Experimental device for inhibiting thermal runaway of lithium battery by liquid nitrogen extinguishing agent

Abstract

The utility model discloses a liquid nitrogen extinguishing agent lithium battery thermal runaway inhibition experiment device, which comprises an experiment table, a first shell and a second shell, the first shell and the second shell are arranged on the experiment table, and the opening and closing of the experiment device are realized through the 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 arranged 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; according to the utility model, a single-layer structure and a double-layer structure are arranged, and through the hemispherical internal experiment cavity and the heat exchange inner groove, the flowing speed of liquid nitrogen and nitrogen is slowed down, the air distribution and uniform stress are optimized, and the cooling effect is improved.

Description

Technical Field

[0001] This utility model relates to the field of lithium battery safety testing technology, specifically to an experimental device for suppressing thermal runaway of lithium batteries using liquid nitrogen fire extinguishing agent. Background Technology

[0002] In recent years, with the popularization 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, which can easily lead to fires and explosions, causing personal injury and property damage. Therefore, research on lithium battery fire prevention and control technologies is particularly urgent and important.

[0003] Liquid nitrogen has attracted much attention as a potential fire extinguishing agent. Its boiling point at atmospheric pressure is -195.79℃, allowing it to rapidly absorb heat and evaporate into nitrogen gas. During continuous liquid nitrogen fire extinguishing, there is a brief mixing phase between the liquid nitrogen and nitrogen gas. Because nitrogen is less dense than air, it diffuses upwards. This can cause some liquid nitrogen to evaporate rapidly before making sufficient contact with the lithium battery, resulting in liquid nitrogen loss. This loss leads to a discrepancy between the amount of liquid nitrogen sprayed and the actual cooling effect achieved. Furthermore, existing experimental setups are mostly square in structure, such as those in publication CN117148196A. This design easily allows liquid nitrogen and nitrogen gas to accumulate in corners and edges, hindering airflow and reducing effective contact between the liquid nitrogen / nitrogen gas and the lithium battery surface, thus affecting the accuracy of the experiment and the evaluation of the cooling effect. Existing experimental setups and methods have not considered these issues when applying liquid nitrogen to lithium battery fire prevention experiments.

[0004] Therefore, designing a safe and controllable experimental platform to simulate lithium battery thermal runaway and extinguish fires under experimental conditions closer to ideal is crucial for evaluating the effectiveness and application conditions of liquid nitrogen and its composite extinguishing agents, and for improving the ability to prevent and control lithium battery fires. Therefore, this application proposes an experimental device for suppressing lithium battery thermal runaway using liquid nitrogen extinguishing agents. Utility Model Content

[0005] The purpose of this invention is to overcome the shortcomings and deficiencies of the prior art and provide an experimental device for suppressing thermal runaway of lithium batteries using liquid nitrogen fire extinguishing agent. The device adopts an overall spherical structure design to achieve smoother airflow organization; at the same time, through the hemispherical internal experimental chamber and heat exchange groove, the upward rapid diffusion speed of nitrogen is slowed down, increasing the contact area and time between liquid nitrogen and lithium battery, so as to solve the problems mentioned in the background art.

[0006] The objective of this utility model is achieved through the following technical solution:

[0007] An experimental device for suppressing thermal runaway of lithium batteries using liquid nitrogen extinguishing agent includes an experimental platform, a first shell, and a second shell. The first and second shells are mounted on the experimental platform, and the experimental device is opened and closed by opening and closing the first and second shells. When the first and second shells are closed, they form a hemispherical internal experimental cavity. A hollow area is provided at the bottom of the experimental cavity, and a waste collection area is assembled at the bottom of the hollow area. The waste collection area is hemispherical. An adjustable extinguishing agent injection pipe is fixedly installed on the first shell, which is connected to liquid nitrogen extinguishing agent. The inner walls of the first and second shells are provided with heat exchange grooves. The heat exchange grooves are placed inside the hemispherical internal experimental cavity and are recessed inward toward the shells of the first and second shells to form an arc surface, thereby increasing the internal experimental space, providing a larger heat dissipation surface area, and slowing down the flow rate of liquid nitrogen and nitrogen gas.

[0008] Furthermore, the adjustable extinguishing agent spraying pipeline consists of a first extinguishing agent spraying pipeline and a second extinguishing agent spraying pipeline. The outer wall of the first extinguishing agent spraying pipeline is wound with a heating coil. One end of the first extinguishing agent spraying pipeline is connected to liquid nitrogen extinguishing agent, and the other end is movably connected to the second extinguishing agent spraying pipeline through a ball-and-socket connector. The included angle between the first extinguishing agent spraying pipeline and the second extinguishing agent spraying pipeline is limited by a retaining ring lock, thereby controlling the extinguishing spray angle.

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

[0010] Furthermore, the inner arc surface of the hemispherical internal experimental cavity allows liquid nitrogen and nitrogen gas to converge and concentrate in the middle of the cavity. During injection, the liquid nitrogen and nitrogen gas mix at the bottom of the hemispherical internal experimental cavity, reducing the oxygen concentration around the lithium battery. The heat exchange grooves are distributed throughout the inner arc surface of the hemispherical internal experimental cavity, forming an uneven inner arc surface. The combination of the hemispherical internal experimental cavity and the heat exchange grooves guides the flow of the mixed liquid nitrogen and nitrogen gas within the cavity. After contacting the lithium battery, the mixed liquid nitrogen and nitrogen gas diffuse in all directions, then enter the heat exchange grooves for a brief circulation before rising along the inner arc surface curve, thereby slowing down their rising speed and prolonging the residence time of the gas around the lithium battery, thus 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 and right opening structure. The first shell and the second shell are respectively fixed to the experimental table by hinges, and the first shell is further fixed to the experimental table by a fixing pin. The outer walls of the first shell and the second shell are connected by a locking clip. A vent is provided at the top intersection, and an arc-shaped opening is provided at the bottom edge as a heat dissipation port and a cable inlet.

[0012] Furthermore, the experimental apparatus is covered with an air intake hood to collect the gases generated during the experiment.

[0013] Furthermore, the second housing is slidably connected to the wall of the first housing, and the surface of the experimental stage is provided with a locking guide rail. The second housing moves along the locking guide rail to realize the 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, and the upper cavity is a flue gas collection area. Several layers of pull-out filter layers are provided at the junction of the upper cavity and the lower cavity. 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, used to filter large particulate smoke particles generated during the experiment.

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

[0017] Furthermore, the third layer in the pull-out filter layer is a greenhouse gas filter layer, used to adsorb carbon and oxygen compounds and hydrocarbons in the flue gas.

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

[0019] This utility model also provides a method for using an experimental device for suppressing thermal runaway of lithium batteries with liquid nitrogen fire extinguishing agent, including the following steps:

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

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

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

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

[0024] S5. Install the pull-out flue gas filter layer required for the experiment;

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

[0026] S7. After placing the camera, turn on the heating device;

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

[0028] S9. Record the experimental parameters;

[0029] S10. After the lithium battery has cooled to a safe temperature, start the heating coil to defrost the liquid nitrogen injection pipe and open the first and second shells to dissipate heat and exhaust gas.

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

[0031] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0032] 1. This invention forms a hemispherical internal experimental chamber by closing the first and second shells, and combines this with a hemispherical waste collection area to form a spherical overall structure. Compared to the traditional square structure, the spherical structure avoids the formation of eddies and local accumulation of gas inside the experimental device. It also achieves a more uniform force distribution, enhances the system's explosion resistance, allows this invention to meet the experimental requirements of larger capacity lithium batteries, and significantly extends the service life of the experimental chamber.

[0033] 2. This utility model features both single-layer and double-layer structures. The inner walls of both the first and second shells are equipped with heat exchange grooves, effectively slowing the upward diffusion of liquid nitrogen and nitrogen gas. This not only promotes the uniform distribution of the mixed gas flow but also increases the contact area and time between the liquid nitrogen and the lithium battery. This design creates a stable cooling environment around the lithium battery, making experimental conditions and results closer to ideal, and reducing experimental errors caused by rapid loss of liquid nitrogen and nitrogen gas.

[0034] 3. The double-layer structure of this invention features several pull-out filter layers, effectively intercepting large smoke particles and reducing damage to precision instruments used for flue gas analysis. Furthermore, depending on the specific needs of the experiment or the limitations of the exhaust gas facilities at the experimental site, flue gas filtration or adsorption materials can be flexibly configured to remove harmful and toxic gases. This not only ensures the health and safety of experimental personnel but also significantly reduces potential environmental pollution.

[0035] 4. This utility model features an adjustable extinguishing agent injection pipe, with a retaining ring locking mechanism limiting the angle between the first and second extinguishing agent injection pipes to control the extinguishing spray angle. This design meets the experimental requirements for studying the suppression effect of lithium battery thermal runaway at different extinguishing agent injection angles.

[0036] 5. This invention features a perforated area at the bottom of the experimental chamber, with a waste collection area assembled at the bottom of the perforated area. This facilitates the collection of waste after the experiment, providing convenience for further analysis of thermal runaway and the characteristics and product composition of the extinguishing agent. The collected residues can be used for biotoxicity testing, providing important data support for assessing the potential impact of combustion products and extinguishing agents on water and soil environments. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the structure of Example 1 of the experimental device for suppressing thermal runaway of lithium batteries using liquid nitrogen fire extinguishing agent proposed in this utility model;

[0038] Figure 2 This is an exploded view of the structure of Example 1 of the experimental device for suppressing thermal runaway of lithium batteries using liquid nitrogen fire extinguishing agent proposed in this utility model;

[0039] Figure 3 This is a schematic diagram showing the connection between the liquid nitrogen fire extinguishing agent and the experimental device for suppressing thermal runaway of lithium batteries proposed in this utility model.

[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 this utility model.

[0041] Figure 5 This is a schematic diagram of the adjustable extinguishing agent injection pipe of the experimental device for suppressing thermal runaway of lithium batteries using liquid nitrogen extinguishing agent proposed in this utility model.

[0042] Figure 6 This is a schematic diagram of the locking ring structure of the experimental device for suppressing thermal runaway of lithium batteries using liquid nitrogen fire extinguishing agent proposed in this utility model;

[0043] Figure 7 This is a schematic diagram of the lithium battery installation in the experimental device for suppressing thermal runaway of lithium batteries using liquid nitrogen fire extinguishing agent proposed in this utility model.

[0044] Figure 8 for Figure 7 A magnified view of a portion of the image;

[0045] Figure 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 in this utility model;

[0046] Figure 10This is a schematic diagram of the filter layer structure of Example 2 of the experimental device for suppressing thermal runaway of lithium batteries using liquid nitrogen fire extinguishing agent proposed in this utility model;

[0047] Figure 11 This is an open state diagram of Example 2 of the experimental device for suppressing lithium battery thermal runaway with liquid nitrogen fire extinguishing agent proposed in this utility model.

[0048] Figure 12 This is a cross-sectional view of Embodiment 2 of the experimental device for suppressing lithium battery thermal runaway using liquid nitrogen fire extinguishing agent proposed in this utility model;

[0049] Figure 13 This is a schematic diagram of the pull-out filter layer structure in Example 2 of the experimental device for suppressing thermal runaway of lithium batteries using liquid nitrogen fire extinguishing agent proposed in this utility model.

[0050] In the picture:

[0051]

[0052] Detailed Implementation

[0053] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the implementation of the present invention is not limited thereto.

[0054] Please see Figure 1-13 This embodiment provides a technical solution:

[0055] Example 1:

[0056] An experimental device for suppressing thermal runaway of lithium batteries using liquid nitrogen fire extinguishing agent includes an experimental platform 1, a first housing 21, and a second housing 22. The first housing 21 and the second housing 22 are mounted on the experimental platform 1. The experimental device is opened and closed by opening and closing the first housing 21 and the second housing 22. When the first housing 21 and the second housing 22 are closed, they form a hemispherical internal experimental cavity. A hollow area 11 is provided at the bottom of the experimental cavity, and a waste collection area 12, which is also hemispherical, is assembled at the bottom of the hollow area 11. The first housing is fixedly equipped with four adjustable fire extinguishing agent spray nozzles. The first housing 21 is fixedly equipped with four adjustable extinguishing agent injection pipes 3, which are connected to liquid nitrogen extinguishing agent 4. The liquid nitrogen extinguishing agent can be used in conjunction with other extinguishing agents, including but not limited to water, perfluorohexanone, inert gas, dry powder, etc. The inner walls of the first housing 21 and the second housing 22 are provided with heat exchange grooves 23. The heat exchange grooves 23 are placed in the hemispherical internal experimental chamber and are recessed inward toward the shells of the first housing 21 and the second housing 22 to form an arc surface, thereby increasing the internal experimental space, further providing a larger heat dissipation surface area, and slowing down the flow rate of liquid nitrogen and nitrogen gas.

[0057] This embodiment uses a closed first shell 21 and second shell 22 to form a hemispherical internal experimental cavity, which, combined with a waste collection area, constitutes a spherical overall structure. Compared to the traditional square structure, the spherical structure effectively reduces thermal stress caused by temperature gradients, provides smoother airflow organization and more uniform stress distribution, not only preventing the formation of eddies and local accumulation of gas inside the experimental device, but also significantly improving the system's explosion resistance and service life. Secondly, this embodiment features both single-layer and double-layer structures. The inner walls of the first shell 21 and second shell 22 are provided with heat exchange grooves 23. The uneven inner surface slows down the upward diffusion rate of liquid nitrogen and nitrogen gas, promoting uniform distribution of the mixed airflow and increasing the contact area and time between liquid nitrogen and the lithium battery 5. This creates a stable cooling environment around the lithium battery, making the experimental conditions and results closer to the ideal state and reducing experimental errors caused by rapid loss of liquid nitrogen and nitrogen gas. Furthermore, this embodiment features an adjustable extinguishing agent injection pipe 3. A retaining ring 34 limits the angle between the first extinguishing agent injection pipe 31 and the second extinguishing agent injection pipe 32, thereby controlling the extinguishing agent injection angle and meeting the experimental requirements for studying the suppression effect of lithium battery thermal runaway at different extinguishing agent injection angles. Finally, since current experimental devices primarily focus on the collection and analysis of toxic and harmful gases, their capacity for collecting and treating solid waste and waste liquid generated during experiments is insufficient. This not only causes inconvenience for equipment maintenance but also hinders subsequent ecotoxicity testing. Therefore, this embodiment includes a hollow area 11 at the bottom of the experimental chamber. A waste collection area 12 is assembled at the bottom of the hollow area 11 to facilitate waste collection after the experiment, providing convenience for further analysis of thermal runaway and the characteristics and product composition of the extinguishing agent. The collected waste can be used for biotoxicity testing, providing important data support for assessing the potential impact of combustion and extinguishing products on water and soil environments.

[0058] The adjustable extinguishing agent spray pipe 3 in this embodiment differs from the prior art in that the spray angle of the spray pipe is adjustable, such as... Figure 5As shown, the adjustable extinguishing agent spray pipe 3 consists of a first extinguishing agent spray pipe 31 and a second extinguishing agent spray pipe 32. A heating coil 33 is wound around the outer wall of the first extinguishing agent spray pipe 31, with one end connected to liquid nitrogen extinguishing agent 4 and the other end movably connected to the second extinguishing agent spray pipe 32 via a ball-and-socket connector. A retaining ring 34 limits the included angle between the first extinguishing agent spray pipe 31 and the second extinguishing agent spray pipe 32, thereby controlling the extinguishing spray angle. In a fire extinguishing scenario of thermal runaway of the lithium battery 5, the extinguishing agent spray pipe is a key component of the fire extinguishing system. The design of the spray pipe is crucial for fire extinguishing efficiency and safety. Existing extinguishing spray pipes typically have fixed spray angles and directions, making it difficult to study the suppression effect of different extinguishing agent spray angles on lithium battery thermal runaway. Therefore, this embodiment uses an adjustable extinguishing agent spray pipe 3, whose extinguishing spray angle can be fixedly set to 0°, 30°, 45°, 60°, and 90° (e.g., ...). Figure 5 (Displayed from top to bottom) The purpose is to study the cooling and extinguishing effects of different extinguishing agents' spray angles on lithium battery runaway. This not only simulates diverse scenarios in actual applications but also provides experimental basis for optimizing extinguishing strategies and determining the optimal extinguishing spray angle. In addition, the outer wall of the first extinguishing agent spray pipe 31 is wrapped with a heating coil 33 to quickly thaw any potentially frozen agent spray pipes after the experiment and to prevent personnel from being frostbitten by liquid nitrogen during the opening and closing of liquid nitrogen valves, ensuring that personnel and experimental equipment can safely and quickly return to the ready state for the next experimental group.

[0059] In this embodiment, the angle adjustment of the adjustable extinguishing agent injection pipe 3 is achieved by the retaining ring lock 34, such as Figure 6As shown, the retaining ring 34 is further divided into a first ring 35 and a second ring 36. The first ring 35 is welded to the first extinguishing agent spray pipe 31, and the second ring 36 is welded to the second extinguishing agent spray pipe 32. The first ring 35 and the second ring 36 are respectively provided with fixing holes, and are fixed to different fixing holes by screws to form extinguishing spray angles of 0°, 30°, 45°, 60° and 90°. It should be noted that when the extinguishing spray angle is 90 degrees, a square gasket 37 is provided between the first ring 35 and the second ring 36 to reinforce the connection between the first ring 35 and the second ring 36. In addition, the first extinguishing agent injection pipe 31 welded by the first ring 35 is a universal nozzle, and the second extinguishing agent injection pipe 32 welded by the second ring 36 is a delivery pipe for liquid nitrogen extinguishing agent 4. The first ring 35 and the second ring 36 are arc-shaped. The first ring 35 is a U-shaped groove, and the second ring 36 is fixed in the groove of the first ring 35. Five fixing holes are opened in sequence on both of them, and the gap between adjacent fixing holes is equal. The included angle between the first extinguishing agent injection pipe 31 and the second extinguishing agent injection pipe 32 is limited by the snap ring lock 34, which can quickly fix the extinguishing spray angle required for the experiment. This embodiment takes 0°, 30°, 45°, 60° and 90° as examples, but includes but is not limited to the above angles.

[0060] In this embodiment, the inner arc surface of the hemispherical internal experimental cavity allows liquid nitrogen and nitrogen gas to converge and concentrate in the middle of the cavity. During injection, the liquid nitrogen and nitrogen gas mix at the bottom of the hemispherical internal experimental cavity, reducing the oxygen concentration around the lithium battery 5. The heat exchange grooves 23 are distributed throughout 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 grooves 23 work together to guide the mixed liquid nitrogen and nitrogen gas to flow within the cavity. After contacting the lithium battery, the mixed liquid nitrogen and nitrogen gas diffuse in all directions, then enter the heat exchange grooves 23 for a brief circulation before rising along the inner arc surface curve, thereby slowing down their rising speed and prolonging the residence time of the gas around the lithium battery 5, forming a concentrated and stable cooling area around the lithium battery. Specifically, when liquid nitrogen is injected in this embodiment, the liquid nitrogen and nitrogen gas are propelled towards the surface of the lithium battery by the high-speed airflow. After the gas is injected onto the surface of the lithium battery, it will diffuse in all directions and rise rapidly according to natural laws. However, the presence of the heat exchange groove structure alters this natural diffusion pattern. The heat exchange groove guides liquid nitrogen and nitrogen gas to rise in an orderly, curved motion along its surface, rather than diffusing vertically upwards in a disordered manner. This guiding effect slows down the gas's upward velocity and prolongs its residence time around the lithium battery, resulting in a more concentrated and stable cooling area around the bottom of the lithium battery. In addition, since the lithium battery 5 in the experiment is placed at the bottom of the hemispherical internal experimental cavity and heated until thermal runaway, controlling the brief mixing process of liquid nitrogen and nitrogen gas at the bottom of the cavity is beneficial to the cooling effect. Unlike existing experimental devices, the hemispherical internal experimental cavity concentrates the airflow, avoiding the problem of heat accumulation at the corners and edges of the cavity, which is conducive to heat transfer and heat dissipation. With the help of the heat exchange groove 23, the problem of poor airflow inside the cavity is avoided. At the same time, due to the hemispherical shell design, the internal pressure generated by the thermal runaway of the lithium battery 5 in this embodiment is evenly distributed, preventing structural damage caused by uneven pressure distribution and improving the structural stability and durability of the experimental device.

[0061] Existing experimental devices are mostly square in structure, such as those disclosed in CN117148196A. The square design easily leads to heat accumulation and poor airflow at corners and edges, hindering heat transfer and dissipation, thus affecting the cooling effect of liquid nitrogen. Furthermore, during lithium battery thermal runaway, the square structure is prone to structural damage due to uneven pressure distribution, resulting in poor explosion resistance. Based on the above-mentioned existing technical problems, two experimental device structures, Embodiment 1 and Embodiment 2, are proposed, specifically as follows:

[0062] This embodiment 1 is a single-layer spherical structure, such as Figures 1-3As 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. A vent 25 is provided at the top intersection, and an arc-shaped opening 24 is provided at the bottom edge as a heat dissipation vent and a cable inlet. Figure 4 As shown, the experimental apparatus is externally covered by an air intake hood 13 for collecting the gases generated during the experiment. In this embodiment, the overall structure of the experimental shell is spherical, dividing the experimental platform 1 into two parts: a hemispherical experimental cavity above the platform and a waste collection area 12 below. The platform surface between the two is made of wire mesh, allowing waste residue or liquid generated during the experiment to fall from the wire mesh into the waste collection area 12. The bottom of the waste collection area 12 has an opening, secured at both ends by hinges and latches. After opening, the waste residue or liquid is collected, and then biotoxicity testing is conducted to analyze the environmental pollution level of the products resulting from the action of the fire extinguishing agent. In this embodiment, the first shell 21 is equipped with four fire extinguishing agent injection pipe 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 combined with other fire extinguishing agents (including but not limited to water, perfluorohexanone, inert gases, dry powder, etc.) on the thermal runaway of the lithium battery 5. When the fire extinguishing agent injection pipe inlets are not in use, they are sealed with plugs. In addition, the fixing pin 213 is used to prevent the second housing 22 from exploding when the high-capacity lithium battery 5 experiences thermal runaway and generates large gas pressure, thus maintaining the stability of the injection pipe and the housing. The arc-shaped opening 24 at the bottom of the first housing 21 and the second housing 22 serves as the wiring inlet for the heating element 51 and the K-type thermocouple. The explosion vent 25 at the top is connected to the top of the housing by a hinge and a stainless steel chain, which is used to prevent the explosion vent 25 from falling off due to vibration or impact.

[0063] Example 2:

[0064] This embodiment 2 features a double-layer gourd-shaped structure, differing from embodiment 1. Embodiment 2 further improves the opening mechanism of the first shell 21 and the second shell 22, as well as the flue gas filtration and emission. The specific structure of embodiment 2 is further described below, such as... Figures 9-12 As shown:

[0065] In Embodiment 2, the first housing 21 and the second housing 22 are slidably connected. Specifically, the second housing 22 is slidably connected to the wall of the first housing 21. A locking guide rail 210 is provided on the surface of the experimental platform 1. The second housing 22 slides along the locking guide rail 210 to open and close the experimental device. In Embodiment 2, the second housing 22 is equivalent to a door slidably connected to the first housing 21. When the housing is open, it is secured by a fixing pin 213 on the experimental platform 1. This ensures that the second housing 22 will not explode when high voltage is generated due to thermal runaway of the large-capacity lithium battery 5, maintaining the stability of the injection pipe and the housing. The outer wall of the second housing 22 in Embodiment 2 is provided with a handle 212 and an observation window 211. The explosion vent 25 in Embodiment 2 is located in the first housing 21 and is connected to the outer wall of the first housing 21 by a hinge and a stainless steel chain.

[0066] In this embodiment 2, a filter layer is provided in the middle connecting 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 flue gas 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. A flue gas exhaust pipe 29 is connected to the top of the upper cavity 26. As those skilled in the art know, a series of harmful gases, including CO, HF, HCl, SO2, and CO2, are released during the thermal runaway of a lithium battery 5. These toxic and harmful gases not only pose a threat to human health but may also corrode and damage experimental equipment. If experiments are conducted in an environment without exhaust gas treatment facilities, it will not only increase the risk to personnel safety but may also pollute the environment. In addition, if the experiment involves the analysis of flue gas components, the flue gas must be guided to a gas chromatograph-mass spectrometer or other gas analysis instruments for detection. However, these precision instruments are extremely sensitive to large particulate matter in the flue gas. These particles may block the sampling port or reduce the accuracy of the analysis, thereby causing experimental errors. To further enhance the safety and environmental friendliness of the experimental apparatus, Embodiment 2 incorporates a filter layer in the central connecting area of ​​the double-layer structure. This filter layer effectively intercepts large smoke particles. Furthermore, depending on the specific experimental requirements or the limitations of the exhaust gas treatment facilities at the experimental site, the filter layer can be flexibly configured with smoke filtration or adsorption materials to remove harmful and toxic gases. This filter layer not only ensures the health and safety of experimental personnel and reduces damage to precision instruments but also significantly reduces potential environmental pollution. Simultaneously, the device considers the diversity of different experimental locations and purposes, providing high adaptability and flexibility. In addition, the upper cavity 26 of Embodiment 2 serves as a safety buffer, distributing the pressure generated by the experiment. The top exhaust pipe 29 is externally connected to a suction device to ensure complete exhaust of the smoke.

[0067] Specifically, the first filter layer structure is as follows: the first layer of the pull-out filter layer 28 is a HEPA or ULPA filter layer, used to filter large particulate smoke particles generated during the experiment; since the gas is at the nanometer level and the filter layer is at the micrometer level, the first filter layer is used to isolate some large particulate smoke particles, so as to prevent large particulate matter from clogging the sampling port of the instrument or affecting the analysis accuracy when the smoke is introduced into the precision instrument such as gas chromatograph-mass spectrometer for component analysis.

[0068] The second filter layer structure is as follows: the second layer of the pull-out filter layer 28 is an HF gas filter layer, used to filter HF generated during the experiment; since HF gas is corrosive and toxic, removing HF gas is crucial for protecting experimental equipment and personnel safety. The adsorbent for the second filter layer includes, but is not limited to, sodium fluoride, activated alumina, calcium oxide, etc., and needs to be selected according to the specific needs of the experiment.

[0069] The third filter layer structure is as follows: the third layer of the pull-out filter layer 28 is a greenhouse gas filter layer, used to adsorb carbon, oxygen, hydrocarbons, etc.; the third filter layer is activated carbon, used to adsorb carbon, oxygen, hydrocarbons, and collect greenhouse gases for subsequent processing or third-party processing, suitable for scenarios without exhaust gas treatment devices or where analysis of flue gas components is not required. Conversely, for laboratories already equipped with exhaust gas treatment devices, or for situations where exhaust gas needs to be introduced into a flue gas analyzer before being discharged into the exhaust gas treatment device, the third layer does not have an activated carbon filter layer. Furthermore, the flue gas filter layer in this embodiment is not limited to the above configuration and can be configured or adjusted according to actual experimental needs.

[0070] To further improve practicality, the first housing 21 or the second housing 22 is provided with a circular observation window 211; the circular observation window 211 in embodiment 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.

[0071] Based on the above technical solution, this embodiment also provides a method for using an experimental device for suppressing thermal runaway of lithium batteries with liquid nitrogen fire extinguishing agent, including the following steps:

[0072] S1. On the outside of the experimental platform 1, use aluminum foil tape to attach and fix the type k thermocouple to the monitoring point corresponding to the lithium battery 5.

[0073] S2. Install a heating element 51 on one side of the lithium battery 5, then add heat insulation cotton 52 on both sides, and use steel plate 53 to clamp and fix the lithium battery 5 as a whole.

[0074] S3. Open the experimental chamber, place the lithium battery 5 in the center of the wire mesh, and lead the wiring to the inlet at the bottom of the experimental device.

[0075] S4. Adjust the retaining ring 34 of the adjustable extinguishing agent injection pipe 3 to set the extinguishing injection angle that meets the experimental requirements;

[0076] S5. Install the pull-out flue gas filter layer 21 required for the experiment;

[0077] S6. Close the first shell 21 and the second shell 22 to form a hemispherical internal experimental cavity;

[0078] S7. After placing the camera, turn on the heating device;

[0079] S8. When lithium battery 5 experiences thermal runaway, immediately shut down the heating device and spray liquid nitrogen and other extinguishing agents for a predetermined time or in a predetermined dose.

[0080] S9. Record the experimental parameters;

[0081] S10. After the lithium battery 5 has cooled to a safe temperature, start the heating coil 33 to defrost the first liquid nitrogen injection pipe 31 and open the first and second shells to dissipate heat and exhaust gas.

[0082] S11. Open the latch at the bottom of the waste collection area 12 to collect the waste residue or waste liquid generated during the experiment.

[0083] The above are preferred embodiments of the present utility model, but the embodiments of the present utility model are not limited to the above content. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present utility model shall be considered equivalent substitutions and shall be included within the protection scope of the present utility model.

Claims

1. An experimental apparatus for suppressing thermal runaway of lithium batteries using liquid nitrogen fire extinguishing agent, comprising an experimental platform, characterized in that, The device also includes a first shell and a second shell, which are mounted on an experimental platform. The experimental device is opened and closed by opening and closing the first shell and the second shell. When the first shell and the second shell are closed, they form a hemispherical internal experimental cavity. The bottom of the experimental cavity is provided with a hollow area, and a waste collection area is assembled at the bottom of the hollow area. The waste collection area is hemispherical. An adjustable fire extinguishing agent injection pipe is fixedly installed on the first shell, which is connected to liquid nitrogen fire extinguishing agent. The inner walls of the first shell and the second shell are provided with heat exchange grooves. The heat exchange grooves are placed inside the hemispherical internal experimental cavity and are recessed inward toward the shells of the first shell and the second shell to form an arc surface, thereby increasing the internal experimental space, providing a larger heat dissipation surface area, and slowing down the flow rate of liquid nitrogen and nitrogen gas.

2. The experimental device for suppressing lithium battery thermal runaway using liquid nitrogen fire extinguishing agent according to claim 1, characterized in that, The adjustable extinguishing agent spraying pipeline consists of a first extinguishing agent spraying pipeline and a second extinguishing agent spraying pipeline. The outer wall of the first extinguishing agent spraying pipeline is wound with a heating coil. One end of the first extinguishing agent spraying pipeline is connected to liquid nitrogen extinguishing agent, and the other end is movably connected to the second extinguishing agent spraying pipeline through a ball socket connector. The included angle between the first extinguishing agent spraying pipeline and the second extinguishing agent spraying pipeline is limited by a retaining ring lock to control the extinguishing spray angle.

3. The experimental device for suppressing lithium battery thermal runaway using liquid nitrogen fire extinguishing agent according to claim 2, characterized in that, The locking ring is divided into a first ring and a second ring. The first ring is welded to the first extinguishing agent spray pipe, and the second ring is welded to the second extinguishing agent spray pipe. The first ring and the second ring are respectively provided with fixing holes, and are fixed to different fixing holes by screws to form extinguishing spray angles of 0°, 30°, 45°, 60° and 90°.

4. The experimental device for suppressing lithium battery thermal runaway using liquid nitrogen fire extinguishing agent according to claim 1, characterized in that, The inner arc surface of the hemispherical internal experimental cavity allows liquid nitrogen and nitrogen gas to converge and concentrate in the middle of the cavity. During injection, the liquid nitrogen and nitrogen gas mix at the bottom of the hemispherical internal experimental cavity, reducing the oxygen concentration around the lithium battery. The heat exchange grooves are distributed throughout 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 grooves work together to guide the flow of the mixed liquid nitrogen and nitrogen gas in the cavity. After contacting the lithium battery, the mixed liquid nitrogen and nitrogen gas diffuse in all directions, then enter the heat exchange grooves for a brief circulation before rising along the inner arc surface curve, thereby slowing down their rising speed and prolonging the residence time of the gas around the lithium battery, so as to form a concentrated and stable cooling area around the lithium battery.

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

6. The experimental device for suppressing lithium battery thermal runaway using liquid nitrogen fire extinguishing agent according to claim 5, characterized in that, The experimental apparatus is covered by an air intake hood to collect the gases produced in the experiment.

7. The experimental device for suppressing lithium battery thermal runaway using liquid nitrogen fire extinguishing agent according to claim 4, characterized in that, The second housing is slidably connected to the wall of the first housing. The surface of the experimental stage is provided with a locking guide rail. The second housing moves along the locking guide rail to realize the opening and closing of the experimental device.

8. The experimental device for suppressing lithium battery thermal runaway using liquid nitrogen fire extinguishing agent 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, and the upper cavity is a flue gas collection area. Several layers of pull-out filter layers are provided at the junction of the upper cavity and the lower cavity. A smoke exhaust pipe is connected to the top of the upper cavity.

9. The experimental device for suppressing lithium battery thermal runaway using liquid nitrogen fire extinguishing agent according to claim 8, characterized in that, The first layer of the pull-out filter layer is a HEPA or ULPA filter layer, used to filter large particulate smoke particles generated during the experiment; the second layer of the pull-out filter layer is an HF gas filter layer, used to filter toxic HF gas generated during the experiment. The third layer in the pull-out filter layer is a greenhouse gas filter layer, used to adsorb carbon and hydrocarbon compounds in flue gas.

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