A fitting method for thermal conductivity coefficient of cable material under high temperature of fire

Abstract

This invention discloses a method for fitting the thermal conductivity coefficient of cable materials under high-temperature fire conditions. The method includes: preparing two sets of cable materials; determining the heat capacity values ​​of the outer sheath and insulation layer of the first set of cable materials at different temperatures; uniformly arranging multiple thermocouples in the outer sheath and insulation layer of the second set of cable materials, and fabricating a stacked test sample using a high-temperature pressing process; conducting an over-temperature test, recording the temperature data of each thermocouple on the over-temperature test sample during the over-temperature test; determining the thermal conductivity coefficient of the cable material at different temperatures; determining the thermal conductivity abrupt change point based on the thermal conductivity coefficient of the cable material at different temperatures, and performing nonlinear fitting on the thermal conductivity coefficient of the cable material before, after, and during the abrupt change to obtain a curve of the cable material's thermal conductivity changing with temperature. This invention solves the technical problem that a fixed thermal conductivity coefficient cannot accurately simulate the real situation of cable fires.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of cable joint fire risk assessment, and in particular, to a fitting method of thermal conductivity coefficient of cable material under high temperature fire. BACKGROUND

[0002] With the growth of energy demand in modern society, the stable operation of the power system is crucial. As a key component of power transmission, the thermal performance of the cable is crucial to the safety and stability of the system. Among the performance indicators of the cable, the thermal conductivity coefficient is a key parameter that affects the heat distribution and heat dissipation effect of the cable during normal operation. Under high temperature fire environment, the sheath and insulation layer structure materials of the cable will be affected by heat and undergo pyrolysis reaction, causing changes in the internal molecular structure of the cable and phase transition of the cable structure, from normal state to molten state, and further pyrolysis from molten state, producing carbonates and combustible gases, etc., resulting in changes in the thermal conductivity coefficient of the cable material, posing a challenge to the safety of the cable system.

[0003] In related technologies, the simulation model of fire usually uses a fixed thermal conductivity coefficient value when calculating the heat transfer of the cable. Although this simplifies the calculation process, it cannot accurately reflect the real thermal behavior of the cable under high temperature environment. The simulation results obtained by using a fixed and single thermal conductivity coefficient cannot accurately predict the temperature distribution, heat transfer and thermal failure mechanism of the cable under high temperature fire environment, thereby affecting the accuracy and reliability of the simulation results.

[0004] At present, there is no effective solution to the above problems. SUMMARY

[0005] The present application provides a fitting method of thermal conductivity coefficient of cable material under high temperature fire, to at least solve the technical problem that a fixed thermal conductivity coefficient cannot accurately simulate the real situation of cable fire.

[0006] According to an aspect of an embodiment of the present application, a fitting method of thermal conductivity coefficient of cable material under high temperature fire is provided, comprising:

[0007] Step 1: Prepare two portions of cable material, press the outer sheath and insulation layer of the first portion of cable material into a sheet with uniform thickness, and perform differential scanning calorimetry test on the outer sheath and insulation layer of the first portion of cable material respectively to determine the respective heat capacity values of the outer sheath and insulation layer of the first portion of cable material at different temperatures;

[0008] Step 2: Press the outer sheath and insulation layer of the second portion of cable material into a sheet with uniform thickness, and arrange multiple thermocouples uniformly on the outer sheath and insulation layer of the second portion of cable material, and make a thermal test sample with a stacked structure through a high temperature pressing process;

[0009] Step 3: build an over-temperature test platform, wherein the over-temperature test platform comprises a simulated fire source device, a cable support, and a high-temperature resistant box;

[0010] Step 4: perform an over-temperature test on the over-temperature test sample, and record the temperature data of each of the plurality of thermocouples when the over-temperature test sample is over-temperature;

[0011] Step 5: determine the thermal conductivity of the cable material at different temperatures according to the thermal capacity values of the outer sheath and the insulation layer of the first cable material at different temperatures obtained in step 1, and the temperature data of each of the plurality of thermocouples when the over-temperature test sample is over-temperature obtained in step 4;

[0012] Step 6: determine the thermal conductivity mutation point of the cable material according to the thermal conductivity of the cable material at different temperatures, and perform nonlinear fitting on the thermal conductivity of the cable material before and after the mutation and during the mutation process, respectively, to obtain a curve graph of the thermal conductivity of the cable material changing with temperature.

[0013] Optionally, in step 1, two cable materials are prepared, the outer sheath and the insulation layer of the first cable material are pressed into a sheet shape with uniform thickness, and differential scanning calorimetry tests are performed on the outer sheath and the insulation layer of the first cable material respectively to determine the thermal capacity values of the outer sheath and the insulation layer of the first cable material at different temperatures, including the following steps:

[0014] Step 1.1: divide the real cable material into two, and press the outer sheath and the insulation layer of the first cable material into a sheet shape with uniform thickness;

[0015] Step 1.2: perform differential scanning calorimetry tests on the outer sheath and the insulation layer of the first cable material respectively to obtain a heat flow-temperature curve, wherein the differential scanning calorimetry test is performed in a nitrogen atmosphere, the gas flow rate is set to V1, the temperature is from T1 to T2, and the heating rate is β; Step 1.3: according to the thermal capacity value formula: obtain the thermal capacity values of the outer sheath and the insulation layer at different temperatures, wherein C p represents the thermal capacity value, ΔH represents the heat flow per unit time on the heat flow-temperature curve, and m represents the mass of the outer sheath or the insulation layer.

[0016] Optionally, in step 2, the outer sheath and the insulation layer of the second cable material are pressed into a sheet shape with uniform thickness, and a plurality of thermocouples are arranged uniformly on the outer sheath and the insulation layer of the second cable material, and a high-temperature pressing process is used to make the over-temperature test sample into a stacked structure, including the following steps:

[0017] Step 2.1: The outer sheath and insulation layer of the second cable material are laminated into a sheet with uniform thickness, and a plurality of same type thermocouples are arranged in an array on the outer sheath and insulation layer of the second cable material respectively;

[0018] Step 2.2: The outer sheath and insulation layer of the second cable material on which a plurality of same type thermocouples are arranged are integrated by a high-temperature pressing process to obtain an over-temperature test sample.

[0019] Optionally, in step 3, an over-temperature test platform is built, wherein the over-temperature test platform includes a simulated fire source device, a cable support, a high-temperature resistant box, and includes the following steps:

[0020] Step 3.1: Build a simulated fire source device, wherein the simulated fire source device includes a remote ignition control device, and the power of the simulated fire source device is adjustable;

[0021] Step 3.2: Build a cable support suitable for the size of the over-temperature test sample;

[0022] Step 3.3: Place the over-temperature test sample on the cable support, arrange the simulated fire source device at the center position directly below the over-temperature test sample to obtain an over-temperature test platform, and completely cover the over-temperature test platform with a high-temperature resistant box.

[0023] Optionally, in step 4, the over-temperature test sample is subjected to an over-temperature test, and the temperature data of each thermocouple of the over-temperature test sample during over-temperature is recorded, including the following steps:

[0024] Step 4.1: Set the initial temperature of the test sample to T3, the relative humidity of the environment to be between 30% and 70%, implement remote ignition, and adjust the power of the simulated fire source device to simulate the state of the cable material on fire;

[0025] Step 4.2: After remote ignition, start the temperature measurement and collection system, record the temperature data of each thermocouple of each layer of the over-temperature test sample during the over-temperature test until the temperature at the bottom of the over-temperature test sample reaches T4, turn off the simulated fire source device, and repeat the over-temperature test multiple times.

[0026] Optionally, in step 5, the thermal conductivity of the cable material at different temperatures is determined according to the thermal capacity values of the outer sheath and insulation layer of the first cable material at different temperatures obtained in step 1 and the temperature data of each thermocouple of the over-temperature test sample during over-temperature obtained in step 4, including the following steps:

[0027] Step 5.1: According to the heat flux calculation formula: Q = C pQm(T-T0) / (txA), the heat flux density of the outer sheath and the insulation layer of the cable material at different temperatures is calculated, wherein Q represents the heat flux density vector flowing through the thickness direction of the sample, m represents the mass of the outer sheath or the insulation layer, T represents the temperature of the over-temperature test sample to the fire surface during the over-temperature test, T0 represents the initial temperature of the over-temperature test sample before the over-temperature test, t represents the time for the surface temperature of the over-temperature test sample to rise to T, A represents the surface area of the over-temperature test sample, and T and T0 are measured by the thermocouples arranged on the outer sheath and the insulation layer of the second cable material; p represents the heat capacity value, m represents the mass of the outer sheath or the insulation layer, T represents the temperature of the over-temperature test sample to the fire surface during the over-temperature test, T0 represents the initial temperature of the over-temperature test sample before the over-temperature test, t represents the time for the surface temperature of the over-temperature test sample to rise to T, A represents the surface area of the over-temperature test sample, and T and T0 are measured by the thermocouples arranged on the outer sheath and the insulation layer of the second cable material;

[0028] Step 5.2: According to the Fourier heat conduction law formula: Every T5, the thermal conductivity of the outer sheath and the insulation layer of the cable material at different temperatures is recorded, wherein Q represents the heat flux density vector flowing through the thickness direction of the over-temperature test sample, L represents the thickness of the outer sheath or the insulation layer of the cable material, T1 represents the temperature of the over-temperature test sample to the fire surface during the over-temperature test, T2 represents the temperature of the over-temperature test sample away from the fire surface during the over-temperature test, and T1 and T2 are measured by the thermocouples arranged on the outer sheath and the insulation layer of the second cable material.

[0029] Step 6: According to the thermal conductivity of the cable material at different temperatures, the thermal conductivity mutation point of the cable material is determined, and the thermal conductivity of the cable material before, after and during the mutation is nonlinearly fitted to obtain a curve of the thermal conductivity of the cable material changing with temperature.

[0030] According to another aspect of the embodiment of the present application, a fitting device for the thermal conductivity coefficient of cable material under fire high temperature is provided, comprising:

[0031] The first determining module is configured to prepare two cable materials, press the outer sheath and the insulation layer of the first cable material into a sheet with uniform thickness, and perform differential scanning calorimetry on the outer sheath and the insulation layer of the first cable material to determine the heat capacity values of the outer sheath and the insulation layer of the first cable material at different temperatures.

[0032] The manufacturing module is configured to press the outer sheath and the insulation layer of the second cable material into a sheet with uniform thickness, uniformly arrange multiple thermocouples on the outer sheath and the insulation layer of the second cable material, and manufacture the over-temperature test sample in a stacked structure through a high-temperature pressing process.

[0033] The test platform building module is configured to build an over-temperature test platform, wherein the over-temperature test platform comprises a simulated fire source device, a cable support, and a high-temperature resistant box.

[0034] The over-temperature test module is used for over-temperature test on the over-temperature test sample, and records the temperature data of each thermocouple of the over-temperature test sample when over-temperature;

[0035] The second determining module is used for determining the thermal conductivity coefficient of the cable material at different temperatures according to the thermal capacity values of the outer sheath and the insulation layer of the first cable material at different temperatures obtained in step 1 and the temperature data of each thermocouple of the over-temperature test sample when over-temperature obtained in step 4.

[0036] The fitting module is used for determining the thermal conductivity coefficient mutation point of the cable material according to the thermal conductivity coefficient of the cable material at different temperatures, and performing non-linear fitting on the thermal conductivity coefficient of the cable material before, after and during the mutation, respectively, to obtain a curve graph of the thermal conductivity coefficient of the cable material changing with temperature.

[0037] According to another aspect of the embodiment of the present application, a non-volatile storage medium is provided, which stores a plurality of instructions adapted to be loaded and executed by a processor to implement any one of the fitting methods of the thermal conductivity coefficient of the cable material under the high temperature of fire.

[0038] According to another aspect of the embodiment of the present application, an electronic device is provided, which includes one or more processors and a memory for storing one or more programs, wherein when the one or more programs are executed by the one or more processors, the one or more processors implement any one of the fitting methods of the thermal conductivity coefficient of the cable material under the high temperature of fire.

[0039] According to still another aspect of the embodiment of the present application, a computer program product is provided, which includes a computer program, and the computer program is executed by a processor to implement any one of the fitting methods of the thermal conductivity coefficient of the cable material under the high temperature of fire.

[0040] In the embodiment of the present application, a fitting method of the thermal conductivity coefficient of the cable material under the high temperature of fire is provided, and the present application has the following advantages:

[0041] (1) General research considers the thermal conductivity coefficient of the material under normal working condition, and most of the researches are set as fixed values. However, the cable tunnel is a special occasion, and the accurate thermal conductivity coefficients of different layers of materials are needed to analyze the temperature rise in the multi-layer cable under the high-temperature environment of fire. However, the temperature under the fire environment may be much higher than the normal working temperature, and the phase change of the material may occur, so that the thermal conductivity coefficient will change greatly, resulting in large error of the calculation result. The present application combines the test data before, after and during the mutation of the cable material to carry out nonlinear fitting of the thermal conductivity coefficient, and obtains the curve graph of the thermal conductivity coefficient of the cable material changing with temperature. The purpose of using the thermal conductivity coefficient changing with time more in line with the actual situation for cable fire simulation is achieved, and the technical problem that the fixed thermal conductivity coefficient cannot accurately simulate the real situation of cable fire is solved.

[0042] (2) At present, the main methods for measuring the thermal conductivity coefficient of materials are hot-wire method, laser flash method and transient plane measurement method. However, most of them can only measure the thermal conductivity coefficient at a certain temperature, and the sample size and structure and the physical form of the material are often limited during measurement, and the measurement conditions are relatively complicated. The present application first measures the heat capacity value of the cable material sample at different temperatures by using the differential scanning calorimeter with higher universality, then simulates the internal structure of the cable to press the cable material into a multi-layer structure sample for temperature rise test, combines the temperature data between layers obtained by the over-temperature test of simulated fire, and calculates the thermal conductivity coefficient of the cable material sample at different temperatures by using the corresponding formula and fitting. The obtained result is more in line with the actual situation. BRIEF DESCRIPTION OF DRAWINGS

[0043] The drawings described herein are used to provide further understanding of the present application, constitute a part of the present application, and the schematic embodiments of the present application and their descriptions are used to explain the present application, and do not constitute an improper limitation on the present application. In the drawings:

[0044] Figure 1 It is a fitting method flow chart of the thermal conductivity coefficient of the cable material under the fire high-temperature condition according to the embodiment of the present application;

[0045] Figure 2 It is a schematic diagram of an optional over-temperature test sample preparation method according to the embodiment of the present application;

[0046] Figure 3 It is a schematic diagram of an optional over-temperature test platform according to the embodiment of the present application;

[0047] Figure 4 It is a schematic diagram of an optional nonlinear fitting of the thermal conductivity coefficient of the cable material according to the embodiment of the present application;

[0048] Figure 5is a schematic view of a fitting device for thermal conductivity coefficient of cable material under fire high temperature according to an embodiment of the present application;

[0049] Figure 6 is a schematic view of an electronic device according to an embodiment of the present application. DETAILED DESCRIPTION

[0050] In order to make the personnel in the technical field better understand the present application scheme, the technical scheme in the embodiment of the present application will be described clearly and completely below in combination with the drawings in the embodiment of the present application. Obviously, the described embodiment is only a part of the embodiment of the present application, not all. Based on the embodiment in the present application, all other embodiments obtained by the person skilled in the art without creative labor should belong to the protection scope of the present application.

[0051] It should be noted that the terms "first", "second" and the like in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily indicate a specific order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device including a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0052] According to an embodiment of the present application, a fitting method embodiment for thermal conductivity coefficient of cable material under fire high temperature is provided. It should be noted that the steps shown in the flowchart of the drawings can be executed in a computer system such as a set of computer executable instructions, and although the logical order is shown in the flowchart, in some cases, the steps shown or described herein can be executed in an order different from that shown herein.

[0053] Figure 1 is a fitting method flowchart for thermal conductivity coefficient of cable material under fire high temperature according to an embodiment of the present application, as shown in Figure 1 The method comprises the following steps:

[0054] Step 1: Prepare two cable materials, press the outer sheath and insulation layer of the first cable material into a sheet with uniform thickness, and respectively perform differential scanning calorimetry test on the outer sheath and insulation layer of the first cable material to determine the respective heat capacity values of the outer sheath and insulation layer of the first cable material at different temperatures;

[0055] In this step, because specific stabilizers, plasticizers, calcium carbonate and other inorganic fillers and additives are added to the outer sheath of the cable, in order to better determine the heat capacity values of the outer sheath and the insulation layer of the cable material at different temperatures, a sample made of real cable material is used to perform differential scanning calorimetry test. Differential scanning calorimetry (DSC) is a commonly used thermal analysis technique for studying the thermal properties of a substance, such as melting temperature, crystallization temperature, glass transition temperature, etc. In differential scanning calorimetry test, the sample and the reference are heated simultaneously, and the temperature difference between them is measured to obtain the heat flow-temperature curve of the sample. According to the heat flow-temperature curve of the sample, the heat capacity value of the sample can be determined.

[0056] In an alternative embodiment, in step 1, two portions of cable material are prepared, the outer sheath and the insulation layer of the first portion of cable material are pressed into a sheet with uniform thickness, and differential scanning calorimetry test is performed on the outer sheath and the insulation layer of the first portion of cable material respectively to determine the heat capacity values of the outer sheath and the insulation layer of the first portion of cable material at different temperatures, including the following steps:

[0057] Step 1.1: Divide the real cable material into two portions, and press the outer sheath and the insulation layer of the first portion of cable material into a sheet with uniform thickness;

[0058] Step 1.2: Perform differential scanning calorimetry test on the outer sheath and the insulation layer of the first portion of cable material respectively to obtain the heat flow-temperature curve, wherein the differential scanning calorimetry test is performed in a nitrogen atmosphere, the gas flow rate is set to V1, the temperature is set from T1 to T2, and the heating rate is β;

[0059] Step 1.3: According to the heat capacity formula: the heat capacity values of the outer sheath and the insulation layer at different temperatures are obtained, wherein C p represents the heat capacity value, ΔH represents the heat flow per unit time on the heat flow-temperature curve, and m represents the mass of the outer sheath or the insulation layer.

[0060] Optionally, a test sample is made of real cable, and the outer sheath and the insulation layer of the real cable are pressed into a sheet with uniform thickness. The outer sheath and the insulation layer of the cable material with a mass of 5 mg can be selected for differential scanning calorimetry test. The test is performed in a nitrogen atmosphere, the gas flow rate is 50 mL / min, the test temperature is set from 25°C to 180°C, and the heating rate is 10°C / min. After the test, the heat flow-temperature (DSC) curve is drawn, and the heat capacity values of the cable layer material at different temperatures C p are calculated. For example, the heat capacity values of the insulation layer of the cable material at different temperatures are as shown in the following table:

[0061]

[0062] Step 2: Press the outer sheath and insulation layer of the second cable material into a sheet of uniform thickness, and evenly arrange multiple thermocouples on the outer sheath and insulation layer of the second cable material, and make it into a stacked test sample through a high-temperature pressing process;

[0063] In this step, to ensure the accuracy of the over-temperature test, the over-temperature test sample is also made using real cable material. The outer sheath and insulation layer of the real cable material are pressed into sheets, and multiple thermocouples are evenly arranged in each layer. Both the outer sheath and insulation layer are square, and 3*3 thermocouples are arranged on both the outer sheath and insulation layer. Multiple sheets of the outer sheath and insulation layer with thermocouples are cross-stacked and pressed into one piece by a high-temperature pressing process to obtain the over-temperature test sample.

[0064] In an optional embodiment, in step 2, the outer sheath and insulation layer of the second cable material are pressed into a sheet of uniform thickness, and multiple thermocouples are uniformly arranged on the outer sheath and insulation layer of the second cable material. The sample is then fabricated into a stacked over-temperature test sample using a high-temperature pressing process, including the following steps:

[0065] Step 2.1: Press the outer sheath and insulation layer of the second cable material into a sheet of uniform thickness, and arrange multiple thermocouples of the same type evenly in an array on the outer sheath and insulation layer of the second cable material.

[0066] Step 2.2: The outer sheath and insulation layer of the second cable material, which contains multiple thermocouples of the same type, are pressed together by a high-temperature pressing process to obtain an over-temperature test sample.

[0067] Optional, such as Figure 2 As shown, test samples were made using real cables. The outer sheath and insulation material of the real cable were pressed into sheets of uniform thickness, with dimensions of 25cm×25cm×1cm. Nine K-type thermocouples were arranged in an array on the outer sheath and insulation. The temperature acquisition range of the thermocouples was -20 to 500℃, and the thickness was only 0.15mm. The outer sheath and insulation were cross-stacked and pressed together at high temperature to form a whole. Finally, glass fiber heat insulation boards were added to both sides of the sample.

[0068] Step 3: Construct an over-temperature test platform, which includes a simulated fire source device, cable supports, and a high-temperature resistant chamber;

[0069] In this step, the simulated fire source device includes a combustion disc for placing the over-temperature test sample, and further includes a gas supply system composed of a butane gas cylinder, an adjustable flow valve, a gas supply pipeline and the like, and a remote ignition control device. The flow rate of butane gas output by the cylinder can be adjusted by adjusting the flow valve, so that the power of the fire source can be controlled. Considering that the external environment may interfere with the test results, a high-temperature-resistant iron box with appropriate size is used, and the platform is covered after the entire test platform is built.

[0070] In an alternative embodiment, in step 3, the over-temperature test platform is built, wherein the over-temperature test platform is built to include a simulated fire source device, a cable support, a high-temperature-resistant box, and the like, including the following steps:

[0071] Step 3.1: Building a simulated fire source device, wherein the simulated fire source device includes a remote ignition control device, and the power of the simulated fire source device is adjustable;

[0072] Step 3.2: A cable support suitable for the size of the over-temperature test sample;

[0073] Step 3.3: Placing the over-temperature test sample on the cable support, arranging the simulated fire source device at the center position directly below the over-temperature test sample, obtaining the over-temperature test platform, and completely covering the over-temperature test platform with the high-temperature-resistant box.

[0074] Alternatively, the over-temperature test platform is built to include a simulated fire source device, a cable support, a high-temperature-resistant box and the like, as shown in Figure 3 The over-temperature test sample to be tested is placed on a specially designed cable support with a size of 20cm×20cm×60cm, and a simulated fire source device with a size of 10cm×15cm, a vertical distance of 30cm from the bottom of the sample, and a fire source power of 1kW is arranged directly below the middle of the cable sample to heat the test sample. A high-temperature-resistant box with a size of 90cm×90cm×100cm is used to cover the test platform, so as to isolate the test platform from the external environment.

[0075] Step 4: Over-temperature test is performed on the over-temperature test sample, and the temperature data of each thermocouple of the over-temperature test sample during over-temperature is recorded;

[0076] In this step, the over-temperature test is performed on the over-temperature test sample to simulate the actual temperature condition of the cable tunnel during a fire, and the temperature data of each thermocouple of the over-temperature test sample during over-temperature is recorded.

[0077] In an alternative embodiment, in step 4, the over-temperature test is performed on the over-temperature test sample, and the temperature data of each thermocouple of the over-temperature test sample during over-temperature is recorded, including the following steps:

[0078] Step 4.1: Set the initial temperature of the test sample to T3, the relative humidity of the environment to be between 30% and 70%, implement remote ignition, and adjust the power of the simulated fire source device to simulate the state of the cable material on fire;

[0079] Step 4.2: After remote ignition, start the temperature measurement and collection system, record the temperature data of each layer of the over-temperature test sample during the over-temperature test, and stop the simulated fire source device when the temperature at the bottom of the over-temperature test sample reaches T4, and repeat the over-temperature test multiple times. Optionally, the cable material over-temperature test is performed on the test sample, the initial temperature of the over-temperature test sample is 25℃, and the relative humidity of the environment is about 50%. Implement remote ignition, and start the temperature measurement and collection system to record the temperature distribution and change of each thermocouple between the layers of the test sample during the test, until the temperature at the bottom of the test sample (the fire surface) reaches 250℃, stop the test, and repeat the test multiple times.

[0080] Step 5: Determine the thermal conductivity of the cable material at different temperatures based on the thermal capacity values of the outer sheath and insulation layer of the first cable material at different temperatures obtained in step 1, and the temperature data of the multiple thermocouples during the over-temperature test obtained in step 4.

[0081] In this step, the heat flux density at the corresponding position of the thermocouple of each layer of the cable material at different temperatures is calculated according to the heat flux density calculation formula, and the thermal conductivity of the cable outer sheath and cable insulation layer material at the corresponding position of the thermocouple is recorded every interval of the same temperature according to the Fourier heat conduction law formula.

[0082] In an alternative embodiment, in step 5, the thermal conductivity of the cable material at different temperatures is determined based on the thermal capacity values of the outer sheath and insulation layer of the first cable material at different temperatures obtained in step 1, and the temperature data of the multiple thermocouples during the over-temperature test obtained in step 4, including the following steps:

[0083] Step 5.1: Calculate the heat flux density of the outer sheath and insulation layer of the cable material at different temperatures according to the heat flux density calculation formula: Q = C p × m × (T - T0) / (t × A), where Q represents the heat flux density vector in the thickness direction of the sample, C p represents the heat capacity value, m represents the mass of the outer sheath or insulation layer, T represents the temperature of the over-temperature test sample towards the fire surface during the over-temperature test, T0 represents the initial temperature of the over-temperature test sample before the over-temperature test, t represents the time for the surface temperature of the over-temperature test sample to rise to T, A represents the surface area of the over-temperature test sample, and T and T0 are measured by the thermocouples arranged on the outer sheath and insulation layer of the second cable material;

[0084] Step 5.2: According to the Fourier heat conduction law formula: Every T5, record the thermal conductivity of the outer sheath and insulation layer of the cable material at different temperatures, wherein Q represents the heat flow density vector flowing through the thickness direction of the overtemperature test sample, L represents the thickness of the outer sheath or insulation layer of the cable material, T1 represents the temperature of the overtemperature test sample facing the fire in the overtemperature test, and T2 represents the temperature of the overtemperature test sample away from the fire in the overtemperature test. T1 and T2 are measured by the thermocouples arranged on the outer sheath and insulation layer of the second cable material.

[0085] Optionally, according to the thermal capacity values of the outer sheath and insulation layer of the real cable material at different temperatures obtained in step 1 and the temperature data of the plurality of thermocouples of the overtemperature test sample of the real cable material at overtemperature obtained in step 4, the heat flow density of each layer of the real cable material at different temperatures is calculated by the heat flow density calculation formula, and the thermal conductivity of the cable outer sheath and insulation layer material at different positions is calculated every 10℃ according to the Fourier heat conduction law formula.

[0086] Step 6: According to the thermal conductivity of the cable material at different temperatures, determine the thermal conductivity mutation point of the cable material, and perform nonlinear fitting on the thermal conductivity of the cable material before and after the mutation and during the mutation process, respectively, to obtain a curve graph of the thermal conductivity of the cable material changing with temperature.

[0087] In this step, it is considered that the phase change does not occur instantaneously, but gradually in a temperature interval. Find the thermal conductivity mutation point (identify the point where the thermal conductivity decreases or increases, which usually corresponds to the beginning or end of the phase change), and determine the temperature interval of the phase change of the cable material based on this. For example, it is determined that the phase change temperature interval of the cable insulation material is 120℃-150℃, and the fluid state of the cable insulation appears in this temperature range. The thermal conductivities before, during and after the phase change of the cable material show different trends, and the thermal conductivities are segmented and polynomial nonlinearly fitted, and finally a curve graph of the thermal conductivity of the cable material changing with temperature is obtained. The fitting formulas in the three intervals before, during and after the phase change of the cable insulation are respectively:

[0088] y1 = -4.62963 x 10-8x3 + 1.86923 x 10-5x2 - 5.13561 x 10-5x + 0.2029, 25℃≤x≤105℃, y2 = -1.66667 x 10-7x3 + 3.60714 x 10-5x2 + 0.00386x - 0.31047, 105℃≤x≤145℃,

[0089] y3 = -3.2571410-6x3 + 0.00156x2 - 0.24803x + 13.49946, 145℃≤x≤180℃.

[0090] Due to the count discontinuity at the breaking point, the function is smoothed as shown in the following formula: Figure 4 The thermal conductivity of the cable insulation material changes with temperature.

[0091] In the embodiment of the present application, by the above-mentioned step 1: preparing two cable materials, the outer sheath and the insulation layer of the first cable material are pressed into a sheet with uniform thickness, and the differential scanning calorimetry test is performed on the outer sheath and the insulation layer of the first cable material respectively to determine the heat capacity values of the outer sheath and the insulation layer of the first cable material at different temperatures; step 2: the outer sheath and the insulation layer of the second cable material are pressed into a sheet with uniform thickness, and a plurality of thermocouples are arranged uniformly on the outer sheath and the insulation layer of the second cable material, and a stacked structure over-temperature test sample is made by a high-temperature pressing process; step 3: building an over-temperature test platform, wherein the over-temperature test platform includes a simulated fire source device, a cable support, and a high-temperature resistant box; step 4: performing an over-temperature test on the over-temperature test sample, and recording the temperature data of each of the plurality of thermocouples when the over-temperature test sample is over-temperature; step 5: determining the thermal conductivity of the cable material at different temperatures according to the heat capacity values of the outer sheath and the insulation layer of the first cable material at different temperatures obtained in step 1 and the temperature data of each of the plurality of thermocouples of the over-temperature test sample when over-temperature obtained in step 4; step 6: determining the thermal conductivity mutation point of the cable material according to the thermal conductivity of the cable material at different temperatures, and performing nonlinear fitting on the thermal conductivity of the cable material before and after the mutation and in the process of the mutation respectively to obtain a curve graph of the thermal conductivity of the cable material changing with temperature. The purpose of using the thermal conductivity changing with time more in line with the actual situation to simulate the cable fire is achieved, the technical problem that the fixed thermal conductivity cannot accurately simulate the real situation of the cable fire is solved, and the technical effect of improving the accuracy of the cable fire simulation is achieved.

[0092] Based on the above embodiment and optional embodiment, an optional implementation manner of the present application is provided:

[0093] Step S1: using a real cable to make a test sample, the outer sheath and the insulation layer material of the real cable are pressed into a sheet with uniform thickness, and the differential scanning calorimetry test can be performed on the outer sheath and the insulation layer of the cable material with a mass of 5 mg. The test is performed in a nitrogen atmosphere, the gas flow rate is 50 mL / min, the test temperature is set from 25℃ to 180℃, and the heating rate is 10℃ / min. After the test, the heat flow-temperature (DSC) curve is drawn, and the heat capacity values C p , of the insulation layer of the cable material at different temperatures are as shown in the following table:

[0094]

[0095] Step S2: As shown in Figure 2 , a test sample is made using a real cable, and the outer sheath and insulation layer materials of the real cable are pressed into a sheet with uniform thickness, which can be 25 cm x 25 cm x 1 cm. Nine K-type thermocouples are arranged in an array manner in the outer sheath and insulation layer, and the temperature acquisition range of the thermocouples is -20-500℃, and the thickness is only 0.15 mm. The outer sheath and insulation layer are cross-stacked and synthesized into a whole by high-temperature pressing, and finally glass fiber heat insulation plates are installed on both sides of the test sample.

[0096] Step S3: Build an over-temperature test platform, including a simulated fire source device, a cable support, a high-temperature resistant box and other test equipment, as shown in Figure 3 , the over-temperature test sample to be tested is placed on a specially-made cable support with a size of 20 cm x 20 cm x 60 cm, and a simulated fire source device with a size of 10 cm x 15 cm is arranged directly below the middle of the cable sample, with a vertical distance of 30 cm from the bottom of the sample and a fire source power of 1 kW to heat the test sample. A 90 cm x 90 cm x 100 cm high-temperature resistant box is used to cover the test platform, and the test platform is isolated from the external environment.

[0097] Step S4: Perform cable material over-temperature test on the over-temperature test sample to be tested, and the initial temperature of the over-temperature test sample is 25℃, and the relative humidity of the environment is about 50%. Implement remote ignition, and simultaneously start the temperature measurement and collection system to record the temperature distribution and change of each thermocouple between the sample layers during the test, until the temperature of the bottom of the test sample (the fire surface) reaches 250℃, the test is stopped, and the test is repeated multiple times.

[0098] Step S5: According to the heat capacity values of the outer sheath and insulation layer of the real cable material at different temperatures obtained in step S1 and the temperature data of the multiple thermocouples of the over-temperature test sample of the real cable material obtained in step S4, the heat flow density of each layer of the real cable material at different temperatures is calculated by the heat flow density calculation formula, and the thermal conductivity of the cable outer sheath and insulation layer material at different positions is calculated every 10℃ according to the Fourier heat conduction law.

[0099] Step S6: Considering that phase transition does not occur instantaneously, but gradually in a temperature interval. Find the inflection point of the thermal conductivity (identify the point where the thermal conductivity decreases or increases, which usually corresponds to the beginning or end of the phase transition), based on this, and determine the temperature interval of the phase transition of the cable material. For example, it is determined that the phase transition temperature interval of the cable insulation material is 120℃-150℃, and the fluid state of the cable insulation appears in this temperature range. The thermal conductivity of the cable material before, during and after the phase transition presents different trends, and the thermal conductivity is fitted by a segmented polynomial nonlinear function, and finally the curve of the thermal conductivity of the cable material with temperature is obtained. The fitting formulas in the three intervals before, during and after the phase transition of the cable insulation are respectively:

[0100] y1 = -4.62963 x 10 -8 x 3 + 1.86923 x 10 -5 x 2 - 5.13561 x 10 -5 x + 0.2029, 25℃≤x≤105℃,

[0101] y2 = -1.66667 x 10 -7 x 3 + 3.60714 x 10 -5 x 2 + 0.00386x - 0.31047, 105℃≤x≤145℃,

[0102] y3 = -3.25714 x 10 -6 x 3 + 0.00156x 2 - 0.24803x + 13.49946, 145℃≤x≤180℃.

[0103] Due to the reciprocal discontinuity at the breaking point, the above function is smoothed, and the thermal conductivity of the cable insulation material with temperature change is shown as Figure 4 .

[0104] The above optional implementation at least achieves the following effects: the purpose of using a more realistic time-varying thermal conductivity for cable fire simulation is achieved, the technical problem that the real situation of cable fire cannot be accurately simulated using a fixed thermal conductivity is solved, and the technical effect of improving the accuracy of cable fire simulation is achieved.

[0105] It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and although the logical order is shown in the flowchart, in some cases, the steps shown or described herein can be executed in an order different from that shown.

[0106] According to the embodiment of the present application, a device for implementing a fitting method of thermal conductivity of cable material under high temperature fire is also provided, Figure 5 A schematic diagram of a cable fire simulation device according to an embodiment of the present application is shown in Figure 5 The above-mentioned cable fire simulation device includes a first determination module 51, a production module 52, a test platform building module 53, an over-temperature test module 54, a second determination module 55, a fitting module 56, and the device will be described below.

[0107] The first determination module 51 is configured to prepare two portions of cable materials, compress the outer sheath and the insulation layer of the first portion of the cable materials into a sheet with uniform thickness, and perform differential scanning calorimetry test on the outer sheath and the insulation layer of the first portion of the cable materials respectively, to determine the heat capacity values of the outer sheath and the insulation layer of the first portion of the cable materials at different temperatures respectively.

[0108] The manufacturing module 52 is connected with the first determination module 51, and is configured to compress the outer sheath and the insulation layer of the second portion of the cable materials into a sheet with uniform thickness, arrange multiple thermocouples on the outer sheath and the insulation layer of the second portion of the cable materials, and manufacture the over-temperature test sample in a stacked structure through a high-temperature compression process.

[0109] The test platform building module 53 is connected with the manufacturing module 52, and is configured to build an over-temperature test platform, wherein the over-temperature test platform comprises a simulated fire source device, a cable support, and a high-temperature resistant box.

[0110] The over-temperature test module 54 is connected with the test platform building module 53, and is configured to perform over-temperature test on the over-temperature test sample, and record the temperature data of the multiple thermocouples of the over-temperature test sample at different temperatures.

[0111] The second determination module 55 is connected with the over-temperature test module 54, and is configured to determine the thermal conductivity of the cable materials at different temperatures according to the heat capacity values of the outer sheath and the insulation layer of the first portion of the cable materials at different temperatures obtained in step 1 and the temperature data of the multiple thermocouples of the over-temperature test sample at different temperatures obtained in step 4.

[0112] The fitting module 56 is connected with the second determination module 55, and is configured to determine the thermal conductivity mutation point of the cable materials according to the thermal conductivity of the cable materials at different temperatures, and perform nonlinear fitting on the thermal conductivity of the cable materials before, after and during the mutation respectively, to obtain a curve graph of the thermal conductivity of the cable materials changing with temperature.

[0113] The fitting method for the thermal conductivity coefficient of the cable material under the fire high temperature condition provided by the embodiment of the present application comprises the following steps: a first determining module is arranged to prepare two portions of cable materials, the outer sheath and the insulation layer of the first portion of the cable materials are pressed into a sheet shape with uniform thickness, and differential scanning calorimetry tests are respectively performed on the outer sheath and the insulation layer of the first portion of the cable materials to determine the heat capacity values of the outer sheath and the insulation layer of the first portion of the cable materials at different temperatures; a manufacturing module is arranged to press the outer sheath and the insulation layer of the second portion of the cable materials into a sheet shape with uniform thickness, to uniformly arrange a plurality of thermocouples on the outer sheath and the insulation layer of the second portion of the cable materials, and to manufacture the over-temperature test sample in a stacked structure through a high-temperature pressing process; a test platform building module is arranged to build an over-temperature test platform, wherein the over-temperature test platform comprises a simulated fire source device, a cable support and a high-temperature resistant box; an over-temperature test module is arranged to perform an over-temperature test on the over-temperature test sample and to record the temperature data of the plurality of thermocouples of the over-temperature test sample at the time of over-temperature; a second determining module is arranged to determine the thermal conductivity coefficient of the cable material at different temperatures according to the heat capacity values of the outer sheath and the insulation layer of the first portion of the cable materials at different temperatures obtained in step 1 and the temperature data of the plurality of thermocouples of the over-temperature test sample at the time of over-temperature obtained in step 4; and a fitting module is arranged to determine the thermal conductivity coefficient mutation point of the cable material according to the thermal conductivity coefficient of the cable material at different temperatures, to perform nonlinear fitting on the thermal conductivity coefficient of the cable material before and after the mutation and in the mutation process, respectively, and to obtain a curve graph of the thermal conductivity coefficient of the cable material changing with temperature. The purpose of using the thermal conductivity coefficient changing with time which is more in line with the actual situation to simulate the cable fire is achieved, the technical problem that the real situation of the cable fire cannot be accurately simulated by using the fixed thermal conductivity coefficient is solved, and the technical effect of improving the accuracy of the cable fire simulation is achieved.

[0114] It should be noted that each of the above modules can be implemented by software or hardware. For example, for the latter, each of the above modules can be located in the same processor, or any combination of the above modules can be located in different processors.

[0115] It should be noted that the above first determining module 51, manufacturing module 52, test platform building module 53, over-temperature test module 54, second determining module 55 and fitting module 56 correspond to steps 1 to 6 in the embodiment, and the above modules have the same instances and application scenarios as the corresponding steps, but are not limited to the contents disclosed in the above embodiment. It should be noted that the above modules can run in a computer terminal as a device.

[0116] It should be noted that the optional or preferred embodiments of the present embodiment can refer to the related description in the embodiment, which will not be repeated here.

[0117] The simulation device of the cable fire can also include a processor and a memory, the first determining module 51, the manufacturing module 52, the test platform building module 53, the over-temperature test module 54, the second determining module 55, the fitting module 56 and the like are stored in the memory as program units, and the corresponding functions are realized by the processor executing the program units stored in the memory.

[0118] The processor contains a core, and the core calls the corresponding program units in the memory. The core can be provided with one or more. The memory can include a non-permanent memory in a computer readable medium, a random access memory (RAM) and / or a non-volatile memory such as a read-only memory (ROM) or a flash memory (flash RAM), and the memory includes at least one memory chip.

[0119] The embodiment of the present application provides a non-volatile storage medium, which stores a program, and the program is executed by a processor to realize a fitting method of a thermal conductivity coefficient of a cable material under a fire high-temperature condition.

[0120] As Figure 6 The embodiment of the present application provides an electronic device, and the electronic device 10 includes a processor, a memory, and a program stored in the memory and executable on the processor. When the processor executes the program, the following steps are realized: the memory is used for storing a computer program, wherein when the computer program is executed by the processor, the processor realizes the fitting method of the thermal conductivity coefficient of the cable material under the fire high-temperature condition. The device in the present application can be a server, a PC or the like.

[0121] The present application also provides a computer program product, when executed on a data processing device, is suitable for executing the program initialized with the following method steps: the computer instructions are executed by the processor to execute the fitting method of the thermal conductivity coefficient of the cable material under the fire high-temperature condition.

[0122] Those skilled in the art should understand that the embodiments of the present application can be provided as a method, a system or a computer program product. Therefore, the present application can be in the form of a complete hardware embodiment, a complete software embodiment or an embodiment combining software and hardware aspects. Moreover, the present application can be in the form of a computer program product implemented on one or more computer usable storage media containing computer usable program codes (including but not limited to disk storage, CD-ROM, optical storage, etc.).

[0123] The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. Figure 1 one or more flow or blocks Figure 1 means for functionally implementing the steps in the flowchart block or blocks

[0124] These computer program instructions can also be stored in a computer readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer readable memory produce an article of manufacture including instructions which implement the function specified in the flowchart block or blocks. Figure 1 one or more flow or blocks Figure 1 means for functionally implementing the steps in the flowchart block or blocks

[0125] The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. Figure 1 one or more flow or blocks Figure 1 means for functionally implementing the steps in the flowchart block or blocks

[0126] In one typical configuration, the computing device includes one or more processors (CPUs), input / output interfaces, network interfaces, and memory.

[0127] The memory can include non-persistent memory and / or volatile memory, such as random access memory (RAM) and / or cache memory, for storing instructions and data. The memory can also include non-volatile memory, such as read only memory (ROM), electrically programmable read only memory (EPROM), electrically erasable programmable read only memory (EEPROM), flash memory, or other non-volatile memory. The memory can be a memory of a computer-readable medium.

[0128] Computer-readable media includes permanent and non-permanent, movable and non-movable media that can be implemented by any method or technology to store information. The information can be computer-readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, compact disc read-only memory (CD-ROM), digital versatile disc (DVD) or other optical storage, magnetic cassette, magnetic tape disk storage or other magnetic storage devices, or any other non-transmission medium that can be used to store information accessible by a computing device. According to the definition herein, computer-readable media does not include transitory media such as modulated data signals and carriers.

[0129] It should also be noted that the terms "comprising", "containing", or any other variant thereof are intended to cover a non-exclusive inclusion, such that a process, method, article or apparatus that comprises a list of elements does not only include those elements, but can also include other elements not expressly listed or inherent to such process, method, article or apparatus. Without more limitations, the element defined by the statement "comprising a" does not exclude the presence of additional identical elements in the process, method, article or apparatus that includes the element.

[0130] Those skilled in the art will appreciate that embodiments of the present application can be provided as a method, system or computer program product. Accordingly, the present application can take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application can take the form of a computer program product implemented on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROMs, optical storage devices, etc.) containing computer usable program code.

[0131] The above merely provides embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application shall be included in the scope of claims of the present application.

Claims

1. A method of fitting the thermal conductivity of cable materials under fire high temperature conditions, characterized in that, The method comprises the following steps: Step 1: two cable materials are prepared, the outer sheath and the insulation layer of the first cable material are pressed into a sheet with uniform thickness, and differential scanning calorimetry is performed on the outer sheath and the insulation layer of the first cable material respectively to determine the heat capacity values of the outer sheath and the insulation layer of the first cable material at different temperatures; Step 2: the outer sheath and the insulation layer of the second cable material are pressed into a sheet with uniform thickness, a plurality of thermocouples are uniformly arranged on the outer sheath and the insulation layer of the second cable material, and a stacked over-temperature test sample is prepared through a high-temperature pressing process; Step 3: an over-temperature test platform is built, wherein the over-temperature test platform comprises a simulated fire source device, a cable support, and a high-temperature resistant box; Step 4: over-temperature test is performed on the over-temperature test sample, and the temperature data of each thermocouple of the over-temperature test sample during over-temperature is recorded; Step 5: according to the heat capacity values of the outer sheath and the insulation layer of the first cable material at different temperatures obtained in step 1 and the temperature data of each thermocouple of the over-temperature test sample during over-temperature obtained in step 4, the thermal conductivity of the cable material at different temperatures is determined; Step 6: according to the thermal conductivity of the cable material at different temperatures, the thermal conductivity mutation point of the cable material is determined, and the thermal conductivities before, after and during the mutation of the cable material are nonlinearly fitted respectively to obtain a curve graph of the thermal conductivity of the cable material changing with temperature.

2. The method of claim 1, wherein, In step 1, two cable materials are prepared, the outer sheath and the insulation layer of the first cable material are pressed into a sheet with uniform thickness, and differential scanning calorimetry is performed on the outer sheath and the insulation layer of the first cable material respectively to determine the heat capacity values of the outer sheath and the insulation layer of the first cable material at different temperatures, which comprises the following steps: Step 1.1: two cable materials are prepared, and the outer sheath and the insulation layer of the first cable material are pressed into a sheet with uniform thickness; Step 1.2: differential scanning calorimetry is performed on the outer sheath and the insulation layer of the first cable material respectively to obtain a heat flow-temperature curve, wherein the differential scanning calorimetry is performed in a nitrogen atmosphere, the gas flow rate is set to V1, the temperature is from T1 to T2, and the heating rate is β; Step 1.3: Obtain the heat capacity values of the outer sheath and the insulation layer at different temperatures according to the heat capacity formula: , wherein C p represents the heat capacity value, m represents the mass of the outer sheath or the insulation layer, and t represents the temperature. represents the heat flow per unit time on the heat flow-temperature curve, and m represents the mass of the outer sheath or the insulation layer.

3. The method of claim 1, wherein, In step 2, the outer sheath and the insulation layer of the second cable material are pressed into a sheet with uniform thickness, a plurality of thermocouples are uniformly arranged on the outer sheath and the insulation layer of the second cable material, and a stacked over-temperature test sample is prepared through a high-temperature pressing process, which comprises the following steps: Step 2.1: the outer sheath and the insulation layer of the second cable material are pressed into a sheet with uniform thickness, and a plurality of thermocouples of the same type are uniformly arranged in an array on the outer sheath and the insulation layer of the second cable material respectively; Step 2.2: the outer sheath and the insulation layer of the second cable material with a plurality of thermocouples of the same type arranged thereon are pressed into one body through the high-temperature pressing process to obtain an over-temperature test sample.

4. The method of claim 1, wherein, In the step 3, a platform for over-temperature test is built, wherein the platform comprises a simulated fire source device, a cable support, a high-temperature resistant box, and the following steps: Step 3.1: building the simulated fire source device, wherein the simulated fire source device comprises a remote ignition control device, and the power of the simulated fire source device is adjustable; Step 3.2: building a cable support suitable for the size of the over-temperature test sample; Step 3.3: placing the over-temperature test sample on the cable support, arranging the simulated fire source device at the center position directly below the over-temperature test sample, obtaining the over-temperature test platform, and completely covering the over-temperature test platform with the high-temperature resistant box.

5. The method of claim 1, wherein, In the step 4, an over-temperature test is performed on the over-temperature test sample, and the temperature data of each thermocouple of the over-temperature test sample during over-temperature is recorded, including the following steps: Step 4.1: setting the initial temperature of the test sample as T3, the relative humidity of the environment between 30%-70%, implementing remote ignition, and adjusting the power of the simulated fire source device to simulate the state of the cable material on fire; Step 4.2: after remote ignition, starting the temperature measurement and collection system, recording the temperature data of each thermocouple of each layer of the over-temperature test sample during the over-temperature test, until the temperature of the bottom of the over-temperature test sample reaches T4, the simulated fire source device is turned off, and the over-temperature test is repeated multiple times.

6. The method of claim 1, wherein, In the step 5, the thermal conductivity coefficient of the cable material at different temperatures is determined according to the thermal capacity values of the outer sheath and the insulation layer of the first cable material at different temperatures obtained in the step 1, and the temperature data of each thermocouple of the over-temperature test sample during over-temperature obtained in the step 4, including the following steps: Step 5.1: Calculate heat flux of the outer sheath and the insulation layer of the cable material at different temperatures according to the heat flux formula: Q = mC (T - T0) / (t x A), wherein Q represents the heat flux vector flowing through the thickness direction of the sample, m represents the mass of the outer sheath or the insulation layer, C represents the heat capacity value, T represents the temperature of the over-temperature test sample to the fire surface during the over-temperature test, T0 represents the initial temperature of the over-temperature test sample before the over-temperature test, t represents the time for the surface temperature of the over-temperature test sample to rise to T, A represents the surface area of the over-temperature test sample, and T and T0 are measured by the thermocouples arranged on the outer sheath and the insulation layer of the second portion of the cable material. Q = mC (T - T0) / (t x A), wherein Q represents the heat flux vector flowing through the thickness direction of the sample, m represents the mass of the outer sheath or the insulation layer, C represents the heat capacity value, T represents the temperature of the over-temperature test sample to the fire surface during the over-temperature test, T0 represents the initial temperature of the over-temperature test sample before the over-temperature test, t represents the time for the surface temperature of the over-temperature test sample to rise to T, A represents the surface area of the over-temperature test sample, and T and T0 are measured by the thermocouples arranged on the outer sheath and the insulation layer of the second portion of the cable material. Step 5.2: According to the Fourier heat conduction law formula: Every T5, record the thermal conductivity of the outer sheath and insulation layer of the cable material at different temperatures, wherein Q represents the heat flux vector flowing through the thickness direction of the overtemperature test sample, L represents the thickness of the outer sheath or insulation layer of the cable material, T1 represents the temperature of the overtemperature test sample facing the fire surface in the overtemperature test, T2 represents the temperature of the overtemperature test sample away from the fire surface in the overtemperature test, and T1 and T2 are measured by the thermocouples arranged on the outer sheath and insulation layer of the second portion of the cable material.

7. A fitting device for thermal conductivity of cable materials in case of fire high temperature, characterized in that, A fitting method for determining the thermal conductivity coefficient of a cable material under a fire high-temperature condition according to any one of claims 1-6, comprising: A first determination module for preparing two cable materials, pressing the outer sheath and the insulation layer of the first cable material into a sheet shape with uniform thickness, and performing differential scanning calorimetry test on the outer sheath and the insulation layer of the first cable material to determine the thermal capacity values of the outer sheath and the insulation layer of the first cable material at different temperatures; A manufacturing module for pressing the outer sheath and the insulation layer of the second cable material into a sheet shape with uniform thickness, uniformly arranging a plurality of thermocouples on the outer sheath and the insulation layer of the second cable material, and manufacturing an over-temperature test sample with a stacked structure through a high-temperature pressing process; A test platform building module for building an over-temperature test platform, wherein the platform comprises a simulated fire source device, a cable support, and a high-temperature resistant box; An over-temperature test module for performing an over-temperature test on the over-temperature test sample, and recording the temperature data of each thermocouple of the over-temperature test sample during over-temperature; a second determining module, configured to determine the thermal conductivity coefficient of the cable material at different temperatures according to the thermal capacity values of the outer sheath and the insulation layer of the first cable material obtained in the step 1, and the temperature data of the plurality of thermocouples when the over-temperature test sample is over-temperature obtained in the step 4; a fitting module, configured to determine the thermal conductivity coefficient mutation point of the cable material according to the thermal conductivity coefficient of the cable material at different temperatures, and perform nonlinear fitting on the thermal conductivity coefficient of the cable material before, after and during the mutation respectively to obtain a curve diagram of the thermal conductivity coefficient of the cable material changing with temperature.

8. A non-volatile storage medium, comprising: The non-volatile storage medium stores a plurality of instructions, and the instructions are adapted to be loaded and executed by the processor to implement the fitting method of the thermal conductivity coefficient of the cable material in a fire high-temperature condition according to any one of claims 1 to 6.

9. An electronic device, comprising: comprise: one or more processors and a memory, the memory being configured to store one or more programs, wherein the one or more programs, when executed by the one or more processors, cause the one or more processors to implement the fitting method of the thermal conductivity coefficient of the cable material in a fire high-temperature condition according to any one of claims 1 to 6.

10. A computer program product comprising computer instructions, characterized in that, The computer instructions are executed by the processor to implement the fitting method of the thermal conductivity coefficient of the cable material in a fire high-temperature condition according to any one of claims 1 to 6.

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