Fitting method for heat conduction coefficient of cable material under fire disaster high-temperature condition

Abstract

The invention discloses a fitting method for a heat conduction coefficient of a cable material under a fire disaster high-temperature condition. The method comprises the following steps: preparing two parts of cable materials, and determining respective heat capacity values of an outer protective layer and an insulating layer of the first part of cable material at different temperatures; a plurality of thermocouples are uniformly arranged on the outer protective layer and the insulating layer of the second part of cable material, and an over-temperature test sample with a stacked structure is manufactured through a high-temperature pressing process; carrying out an over-temperature test, and recording respective temperature data of the plurality of thermocouples when the over-temperature test sample is over-temperature; determining heat conductivity coefficients of the cable material at different temperatures; according to the heat conductivity coefficients of the cable material at different temperatures, heat conductivity coefficient mutation points are determined, nonlinear fitting is conducted on the heat conductivity coefficients of the cable material before mutation, after mutation and in the mutation process, and a curve graph of the heat conductivity coefficients of the cable material changing along with the temperature is obtained. The technical problem that the real situation of a cable fire cannot be accurately simulated by using a fixed heat conductivity coefficient is solved.

Description

Technical Field

[0001] The invention relates to the field of cable joint fire risk assessment, and in particular to a method for fitting the thermal conductivity coefficient of a cable material under high temperature fire conditions. Background Art

[0002] With the growing demand for energy in modern society, the stable operation of the power system is of vital importance. As a key component for power transmission, the thermal performance of cables is crucial to the safety and stability of the system. Among the performance indicators of cables, thermal conductivity is a key parameter that affects the heat distribution and heat dissipation effect of cables during normal operation. In the high temperature environment of a fire, the sheath structure materials such as the cable sheath and insulation will be affected by heat and undergo pyrolysis reactions, causing changes in their internal molecular structures and phase changes in the cable structure, from a normal state to a molten state. The molten state continues to undergo pyrolysis, producing substances such as carbides and combustible gases, which causes changes in the thermal conductivity of the cable material, posing a challenge to the safety of the cable system.

[0003] In the fire simulation model of related technology, a fixed thermal conductivity value is usually used when calculating the heat transfer of cables. Although this treatment simplifies the calculation process, it cannot accurately reflect the actual thermal behavior of the cable in a high temperature environment. The simulation results calculated using a fixed and single thermal conductivity coefficient cannot accurately predict the temperature distribution, heat transfer and thermal failure mechanism of the cable in a high temperature environment of a fire, thereby affecting the accuracy and reliability of the simulation results.

[0004] To address the above-mentioned problems, no effective solution has been proposed yet. Summary of the invention

[0005] The embodiment of the present invention provides a method for fitting the thermal conductivity coefficient of a cable material under high temperature fire conditions, so as to at least solve the technical problem that a fixed thermal conductivity coefficient cannot accurately simulate the actual situation of a cable fire.

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

[0007] Step 1: prepare two sets of cable materials, press the outer sheath and the insulating layer of the first set of cable materials into sheets with uniform thickness, and perform differential scanning calorimetry tests on the outer sheath and the insulating layer of the first set of cable materials to determine the respective heat capacities of the outer sheath and the insulating layer of the first set of cable materials at different temperatures;

[0008] Step 2: Press the outer sheath and the insulating layer of the second cable material into a sheet with uniform thickness, evenly arrange a plurality of thermocouples on the outer sheath and the insulating layer of the second cable material, and make an over-temperature test sample of a stacked structure through a high-temperature pressing process;

[0009] Step 3: Build an over-temperature test platform, where the over-temperature test platform includes a simulated fire source device, a cable bracket, 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 multiple thermocouples of the over-temperature test sample when it is over-temperature;

[0011] Step 5: Determine the thermal conductivity of the cable material at different temperatures based on the respective heat capacity values ​​of the outer sheath and the insulation layer of the first cable material obtained in step 1 at different temperatures, and the respective temperature data of multiple thermocouples of the over-temperature test sample when over-temperature obtained in step 4;

[0012] 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 nonlinear fitting is performed on the thermal conductivity of the cable material before, after and during the mutation to obtain a curve of the thermal conductivity of the cable material changing with temperature.

[0013] Optionally, in step 1, two portions of cable materials are prepared, the outer sheath and the insulating layer of the first portion of the cable material are pressed into sheets with uniform thickness, and the outer sheath and the insulating layer of the first portion of the cable material are subjected to differential scanning calorimetry tests to determine the respective heat capacities of the outer sheath and the insulating layer of the first portion of the cable material at different temperatures, comprising the following steps:

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

[0015] Step 1.2: Perform differential scanning calorimetry tests on the outer sheath and insulation layer of the first cable material 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 heat capacity formula: Get the heat capacity of the outer sheath and insulation layer at different temperatures, where C p It 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 insulation layer.

[0016] Optionally, in step 2, the outer sheath and the insulating layer of the second cable material are pressed into a sheet with uniform thickness, and a plurality of thermocouples are evenly arranged on the outer sheath and the insulating layer of the second cable material, and an over-temperature test sample of a stacked structure is manufactured by a high-temperature pressing process, comprising the following steps:

[0017] Step 2.1: pressing the outer sheath and the insulating layer of the second cable material into a sheet with uniform thickness, and evenly arranging a plurality of thermocouples of the same type in an array on the outer sheath and the insulating layer of the second cable material;

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

[0019] Optionally, in step 3, an over-temperature test platform is constructed, wherein the over-temperature test platform comprises a simulated fire source device, a cable bracket, and a high temperature resistant box, and comprises 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 bracket that is suitable for the size of the over-temperature test sample;

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

[0023] Optionally, in step 4, an over-temperature test is performed on the over-temperature test sample, and temperature data of each of a plurality of thermocouples of the over-temperature test sample when the over-temperature test sample is 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 between 30% and 70%, implement remote ignition, and adjust the power of the simulated fire source device to simulate the state of cable material ignition;

[0025] Step 4.2: After remote ignition, turn on the temperature measurement and acquisition system to record the temperature data of multiple thermocouples 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, according to the respective heat capacity values ​​of the outer sheath and the insulating layer of the first cable material at different temperatures obtained in step 1, and the respective temperature data of multiple thermocouples of the over-temperature test sample when over-temperature obtained in step 4, the thermal conductivity of the cable material at different temperatures is determined, comprising the following steps:

[0027] Step 5.1: Calculate the heat flux according to the formula: Q = C p×m×(T-T0) / (t×A), calculate the heat flux density of the outer sheath and insulation layer of the cable material at different temperatures, where Q represents the heat flux density vector flowing through 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 fire-facing surface of the over-temperature test sample 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 thermocouples arranged on the outer sheath and insulation layer of the second cable material;

[0028] Step 5.2: According to Fourier's heat conduction law formula: Every T5, record the thermal conductivity of the outer sheath and insulation layer of the cable material at different temperatures, where Q represents the heat flux density vector flowing through the overtemperature test sample in the thickness direction, L represents the thickness of the outer sheath or insulation layer of the cable material, T1 represents the temperature of the fire-facing side of the overtemperature test sample in the overtemperature test, and T2 represents the temperature of the back-to-fire side of the overtemperature test sample in the overtemperature test. T1 and T2 are measured by thermocouples arranged on the outer sheath and 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 nonlinear fitting is performed on the thermal conductivity of the cable material before, after and during the mutation to obtain a curve graph of the thermal conductivity of the cable material changing with temperature.

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

[0031] The first determination module is used to prepare two portions of cable materials, press the outer sheath and the insulating layer of the first portion of the cable material into sheets with uniform thickness, and perform differential scanning calorimetry tests on the outer sheath and the insulating layer of the first portion of the cable material to determine the respective heat capacities of the outer sheath and the insulating layer of the first portion of the cable material at different temperatures;

[0032] A manufacturing module, used for pressing the outer sheath and the insulating layer of the second cable material into a sheet with uniform thickness, evenly arranging a plurality of thermocouples on the outer sheath and the insulating layer of the second cable material, and manufacturing an over-temperature test sample of a stacked structure through a high-temperature pressing process;

[0033] The test platform building module is used to build an over-temperature test platform, wherein the over-temperature test platform includes a simulated fire source device, a cable bracket, and a high temperature resistant box;

[0034] An over-temperature test module is used to perform an over-temperature test on an over-temperature test sample and record the temperature data of multiple thermocouples of the over-temperature test sample when the sample is over-temperature;

[0035] The second determination module is used to determine the thermal conductivity of the cable material at different temperatures based on the respective 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 respective temperature data of multiple thermocouples of the over-temperature test sample when over-temperature obtained in step 4;

[0036] The fitting module is used to determine the thermal conductivity mutation point of the cable material according to the thermal conductivity of the cable material at different temperatures, and to perform nonlinear fitting on the thermal conductivity of the cable material before, after and during the mutation to obtain a curve graph of the thermal conductivity of the cable material changing with temperature.

[0037] According to another aspect of an embodiment of the present invention, a non-volatile storage medium is provided, which stores a plurality of instructions, wherein the instructions are suitable for being loaded by a processor and executing any one of the methods for fitting the thermal conductivity coefficient of a cable material under high temperature conditions of a fire.

[0038] According to another aspect of an embodiment of the present invention, there is provided an electronic device, comprising: one or more processors and a memory, the memory being used to store 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 for the thermal conductivity coefficient of the cable material under high temperature conditions of a fire.

[0039] According to another aspect of the embodiments of the present invention, there is also provided a computer program product, including a computer program, which, when executed by a processor, implements any of the above-mentioned methods for fitting the thermal conductivity coefficient of a cable material under high temperature conditions of a fire.

[0040] In an embodiment of the present invention, a fitting method for the thermal conductivity of cable materials under high temperature conditions of fire is proposed. The advantages of the present invention are:

[0041] (1) General studies all consider the thermal conductivity of materials in normal operation, and most studies set it as a fixed value. However, cable tunnels are special occasions. To analyze the temperature rise inside multi-layer cables in a high-temperature fire environment, it is necessary to obtain accurate thermal conductivity of different layers of materials. However, the temperature in a fire environment may be much higher than the normal operating temperature, and the material may undergo a phase change. At this time, the thermal conductivity will change significantly, resulting in a large error in the calculation result. The present invention combines experimental test data to perform nonlinear fitting on the thermal conductivity of cable materials before, after, and during the mutation process, and obtains a curve of the thermal conductivity of cable materials changing with temperature. The purpose of simulating cable fires with a thermal conductivity that is more realistic and changes with time is achieved, and the technical problem that a fixed thermal conductivity cannot accurately simulate the actual situation of a cable fire is solved;

[0042] (2) At present, the main methods for measuring the thermal conductivity of materials include the hot wire method, the laser flash method, and the transient plane measurement method, but most of them can only measure the thermal conductivity 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 cumbersome. The present invention first uses a differential scanner with higher universality to measure the heat capacity of cable material samples at different temperatures, and then simulates the internal structure of the cable to press the cable material into a multi-layer structure sample at high temperature for a temperature rise test, and combines the temperature data between each layer obtained by the simulated fire overheating test, and uses the corresponding formula to calculate the thermal conductivity of the cable material sample at different temperatures and fit it, so that the obtained results are more in line with the actual situation. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0044] Figure 1 This is a flow chart of a method for fitting the thermal conductivity of cable materials under high temperature conditions of fire according to an embodiment of the present invention;

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

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

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

[0048] Figure 5is a schematic diagram of a fitting device for the thermal conductivity of a cable material under high temperature conditions of a fire, provided according to an embodiment of the present invention;

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

[0050] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

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

[0052] According to an embodiment of the present invention, an embodiment of a method for fitting the thermal conductivity coefficient of a cable material under high temperature conditions of a fire is provided. 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 a logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0053] Figure 1 FIG. 1 is a flow chart of a method for fitting the thermal conductivity of a cable material under high temperature conditions of a fire according to an embodiment of the present invention. Figure 1 As shown, the method comprises the following steps:

[0054] Step 1: prepare two sets of cable materials, press the outer sheath and the insulating layer of the first set of cable materials into sheets with uniform thickness, and perform differential scanning calorimetry tests on the outer sheath and the insulating layer of the first set of cable materials to determine the respective heat capacities of the outer sheath and the insulating layer of the first set of cable materials at different temperatures;

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

[0056] In an optional embodiment, in step 1, two portions of cable materials are prepared, the outer sheath and the insulating layer of the first portion of the cable material are pressed into sheets with uniform thickness, and the outer sheath and the insulating layer of the first portion of the cable material are subjected to differential scanning calorimetry tests to determine the respective heat capacities of the outer sheath and the insulating layer of the first portion of the cable material at different temperatures, including the following steps:

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

[0058] Step 1.2: Perform differential scanning calorimetry tests on the outer sheath and the insulation layer of the first cable material 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;

[0059] Step 1.3: According to the heat capacity formula: Get the heat capacity of the outer sheath and insulation layer at different temperatures, where C p It 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 insulation layer.

[0060] Optionally, use real cables to make test samples, press the outer sheath and insulation layer materials of the real cables into sheets of uniform thickness, and select the outer sheath and insulation layer of the cable material with a mass of 5 mg for differential scanning calorimetry test. The test is carried out in a nitrogen atmosphere with a gas flow rate of 50 mL / min, and the test temperature is set from 25°C to 180°C with a heating rate of 10°C / min. After the test, draw the heat flow-temperature (DSC) curve, and calculate the heat capacity C of the cable layer material at different temperatures. p , taking the heat capacity of the insulation layer of the cable material at different temperatures as an example, as shown in the following table:

[0061]

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

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

[0064] In an optional embodiment, in step 2, the outer sheath and the insulating layer of the second cable material are pressed into a sheet with uniform thickness, and a plurality of thermocouples are evenly arranged on the outer sheath and the insulating layer of the second cable material, and a stacked structure over-temperature test sample is manufactured by a high-temperature pressing process, comprising the following steps:

[0065] Step 2.1: pressing the outer sheath and the insulating layer of the second cable material into a sheet with uniform thickness, and evenly arranging a plurality of thermocouples of the same type in an array on the outer sheath and the insulating layer of the second cable material;

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

[0067] Optional, such as Figure 2 As shown in the figure, the test sample is made of real cable, and the outer sheath and insulation layer materials of the real cable are pressed into sheets with uniform thickness, and the size can be 25cm×25cm×1cm. Nine K-type thermocouples are arranged in an array on the outer sheath and insulation layer. The thermocouple temperature collection range is -20~500℃, and the thickness is only 0.15mm. The outer sheath and insulation layer are cross-stacked and pressed into a whole by high temperature. Finally, glass fiber insulation boards are installed on both sides of the sample.

[0068] Step 3: Build an over-temperature test platform, where the over-temperature test platform includes a simulated fire source device, a cable bracket, and a high-temperature resistant box;

[0069] In this step, the simulated fire source device includes a combustion plate for placing the over-temperature test sample, a gas supply system consisting of a butane gas cylinder, an adjustable flow valve, a gas supply pipeline, etc., and a remote ignition control device. By adjusting the flow valve to adjust the butane gas flow output from the gas cylinder, the fire source power can be controlled. Considering that the external environment will interfere with the test results, a high-temperature resistant box made of iron of appropriate size is used to cover the platform after the entire test platform is built.

[0070] In an optional embodiment, in step 3, an over-temperature test platform is constructed, wherein the over-temperature test platform includes a simulated fire source device, a cable bracket, and a high temperature resistant box, and includes the following steps:

[0071] 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;

[0072] Step 3.2: Cable support adapted to the size of the over-temperature test specimen;

[0073] Step 3.3: Place the over-temperature test sample on the cable bracket, arrange the simulated fire source device at the center position just below the over-temperature test sample to obtain the over-temperature test platform, and completely cover the over-temperature test platform with a high temperature resistant box.

[0074] Optionally, build an over-temperature test platform, including a simulated fire source device, a cable bracket, a high-temperature resistant box and other test equipment, such as Figure 3 As shown, the over-temperature test sample to be tested is placed on a special cable bracket with a size of 20cm×20cm×60cm. 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. The test platform is covered with a 90cm×90cm×100cm high temperature resistant box to isolate the test platform from the external environment.

[0075] Step 4: Perform an over-temperature test on the over-temperature test sample, and record the temperature data of multiple thermocouples of the over-temperature test sample when it is over-temperature;

[0076] In this step, an over-temperature test is performed on the over-temperature test sample to simulate the actual temperature condition of the cable tunnel when a fire occurs, and the temperature data of each of the multiple thermocouples of the over-temperature test sample when over-temperature occurs are recorded.

[0077] In an optional embodiment, in step 4, an over-temperature test is performed on the over-temperature test sample, and temperature data of each of a plurality of thermocouples of the over-temperature test sample when the over-temperature test sample is 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 between 30% and 70%, implement remote ignition, and adjust the power of the simulated fire source device to simulate the state of cable material ignition;

[0079] Step 4.2: After remote ignition, turn on the temperature measurement and acquisition system to record the temperature data of multiple thermocouples in 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, then turn off the simulated fire source device, and repeat the over-temperature test multiple times. Optionally, the over-temperature test sample to be tested is subjected to a cable material over-temperature test, the initial temperature of the over-temperature test sample is 25°C, and the relative humidity of the environment is about 50%. Implement remote ignition, and turn on the temperature measurement and acquisition system at the same time, record the temperature distribution and changes of each thermocouple between the sample layers during the test, and stop the test when the temperature of the bottom (fire-facing side) of the test sample reaches 250°C, and repeat the test multiple times.

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

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

[0082] In an optional embodiment, in step 5, according to the respective heat capacity values ​​of the outer sheath and the insulating layer of the first cable material at different temperatures obtained in step 1, and the respective temperature data of multiple thermocouples of the over-temperature test sample when over-temperature obtained in step 4, the thermal conductivity of the cable material at different temperatures is determined, comprising the following steps:

[0083] Step 5.1: Calculate the heat flux according to the formula: Q = C p ×m×(T-T0) / (t×A), calculate the heat flux density of the outer sheath and insulation layer of the cable material at different temperatures, where Q represents the heat flux density vector flowing through 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 fire-facing surface of the over-temperature test sample 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 thermocouples arranged on the outer sheath and insulation layer of the second cable material;

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

[0085] Optionally, according to the respective heat capacity values ​​of the outer sheath and the insulation layer of the real cable material at different temperatures obtained in step 1 and the respective temperature data of multiple thermocouples of the over-temperature test sample of the real cable material when over-temperature obtained in step 4, the heat flux density of each layer of the real cable material at different temperatures is calculated by the heat flux density calculation formula, and then according to the Fourier heat conduction law, the thermal conductivity of the cable outer sheath and the insulation layer material at different positions is calculated every 10°C.

[0086] 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 nonlinear fitting is performed on the thermal conductivity of the cable material before, after and during the mutation to obtain a curve 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 is a gradual process within a temperature range. Find the mutation point of thermal conductivity (identify the point where the thermal conductivity decreases or increases, which usually corresponds to the beginning or end of the phase change), and based on this, determine the temperature range of the phase change of the cable material. For example, the phase change temperature range of the cable insulation material is determined to be 120℃-150℃, and the fluid state of the cable insulation appears within this temperature range. The thermal conductivity of the cable material shows different trends before and after the phase change and during the phase change. The thermal conductivity is fitted with a piecewise polynomial nonlinear fitting, and finally a curve of the thermal conductivity of the cable material changing with temperature is obtained. The fitting formulas for the three intervals before, during and after the phase change of cable insulation are:

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

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

[0090] Since the inverse is discontinuous at the breakpoint, the above function is smoothed, such as Figure 4 As shown, the thermal conductivity of the cable insulation material changes with temperature.

[0091] In an embodiment of the present invention, through the above step 1: prepare two portions of cable materials, press the outer sheath and the insulating layer of the first portion of the cable material into a sheet with uniform thickness, and perform differential scanning calorimetry tests on the outer sheath and the insulating layer of the first portion of the cable material, respectively, to determine the respective heat capacities of the outer sheath and the insulating layer of the first portion of the cable material at different temperatures; step 2: press the outer sheath and the insulating layer of the second portion of the cable material into a sheet with uniform thickness, and evenly arrange a plurality of thermocouples on the outer sheath and the insulating layer of the second portion of the cable material, and make an over-temperature test sample of a stacked structure through a high-temperature pressing process; step 3: build an over-temperature test platform, wherein building the over-temperature test platform includes simulating a fire source device, a cable support Rack, high temperature resistant box; Step 4: Conduct over-temperature test on over-temperature test sample, record the temperature data of multiple thermocouples of over-temperature test sample when over-temperature; Step 5: Determine the thermal conductivity of cable material at different temperatures according to the heat capacity values ​​of outer sheath and insulation layer of the first cable material obtained in step 1 at different temperatures, and the temperature data of multiple thermocouples of over-temperature test sample obtained in step 4 when over-temperature; Step 6: Determine the thermal conductivity mutation point of cable material according to the thermal conductivity of cable material at different temperatures, perform nonlinear fitting on the thermal conductivity of cable material before, after and during mutation, and obtain the curve of thermal conductivity of cable material changing with temperature. The purpose of simulating cable fire with thermal conductivity that is more in line with reality and changes with time is achieved, and the technical problem that the real situation of cable fire cannot be accurately simulated with fixed thermal conductivity is solved, thereby achieving the technical effect of improving the accuracy of cable fire simulation.

[0092] Based on the above embodiments and optional embodiments, the present invention proposes an optional implementation mode:

[0093] Step S1: Use real cables to make test samples, press the outer sheath and insulation layer materials of the real cables into sheets with uniform thickness, and select the outer sheath and insulation layer of the cable material with a mass of 5 mg for differential scanning calorimetry test. The test is carried out in a nitrogen atmosphere with a gas flow rate of 50 mL / min, and the test temperature is set from 25°C to 180°C with a heating rate of 10°C / min. After the test, a heat flow-temperature (DSC) curve is drawn, and the heat capacity C of the cable layer material at different temperatures is calculated. p , taking the heat capacity of the insulation layer of the cable material at different temperatures as an example, as shown in the following table:

[0094]

[0095] Step S2: Figure 2 As shown in the figure, the test sample is made of real cable, and the outer sheath and insulation layer materials of the real cable are pressed into sheets with uniform thickness, and the size can be 25cm×25cm×1cm. Nine K-type thermocouples are arranged in an array on the outer sheath and insulation layer. The thermocouple temperature collection range is -20~500℃, and the thickness is only 0.15mm. The outer sheath and insulation layer are cross-stacked and pressed into a whole by high temperature. Finally, glass fiber insulation boards are installed on both sides of the sample.

[0096] Step S3: Build an over-temperature test platform, including a simulated fire source device, a cable bracket, a high temperature resistant box and other test equipment, such as Figure 3 As shown, the over-temperature test sample to be tested is placed on a special cable bracket with a size of 20cm×20cm×60cm. 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. The test platform is covered with a 90cm×90cm×100cm high temperature resistant box to isolate the test platform from the external environment.

[0097] Step S4: Conduct cable material over-temperature test on the over-temperature test sample to be tested, the initial temperature of the over-temperature test sample is 25°C, and the relative humidity of the environment is about 50%. Implement remote ignition, and start the temperature measurement and acquisition system at the same time, record the temperature distribution and changes of each thermocouple between the sample layers during the test, and stop the test when the temperature of the bottom (fire-facing surface) of the test sample reaches 250°C, and repeat the test multiple times.

[0098] Step S5: According to the respective heat capacity values ​​of the outer sheath and the insulating layer of the real cable material at different temperatures obtained in step S1 and the respective temperature data of multiple thermocouples of the over-temperature test sample of the real cable material when over-temperature obtained in step S4, the heat flux density calculation formula is used to calculate the heat flux density of each layer of the real cable material at different temperatures, and then according to the Fourier heat conduction law, the thermal conductivity of the cable outer sheath and the insulating layer material at different positions is calculated every 10°C.

[0099] Step S6: Consider that the phase change does not occur instantaneously, but is a gradual process within a temperature range. 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 based on this, determine the temperature range of the cable material phase change. For example, the phase change temperature range of the cable insulation material is determined to be 120℃-150℃, and the fluid state of the cable insulation appears within this temperature range. The thermal conductivity of the cable material shows different trends before and after the phase change and during the phase change. The thermal conductivity is fitted with a piecewise polynomial nonlinear fitting, and finally a curve of the thermal conductivity of the cable material changing with temperature is obtained. The fitting formulas for the three intervals before, during and after the phase change of cable insulation are:

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

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

[0102] y3=-3.2571410 -6 x 3 +0.00156x 2 -0.24803x+13.49946, 145℃≤x≤180℃.

[0103] Since the inverse is discontinuous at the breakpoint, the above function is smoothed to obtain the thermal conductivity of the cable insulation material as a function of temperature: Figure 4 shown.

[0104] The above optional implementation achieves at least the following effects: the purpose of simulating cable fires with a thermal conductivity that is more realistic and changes with time is achieved, the technical problem that a fixed thermal conductivity cannot accurately simulate the actual situation of a cable fire 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 flowcharts of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and that, although a logical order is shown in the flowcharts, in some cases, the steps shown or described can be executed in an order different from that shown here.

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

[0107] The first determination module 51 is used to prepare two sets of cable materials, press the outer sheath and the insulation layer of the first set of cable materials into sheets with uniform thickness, and perform differential scanning calorimetry tests on the outer sheath and the insulation layer of the first set of cable materials to determine the heat capacity values ​​of the outer sheath and the insulation layer of the first set of cable materials at different temperatures;

[0108] The manufacturing module 52 is connected to the first determining module 51, and is used to press the outer sheath and the insulating layer of the second cable material into a sheet with uniform thickness, and evenly arrange a plurality of thermocouples on the outer sheath and the insulating layer of the second cable material, and manufacture them into an over-temperature test sample with a stacked structure through a high-temperature pressing process;

[0109] The test platform building module 53 is connected to the manufacturing module 52 and is used to build an over-temperature test platform, wherein the over-temperature test platform includes a simulated fire source device, a cable bracket, and a high temperature resistant box;

[0110] An over-temperature test module 54 is connected to the test platform building module 53 and is used to perform an over-temperature test on the over-temperature test sample and record the temperature data of each of the multiple thermocouples when the over-temperature test sample is over-heated;

[0111] The second determination module 55 is connected to the over-temperature test module 54 and is used to determine the thermal conductivity of the cable material at different temperatures based on the respective 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 respective temperature data of the multiple thermocouples of the over-temperature test sample when over-temperature obtained in step 4;

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

[0113] In a fitting method for the thermal conductivity coefficient of a cable material under high temperature conditions of a fire provided by an embodiment of the present invention, a first determination module is set up to prepare two portions of cable materials, and the outer sheath and the insulating layer of the first portion of the cable material are pressed into sheets with uniform thickness, and the outer sheath and the insulating layer of the first portion of the cable material are subjected to differential scanning calorimetry tests respectively to determine the respective heat capacity values ​​of the outer sheath and the insulating layer of the first cable material at different temperatures; a production module is used to press the outer sheath and the insulating layer of the second portion of the cable material into sheets with uniform thickness, and a plurality of thermocouples are evenly arranged on the outer sheath and the insulating layer of the second portion of the cable material, and are produced into an over-temperature test sample with a stacked structure through a high-temperature pressing process; and a test platform construction module is used to build an over-temperature test platform, wherein the over-temperature test is built The platform includes a simulated fire source device, a cable bracket, and a high temperature resistant box; an over-temperature test module, which is used to perform an over-temperature test on the over-temperature test sample and record the temperature data of multiple thermocouples of the over-temperature test sample when it is over-temperature; a second determination module, which is used to determine the thermal conductivity of the cable material at different temperatures according to the respective heat capacity values ​​of the outer sheath and the insulation layer of the first cable material obtained in step 1 at different temperatures, and the respective temperature data of multiple thermocouples of the over-temperature test sample obtained in step 4 when it is over-temperature; a fitting module, which is used to 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, after and during the mutation, respectively, to obtain a curve of the thermal conductivity of the cable material changing with temperature. The purpose of simulating cable fires with a thermal conductivity that is more realistic and changes with time is achieved, and the technical problem that the real situation of cable fires cannot be accurately simulated with a fixed thermal conductivity is solved, thereby achieving the technical effect of improving the accuracy of cable fire simulation.

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

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

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

[0117] The above-mentioned cable fire simulation device may also include a processor and a memory, including a first determination module 51, a production module 52, a test platform construction module 53, an overtemperature test module 54, a second determination module 55, a fitting module 56, etc., which are all stored in the memory as program units, and the processor executes the above-mentioned program units stored in the memory to realize corresponding functions.

[0118] The processor includes a kernel, which retrieves the corresponding program unit from the memory. There can be one or more kernels. The memory may include non-permanent memory in a computer-readable medium, random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM, and the memory includes at least one storage chip.

[0119] An embodiment of the present invention provides a non-volatile storage medium on which a program is stored. When the program is executed by a processor, a method for fitting the thermal conductivity coefficient of a cable material under high temperature conditions of a fire is implemented.

[0120] like Figure 6 It is shown that an embodiment of the present invention provides an electronic device, 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 implemented: the memory is used to store a computer program, wherein, when the computer program is executed by the processor, the processor implements the above-mentioned method for fitting the thermal conductivity coefficient of the cable material under high temperature conditions of a fire. The device in this article can be a server, a PC, etc.

[0121] The present invention also provides a computer program product, which, when executed on a data processing device, is suitable for executing a program that initializes the following method steps: computer instructions are executed by a processor to perform the above-mentioned method for fitting the thermal conductivity coefficient of a cable material under high temperature conditions of a fire.

[0122] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may 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-ROM, optical storage, etc.) containing computer-usable program code.

[0123] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0124] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0125] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process in the computer or other programmable device. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

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

[0127] The memory may include non-permanent memory in a computer-readable medium, random access memory (RAM) and / or non-volatile memory in the form of read-only memory (ROM) or flash RAM. The memory is an example of a computer-readable medium.

[0128] Computer readable media include permanent and non-permanent, removable and non-removable media that can be implemented by any method or technology to store information. 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 technology, compact disk read-only memory (CD-ROM), digital versatile disk (DVD) or other optical storage, magnetic cassettes, magnetic tape disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer readable media does not include temporary computer readable media (transitory media), such as modulated data signals and carrier waves.

[0129] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0130] It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as methods, systems or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment or an embodiment combining software and hardware. Moreover, the present invention may 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-ROM, optical storage, etc.) containing computer-usable program codes.

[0131] The above are only embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A method for fitting the thermal conductivity of cable materials under high temperature conditions of fire, characterized in that: The following steps are involved: Step 1: preparing two portions of cable materials, pressing the outer sheath and the insulating layer of the first portion of the cable material into sheets with uniform thickness, and performing differential scanning calorimetry tests on the outer sheath and the insulating layer of the first portion of the cable material to determine the respective heat capacities of the outer sheath and the insulating layer of the first portion of the cable material at different temperatures; Step 2: Press the outer sheath and the insulating layer of the second cable material into a sheet with uniform thickness, evenly arrange a plurality of thermocouples on the outer sheath and the insulating layer of the second cable material, and make an over-temperature test sample of a stacked structure through 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 bracket, 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 multiple thermocouples when the over-temperature test sample is over-temperature; Step 5: Determine the thermal conductivity of the cable material at different temperatures based on the respective heat capacity values ​​of the outer sheath and the insulating layer of the first cable material obtained in step 1 at different temperatures, and the respective temperature data of the multiple thermocouples of the over-temperature test sample when over-temperature obtained in step 4; 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 nonlinear fitting is performed on the thermal conductivity of the cable material before, after and during the mutation to obtain a curve graph of the thermal conductivity of the cable material changing with temperature.

2. The method according to claim 1, characterized in that In the step 1, two portions of cable materials are prepared, the outer sheath and the insulating layer of the first portion of the cable material are pressed into sheets with uniform thickness, and the outer sheath and the insulating layer of the first portion of the cable material are subjected to differential scanning calorimetry tests to determine the respective heat capacities of the outer sheath and the insulating layer of the first portion of the cable material at different temperatures, including the following steps: Step 1.1: prepare two portions of cable materials, and press the outer sheath and the insulating layer of the first portion of the cable material into a sheet with uniform thickness; Step 1.2: performing the differential scanning calorimetry test on the outer sheath and the insulating 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 heat capacity formula: The heat capacity values ​​of the outer protective layer and the insulating layer at different temperatures are obtained, wherein the C p represents the heat capacity value, the ΔH represents the heat flow per unit time on the heat flow-temperature curve, and the m represents the mass of the outer protective layer or the insulating layer.

3. The method according to claim 1, characterized in that In the step 2, the outer sheath and the insulating layer of the second cable material are pressed into a sheet with uniform thickness, and a plurality of thermocouples are evenly arranged on the outer sheath and the insulating layer of the second cable material, and an over-temperature test sample of a stacked structure is manufactured by a high-temperature pressing process, comprising the following steps: Step 2.1: pressing the outer sheath and the insulating layer of the second portion of the cable material into a sheet with uniform thickness, and evenly arranging a plurality of thermocouples of the same type in an array on the outer sheath and the insulating layer of the second portion of the cable material; Step 2.2: The outer sheath and the insulating layer of the second cable material on which a plurality of thermocouples of the same type are arranged are pressed into one piece by the high-temperature pressing process to obtain an over-temperature test sample.

4. The method according to claim 1, characterized in that: In step 3, an over-temperature test platform is constructed, wherein the over-temperature test platform comprises a simulated fire source device, a cable bracket, and a high temperature resistant box, and comprises the following steps: Step 3.1: constructing the 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; Step 3.2: Build a cable bracket that is suitable for the size of the over-temperature test sample; Step 3.3: Place the over-temperature test sample on the cable bracket, arrange the simulated fire source device at the center position directly below the over-temperature test sample to obtain the over-temperature test platform, and completely cover the over-temperature test platform with the high temperature resistant box.

5. The method according to claim 1, characterized in that In step 4, an over-temperature test is performed on the over-temperature test sample, and temperature data of each of the multiple thermocouples of the over-temperature test sample when the over-temperature test sample is over-temperature is recorded, including the following steps: Step 4.1: setting the initial temperature of the test sample to T3, the relative humidity of the environment to between 30% and 70%, implementing remote ignition, and adjusting the power of the simulated fire source device to simulate the state of the cable material catching fire; Step 4.2: After remote ignition, turn on the temperature measurement and acquisition system to record the temperature data of multiple thermocouples of each layer of the overtemperature test sample during the overtemperature test, until the temperature at the bottom of the overtemperature test sample reaches T4, turn off the simulated fire source device, and repeat the overtemperature test multiple times.

6. The method according to claim 1, characterized in that In the step 5, according to the respective heat capacity values ​​of the outer sheath and the insulating layer of the first cable material at different temperatures obtained in the step 1, and the respective temperature data of the multiple thermocouples of the over-temperature test sample when over-temperature obtained in the step 4, the thermal conductivity of the cable material at different temperatures is determined, comprising the following steps: Step 5.1: Calculate the heat flux according to the formula: Q = C p ×m×(T-T0) / (t×A), calculate the heat flux density of the outer sheath and insulation layer of the cable material at different temperatures, where Q represents the heat flux density vector flowing through the thickness direction of the sample, and C p represents the heat capacity value, m represents the mass of the outer sheath or the insulating layer, T represents the temperature of the fire-facing surface of the over-temperature test sample 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 thermocouples arranged on the outer sheath and the insulating layer of the second cable material; Step 5.2: According to Fourier's 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 over-temperature test sample in the thickness direction, L represents the thickness of the outer sheath or insulation layer of the cable material, T1 represents the temperature of the fire-facing side of the over-temperature test sample in the over-temperature test, and T2 represents the temperature of the back-fire side of the over-temperature test sample in the over-temperature test, and T1 and T2 are measured by thermocouples arranged on the outer sheath and insulation layer of the second cable material.

7. A fitting device for the thermal conductivity of cable materials under high temperature conditions of fire, characterized in that: include: A first determination module is used to prepare two portions of cable materials, press the outer sheath and the insulating layer of the first portion of the cable material into sheets with uniform thickness, and perform differential scanning calorimetry tests on the outer sheath and the insulating layer of the first portion of the cable material to determine the respective heat capacities of the outer sheath and the insulating layer of the first portion of the cable material at different temperatures; A manufacturing module, used for pressing the outer sheath and the insulating layer of the second cable material into a sheet with uniform thickness, evenly arranging a plurality of thermocouples on the outer sheath and the insulating layer of the second cable material, and manufacturing an over-temperature test sample of a stacked structure through a high-temperature pressing process; A test platform construction module, used to construct an over-temperature test platform, wherein the over-temperature test platform comprises a simulated fire source device, a cable bracket, and a high temperature resistant box; An over-temperature test module, used to perform an over-temperature test on the over-temperature test sample and record the temperature data of each of the multiple thermocouples when the over-temperature test sample is over-temperature; A second determination module is used to determine the thermal conductivity of the cable material at different temperatures based on the respective 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 respective temperature data of the multiple thermocouples of the over-temperature test sample when over-temperature obtained in step 4; The fitting module is used to determine the thermal conductivity mutation point of the cable material according to the thermal conductivity of the cable material at different temperatures, and to perform nonlinear fitting on the thermal conductivity of the cable material before, after and during the mutation to obtain a curve graph of the thermal conductivity of the cable material changing with temperature.

8. A non-volatile storage medium, characterized in that: The non-volatile storage medium stores a plurality of instructions, and the instructions are suitable for being loaded by a processor and executed by a method for fitting the thermal conductivity coefficient of a cable material under high temperature fire conditions as described in any one of claims 1 to 6.

9. An electronic device, characterized in that: include: One or more processors and a memory, the memory being used to store 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 a method for fitting the thermal conductivity coefficient of a cable material under high temperature fire conditions as described in 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 a method for fitting the thermal conductivity coefficient of a cable material under high temperature fire conditions as described in any one of claims 1 to 6.

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