Experimental device and method for researching water immersion fire extinguishing efficiency of lithium battery of charging cabinet of electric bicycle

Abstract

The invention relates to an experimental device and method for researching the water immersion fire extinguishing efficiency of a lithium battery of a charging cabinet, and the device comprises a thermal runaway system which is used for simulating a thermal runaway scene of the lithium battery of the charging cabinet; the water circulation system is used for realizing water immersion and water circulation fire extinguishing functions; and the data acquisition system is used for acquiring experiment data such as images, temperature and gas concentration in the experiment process. The method comprises the following steps: when only a charging cabinet lithium battery thermal runaway experiment is carried out, assembling a lithium battery pack, selecting a thermal runaway triggering mode according to working conditions to trigger thermal runaway of the lithium battery pack, recording experimental data, adjusting experimental parameters, and repeating the experiment; when a charging cabinet lithium battery water immersion fire extinguishing experiment is completely carried out, a lithium battery pack is assembled, a thermal runaway triggering mode is selected according to working conditions to trigger thermal runaway of the lithium battery pack, a water immersion system is started, experiment data are recorded, experiment parameters are adjusted, and then the experiment is repeated.

Description

Technical Field

[0001] The present invention relates to the technical field of fire protection of lithium batteries in charging cabinets, and in particular to an experimental device and method for studying the fire extinguishing efficiency of lithium batteries in charging cabinets by water immersion. Background Art

[0002] In the context of "dual carbon", with people's growing requirements for battery life and safe charging, charging cabinets as centralized charging facilities for electric bicycles have developed rapidly in recent years. According to the "White Paper on the Development of China's Electric Two-Wheeled Vehicle Battery Swapping Industry (2021)" released by the China Battery Research Institute, with the development of the market and policy promotion, it is expected that the market demand for battery swap cabinets will increase by more than 10 times in 2025, reaching 670,000. However, while charging cabinets provide convenience to people, they also bring safety hazards. In many recent charging cabinet fire accidents, the aerosol fire extinguishing devices equipped with the charging cabinets and the dry powder fire extinguishing agents in public places generally did not have a fire extinguishing effect. The fire was not brought under control until the firefighters arrived at the scene to extinguish the fire. The inadequacy of the fire protection design of the charging cabinets has seriously restricted the development of the industry.

[0003] Currently, the most common fire extinguishing technology for charging cabinets is the release of spray-type fire extinguishing agents, including fine water mist, heptafluoropropane, perfluorohexanone, carbon dioxide, and aerosols. Heptafluoropropane and perfluorohexanone have good fire extinguishing effects but are relatively expensive. Carbon dioxide, aerosols, and fine water mist can temporarily extinguish open flames but cannot prevent the battery from reigniting. Water immersion has attracted widespread attention due to its low cost, high cooling efficiency, and good anti-reignition effect. However, research on this fire extinguishing technology by domestic and foreign scholars is still limited. Water immersion fire extinguishing technology for lithium batteries in charging cabinets is still immature. Parameters such as water injection time, water injection flow rate, water immersion height, and cycle start time after thermal runaway of lithium batteries in charging cabinets need to be clarified urgently. Research on the effectiveness of water immersion fire extinguishing is of great significance for guiding the safe development of the charging cabinet industry. Summary of the Invention

[0004] The purpose of the present invention is to solve the problems in the prior art and to provide an experimental device and method for comparing the effects of different water immersion parameters on the fire extinguishing efficiency of lithium batteries in electric bicycle charging cabinets.

[0005] The technical solution adopted by the present invention to solve the technical problem is to provide an experimental device for studying the water immersion fire extinguishing efficiency of lithium batteries in electric bicycle charging cabinets, comprising:

[0006] The thermal runaway system includes a lithium battery pack, a cast copper heating plate, and a charge-discharge cycler. The lithium battery pack is placed in the experimental chamber. Depending on the experimental conditions, the cast copper heating plate or the charge-discharge cycler is connected to the lithium battery pack to create thermal runaway conditions.

[0007] The water circulation system includes a water tank, a water pump, an experimental chamber, a water pipe, and a solenoid valve; the water filling hole on the cover of the experimental chamber is connected to a water pipe, and a solenoid valve A is installed near the end of the water pipe on the cover. The other end of the water pipe is installed at the water outlet of the water pump. The water inlet of the water pump is connected to a water pipe, and the other end of the water pipe is connected to the water outlet of the water tank; the water outlet hole on the right side of the experimental chamber body is connected to a water pipe, and a solenoid valve B is installed near the end of the water pipe on the experimental chamber. The other end of the water pipe is connected to the water filling hole on the water tank cover;

[0008] The data acquisition system includes a camera, a temperature collector, and a flue gas analyzer. The camera is placed inside the experimental chamber, the temperature collector is connected to the lithium battery pack, and the flue gas analyzer air inlet is placed inside the experimental chamber.

[0009] Preferably, the lithium battery pack is fixed in the experimental chamber by a clamp to prevent the battery pack from being displaced when water is injected to extinguish the fire;

[0010] Preferably, the water pump speed can be adjusted to adjust the water injection flow rate;

[0011] Preferably, the flue gas analyzer installed in the experimental chamber can monitor typical gases of thermal runaway of lithium batteries such as CO, H2, and CH4;

[0012] Preferably, one side of the experimental chamber is explosion-proof glass, and the other sides are steel plates;

[0013] An experimental method for studying the fire extinguishing efficiency of lithium batteries in charging cabinets under water immersion includes the following steps:

[0014] ①Only conduct thermal runaway and combustion experiments on lithium battery packs in charging cabinets

[0015] S1, determine the model, type and quantity of lithium batteries, assemble the selected lithium batteries into a lithium battery pack according to the set connection method and arrangement method, if using a cast copper heating plate as the thermal runaway triggering method, then fix the cast copper heating plate and the lithium battery pack in the experimental chamber with a clamp in advance, if using a charge-discharge cycler overcharge as the thermal runaway triggering method, then fix the lithium battery pack in the experimental chamber and connect it to the charge-discharge cycler via voltage and current lines;

[0016] S2, close solenoid valve A, close solenoid valve B;

[0017] S3, start the cast copper heating plate or charge and discharge cycler to provide thermal runaway conditions for the lithium battery pack;

[0018] S4: Check the lithium battery pack for thermal runaway or combustion through the explosion-proof glass surface on the experimental chamber. At the same time, measure the temperature inside the lithium battery pack through the thermocouple in the gap between the lithium batteries. When the temperature inside the lithium battery pack reaches the temperature change range set in the experiment, turn off the cast copper heating plate or the charge-discharge cycler.

[0019] S5, record the temperature data measured by all thermocouples to determine the temperature conditions of the lithium battery pack during the experiment; use the flue gas analyzer to identify the gas components and concentrations generated by the thermal runaway of the lithium battery pack; use high-speed cameras and cameras to record the experimental details of the lithium battery pack;

[0020] S6, after the thermal runaway or combustion process of the lithium battery pack ends and the ambient temperature of the experimental chamber returns to normal temperature, clean up the residues, change the model, type, quantity, connection method, arrangement method or thermal runaway triggering method of the lithium battery according to the experimental conditions, and then repeat S1 to S5;

[0021] ②. Completely carry out the water immersion fire extinguishing test of the charging cabinet lithium battery

[0022] S1, determine the model, type and quantity of lithium batteries, assemble the selected lithium batteries into a lithium battery pack according to the set connection method and arrangement method, if using a cast copper heating plate as the thermal runaway triggering method, then fix the cast copper heating plate and the lithium battery pack in the experimental chamber with a clamp in advance, if using a charge-discharge cycler overcharge as the thermal runaway triggering method, then fix the lithium battery pack in the experimental chamber and connect it to the charge-discharge cycler via voltage and current lines;

[0023] S2, turn on the water pump to fill the solenoid valve A with water;

[0024] S3, start the cast copper heating plate or charge and discharge cycler to provide thermal runaway conditions for the lithium battery pack;

[0025] S4: Check the lithium battery pack for thermal runaway or combustion through the explosion-proof glass surface on the experimental chamber. At the same time, measure the temperature inside the lithium battery pack through the thermocouple in the gap between the lithium batteries. When the temperature inside the lithium battery pack reaches the temperature change range set in the experiment, turn off the cast copper heating plate or the charge-discharge cycler.

[0026] S5, at the specified time, open the solenoid valve A, fill water into the experimental chamber to the specified height, then close the water pump to stop water injection;

[0027] S6, at the specified time, open the solenoid valve B, start the water pump, and start water circulation to extinguish the fire of the lithium battery pack;

[0028] S7, record the temperature data measured by all thermocouples to determine the temperature conditions of the lithium battery pack during the experiment; use the flue gas analyzer to identify the gas components and concentrations generated by the thermal runaway of the lithium battery pack; use a high-speed camera and a video camera to record the experimental details of the lithium battery pack;

[0029] S8, when the temperature of the lithium battery pack is lower than the specified value, turn off the water pump to stop water injection, and wait until the ambient temperature of the experimental chamber returns to normal temperature, open the experimental chamber drain port to drain the remaining water in the experimental chamber, clean up the residue, change the experimental parameters such as water injection flow rate, water injection depth, water injection time, water circulation start time, and then repeat S1 to S7;

[0030] The complete implementation of the charging cabinet lithium battery water immersion fire extinguishing test S6 is specifically as follows: according to the experimental conditions, the water immersion fire extinguishing effect of different lithium battery packs with thermal runaway is different; if the thermal runaway of the lithium battery pack has been suppressed after the water is initially filled to the specified height, the solenoid valve B will not be opened; if the thermal runaway of the lithium battery pack is not suppressed after the water is initially filled to the specified height, the water pump and the solenoid valve B will be opened to start water circulation fire extinguishing.

[0031] Beneficial effects of the present invention:

[0032] By setting different parameters such as water injection flow rate, water injection time, water injection depth, and cycle start time, the effectiveness of water immersion fire extinguishing is studied, which can provide a basis for the actual charging cabinet water immersion fire extinguishing technology;

[0033] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 Schematic diagram of the overall device of an embodiment of the present invention;

[0035] Figure 2 A schematic diagram of a battery fixing device according to an embodiment of the present invention;

[0036] In the figure, 1 is a charge-discharge cycler, 2 is a voltage and current line, 3 is a cover plate, 4 is a water injection hole, 5 is a solenoid valve A, 6 is a water pipe, 7 is a water pump, 8 is a water tank, 9 is a cover plate, 10 is a solenoid valve B, 11 is a fixture, 12 is a sewage outlet, 13 is a cast copper heating plate, 14 is a lithium battery pack, 15 is a bracket, 16 is a camera, 17 is a temperature controller, 18 is a temperature collector, 19 is a test chamber, 20 is a flue gas analyzer, 21 is a water pipe, 22 is a water pipe, 23 is a high-speed camera, 24 is a water injection hole, 25 is a thermocouple DETAILED DESCRIPTION

[0037] See also Figures 1 to 2 As shown, the overall schematic diagram of the device of the embodiment of the present invention and the schematic diagram of the battery fixing device of the embodiment of the present invention, the water tank 8 is connected to the water injection hole 4 of the cover plate 3 on the experimental chamber 19 through the water pipe 21, the water pump 7, the water pipe 6, and the solenoid valve A5, so that the water in the water tank 8 can be injected into the experimental chamber 19;

[0038] The experimental chamber is connected to the water filling hole 24 of the water tank cover 9 through the water pipe 22 and the solenoid valve B10, so that the water in the experimental chamber 19 after filling can flow back to the water tank 8;

[0039] The lithium battery pack 14 is fixed in the experimental chamber 19 by the clamp 11, and the camera 16 and the high-speed camera 23 are arranged near the lithium battery pack 11. The camera 16 is arranged inside the experimental chamber and is responsible for recording the entire fire extinguishing experiment process. The high-speed camera 23 is arranged outside the experimental chamber 19, facing the explosion-proof glass surface of the experimental chamber. The high-speed camera captures the water injection depth and the details of the thermal runaway phenomenon of the lithium battery pack through the explosion-proof glass surface for subsequent analysis; the flue gas analyzer 20 is installed on the top of the experimental chamber 19 to monitor the type and concentration of gases generated during the thermal runaway of the lithium battery, and can reflect the fire extinguishing effect through the change of gas volume during the fire extinguishing process; the temperature collector 18 is connected to the thermocouple 25 attached to the surface of the lithium battery pack to monitor the temperature changes of the lithium battery pack during the experiment;

[0040] The cast copper heating plate 13 is fixed to the surface of the lithium battery pack 14 by the clamp 11, and is used to heat the lithium battery pack 14 to achieve thermal runaway; the charge and discharge cycler 1 is connected to the lithium battery pack 14 through the voltage and current line 2, and is used to overcharge the lithium battery pack 14 to induce thermal runaway, and monitor the voltage and current changes during the experiment.

[0041] An experimental method for studying the fire extinguishing efficiency of lithium batteries in charging cabinets by water immersion, using the experimental device for studying the fire extinguishing efficiency of lithium batteries in charging cabinets by water immersion, includes the following steps:

[0042] ①Only conduct thermal runaway and combustion experiments on lithium battery packs in charging cabinets

[0043] S1, determine the model, type and quantity of the lithium batteries, assemble the selected lithium batteries into a lithium battery pack 14 according to the set connection method and arrangement method, if the cast copper heating plate 13 is used as the thermal runaway triggering method for heating, then the cast copper heating plate 13 and the lithium battery pack 14 are fixed in advance in the experimental chamber 19 by the clamp 11, if the charge and discharge cycler 1 overcharge is used as the thermal runaway triggering method, then the lithium battery pack 14 is fixed in the experimental chamber 19 and connected to the charge and discharge cycler 1 through the voltage and current line;

[0044] S2, close solenoid valve A5, close solenoid valve B10;

[0045] S3, start the cast copper heating plate 13 or the charge-discharge cycler 1 to provide thermal runaway conditions for the lithium battery pack 14;

[0046] S4, check the lithium battery pack 14 for thermal runaway or combustion through the explosion-proof glass surface of the experimental chamber 19, and measure the temperature data inside the lithium battery pack 14 through the thermocouple 25 in the gap between the lithium batteries. When the temperature inside the lithium battery pack 14 reaches the temperature change range set in the experiment, turn off the cast copper heating plate 13 or the charge-discharge cycler 1;

[0047] S5, recording the temperature data measured by all thermocouples 25 to determine the temperature conditions of the lithium battery pack during the experiment; using the flue gas analyzer 20 to identify the gas components and concentrations generated by the thermal runaway of the lithium battery pack 14; using the high-speed camera 23 and the camera 16 to record the experimental details of the lithium battery pack 14;

[0048] S6: After the thermal runaway or combustion process of the lithium battery pack 14 ends and the ambient temperature of the experimental chamber 19 returns to normal, clean up the residue. Depending on the experimental conditions, change the lithium battery model, type, quantity, connection method, arrangement, or thermal runaway triggering method, and then repeat S1 to S5.

[0049] ②. Completely carry out the water immersion fire extinguishing test of the charging cabinet lithium battery

[0050] S1, determine the model, type and quantity of lithium batteries, assemble the selected lithium batteries into a lithium battery pack 14 according to the set connection method and arrangement method, if the cast copper heating plate 13 is used as the thermal runaway triggering method for heating, then the cast copper heating plate and the lithium battery pack 14 are fixed in the experimental chamber with a clamp in advance, if the charge-discharge cycler 1 overcharge is used as the thermal runaway triggering method, then the lithium battery pack 14 is fixed in the experimental chamber 19 and connected to the charge-discharge cycler 1 through the voltage and current line;

[0051] S2, turn on the water pump 7 to fill the solenoid valve A5 with water;

[0052] S3, starting the cast copper heating plate 13 or the charge-discharge cycler 1 to provide thermal runaway conditions for the lithium battery pack 14;

[0053] S4, check whether the lithium battery pack has thermal runaway or combustion through the explosion-proof glass on the experimental chamber 19, and at the same time measure the temperature data inside the lithium battery pack 14 through the thermocouple 25 in the gap between the lithium batteries. When the temperature inside the lithium battery pack 14 reaches the temperature change range set in the experiment, turn off the cast copper heating plate 13 or the charge-discharge cycler 1;

[0054] S5, at the specified time, open the solenoid valve A5, fill water into the experimental chamber 19 to the specified height, then close the water pump to stop water injection;

[0055] S6, at the designated time, open the solenoid valve B10, start the water pump 7, and start water circulation fire extinguishing of the lithium battery pack 14;

[0056] S7, recording the temperature data measured by all thermocouples 5 to determine the temperature of the lithium battery pack 14 during the experiment; using the flue gas analyzer 20 to identify the gas components and concentrations generated by the thermal runaway of the lithium battery pack; using the high-speed camera 23 and the camera 16 to record the experimental details of the lithium battery pack 14;

[0057] S8: When the temperature of the lithium battery pack 14 falls below the specified value, the water pump is turned off to stop water injection. After the ambient temperature of the experimental chamber 19 returns to normal, the drain port 12 is opened to drain the remaining water from the experimental chamber and clean up the residue. Experimental parameters such as water injection flow rate, water injection depth, water injection time, and water circulation start time are changed, and then S1 to S7 are repeated;

[0058] The above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the scope of protection of the present invention shall be included in the scope of protection of the present invention.

Claims

1. An experimental device for studying the fire extinguishing efficiency of lithium batteries in charging cabinets by water immersion, characterized in that: include: The thermal runaway system includes a lithium battery pack, a cast copper heating plate, and a charge-discharge cycler. The lithium battery pack is placed in the experimental chamber. Depending on the experimental conditions, the cast copper heating plate or the charge-discharge cycler is connected to the lithium battery pack to create thermal runaway conditions. The water circulation system includes a water tank, a water pump, an experimental chamber, a water pipe, and a solenoid valve; the water filling hole on the cover of the experimental chamber is connected to a water pipe, and a solenoid valve A is installed near the end of the water pipe on the cover. The other end of the water pipe is installed at the water outlet of the water pump. The water inlet of the water pump is connected to a water pipe, and the other end of the water pipe is connected to the water outlet of the water tank; the water outlet hole on the right side of the experimental chamber body is connected to a water pipe, and a solenoid valve B is installed near the end of the water pipe on the experimental chamber. The other end of the water pipe is connected to the water filling hole on the water tank cover; The data acquisition system includes a camera, a high-speed camera, a temperature collector and a flue gas analyzer; the camera is arranged inside the experimental chamber, the high-speed camera is arranged on the front of the explosion-proof glass of the experimental chamber, the temperature collector is connected to the lithium battery pack, and the air inlet of the flue gas analyzer is arranged inside the experimental chamber.

2. An experimental device for studying the fire extinguishing efficiency of lithium batteries in charging cabinets by water immersion according to claim 1, characterized in that: The lithium battery pack is fixed in the experimental chamber by a clamp to prevent the battery pack from being displaced when water is injected to extinguish the fire.

3. An experimental device for studying the fire extinguishing efficiency of lithium batteries in charging cabinets by water immersion according to claim 1, characterized in that: The solenoid valve A can control the water flow in the water pipe above the experimental chamber in advance by opening and closing the valve, and can quickly inject water when needed to ensure that the lithium battery pack is submerged in water as soon as possible.

4. An experimental device for studying the fire extinguishing efficiency of lithium batteries in charging cabinets by water immersion according to claim 1, characterized in that: The solenoid valve B can control the water circulation start time and water filling height through the opening and closing states.

5. An experimental method for studying the fire extinguishing efficiency of lithium batteries in charging cabinets under water immersion as described in any one of claims 1 to 4, characterized in that: The following steps are involved: ①Only conduct thermal runaway and combustion experiments on lithium battery packs in charging cabinets S1, determine the model, type and quantity of lithium batteries, assemble the selected lithium batteries into a lithium battery pack according to the set connection method and arrangement method, if using a cast copper heating plate as the thermal runaway triggering method, then fix the cast copper heating plate and the lithium battery pack in the experimental chamber with a clamp in advance, if using a charge-discharge cycler overcharge as the thermal runaway triggering method, then fix the lithium battery pack in the experimental chamber and connect it to the charge-discharge cycler via voltage and current lines; S2, close solenoid valve A, close solenoid valve B; S3, start the cast copper heating plate or charge and discharge cycler to provide thermal runaway conditions for the lithium battery pack; S4: Check the lithium battery pack for thermal runaway or combustion through the explosion-proof glass surface on the experimental chamber. At the same time, measure the temperature inside the lithium battery pack through the thermocouple in the gap between the lithium batteries. When the temperature inside the lithium battery pack reaches the temperature change range set in the experiment, turn off the cast copper heating plate or the charge-discharge cycler. S5, record the temperature data measured by all thermocouples to determine the temperature conditions of the lithium battery pack during the experiment; use the flue gas analyzer to identify the gas components and concentrations generated by the thermal runaway of the lithium battery pack; use high-speed cameras and cameras to record the experimental details of the lithium battery pack; S6: After the thermal runaway or combustion process of the lithium battery pack ends and the ambient temperature of the experimental chamber returns to normal, clean up the residue. According to the experimental conditions, change the parameters such as the model, type, quantity, connection method, arrangement method or thermal runaway triggering method of the lithium battery, and then repeat S1 to S5; ②. Completely carry out the water immersion fire extinguishing test of the charging cabinet lithium battery S1, determine the model, type and quantity of lithium batteries, assemble the selected lithium batteries into a lithium battery pack according to the set connection method and arrangement method, if using a cast copper heating plate as the thermal runaway triggering method, then fix the cast copper heating plate and the lithium battery pack in the experimental chamber with a clamp in advance, if using a charge-discharge cycler overcharge as the thermal runaway triggering method, then fix the lithium battery pack in the experimental chamber and connect it to the charge-discharge cycler via voltage and current lines; S2, turn on the water pump to fill the solenoid valve A with water; S3, start the cast copper heating plate or charge and discharge cycler to provide thermal runaway conditions for the lithium battery pack; S4: Check the lithium battery pack for thermal runaway or combustion through the explosion-proof glass surface on the experimental chamber. At the same time, measure the temperature inside the lithium battery pack through the thermocouple in the gap between the lithium batteries. When the temperature inside the lithium battery pack reaches the temperature change range set in the experiment, turn off the cast copper heating plate or the charge-discharge cycler. S5, at the specified time, open the solenoid valve A, fill water into the experimental chamber to the specified height, then close the water pump to stop water injection; S6, at the specified time, open the solenoid valve B, start the water pump, and start water circulation to extinguish the fire of the lithium battery pack; S7, record the temperature data measured by all thermocouples to determine the temperature conditions of the lithium battery pack during the experiment; use the flue gas analyzer to identify the gas components and concentrations generated by the thermal runaway of the lithium battery pack; use a high-speed camera and a video camera to record the experimental details of the lithium battery pack; In step S8, when the temperature of the lithium battery pack falls below the specified value, the water pump is turned off to stop water injection. After the ambient temperature of the experimental chamber returns to normal, the drain port of the experimental chamber is opened to drain the remaining water and clean up the residue. Experimental parameters such as water injection depth, water injection time, and water circulation start time are changed, and steps S1 to S7 are repeated.

6. The experimental method for studying the fire extinguishing efficiency of lithium batteries in charging cabinets by water immersion according to claim 5 is characterized in that: The complete implementation of the charging cabinet lithium battery water immersion fire extinguishing test S6 is specifically as follows: according to the experimental conditions, the water immersion fire extinguishing effect of different lithium battery packs with thermal runaway is different. If the thermal runaway of the lithium battery pack has been suppressed after the water is initially filled to the specified height, the solenoid valve B will not be opened; if the thermal runaway of the lithium battery pack is not suppressed after the water is initially filled to the specified height, the water pump and the solenoid valve B will be opened to start water circulation fire extinguishing.

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