Multi-surface radiation accelerated pyrolysis combustion experiment device and test method

Abstract

The invention discloses a multi-surface radiation accelerated pyrolysis combustion experiment device and a test method, and belongs to the technical field of combustible combustion, the device comprises a heating unit, a control unit and a measuring unit; the heating unit comprises a plurality of heating cones and a sample piece box; a sample piece is embedded into the sample piece box, and only a plurality of surfaces are exposed as test heating surfaces; the plurality of heating cones are in one-to-one correspondence with a plurality of test heating surfaces of the sample piece and heat the test heating surfaces; the control unit is used for controlling the heating cone to heat; the measuring unit is used for measuring the surface temperature of the sample piece, the quality of the sample piece and the heat flow of the heating cone and monitoring the state of the sample piece. The device is simple and easy to operate, has high reliability, can realize ignition experiments of two-side heating of edges at different angles and three-side heating of vertexes at different angles, and has high repeatability and accuracy of test results.

Description

Technical Field

[0001] The invention belongs to the technical field of combustible combustion, and relates to a combustion experimental device for solid angular combustibles, and in particular to a multi-faceted radiation accelerated pyrolysis combustion experimental device and a testing method. Background Art

[0002] Solid pyrolysis ignition is the precursor process of fire, and the spread of fire after ignition is essentially the continuous ignition of unburned areas caused by flame heat feedback. Traditional solid flammability test standards (International ISO 5660, China GB / T 16172, US ASTME1354, EU EN 13823, UK BS 476, Japan JIS A 1301, etc.) and standard test instruments (cone calorimeter, flame propagation instrument (FPA), etc.) mostly focus on flat materials (such as wood boards, etc.). Such test methods and instruments are relatively simple and are not suitable for accelerated disaster scenarios in the thermal environment of fires in thermally fragile parts of solid edges.

[0003] Solid corner pyrolysis ignition and fire spread acceleration effect are common in building fires, mostly on building facades and indoor furniture corners. Recent experimental studies have shown that the minimum critical heat flux for solid plane ignition is 15~20 kW / m 2 , while the minimum critical heat flux for ignition of right-angled edges is 5~12 kW / m 2 , that is, the edges and corners are more likely to reach the pyrolysis temperature and catch fire due to multi-faceted heating. After ignition, the fire spreads faster and the fire hazard is higher. However, the existing experimental device has limitations and can only measure the pyrolysis and ignition process of the solid combustible surface under the action of single-sided radiation heat flux, resulting in significant differences between the experimental scene and the actual fire scene. Summary of the invention

[0004] The invention provides a multi-surface radiation accelerated pyrolysis and combustion experimental device and a testing method to overcome the defects of the prior art.

[0005] To achieve the above object, the present invention adopts the following technical solutions: A multi-faceted radiation accelerated pyrolysis and combustion experimental device comprises a heating unit, a control unit and a measuring unit; the heating unit comprises a plurality of heating cones and a sample box; the sample is embedded in the sample box, with only a plurality of faces exposed as test heating faces; the plurality of heating cones correspond to the plurality of test heating faces of the sample one by one, and heat the faces; the control unit is used for controlling the heating of the heating cones; the measuring unit is used for measuring the surface temperature of the sample, the mass of the sample and the heat flow of the heating cones, and monitoring the state of the sample (whether it is on fire).

[0006] To optimize the above technical solutions, the specific measures taken also include: Furthermore, the heating unit also includes a heat-insulating baffle; the heat-insulating baffle is used to be placed between the test heating surface and the heating cone before the experiment to isolate the radiation of the heating cone.

[0007] Furthermore, the materials of the heat insulation baffle and the sample box are both high temperature resistant ceramic fibers.

[0008] Furthermore, the number of the heating cones is two; the sample is embedded in the sample box, exposing two adjacent surfaces with the same edge as the test heating surface; the two heating cones are placed in combination, facing the two test heating surfaces one by one, forming a double-sided structure with the same edge angle as the two test heating surfaces; the thermal insulation baffle is formed by splicing two thermal insulation panels to form a double-sided structure with the same edge angle as the two test heating surfaces, and is placed between the corresponding test heating surface and the heating cone before the experiment.

[0009] Furthermore, the number of the heating cones is three; the sample is embedded in the sample box, exposing three adjacent surfaces with the same vertex as the test heating surfaces; the three heating cones are placed in combination, facing the three test heating surfaces one by one, forming a three-sided structure with the same angles as the three test heating surfaces; the thermal insulation baffle is spliced ​​by three thermal insulation panels, forming a three-sided structure with the same angles as the three test heating surfaces, and is placed between the corresponding test heating surface and the heating cone before the experiment.

[0010] Furthermore, the measuring unit includes an infrared thermometer, an electronic balance, a heat flux meter and a camera; the infrared thermometer is used to measure the surface temperature of the sample; the sample box embedded with the sample is placed on the electronic balance, and the electronic balance is used to measure the mass of the sample; the heat flux meter is used to measure the heat flux of the heating cone; and the camera is used to monitor the state of the sample (whether it is on fire).

[0011] Furthermore, when calibrating the heat flux, the heat flux meter is placed directly in front of the center of the heating cone.

[0012] Furthermore, it also includes a data acquisition unit; the data acquisition unit includes a terminal device, an acquisition module and a data conversion module; the acquisition module is used to collect radiation heat flux, and the collected signal is converted into a data format by the data conversion module and transmitted to the terminal device; the terminal device is connected to the control unit, and the heat flow signal is fed back to the control unit, and the control unit controls the heating cone accordingly.

[0013] The present invention also provides a testing method for the above-mentioned multi-faceted radiation accelerated pyrolysis and combustion experimental device, which is used to determine the critical heat flux of a sample, and the method is: keep the angle of the sample test heating surface unchanged, and conduct a critical heat flux experiment: when the heat fluxes of each surface are the same, gradually reduce the heat flux of the heating cone while ensuring ignition until the sample cannot ignite, and then further refine the heat flux variable to accurately determine the critical ignition heat flux, and finally obtain a single critical heat flux that is the same for each surface; when the heat fluxes of each surface are different, fix the heat flux of the heating cone corresponding to one surface, and regularly change the heat fluxes of the heating cones corresponding to other surfaces to determine the critical heating conditions, and finally obtain different combined critical heat fluxes for each surface; regularly change the angle of the sample test heating surface and conduct a critical heat flux experiment to determine the different critical heat fluxes of the sample at each angle.

[0014] The present invention also provides a testing method for the above-mentioned multi-faceted radiation accelerated pyrolysis and combustion experimental device, which is used for pyrolysis and ignition experiments. The method is: within the range of ignition heat flow, regularly change the angle of the sample test heating surface and the heat flux size of the corresponding heating cone on each side (including the same and different heat fluxes on each side) to carry out pyrolysis and ignition experiments, record the ignition time, critical temperature (i.e., the edge temperature of the sample heated on two sides at the moment of ignition or the top angle temperature of the sample heated on three sides at the moment of ignition), and critical mass loss rate (i.e., the mass loss rate of the sample at the moment of ignition) under different heating conditions, and analyze the change pattern of ignition time with heat flow.

[0015] The beneficial effects of the present invention are as follows: in view of the defect that existing standard instruments (such as cone calorimeters, etc.) cannot realize multi-faceted radiation heat flow, the present invention provides a multi-faceted radiation accelerated pyrolysis and combustion experimental device and test method, combines the heating cones of a single radiation heat flow, and realizes the quantitative determination of the temperature and mass of the sample to be tested under multi-faceted heating conditions by changing the number and combination of heating cones. The device is reasonably designed and has an appropriate size, which is completely suitable for laboratory mesoscale experiments. The device is simple and easy to operate, with high reliability, and can realize ignition experiments of heating two sides of edges at different angles and three sides of vertices at different angles, and the test results have high repeatability and accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the structure of the multi-faceted radiation accelerated pyrolysis and combustion experimental device; Figure 2 It is a schematic diagram of the structure of placing samples in a sample box. The left picture shows a sample box with a double test heating surface sample with 120° edges, and the right picture shows a sample box with a triple test heating surface sample with 90° edges. Figure 3 It is a schematic diagram of the structure of a heating unit with two heating cones and a sample; Figure 4 It is a schematic diagram of the structure of a heating unit with three heating cones and a sample; Figure 5It is a schematic diagram of the structure of the heat flow meter; Figure 6 It is a schematic diagram of the structure of samples with edges (two-dimensional) and corners (three-dimensional) at different angles; Figure 7 This is the data diagram of the 90° angle and surface temperature measured in the pyrolysis and ignition experiment of PMMA samples under SET1 working conditions; Figure 8 This is the mass loss rate data graph measured by the pyrolysis and ignition experiment of PMMA samples under SET1 working conditions; Fig. 9 This is the 90° angle and surface temperature data graph measured in the pyrolysis and ignition test of PMMA samples under SET2 conditions; Fig.10 This is the mass loss rate data graph measured by the pyrolysis and ignition experiment of PMMA samples under SET2 working conditions; Fig.11 This is the data graph of critical temperature and critical mass loss rate measured in experiments under SET1, SET2 and single-side heating; Fig.12 This is a graph showing the relationship between ignition time and heat flow measured in experiments under SET1, SET2 and single-sided heating. DETAILED DESCRIPTION

[0017] The specific implementation of the present invention is described below with reference to the accompanying drawings.

[0018] like Figure 1 As shown, this embodiment provides a multi-surface radiation accelerated pyrolysis and combustion experimental device, including a heating unit, a measuring unit, a data acquisition unit 3 and a control unit 4.

[0019] The heating unit includes a plurality of heating cones 11 and a sample box 12 .

[0020] The sample A is embedded in the sample box 12, with only a plurality of surfaces exposed as test heating surfaces. The plurality of heating cones 11 correspond to the plurality of test heating surfaces of the sample one by one and heat them.

[0021] Specifically, the heating cone 11 is a standard heater in the cone calorimeter. Two or three heating cones can be used according to the needs and the relative angle can be flexibly set. The heating cone uses an electric heating wire with a diameter of 10 mm and can provide 0~100 kW / m 2 Radiant heat flow. The radiant heating surface of the heating cone 11 is a heating port with a diameter of 15 cm, and there is an exhaust port with a diameter of 5 cm at the top of the cone. Two K-type thermocouples with a diameter of 1 mm are provided on the electric heating coil of the heating cone 11, and the real-time temperature signal of the monitored electric heating coil can be fed back to the control unit 4 through the data acquisition unit 3 and displayed in real time.

[0022] As shown in FIG2 , during the experiment, the sample A needs to be placed in a sample box 12. The sample box 12 is made of low thermal conductivity ceramic fiber material (heat resistant temperature is 1000°C). The required sample size and angle are customized according to the angles of the experimental sample, so that during the experiment, only the test heating surface of the sample is heated by external thermal radiation, and the other sides are in an insulated state in the sample box.

[0023] like Figure 3 and 4 As shown, the heating unit further includes a heat insulation baffle 13. The heat insulation baffle 13 is used to be placed between the test heating surface and the heating cone 11 before the experiment to isolate the radiation of the heating cone 11.

[0024] Specifically, the heat insulation baffle 13 is made of high temperature resistant ceramic fiberboard, and its size is customized according to the size of the heating cone 11 and the angle required for the experiment. Before the experiment, the heat insulation baffle 13 needs to be placed between the heating cone 11 and the sample A to prevent the sample A from being heated before the experiment begins. After the heat flux calibration is completed, the heat insulation baffle 13 is placed, and then the sample box 12 containing the sample A is placed. When the heat insulation baffle 13 is pulled out, the experimental test begins.

[0025] like Figure 3 As shown, in a specific embodiment, the number of heating cones 11 is two, and the combination of two heating cones 11 can be used to study the pyrolysis and ignition behavior of solid combustibles under heating with edges at different angles. Specifically, sample A is embedded in the sample box 12, exposing two adjacent surfaces with the same edge as the test heating surface. The two heating cones 11 are placed in combination, facing the two test heating surfaces one by one, forming a double-sided structure with the same edge angle as the two test heating surfaces (60°, 120°). The heat insulation baffle 13 is spliced ​​by two heat insulation panels to form a double-sided structure with the same edge angle as the two test heating surfaces, and is placed between the corresponding test heating surface and the heating cone 11 before the experiment.

[0026] like Figure 4 As shown, in a specific embodiment, the number of heating cones 11 is three, and the three heating cones 11 are placed in combination to achieve three-sided heating of the sample at different angles. Specifically, sample A is embedded in the sample box 12, exposing three adjacent faces with the same vertex as the test heating surface. The three heating cones 11 are placed in combination, facing the three test heating surfaces one by one, forming a three-sided structure with the same angle (90°) as the three test heating surfaces. The heat insulation baffle 13 is spliced ​​by three heat insulation panels to form a three-sided structure with the same angle as the three test heating surfaces, and is placed between the corresponding test heating surface and the heating cone 11 before the experiment.

[0027] In addition, if Figure 1As shown, the heating unit further includes a stainless steel bracket 14. The stainless steel bracket 14 is composed of a 150 mm×150 mm×13 mm aluminum optical plate and a telescopic folding support frame with adjustable height, and is used to place the sample box, and the height can be adjusted according to experimental needs.

[0028] like Figure 1 As shown, the measuring unit includes an infrared thermometer 21 , an electronic balance 22 , a heat flow meter and a camera 23 .

[0029] The infrared thermometer 21 is used to measure the surface temperature of the sample. In this embodiment, the infrared thermometer is Hikvision Micro-Image H16PRO, with an accuracy of 0.1 °C and a range of 0-550 °C. It can measure the temperature of target points, lines, frames and circles, and has visible light, thermal imaging, dual light fusion and picture-in-picture modes, meeting the temperature measurement conditions required for the experiment.

[0030] The sample box 12 embedded with the sample A is placed on the electronic balance 22, which is used to measure the mass of the sample A. In this embodiment, the electronic balance is Sartorius GL6202i-ISCN, with an accuracy of 0.01 g, a measuring range of 10 kg, and a collection frequency of 1 Hz, which can monitor mass changes in real time.

[0031] The heat flow meter is used to measure the heat flow of the heating cone 11. In this embodiment, the heat flow meter is a water-cooled Schmidt-Boelter with a range of 0-100 kW / m 2 , accuracy is 0.001 kW / m 2 , response 5.243 (kW / m 2 ) / mV, the response time is 80 ms, the repeatability is ±0.5%, and the diameter of the radiation receiving target is 12.5 mm. The surface of the heat flux meter is covered with a durable matte black coating with an absorptivity of 0.92, as shown in Figure 5. When calibrating the heat flux, the heat flux meter is placed in front of the center of the heating cone and connected to the controller to feedback the heat flux signal for real-time monitoring and measurement of the heat flux to achieve the target heat flux required for the experiment.

[0032] The camera 23 is used to monitor the status of the sample A, specifically to monitor whether the sample A is on fire.

[0033] The data acquisition unit 3 includes a terminal device, an acquisition module and a data conversion module. The acquisition module is used to acquire the heat flow signal of the heat flow meter and the temperature signal of the heating cone thermocouple. The acquired signals are converted into data format by the data conversion module and transmitted to the terminal device. The terminal device is connected to the control unit 4 and feeds back the heat flow signal and temperature signal to the control unit 4.

[0034] Specifically, the terminal device is a computer, which can be an ordinary computer. The acquisition module is a C-7018 module, which supports multi-channel data acquisition and can collect multiple data of the same type at the same time. The acquisition module is powered by a 220 V AC to 12 V DC transformer. The data conversion module is an A\D data conversion module. The data acquisition object is radiation heat flux, and the data acquisition type corresponding to the radiation heat flux is set to voltage type. The set voltage input range should not be too large, otherwise it will affect the accuracy of the heat flux data. The heat flux output and heat flux meter range of this experimental device are both 0~100 kW / m 2 The response is 5.243 (kW / m 2 ) / mV, the voltage received by the module does not exceed 20 mV, so the acquisition module sets the voltage range to 0~50 mV. The signal of the acquisition module is converted into data format by the A\D conversion module and transmitted to the computer. The computer collects the real-time voltage data of the C-7018 module through the corresponding port based on the data acquisition program, and converts the voltage data into heat flow data according to the responsiveness of the heat flow meter. The data acquisition frequency is adjustable. In this embodiment, the data acquisition frequency is 1 Hz.

[0035] The control unit 4 controls the heating cone 11 to heat according to the feedback heat flow signal. At the same time, the control unit 4 also displays the feedback temperature signal in real time.

[0036] Specifically, the control unit 4 is mainly composed of a PID temperature controller, a power switch and a heating switch. The PID temperature controller can receive the feedback signal of the thermocouple at the electric heating coil collected by the data acquisition unit 3, and adjust the power of the heating cone according to the real-time temperature of the electric heating coil to meet the heating wire temperature and radiation heat flow requirements required by the experiment. The power switch controls the power of the entire control unit 4. The heating switch controls the power of the heating cone 11. When the heating switch is turned on, the electric heating coil starts heating according to the setting of the thermostat; when the heating switch is turned off, the electric heating coil stops heating immediately, and the thermostat loses control of the electric heating coil.

[0037] This embodiment also provides a test method for a multi-faceted radiation accelerated pyrolysis and combustion experimental device, including critical heat flux determination and ignition time measurement experiments.

[0038] The specific method for determining the critical heat flux is as follows: keep the angle of the sample test heating surface unchanged and conduct a critical heat flux experiment: when the heat flux of each surface is the same, gradually reduce the heat flux of the heating cone while ensuring ignition until the sample cannot ignite, and then further refine the heat flux variable to accurately determine the critical ignition heat flux, and finally obtain a single critical heat flux that is the same for each surface; when the heat flux of each surface is different, fix the heat flux of the corresponding heating cone on one surface, and regularly change the heat flux of the corresponding heating cones on other surfaces to determine the critical heating conditions, and finally obtain different combined critical heat fluxes on each surface. Regularly change the angle of the sample test heating surface and conduct a critical heat flux experiment to determine the different critical heat fluxes at each angle of the sample.

[0039] The specific method of the ignition time measurement experiment is: within the range of ignition heat flux, regularly change the angle of the sample test heating surface and the heat flux of the corresponding heating cone on each side (including the same and different heat fluxes on each side) to carry out pyrolysis ignition experiments, record the ignition time under different heating conditions, critical temperature (i.e. the edge temperature of the sample heated on two sides at the moment of ignition or the top angle temperature of the sample heated on three sides at the moment of ignition), critical mass loss rate (i.e. the mass loss rate of the sample at the moment of ignition), and analyze the change pattern of ignition time with heat flux.

[0040] Among them, the edge angles include 30°, 60°, 90°, 120°, 150°, and 180° (flat plate, reference group), and the vertex angles include two types: three faces perpendicular to each other, two faces perpendicular and the third face is 30°, 45°, and 60°. The samples are cut by laser cutting, and the side length of each face is 4 cm. The processed samples are uniform in size, the thickness error is no more than 0.1 mm, and the material is uniform and free of impurities, as shown in Figure 6.

[0041] The specific method of heat flux calibration is: determine the horizontal distance between the sample and the radiation heating cone according to the heat flux conditions required for the experiment, fix the heat flux meter on the central axis of the radiation source and make the distance from the radiation port the same as the distance from the heated surface of the sample, and adjust the set temperature of the temperature controller according to the real-time heat flux of the acquisition system to achieve different heat fluxes. Wait for the system to run stably for 20 minutes, and allow the measured target heat flux to be within ±0.2 kW / m 2 The error range of the sample is 0.04. Then, the heat flux at the four corners and the center of the sample is measured respectively. The heat flux attenuation at the four corners should be less than 4% of the heat flux measured at the center. During the entire calibration process, there must be no obvious external airflow interference, the ambient temperature must be stable, and there must be no interference from other heating sources near the heating cone to ensure the uniformity and stability of the heat flux at the surface of the sample. To ensure the accuracy of the experimental heat flux, each heat flux heating condition must be calibrated at least three times.

[0042] In a specific embodiment, the use of the device and typical test results are described by taking two vertical radiation heating cones to heat the 90° edges of a PMMA cube sample for pyrolysis and ignition as an example.

[0043] Two heating conditions were set up in the experiment: one was that the two heating cones radiated the same heat flux to the adjacent surfaces of the sample, which was set as SET1; the other was that the first heating cone was kept at 20 kW / m 2 The heat flux of the first heating cone is kept constant, and the second heating cone is set to a different heat flux, which is set as SET2. The two groups of working conditions SET1 and SET2 are compared to study the effect of the heat flux on the accelerated pyrolysis of edges and corners. The experimental measurement parameters include the edge and surface temperature of the sample, mass loss and ignition time. Use an infrared thermometer to set multiple temperature measurement points on the edge and heated surface of the sample, such as Figure 4 As shown, the sample surface temperature is recorded and the real-time mass of the sample is measured using an electronic balance. The ignition time is the time from the start of heating of the sample to the appearance of a continuous flame, which is recorded by a camera and verified by the inflection point of the surface temperature rise. The camera captures the initial ignition location, flashover, gas phase flame spread and other phenomena, and determines the critical temperature and critical mass flow rate through the surface temperature, mass loss rate and ignition time.

[0044] Before the experiment begins, place the height-adjusted stainless steel bracket at a suitable distance from the heating cone and place a radiation baffle. Then place the sample box containing the sample horizontally on the electronic balance on the stainless steel bracket, so that the distance between the heated surface of the sample and the heating cone meets the set distance, and keep the center of the sample and the central axis of the heating cone on the same horizontal line. Three groups of effective experiments were carried out under the same working conditions to improve the accuracy of the measured temperature values. To ensure the authenticity and accuracy of the experimental data, the temperature data and quality data were recorded simultaneously.

[0045] The edge and surface temperature data and mass loss rate under SET1 condition are shown in Figures 7 and 8, and the edge and surface temperature data and mass loss rate under SET2 condition are shown in Figures 9 and Fig.10 The critical temperature and critical mass loss rate measured under SET1, SET2 and single-side heating conditions are shown in Figure 2. Fig.11 As shown in a and b. It can be seen from the figure that the critical temperature remains almost unchanged under different heating conditions, fluctuating within a narrow critical temperature band; and the temperature of the two heated surfaces of the samples tested by SET1 and SET2 at the time of ignition (T_surface) is much lower than the corner temperature, that is, the critical temperature (T_critical). Under single-sided heating conditions, the critical mass loss rate does not change much with the heat flux and can be considered as a constant value; while under double-sided heating conditions, the critical mass loss rates of SET1 and SET2 both increase approximately linearly with the heat flux. The -0.5 power of the ignition time measured in the experiments under SET1, SET2 and single-sided heating conditions ( t-0.5ig ) is related to heat flow as Fig.12 As shown in the figure, under SET1 and single-sided heating conditions, t- 0.5ig It has a good linear relationship with the heating heat flow, and under SET2 heating conditions, t-0.5ig It has a nonlinear relationship with the heating heat flux.

[0046] In the present invention, unless otherwise specified, the scientific and technical terms used herein have the meanings commonly understood by those skilled in the art. In addition, the materials and operating steps used herein are the materials and conventional steps widely used in the corresponding fields.

[0047] It should be noted that the terms such as "upper", "lower", "left", "right", "front", "back", etc. cited in the invention are only for the convenience of description and are not used to limit the scope of implementation of the present invention. Changes or adjustments in their relative relationships should be regarded as the scope of implementation of the present invention without substantially changing the technical content.

[0048] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A multi-faceted radiation accelerated pyrolysis and combustion experimental device, characterized in that: It includes a heating unit, a control unit and a measuring unit; The heating unit includes a plurality of heating cones and a sample box; The sample is embedded in the sample box, with only a few surfaces exposed as test heating surfaces; The plurality of heating cones correspond to the plurality of test heating surfaces of the sample one by one and heat the surfaces; The control unit is used to control the heating of the heating cone; The measuring unit is used to measure the surface temperature of the sample, the mass of the sample and the heat flow of the heating cone, and monitor the status of the sample.

2. The multi-surface radiation accelerated pyrolysis and combustion experimental device according to claim 1, characterized in that: The heating unit also includes a heat insulation baffle; The heat insulation baffle is used to be placed between the test heating surface and the heating cone before the experiment to isolate the radiation of the heating cone.

3. The multi-surface radiation accelerated pyrolysis and combustion experimental device according to claim 2, characterized in that: The materials of the heat insulation baffle and the sample box are both high temperature resistant ceramic fibers.

4. The multi-surface radiation accelerated pyrolysis and combustion experimental device according to claim 2, characterized in that: The number of the heating cones is two; The sample is embedded in the sample box, exposing two adjacent surfaces with the same edge as the test heating surface; Two heating cones are placed in combination, facing the two test heating surfaces one by one, forming a double-sided structure with edges having the same angle as the two test heating surfaces; The heat insulation baffle is formed by splicing two heat insulation panels to form a double-sided structure with edges having the same angle as the two test heating surfaces, and is placed between the corresponding test heating surface and the heating cone before the experiment.

5. The multi-surface radiation accelerated pyrolysis and combustion experimental device according to claim 2, characterized in that: The number of the heating cones is three; The sample is embedded in the sample box, exposing three adjacent faces with the same vertex as the test heating faces; The three heating cones are placed in combination, facing the three test heating surfaces one by one, forming a three-sided structure with the same angles as the three test heating surfaces; The heat insulation baffle is composed of three heat insulation panels spliced ​​together to form a three-sided structure with the same angles as the three test heating surfaces. It is placed between the corresponding test heating surface and the heating cone before the experiment.

6. The multi-surface radiation accelerated pyrolysis and combustion experimental device according to claim 1, characterized in that: The measuring unit includes an infrared thermometer, an electronic balance, a heat flow meter and a camera; Infrared thermometer is used to measure the surface temperature of the sample; The sample box with the sample embedded in it is placed on an electronic balance, which is used to measure the mass of the sample; The heat flow meter is used to measure the heat flow of the heating cone; The camera is used to monitor the status of the sample.

7. The multi-surface radiation accelerated pyrolysis and combustion experimental device according to claim 6, characterized in that: When calibrating the heat flux, the heat flux meter is placed directly in front of the center of the heating cone.

8. The multi-surface radiation accelerated pyrolysis and combustion experimental device according to claim 1, characterized in that: Also includes a data acquisition unit; The data acquisition unit includes a terminal device, an acquisition module and a data conversion module; The acquisition module is used to collect radiation heat flow, and the collected signal is converted into data format by the data conversion module and transmitted to the terminal device; The terminal device is connected to the control unit and feeds back the heat flow signal to the control unit.

9. The testing method of the multi-surface radiation accelerated pyrolysis and combustion experimental device according to any one of claims 1 to 8, characterized in that: Used to determine the critical heat flux of the sample, the method is: Keep the angle of the sample test heating surface unchanged and conduct the critical heat flux experiment: When the heat flux on each surface is the same, the heat flux of the heating cone is gradually reduced until the sample cannot ignite while ensuring ignition. The heat flux variable is further refined to accurately determine the critical ignition heat flux, and finally a single critical heat flux that is the same on each surface is obtained. When the heat fluxes of each surface are different, the heat flux of the heating cone corresponding to one surface is fixed, and the heat fluxes of the heating cones corresponding to other surfaces are changed regularly to determine the critical heating conditions, and finally different combined critical heat fluxes of each surface are obtained; The angle of the sample test heating surface is regularly changed and a critical heat flux experiment is performed to determine the different critical heat fluxes of the sample at each angle.

10. The testing method of the multi-surface radiation accelerated pyrolysis and combustion experimental device according to any one of claims 1 to 8, characterized in that: For pyrolysis ignition experiment, the method is: The pyrolysis ignition experiment was carried out by regularly changing the angle of the sample test heating surface and the heat flux of the corresponding heating cone on each surface within the range of ignition heat flux. The ignition time, critical temperature and critical mass loss rate under different heating conditions were recorded, and the change of ignition time with heat flux was analyzed.

Images