Dual heat release rate measuring platform integrating temperature difference method and oxygen consumption method and measuring method thereof

Abstract

The invention relates to a dual heat release rate measuring platform integrating a temperature difference method and an oxygen consumption method and a measuring method thereof. The measuring platform comprises an oscilloscope, thermocouple assemblies, a cone calorimeter, a sample holder and an objective table, the sample holder is fixed on the objective table, the cone calorimeter is located right above the sample holder, and the thermocouple assemblies are dispersedly arranged on the pipe wall and the center of a smoke pipeline of the cone calorimeter and connected with the oscilloscope. The measured temperature is corrected through the oscilloscope and the thermocouple assembly, the relation curve of the temperature difference and the heat release rate can be calculated and drawn in real time after data processing, the delay defect of a traditional cone calorimeter is overcome, heat release rate parameters better conforming to reality can be obtained, and it is ensured that the test result is more accurate and reliable. The measuring platform has the advantages of simple structure, convenience and quickness in construction, low cost, easiness in operation and the like.

Description

Technical Field

[0001] The present invention relates to multiple technical fields such as new energy batteries, measuring instruments and fire emergency response, and in particular to a dual heat release rate measurement platform integrating a temperature difference method and an oxygen consumption method and a measurement method thereof. Background Art

[0002] With the advancement of energy storage technology, particularly the widespread application of lithium-ion batteries in portable electronic devices, electric vehicles, and energy storage systems, battery safety issues are receiving increasing attention and attention. Under abnormal conditions such as overcharging, over-discharging, and short-circuiting, batteries are prone to thermal runaway, leading to a rapid increase in temperature, fire or explosion, and significant economic losses. Research on thermal runaway, primarily focusing on lithium-ion batteries, has found that the heat release rate (HRR) during combustion and explosion processes is a key parameter for assessing fire hazard. Related research results show that the HRR is highly proportional to the burning rate of a fire. The HRR reflects the speed and magnitude of heat released by the fire source, that is, the heat release capacity of the fire source. Generally, a higher HRR indicates greater heat feedback to the material surface during combustion, faster thermal decomposition of the material, and increased production of volatile combustibles, ultimately accelerating flame propagation. Therefore, the HRR is a key parameter for assessing the burning rate and heat release of a fire.

[0003] Based on these conclusions and to gain a deeper understanding of the actual conditions of fire, researchers invented the cone calorimeter. This new-generation instrument, based on the oxygen consumption method, measures the combustion performance of polymer materials in a fire. It can measure a variety of combustion parameters of combustible materials, including heat release rate (HRR), total heat release (THR), effective combustion (EHC), time to ignition (TTI), smoke and toxicity parameters, and mass change (MLR). Due to its minimal susceptibility to external factors and excellent correlation with large-scale experimental results, the cone calorimeter has been widely used in combustion research across various fields.

[0004] The inventor's research team has developed a series of detection equipment based on cone calorimeters, such as CN114217007B and CN118655266A. In actual use, it was found that these detection equipment still have the following problems: (1) Some test samples (such as lithium batteries) release oxygen during combustion, which causes errors in the heat release rate measured by the cone calorimeter based on the oxygen consumption method, resulting in inaccurate HRR peak measurement; (2) The existing cone calorimeter can only simulate the general situation of fire by monitoring the heat release rate, and lacks an accurate test method for the heat release rate of sudden fires. In addition, for fires with a faster development rate, the real-time HRR test has a delay; (3) A set of temperature and pressure acquisition devices separately set on the flue gas pipe of the cone calorimeter cannot fully monitor and record the temperature difference of the cone calorimeter tube wall during combustion; (4) The existing cone calorimeter is mainly used for combustion experiments of small-sized samples. The test results have high accuracy, but when facing large-sized samples, it requires more manpower and material resources. Summary of the Invention

[0005] The primary purpose of the present invention is to address the aforementioned issues with the prior art. By utilizing multiple thermocouple devices and an improved measurement method, the relationship between real-time temperature differences and heat release rates is better calibrated. This not only overcomes the time delay inherent in conventional cone calorimeters, but also enables the use of more accurate temperature difference data to produce a more realistic heat release rate curve, ensuring more accurate and reliable test results. To achieve this objective, the present invention employs the following technical solutions: A dual heat release rate measurement platform integrating the temperature difference method and the oxygen consumption method includes a cone calorimeter 3, a thermocouple assembly 2, and a display and data processing device. The data acquisition ends of the thermocouple assembly 2 are distributed at different positions inside the flue gas duct of the cone calorimeter 3 and are used to collect temperature data of corresponding parts of the cone calorimeter 3 in real time; the output end of the thermocouple assembly 2 is connected to the display and data processing device for data processing and result display.

[0006] In the above solution, the thermocouple assembly 2 includes at least two sets of thermocouple devices, one of which is arranged at the center of the cone calorimeter flue gas duct, and the remaining thermocouple devices are arranged on the inner wall of the cone calorimeter flue gas duct.

[0007] As a preferred solution, the number of thermocouples is five, with one thermocouple positioned at the center of the cone calorimeter flue gas duct, and the remaining four symmetrically distributed along the upper, lower, left, and right walls of the cone calorimeter flue gas duct. Multiple thermocouples positioned within the flue gas duct enable more comprehensive temperature data to be collected, leading to more accurate combustion parameters such as the heat release rate.

[0008] In the above solution, each thermocouple device in the thermocouple assembly 2 includes a measuring end 36, an insulating tube 37, and a locking sleeve 38. The insulating tube 37 is sleeved on the tail of the measuring end 36 and fixed to the flue gas duct or fixing device through the locking sleeve 38.

[0009] In the above embodiment, the display and data processing device includes an oscilloscope 1. A thermocouple assembly 2 is connected to the oscilloscope 1 via an oscilloscope cable 21. The panel of the oscilloscope 1 includes function buttons and display components such as an oscilloscope switch control 20, an integrated logic analysis button 22, an oscilloscope display 23, and a thermal resistor data acquisition screen 24.

[0010] In the above solution, the measurement platform further includes a sample holder 4 and a stage 5 . The sample holder 4 is fixedly connected to the stage 5 , and the cone calorimeter 3 is fixed above the sample holder 4 at a certain distance (ie suspended in the air).

[0011] The second object of the present invention is to provide a method for using the dual heat release rate measurement platform integrating the temperature difference method and the oxygen consumption method, comprising: starting the cone calorimeter for testing, the flue gas generated by the combustion of the sample to be tested flows through the flue gas duct, the thermocouple assembly 2 collects the temperature data of different parts of the flue gas duct and transmits it to the display and data processing device, the display and data processing device calculates the temperature data according to the linear mapping relationship between the temperature difference and the HRR (HRR=η(T n -T0), where η is the combustion efficiency factor, T n The real-time HRR curve is fitted (where T is the temperature measured by the thermocouple assembly and T0 is the room temperature).

[0012] In the above scheme, before formal testing, a standard sample (such as methane) is used as the raw material, and testing is performed according to the above method to verify the specific value of η in the formula. Research has shown that the heat release rate is proportional to the temperature difference (ΔT). Determining the proportionality coefficient (η) between the two can be used to calculate and plot the real-time HRR curve. Therefore, standard sample calibration was used to obtain an accurate proportionality coefficient, which was used in subsequent experiments.

[0013] In the above scheme, the temperature T measured by each thermocouple device in the thermocouple assembly 2 is n The temperature difference ΔT is calculated by subtracting the room temperature T0. The corresponding HRR value is calculated based on the calibrated η (combustion efficiency factor). The average value of these HRRs is obtained and the real-time HRR curve is plotted with the temperature difference ΔT as the horizontal axis and the average value of HRR as the vertical axis.

[0014] Specifically, the average value includes the arithmetic mean, geometric mean, root mean square mean, harmonic mean, and weighted mean, preferably the arithmetic mean.

[0015] The dual heat release rate measurement platform described in this invention, integrating temperature difference and oxygen consumption methods, can better handle the relationship between real-time temperature and heat release rate, providing a more sensitive response to heat release rate peaks and during their rise and fall. This not only compensates for the time delay of cone calorimeters, but also allows for more accurate fitting of heat release rate curves based on temperature difference data. Compared with existing similar technologies or products, the advantages of this invention are primarily reflected in the following aspects: (1) The dual heat release rate measurement platform integrating the temperature difference method and the oxygen consumption method provided by the present invention has the advantages of simple structure, convenient and fast construction, low cost, and easy operation.

[0016] (2) The present invention combines the advantages of the oxygen consumption method and the temperature difference method, and can more accurately simulate and measure the heat release rate of batteries and other materials during thermal runaway.

[0017] (3) The present invention can simultaneously monitor oxygen consumption and temperature changes, thereby providing a more comprehensive analysis of thermal runaway characteristics, which helps to better understand the behavior of batteries in different combustion stages, thereby providing more accurate data support for battery design and safe application.

[0018] (4) The present invention can accurately and in real time detect combustion performance parameters such as the heat release rate and total heat release in rapid fires that release oxygen (e.g., lithium battery combustion). It can more sensitively reflect the peak and changes in the heat release rate, facilitating a better evaluation of combustion behavior in rapid fires. This is an advantage of the temperature difference method, as it is independent of oxygen concentration and the temperature responds quickly to changes in the combustion reaction, resulting in more accurate values. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of the overall structure of the dual heat release rate measurement platform integrating the temperature difference method and the oxygen consumption method according to the present invention; Figure 2 Schematic diagram of the cone calorimeter structure of the dual heat release rate measurement platform integrating the temperature difference method and the oxygen consumption method according to the present invention; Figure 3 This is a schematic diagram of the sample holder structure of the dual heat release rate measurement platform integrating the temperature difference method and the oxygen consumption method according to the present invention; Figure 4 This is a schematic diagram of the oscilloscope structure of the dual heat release rate measurement platform integrating the temperature difference method and the oxygen consumption method according to the present invention; Figure 5 Schematic diagram of the stage of the dual heat release rate measurement platform integrating the temperature difference method and the oxygen consumption method according to the present invention; Figure 6 This is a schematic diagram of the installation position of the thermocouple device of the dual heat release rate measurement platform integrating the temperature difference method and the oxygen consumption method of the present invention; Figure 7 This is a schematic diagram of the structure of the thermocouple device of the dual heat release rate measurement platform integrating the temperature difference method and the oxygen consumption method described in the present invention.

[0020] Reference numerals: 1 oscilloscope, 2 thermocouple assembly, 3 cone calorimeter, 4 sample holder, 5 stage, 6 temperature and pressure collection point, 7 blower, 8 laser beam photometer, 9 gas collection point, 10 smoke sample filter, 11 smoke hood, 12 high temperature protective cover, 13 fixed mold, 14 slot, 15 base, 16 concave table, 17 steel plate, 18 mica plate fixture, 19 handle, 20 oscilloscope switch control device, 21 oscilloscope connecting line , 22 integrated logic analysis button, 23 oscilloscope display, 24 thermal resistance data acquisition screen, 25 igniter, 26 item rack, 27 electronic scale, 28 base, 29 bracket, 30 thermocouple installation position, 31 left thermocouple device, 32 upper thermocouple device, 33 right thermocouple device, 34 middle thermocouple device, 35 lower thermocouple device, 36 measuring end, 37 insulating tube, 38 locking sleeve, 39 flue gas duct, 40 junction box. DETAILED DESCRIPTION

[0021] In order to enable those skilled in the art to fully understand the technical solutions and beneficial effects of the present invention, further description will be given below in conjunction with specific embodiments and drawings.

[0022] like Figure 1-7 The dual heat release rate measurement platform integrating the temperature difference method and the oxygen consumption method shown in the figure mainly includes an oscilloscope 1, a thermocouple assembly 2, a cone calorimeter 3, a sample holder 4, and a stage 5. The oscilloscope 1 is mainly used to process and display the real-time temperature and other data measured by the thermocouple assembly 2, and the cone calorimeter 3 is mainly used to collect and record the flue gas and other data generated by the combustion of the sample to be tested; the sample holder 4 is mainly used to place and fix the sample to be tested, and the stage 5 is mainly used to provide an ignition place for the sample to be tested.

[0023] like Figure 2As shown, the cone calorimeter 3 adopts a cabinet-style design (comprising multiple cabinets) and primarily includes a temperature and pressure sampling point 6, a blower 7, a laser beam photometer 8, a gas sampling point 9, a smoke sample filter 10, a smoke hood 11, and a high-temperature protective cover 12. The smoke hood 11 is fixedly connected to the high-temperature protective cover 12. A flue gas duct is connected to the rear of the smoke hood 11, where the temperature and pressure sampling point 6, laser beam photometer 8, gas sampling point 9, and smoke sample filter 10 are located. The blower 7 is connected to the flue gas duct and drives the flue gas in a directional flow. The cone calorimeter 3 is equipped with a software operating system primarily for controlling equipment operation and recording and analyzing test results, including heat release rate, flue gas flow rate, C coefficient, sample ignition and extinction time, total oxygen consumption, total smoke generation, mass loss rate, total heat release, effective heat of combustion, carbon dioxide generation, and carbon monoxide generation.

[0024] like Figure 3 As shown, the sample holder 4 includes a fixed mold 13, a slot 14, a base 15, a recess 16 (100mm*100mm), a steel plate 17 (100mm*100mm), a mica plate clamp 18, and a handle 19. The steel plate 17 is horizontally positioned within the recess 16, and the battery sample to be tested is secured within and positioned on the steel plate 17. The base 15 is provided with a slot 14, into which the fixed mold 13 is secured. A handle 19 is provided on the right side of the base 15, allowing the entire sample holder 4 to be conveniently transferred to the tray of the electronic balance 27. Mica plate clamps 18 are provided on both sides of the handle of the base 15. The battery to be tested and the thermocouple attached to its surface are secured to the recess 16 on top of the fixed mold 13 via the mica plate clamps 18, preventing the battery to be tested from shifting or the thermocouple from falling off during testing.

[0025] like Figure 4 As shown, oscilloscope 1 includes an oscilloscope connection cable 21, an oscilloscope switch control device 20, an integrated logic analysis button 22, an oscilloscope display screen 23, and a thermal resistor data acquisition screen 24. Thermocouple assembly 2 is connected to oscilloscope 1 via oscilloscope connection cable 21. Its real-time measured temperature data is transmitted to oscilloscope 1 and, after processing, displayed on oscilloscope display screen 23 and thermal resistor data acquisition screen 24. The integrated logic analysis button 22 is primarily used for switching and analyzing data.

[0026] like Figure 5As shown, the stage 5 includes an igniter 25, an item rack 26, an electronic scale 27, a base 28, and a bracket 29. The bracket 29 is the main mounting body, and the remaining components are directly or indirectly fixed to the bracket 29. Specifically, the base 28 is mounted on the bracket 29, the electronic scale 27 is placed on the base 28, the item rack 26 is placed on the tray (made of stainless steel) of the electronic scale 27, and the sample rack 4 is placed on the item rack 26. The igniter 25 is suspended and fixed directly above the sample rack 4 and the item rack 26.

[0027] like Figure 6-7 As shown, the thermocouple assembly 2 includes five thermocouples, namely the left thermocouple device 31, the upper thermocouple device 32, the right thermocouple device 33, the middle thermocouple device 34, and the lower thermocouple device 35. These thermocouple devices are fixedly installed at the top, bottom, left, right and center of the flue gas duct of the cone calorimeter (corresponding to Figure 6 Each thermocouple device has the same structure, including a measuring end 36 and an insulating tube 37. The measuring end 36 includes a thermoelectrode, a thermocouple wire, and a porcelain bead. The insulating tube 37 is mounted on the end of the measuring end 36. A locking sleeve 38 secures the corresponding thermocouple device in the flue gas duct 39. The junction box 40 is connected to the oscilloscope 1 via the oscilloscope connection cable 21.

[0028] The method of using the dual heat release rate measurement platform integrating temperature difference method and oxygen consumption method is as follows: Turn on the cone calorimeter main unit and perform a series of tests and calibrations according to the standard method ISO5660-1. Open the high-temperature protective cover 12 of the cone calorimeter, place the sample to be tested into the sample rack 4 and then place it on the item rack 26, and operate the control panel of the cone calorimeter to weigh the sample to be tested before the experiment. Remove the sample rack 4 containing the sample to be tested, and use the cone calorimeter 3 to perform a baseline test for 60 seconds. Then place the sample rack 4 containing the sample to be tested on the item rack 26, and adjust the height of the tray support frame of the electronic balance 27 according to the ISO5660-1 standard to control the distance from the surface of the sample to be tested to the cone calorimeter fume hood 11 to 25 mm. Turn on the thermocouple assembly 2 and the oscilloscope 1, and then start ignition for testing.

[0029] During the test, five sets of thermocouples collect flue gas temperature data from different locations in the flue gas duct and transmit it to oscilloscope 1, which stores, processes, and displays the temperature data. The temperature difference ΔT between these five sets of temperature data and room temperature is multiplied by the combustion efficiency factor η (calibrated with a standard sample such as methane before testing) to obtain the corresponding heat release rate for each thermocouple. The average value (e.g., the arithmetic mean) of these heat release rates is then calculated to obtain the real-time heat release rate, which can be used to plot a real-time heat release rate curve.

[0030] The present invention overcomes the time delay problem of traditional cone calorimeters, and the measured real-time heat release rate results are more accurate and reliable. The entire test platform is not only simple in structure and easy and quick to build, but also low in cost and easy to operate.

Claims

1. A dual heat release rate measurement platform integrating temperature difference method and oxygen consumption method, characterized by: The measurement platform includes a cone calorimeter, a sample holder, a stage, a thermocouple assembly, and a display and data processing device. The sample holder is arranged on the stage, the cone calorimeter is fixed above the sample holder, the data acquisition ends of the thermocouple assembly are distributed at different positions on the flue gas duct of the cone calorimeter, and the output end of the thermocouple assembly is connected to the display and data processing device.

2. The measuring platform according to claim 1, wherein: The thermocouple assembly includes at least two sets of thermocouple devices, one set of thermocouple devices is arranged at the center of the cone calorimeter flue gas duct, and the other thermocouple devices are arranged on the inner wall of the cone calorimeter flue gas duct.

3. The measuring platform according to claim 2, wherein: The number of the thermocouple devices is specifically 5 sets, one of which is arranged at the center of the flue gas duct of the cone calorimeter, and the remaining 4 thermocouple devices are symmetrically distributed on the inner wall of the flue gas duct of the cone calorimeter.

4. The measuring platform according to claim 1, wherein: Each thermocouple device in the thermocouple assembly includes a measuring end, an insulating tube, and a locking sleeve. The insulating tube is sleeved on the tail of the measuring end and fixed to the flue gas duct or the fixing device through the locking sleeve.

5. The measuring platform according to claim 1, wherein: The display and data processing device includes an oscilloscope, and the thermocouple assembly is connected to the oscilloscope via an oscilloscope connecting line.

6. The method for using the dual heat release rate measurement platform integrating the temperature difference method and the oxygen consumption method is characterized in that The method includes: starting a cone calorimeter for testing, allowing the flue gas generated by the combustion of the sample to be tested to flow through a flue gas duct, a thermocouple assembly collecting temperature data from different parts of the flue gas duct and transmitting the data to a display and data processing device, and the display and data processing device fitting a real-time HRR curve based on a mapping relationship formula between the measured temperature difference and HRR.

7. The method according to claim 6, wherein The formula is specifically: HRR=η*(T n -T0), where η is the combustion efficiency factor, T n is the temperature measured by the thermocouple assembly, and T0 is the room temperature.

8. The method according to claim 7, wherein: Before formal testing, standard samples must be used as raw materials for testing to verify and determine the η value in the formula.

9. The method according to claim 7, wherein: Calculate the temperature T measured by each thermocouple device in the thermocouple assembly according to the formula n The corresponding HRR values are obtained, and the average value of these HRRs is obtained and the real-time HRR curve is plotted with the temperature difference as the horizontal axis and the average value of HRR as the vertical axis.

10. The method according to claim 9, wherein: The average value includes the arithmetic mean, geometric mean, root mean square mean, harmonic mean, and weighted mean, preferably the arithmetic mean.

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