CN114113203A - Material thermal conductivity testing method and device convenient to operate - Google Patents

Abstract

The invention relates to a convenient and convenient material thermal conductivity testing method and device. The method comprises the following steps: 1) arranging and connecting a material thermal conductivity testing device; 2) controlling a DC power supply to heat a constant temperature ceramic heating sheet, and using The constant temperature ceramic heating plate is used as a heat source, so that the heat is transferred from the constant temperature ceramic heating plate to the heat dissipation copper plate through the sample; 3) The data logger measures the temperature of the constant temperature ceramic heating plate and the heat dissipation copper plate respectively through the K-type thermocouple, until it reaches stability; 4) Turn off DC power supply, measure the temperature change of the heat-dissipating copper plate during the natural cooling process through K-type thermocouple, use the data logger to transmit the collected temperature data to the computer, and the computer draws the cooling curve of the heat-dissipating copper plate during the natural cooling process, and calculates the heat dissipation through the cooling curve. The heat dissipation rate of the copper plate, and then the heat transfer rate of the sample, that is, the thermal conductivity. Compared with the prior art, the present invention has the advantages of simple operation, convenient and accurate calculation, and low cost.

Description

A method and device for measuring thermal conductivity of materials with convenient operation

technical field

The invention relates to the technical field of thermal conductivity testing of materials, in particular to a method and device for testing thermal conductivity of materials with convenient operation.

Background technique

In the actual engineering field, it is a very critical issue to quickly and accurately determine the thermal properties of materials. According to the thermal properties of materials, the thermal properties of materials can be judged and the materials can be classified. Among them, thermal conductivity, also known as thermal conductivity, is a kind of thermophysical parameter, and also an important parameter to measure the thermal conductivity of materials, which directly reflects the ability of materials to conduct heat and characterizes the efficiency of heat transfer between objects.

For different materials, the thermal conductivity is different. For the same material, the thermal conductivity will also vary with factors such as temperature, pressure, humidity, structure and weight of the substance. Therefore, the appropriate test method is to obtain accurate thermal conductivity. important means of rate. At present, there are two main ways to obtain the thermal conductivity of materials, namely theoretical calculation and experimental measurement. Among them, the theoretical calculation method needs to consider many factors, the calculation process is more complicated, and the application range is narrow, and it is only suitable for specific substances under specific conditions, so there is often a large error between the predicted value and the actual value. , generally not adopted; experimental measurement is the main method to obtain the thermal conductivity of materials, and can be divided into steady-state method and unsteady-state method according to the state of heat flow.

The commonly used steady-state methods are the plate method, the guard plate method, and the heat flow meter method. This method is based on the principle of heat transfer balance, that is, the heat transfer rate and the heat dissipation rate are consistent. As long as the temperature gradient at both ends of the material to be measured and the heat flow value flowing through its unit area are known, its thermal conductivity can be calculated by the Fourier formula. . Among them, the advantage of the steady-state guard plate method is that the measurement temperature range is large, but due to the large error caused by the temperature imbalance, this problem has always been a technical problem, although the use of a thermopile composed of multiple thermocouples can be reduced. error, but the number of thermocouples is not infinite to improve the sensitivity of the sensor, although the use of ultra-high precision digital voltmeter for measurement and control can reduce the number of thermocouples in the thermop The method of thermal conductivity meter is not realistic; the measurement time of the steady-state heat flow meter method is too long, and the heat loss is large, and when measuring materials with large thermal resistance and ultra-low thermal conductivity, the heat flow meter in the thermal flow meter method is in the ultra-low thermal conductivity. The low heat flow in the coefficient test has a large error in the measurement, and it is impossible to calibrate the heat flow meter and calibrate the standard material with ultra-low thermal conductivity. Therefore, the steady-state shield method and the steady-state heat flow meter method often have great limitations in the application of measuring the thermal conductivity of materials.

Commonly used non-steady state method, also known as transient method, commonly used transient hot wire method, transient plane heat source method, laser flash method. The principle is to draw the temperature response curve of the sample based on the change of the temperature field in the measurement system and the sample with time, so as to obtain the thermal conductivity of the sample. Among them, although the transient hot wire method has certain advantages in measurement accuracy and measurement time, the measurement device of this method is complicated, the cost is high, and it is more used in the measurement of the thermal conductivity of fluid materials, not suitable for the thermal conductivity of solid materials. In addition, the test repeatability of this method is poor; the transient plane heat source method faces the same problems as the transient hot wire method, and the stability and repeatability of the test results require a large amount of reliable data support, and This method is only suitable for measuring materials with low thermal conductivity, and is often used to test the thermal conductivity of solid materials in the actual test selection process; the laser flash method can be used to directly measure the thermal diffusion properties of materials, with a wide measurement range, and Non-destructive temperature sensing can achieve high-precision measurement, but this method requires very high sample pretreatment, and the sample processing has a great impact on the experimental results.

To sum up, among many test methods, the steady-state flat plate method is a classic method for measuring the thermal conductivity of medium and low temperature materials. The absolute value and the advantages of being suitable for a wide temperature range have been widely used. However, it is worth noting that the device for measuring thermal conductivity by the steady-state method is still relatively complicated, which greatly increases the cost of the test. Therefore, a new thermal conductivity test method with simple device and low cost is urgently needed.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a convenient and convenient material thermal conductivity testing method and device in order to overcome the above-mentioned defects of the prior art.

The object of the present invention can be realized through the following technical solutions:

A convenient and convenient testing method for thermal conductivity of materials, the method comprises the following steps:

1) Lay out and connect the material thermal conductivity test device, so that the constant temperature ceramic heating sheet, the sample and the heat dissipation copper plate are closely attached;

2) Control the DC power supply to heat the constant temperature ceramic heating sheet, and use the constant temperature ceramic heating sheet as the heat source, so that the heat is transferred from the constant temperature ceramic heating sheet to the heat dissipation copper plate through the sample;

3) The data recorder measures the temperature of the constant temperature ceramic heating plate and the heat dissipation copper plate respectively through the K-type thermocouple until it reaches stability;

4) Turn off the DC power supply, measure the temperature change of the heat-dissipating copper plate during the natural cooling process through the K-type thermocouple, use the data logger to transmit the collected temperature data to the computer, and the computer draws the cooling curve of the heat-dissipating copper plate during the natural cooling process. The curve calculates the heat dissipation rate of the heat dissipation copper plate, and then obtains the heat transfer rate of the sample, that is, the thermal conductivity.

In the step 3), when the temperature is stable, the temperature of the heat-dissipating copper plate is taken as the upper surface temperature T ₁ of the sample, and the temperature of the thermostatic ceramic heating sheet is taken as the lower surface temperature T ₂ of the sample.

In the step 4), under the condition that the size of the sample is small enough, the heat radiated from the side of the sample to the surrounding environment is ignored, and the heat transfer rate of the sample is considered to be equal to the heat dissipation rate of the heat dissipation copper plate, the thermal conductivity of the sample is λ. The calculation formula is:

Among them, L is the thickness of the sample, S _s is the upper surface area, and S _s =D ² π/4, D is the diameter of the heat-dissipating copper plate, m and c are the mass and specific heat capacity of the heat-dissipating copper plate 4, respectively, and c is a fixed value 0.3709J/(g·K), K is the natural cooling rate of the heat-dissipating copper plate at T ₁ , and δ is the thickness of the heat-dissipating copper plate.

_The natural cooling rate K of the cooling copper plate at T1 is obtained by the following method:

When the temperature of the heat-dissipating copper plate and the constant temperature ceramic heating sheet is stable, turn off the DC power supply, measure and record the relationship between the temperature T of the heat-dissipating copper plate and the time t during natural cooling, and obtain the cooling curve. The tangent slope of the cooling curve is the natural cooling rate. When When the temperature of the heat dissipation copper plate is T ₁ , the natural cooling rate K can be obtained, then:

This test method is suitable for testing the thermal conductivity of solid materials in the low temperature field.

The solid material is a phase change composite material, specifically a hybrid graphene aerogel phase change composite material.

A convenient and easy-to-operate material thermal conductivity testing device, the device includes a DC power supply, a constant-temperature ceramic heating plate, a sample, a heat-dissipating copper plate, a K-type thermocouple, a data recorder and a computer, and the upper and lower surfaces of the sample are respectively connected to the The heat-dissipating copper plate and the constant-temperature ceramic heating plate are closely attached. The data recorder measures the temperature change data of the heat-dissipating copper plate and the constant-temperature ceramic heating plate respectively through a K-type thermocouple and sends it to the computer. The DC power supply is used for the constant-temperature ceramic heating plate. The heating plate is powered to achieve heating.

The DC power supply is a 5V DC power supply, the constant temperature ceramic heating plate is a PTC heating plate, and the data recorder is a four-channel thermometer recorder. The maximum DC voltage and AC voltage it can withstand are 60V and 24V, respectively.

The sample is a disk-shaped sample with a diameter of 25 mm and a thickness of 5 mm, and the temperature distribution on the upper and lower surfaces is uniform, ignoring the heat emitted from the side of the sample to the surrounding environment.

The heat-dissipating copper plate is a disk-shaped sample with a specific heat capacity of 0.385×10 ³ J/(kg·°C) and a thickness of 8.00 mm.

Compared with the prior art, the present invention has the following advantages:

The test device of the invention is only composed of a DC power supply, a constant temperature ceramic heating piece, a sample, a heat dissipation copper plate, a K-type thermocouple, a data recorder and a computer. The device is simple and the test process is concise and clear, which can not only greatly improve the thermal conductivity test At the same time, it can overcome the disadvantages of the high cost of the original thermal conductivity tester. In addition, the sample size is small, on the one hand, it can avoid the heat loss caused by the excessive sample size, and on the other hand, it can also avoid the excessive sample size. The resulting large investment in experimental funds further meets the economic requirements.

Description of drawings

FIG. 1 is a schematic diagram of the device structure of the present invention.

FIG. 2 is a schematic diagram of the heat transfer process in the experiment of the present invention.

3 is a graph of the thermal conductivity of the elastic phase change composite material prepared by the vacuum impregnation method under different concentrations and different pH values tested by the present invention.

Figure 4 is a graph of the thermal conductivity of the elastic phase change composites prepared by the vacuum impregnation method under different concentrations and different pH values tested by the MDSC method.

FIG. 5 is a graph of the thermal conductivity of the composite phase change material prepared by the ion crosslinking method under different crosslinking materials tested by the method of the present invention.

Description of marks in the figure:

1. DC power supply, 2. Constant temperature ceramic heating plate, 3. Sample, 4. Cooling copper plate, 5. K-type thermocouple, 6. Data recorder, 7. Computer.

Detailed ways

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

On the basis of the existing thermal conductivity testing method, the invention proposes a convenient and convenient testing method for the thermal conductivity of materials, namely the steady-state plate method. The principle of the method is based on the Fourier one-dimensional steady-state heat conduction model. , the heat is conducted from the constant temperature ceramic heating plate 2 to the heat dissipation copper plate 4 through the sample 3. When the temperature reaches a stable state, the temperature of the upper and lower surfaces of the sample 3 can be obtained. Since the sample is thin, the heat emitted from the side of the sample to the surrounding environment is ignored. , that is, the heat transfer rate of the sample is considered to be equal to the rate at which the heat dissipation copper plate 4 dissipates heat to the surrounding environment, and its cooling rate is calculated through the cooling curve of the heat dissipation copper plate 4, and then the heat dissipation rate and the heat transfer rate of the sample 3 are obtained. Leaf's law, the thermal conductivity of the sample can be calculated.

As shown in FIG. 1 , the present invention provides a method and device for testing the thermal conductivity of materials with convenient operation. The main components of the testing device include a DC power supply 1, a constant temperature ceramic heating sheet 2, a sample 3, a heat dissipation copper plate 4, a K-type thermoelectric Couple 5, data recorder 6 and computer 7.

Among them, the DC power supply 1 adopts a DC power supply with a voltage of 5V, and the main function in this device is to heat the constant temperature ceramic heating plate 2 to keep the temperature of the constant temperature ceramic heating plate 2 stable; the constant temperature ceramic heating plate 2 is a PTC heating plate , the heating temperature is about 40 ℃, the main function in this device is to provide a stable heat source for the sample, so that the sample can be heated evenly; sample 3 is a disc-shaped sample with a diameter of 25mm and a thickness of 5mm; the heat dissipation copper plate 4 adopts a specific heat capacity of 0.385 ×10 ³ J/(kg·℃), the thickness of 8.00mm disc copper plate has two functions in the device, one is to cover the upper surface of the sample to prevent the upper surface of the sample from emitting too much heat to the surrounding environment Among them, the second is that the heat transfer rate of the sample 3 can be obtained indirectly through the heat dissipation rate of the heat dissipation copper plate 4; the K-type thermocouple 5 is used to measure the temperature of the heat dissipation copper plate 4 and the constant temperature ceramic heating plate 2; the data recorder 6 is a four-channel thermometer recording The measurable temperature range is -200~1370℃, and the maximum DC voltage and AC voltage that can withstand are 60V and 24V respectively. temperature; the function of the computer 7 is to collect the data in the data recorder and draw the cooling curve during the cooling process of the heat-dissipating copper plate.

The method of using this device for material thermal conductivity testing includes the following three steps:

1) Before connecting the power supply, arrange the DC power supply 1, the constant temperature ceramic heating piece 2, the sample 3, the heat dissipation copper plate 4, the K-type thermocouple 5, the data recorder 6, and the computer 7 as shown in FIG. 1, wherein the constant temperature ceramic heating Sheet 2, the sample and the heat dissipation copper plate 4 need to be closely attached to reduce heat loss;

2) Connect the constant temperature ceramic heating piece 2 to the DC power supply 1, and heat the constant temperature ceramic heating piece 2 by controlling the DC power supply 1, and use it as a heat source, and the heat is transferred from the constant temperature ceramic heating piece 2 to the heat dissipation copper plate 4 (heat) through the sample 3. The transfer process is shown in Figure 2), the data recorder 6 is connected to the constant temperature ceramic heating plate 2 and the heat dissipation copper plate 4 through the K-type thermocouple 5 respectively, and a reading is performed every 5min. When the change occurs, it is considered that the temperature of the heat dissipation copper plate 4 and the constant temperature ceramic heating plate 2 reaches a stable value, which are T ₁ and T ₂ respectively, because the upper and lower surfaces of the sample 3 are in close contact with the heat dissipation copper plate 4 and the constant temperature ceramic heating plate 2 respectively. , so T ₁ and T ₂ can be used to represent the upper and lower surface temperatures of sample 3, respectively;

3) Turn off the DC power supply 1, measure the temperature change during the cooling process of the heat-dissipating copper plate 4 through the K-type thermocouple 5, use the data recorder 6 to transmit the collected data to the computer 7, draw the cooling curve of the heat-dissipating copper plate 4 during the cooling process, and pass From the cooling curve, the heat dissipation rate of the heat dissipation copper plate 4 was calculated, and the heat transfer rate of the sample 3 was further obtained.

The calculation process of the thermal conductivity of the sample under this device is as follows:

(1) Calculate the heat transfer rate of the sample according to the temperature of the upper and lower surfaces of the measured sample 3:

S _s =D ² π/4

为样品的传热速率；L、S_s、T₁和T₂分别为样品的厚度、上表面面积、上表面的温度和下表面的温度，D为散热铜板的直径，λ为导热系数；in,

is the heat transfer rate of the sample; L, S _s , T ₁ and T ₂ are the thickness of the sample, the area of the upper surface, the temperature of the upper surface and the temperature of the lower surface, D is the diameter of the heat dissipation copper plate, λ is the thermal conductivity;

表示样品在竖直方向上的平均温度梯度，因为样品3性质均匀，所以认为所有水平截面上的温度梯度都等于这一平均值，此外，样品3较薄，样品侧面散发到周围环境中的热量可以忽略不计，即认为样品3的传热速率与散热铜板4的散热速率相等，但散热铜板4的散热速率无法直接测得，实验过程中通过测试散热铜板4的冷却速率来计算其散热速率。

Represents the average temperature gradient of the sample in the vertical direction. Because the sample 3 is uniform in nature, the temperature gradient on all horizontal sections is considered to be equal to this average value. In addition, the sample 3 is thinner, and the heat emitted from the side of the sample to the surrounding environment It can be ignored, that is, it is considered that the heat transfer rate of sample 3 is equal to the heat dissipation rate of heat dissipation copper plate 4, but the heat dissipation rate of heat dissipation copper plate 4 cannot be directly measured. During the experiment, the cooling rate of heat dissipation copper plate 4 was tested to calculate its heat dissipation rate.

(2) When the temperature of the heat-dissipating copper plate 4 and the constant-temperature ceramic heating piece 2 is stable, turn off the DC power supply, record the relationship between the temperature and the time when the heat-dissipating copper plate 4 is naturally cooled, and obtain the relationship curve between the two, which is the cooling curve, and find out its The natural cooling rate, denoted as K, is the slope of the tangent to the cooling curve. Therefore, the cooling rate of the cooling copper plate 4 during natural cooling has the following relationship with temperature and time:

When the temperature of the heat dissipation copper plate ₄ is T1, the relationship between its natural cooling rate, temperature and time is:

And because the heat dissipation rate of the heat dissipation copper plate 4 has the following relationship with the cooling rate during natural cooling:

为散热铜板4自然冷却时的散热速率，m和c分别为散热铜板4的质量和比热容，c为固定值0.3709J/(g·K)。因此，当散热铜板4温度为T₁时，散热铜板4的散热速率与其自然冷却时的冷却速率的关系为：in

is the heat dissipation rate when the heat dissipation copper plate 4 is naturally cooled, m and c are the mass and specific heat capacity of the heat dissipation copper plate 4 respectively, and c is a fixed value of 0.3709J/(g·K). Therefore, when the temperature of the heat dissipation copper plate ₄ is T1, the relationship between the heat dissipation rate of the heat dissipation copper plate 4 and its cooling rate during natural cooling is:

(3) The ratio of the heat transfer rate of the sample 3 to the heat dissipation rate of the heat dissipation copper plate 4:

where δ is the thickness of the heat-dissipating copper plate; according to Fourier's law, calculate the thermal conductivity of the sample:

Among them, K is the natural cooling rate _of the heat dissipation copper plate at T1.

The following content is an introduction to an example of the present invention

The main structure of the easy-to-operate material thermal conductivity testing device of the present invention includes the following parts:

DC power supply 1, constant temperature ceramic heating plate 2, sample 3, heat dissipation copper plate 4, K-type thermocouple 5, data recorder 6, computer 7.

During the experiment, the DC power supply 1 is connected to the constant temperature ceramic heating plate 2, the constant temperature ceramic heating plate 2 is heated by controlling the DC power supply 1, the sample is placed between the constant temperature ceramic heating plate 2 and the heat dissipation copper plate 4, and the data recorder 6 is connected. The two thermocouples 5 are respectively connected with the constant temperature ceramic heating plate 2 and the heat dissipation copper plate 4, and are used to measure the temperature of the constant temperature ceramic heating plate 2 and the heat dissipation copper plate 4, and connect the data recorder 6 with the computer 7 to realize data collection and calculation. .

During the temperature test, keep a constant heat source and take readings every 5 minutes. When the data displayed in the data recorder 6 does not change for 10 minutes, it is considered that the temperature of the heat dissipation copper plate 4 and the constant temperature ceramic heating plate 2 has reached a stable value. , respectively T ₁ and T ₂ , because the upper and lower surfaces of the sample 3 are in close contact with the heat-dissipating copper plate 4 and the constant temperature ceramic heating plate 2 respectively, so T ₁ and T ₂ can be used to represent the temperature of the upper and lower surfaces of the sample 3, respectively. In addition, the sample The thickness of 3 is very small, ignoring the heat dissipated from the side of sample 3 to the surrounding environment, it is considered that the heat transfer rate of sample 3 is equal to the heat dissipation rate of heat dissipation copper plate 4, but the heat dissipation rate of heat dissipation copper plate 4 cannot be directly measured. The cooling rate of the heat dissipation copper plate 4 can be calculated by the cooling rate, and the cooling rate of the heat dissipation copper plate 4 can be obtained by the cooling curve of the heat dissipation copper plate 4.

Therefore, when the temperature is stable, turn off the DC power supply 1, connect the data recorder 6 to the computer 7 at the same time, collect the data of the temperature change with time when the cooling copper plate 4 is naturally cooled, and process the relationship curve between the two, which is the cooling copper plate 4 and calculate the natural cooling rate of the cooling copper plate 4, denoted as K, which is the slope of the tangent to the cooling curve. Finally, according to the Fourier one-dimensional steady-state heat conduction model, calculate the thermal conductivity of the sample:

Where L is the thickness of the sample, m, D, δ, c and K are the mass, diameter, thickness, specific heat capacity and cooling rate of the heat dissipation copper plate 4 respectively, and c is a fixed value of 0.3709J/(g·K).

Example 1

The present invention is used to test the thermal conductivity of the pure paraffin provided by Sinopharm Chemical Reagent Co., Ltd. The test results are shown in column 1 in Figure 3. The thermal conductivity of the paraffin tested by the method of the present invention is 0.254W·m ^-1 ·K ^{- 1} ; At the same time, the thermal conductivity of the paraffin was tested by the MDSC thermal conductivity test method. The test results are shown in curve c in Figure 4. The thermal conductivity of the paraffin tested by the MDSC method was 0.224W·m ^-1 ·K ^-1 . Under the two different test methods, the test results of thermal conductivity are in good agreement.

Example 2

The method of the present invention is used to test the thermal conductivity of the elastic phase change composite material prepared by the vacuum impregnation method. The composite material comprises elastic emulsion (EE), phase change material and thermally conductive filling material, wherein the phase change material is paraffin, and the thermally conductive filling material is 3D graphene aerogel. The paraffin wax is provided by Sinopharm Chemical Reagent Co., Ltd., the specification is chemically pure, the melting point is 48-52°C, and the density is 0.86g/cm ³ ; 200 mesh natural flake graphite is provided by Shanghai Yifan Graphite Products Co., Ltd. The test results are shown in column 2 of Figure 3. The thermal conductivity of the elastic phase change composite prepared under the conditions that the pH of graphene oxide is 2, the concentration is 12 mg/ml, and the MPCM:EE is 1:1 is 0.354 W· m ^-1 ·K ^-1 , and the thermal conductivity of the elastic phase change composite material was tested by the MDSC thermal conductivity test method. The test results are shown in curve b in Figure 4. The thermal conductivity tested by the MDSC method was 0.313W. ·m ⁻¹ ·K ⁻¹ . Under the two different test methods, the test results of thermal conductivity are in good agreement.

Example 3

The method of the present invention is used to test the thermal conductivity of the elastic phase change composite material prepared by the vacuum impregnation method. The composite material comprises elastic emulsion (EE), phase change material and thermally conductive filling material, wherein the phase change material is paraffin, and the thermally conductive filling material is 3D graphene aerogel. The paraffin wax is provided by Sinopharm Chemical Reagent Co., Ltd., the specification is chemically pure, the melting point is 48-52°C, and the density is 0.86g/cm ³ ; 200 mesh natural flake graphite is provided by Shanghai Yifan Graphite Products Co., Ltd. The test results are shown in Figure 3, column 3. The thermal conductivity of the elastic phase change composite material prepared under the conditions that the pH of graphene oxide is 11, the concentration is 12 mg/ml, and the MPCM:EE is 1:1 is 0.480W· m ^-1 ·K ^-1 , and the thermal conductivity of the elastic phase change composite material was tested by the MDSC thermal conductivity test method. The test results are shown in curve a in Figure 4. The thermal conductivity tested by the MDSC method was 0.465W. ·m ⁻¹ ·K ⁻¹ . Under the two different test methods, the test results of thermal conductivity are in good agreement.

Example 4

The method of the present invention is used to test the thermal conductivity of the hybrid graphene aerogel phase change composite material prepared by the ion crosslinking method. The composite material comprises a crosslinking material, a phase change material and a thermally conductive filling material, wherein the crosslinking material is KCl , the phase change material is paraffin, and the thermally conductive filling material is hybrid graphene aerogel. The paraffin wax is provided by Sinopharm Chemical Reagent Co., Ltd., the specification is chemically pure, the melting point is 48-52°C, and the density is 0.86g/cm ³ ; 200 mesh natural flake graphite is provided by Shanghai Yifan Graphite Products Co., Ltd. The test results are shown in Figure 5, column 1. When the cross-linked material is a 160 mM KCl solution, the thermal conductivity of the prepared hybrid graphene aerogel phase change composite is 0.440 W·m ^-1 ·K ^-1 .

Example 5

The method of the present invention is used to test the thermal conductivity of the hybrid graphene aerogel phase change composite material prepared by the ion crosslinking method. The composite material comprises a crosslinking material, a phase change material and a thermally conductive filling material, wherein the crosslinking material is KCl , the phase change material is paraffin, and the thermally conductive filling material is hybrid graphene aerogel. The paraffin wax is provided by Sinopharm Chemical Reagent Co., Ltd., the specification is chemically pure, the melting point is 48-52°C, and the density is 0.86g/cm ³ ; 200 mesh natural flake graphite is provided by Shanghai Yifan Graphite Products Co., Ltd. The test results are shown in column 2 of Figure 5. When the cross-linked material is 200 mM KCl solution, the thermal conductivity of the prepared hybrid graphene aerogel phase change composite is 0.467 W·m ^-1 ·K ^-1 .

Example 6

The method of the present invention is used to test the thermal conductivity of the hybrid graphene aerogel phase change composite material prepared by the ion crosslinking method. The composite material comprises a crosslinking material, a phase change material and a thermally conductive filling material, wherein the crosslinking material is MgCl _2. The phase change material is paraffin, and the thermally conductive filling material is hybrid graphene aerogel. The paraffin wax is provided by Sinopharm Chemical Reagent Co., Ltd., the specification is chemically pure, the melting point is 48-52°C, and the density is 0.86g/cm ³ ; 200 mesh natural flake graphite is provided by Shanghai Yifan Graphite Products Co., Ltd. The test results are shown in Figure 5, column 3, when the cross-linked material is 200 mM MgCl ₂ solution, the thermal conductivity of the prepared hybrid graphene aerogel phase change composite is 0.560 W·m ^-1 ·K ^-1 .

Example 7

The method of the present invention is used to test the thermal conductivity of the hybrid graphene aerogel phase change composite material prepared by the ion crosslinking method. The composite material comprises a crosslinking material, a phase change material and a thermally conductive filling material, wherein the crosslinking material is MgCl _2. The phase change material is paraffin, and the thermally conductive filling material is hybrid graphene aerogel. The paraffin wax is provided by Sinopharm Chemical Reagent Co., Ltd., the specification is chemically pure, the melting point is 48-52°C, and the density is 0.86g/cm ³ ; 200 mesh natural flake graphite is provided by Shanghai Yifan Graphite Products Co., Ltd. The test results are shown in Figure 5, column 4, when the cross-linked material is 240 mM MgCl ₂ solution, the thermal conductivity of the prepared hybrid graphene aerogel phase change composite is 0.548 W·m ^-1 ·K ^-1 .

Example 8

The method of the present invention is used to test the thermal conductivity of the hybrid graphene aerogel phase change composite material prepared by the ion crosslinking method. The composite material comprises a crosslinking material, a phase change material and a thermally conductive filling material, wherein the crosslinking material is FeCl _3. The phase change material is paraffin, and the thermally conductive filling material is hybrid graphene aerogel. The paraffin wax is provided by Sinopharm Chemical Reagent Co., Ltd., the specification is chemically pure, the melting point is 48-52°C, and the density is 0.86g/cm ³ ; 200 mesh natural flake graphite is provided by Shanghai Yifan Graphite Products Co., Ltd. The test results are shown in Figure 5, column 5, when the cross-linked material is 80 mM FeCl ₃ solution, the thermal conductivity of the prepared hybrid graphene aerogel phase change composite is 0.500 W·m ^-1 ·K ^-1 .

Example 9

The method of the present invention is used to test the thermal conductivity of the hybrid graphene aerogel phase change composite material prepared by the ion crosslinking method. The composite material comprises a crosslinking material, a phase change material and a thermally conductive filling material, wherein the crosslinking material is FeCl _3. The phase change material is paraffin, and the thermally conductive filling material is hybrid graphene aerogel. The paraffin wax is provided by Sinopharm Chemical Reagent Co., Ltd., the specification is chemically pure, the melting point is 48-52°C, and the density is 0.86g/cm ³ ; 200 mesh natural flake graphite is provided by Shanghai Yifan Graphite Products Co., Ltd. The test results are shown in Figure 5, column 6, when the cross-linked material is 160 mM FeCl ₃ solution, the thermal conductivity of the prepared hybrid graphene aerogel phase change composite is 0.450 W·m ^-1 ·K ^-1 .

The above embodiments are only for illustrating the specific experimental process and calculation process of the present invention, and are not limited to the materials mentioned in this patent that are easy to operate. For those skilled in the art, this patent can have various modifications and changes, Such as the testing of other materials, that is, this patent does not exclude the testing of other materials, and all modifications, equivalent replacements, and improvements made within the spirit and scope of this patent should be within the scope of protection of this patent. within.

Claims (10)

1. A method for testing the thermal conductivity of a material, which is convenient to operate, is characterized by comprising the following steps:

1) arranging and connecting a material thermal conductivity testing device to enable the constant-temperature ceramic heating sheet (2), the sample (3) and the heat dissipation copper plate (4) to be tightly attached;

2) controlling a direct-current power supply (1) to heat a constant-temperature ceramic heating sheet (2), and using the constant-temperature ceramic heating sheet (2) as a heat source to enable heat to be transferred from the constant-temperature ceramic heating sheet (2) to a heat dissipation copper plate (4) through a sample (3);

3) the data recorder (6) respectively measures the temperature of the constant-temperature ceramic heating plate (2) and the temperature of the heat dissipation copper plate (4) through a K-type thermocouple (5) until the temperatures are stable;

4) the method comprises the steps of closing a direct current power supply (1), measuring the temperature change of a heat dissipation copper plate (4) in the natural cooling process through a K-type thermocouple (5), transmitting collected temperature data to a computer (7) through a data recorder (6), drawing a cooling curve of the heat dissipation copper plate (4) in the natural cooling process through the computer (7), calculating the heat dissipation rate of the heat dissipation copper plate (4) through the cooling curve, and further obtaining the heat transfer rate, namely the heat conductivity, of a sample (3).

2. The method for testing the thermal conductivity of the material with convenient operation according to claim 1, wherein in the step 3), when the temperature is stabilized, the temperature of the heat-dissipating copper plate (4) is taken as the upper surface temperature T of the sample (3)₁The temperature of the constant temperature ceramic heating sheet (2) is taken as the lower surface temperature T of the sample (3)₂。

3. The method for testing the thermal conductivity of the material with convenient operation according to the claim 2 is characterized in that, in the step 4), under the condition that the size of the sample (3) is small enough, the heat emitted from the side surface of the sample to the surrounding environment is ignored, and the heat transfer rate of the sample (3) is considered to be equal to the heat dissipation rate of the heat dissipation copper plate (4), the calculation formula of the thermal conductivity lambda of the sample (3) is as follows:

wherein L is the thickness of the sample, S_sIs an upper surface area, and S_s＝D²Pi/4, D is the diameter of the heat-radiating copper plate, m and c are respectively the mass and the specific heat capacity of the heat-radiating copper plate 4, c is a fixed value 0.3709J/(g.K), and K is the T of the heat-radiating copper plate₁The natural cooling rate, δ, is the thickness of the heat-dissipating copper plate.

4. The method for testing the thermal conductivity of the material, which is convenient to operate, according to claim 3, is characterized in that the heat-radiating copper plate is arranged at T₁The natural cooling rate K of (a) is obtained by:

when the temperatures of the heat dissipation copper plate (4) and the constant temperature ceramic heating plate (2) are stable, the direct current power supply (1) is closed, and the heat dissipation copper plate (4) is measured and recorded when being naturally cooledThe relation between the temperature T and the time T is obtained to obtain a cooling curve, the tangent slope of the cooling curve is the natural cooling rate, and when the temperature of the heat-radiating copper plate (4) is T₁Then, the natural cooling rate K can be obtained, which is:

5. the method for testing the thermal conductivity of the material, which is convenient to operate, is characterized in that the method is suitable for testing the thermal conductivity of the solid material in the low-temperature field.

6. The method for testing the thermal conductivity of a material, which is convenient and fast to operate, according to claim 5, is characterized in that the solid material is a phase-change composite material, specifically a hybrid graphene aerogel phase-change composite material.

7. A testing device for realizing the method for testing the thermal conductivity of the material according to any one of claims 1 to 6, which comprises a direct current power supply (1), a constant temperature ceramic heating plate (2), a sample (3), a heat dissipation copper plate (4), a K-type thermocouple (5), a data recorder (6) and a computer (7), wherein the upper surface and the lower surface of the sample (3) are respectively tightly attached to the heat dissipation copper plate (4) and the constant temperature ceramic heating plate (2), the data recorder (6) respectively measures the temperature change data of the heat dissipation copper plate (4) and the constant temperature ceramic heating plate (2) through the K-type thermocouple (5) and sends the data to the computer (7), and the direct current power supply (1) is used for supplying power to the constant temperature ceramic heating plate (2) to realize heating.

8. The testing device according to claim 7, wherein the DC power supply (1) is a 5V DC power supply, the thermostatic ceramic heater plate (2) is a PTC heater plate, the data recorder (6) is a four-channel thermometer recorder capable of measuring temperatures ranging from-200 to 1370 ℃ and capable of bearing maximum DC voltage and AC voltage of 60V and 24V, respectively.

9. The testing device according to claim 7, characterized in that the sample (3) is a disk-shaped sample with a diameter of 25mm and a thickness of 5mm, and the temperature distribution of the upper and lower surfaces is uniform, neglecting the heat emitted from the sides of the sample to the surrounding environment.

10. The test device according to claim 7, wherein the heat-dissipating copper plate (4) has a specific heat capacity of 0.385 x 10³J/(kg. DEG C.), a disk-like sample having a thickness of 8.00 mm.

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