System and method for evaluating combustibility of a solid material

Abstract

The present application relates to the technical field of flammability evaluation, in particular to a system and method for evaluating flammability of solid materials. The system can monitor the bottom surface temperature of the solid material by setting a temperature measuring device, and can monitor the top surface thickness of the solid material by setting a camera. Then, the bottom surface temperature and the top surface thickness are numerically inverted to obtain the thermal physical parameters of the solid material. The thermal physical parameters are taken as input samples, and the mass loss measured by the balance is taken as output samples. The heat and mass transport model is constructed by using the input samples and the output samples, so as to predict the mass loss of the sample to be tested by using the heat and mass transport model. The gas analyzer is set to monitor the concentrations of oxygen, hydrogen, carbon dioxide, carbon monoxide and hydrocarbons, so as to obtain the heat release rate of the solid material in the pyrolysis combustion process by using the oxygen consumption principle. Therefore, the above technical scheme can accurately determine the flammability evaluation index of the solid material.

Description

Technical Field

[0001] This invention relates to the field of flammability evaluation technology, and in particular to a flammability evaluation system and method for solid materials. Background Technology

[0002] A solid material heating experimental device (or pyrolysis combustion device) is a device for studying the thermophysical parameters of solid materials, including thermal conductivity, density, depth absorption coefficient, and radiation coefficient. These parameters affect the flammability evaluation indicators of solid materials, such as pyrolysis mass loss and heat release rate.

[0003] However, the relevant technologies have difficulty accurately determining the flammability evaluation indicators of solid materials. Summary of the Invention

[0004] This invention provides a system and method for evaluating the flammability of solid materials, which can accurately determine the flammability evaluation indicators of solid materials.

[0005] In a first aspect, embodiments of the present invention provide a flammability evaluation system for solid materials, comprising a sealed pyrolysis chamber, a radiation heater formed above the pyrolysis chamber, a sample tray located directly below the radiation heater, a first cooling chamber formed on the side of the pyrolysis chamber, a second cooling chamber located on the outer periphery of the sample tray, and a heat exchange medium located between the first cooling chamber and the second cooling chamber. An exhaust port is provided directly above the pyrolysis chamber, allowing pyrolysis gas to enter the pyrolysis chamber from below the heat exchange medium. The heat exchange medium is used to absorb the heat from the pyrolysis gas. A gas analyzer is provided at the exhaust port to monitor the concentrations of oxygen, hydrogen, carbon dioxide, carbon monoxide, and hydrocarbons. The sample tray is used to hold cylindrical solid materials, and a balance is provided below the sample tray. Both the first and second cooling chambers are used to introduce cooling media.

[0006] It also includes a temperature measuring device for measuring the temperature of the bottom surface of the solid material and a camera for measuring the thickness of the top surface of the solid material.

[0007] Secondly, embodiments of the present invention provide a method for evaluating the flammability of solid materials, applied to the system described in the above embodiments, comprising:

[0008] The temperature of the bottom surface of the solid material is monitored using the temperature measuring device.

[0009] The camera is used to monitor the thickness of the top surface of the solid material;

[0010] The thermal properties of the solid material are obtained by numerically inverting the bottom surface temperature and the top surface thickness.

[0011] The thermophysical parameters are used as input samples and the mass loss measured by the balance is used as output samples. A thermo-mass transport model is constructed using the input samples and the output samples, so as to predict the mass loss of the sample to be tested.

[0012] The concentrations of oxygen, hydrogen, carbon dioxide, carbon monoxide, and hydrocarbons are monitored using the gas analyzer, so as to obtain the heat release rate of the solid material during the pyrolysis combustion process using the principle of oxygen consumption.

[0013] As can be seen from the above scheme, the flammability evaluation system and method for solid materials provided by the present invention can monitor the bottom surface temperature of the solid material by setting a temperature measuring device; monitor the top surface thickness of the solid material by setting a camera; then perform numerical inversion on the bottom surface temperature and top surface thickness to obtain the thermophysical parameters of the solid material; thus, using the thermophysical parameters as input samples and the mass loss measured by the balance as output samples, a thermo-mass transport model is constructed using the input and output samples to predict the mass loss of the sample under test; by setting a gas analyzer, the concentrations of oxygen, hydrogen, carbon dioxide, carbon monoxide, and hydrocarbons can be monitored to obtain the heat release rate of the solid material during pyrolysis combustion using the oxygen consumption principle. Therefore, the above technical solution can accurately determine the flammability evaluation index of solid materials. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a cross-sectional schematic diagram of the solid material flammability evaluation system provided in an embodiment of the present invention.

[0016] Figure label:

[0017] 1-Pyrolysis chamber;

[0018] 11 - Exhaust port;

[0019] 2-Radiation heater;

[0020] 3-Sample tray;

[0021] 31-Balance scale;

[0022] 32-High reflectivity mirror;

[0023] 4-First cooling chamber;

[0024] 41 - Visual window;

[0025] 5-Second cooling chamber;

[0026] 6-Heat exchange medium;

[0027] 7-Temperature measuring device;

[0028] 8-Camera. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Please see Figure 1 An embodiment of the present invention provides a flammability evaluation system for solid materials. The system includes a sealed pyrolysis chamber 1, a radiation heater 2 formed above the pyrolysis chamber 1, a sample plate 3 located directly below the radiation heater 2, a first cooling chamber 4 formed on the side of the pyrolysis chamber 1, a second cooling chamber 5 located on the outer periphery of the sample plate 3, and a heat exchange medium 6 located between the first cooling chamber 4 and the second cooling chamber 5. An exhaust port 11 is provided directly above the pyrolysis chamber 1, through which pyrolysis gas can enter the pyrolysis chamber 1 from below the heat exchange medium 6. The heat exchange medium 6 is used to absorb the heat of the pyrolysis gas. A gas analyzer (not shown in the figure) is provided at the exhaust port 11 to monitor the concentration of oxygen, hydrogen, carbon dioxide, carbon monoxide, and hydrocarbons. The sample plate 3 is used to hold cylindrical solid materials. A balance 31 is provided below the sample plate 3. Both the first cooling chamber 4 and the second cooling chamber 5 are used to introduce cooling media.

[0031] It also includes a temperature measuring device 7 for measuring the temperature of the bottom surface of the solid material and a camera 8 for measuring the thickness of the top surface of the solid material.

[0032] In this embodiment, a temperature measuring device 7 can be used to monitor the bottom surface temperature of the solid material; a camera 8 can be used to monitor the top surface thickness of the solid material; then, numerical inversion is performed on the bottom surface temperature and top surface thickness to obtain the thermophysical parameters of the solid material; using these thermophysical parameters as input samples and the mass loss measured by the balance 31 as output samples, a thermo-mass transport model is constructed using the input and output samples to predict the mass loss of the sample under test; a gas analyzer can be used to monitor the concentrations of oxygen, hydrogen, carbon dioxide, carbon monoxide, and hydrocarbons to obtain the heat release rate of the solid material during pyrolysis combustion using the oxygen consumption principle. Therefore, the above technical solution can accurately determine the flammability evaluation index of solid materials.

[0033] Specifically, based on the premise that the pyrolysis chamber 1 is a closed chamber, the atmosphere of the pyrolysis gas input into the pyrolysis chamber 1 is controlled, and the concentrations of oxygen, hydrogen, carbon dioxide, carbon monoxide and hydrocarbons are monitored by a gas analyzer. In this way, the gas composition can be accurately monitored, and the heat release rate of the solid material during the pyrolysis combustion process can be obtained based on the oxygen consumption principle.

[0034] Specifically, when constructing a heat and mass transport model, it is necessary to ensure the accuracy of the numerical simulation results of the thermal boundary. Therefore, by introducing cooling medium into the first cooling chamber 4 and the second cooling chamber 5 and using heat exchange medium 6 to absorb the heat of the pyrolysis gas, it is possible to ensure that the pyrolysis chamber 1 has uniform thermal boundary conditions, thereby improving the repeatability of experimental results and ensuring the accuracy of the numerical simulation results of the thermal boundary.

[0035] It should be noted that the sample undergoes a pyrolysis reaction under radiant heating conditions, accompanied by reaction and heat and mass transfer processes within the sample. The composition and concentration of the gas atmosphere in the pyrolysis chamber 1 can be adjusted, and the chamber's airtightness helps in the accurate determination of the pyrolysis gas composition / concentration at the downstream end.

[0036] It is worth noting that, compared with using copper tubes embedded in the pyrolysis chamber 1 for partial cooling, this system can achieve full-circumferential cooling of the pyrolysis chamber 1 by setting up the first cooling chamber 4 and the second cooling chamber 5. This can ensure uniform thermal boundary conditions during the sample heating process, thereby helping to improve the repeatability of experimental results, providing accurate thermal boundary conditions for the numerical inversion process, and ensuring the accuracy of the numerical inversion results.

[0037] In one embodiment of the present invention, the radiation heater 2 has a frustum-shaped structure, with the exhaust port 11 located on the top surface of the frustum-shaped structure and the sample disk 3 located below the bottom surface of the frustum-shaped structure. The diameter of the bottom surface of the frustum-shaped structure is larger than the diameter of the top surface. This arrangement ensures the uniformity of radiative heating of the sample.

[0038] In one embodiment of the present invention, a copper foil is placed on the bottom surface of the sample tray 3, and black paint with a known emissivity (e.g., 0.95) (capable of withstanding high temperatures of 700°C) is applied to the copper foil. A high-reflectivity mirror 32, tilted at 45°, is placed directly below the copper foil. The temperature measuring device 7 is an infrared thermal imager, positioned in the direction of light emission from the high-reflectivity mirror 32. This arrangement enables non-contact, real-time measurement of the sample bottom surface temperature. Compared to direct temperature measurement using thermocouples, the former can obtain more uniform data characterizing the sample temperature, while thermocouples can only measure the position of a single point in the sample, resulting in less accurate and objective results.

[0039] In some implementations, the high-precision balance 31 can accurately measure the mass change of the sample during pyrolysis and vaporization (e.g., with an accuracy of 0.001 g).

[0040] In one embodiment of the present invention, the cooling medium is cooling water.

[0041] In one embodiment of the present invention, the heat exchange medium 6 is ceramic beads. This arrangement facilitates the uniform entry of pyrolysis gas into the pyrolysis chamber 1 after passing through the gaps in the ceramic beads.

[0042] In one embodiment of the present invention, the system further includes a slide rail (not shown in the figure), which is connected to the radiant heater 2. The radiant heater 2 can move upward, downward, leftward, and rightward on the slide rail. This configuration ensures complete collection of the sample to generate expanding carbon residue upon heating. The carbon residue can be CT scanned to obtain its complete three-dimensional structure, which is crucial for accurately analyzing its heat and mass transfer processes.

[0043] In one embodiment of the present invention, the camera 8 is located outside the pyrolysis chamber 1, and the first cooling chamber 4 has a viewing window 41. The camera 8 can capture the top surface height of the solid material through the viewing window 41. With this configuration, the camera 8 can record the real-time changes in the morphology (i.e., thickness or top surface height) of the sample during the pyrolysis process.

[0044] In one embodiment of the present invention, the system further includes simulation software (not shown in the figure, such as ThermaKin2Ds). The simulation software is used to perform numerical inversion on the bottom surface temperature measured by the temperature measuring device 7 and the top surface thickness measured by the camera 8 to obtain the thermal property parameters of the solid material. The thermal property parameters are used as input samples, and the mass loss measured by the balance 31 is used as an output sample. The input and output samples are used to construct a thermo-mass transport model, which is used to predict the mass loss of the sample to be tested. The sample to be tested and the solid material belong to the same type of material. With this setup, the thermal property parameters of a solid material of the same type as the sample can be obtained from a single sample, thereby enabling faster flammability evaluation of other samples of the same type.

[0045] In one embodiment of the present invention, the thermal properties include thermal conductivity, density, depth absorption coefficient, and emissivity.

[0046] In summary, the above technical solutions can improve the accuracy and repeatability of experimental results, while ensuring that the constructed numerical model can accurately predict the pyrolysis process of the sample.

[0047] Furthermore, embodiments of the present invention also provide a method for evaluating the flammability of solid materials, applied to the system mentioned in any of the above embodiments, comprising:

[0048] The temperature of the bottom surface of the solid material is monitored using temperature measuring device 7;

[0049] Camera 8 is used to monitor the thickness of the top surface of the solid material;

[0050] Numerical inversion of bottom surface temperature and top surface thickness yields the thermal properties of the solid material.

[0051] Thermophysical parameters are used as input samples and mass loss measured by balance 31 is used as output samples. A thermo-mass transport model is constructed using the input and output samples to predict the mass loss of the sample under test.

[0052] The concentrations of oxygen, hydrogen, carbon dioxide, carbon monoxide, and hydrocarbons are monitored using a gas analyzer, so as to obtain the heat release rate of solid materials during pyrolysis combustion by utilizing the principle of oxygen consumption.

[0053] It is understood that the method embodiments and system embodiments provided by the present invention are based on the same inventive concept and have the same beneficial effects. The beneficial effects of the method embodiments will not be elaborated here.

[0054] It should be noted that, in this invention, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus.

[0055] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and is only used to illustrate the technical solution of the present invention, and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of protection of the present invention.

Claims

1. A method for evaluating the flammability of solid materials, characterized in that, A system for evaluating the flammability of solid materials includes a sealed pyrolysis chamber (1), a radiation heater (2) formed above the pyrolysis chamber (1), a sample plate (3) located directly below the radiation heater (2), a first cooling chamber (4) formed on the side of the pyrolysis chamber (1), a second cooling chamber (5) located on the outer periphery of the sample plate (3), and a heat exchange medium (6) located between the first cooling chamber (4) and the second cooling chamber (5). An exhaust port (11) is provided directly above the pyrolysis chamber (1), through which pyrolysis gas can enter the pyrolysis chamber (1) from below the heat exchange medium (6). A gas analyzer is provided at the exhaust port (11) for monitoring the concentrations of oxygen, hydrogen, carbon dioxide, carbon monoxide, and hydrocarbons. The sample plate (3) is used to hold cylindrical solid materials. A balance (31) is provided below the sample plate (3). It also includes a temperature measuring device (7) for measuring the temperature of the bottom surface of the solid material and a camera (8) for measuring the thickness of the top surface of the solid material; The method includes: The temperature of the bottom surface of the solid material is monitored using the temperature measuring device (7); The thickness of the top surface of the solid material is monitored using the camera (8); The thermal properties of the solid material are obtained by numerical inversion of the bottom surface temperature and the top surface thickness. The pyrolysis chamber (1) is cooled around by introducing cooling medium into the first cooling chamber (4) and the second cooling chamber (5) and by absorbing the heat of the pyrolysis gas using the heat exchange medium (6). This ensures that the pyrolysis chamber (1) has uniform thermal boundary conditions, thereby improving the repeatability of experimental results and ensuring the accuracy of numerical simulation results of thermal boundary conditions. The cooling medium is cooling water, and the heat exchange medium (6) is ceramic beads, so that the pyrolysis gas can enter the pyrolysis chamber (1) uniformly after passing through the gaps in the ceramic beads. The thermophysical parameters are used as input samples and the mass loss measured by the balance (31) is used as output samples. A thermo-mass transport model is constructed using the input samples and the output samples, so as to predict the mass loss of the sample to be tested using the thermo-mass transport model. The concentrations of oxygen, hydrogen, carbon dioxide, carbon monoxide and hydrocarbons are monitored using the gas analyzer to obtain the heat release rate of the solid material during the pyrolysis combustion process using the oxygen consumption principle; wherein, the solid material undergoes pyrolysis reaction under radiation heating conditions, and the solid material is accompanied by reaction and heat and mass transfer processes; the composition and concentration of the gas atmosphere in the pyrolysis chamber (1) can be adjusted, and the chamber sealing helps to accurately determine the composition / concentration of the pyrolysis gas at the downstream end.

2. The method according to claim 1, characterized in that, The radiation heater (2) has a frustum-shaped structure. The exhaust port (11) is located on the top surface of the frustum-shaped structure. The sample plate (3) is located below the bottom surface of the frustum-shaped structure. The diameter of the bottom surface of the frustum-shaped structure is larger than the diameter of the top surface.

3. The method according to claim 2, characterized in that, The bottom surface of the sample tray (3) is provided with copper foil paper, which is coated with black paint with a known emissivity. A high reflective mirror (32) is placed at a 45° angle directly below the copper foil paper. The temperature measuring device (7) is an infrared thermal imager, which is positioned in the light emission direction of the high reflective mirror (32).

4. The method according to claim 3, characterized in that, It also includes a slide rail connected to the radiant heater (2), which is capable of moving up, down, left and right on the slide rail.

5. The method according to claim 4, characterized in that, The camera (8) is located outside the pyrolysis chamber (1), and the first cooling chamber (4) has a viewing window (41). The camera (8) can capture the top surface height of the solid material through the viewing window (41).

6. The method according to claim 5, characterized in that, It also includes simulation software, which is used to perform numerical inversion on the bottom surface temperature measured by the temperature measuring device (7) and the top surface thickness measured by the camera (8) to obtain the thermal property parameters of the solid material; wherein, the thermal property parameters are used as input samples, the mass loss measured by the balance (31) is used as output samples, the input samples and the output samples are used to construct a thermo-mass transport model, the thermo-mass transport model is used to predict the mass loss of the sample to be tested, and the sample to be tested and the solid material are of the same type of material.

7. The method according to claim 6, characterized in that, The thermophysical parameters include thermal conductivity, density, depth absorption coefficient, and emissivity.

Images