A method and system for controlling the amount of liquid nitrogen used to extinguish a thermal runaway fire of a lithium-ion battery

Abstract

The application discloses a liquid nitrogen quantity control method and system for lithium ion battery thermal runaway fire fighting, and belongs to the technical field of fire safety. b , specific heat capacity C P of the lithium ion battery, minimum temperature T1 of the lithium ion battery when the temperature rising speed exceeds 0.02 DEG C / min, maximum temperature T2 of the battery surface when the temperature continuously rises, average temperature T C in the energy storage container, environment temperature T Z of the energy storage container and the number n of the lithium ion batteries with thermal runaway; S2, obtaining heat energy generated when a single lithium ion battery has thermal runaway fire; firstly, the thermal runaway fire of the single lithium ion battery is divided into a self-heat generation stage and a heat release stage; then, heat generated by the single lithium ion battery in the two different stages is calculated respectively; S3, obtaining heat absorption heat of the liquid nitrogen; S4, calculating the liquid nitrogen extinguishing quantity; and S5, controlling the liquid nitrogen quantity M 控 , so that M 控 is not less than M n .

Description

Technical Field

[0001] This invention belongs to the field of fire safety technology, and in particular relates to a method and system for controlling the amount of liquid nitrogen used in extinguishing thermal runaway fires of lithium-ion batteries. Background Technology

[0002] Under the "dual carbon" goal, lithium-ion batteries, due to their high energy density and long lifespan, are widely used as a substitute for fossil fuels in various fields such as electric vehicles, portable electronic products, and electrochemical energy storage. However, during large-scale application, fires and explosions caused by thermal runaway during their life cycle seriously hinder application safety. Scholars both domestically and internationally have conducted extensive research to analyze rapid response methods for lithium battery thermal runaway. Currently, C6F is the primary extinguishing agent used for lithium-ion battery thermal runaway fires. 12 O, C3HF7, CO2, and N2—the standards set by the National Fire Protection Association (NFPA) in the United States specify the minimum atmospheric concentration (MEC) of extinguishing agents. Experimental tests yielded corresponding MEC values ​​of 7%, 9%, 25–30%, and 40%, respectively. Experiments also showed that using C6F… 12 O and C3HF7 can quickly extinguish fires in lithium titanate LTO single cells, boxed batteries, and small battery packs. However, the violent chemical reactions inside the battery continue, and thermal runaway flammable gases are continuously ejected from the battery, leading to the possibility of reignition. Comparative experiments showed that CO2 and C3HF7 had relatively poor cooling and fire extinguishing effects, with flames still appearing. Experimental studies on the thermal runaway characteristics of lithium iron phosphate batteries under different SOCs in air, N2, and CO2 gas environments revealed that both CO2 and N2 have good suppression effects on the combustion and explosion of power lithium-ion batteries after prolonged exposure, with CO2 exhibiting better fire extinguishing and explosion suppression properties than N2. To address the issue that extinguishing agents such as CO2, C3HF7, and N2 cannot quickly reduce the temperature of thermally runaway batteries to a safe level, some researchers have proposed using liquid nitrogen to treat thermally runaway lithium-ion batteries. Fire extinguishing experiments on 18650 commercial batteries have shown that liquid nitrogen effectively reduces the battery surface temperature through thin-film boiling heat transfer and radiative heat transfer, delaying the onset of internal thermal runaway. This effectively prevents and controls lithium-ion battery thermal runaway fires. 18650 batteries typically have a capacity of 1800-3600mAh, classifying them as small batteries. With the development of the battery industry, the typical commercial energy storage battery currently in use is a 280Ah high-capacity battery. The most common application of 280Ah batteries is in energy storage containers, which are widely used in large-scale energy generation and consumption, distributed generation and microgrids. When using liquid nitrogen to extinguish lithium-ion battery thermal runaway fires inside energy storage containers, there is currently a lack of quantitative control methods for the minimum amount of liquid nitrogen used. That is, when using liquid nitrogen to extinguish lithium-ion battery fires, it is impossible to accurately control the amount of liquid nitrogen used, which often results in waste of liquid nitrogen. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a method for controlling the amount of liquid nitrogen used in extinguishing lithium-ion battery thermal runaway fires. The method divides the thermal runaway process of a lithium-ion battery into a heat generation stage and a combustion stage, and compares and analyzes the heat released during these stages with the latent heat of liquid nitrogen vaporization and the heat absorbed during nitrogen temperature rise. Finally, while meeting the liquid nitrogen requirements for extinguishing lithium-ion battery thermal runaway fires, the method quantitatively determines the amount of liquid nitrogen needed.

[0004] The specific technical solution adopted in this invention is as follows:

[0005] The primary objective of this patent is to provide a method for controlling the amount of liquid nitrogen used in extinguishing thermal runaway fires in lithium-ion batteries, including:

[0006] S1. Obtain basic data: Mass M of a single lithium-ion battery b Specific heat capacity C of lithium-ion batteries P The lowest temperature T1 during the stage where the lithium-ion battery's own temperature rise rate exceeds 0.02℃ / min; the highest temperature T2 during the stage where the battery surface temperature continuously rises; and the average temperature T inside the energy storage container. C Ambient temperature T of energy storage container Z The number of lithium-ion batteries that experienced thermal runaway, n;

[0007] S2. Obtain the thermal energy generated during a thermal runaway fire in a single lithium-ion battery using basic data; specifically:

[0008] First, the thermal runaway fire of a single lithium-ion battery is divided into the self-heating stage and the heat release stage.

[0009] Then, the heat generated by a single lithium-ion battery in the two different stages was calculated separately:

[0010] During its own heat generation stage: ;

[0011] In the formula: Q1 is the total heat released by a single lithium-ion battery during its own heat generation phase;

[0012] During the heat release phase: ;

[0013] In the formula: m1, m2, m3, and m4 are fitted data, t is the time after an open flame appears inside the energy storage container, and Q2 is the heat released during the thermal runaway combustion stage of a single lithium-ion battery.

[0014] S3. Obtain the endothermic heat from liquid nitrogen; specifically:

[0015] The latent heat of liquid nitrogen can be calculated using the following formula:

[0016]

[0017] In the formula: W1 is the latent heat absorbed by liquid nitrogen; C n1 The latent heat of liquid nitrogen; M n Mass of liquid nitrogen;

[0018] Calculate the heat absorbed by the temperature rise after liquid nitrogen vaporization using the following formula:

[0019]

[0020] In the formula: W2 is the heat absorbed by the liquid nitrogen upon vaporization; C n2 T is the specific heat capacity of nitrogen. n1 T represents the average temperature inside the energy storage container after liquid nitrogen vaporization. n2 This is the initial temperature after liquid nitrogen vaporization;

[0021] S4. Calculate the amount of liquid nitrogen needed for fire extinguishing; specifically:

[0022] Establish the energy conservation formula:

[0023]

[0024] In the formula: n is the number of lithium-ion batteries that have experienced thermal runaway; The heat loss coefficient is the coefficient of heat absorption.

[0025] Calculate the mass of liquid nitrogen using the energy conservation formula:

[0026] ;

[0027] S5, Control the liquid nitrogen volume M 控 This makes M 控 Not less than M n .

[0028] Preferably, m1, m2, m3, and m4 are each 2.5 × 10⁻⁶. 7 3.1×10 5 2060.7, 144.99.

[0029] Preferably, .

[0030] Preferably, T1 and T2 are obtained using EV-ARC testing.

[0031] A second objective of this invention is to provide a liquid nitrogen volume control system for extinguishing lithium-ion battery thermal runaway fires, comprising:

[0032] Basic data acquisition module: Acquires basic data: Mass M of a single lithium-ion battery b Specific heat capacity C of lithium-ion batteries PThe lowest temperature T1 during the stage where the lithium-ion battery's own temperature rise rate exceeds 0.02℃ / min; the highest temperature T2 during the stage where the battery surface temperature continuously rises; and the average temperature T inside the energy storage container. C Ambient temperature T of energy storage container Z The number of lithium-ion batteries that experienced thermal runaway, n;

[0033] Single Lithium-ion Battery Thermal Energy Analysis Module: This module uses basic data to obtain the thermal energy generated when a single lithium-ion battery experiences thermal runaway or fire; specifically:

[0034] First, the thermal runaway fire of a single lithium-ion battery is divided into the self-heating stage and the heat release stage.

[0035] Then, the heat generated by a single lithium-ion battery in the two different stages was calculated separately:

[0036] During its own heat generation stage: ;

[0037] In the formula: Q1 is the total heat released by a single lithium-ion battery during its own heat generation phase;

[0038] During the heat release phase: ;

[0039] In the formula: m1, m2, m3, and m4 are fitted data, t is the time after an open flame appears inside the energy storage container, and Q2 is the heat released during the thermal runaway combustion stage of a single lithium-ion battery.

[0040] Liquid nitrogen endothermic heat analysis module: This module acquires the endothermic heat of liquid nitrogen; specifically:

[0041] The latent heat of liquid nitrogen can be calculated using the following formula:

[0042]

[0043] In the formula: W1 is the latent heat absorbed by liquid nitrogen; C n1 The latent heat of liquid nitrogen; M n Mass of liquid nitrogen;

[0044] Calculate the heat absorbed by the temperature rise after liquid nitrogen vaporization using the following formula:

[0045]

[0046] In the formula: W2 is the heat absorbed by the liquid nitrogen upon vaporization; C n2 T is the specific heat capacity of nitrogen. n1 T represents the average temperature inside the energy storage container after liquid nitrogen vaporization. n2 This is the initial temperature after liquid nitrogen vaporization;

[0047] Liquid nitrogen fire extinguishing dosage calculation module: Calculates the amount of liquid nitrogen needed for fire extinguishing; specifically:

[0048] Establish the energy conservation formula:

[0049] In the formula: n is the number of lithium-ion batteries that have experienced thermal runaway; The heat loss coefficient is the coefficient of heat absorption.

[0050] Calculate the mass of liquid nitrogen using the energy conservation formula:

[0051]

[0052] Control module: controls the amount of liquid nitrogen M 控 This makes M 控 Not less than M n .

[0053] Preferably, m1, m2, m3, and m4 are each 2.5 × 10⁻⁶. 7 3.1×10 5 2060.7, 144.99.

[0054] Preferably, ;

[0055] Preferably, T1 and T2 are obtained using EV-ARC testing.

[0056] The third objective of this patent is to provide a computer program for implementing the above-mentioned liquid nitrogen quantity control method for extinguishing thermal runaway fires in lithium-ion batteries.

[0057] The fourth objective of this patent is to provide an information data processing terminal for implementing the above-mentioned liquid nitrogen quantity control method for extinguishing thermal runaway fires in lithium-ion batteries.

[0058] The fifth objective of this patent is to provide a computer-readable storage medium, including instructions that, when executed on a computer, cause the computer to perform the aforementioned liquid nitrogen quantity control method for extinguishing thermal runaway fires in lithium-ion batteries.

[0059] By adopting the above technical solution, the present invention has the following technical effects:

[0060] This invention first divides the thermal runaway process of lithium-ion batteries into a self-heating stage and a combustion stage, and quantitatively calculates the energy generated during the thermal runaway process. Then, it quantitatively calculates the heat energy absorbed by liquid nitrogen vaporization. Subsequently, it compares and analyzes the energy generated during the thermal runaway process of lithium-ion batteries with the latent heat of liquid nitrogen vaporization and the heat absorbed by nitrogen temperature rise. Finally, under the premise of meeting the liquid nitrogen requirements in the event of a lithium-ion battery thermal runaway fire, it quantitatively determines the amount of liquid nitrogen needed to extinguish the fire. Attached Figure Description

[0061] Figure 1 A flowchart of a preferred embodiment of the present invention;

[0062] Figure 2 This is a system block diagram in a preferred embodiment of the present invention;

[0063] Figure 3 This is a comparison chart of the data calculated by the fitting formula and the measured data in a preferred embodiment of the present invention. Detailed Implementation

[0064] To further understand the invention's content, features, and effects, the following embodiments are provided, and detailed descriptions are given in conjunction with the accompanying drawings.

[0065] The structure of the present invention will now be described in detail with reference to the accompanying drawings.

[0066] Please see Figure 1 A method for controlling the amount of liquid nitrogen used in extinguishing thermal runaway fires in lithium-ion batteries, comprising:

[0067] S1. Obtain basic data: Mass M of a single lithium-ion battery b Specific heat capacity C of lithium-ion batteries P The lowest temperature T1 during the stage where the lithium-ion battery's own temperature rise rate exceeds 0.02℃ / min; the highest temperature T2 during the stage where the battery surface temperature continuously rises; and the average temperature T inside the energy storage container. C Ambient temperature T of energy storage container Z The number n of lithium-ion batteries that experienced thermal runaway; where:

[0068] (1) Mass M of a single lithium-ion battery b You can find out the battery brand and model number, or you can test it on-site in advance.

[0069] (2) Specific heat capacity C of lithium-ion battery P The battery brand and model number can be found, or it can be obtained by testing under adiabatic conditions using EV+ARC experimental equipment.

[0070] (3) The lowest temperature T1 when the lithium battery’s own temperature rise rate exceeds 0.02℃ / min was obtained by testing under adiabatic conditions using EV+ARC experimental equipment.

[0071] (4) The highest temperature T2 during the stage of continuous rise of battery surface temperature was obtained by testing under adiabatic conditions using EV+ARC experimental equipment.

[0072] (5) Average temperature T inside the energy storage container C The average temperature was calculated by measuring the temperature at different heights on both sides and in the middle of the container using K-type thermocouples.

[0073] (6) Ambient temperature T of energy storage container Z The results were obtained by testing the exterior of the container using a type K thermocouple.

[0074] (7) The number of lithium-ion batteries with thermal runaway, n, is obtained by analyzing the voltage and temperature of each battery on site. When the voltage is lower than 3.2V and the temperature exceeds 50℃, it is considered that thermal runaway has occurred inside.

[0075] S2. Obtain the thermal energy generated during a thermal runaway fire in a single lithium-ion battery using basic data; specifically:

[0076] First, the thermal runaway fire of a single lithium-ion battery is divided into the self-heating stage and the heat release stage.

[0077] Then, the heat generated by a single lithium-ion battery in the two different stages was calculated separately:

[0078] During its own heat generation stage: ;

[0079] In the formula: Q1 is the total heat released by a single lithium-ion battery during its own heat generation phase, in J and M. b The mass of a single lithium-ion battery is expressed in kg; C P The unit is J / (kg·℃). T1 is the lowest temperature at which the lithium battery's own temperature rise rate exceeds 0.02℃ / min, and T2 is the highest temperature at which the SEI film on the surface of the battery's negative electrode material melts, and the reaction between the electrolyte and the negative electrode material intensifies, causing the battery surface temperature to gradually rise. C P T1 and T2 are generally obtained using EV-ARC testing.

[0080] During the heat release phase: ;

[0081] In the formula: m1, m2, m3, and m4 are the fitted data, each being 2.5 × 10⁻⁶. 7 3.1×10 5 2060.7, 144.99. t is the time after an open flame appears inside the energy storage container, in seconds. Q2 is the heat released during the thermal runaway combustion phase of the lithium-ion battery, in J.

[0082] S3. Obtain the endothermic heat from liquid nitrogen; specifically:

[0083] The latent heat of liquid nitrogen can be calculated using the following formula:

[0084]

[0085] In the formula: W1 is the latent heat absorbed by liquid nitrogen; the unit is J; C n1This refers to the latent heat of liquid nitrogen; the unit is J / kg, typically taken as 99742.86 J / kg; M n Mass of liquid nitrogen; unit: kg;

[0086] Calculate the heat absorbed by the temperature rise after liquid nitrogen vaporization using the following formula:

[0087]

[0088] In the formula: W2 is the heat absorbed by the temperature rise after liquid nitrogen vaporization; the unit is J; C n2 This refers to the specific heat capacity of nitrogen; the unit is J / (kg·℃), and a value of 1039 J / (kg·℃) is generally accepted. n1 T represents the average temperature inside the energy storage container after liquid nitrogen vaporization. n2 The initial temperature after liquid nitrogen vaporization; unit: °C.

[0089] S4. Calculate the amount of liquid nitrogen needed for fire extinguishing; specifically:

[0090] Establish the energy conservation formula:

[0091]

[0092] In the formula: n is the number of lithium-ion batteries that have experienced thermal runaway; The heat loss coefficient is the coefficient for heat absorption.

[0093] Calculate the mass of liquid nitrogen using the energy conservation formula:

[0094] ;

[0095] In the formula: The heat loss coefficient is related to the average temperature inside the energy storage container and the ambient temperature outside the container. The larger the temperature difference, the lower the coefficient. It is generally taken as 0.2~0.7. The calculation formula is as follows:

[0096] ;

[0097] Among them, T C T represents the average temperature inside the energy storage container. Z The external ambient temperature of the energy storage container;

[0098] S5, Control the liquid nitrogen volume M 控 This makes M 控 Not less than M n .

[0099] Please see Figure 2 A liquid nitrogen volume control system for extinguishing lithium-ion battery thermal runaway fires, comprising:

[0100] Basic data acquisition module: Acquires basic data: Mass M of a single lithium-ion battery b Specific heat capacity C of lithium-ion batteries P The lowest temperature T1 during the stage where the lithium-ion battery's own temperature rise rate exceeds 0.02℃ / min; the highest temperature T2 during the stage where the battery surface temperature continuously rises; and the average temperature T inside the energy storage container. C Ambient temperature T of energy storage container Z The number n of lithium-ion batteries that experienced thermal runaway; where:

[0101] (1) Mass M of a single lithium-ion battery b You can find out the battery brand and model number, or you can test it on-site in advance.

[0102] (2) Specific heat capacity C of lithium-ion battery P The battery brand and model number can be found, or it can be obtained by testing under adiabatic conditions using EV+ARC experimental equipment.

[0103] (3) The lowest temperature T1 when the lithium battery’s own temperature rise rate exceeds 0.02℃ / min was obtained by testing under adiabatic conditions using EV+ARC experimental equipment.

[0104] (4) The highest temperature T2 during the stage of continuous rise of battery surface temperature was obtained by testing under adiabatic conditions using EV+ARC experimental equipment.

[0105] (5) Average temperature T inside the energy storage container C The average temperature was calculated by measuring the temperature at different heights on both sides and in the middle of the container using K-type thermocouples.

[0106] (6) Ambient temperature T of energy storage container Z The results were obtained by testing the exterior of the container using a type K thermocouple.

[0107] (7) The number of lithium-ion batteries with thermal runaway, n, is obtained by analyzing the voltage and temperature of each battery on site. When the voltage is lower than 3.2V and the temperature exceeds 50℃, it is considered that thermal runaway has occurred inside.

[0108] Single Lithium-ion Battery Thermal Energy Analysis Module: This module uses basic data to obtain the thermal energy generated when a single lithium-ion battery experiences thermal runaway or fire; specifically:

[0109] First, the thermal runaway fire of a single lithium-ion battery is divided into the self-heating stage and the heat release stage.

[0110] Then, the heat generated by a single lithium-ion battery in the two different stages was calculated separately:

[0111] During its own heat generation stage: ;

[0112] In the formula: Q1 is the total heat released by a single lithium-ion battery during its own heat generation phase, in J and M. b The mass of a single lithium-ion battery is expressed in kg; C P The unit is J / (kg·℃). T1 is the lowest temperature at which the lithium battery's own temperature rise rate exceeds 0.02℃ / min, and T2 is the highest temperature at which the SEI film on the surface of the battery's negative electrode material melts, and the reaction between the electrolyte and the negative electrode material intensifies, causing the battery surface temperature to gradually rise. C P T1 and T2 are generally obtained using EV-ARC testing;

[0113] During the heat release phase: ;

[0114] In the formula: m1, m2, m3, and m4 are the fitted data, each being 2.5 × 10⁻⁶. 7 3.1×10 5 2060.7, 144.99. t is the time after an open flame appears inside the energy storage container, in seconds. Q2 is the heat released during the thermal runaway combustion phase of the lithium-ion battery, in J.

[0115] Liquid nitrogen endothermic heat analysis module: This module acquires the endothermic heat of liquid nitrogen; specifically:

[0116] The latent heat of liquid nitrogen can be calculated using the following formula:

[0117]

[0118] In the formula: W1 is the latent heat absorbed by liquid nitrogen; the unit is J; C n1 This refers to the latent heat of liquid nitrogen; the unit is J / kg, typically taken as 99742.86 J / kg; M n Mass of liquid nitrogen; unit: kg;

[0119] Calculate the heat absorbed by the temperature rise after liquid nitrogen vaporization using the following formula:

[0120]

[0121] In the formula: W2 is the heat absorbed by the temperature rise after liquid nitrogen vaporization; the unit is J; C n2 This refers to the specific heat capacity of nitrogen; the unit is J / (kg·℃), and a value of 1039 J / (kg·℃) is generally accepted. n1 T represents the average temperature inside the energy storage container after liquid nitrogen vaporization. n2 The initial temperature after liquid nitrogen vaporization; unit: °C.

[0122] Liquid nitrogen fire extinguishing dosage calculation module: Calculates the amount of liquid nitrogen needed for fire extinguishing; specifically:

[0123] Establish the energy conservation formula:

[0124]

[0125] In the formula: n is the number of lithium-ion batteries that have experienced thermal runaway; The heat loss coefficient is the coefficient of heat absorption.

[0126] Calculate the mass of liquid nitrogen using the energy conservation formula:

[0127] ;

[0128] In the formula: The heat loss coefficient is related to the average temperature inside the energy storage container and the ambient temperature outside the container. The larger the temperature difference, the lower the coefficient. It is generally taken as 0.2~0.7. The calculation formula is as follows:

[0129] ;

[0130] Among them, T C T represents the average temperature inside the energy storage container. Z The external ambient temperature of the energy storage container;

[0131] Control module: controls the amount of liquid nitrogen M 控 This makes M 控 Not less than M n .

[0132] Case 1: Verification formula for a full-scale lithium-ion battery experimental platform:

[0133] ;

[0134] To verify the effectiveness of the above formula, a full-scale lithium-ion battery experimental platform was built. This platform was used to test the total heat release during combustion of a 280 Ah lithium iron phosphate battery at 100% SOC. Before the experiment, the lithium iron phosphate battery was charged to 100% SOC using a 7.1kW cycle charger. During the experiment, a 14cm×16cm, 500W heating element was used to heat the 280Ah lithium iron phosphate battery, triggering its thermal runaway. After the thermal runaway generated gas, an electric ignition device was used to ignite the runaway gas. Based on the oxygen consumption principle, a heat release rate experimental device was used to collect the change in oxygen in the combustion flue gas. The change in the total heat released during combustion during battery thermal runaway was tested, and the comparison between the data calculated by the fitted formula and the measured data is shown below. Figure 3 As shown, the maximum error rate is concentrated between 1250s and 1850s, with a maximum error rate of 15%. This can be mitigated by adjusting the heat loss coefficient during liquid nitrogen extinguishing. Error correction; experimental results as follows Figure 3 As shown.

[0135] Case Study 2: Verifying Formulas by Building a Full-Size Energy Storage Container Experimental Platform:

[0136] ;

[0137] The EV-ARC battery thermal runaway experimental setup was used to test the self-heating and heat release under adiabatic thermal runaway conditions of a 280Ah battery. The test revealed that at 70.62℃ (T1), the battery's self-generated heat generation rate exceeded 0.02℃ / min, indicating that it had entered the self-heating stage. As the SEI film on the surface of the battery's negative electrode material melted, the reaction between the electrolyte and the negative electrode material intensified, causing the battery surface temperature to gradually rise, reaching 200.65℃ (T2). The 280Ah battery has a mass of 5.435kg and a specific heat capacity C... p The average temperature inside the lithium iron phosphate battery energy storage container after liquid nitrogen vaporization is 1029.5 J / (kg·℃). n1 The initial temperature (T) after liquid nitrogen vaporization is 25℃. n2 The latent heat of vaporization of liquid nitrogen is -198℃. n1 The value is 99742.86 J / kg, and the specific heat capacity of nitrogen (C) is... n2 The value was taken as 1039 J / (kg·℃). The highest ambient temperature during the experiment reached 30℃, therefore the heat loss coefficient (J / (kg·℃)) was... The value is set to 0.2. Substituting the above data into the formula, the minimum amount of liquid nitrogen used for fire extinguishing (M) can be calculated. n The weight is 21.48 kg.

[0138] To verify the effectiveness of the minimum liquid nitrogen extinguishing calculation formula, a full-size energy storage container experimental platform was constructed. The container dimensions were 5830mm × 2340mm × 2600mm, and it mainly included battery modules, a thermal runaway triggering device, a pressure relief port, multi-parameter data acquisition equipment, and a liquid nitrogen extinguishing and explosion suppression device. Before the experiment, a 280Ah lithium iron phosphate battery was charged to 100% SOC. The batteries were arranged side-by-side in close proximity, and electric heating elements were installed on the sides of the batteries. The heating elements had dimensions of 180mm × 140mm × 2mm, a rated power of 800W, and a supply voltage of AC 220V. The battery was heated until thermal runaway occurred. After the battery released a large amount of flammable gas, the extinguishing and explosion suppression device was activated 15 minutes later, releasing 21.48kg of liquid nitrogen. During the experiment, the liquid nitrogen rapidly reduced the battery surface temperature after being sprayed onto the battery. The battery temperature below the liquid nitrogen spray nozzle dropped from 291℃ to -173℃ in 87 seconds, the gas production rate decreased significantly, and no combustion or explosion occurred.

[0139] A water gun fire extinguishing system includes the aforementioned liquid nitrogen quantity control system for extinguishing lithium-ion battery thermal runaway fires.

[0140] A computer program for implementing the liquid nitrogen quantity control method for extinguishing lithium-ion battery thermal runaway fires in the preferred embodiment described above.

[0141] An information data processing terminal for implementing the liquid nitrogen quantity control method for extinguishing lithium-ion battery thermal runaway fires in the above preferred embodiments.

[0142] A computer-readable storage medium includes instructions that, when executed on a computer, cause the computer to perform the liquid nitrogen quantity control method for extinguishing thermal runaway fires in lithium-ion batteries as described in the preferred embodiment above.

[0143] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented, in whole or in part, as a computer program product, the computer program product includes one or more computer instructions. When the computer program instructions are loaded or executed on a computer, all or part of the processes or functions described in the embodiments of the present invention are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that integrates one or more available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., a solid-state drive (SSD)).

[0144] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall fall within the scope of the technical solution of the present invention.

Claims

1. A method for controlling the amount of liquid nitrogen used in extinguishing thermal runaway fires in lithium-ion batteries, characterized in that, include: S1. Obtain basic data: Mass M of a single lithium-ion battery b Specific heat capacity C of lithium-ion batteries P The lowest temperature T1 during the stage where the lithium-ion battery's own temperature rise rate exceeds 0.02℃ / min; the highest temperature T2 during the stage where the battery surface temperature continuously rises; and the average temperature T inside the energy storage container. C Ambient temperature T of energy storage container Z The number of lithium-ion batteries that experienced thermal runaway, n; S2. Obtain the thermal energy generated during a thermal runaway fire in a single lithium-ion battery using basic data; specifically: First, the thermal runaway fire of a single lithium-ion battery is divided into the self-heating stage and the heat release stage. Then, the heat generated by a single lithium-ion battery in the two different stages was calculated separately: During its own heat generation stage: ; In the formula: Q1 is the total heat released by a single lithium-ion battery during its own heat generation phase; During the heat release phase: ; In the formula: m1, m2, m3, and m4 are fitted data, t is the time after an open flame appears inside the energy storage container, and Q2 is the heat released during the thermal runaway combustion stage of a single lithium-ion battery. S3. Obtain the endothermic heat from liquid nitrogen; specifically: The latent heat of liquid nitrogen can be calculated using the following formula: ； In the formula: W1 is the latent heat absorbed by liquid nitrogen; C n1 The latent heat of liquid nitrogen; M n Mass of liquid nitrogen; Calculate the heat absorbed by the temperature rise after liquid nitrogen vaporization using the following formula: ； In the formula: W2 is the heat absorbed by the liquid nitrogen upon vaporization; C n2 T is the specific heat capacity of nitrogen. n1 T represents the average temperature inside the energy storage container after liquid nitrogen vaporization. n2 This is the initial temperature after liquid nitrogen vaporization; S4. Calculate the amount of liquid nitrogen needed for fire extinguishing; specifically: Establish the energy conservation formula: ； In the formula: n is the number of lithium-ion batteries that have experienced thermal runaway; The heat loss coefficient is the coefficient of heat absorption. Calculate the mass of liquid nitrogen using the energy conservation formula: ； S5, Control the liquid nitrogen volume M 控 This makes M 控 Not less than M n .

2. The liquid nitrogen quantity control method for extinguishing lithium-ion battery thermal runaway fires according to claim 1, characterized in that, m1, m2, m3, and m4 are each 2.5 × 10 7 3.1×10 5 2060.7, 144.

99.

3. The liquid nitrogen quantity control method for extinguishing lithium-ion battery thermal runaway fires according to claim 1, characterized in that, 。 4. The liquid nitrogen quantity control method for extinguishing lithium-ion battery thermal runaway fires according to claim 1, characterized in that, T1 and T2 were obtained using EV-ARC testing.

5. A liquid nitrogen volume control system for extinguishing lithium-ion battery thermal runaway fires, characterized in that, include: Basic data acquisition module: Acquires basic data: Mass M of a single lithium-ion battery b Specific heat capacity C of lithium-ion batteries P The lowest temperature T1 during the stage where the lithium-ion battery's own temperature rise rate exceeds 0.02℃ / min; the highest temperature T2 during the stage where the battery surface temperature continuously rises; and the average temperature T inside the energy storage container. C Ambient temperature T of energy storage container Z The number of lithium-ion batteries that experienced thermal runaway, n; Single Lithium-ion Battery Thermal Energy Analysis Module: This module uses basic data to obtain the thermal energy generated when a single lithium-ion battery experiences thermal runaway or fire; specifically: First, the thermal runaway fire of a single lithium-ion battery is divided into the self-heating stage and the heat release stage. Then, the heat generated by a single lithium-ion battery in the two different stages was calculated separately: During its own heat generation stage: ; In the formula: Q1 is the total heat released by a single lithium-ion battery during its own heat generation phase; During the heat release phase: ; In the formula: m1, m2, m3, and m4 are fitted data, t is the time after an open flame appears inside the energy storage container, and Q2 is the heat released during the thermal runaway combustion stage of a single lithium-ion battery. Liquid nitrogen endothermic heat analysis module: This module acquires the endothermic heat of liquid nitrogen; specifically: The latent heat of liquid nitrogen can be calculated using the following formula: ； In the formula: W1 is the latent heat absorbed by liquid nitrogen; C n1 The latent heat of liquid nitrogen; M n Mass of liquid nitrogen; Calculate the heat absorbed by the temperature rise after liquid nitrogen vaporization using the following formula: ； In the formula: W2 is the heat absorbed by the liquid nitrogen upon vaporization; C n2 T is the specific heat capacity of nitrogen. n1 T represents the average temperature inside the energy storage container after liquid nitrogen vaporization. n2 This is the initial temperature after liquid nitrogen vaporization; Liquid nitrogen fire extinguishing dosage calculation module: Calculates the amount of liquid nitrogen needed for fire extinguishing; specifically: Establish the energy conservation formula: ； In the formula: n is the number of lithium-ion batteries that have experienced thermal runaway; The heat loss coefficient is the coefficient of heat absorption. Calculate the mass of liquid nitrogen using the energy conservation formula: ； Control module: controls the amount of liquid nitrogen M 控 This makes M 控 Not less than M n .

6. The liquid nitrogen volume control system for extinguishing lithium-ion battery thermal runaway fires according to claim 5, characterized in that, m1, m2, m3, and m4 are each 2.5 × 10 7 3.1×10 5 2060.7, 144.

99.

7. The liquid nitrogen volume control system for extinguishing lithium-ion battery thermal runaway fires according to claim 5, characterized in that, 。 8. The liquid nitrogen volume control system for extinguishing lithium-ion battery thermal runaway fires according to claim 5, characterized in that, T1 and T2 were obtained using EV-ARC testing.

9. An information data processing terminal for implementing the liquid nitrogen quantity control method for extinguishing lithium-ion battery thermal runaway fires as described in any one of claims 1-4.

10. A computer-readable storage medium comprising instructions, when executed on a computer, causing the computer to perform the liquid nitrogen quantity control method for extinguishing thermal runaway fires of lithium-ion batteries as described in any one of claims 1-4.

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