Simulation system for inhibiting thermal runaway of lithium battery by multi-particle-size water mist

Abstract

The invention relates to the technical field of lithium battery thermal runaway suppression, and discloses a simulation system for lithium battery thermal runaway suppression by multi-particle-size water mist, which comprises a data acquisition module for lithium battery temperature acquisition, the temperature monitoring module is used for monitoring and predicting the temperature of the lithium battery and correcting the output of the temperature monitoring unit to monitor and predict the temperature of the lithium battery; the water mist control module is used for controlling the spraying type of particle size water mist and controlling the spraying momentum of fog drops; the suppression analysis module is used for performing suppression result analysis on the thermal runaway of the lithium battery; the feedback module is used for feeding back battery thermal runaway temperature response data and a particle size water mist cooling effect; according to the invention, higher monitoring precision can be ensured, the diameter of water mist and the momentum of fog drops are allowed to be adjusted according to different conditions, and a targeted inhibition effect is realized.

Description

Technical Field

[0001] The invention relates to the technical field of thermal runaway suppression of lithium batteries and discloses a simulation system for thermal runaway suppression of lithium batteries by multi-diameter fine water mist. Background Art

[0002] In the simulation system of multi-particle water mist for thermal runaway suppression of lithium batteries, the shortcomings include the fact that the current atomization technology may not be able to achieve the ideal particle size distribution, resulting in uneven coverage of the water mist, affecting the suppression effect. In practical applications, the uneven distribution of water mist may cause some areas to be too wet and other areas to be dry, thereby reducing the overall fire extinguishing efficiency. The existing theoretical model may not fully consider the impact of multi-particle water mist on heat transfer, resulting in a gap between the simulation results and the actual effects. There is a lack of systematic optimization research on various parameters (such as particle size, spray speed, etc.), which affects the maximization of the suppression effect. In practical applications, the safety assessment of the water mist system is still insufficient, and the potential impact of water mist on batteries and the surrounding environment needs to be considered.

[0003] For example, the invention with the existing patent publication number CN117148196A discloses a lithium battery water mist fire extinguishing performance test device and method, the device includes: a fire extinguishing test end, used to simulate the thermal runaway scene and fire extinguishing process of the lithium battery pack; a data acquisition end, used to collect fire extinguishing process data; and a control end, used to set different parameters. When using this device for experiments, various parameters of the fine water mist are set through the fire extinguishing test end, and data is collected and compared for multiple experimental groups with different fine water mist parameters, the fire extinguishing effect of each group is analyzed, and the influence of the fine water mist parameters on the fire extinguishing effect is studied. The invention proposes a lithium battery water mist fire extinguishing performance test device and method, which can simultaneously test the different effects of parameters such as droplet particle size, droplet spraying state, and droplet spray dispersion angle on the fine water mist fire extinguishing performance, and provide an efficient fire extinguishing basis for the practical application of fine water mist.

[0004] The shortcomings of the above invention are: the particle size distribution is not taken into account, resulting in uneven coverage of the water mist, affecting the suppression effect; only the effect of fine mist on fire extinguishing is considered, and temperature transfer and heat exchange are not considered, resulting in poor fire extinguishing performance. Summary of the invention

[0005] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0006] In order to solve the above technical problems, the main purpose of the present invention is to provide a multi-size fine water mist thermal runaway suppression simulation system for lithium batteries, comprising:

[0007] A data acquisition module, including a temperature acquisition unit, a light acquisition unit and a data processing unit;

[0008] A temperature monitoring module, comprising a temperature monitoring unit, a monitoring correction unit and a temperature classification unit, wherein the temperature monitoring unit is used to monitor and predict the lithium battery temperature, and the monitoring correction unit is used to correct the monitored and predicted lithium battery temperature output by the temperature monitoring unit;

[0009] A water mist control module, comprising a water mist diameter control unit, a mist droplet momentum control unit and a suppression effect analysis unit, wherein the water mist diameter control unit is used to control the type of particle size fine water mist spraying, and the mist droplet momentum control unit is used to control the mist droplet spraying momentum;

[0010] An inhibition analysis module, including a data integration unit and a thermal inhibition analysis unit;

[0011] The feedback module is used to feed back the temperature response data of suppressing battery thermal runaway to the temperature monitoring module, output the battery temperature data to the water mist control module through the temperature monitoring module, and control the water mist diameter through the water mist control module.

[0012] As a preferred solution of the multi-size water mist simulation system for thermal runaway suppression of lithium batteries of the present invention, wherein:

[0013] The temperature acquisition unit includes a temperature sensor for collecting the temperature of the lithium battery surface and the surrounding environment;

[0014] The light collection unit includes a photodiode for collecting ambient light intensity and analyzing the thermal state of the battery;

[0015] The data processing unit is used to process the collected surface temperature, ambient temperature and light intensity of the lithium battery.

[0016] As a preferred solution of the multi-size water mist simulation system for thermal runaway suppression of lithium batteries of the present invention, wherein:

[0017] The temperature monitoring unit is used to monitor the surface temperature data of the lithium battery and extract the characteristic value of the temperature data. The specific implementation steps include:

[0018] S101, receiving the processed data of the temperature, ambient temperature and light intensity of the lithium battery surface, and performing integration classification and normalization processing, by converting the time series temperature data into a two-dimensional array as the input of the temperature monitoring unit;

[0019] S102, setting a plurality of temperature feature extraction layers, extracting temperature change features from the two-dimensional time series temperature data, and reducing the data dimension of the time series temperature data, retaining the temperature change features;

[0020] S103, mapping and flattening the retained temperature change features through a fully connected layer, and performing classification regression through the fully connected layer to predict the temperature of the lithium battery at the next moment;

[0021] S104, outputting the current temperature, predicting the temperature of the lithium battery at the next moment, and the temperature classification status of the lithium battery through the temperature monitoring unit.

[0022] As a preferred solution of the multi-size water mist simulation system for thermal runaway suppression of lithium batteries of the present invention, wherein:

[0023] The temperature monitoring unit calculates the temperature change of the lithium battery over time as shown below:

[0024]

[0025] Among them, C is the heat capacity of the lithium battery, T is the current temperature of the lithium battery, t is the time series, R is the resistance of the battery itself, T che is the additional heat generated by the lithium battery during the electrochemical reaction, γ is the convection heat transfer coefficient, A is the surface area of ​​the lithium battery, T am is the ambient temperature of the lithium battery, m c is the particle size water mist flow rate, c p is the specific heat capacity of water, T cool is the cooling temperature of the lithium battery, and I is the current emitted by the lithium battery.

[0026] As a preferred solution of the multi-size water mist simulation system for thermal runaway suppression of lithium batteries of the present invention, wherein:

[0027] The temperature classification unit is used to organize the monitored lithium battery temperature data and classify the lithium battery temperature data. The classified data includes lithium battery heat release data, water mist heat absorption data, natural heat dissipation data, battery peak temperature, thermal runaway peak temperature when water mist is treated, lithium battery surface temperature when water mist stops, fine water mist cooling action time, and cooling rate;

[0028] The classified data are used to control the water mist diameter and the momentum of the droplets.

[0029] As a preferred solution of the multi-size water mist simulation system for thermal runaway suppression of lithium batteries of the present invention, wherein:

[0030] The water mist diameter control unit is used to control the spraying mode and spraying diameter of the particle size fine water mist;

[0031] The process of controlling the particle size of water mist spraying is as follows:

[0032] S201, receiving the lithium battery classification temperature monitoring value and temperature prediction value output by the temperature monitoring module, and calculating the battery heat generation according to the lithium battery classification temperature monitoring value and temperature prediction value;

[0033] S202, calculating the momentum of the mist droplets, determining whether the temperature characteristics of the lithium battery can be penetrated by the mist droplets, and directly cooling the battery surface; if the mist droplet momentum is sufficient to penetrate, mist droplet impact heat exchange is performed; if the mist droplet momentum is insufficient to penetrate, mist droplet evaporation heat absorption is performed; if part of the mist droplet momentum can penetrate, but part cannot penetrate, liquid film flow heat exchange is performed;

[0034] S203, calculating the maximum amount of heat absorbed by the droplets, and spraying water mist through a water mist diameter control unit;

[0035] S204. Approximately calculate the amount of heat actually absorbed by the water mist using data from the battery surface temperature feedback.

[0036] A preferred solution for a multi-size water mist simulation system for thermal runaway suppression of lithium batteries, wherein:

[0037] The monitoring correction unit is used to correct the loss of lithium battery temperature monitoring. The difference between the predicted temperature change rate and the actual temperature change rate is calculated to obtain the loss value, which is fed back to the temperature monitoring unit to correct and fine-tune the temperature feature extraction layer weight of the temperature monitoring unit.

[0038] As a preferred solution of the multi-size water mist simulation system for thermal runaway suppression of lithium batteries of the present invention, wherein:

[0039] The loss calculation expression is as follows:

[0040]

[0041] Among them, f t+1 * (T) is the predicted value of lithium battery temperature output by the temperature monitoring unit at time t+1, is the temperature prediction value of the lithium battery output by the temperature monitoring unit at time t, Δt is the time interval between two adjacent time points, and f t+1 (T) is the actual temperature of the lithium battery at time t+1, f t (T) is the actual temperature value of the lithium battery at time t, L is the loss value of the lithium battery temperature monitored by the temperature monitoring unit, and N is the total time.

[0042] As a preferred solution of the multi-size water mist simulation system for thermal runaway suppression of lithium batteries of the present invention, wherein:

[0043] The data integration unit is used to integrate the thermal runaway peak temperature of small-particle water mist, large-particle water mist and mixed-particle water mist, the surface temperature of the battery when the water mist stops, the cooling time of the water mist, the cooling rate, the mass loss, and the outer surface temperature of the lithium battery;

[0044] The heat suppression analysis unit is used to receive the data integrated by the data integration unit and analyze the heat suppression of the lithium battery. The utilization rate of the cooling capacity of the fine water mist is described by the cooling proportional coefficient. If the cooling proportional coefficient is larger, the utilization rate of the fine water mist is higher and the cooling effect is better.

[0045] As a preferred solution of the multi-size water mist simulation system for thermal runaway suppression of lithium batteries of the present invention, wherein:

[0046] The cooling efficiency of water mist can be determined by the average heat dissipation rate and cooling ratio coefficient;

[0047] The feedback module is used as the data communication point to feed back the real-time temperature of the lithium battery to the temperature monitoring module; the average heat dissipation rate and cooling ratio coefficient are fed back to the water mist control module to adjust the release efficiency of the particle size fine water mist.

[0048] Beneficial effects of the present invention:

[0049] The temperature collection unit and the light collection unit provided in the present invention provide real-time data, so that the system can respond to changes in time and ensure higher monitoring accuracy. The monitoring correction unit and the temperature classification unit improve the reliability of temperature data and can better identify and classify different thermal runaway states. The design of the water mist control module allows the water mist diameter and droplet momentum to be adjusted according to different situations to achieve targeted suppression effects. The suppression analysis unit provides a comprehensive effect evaluation through data integration and thermal suppression analysis, which helps to optimize the suppression strategy. The feedback module forms a closed-loop control to ensure that the temperature data can be quickly fed back to the water mist control module to improve the response speed and suppression efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0051] Figure 1 This is a composition diagram of a multi-size fine water mist simulation system for suppressing thermal runaway of lithium batteries according to the present invention;

[0052] Figure 2 It is a simulation curve of the thermal runaway temperature response of a lithium battery of a multi-particle water mist to a lithium battery thermal runaway suppression simulation system of the present invention;

[0053] Figure 3 It is a temperature simulation curve of a multi-particle water mist for suppressing thermal runaway of a lithium battery by a small-particle water mist in a simulation system for suppressing thermal runaway of a lithium battery of the present invention;

[0054] Figure 4 It is a temperature simulation curve of a multi-particle water mist for suppressing thermal runaway of a lithium battery by using a large-particle water mist in a simulation system for suppressing thermal runaway of a lithium battery according to the present invention;

[0055] Figure 5 This is a temperature simulation curve of a mixed particle size water mist suppressing thermal runaway of a lithium battery in a multi-particle size fine water mist simulation system of the present invention. DETAILED DESCRIPTION

[0056] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0057] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0058] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0059] Embodiment 1:

[0060] like Figure 1 As shown, a multi-size water mist thermal runaway suppression simulation system for lithium batteries includes:

[0061] A data acquisition module, including a temperature acquisition unit, a light acquisition unit and a data processing unit;

[0062] The temperature collection unit includes a temperature sensor for collecting the temperature of the lithium battery surface and the surrounding environment;

[0063] The light collection unit includes a photodiode for collecting ambient light intensity and analyzing the battery thermal state;

[0064] Furthermore, the thermal state of the battery includes the lithium battery overheating, emitting flames to produce jet fire, safe exhaust, stable combustion, etc.

[0065] The specific implementation method for thermal runaway and temperature collection of lithium batteries is as follows: the battery is continuously heated by a 120W heating rod until thermal runaway is triggered, and the heating rod switch is immediately turned off. In order to solve the problem of uneven battery surface temperature, the lithium battery is heated until thermal runaway, and the temperature rise and fall values ​​of the lithium battery surface are collected. Figure 2As shown in the figure, first, the battery temperature rise rate is relatively slow due to external heating by the heating rod. As the temperature continues to rise, a series of exothermic reactions begin to occur inside the battery, such as thermal decomposition of the SEI film and various reactions between the electrode material and the electrolyte. When the gas accumulated inside the battery reaches a certain pressure, which is greater than the load value of the safety valve, the safety valve pops open and a large amount of gas continues to overflow. At this moment, the temperature of different parts of the battery is around 148.3℃. After 64s, a 2s jet fire appears above the battery, thermal runaway is triggered, and the battery surface temperature rises sharply to 701.8℃, and the jet fire turns into stable combustion. After 25s, the flame gradually goes out, and the battery temperature also begins to gradually decrease. Due to the influence of the heating rod and the internal temperature of the battery, the unevenness of the battery surface temperature begins to appear. The temperature of the part close to the heating rod drops slower than that of the part far from the heating rod, but after reaching 100℃, the temperature tends to be consistent again. T1 is the position of the lithium battery far from the heating rod, and T2 is the position of the lithium battery close to the heating rod.

[0066] The data processing unit is used to process the collected temperature, ambient temperature and light intensity of the lithium battery surface;

[0067] Furthermore, the processing means include filtering and rectification, removing noise environment interference and sudden images to ensure the accuracy of the collected data;

[0068] Filtering and Rectification The analog temperature and light intensity signals are filtered through a low-pass filter to remove high-frequency noise, and a rectifier is used to convert the analog signals into digital signals.

[0069] Remove noise and interference through smoothing, averaging and weighted filtering to reduce noise levels and eliminate environmental interference, and remove sudden image interference through peak detection and de-burst processing.

[0070] The processed temperature and light intensity data are calibrated to remove the effects of sensor bias and environmental factors. For example, the battery surface temperature can be compared to the ambient temperature and adjusted using a calibration factor.

[0071] A temperature monitoring module, including a temperature monitoring unit, a monitoring correction unit and a temperature classification unit;

[0072] The temperature monitoring unit is used to monitor the surface temperature data of the lithium battery and extract the characteristic value of the temperature data. The specific implementation steps include:

[0073] S101, receiving the processed data of the temperature, ambient temperature and light intensity of the lithium battery surface, and performing integration classification and normalization processing, by converting the time series temperature data into a two-dimensional array as the input of the temperature monitoring unit;

[0074] S102, setting a plurality of temperature feature extraction layers, extracting temperature change features from the two-dimensional time series temperature data, and reducing the data dimension of the time series temperature data, retaining the temperature change features;

[0075] S103, mapping and flattening the retained temperature change features through a fully connected layer, and performing classification regression through the fully connected layer to predict the temperature of the lithium battery at the next moment;

[0076] S104, outputting the current temperature, predicting the temperature of the lithium battery at the next moment, and the temperature classification status of the lithium battery through the temperature monitoring unit.

[0077] The temperature monitoring unit calculates the temperature change of the lithium battery over time as shown below:

[0078]

[0079] Among them, C is the heat capacity of the lithium battery, T is the current temperature of the lithium battery, t is the time series, R is the resistance of the battery itself, T che is the additional heat generated by the lithium battery during the electrochemical reaction, γ is the convection heat transfer coefficient, A is the surface area of ​​the lithium battery, T am is the ambient temperature of the lithium battery, m c is the particle size water mist flow rate, c p is the specific heat capacity of water, T cool is the cooling temperature of the lithium battery, and I is the current emitted by the lithium battery.

[0080] Furthermore, the classification status includes normal, warning, alarm, etc.

[0081] The temperature monitoring unit based on neural convolutional networks can effectively predict temperature changes and provide real-time monitoring for lithium batteries to ensure their safety and performance reliability. By combining deep learning technology, the system has significant advantages in processing complex data patterns.

[0082] Furthermore, the monitoring correction unit is used to correct the loss of lithium battery temperature monitoring. By calculating the difference between the predicted temperature change rate and the actual temperature change rate, the loss value is obtained and fed back to the temperature monitoring unit to correct and fine-tune the weight of the temperature feature extraction layer of the temperature monitoring unit. The loss calculation expression is as follows:

[0083]

[0084] Among them, f t+1 * (T) is the predicted value of lithium battery temperature output by the temperature monitoring unit at time t+1, is the temperature prediction value of the lithium battery output by the temperature monitoring unit at time t, Δt is the time interval between two adjacent time points, and f t+1(T) is the actual temperature of the lithium battery at time t+1, f t (T) is the actual temperature value of the lithium battery at time t, L is the loss value of the lithium battery temperature monitored by the temperature monitoring unit, and N is the total time;

[0085] The temperature classification unit is used to organize the monitored lithium battery temperature data and classify the lithium battery temperature data. The classified data includes lithium battery heat release data, water mist heat absorption data, natural heat dissipation data, battery peak temperature, thermal runaway peak temperature when water mist is treated, lithium battery surface temperature when water mist stops, fine water mist cooling time, cooling rate, etc. The classified data is used to control the water mist diameter and control the momentum of the droplets;

[0086] Furthermore, the temperature feature extraction layer weights are used to extract features from the lithium battery temperature data.

[0087] A water mist control module, including a water mist diameter control unit, a mist droplet momentum control unit and a suppression effect analysis unit;

[0088] Among them, the water mist diameter control unit is used to control the particle size fine water mist spraying mode and spraying diameter;

[0089] The spraying process of particle size fine water mist control is as follows:

[0090] S201, receiving the lithium battery classification temperature monitoring value and temperature prediction value output by the temperature monitoring module, and calculating the battery heat generation according to the lithium battery classification temperature monitoring value and temperature prediction value;

[0091] S202, calculating the momentum of the mist droplets, determining whether the temperature characteristics of the lithium battery can be penetrated by the mist droplets, and directly cooling the battery surface; if the mist droplet momentum is sufficient to penetrate, mist droplet impact heat exchange is performed; if the mist droplet momentum is insufficient to penetrate, mist droplet evaporation heat absorption is performed; if part of the mist droplet momentum can penetrate, but part cannot penetrate, liquid film flow heat exchange is performed;

[0092] The calculation expression of the momentum of the droplet is as follows:

[0093]

[0094] Among them, Q is the momentum of the droplet, D is the particle size of the droplet, U is the lateral velocity of the droplet in three-dimensional space, V is the longitudinal velocity of the droplet in three-dimensional space, and W is the vertical axis velocity of the droplet in three-dimensional space; further, Used to calculate the spraying range of particle size water mist.

[0095] S203, calculating the maximum amount of heat absorbed by the droplets, and spraying water mist through a water mist diameter control unit;

[0096] S204, approximately calculating the amount of heat actually absorbed by the water mist based on the data fed back from the battery surface temperature;

[0097] The calculation expression of the maximum absorbed heat of water mist is as follows:

[0098] M=m w ×c w ×(T boi -T0)+h f ×m w

[0099] Where M is the maximum absorbed heat of water mist, m w is the mass used for water mist, c w is the specific heat capacity of water, T boi is the boiling point of water, T0 is the initial temperature of water, h f is the latent heat of evaporation of water;

[0100] The actual heat absorbed by the water mist is calculated as follows:

[0101] Q′ w =c w m b (T m1 -T m2 )+c w m r (T m2 -T c )

[0102] Among them, m b Is the original quality of the battery; T m1 is the peak temperature of thermal runaway without water mist; T m2 is the peak temperature of thermal runaway in the presence of water mist; T c Q′ is the surface temperature of the battery when the water mist stops. w is the actual amount of heat absorbed by the water mist, m r It is the residual mass of the battery after thermal runaway.

[0103] The droplet momentum control unit is used to control the diameter of the water mist spray, and the water mist diameter includes small-size fine water mist, large-size fine water mist and mixed-size fine water mist;

[0104] Furthermore, the diameter of the small-particle water mist droplets is very small. The surface area of ​​the same volume of water increases dramatically. Under the action of flame and high temperature, it will evaporate rapidly, reducing the oxygen content of the entire space. The droplets also absorb a large amount of heat during the evaporation process, reducing the temperature of the battery surface and the surrounding air, and have excellent heat exchange capacity. The specific implementation method is as follows: Figure 3As shown in the figure, compared with the thermal runaway process without the effect of fine water mist, when the battery produces jet fire and releases fine water mist, although the battery surface temperature continues to rise for a period of time, the maximum temperature reached by thermal runaway has dropped significantly. When no fine water mist is applied, the average maximum temperature can reach 695°C, and under the cooling effect of fine water mist, the average maximum temperature reaches 659.7°C. With the continuous release of fine water mist, its cooling rate begins to be greater than the heat generation rate of the battery thermal runaway, and the battery surface temperature begins to drop rapidly. Since the internal temperature of the battery is higher than the surface temperature, when the release of fine water mist stops, the battery surface temperature still rebounds to a certain extent, and then naturally cools down. Among them, Figure 3 The 50℃ temperature stabilization line means that when the battery surface temperature is stabilized below 50℃, the water mist system stops. Figure 3 T1 is the battery surface temperature without spraying small-particle water mist. The battery stops working at 400s, and the maximum temperature is 695°C. T2 is the temperature simulation diagram of spraying small-particle water mist.

[0105] Further, such as Figure 4 As shown in the figure, the battery surface temperature change curve in the process of suppressing thermal runaway of lithium battery by using 194.6μm fine water mist. By reducing the spray pressure of the nozzle and increasing the size of the spray particle size, the maximum temperature of thermal runaway is not well suppressed, and its average maximum temperature is 690℃, which is similar to the thermal runaway process without the application of fine water mist. In the continuous cooling process, the temperature drops slowly at the beginning, and then drops sharply in the middle. After dropping to 100℃, the cooling rate tends to be flat again. After gradually cooling to 50℃, the application of fine water mist is stopped, and the temperature does not rise again. Figure 4 In the figure, T1 is a temperature simulation diagram of a lithium battery sprayed with fine water mist of small particle size, and T2 is a temperature simulation diagram of a lithium battery sprayed with fine water mist of large particle size;

[0106] Further, such as Figure 5 As shown in the figure, the temperature change curve of the battery surface during the thermal runaway of the lithium battery is suppressed by combining two fine water mists of different particle sizes. Figure 5 T1 is a temperature simulation diagram of a lithium battery sprayed with large-particle water mist, and T2 is a temperature simulation diagram of a lithium battery sprayed with mixed-particle water mist;

[0107] because Figure 3 , Figure 4 , Figure 5 These are all independent experiments, so the temperature responses of lithium batteries under the same water mist conditions are slightly different.

[0108] an inhibition analysis unit, including a data integration unit and a thermal inhibition analysis unit;

[0109] The data integration unit is used to integrate the thermal runaway peak temperature of small-particle water mist, large-particle water mist and mixed-particle water mist, the surface temperature of the battery when the water mist stops, the cooling time of the water mist, the cooling rate, the mass loss, the outer surface temperature of the lithium battery, etc.;

[0110] The heat suppression analysis unit is used to receive the data integrated by the data integration unit and analyze the heat suppression of the lithium battery. The cooling ratio coefficient is used to describe the utilization rate of the cooling capacity of the fine water mist. If the cooling ratio coefficient is larger, the utilization rate of the fine water mist is higher and the cooling effect is better. The cooling capacity of the fine water mist is further evaluated by the average heat dissipation rate of the lithium battery.

[0111] Furthermore, the cooling proportional coefficient calculation expression is as follows:

[0112]

[0113] Among them, λ is the cooling proportional coefficient, and the cooling effect of the water mist is calculated by the ratio of the maximum heat absorbed by the water mist to the heat actually absorbed by the water mist;

[0114] The average heat dissipation rate calculation expression is as follows:

[0115]

[0116] Among them, Δt is the cooling time of fine water mist, and δ is the average heat dissipation rate.

[0117] The feedback module is used to feed back the temperature response data of suppressing battery thermal runaway to the temperature monitoring module, output the battery temperature data to the water mist control module through the temperature monitoring module, and control the water mist diameter through the water mist control module.

[0118] Among them, the cooling efficiency of the water mist is determined by the average heat dissipation rate and the cooling ratio coefficient;

[0119] The feedback module is used as the data communication point to feed back the real-time temperature of the lithium battery to the temperature monitoring module, and the average heat dissipation rate and cooling ratio coefficient to the water mist control module;

[0120] Furthermore, the temperature monitoring module is fed back to monitor the temperature of the lithium battery in real time, and the particle size of the water mist is selected based on the temperature of the lithium battery;

[0121] The average heat dissipation rate and cooling ratio coefficient are fed back to the water mist control module to adjust the release efficiency of the particle size fine water mist, thereby improving the utilization rate of the particle size fine water mist and saving resources.

[0122] Embodiment 2:

[0123] The effects of different water mist application methods on thermal runaway suppression of lithium batteries in Example 1 also include:

[0124] When thermal runaway of a lithium battery is triggered, a series of chemical reactions inside the battery continuously release heat, causing the temperature inside the battery to continue to rise. Under the influence of the temperature gradient, the temperature on the surface of the battery also rises sharply. Once thermal runaway is triggered, it cannot be stopped, and the cooling effect of fine water mist can only reduce the peak temperature of the battery. If you want to quickly reduce the temperature of the battery in a short period of time without causing a greater risk of fire spread, the principle of fine water mist is to separate liquid water into fine water droplets through a nozzle, increase the surface area of ​​the water, and increase the contact area between water and heat source, ultimately achieving the purpose of extinguishing the fire. At the same time, since the particle size of the water droplets is very small and the inertia is small, it will not cause great damage to equipment and human body. Moreover, during the spraying of fine water mist, not only the temperature of the battery surface is reduced, but also the temperature of the surrounding air and the concentration of smoke generated during the thermal runaway of the battery are reduced, which can effectively extend the rescue time and ensure the safety of personnel's lives. For the process of cooling the battery with fine water mist, there are three main ways of heat exchange: droplet evaporation heat absorption, droplet impact heat exchange, and liquid film flow heat exchange. From Figure 3 , Figure 4 It can be seen that in the water mist cooling stage I, the small-particle water mist not only effectively reduces the peak temperature, but also reduces the temperature faster than the large-particle water mist. In the cooling stage II, the cooling effect of the small-particle water mist is obviously getting worse and worse in the later stage, and the temperature rises after the battery temperature drops below 50°C. At this time, the large-particle water mist shows outstanding advantages. The cooling effect in the later stage shows a cliff-like downward trend, and there is no temperature recovery after dropping below 50°C, indicating that the battery thermal runaway has been completely suppressed. Lowering the battery temperature to below 50°C in such a short time can effectively prevent the high temperature of a single battery from being transferred to adjacent batteries, thereby avoiding unnecessary thermal runaway propagation. When the droplets are sprayed downward and interact with the flame, the droplets must pass through the fire plume to reach the battery surface. Therefore, to a certain extent, the momentum of the droplets affects whether the droplets can penetrate the fire plume to directly cool the battery surface.

[0125] The specific implementation includes: setting the specific heat capacity of water (4.2 kJ / kg·℃); the boiling point of water (100℃); the initial water temperature (25℃); the latent heat of evaporation of water (2257 kJ / kg); the test battery is a standard experimental lithium battery, and the inhibitory effect of fine water mist of different particle sizes on thermal runaway of lithium batteries is obtained:

[0126]

[0127] Table 1, Quantitative analysis parameters of the effect of different water mist application methods on the thermal runaway inhibition of lithium batteries;

[0128] Through Table 1, Figure 3 , Figure 4 and Figure 5 It can be seen that:

[0129] Small-particle water mist WM1 (101.7μm) exhibits excellent cooling ability in the early stage of thermal runaway cooling, and directly reduces the thermal damage caused by thermal runaway by lowering the peak temperature during the thermal runaway process. Large-particle water mist WM2 (194.6μm) has a cliff-like cooling effect in the later stage of thermal runaway cooling, which directly greatly shortens the overall cooling time and increases the cooling rate to four times the natural cooling rate.

[0130] The cooling efficiency of mixed particle size water mist WM1+WM2 is significantly better than that of single particle size water mist. It not only directly reduces the peak temperature during thermal runaway, but also shortens the cooling time, which is significantly better than the natural cooling time of thermal runaway of 1287s. The cooling rate is increased to six times the natural cooling rate.

[0131] In the process of suppressing thermal runaway of lithium batteries, the high specific heat capacity and strong evaporation ability of water mist not only enable it to effectively extinguish fires but also provide continuous cooling during the fire extinguishing process. However, in practical applications, high water consumption still causes many secondary disasters. The mixed particle size water mist application method can not only effectively shorten the cooling time, but also greatly reduce water consumption. From the perspective of the average heat dissipation rate analysis results, the average heat dissipation of this method far exceeds the heat dissipation rate of single particle size water mist, which directly and effectively improves the full utilization rate of water.

[0132] Importantly, it should be noted that the construction and arrangement of the present application shown in a plurality of different exemplary embodiments are only exemplary. Although only two embodiments are described in detail in this disclosure, it should be readily understood by those who refer to this disclosure that many modifications are possible, for example, the size, scale, structure, shape and ratio of various elements, and parameter values ​​(e.g., temperature, pressure, etc.), installation arrangement, use of materials, color, directional changes, etc., without substantially departing from the novel teachings and advantages of the subject matter described in the application. For example, the element shown as integrally formed can be composed of multiple parts or elements, the position of the element can be inverted or otherwise changed, and the nature or number or position of the discrete element can be changed or changed. Therefore, all such modifications are intended to be included in the scope of the present invention. The order or sequence of any process or method step can be changed or reordered according to an alternative embodiment. Any "device plus function" clause is intended to cover the structure of the execution function described in this article, and is not only structurally equivalent but also equivalent structure. Without departing from the scope of the present invention, other replacements, modifications, changes and omissions can be made in the design, operating conditions and arrangement of the exemplary embodiment. Therefore, the invention is not limited to a specific embodiment, but extends to several modifications still falling within the scope of the appended claims.

[0133] Additionally, in order to provide a concise description of exemplary embodiments, all features of an actual embodiment (ie, those features that are not relevant to the best mode presently contemplated for carrying out the invention or those that are not relevant to implementing the invention) may not be described.

[0134] It should be understood that in the development of any actual implementation, as in any engineering or design project, numerous implementation-specific decisions may be made. Such a development effort may be complex and time-consuming, but for those of ordinary skill having the benefit of this disclosure, the development effort will be a routine task of design, fabrication, and production without undue experimentation.

[0135] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A multi-size water mist simulation system for thermal runaway suppression of lithium batteries, characterized in that: include: A data acquisition module, including a temperature acquisition unit, a light acquisition unit and a data processing unit; A temperature monitoring module, comprising a temperature monitoring unit, a monitoring correction unit and a temperature classification unit, wherein the temperature monitoring unit is used to monitor and predict the lithium battery temperature, and the monitoring correction unit is used to correct the monitored and predicted lithium battery temperature output by the temperature monitoring unit; A water mist control module, comprising a water mist diameter control unit, a mist droplet momentum control unit and a suppression effect analysis unit, wherein the water mist diameter control unit is used to control the type of particle size fine water mist spraying, and the mist droplet momentum control unit is used to control the mist droplet spraying momentum; An inhibition analysis module, including a data integration unit and a thermal inhibition analysis unit; The feedback module is used to feed back the temperature response data of suppressing battery thermal runaway to the temperature monitoring module, output the battery temperature data to the water mist control module through the temperature monitoring module, and control the water mist diameter through the water mist control module.

2. According to claim 1, a multi-particle water mist simulation system for thermal runaway suppression of lithium batteries is characterized by: The temperature acquisition unit includes a temperature sensor for collecting the temperature of the lithium battery surface and the surrounding environment; The light collection unit includes a photodiode for collecting ambient light intensity and analyzing the thermal state of the battery; The data processing unit is used to process the collected surface temperature, ambient temperature and light intensity of the lithium battery.

3. According to claim 2, a multi-particle water mist simulation system for suppressing thermal runaway of lithium batteries is characterized in that: The temperature monitoring unit is used to monitor the surface temperature data of the lithium battery and extract the characteristic value of the temperature data. The specific implementation steps include: S101, receiving the processed data of the temperature, ambient temperature and light intensity of the lithium battery surface, and performing integration classification and normalization processing, by converting the time series temperature data into a two-dimensional array as the input of the temperature monitoring unit; S102, setting a plurality of temperature feature extraction layers, extracting temperature change features from the two-dimensional time series temperature data, and reducing the data dimension of the time series temperature data, retaining the temperature change features; S103, mapping and flattening the retained temperature change features through a fully connected layer, and performing classification regression through the fully connected layer to predict the temperature of the lithium battery at the next moment; S104, outputting the current temperature, predicting the temperature of the lithium battery at the next moment, and the temperature classification status of the lithium battery through the temperature monitoring unit.

4. According to claim 3, a multi-particle water mist simulation system for suppressing thermal runaway of lithium batteries is characterized in that: The temperature monitoring unit calculates the temperature change of the lithium battery over time as shown below: Among them, C is the heat capacity of the lithium battery, T is the current temperature of the lithium battery, t is the time series, R is the resistance of the battery itself, T che is the additional heat generated by the lithium battery during the electrochemical reaction, γ is the convection heat transfer coefficient, A is the surface area of ​​the lithium battery, T am is the ambient temperature of the lithium battery, m c is the particle size water mist flow rate, c p is the specific heat capacity of water, T cool is the cooling temperature of the lithium battery, and I is the current emitted by the lithium battery.

5. The multi-size water mist simulation system for thermal runaway suppression of lithium batteries according to claim 4, characterized in that: The temperature classification unit is used to organize the monitored lithium battery temperature data and classify the lithium battery temperature data. The classified data includes lithium battery heat release data, water mist heat absorption data, natural heat dissipation data, battery peak temperature, thermal runaway peak temperature when water mist is treated, lithium battery surface temperature when water mist stops, fine water mist cooling action time, and cooling rate; The classified data are used to control the water mist diameter and the momentum of the droplets.

6. The multi-size water mist simulation system for suppressing thermal runaway of lithium batteries according to claim 5, characterized in that: The water mist diameter control unit is used to control the spraying mode and spraying diameter of the particle size fine water mist; The process of controlling the particle size of the fine water mist spraying is as follows: S201, receiving the classified temperature monitoring value and the temperature prediction value of the lithium battery output by the temperature monitoring module, and calculating the heat generated by the battery according to the classified temperature monitoring value and the temperature prediction value of the lithium battery; S202, calculating the momentum of the mist droplets, determining whether the temperature characteristics of the lithium battery can be penetrated by the mist droplets, and directly cooling the battery surface; if the mist droplet momentum is sufficient to penetrate, mist droplet impact heat exchange is performed; if the mist droplet momentum is insufficient to penetrate, mist droplet evaporation heat absorption is performed; if part of the mist droplet momentum can penetrate, but part cannot penetrate, liquid film flow heat exchange is performed; S203, calculating the maximum amount of heat absorbed by the droplets, and spraying water mist through a water mist diameter control unit; S204. Approximately calculate the amount of heat actually absorbed by the water mist using data from the battery surface temperature feedback.

7. The multi-size water mist simulation system for thermal runaway suppression of lithium batteries according to claim 6, characterized in that: The monitoring correction unit is used to correct the loss of lithium battery temperature monitoring. The difference between the predicted temperature change rate and the actual temperature change rate is calculated to obtain the loss value, which is fed back to the temperature monitoring unit to correct and fine-tune the temperature feature extraction layer weight of the temperature monitoring unit.

8. The multi-size water mist simulation system for thermal runaway suppression of lithium batteries according to claim 7, characterized in that: The loss calculation expression is as follows: Among them, f t+1 * (T) is the predicted value of lithium battery temperature output by the temperature monitoring unit at time t+1, f t * (T) is the predicted temperature value of the lithium battery output by the temperature monitoring unit at time t, Δt is the time interval between two adjacent time points, and f t+1 (T) is the actual temperature of the lithium battery at time t+1, f t (T) is the actual temperature value of the lithium battery at time t, L is the loss value of the lithium battery temperature monitored by the temperature monitoring unit, and N is the total time.

9. The multi-size water mist simulation system for suppressing thermal runaway of lithium batteries according to claim 8, characterized in that: The data integration unit is used to integrate the thermal runaway peak temperature of small-particle water mist, large-particle water mist and mixed-particle water mist, the surface temperature of the battery when the water mist stops, the cooling time of the water mist, the cooling rate, the mass loss, and the outer surface temperature of the lithium battery; The heat suppression analysis unit is used to receive the data integrated by the data integration unit and analyze the heat suppression of the lithium battery. The utilization rate of the cooling capacity of the fine water mist is described by the cooling proportional coefficient. If the cooling proportional coefficient is larger, the utilization rate of the fine water mist is higher and the cooling effect is better.

10. The multi-size water mist simulation system for suppressing thermal runaway of lithium batteries according to claim 9, characterized in that: The cooling efficiency of water mist can be determined by the average heat dissipation rate and cooling ratio coefficient; The feedback module is used as the data communication point to feed back the real-time temperature of the lithium battery to the temperature monitoring module; the average heat dissipation rate and cooling ratio coefficient are fed back to the water mist control module to adjust the release efficiency of the particle size fine water mist.

Images