Experimental device for inhibiting thermal runaway of lithium battery by liquid nitrogen extinguishing agent and use method of experimental device

Abstract

The invention discloses a liquid nitrogen extinguishing agent lithium battery thermal runaway inhibition experiment device which comprises an experiment table and further comprises a first shell and a second shell, the first shell and the second shell are arranged on the experiment table, and opening and closing of the experiment device are achieved through opening and closing of the first shell and the second shell. When the first shell and the second shell are closed, a hemispherical internal experiment cavity is formed, a hollow area is arranged at the bottom of the experiment cavity, a waste collecting area is assembled at the bottom of the hollow area, and the waste collecting area is hemispherical; the first shell is fixedly provided with an adjustable fire extinguishing agent injection pipeline which is externally connected with a liquid nitrogen fire extinguishing agent; heat exchange inner grooves are formed in the inner walls of the first shell and the second shell, the heat exchange inner grooves are formed in the hemispherical inner experiment cavity, and the shell bodies facing the first shell and the second shell are recessed inwards to form cambered surfaces; the device is provided with a single-layer structure and a double-layer structure, and through the hemispherical inner experiment cavity and the heat exchange inner groove, the flowing speed of liquid nitrogen and nitrogen is slowed down, air distribution and uniform stress are optimized, and the cooling effect is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium battery safety detection, and in particular to an experimental device for suppressing thermal runaway of lithium batteries using a liquid nitrogen fire extinguishing agent and a method for using the device. Background Art

[0002] In recent years, with the popularity of new energy vehicles, lithium battery fire accidents have been on the rise. Lithium batteries are prone to thermal runaway when subjected to mechanical, electrical or thermal abuse. Once thermal runaway occurs, lithium batteries are prone to fire and explosion, causing casualties and property losses. Therefore, it is particularly urgent and important to carry out research on lithium battery fire prevention and control technologies.

[0003] Liquid nitrogen has attracted much attention as a potential fire extinguishing agent. The boiling point of liquid nitrogen at normal pressure is -195.79°C, and it can quickly absorb heat and evaporate into nitrogen. When the liquid nitrogen fire extinguishing agent is continuously sprayed, there will be a short stage of liquid nitrogen and nitrogen mixing. Since the density of nitrogen is lower than that of air, nitrogen will diffuse upward. This may cause some liquid nitrogen to evaporate rapidly before it fully contacts the lithium battery, resulting in the loss of liquid nitrogen. This loss leads to inconsistency between the amount of liquid nitrogen sprayed and the actual cooling effect achieved. Moreover, most of the existing experimental devices are square structures, such as publication number CN117148196A. This design makes it easy for liquid nitrogen and nitrogen to accumulate in corners and edges, resulting in poor airflow, reducing the effective contact between liquid nitrogen and nitrogen and the surface of the lithium battery, thereby affecting the accuracy of the experiment and the evaluation of the cooling effect. The existing experimental devices and methods do not take the above problems into account when using liquid nitrogen for lithium battery fire prevention and control experiments.

[0004] Therefore, designing a safe and controllable experimental platform to simulate thermal runaway of lithium batteries and implement fire extinguishing under experimental conditions closer to the ideal state is important for evaluating the effects and application conditions of liquid nitrogen and its composite fire extinguishing agents, and for improving the prevention and control capabilities of lithium battery fires. Therefore, this application proposes an experimental device for suppressing thermal runaway of lithium batteries with liquid nitrogen fire extinguishing agents and a method for using the same. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings and deficiencies of the prior art and to provide a liquid nitrogen fire extinguishing agent to inhibit thermal runaway of lithium batteries experimental device and a method of using the same. The device adopts an overall spherical structure design to achieve smoother airflow organization; at the same time, through the hemispherical internal experimental cavity and the heat exchange inner groove, the speed of rapid upward diffusion of nitrogen is slowed down, and the contact area and time between liquid nitrogen and lithium batteries are increased to solve the problems raised in the above-mentioned background technology.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] A liquid nitrogen fire extinguishing agent suppressing lithium battery thermal runaway experimental device comprises an experimental table, and also comprises a first shell and a second shell, wherein the first shell and the second shell are arranged on the experimental table, and the opening and closing of the experimental device are realized by opening and closing the first shell and the second shell, and the first shell and the second shell are closed to form a hemispherical internal experimental cavity, and a hollow area is arranged at the bottom of the experimental cavity, and a waste collection area is assembled at the bottom of the hollow area, and the waste collection area is hemispherical; an adjustable fire extinguishing agent injection pipeline is fixedly arranged on the first shell, and the liquid nitrogen fire extinguishing agent is externally connected to the first shell; the inner walls of the first shell and the second shell are provided with a heat exchange inner groove, and the heat exchange inner groove is placed in the hemispherical internal experimental cavity, and is recessed inwardly toward the shells of the first shell and the second shell to form an arc surface, so as to increase the internal experimental space, further provide a larger heat dissipation surface area, and slow down the flow speed of liquid nitrogen and nitrogen gas.

[0008] Furthermore, the adjustable fire extinguishing agent injection pipe consists of a first fire extinguishing agent injection pipe and a second fire extinguishing agent injection pipe, the outer wall of the first fire extinguishing agent injection pipe is wrapped with a heating coil, one end of which is connected to the liquid nitrogen fire extinguishing agent, and the other end is movably connected to the second fire extinguishing agent injection pipe through a ball and socket connector, and the angle between the first fire extinguishing agent injection pipe and the second fire extinguishing agent injection pipe is limited by a snap ring lock to control the fire extinguishing injection angle.

[0009] Furthermore, the snap ring lock is divided into a first ring buckle and a second ring buckle, the first ring buckle is welded to the first fire extinguishing agent injection pipe, and the second ring buckle is welded to the second fire extinguishing agent injection pipe. The first ring buckle and the second ring buckle are respectively provided with fixing holes, which are fixed to different fixing holes by screws to form fire extinguishing injection angles of 0°, 30°, 45°, 60° and 90°.

[0010] Furthermore, the inner arc surface of the hemispherical internal experimental chamber allows the liquid nitrogen and nitrogen to gather and concentrate in the middle of the chamber. During spraying, the liquid nitrogen and nitrogen are mixed at the bottom of the hemispherical internal experimental chamber, thereby reducing the oxygen concentration around the lithium battery. The heat exchange inner groove is distributed throughout the inner arc surface of the hemispherical internal experimental chamber, forming an uneven inner arc surface. The hemispherical internal experimental chamber and the heat exchange inner groove are combined to guide the mixed liquid nitrogen and nitrogen to flow in the chamber. After the mixed liquid nitrogen and nitrogen contact the lithium battery, they diffuse everywhere, then enter the heat exchange inner groove for a short circulation, and then rise along the inner arc curve, thereby slowing down their rising speed and extending the residence time of the gas around the lithium battery, thereby forming a concentrated and stable cooling area around the lithium battery.

[0011] Furthermore, the first shell and the second shell are quarter-spherical shells with a left-right opening structure. The first shell and the second shell are respectively fixed to the experimental bench by hinges, and the first shell is further fixed to the experimental bench by a fixing pin. The outer walls of the first shell and the second shell are connected by a locking clip, an explosion vent is provided at the top intersection, and an arc-shaped opening is provided at the bottom edge as a heat dissipation outlet and a wire inlet.

[0012] Furthermore, the outside of the experimental device is covered with an air intake hood for collecting the gas generated in the experiment.

[0013] Furthermore, the second shell is slidably connected to the wall of the first shell, and a positioning guide rail is provided on the surface of the experimental table. The second shell moves along the positioning guide rail to realize opening and closing of the experimental device.

[0014] Furthermore, the experimental device is divided into an upper cavity and a lower cavity, the lower cavity is a hemispherical experimental area, the upper cavity is a smoke collection area, several layers of pull-out filter layers are arranged at the junction of the upper cavity and the lower cavity, and a smoke exhaust pipe is connected to the top of the upper cavity.

[0015] Furthermore, the first layer of the pull-out filter layer is a HEPA or ULPA filter layer, which is used to filter large smoke particles generated during the experiment.

[0016] Furthermore, the second layer in the pull-out filter layer is an HF gas filter layer, which is used to filter the poisonous gas HF generated during the experiment.

[0017] Furthermore, the third layer in the pull-out filter layer is a greenhouse gas filter layer for adsorbing carbon oxygen and hydrocarbons in flue gas.

[0018] As a preferred solution, the first shell or the second shell is provided with a circular observation window.

[0019] The present invention also provides a method for using a liquid nitrogen fire extinguishing agent to suppress thermal runaway of a lithium battery experimental device, comprising the following steps:

[0020] S1. On the outside of the experimental table, use aluminum foil tape to stick and fix the K-type thermocouple to the corresponding monitoring point of the lithium battery;

[0021] S2. Install a heating plate on one side of the lithium battery, then install heat insulation cotton on both sides, and use a steel plate to clamp and fix the lithium battery as a whole;

[0022] S3. Open the experimental box, place the lithium battery in the center of the wire mesh, and lead the wiring to the two inlets at the bottom of the experimental device;

[0023] S4. Adjust the clamping ring lock of the adjustable fire extinguishing agent injection pipe to set the fire extinguishing injection angle that meets the experimental requirements;

[0024] S5. Install the pull-out smoke filter required for the experiment;

[0025] S6, closing the first shell and the second shell to form a hemispherical internal experimental cavity;

[0026] S7, after placing the camera, start the heating device;

[0027] S8. When a lithium battery experiences thermal runaway, immediately shut down the heating device and spray liquid nitrogen or other fire extinguishing agents for a predetermined time or a predetermined dose;

[0028] S9, record experimental parameters;

[0029] S10, after the lithium battery is cooled to a safe temperature, the heating coil is started to defrost the liquid nitrogen injection pipeline, and the first and second shells are opened for heat dissipation and exhaust;

[0030] S11. Open the lock at the bottom of the waste collection area to collect the waste residue or waste liquid generated by the experiment.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1. The present invention forms a hemispherical internal experimental chamber by arranging the first shell and the second shell to be closed, and forms a spherical overall structure in combination with the hemispherical waste collection area. Compared with the traditional square structure, the spherical structure avoids the phenomenon of gas forming eddies and local aggregation inside the experimental device. It also achieves a more uniform force distribution, enhances the explosion resistance of the system, enables the present invention to meet the experimental needs of larger capacity lithium batteries, and significantly prolongs the service life of the experimental cabin.

[0033] 2. The present invention is provided with single-layer and double-layer structures, wherein the inner walls of the first shell and the second shell are provided with heat exchange inner grooves, which effectively slow down the speed of liquid nitrogen and nitrogen gas diffusion upward, which can not only promote the uniform distribution of the mixed airflow, but also help to increase the contact area and time between liquid nitrogen and lithium batteries. This design can form a steady-state cooling environment around the lithium battery, making the experimental conditions and experimental results closer to the ideal state, and reducing the experimental error caused by the rapid loss of liquid nitrogen and nitrogen gas.

[0034] 3. The double-layer structure of the present invention is provided with several layers of pull-out filter layers, which effectively intercepts large smoke particles and reduces damage to the precision instruments of smoke analysis. At the same time, according to the specific needs of the experiment or the limitations of the exhaust facilities in the experimental site, smoke filtration or adsorption materials can be flexibly configured to remove harmful and toxic gases. This not only ensures the health and safety of the experimenters, but also significantly reduces the potential pollution to the environment.

[0035] 4. The present invention is provided with an adjustable fire extinguishing agent injection pipe, and the angle between the first fire extinguishing agent injection pipe and the second fire extinguishing agent injection pipe is limited by a snap ring lock to control the fire extinguishing injection angle. This design meets the experimental requirements for studying the thermal runaway inhibition effect of lithium batteries at different fire extinguishing agent injection angles.

[0036] 5. The present invention provides a hollow area at the bottom of the experimental chamber, and a waste collection area is assembled at the bottom of the hollow area, which is convenient for collecting waste after the experiment, and provides convenience for further analysis of the characteristics and product components of thermal runaway and fire extinguishing agents. The collected residues can be used for biological toxicity testing, providing important data support for evaluating the potential impact of combustion products and fire extinguishing agents on water and soil environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a schematic structural diagram of Example 1 of an experimental device for suppressing thermal runaway of lithium batteries using a liquid nitrogen fire extinguishing agent as proposed by the present invention;

[0038] Figure 2 This is a structural explosion diagram of Example 1 of the experimental device for suppressing thermal runaway of lithium batteries using liquid nitrogen fire extinguishing agent proposed by the present invention;

[0039] Figure 3 It is a schematic diagram of the connection between the liquid nitrogen fire extinguishing agent proposed in the present invention and the experimental device for suppressing thermal runaway of lithium batteries;

[0040] Figure 4 This is a schematic diagram of the overall structure of Example 1 of the experimental device for suppressing thermal runaway of lithium batteries using liquid nitrogen fire extinguishing agent proposed in the present invention;

[0041] Figure 5 This is a schematic diagram of the structure of the adjustable fire extinguishing agent injection pipeline of the liquid nitrogen fire extinguishing agent suppression lithium battery thermal runaway experimental device proposed by the present invention;

[0042] Figure 6 It is a structural schematic diagram of the clamping ring lock of the experimental device for suppressing thermal runaway of lithium batteries with liquid nitrogen fire extinguishing agent proposed by the present invention;

[0043] Figure 7 A schematic diagram of lithium battery installation in the experimental device for suppressing thermal runaway of lithium batteries using liquid nitrogen fire extinguishing agent proposed by the present invention;

[0044] Figure 8 for Figure 7 A partial enlarged view of

[0045] Fig. 9 This is a schematic diagram of the overall structure of Example 2 of the experimental device for suppressing thermal runaway of lithium batteries using liquid nitrogen fire extinguishing agent proposed by the present invention;

[0046] Fig.10This is a schematic diagram of the filter layer structure of Example 2 of the experimental device for suppressing thermal runaway of lithium batteries with liquid nitrogen fire extinguishing agent proposed by the present invention;

[0047] Fig.11 This is an opening state diagram of Example 2 of the experimental device for suppressing thermal runaway of lithium batteries with liquid nitrogen fire extinguishing agent proposed by the present invention;

[0048] Fig.12 This is a cross-sectional view of Example 2 of the experimental device for suppressing thermal runaway of lithium batteries using liquid nitrogen fire extinguishing agent proposed by the present invention;

[0049] Fig.13 This is a schematic diagram of the pull-out filter layer structure of Example 2 of the experimental device for suppressing thermal runaway of lithium batteries with liquid nitrogen fire extinguishing agent proposed by the present invention;

[0050] In the figure:

[0051] mark name mark name 1 Test bench 11 Hollow area 12 Waste collection area 13 Suction hood 2 case 21 First shell 22 Second shell 23 Heat exchange inner groove 24 Arc opening 25 Explosion vent 26 Upper cavity 27 Lower cavity 28 Pull-out filter layer 29 Exhaust pipe 210 Card guide rail 211 Observation window 212 handle 213 Fixed pin 3 Adjustable fire extinguishing agent injection pipe 31 First fire extinguishing agent injection pipeline 32 Second fire extinguishing agent injection pipeline 33 Heating coil 34 Snap ring lock 35 First buckle 36 Second buckle 37 Square gasket 4 Liquid nitrogen fire extinguisher 5 Lithium battery 51 Heating sheet 52 Insulation cotton 53 Steel Plate 54 K-type thermocouple wire DETAILED DESCRIPTION

[0052] The present invention is further described in detail below in conjunction with embodiments and drawings, but the embodiments of the present invention are not limited thereto.

[0053] See also Figure 1-13 , this embodiment provides a technical solution:

[0054] Embodiment 1:

[0055] A liquid nitrogen fire extinguishing agent inhibits thermal runaway of a lithium battery experimental device, comprising an experimental table 1, and also comprising a first shell 21 and a second shell 22, wherein the first shell 21 and the second shell 22 are arranged on the experimental table 1, and the opening and closing of the experimental device are realized by opening and closing the first shell 21 and the second shell 22, and the first shell 21 and the second shell 22 form a hemispherical internal experimental cavity when the first shell 21 and the second shell 22 are closed, and a hollow area 11 is arranged at the bottom of the experimental cavity, and a waste collection area 12 is assembled at the bottom of the hollow area 11, and the waste collection area 12 is hemispherical; the first shell is fixedly provided with 4 adjustable fire extinguishing agent sprays The first shell 21 is fixed with four adjustable fire extinguishing agent injection pipes 3, which are externally connected to liquid nitrogen fire extinguishing agent 4. Liquid nitrogen fire extinguishing agent can be used together with other fire extinguishing agents. Other fire extinguishing agents include but are not limited to water, perfluorohexanone, inert gas, dry powder, etc.; the inner walls of the first shell 21 and the second shell 22 are provided with a heat exchange inner groove 23, and the heat exchange inner groove 23 is placed in the hemispherical internal experimental cavity, and is recessed inwardly toward the shells of the first shell 21 and the second shell 22 to form an arc surface, so as to increase the internal experimental space, further provide a larger heat dissipation surface area, and slow down the flow rate of liquid nitrogen and nitrogen gas;

[0056] In this embodiment, the first shell 21 and the second shell 22 are closed to form a hemispherical internal experimental cavity, and the waste collection area is combined to form a spherical overall structure. Compared with the traditional square structure, the spherical structure can effectively reduce the thermal stress caused by the temperature gradient, provide a smoother airflow organization and a more uniform force distribution, not only prevent the gas from forming eddies and local aggregation inside the experimental device, but also significantly improve the explosion resistance and service life of the system. Secondly, this embodiment is provided with a single-layer and double-layer structure, wherein the inner wall of the first shell 21 and the second shell 22 is provided with a heat exchange inner groove 23, and the uneven inner surface can slow down the speed of liquid nitrogen and nitrogen gas diffusion upward, which not only promotes the uniform distribution of the mixed airflow, but also helps to increase the contact area and time of liquid nitrogen and lithium battery 5, thereby forming a steady-state cooling environment around the lithium battery, making the experimental conditions and experimental results closer to the ideal state, and reducing the experimental errors caused by the rapid loss of liquid nitrogen and nitrogen gas. Again, this embodiment is provided with an adjustable fire extinguishing agent injection pipe 3, and the angle between the first fire extinguishing agent injection pipe 31 and the second fire extinguishing agent injection pipe 32 is limited by the snap ring lock 34 to control the fire extinguishing injection angle, so as to meet the experimental requirements for studying the thermal runaway inhibition effect of lithium batteries at different fire extinguishing agent injection angles. Finally, since the current experimental devices focus more on the collection and analysis of toxic and harmful gases, and the collection and treatment capacity of solid waste residues and waste liquids generated during the experiment is insufficient, which not only brings inconvenience to equipment maintenance, but also is not conducive to subsequent ecological toxicity testing, so this embodiment is provided with a hollow area 11 at the bottom of the experimental chamber, and a waste collection area 12 is assembled at the bottom of the hollow area 11, which is convenient for the collection of waste after the experiment, and provides convenience for further analysis of thermal runaway and the characteristics and product components of fire extinguishing agents. The collected waste can be used for biological toxicity testing, which provides important data support for evaluating the potential impact of combustion products and fire extinguishing products on water and soil environments.

[0057] The adjustable fire extinguishing agent injection pipeline 3 in this embodiment is different from the prior art. The injection angle of the injection pipeline is adjustable, such as Figure 5As shown, the adjustable fire extinguishing agent injection pipeline 3 is composed of a first fire extinguishing agent injection pipeline 31 and a second fire extinguishing agent injection pipeline 32. The outer wall of the first fire extinguishing agent injection pipeline 31 is wound with a heating coil 33, one end of which is connected to the liquid nitrogen fire extinguishing agent 4, and the other end is movably connected to the second fire extinguishing agent injection pipeline 32 through a ball and socket connector. The angle between the first fire extinguishing agent injection pipeline 31 and the second fire extinguishing agent injection pipeline 32 is limited by a snap ring lock 34 to control the fire extinguishing injection angle; in the fire extinguishing scenario of thermal runaway of the lithium battery 5, the fire extinguishing agent injection pipeline is a key component in the fire extinguishing system, and the design of the injection pipeline is crucial to the fire extinguishing efficiency and safety. The fire extinguishing agent injection pipeline in the prior art usually has a fixed injection angle and direction, and it is difficult to carry out research on the inhibitory effect of different fire extinguishing agent injection angles on the thermal runaway of the lithium battery. To this end, this embodiment sets an adjustable fire extinguishing agent injection pipeline 3, and its fire extinguishing injection angle can be fixedly set to 0°, 30°, 45°, 60° and 90° (such as Figure 5 The purpose is to study the cooling and fire-fighting effects of different fire-extinguishing agent injection angles on the runaway lithium battery, which can not only simulate the diverse scenarios in actual applications, but also provide an experimental basis for the optimization of fire-fighting strategies and obtain the optimal fire-fighting injection angle; in addition, a heating coil 33 is wound around the outer wall of the first fire-extinguishing agent injection pipeline 31 to quickly thaw the agent injection pipeline that may be frozen after the experiment, and to avoid frostbite of personnel by liquid nitrogen during the process of opening and closing the liquid nitrogen valve, etc., to ensure that personnel and experimental equipment can safely and quickly recover to the preparation state of the next experimental group.

[0058] In this embodiment, the angle adjustment of the adjustable fire extinguishing agent injection pipe 3 is achieved by a snap ring lock 34. Figure 6As shown, further, the snap ring lock buckle 34 is divided into a first buckle 35 and a second buckle 36, the first buckle 35 is welded to the first fire extinguishing agent injection pipe 31, and the second buckle 36 is welded to the second fire extinguishing agent injection pipe 32, and the first buckle 35 and the second buckle 36 are respectively provided with fixing holes, which are fixed to different fixing holes by screws to form fire extinguishing injection angles of 0°, 30°, 45°, 60° and 90°; it should be noted that when the fire extinguishing injection angle is 90 degrees, a square gasket 37 is arranged between the first buckle 35 and the second buckle 36 to reinforce the connection between the first buckle 35 and the second buckle 36. In addition, the first fire extinguishing agent injection pipe 31 welded by the first ring buckle 35 is a universal nozzle, and the second fire extinguishing agent injection pipe 32 welded by the second ring buckle 36 is a delivery nozzle of the liquid nitrogen fire extinguishing agent 4. The first ring buckle 35 and the second ring buckle 36 are arc-shaped, the first ring buckle 35 is a U-shaped groove part, and the second ring buckle 36 is fixed in the groove of the first ring buckle 35. The two are respectively provided with five fixing holes in sequence, and the gaps between adjacent fixing holes are equal; the angle between the first fire extinguishing agent injection pipe 31 and the second fire extinguishing agent injection pipe 32 is limited by the snap ring lock buckle 34, so that the fire extinguishing injection angle required for the experiment can be quickly fixed. This embodiment takes 0°, 30°, 45°, 60° and 90° as examples, but includes but is not limited to the above angles.

[0059] In this embodiment, the inner arc surface of the hemispherical internal experimental cavity makes the liquid nitrogen and nitrogen gather and concentrate in the middle of the cavity. When spraying, the liquid nitrogen and nitrogen are mixed at the bottom of the hemispherical internal experimental cavity, reducing the oxygen concentration around the lithium battery 5; the heat exchange inner groove 23 is spread over the inner arc surface of the hemispherical internal experimental cavity, forming an uneven inner arc surface. The hemispherical internal experimental cavity and the heat exchange inner groove 23 are combined to guide the mixed liquid nitrogen and nitrogen to flow in the cavity. After the mixed liquid nitrogen and nitrogen contact the lithium battery, they diffuse everywhere, and then enter the heat exchange inner groove 23 for a short circulation and rise along the inner arc curve, thereby slowing down their rising speed, prolonging the residence time of the gas around the lithium battery 5, and forming a concentrated and stable cooling area around the lithium battery; wherein, when the liquid nitrogen is sprayed in this embodiment, the liquid nitrogen and nitrogen are sprayed to the surface of the lithium battery under the impetus of the high-speed airflow. When the gas is sprayed to the surface of the lithium battery, it will diffuse in all directions and rise rapidly according to the law of nature. However, the presence of the heat exchange inner groove structure changes this natural diffusion mode. The heat exchange inner groove guides the liquid nitrogen and nitrogen gas to move in an orderly curved upward motion along its surface, rather than a disordered vertical upward diffusion. This guiding effect slows down the rising speed of the gas, prolongs the residence time of the gas around the lithium battery, and forms a more concentrated and stable cooling area around the lithium battery at the bottom; in addition, since the lithium battery 5 in the experiment is placed at the bottom of the hemispherical internal experimental cavity for heating until thermal runaway, controlling the short mixing process of liquid nitrogen and nitrogen gas at the bottom of the cavity is beneficial to the cooling effect. Different from the existing experimental devices, the hemispherical internal experimental cavity gathers and concentrates the airflow, avoiding the problem of heat accumulation at the corners and edges of the cavity, which is beneficial to heat transfer and heat dissipation; with the action of the heat exchange inner groove 23, the problem of poor airflow inside the cavity is avoided; at the same time, due to the hemispherical shell setting, the hemispherical internal experimental cavity of this embodiment makes the internal pressure generated by the thermal runaway of the lithium battery 5 evenly distributed, preventing structural damage caused by uneven pressure distribution, and improving the structural stability and durability of the experimental device.

[0060] Most of the existing experimental devices are square structures, such as publication number CN117148196A. The design of the square structure easily causes heat accumulation and poor airflow at the corners and edges, which is not conducive to heat transfer and heat dissipation, thereby affecting the cooling effect of liquid nitrogen. In addition, when the lithium battery is thermally runaway, the square structure is prone to structural damage due to uneven pressure distribution, and the explosion resistance is poor. Based on the above-mentioned existing technical problems, two experimental device structures, Example 1 and Example 2, are proposed, specifically:

[0061] This embodiment 1 is a single-layer spherical structure, such as Figure 1-Figure 3As shown, specifically: the first shell 21 and the second shell 22 are quarter-spherical shells with a left-right opening structure, the first shell 21 and the second shell 22 are respectively fixed to the experimental table 1 by hinges, and the first shell 21 is further fixed to the experimental table by a fixing pin 213, the outer walls of the first shell 21 and the second shell 22 are connected by a locking clip, an explosion vent 25 is provided at the top intersection, and an arc-shaped opening 24 is provided at the bottom edge as a heat dissipation port and a line inlet; as shown Figure 4 As shown, the outside of the experimental device is covered with an air hood 13 for collecting the gas generated by the experiment; the overall structure of the experimental shell of this embodiment 1 is spherical, dividing the experimental table 1 into two parts, the upper part of the experimental table 1 is a hemispherical experimental cavity, and the lower part of the experimental table 1 is a waste collection area 12. The experimental table surface between the two is set as a wire mesh, so that the waste residue or waste liquid generated during the experiment falls from the wire mesh to the waste collection area 12. The bottom of the waste collection area 12 is provided with an opening, and the two ends of the opening are fixed by hinges and locks. After opening, the waste residue or waste liquid after the experiment is collected, and then biological toxicity detection is carried out to analyze the degree of pollution to the environment by the products after the fire extinguishing agent acts. The first shell 21 of this embodiment 1 is provided with four fire extinguishing agent injection pipeline inlets, which can be used to analyze the inhibitory effect of liquid nitrogen alone on the thermal runaway of the lithium battery 5 or the inhibitory effect of liquid nitrogen and other fire extinguishing agents (including but not limited to water, perfluorohexanone, inert gas, dry powder, etc.) on the thermal runaway of the lithium battery 5. When the fire extinguishing agent injection pipeline inlet is not used, it is blocked with a plug. In addition, the fixing pin 213 is used to limit the second shell 22 from being blown open when the large-capacity lithium battery 5 generates a large air pressure due to thermal runaway, so as to maintain the stability of the injection pipe and the box. The arc-shaped opening 24 at the bottom of the first shell 21 and the second shell 22 is used for the line inlet of the heating plate 51 and the K-shaped thermocouple. The top explosion vent 25 is connected to the top of the box by a hinge and a stainless steel chain, and the stainless steel chain is used to prevent the explosion vent 25 from falling off due to vibration or impact.

[0062] Embodiment 2:

[0063] The second embodiment is a double-layer gourd-shaped structure. Different from the first embodiment, the second embodiment has further improved the opening method of the first shell 21 and the second shell 22, as well as the smoke filtering and emission. The specific structure of the second embodiment is further described below. Figure 9-12 As shown:

[0064] The first shell 21 and the second shell 22 in Example 2 are slidably connected, specifically: the second shell 22 is slidably connected to the wall of the first shell 21, and the surface of the experimental table 1 is provided with a positioning guide rail 210, and the second shell 22 slides along the positioning guide rail 210 to realize the opening and closing of the experimental device; the second shell 22 of Example 2 is equivalent to a door slidably connected to the first shell 21, and the shell is opened along the positioning guide rail 210. When in the closed state, the second shell 22 is fixed by a fixed latch 213 on the experimental table 1 to ensure that when the large-capacity lithium battery 5 thermally runs away and generates high pressure, the second shell 22 will not be blown open, and the stability of the injection pipe and the box body is maintained. The outer wall of the second shell 22 of Example 2 is provided with a handle 212 and an observation window 211. The explosion vent 25 of Example 2 is provided in the first shell 21, and is connected to the outer wall of the first shell 21 by a hinge and a stainless steel chain.

[0065] In this embodiment 2, a filter layer is provided in the middle connection area of ​​the double-layer structure. The experimental device is divided into an upper cavity 26 and a lower cavity 27. The lower cavity 27 is a hemispherical experimental area, and the upper cavity 26 is a smoke collection area. Several layers of pull-out filter layers 28 are provided at the connection between the upper cavity 26 and the lower cavity 27, and a smoke exhaust pipe 29 is connected to the top of the upper cavity 26. It is well known to those skilled in the art that a series of harmful gases, including CO, HF, HCl, SO2, CO2, etc., will be released during the thermal runaway of the lithium battery 5. The above-mentioned toxic and harmful gases will not only pose a threat to human health, but may also cause corrosion and damage to the experimental equipment. If the experiment is carried out in an environment without exhaust gas treatment facilities, it will not only increase the life safety of the personnel, but also may cause pollution to the environment. In addition, if the experiment involves the analysis of the smoke components, the smoke must be guided to a gas phase mass spectrometer or other gas analysis instrument for detection. However, these precision instruments are extremely sensitive to large particles in the smoke, which may block the sampling port or reduce the accuracy of the analysis, thereby causing experimental errors. To this end, in Example 2, in order to further improve the safety and environmental protection of the experimental device, a filter layer is set in the middle connection area of ​​the double-layer structure, which can effectively intercept large smoke particles, and flexibly configure smoke filtration or adsorption materials according to the specific needs of the experiment or the limitations of the exhaust treatment facilities of the experimental site to remove harmful and toxic gases. The filter layer not only ensures the health and safety of the experimenters and reduces damage to precision instruments, but also significantly reduces the potential pollution to the environment. At the same time, the device also takes into account the diversity of different experimental sites and purposes, and provides a high degree of adaptability and flexibility. In addition, the upper cavity 26 of Example 2 serves as a safety buffer zone to share the pressure generated by the experiment, and the top exhaust pipe 29 is externally connected to a suction device to ensure that the smoke is completely discharged.

[0066] Among them, the structure of the first filter layer is specifically as follows: the first layer in the pull-out filter layer 28 is a HEPA or ULPA filter layer, which is used to filter large smoke particles generated during the experiment; since the gas is at the nanometer level and the filter layer is at the micron level, the first filter layer is used to isolate some large smoke particles to avoid introducing smoke into precision instruments such as gas mass spectrometers to analyze components, where large particles block the sampling port of the instrument or affect the analysis accuracy.

[0067] The second filter layer structure is as follows: the second layer in the pull-out filter layer 28 is an HF gas filter layer, which is used to filter the HF generated during the experiment; since HF gas is corrosive and toxic, removing HF gas is essential for protecting the safety of experimental equipment and personnel. The adsorbent of the second filter layer includes but is not limited to sodium fluoride, activated alumina, calcium oxide, etc., which needs to be selected according to the specific needs of the experiment.

[0068] The structure of the third filter layer is specifically as follows: the third layer in the pull-out filter layer 28 is a greenhouse gas filter layer, which is used to adsorb carbon oxygen, hydrocarbons, etc.; the third filter layer is activated carbon, which is used to adsorb carbon oxygen, hydrocarbons, collect greenhouse gases, and facilitate subsequent processing or third-party processing. It is suitable for scenarios where there is no exhaust gas treatment device or no analysis of flue gas components is required. On the contrary, for laboratories equipped with exhaust gas treatment devices, or where exhaust gas needs to be introduced into a flue gas analyzer and then discharged into an exhaust gas treatment device, the third layer does not have an activated carbon filter layer. In addition, the flue gas filter layer of this embodiment is not limited to the above settings, and can also be set or adjusted according to actual experimental needs.

[0069] To further improve practicality, the first shell 21 or the second shell 22 is provided with a circular observation window 211; the circular observation window 211 in Example 1 or 2 is made of transparent explosion-proof high-strength glass, which can be used for real-time observation and recording of the internal experimental process using a camera.

[0070] On the basis of the above technical solution, this embodiment also provides a method for using a liquid nitrogen fire extinguishing agent to suppress thermal runaway of a lithium battery experimental device, comprising the following steps:

[0071] S1. On the outside of the experimental table 1, use aluminum foil tape to stick and fix the K-type thermocouple to the monitoring point corresponding to the lithium battery 5;

[0072] S2, installing a heating plate 51 on one side of the lithium battery 5, then installing heat insulation cotton 52 on both sides, and using a steel plate 53 to clamp and fix the lithium battery 5 as a whole;

[0073] S3, open the experimental box, place the lithium battery 5 at the center of the wire mesh, and lead the wiring to the wire inlet at the bottom of the experimental device;

[0074] S4, adjusting the clamping ring lock 34 of the adjustable fire extinguishing agent injection pipe 3 to set the fire extinguishing injection angle that meets the experimental requirements;

[0075] S5. Install the pull-out smoke filter layer 21 required for the experiment;

[0076] S6, closing the first shell 21 and the second shell 22 to form a hemispherical internal experimental chamber;

[0077] S7, after placing the camera, start the heating device;

[0078] S8. When the lithium battery 5 experiences thermal runaway, the heating device is immediately turned off and liquid nitrogen or other fire extinguishing agents are sprayed for a predetermined time or a predetermined dosage;

[0079] S9, record experimental parameters;

[0080] S10, after the lithium battery 5 is cooled to a safe temperature, the heating coil 33 is started to defrost the first liquid nitrogen injection pipe 31, and the first and second shells are opened for heat dissipation and exhaust;

[0081] S11, open the lock at the bottom of the waste collection area 12 to collect waste residues or waste liquid generated by the experiment.

[0082] The above is a preferred embodiment of the present invention, but the embodiment of the present invention is not limited to the above content. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A liquid nitrogen composite fire extinguishing agent to inhibit thermal runaway of lithium batteries experimental device, including a test bench, characterized in that: The experimental device also includes a first shell and a second shell, which are arranged on a test bench, and the opening and closing of the experimental device are realized by opening and closing the first shell and the second shell. When the first shell and the second shell are closed, a hemispherical internal experimental cavity is formed, and a hollow area is arranged at the bottom of the experimental cavity, and a waste collection area is assembled at the bottom of the hollow area, and the waste collection area is hemispherical; the first shell is fixedly provided with an adjustable fire extinguishing agent injection pipeline, which is externally connected to a liquid nitrogen fire extinguishing agent; the inner walls of the first shell and the second shell are provided with a heat exchange inner groove, and the heat exchange inner groove is placed in the hemispherical internal experimental cavity, and is recessed inwardly toward the shells of the first shell and the second shell to form an arc surface, so as to increase the internal experimental space, further provide a larger heat dissipation surface area, and slow down the flow rate of liquid nitrogen and nitrogen gas.

2. According to claim 1, a liquid nitrogen composite fire extinguishing agent to inhibit thermal runaway of lithium batteries experimental device, characterized in that: The adjustable fire extinguishing agent injection pipeline consists of a first fire extinguishing agent injection pipeline and a second fire extinguishing agent injection pipeline. The outer wall of the first fire extinguishing agent injection pipeline is wrapped with a heating coil, one end of which is connected to the liquid nitrogen fire extinguishing agent, and the other end is movably connected to the second fire extinguishing agent injection pipeline through a ball and socket connector. The angle between the first fire extinguishing agent injection pipeline and the second fire extinguishing agent injection pipeline is limited by a snap ring lock to control the fire extinguishing injection angle.

3. The liquid nitrogen composite fire extinguishing agent to inhibit thermal runaway of lithium batteries experimental device according to claim 2 is characterized in that: The snap ring lock buckle is divided into a first buckle and a second buckle, the first buckle is welded to the first fire extinguishing agent injection pipe, and the second buckle is welded to the second fire extinguishing agent injection pipe. The first buckle and the second buckle are respectively provided with fixing holes, which are fixed to different fixing holes by screws to form fire extinguishing injection angles of 0°, 30°, 45°, 60° and 90°.

4. The liquid nitrogen composite fire extinguishing agent to inhibit thermal runaway of lithium batteries experimental device according to claim 1 is characterized in that: The inner arc surface of the hemispherical internal experimental chamber allows the liquid nitrogen and nitrogen to gather and concentrate in the middle of the chamber. When spraying, the liquid nitrogen and nitrogen are mixed at the bottom of the hemispherical internal experimental chamber, reducing the oxygen concentration around the lithium battery; the heat exchange inner groove is distributed on the inner arc surface of the hemispherical internal experimental chamber to form an uneven inner arc surface. The hemispherical internal experimental chamber and the heat exchange inner groove are combined to guide the mixed liquid nitrogen and nitrogen to flow in the chamber. After the mixed liquid nitrogen and nitrogen contact the lithium battery, they diffuse everywhere, then enter the heat exchange inner groove for a short circulation, and then rise along the inner arc curve, thereby slowing down its rising speed and extending the residence time of the gas around the lithium battery, so that a concentrated and stable cooling area is formed around the lithium battery.

5. The liquid nitrogen composite fire extinguishing agent to inhibit thermal runaway of lithium batteries experimental device according to claim 4 is characterized in that: The first shell and the second shell are quarter-spherical shells with a left-right opening structure. The first shell and the second shell are respectively fixed to the experimental bench by hinges, and the first shell is further fixed to the experimental bench by a fixing pin. The outer walls of the first shell and the second shell are connected by a locking clip, an explosion vent is provided at the top intersection, and an arc-shaped opening is provided at the bottom edge as a heat dissipation vent and a line inlet.

6. The liquid nitrogen composite fire extinguishing agent to inhibit thermal runaway of lithium batteries experimental device according to claim 5, characterized in that: The outside of the experimental device is covered with an air suction hood for collecting the gas generated in the experiment.

7. The liquid nitrogen composite fire extinguishing agent to inhibit thermal runaway of lithium batteries experimental device according to claim 4 is characterized in that: The second shell is slidably connected to the wall of the first shell, and a locking guide rail is arranged on the surface of the experimental table. The second shell moves along the locking guide rail to realize the opening and closing of the experimental device.

8. The liquid nitrogen composite fire extinguishing agent to inhibit thermal runaway of lithium batteries experimental device according to claim 7, characterized in that: The experimental device is divided into an upper cavity and a lower cavity, the lower cavity is a hemispherical experimental area, the upper cavity is a smoke collection area, a plurality of pull-out filter layers are arranged at the junction of the upper cavity and the lower cavity, and a smoke exhaust pipe is connected to the top of the upper cavity.

9. The liquid nitrogen composite fire extinguishing agent to inhibit thermal runaway of lithium batteries experimental device according to claim 8, characterized in that: The first layer of the pull-out filter layer is a HEPA or ULPA filter layer, which is used to filter large smoke particles generated during the experiment; the second layer of the pull-out filter layer is an HF gas filter layer, which is used to filter the toxic gas HF generated during the experiment; The third layer in the pull-out filter layer is a greenhouse gas filter layer, which is used to absorb carbon, oxygen and hydrocarbons in the flue gas.

10. A method for using the experimental device according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1. On the outside of the experimental table, use aluminum foil tape to stick and fix the K-type thermocouple to the corresponding monitoring point of the lithium battery; S2. Install a heating plate on one side of the lithium battery, then install heat insulation cotton on both sides, and use a steel plate to clamp and fix the lithium battery as a whole; S3. Open the experimental box, place the lithium battery in the center of the wire mesh, and lead the wiring to the two inlets at the bottom of the experimental device; S4. Adjust the clamping ring lock of the adjustable fire extinguishing agent injection pipe to set the fire extinguishing injection angle that meets the experimental requirements; S5. Install the pull-out smoke filter required for the experiment; S6, closing the first shell and the second shell to form a hemispherical internal experimental cavity; S7, after placing the camera, start the heating device; S8. When a lithium battery experiences thermal runaway, immediately shut down the heating device and spray liquid nitrogen or other fire extinguishing agents for a predetermined time or a predetermined dose; S9, record experimental parameters; S10, after the lithium battery is cooled to a safe temperature, the heating coil is started to defrost the liquid nitrogen injection pipeline, and the first and second shells are opened for heat dissipation and exhaust; S11. Open the lock at the bottom of the waste collection area to collect the waste residue or waste liquid generated by the experiment.

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