises a heat-insulating ceramic 4, a ceramic heating plate 5 and a heating plate 6 which are sequentially mounted on the sample holder from top to bottom; wherein the voltage-stabilized power supply is electrically connected to the ceramic heating plate 5, and the ceramic heating plate 5 is heated by the voltage-stabilized power supply;

[0044] The heat dissipation module comprises a heat dissipation plate 8 and a heat sink 9 placed sequentially from top to bottom;

[0045] During heating, the heating module sample tray and the heat dissipation module are placed together from top to bottom until the temperature of the heating tray 6 and the heat dissipation tray 8 reaches a steady state, and then the heating tray 6 is directly contacted with the heat dissipation tray 8 to make the temperature of the heat dissipation tray 8 reach a preset temperature, and then the sample tray 7 is placed back between the heating tray 6 and the heat dissipation tray 8;

[0046] The thermometer is a digital high-precision four-channel thermometer, which is used to detect the side of the heating plate, between the heating plate and the upper surface of the sample plate, between the lower surface of the sample plate and the heat sink, and the side of the heat sink, and respectively measure the temperature change data of the upper and lower ends of the heating plate 6, the heat sink 8, and the sample plate 7 and the corresponding time;

[0047] The computer is used to obtain temperature change data and corresponding time from the thermometer, determine the temperature and time change curve, determine the heat dissipation of the heat dissipation disk 8 by using a polynomial fitting method for the heat dissipation rate, and obtain the thermal conductivity of the sample disk 7 when the temperatures of the heating disk and the heat dissipation disk reach a steady state and the heat transferred from the heating disk to the sample disk is equal to the heat dissipation of the heat dissipation disk.

[0048] Optionally, the sample holder includes a first acrylic plate 1 , a second acrylic plate 2 , a third acrylic plate 3 , a butterfly screw 10 and a screw rod 11 .

[0049] Exemplarily, the voltage-stabilized power supply is an adjustable DC voltage-stabilized power supply; the insulating ceramic sheet, the heating ceramic sheet, the heating plate 6, the sample plate 7, the heat dissipation plate 8 and the radiator are placed in the sample holder from top to bottom in sequence, and the K-type thermocouple measuring head is placed on the side of the heating plate 6, between the heating plate 6 and the upper surface of the sample plate 7, between the lower surface of the sample plate 7 and the heat dissipation plate 8, and on the side of the heat dissipation plate 8, and the other end is inserted into the four channels corresponding to the digital high-precision four-channel thermometer, and fixed with butterfly screws 10 so that the heating plate 6, the sample plate 7 and the heat dissipation plate 8 are in full contact; the digital high-precision four-channel thermometer is connected to the computer; the positive and negative poles of the heating ceramic sheet are connected to the voltage-stabilized DC power supply, and the radiator is fixed to the sample holder.

[0050] Optionally, the sample plate 7, the heating plate 6 and the heat dissipation plate 8 are all in the shape of round sheets with a certain thickness.

[0051] Exemplarily, the diameter range of the sample plate, the heating plate and the heat dissipation plate may be, for example, 60 to 130 mm, and the thickness range may be 5 to 10 mm.

[0052] Generally, semiconductor radiators are usually used for cooling mobile phones. When heat dissipation is required, the device can select a semiconductor radiator for heat dissipation, wherein the semiconductor radiator includes a semiconductor cooling sheet, a heat sink and a fan.

[0053] Optionally, the heating plate 6 and the heat dissipation plate 8 are made of copper.

[0054] Optionally, the heat sink 9 includes a semiconductor cooling sheet and a fan.

[0055] An automated thermal conductivity measurement method, such as Figure 2 As shown, the following steps are included:

[0056] S1: Assemble and fix the automatic thermal conductivity measuring device through the sample holder so that the ceramic heating plate, heating plate, sample plate and heat dissipation plate are in close contact.

[0057] S2: The ceramic heating plate is heated by a regulated power supply. The ceramic heating plate is in direct contact with the heating plate, so that heat is transferred from the heating plate to the heat dissipation plate through the sample plate from top to bottom. At the same time, the temperature of the heating plate, the heat dissipation plate and the upper and lower ends of the sample plate is measured by a thermometer until the temperature of the heating plate and the heat dissipation plate reaches a steady state.

[0058] Optionally, the thermometer is a digital high-precision four-channel thermometer.

[0059] Optionally, place the K-type thermocouple measuring head on the side of the heating plate, between the heating plate and the upper surface of the sample plate, between the lower surface of the sample plate and the heat sink, and on the side of the heat sink, and insert the other end into the four channels corresponding to the digital high-precision four-channel thermometer to measure the temperatures of the heating plate, the heat sink, and the upper and lower ends of the sample plate.

[0060] S3: When the temperatures of the heating plate and the heat sink reach a steady state, the heating plate is directly contacted with the heat sink; when the temperature of the heat sink is heated to a preset temperature, the sample plate is directly placed on the heat sink, and the collected temperature of the heat sink and the corresponding time are transmitted to the computer through a thermometer to obtain a temperature and time change curve.

[0061] For example, when the temperature of the heat sink is heated to about 25° C. higher than the steady-state temperature, the sample plate can be directly placed on the heat sink, and the temperature of the heat sink can be obtained by a digital high-precision four-channel thermometer.

[0062] Generally, the area of ​​the side of the sample pan is much smaller than the area of ​​its upper and lower surfaces. It can be considered that heat is only transferred in the vertical direction, and the heat dissipated from the side is negligible. Therefore, a temperature gradient in the vertical direction is formed in the sample pan.

[0063] S4: According to the temperature and time variation curve, the heat passing through the sample plate and the heat dissipation rate of the heat dissipation plate are obtained, and the heat dissipation rate of the heat dissipation plate is fitted by a polynomial fitting method to determine the heat dissipation of the heat dissipation plate. When the temperatures of the heating plate and the heat dissipation plate reach a steady state, the heat transferred from the heating plate to the sample plate is equal to the heat dissipation of the heat dissipation plate, and the thermal conductivity of the sample plate is obtained.

[0064] Exemplarily, by performing a second-order fitting on the data of the measured heat dissipation rate, 6 sets of data graphs are obtained, such as Figure 3 As shown, it can be seen that the second-order fitting result curve is closer to the experimental value curve, and the heat dissipation curve obtained by the semiconductor heat sink is closer to the natural cooling curve.

[0065] Optionally, when the steady-state temperature is reached, the temperatures at the top and bottom of the sample tray are T 1 , T 2, the thickness of the sample plate and the heat sink is h, and the upper and lower areas of both are A. According to Fourier's law, the heat Q passing through the sample plate in time t is obtained using the following formula:

[0066]

[0067] Where k is the thermal conductivity of the sample disk.

[0068] Optionally, the sample plate, the heating plate and the heat dissipation plate are all in the shape of round sheets with a certain thickness.

[0069] For example, the diameter of the sample plate, the heating plate and the heat dissipation plate may range from 60 to 130 mm, and the thickness may range from 5 to 10 mm.

[0070] The sample pan area is obtained using the following formula:

[0071] A=πR 2 ,

[0072] Where R is the radius of the sample disk.

[0073] According to the steady-state temperature T 2 The heat dissipation rate at that time is used to obtain the heat flow. The specific calculation formula is as follows:

[0074]

[0075] Where m is the mass of the heat sink and c is the specific heat capacity of the heat sink.

[0076] When the heat transfer reaches a steady state, the temperature of the upper and lower surfaces of the sample plate is T 1 and T 2 The heat flux transferred from the heating plate to the sample plate is equal to the heat dissipation from the heat dissipation plate to the surrounding environment. The thermal conductivity of the sample plate can be obtained by the following formula:

[0077]

[0078] Where R is the radius of the heat sink.

[0079] The general formula of the second-order fitting curve can be written as T = a·t 2 +b·t+c, where a, b and c are fitting constants, which can be found in the fitting graph. By taking the derivative of the fitting curve, we can get Substituting the steady-state temperature into the fitting formula to obtain the time, and substituting the time within the measurement range into the derivative formula to obtain the heat dissipation slopes are

[0080] K 1 =-0.1143℃ / s; (T 1 =92.7℃T 2 =56.2°C);

[0081] K 2 =-0.1152℃ / s; (T 1 =92.6℃,T 2 =57.0°C);

[0082] K 3 =-0.1138℃ / s; (T 1 =92.5℃,T 2 =54.8°C);

[0083] K 4 =-0.1233℃ / s(T 1 =93.0℃,T 2 =57.0°C);

[0084] K 5 =-0.1187℃ / s; (T 1 =92.6℃,T 2 =56.0°C);

[0085] K 6 =-0.1095℃ / s; (T 1 =91.7℃,T 2 =56.7°C);

[0086] Combining formulas The thermal conductivity can be obtained as:

[0087] k 1 =0.2683W / (m·℃);(T 1 =92.7℃T 2 =56.2°C);

[0088] k 2 =0.2773W / (m·℃);(T 1 =92.6℃,T 2 =57.0°C);

[0089] k 3 =0.2586W / (m·℃);(T 1 =92.5℃,T 2 =54.8°C);

[0090] k 4 =0.2934W / (m·℃);(T 1 =93.0℃,T 2 =57.0°C);

[0091] k 5 =0.2779W / (m·℃);(T 1 =92.6℃,T2 =56.0°C);

[0092] k 6 =0.2681W / (m·℃);(T 1 =91.7℃,T 2 =56.7°C);

[0093] The average value of the thermal conductivity can be obtained as 0.2739 W / (m·℃), and the experimental accuracy is 0.005. Therefore, the thermal conductivity can be expressed as: (0.274±0.005) W / (m·℃).

[0094] For example, in this embodiment, the thermal conductivity of the sample disk is calculated by using a powerful fan. The difference between the experimental data and the fitting data is large, and the average thermal conductivity of the sample disk is finally calculated to be: (0.31±0.02)W / (m·℃); using semiconductors, the experimental curve and the fitting curve are in good agreement, and the thermal conductivity of the sample is: (0.274±0.005)W / (m·℃). The reference range of rubber thermal conductivity is 0.19~0.24W / (m·℃).

[0095] The accuracy of this experiment is 0.005, and the time corresponding to each stage is shown in Table 1:

[0096] Table 1 The time corresponding to each stage of the experimental process

[0097] Experimental procedures Time / minute The sample pan is heated to steady state 40 Heat sink heating 15 Heat sink heat dissipation 8

[0098] This embodiment uses multiple acrylic plates, butterfly screws, ceramic heating plates and semiconductor heat sinks, combined with an adjustable regulated DC power supply, a digital high-precision four-channel thermometer and a computer to design and build an experimental platform. The conclusions are as follows:

[0099] Based on Fourier's law, an automatic thermal conductivity measurement device was built using an acrylic bracket, a digital high-precision four-channel thermometer, a computer, and a stabilized power supply, which simplified the thermal conductivity experimental measurement operation, reduced the cost of the instrument, and made it automated.

[0100] The experimental process intuitively presents a curve graph of temperature changing with time, realizes the simultaneous measurement of time and temperature, and the automatic measurement of time and temperature, improves the measurement accuracy of thermal conductivity, and reduces the measurement error of temperature stabilization point;

[0101] Compared with semiconductor radiators and powerful fans, semiconductor radiators reduce the impact of powerful cooling fans on the natural cooling curve and effectively reduce the noise during operation;

[0102] When using a powerful fan, the difference between the experimental data and the fitting data is large, and the final calculated average thermal conductivity of the sample disk is: (0.31±0.02)W / (m·℃); when using a semiconductor, the experimental curve and the fitting curve are in good agreement, and the thermal conductivity of the sample is: (0.274±0.005)W / (m·℃). The reference range of rubber thermal conductivity is 0.19~0.24W / (m·℃).

[0103] The technical features of the above embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of the present invention.

Claims

1. An automatic thermal conductivity measuring device, characterized in that: It includes a sample holder, a heating module, a sample tray (7), a heat dissipation module, a voltage-stabilized power supply, a thermometer and a computer; The heating module comprises a heat-insulating ceramic (4), a ceramic heating plate (5) and a heating plate (6) which are sequentially mounted on the sample holder from top to bottom; wherein the voltage-stabilized power supply is electrically connected to the ceramic heating plate (5), and the ceramic heating plate (5) is heated by the voltage-stabilized power supply; The heat dissipation module comprises a heat dissipation plate (8) and a heat sink (9) which are placed in sequence from top to bottom; During heating, the sample plate of the heating module and the heat dissipation module are placed in close contact from top to bottom until the temperature of the heating plate (6) and the heat dissipation plate (8) reaches a steady state, and then the heating plate (6) is directly contacted with the heat dissipation plate (8) so that the temperature of the heat dissipation plate (8) reaches a preset temperature, and then the sample plate (7) is placed back between the heating plate (6) and the heat dissipation plate (8); The thermometer is a digital high-precision four-channel thermometer, which is used to detect the side of the heating plate, between the heating plate and the upper surface of the sample plate, between the lower surface of the sample plate and the heat sink, and the side of the heat sink, and respectively measures the temperature change data of the upper and lower ends of the heating plate (6), the heat sink (8) and the sample plate (7) and the corresponding time; The computer is used to obtain temperature change data and corresponding time from a thermometer, determine a temperature and time change curve, determine the heat dissipation of the heat dissipation disk (8) by using a polynomial fitting method to measure the heat dissipation rate of the heat dissipation disk (8), and obtain the thermal conductivity of the sample disk (7) when the temperatures of the heating disk and the heat dissipation disk reach a steady state and the heat transferred from the heating disk to the sample disk is equal to the heat dissipation of the heat dissipation disk.

2. The automatic thermal conductivity measuring device according to claim 1, characterized in that: The sample holder comprises a first acrylic plate (1), a second acrylic plate (2), a third acrylic plate (3), a butterfly screw (10) and a screw rod (11).

3. The automatic thermal conductivity measuring device according to claim 1, characterized in that: The voltage-stabilized power supply is an adjustable direct current voltage-stabilized power supply.

4. The automatic thermal conductivity measuring device according to claim 1, characterized in that: The sample plate (7), the heating plate (6) and the heat dissipation plate (8) are all in the shape of round sheets with a certain thickness; wherein the diameter range of the sample plate (7), the heating plate (6) and the heat dissipation plate (8) is selected to be 60 to 130 mm, and the thickness range is selected to be 5 to 10 mm.

5. The automatic thermal conductivity measuring device according to claim 1, characterized in that: The heating plate (6) and the heat dissipation plate (8) are made of red copper.

6. The automatic thermal conductivity measuring device according to claim 1, characterized in that: The heat sink includes a semiconductor cooling sheet and a fan.

7. An automatic thermal conductivity measurement method, characterized in that: include: Assemble and fix the automatic thermal conductivity measuring device through the sample holder so that the ceramic heating plate, the heating plate, the sample plate and the heat dissipation plate are in close contact; The ceramic heating plate is heated by a voltage-stabilized power supply, and the ceramic heating plate is in direct contact with the heating plate, so that the heat is transferred from the heating plate to the heat dissipation plate from top to bottom through the sample plate. At the same time, the temperature of the heating plate, the heat dissipation plate and the upper and lower ends of the sample plate is measured by a thermometer until the temperature of the heating plate and the heat dissipation plate reaches a steady state; the thermometer is a digital high-precision four-channel thermometer; When the temperatures of the heating plate and the heat dissipation plate reach a steady state, the heating plate is directly contacted with the heat dissipation plate; when the temperature of the heat dissipation plate is heated to a preset temperature, the sample plate is directly placed on the heat dissipation plate, and the collected temperature of the heat dissipation plate and the corresponding time are transmitted to the computer through a thermometer to obtain a temperature and time variation curve; According to the temperature and time variation curve, the heat passing through the sample disk and the heat dissipation rate of the heat dissipation disk are obtained. The heat dissipation rate of the heat dissipation disk is fitted by a polynomial fitting method to determine the heat dissipation of the heat dissipation disk. When the temperatures of the heating disk and the heat dissipation disk reach a steady state, the heat transferred from the heating disk to the sample disk is equal to the heat dissipation of the heat dissipation disk, and the thermal conductivity of the sample disk is obtained.

8. The automatic thermal conductivity measurement method according to claim 7, characterized in that: The step of obtaining the thermal conductivity of the sample disk according to the fact that the heat transferred from the heating disk to the sample disk is equal to the heat dissipated by the heat dissipation disk when the temperatures of the heating disk and the heat dissipation disk reach a steady state specifically includes: The area of ​​the upper and lower ends is A. According to Fourier's law, the heat passing through the sample plate in time t is obtained using the following formula: Wherein, T1 and T2 are the upper and lower temperatures of the sample plate when reaching steady state, h is the thickness of the heat sink, A is the upper and lower areas of the heat sink and sample plate, and k is the thermal conductivity of the sample plate; When the heat transfer reaches a steady state, the temperatures T1 and T2 of the upper and lower surfaces of the sample plate remain unchanged, and the heat flux transferred from the heating plate to the sample plate is equal to the heat dissipation of the heat dissipation plate to the surrounding environment. The heat dissipation rate of the heat dissipation plate at the steady-state temperature T2 is used to obtain the heat flux of the heat dissipation plate using the following formula: Where m is the mass of the heat sink, c is the specific heat capacity of the heat sink; Then, the thermal conductivity of the sample disk is obtained using the following formula: Where R is the radius of the heat sink.

9. The automatic thermal conductivity measurement method according to claim 7, characterized in that: The step of measuring the temperatures of the heating plate, the heat dissipation plate, and the upper and lower ends of the sample plate by a thermometer specifically includes: Place the K-type thermocouple measuring heads on the side of the heating plate, between the heating plate and the upper surface of the sample plate, between the lower surface of the sample plate and the heat sink, and on the side of the heat sink. Insert the other end into the four corresponding channels of the digital high-precision four-channel thermometer to measure the temperatures of the heating plate, heat sink, and upper and lower ends of the sample plate.

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