The nine-dimensional model proposed in this paper systematically characterizes the features of fire and explosion risk of lithium battery from the aspects of technology ontology, disaster energy, risk receptors, and management. The model is used to evaluate the disaster risk of three main application areas of lithium battery, namely mobile phone, electric bicycle, and electric vehicle. The fire and explosion risk caused by lithium battery in electric bicycle is found to be the highest. By analyzing the disaster procedure of lithium battery, some safety prevention measures are proposed from technical ontology constraints, risk causing energy control, energy release path shielding, and risk receptor protection respectively. The results provide support for the safety management of lithium battery technology, and also provide ideas for risk analysis and control of other new energy technologies.

High-rate overcharging can have a serious impact on the thermal safety of lithium-ion batteries. In order to explore the overcharge behavior and heat generation characteristics of 18650 ternary lithium-ion batteries applied in aircraft at different charging rates，based on the overcharge test platform, the changes of surface temperature, voltage, characteristic time, mass loss and heat production of lithium-ion batteries during overcharging are analyzed, and the heat production characteristics of batteries under different charging rates are quantitatively evaluated. The results show that the overcharging process of the battery can be divided into four stages according to the change of characteristic voltage：normal charging, lithium plating, side reactions between lithium plating and electrolyte, electrolyte decomposition and internal short circuit. As the charging rate increases, the maximum temperature on the surface of the battery increases，the temperature rise is more severe, the time required for battery failure is shorter, the mass loss increases linearly, and the safety becomes poorer. This is mainly due to the high charging rate resulting in rapid lithium plating, which in turn leads to side reactions inside the battery. The heat of side reaction is the main source of heat accumulated during battery overcharging, and its contribution to heat production decreases with the increase of charging rate. This study is helpful to accurately predict and evaluate the performance of aviation airborne batteries under extreme conditions, and provides a new idea for optimizing aircraft battery design and thermal management systems.

In order to study the fire behavior characteristics and influencing factors of banana water fuel in containers, container fire scenarios were designed under three opening states of the container doors (fully open, half open, and fully closed), four different positions of the fire source (shallow part, middle part, deep part, and corner of the container), and six wind speeds under three wind directions. The simulation results of FDS show that the opening state and the position of the fire source have a greater impact on the heat release rate, burning rate, and the temperature of the external container of the fire, while the impact of environmental wind changes is relatively small. There is a certain lag in both the rise of the smoke temperature and the occurrence time of the maximum value at positions away from the fire source. The average temperature at the center of the fire source under each working condition exhibits obvious stage characteristics, with a higher temperature in the upper area of the entire longitudinal section and a lower temperature in the lower area. The degree of influence of different factors on the evolution of the average temperature at the center of the fire source is as follows: position of the fire source > opening state > wind speed and direction. The research results have very important guiding significance for the prevention and extinguishing of container fires.

In order to simulate the ignition process of the outer sheath under the fault arc and investigate its ignition characteristics, this paper proposes an electrode arc ignition simulation method, based on the energy balance equation of the arc ignition process and experimental data, analyses the impact of the electrode speed and circuit current on the arc ignition stability, and determines the relationship between the different current conditions and the electrode speed and arc power. The results show that under the same circuit current condition, when the electrode moving speed is too fast, it will lead to a shorter arc ignition time and cannot ignite the outer sheath; while when the electrode speed is too slow, it will lead to the burning carbide connecting the two poles, and the arc will be extinguished prematurely, with a short combustion duration; there is a certain range of electrode speeds corresponding to different circuit current conditions, and both the upper limit and lower limit of the speed are positively correlated to the size of the circuit current. Using the relationship between the determined circuit current and the electrode speed, the simulation of the ignition of the outer sheath under the action of the arc is achieved by taking the 35 kV high-voltage cable as an example, which shows that the simulation method in this paper can successfully ignite the outer sheath of the high-voltage cable and sustained combustion occurs under the action of the arc.

To investigate the influence of different gas generator dosages and gas chamber volumes on the operational reliability of a gas-driven perfluorohexanone fire extinguishing device, this study references the technical requirements and testing methods outlined in relevant standards. The validation focuses on the injection time, injection process, and state of the fire extinguishing device with a charge amount of 0.8 kg of extinguishing agent. The research findings indicate that the activation of the safety release mechanism and suboptimal or ineffective injection of the extinguishing agent are primarily caused by a mismatch between the gas generator dosage and the gas chamber volume. It is essential to incorporate adequate safety margins when calculating the internal pressure of the fire extinguishing device to prevent failure in normal injection. Furthermore, consideration must be given to the heat generation of the gas generator to ensure that the theoretical calculations of internal pressure align closely with actual pressure values after activation of the fire extinguishing device. Consequently, adjusting the gas generator dosage and gas chamber volume based on the charge amount of the extinguishing agent can enhance the reliability of the fire extinguishing device and improve the atomization effect of the extinguishing agent, thereby achieving superior fire suppression performance

The effects of variable velocity on the explosion flame propagation characteristics and explosion overpressure characteristics of methane/air mixed fuel were studied by a self-built visual methane explosion experiment platform with a variable velocity small fan installed at the end of the pipeline to produce premixed gas flow with the same and opposite flame propagation direction. The results show that variable velocity gas flow can promote methane explosion combustion to some extent. With the increase of gas velocity, the effect of promoting methane explosion combustion gradually increases. However, with the increase of gas velocity, for single-phase convection gas, the effect of promoting methane explosion begins to decrease with the increase of opposite flow intensity. For a single homogeneous flow gas, with the increase of the intensity of the flow, it has been shown to promote the explosion of methane. At the same time, the flame oscillates when approaching the tail fan.

Increasing attention is being paid to safety concerns, particularly those associated with the risk of fires caused by the use of organic solvent electrolytes with high volatility and flammability. The fire hazards of electrolytes are closely linked to their chemical properties, as they are prone to thermal runaway under high temperature conditions, overcharging, and mechanical damage, leading to battery combustion or explosion. A comprehensive analysis of the fire hazards of electrolytes and their impact on the safety of lithium-ion batteries is presented in this paper. Research progress in the development of safer electrolyte materials since 2019 is reviewed from the perspectives of thermal stability, flame retardancy, and resistance to overcharging. The objective of this study is to provide a scientific foundation and reference for the design and development of safer electrolytes for future lithium-ion batteries.

In order to study the combustion characteristics of electric bicycles and the suppression efficiency of fire suppression systems on electric bicycles fires, physical fire tests of the single electric bicycle and fire extinguishing tests of electric bicycles in simulated bike shed are conducted. The suppression efficiency of hanging dry powder fire extinguisher and simple sprinkler system for the fire spreading of electric bicycles in bike shed are studied. The results show that the maximum temperature of the single electric bicycle fire is 646 ℃, the maximum heat release rate is 1 337 kW. Moreover, the phenomenon of jet fire is observed. In the fire extinguishing test, hanging powder extinguishing device can temporarily inhibit the open flame. After the action is completed, the fire is rekindled many times. In addition to the tested electric bicycle being completely burned, three other bicycles are also seriously damaged. The simple sprinkler system can quickly extinguish open flame and reduce the temperature of electric bicycles. And there is no obvious re-ignition phenomenon. During the test, only the tested electric bicycle is burned, and adjacent electric bicycles are not ignited. Therefore, the simple sprinkler system can be one of the effective measures to suppress the fires in centralized charging areas for electric bicycles.

In order to study the fire resistance effect of thin rendering layer on insulation material, cone calorimeter tests were conducted with a 50 kW/m2 radiant heat flux to simulate the thermal exposure of a large-scale window fire. The fire resistance effects of rendering layers were studied by comparing the combustion properties of polyurethane foam (PU), extruded polystyrene foam (XPS) and graphite extruded polystyrene foam (GXPS) and the fire resistance properties after applying the thin rendering layers with thicknesses of 3, 5 mm and 7 mm respectively. The results show that there are obvious differences in the combustion properties of the three insulation materials without rendering layer. The ignition and peak heat release rate (PHRR) times for PU are the shortest, and its PHRR is the lowest. With a rendering layer, though it does not prevent ignition, the fire resistance properties of each insulation material are significantly improved: the ignition time is prolonged, the PHRR, the peak smoke release rate (PSPR) and the total smoke production (TSP) are reduced, the fire performance index (FPI) is increased, and the fire growth index (FGI) is decreased, and the fire resistance effect is further enhanced with the increase of rendering layer thickness. The fire resistance mechanism is mainly due to the rendering layer reducing the temperature rise rate of the insulation layer, slowing the escape rate of the pyrolysis gas, and blocking the contact between materials and oxygen, thus reducing the fire risk.

In order to study the influence of shaft spacing on the ultimate height of the shaft chimney effect during fire, tunnel fires under four shaft cross-section sizes and five shaft spacing were simulated by FDS fire dynamics simulation software, focusing on the influence of shaft spacing on the ultimate height of chimney effect. The results show that the shaft chimney effect is enhanced with the increase of shaft height, but its ultimate height gradually decreases with the increase of shaft spacing; moreover, the influence of shaft spacing on the ultimate height of the shaft chimney effect gradually increases with the increase of shaft cross-section size. Based on the simulation data, the correlation between the limiting height z of the shaft chimney effect and the shaft spacing x and the side length of the shaft section y was obtained. The expression can estimate the ultimate height of the shaft chimney effect when 60 m≤x≤240 m and 0.5 m≤y≤2.5 m under the same environment, which provides guidance for the design of natural ventilation shafts, and is expected to provide a reference for the design of smoke vents of natural ventilation systems in related fields.

In order to improve the accuracy of the numerical substructure in the hybrid simulation of fire resistance, combined with the model updating technology, the hybrid simulation of fire resistance based on temperature field updating is carried out. A two stories and two spans steel frame model under fire is established to identify the measured temperature parameters in the experimental substructure. The element node temperature of the same part of the numerical substructure is updated to improve the calculation accuracy of the numerical substructure in the hybrid simulation. The results show that the method can update the temperature field of the model according to the data of the test substructure and analyze the fire resistance of the structure. The calculated fire resistance limit and ultimate stress state are in good agreement with the overall structure simulation. The error of fire resistance limit time is 7%, and the error of ultimate state stress is 1%. Therefore, the method proposed in this paper is more reliable and can provide a reference for further improving the applicability of the structural fire resistance hybrid test method.

Realizing dynamic classified emergency response for the whole process of fire evolution in subway station is an important basis for scientific and accurate fire emergency rescue and disposal. Based on the inherent fire danger and dynamic evolution characteristics of subway station, this study developed a subway station fire classified emergency response index system from 3 perspectives: static, semi-dynamic and dynamic, proposed a classification and quantitative characterization method for different categories of warning indicator data. The combination of analytic hierarchy process and complex network is used to determine the comprehensive weights of early warning indicators. The method of subway station fire classified emergency response is proposed based on technique for order preference by similarity to an ideal solution. Finally the dynamic classified emergency response evaluation method for subway station fire was constructed, and the subway station electromechanical equipment system working and emergency organization classification response strategy is proposed. The results can provide decision support for the whole process of emergency response and disposal of subway station fire.

To study the professional capacity of station-level commanders, based on previous research, this study obtains and constructs a pool of competency elements for station-level commanders through questionnaires, expert interviews, and other methods. Taking the SZ Fire and Rescue Division as an example, this study utilizes exploratory factor analysis to establish a competency model for station-level commanders and tests its validity through structural equation modeling. The research findings indicate that the competency model for station-level commanders primarily comprises five dimensions: knowledge level, ability and quality, political accomplishment, personality traits, and internal drive, encompassing 27 competency elements. Among these, internal drive and ability have the greatest impact on post competency, followed by knowledge level and political accomplishment, with personality traits having the least influence. The research results of this study can provide theoretical and methodological guidance for grassroots firefighting and rescue teams to carry out training, assessment, and selection of station-level commanders.

In order to enhance the lithium battery fire emergency response capabilities of cabin crew, solve the limitations of traditional fire drills such as single and fixed scenarios, difficulty in achieving multi-person cooperation, and subjectivity of evaluating ability, the "teaching-learning-test-evaluation" civil aviation cabin lithium battery fire VR emergency drill platform was developed based on Virtual Reality technology, which could achieve nonscript, overall process, evaluation and multi-person cooperation functions. Firstly, the CBTA-CRM model was proposed and designed to meet platform's drill requirements, functional framework, and evaluation dimensions. Secondly, the Untiy3D game engine and 3Dmax were used to realize the system development of platform scenes, characters and tasks. Thirdly, the modular development of software system was realized and linked with hardware system, which were completed and integrated with network data transmission system. Finally, taking the fire accident of lithium battery in the luggage rack and seats of passenger cabin as examples, the aviation crew were invited to cooperate in groups to conduct the whole process exercise. The results show that the VR drill platform can achieve the lithium battery fire emergency tasks, support the multi-person cooperative and nonscript emergency drills, and conduct overall process evaluation, which improves crews team cooperation and enhances the lithium battery fire emergency response capabilities.

In order to study the heat resistance for the new type tracked fire fighting robot chassis covered with aerogel insulation layer, the finite element analysis and experiment ware implemented respetively, and the traditional fire fighting robot chassis without aerogel insulation layer was also researched by contrast experiment in this paper. The results show that the temperature rise of the new type fire robot chassis after heating for 30 min is approximately 9.5 ℃, which is much lower than the 42 ℃ temperature rise of the traditional fire fighting robot chassis, and the temperature is lower nearby the middle and lower position inside the chassis box, where is more suitable to set electrical components. The new type fire fighting robot chassis in this paper shows better heat resistance, it will improve the technical level in fire fighting robot field.

In forest fires, extreme fire behaviors such as spotting and fire whirl frequently occur, which can ignite unburned areas ahead of the fire front and accelerate surface fire spread. This work selected a forest fire in Changjiang County, Hainan, on June 7, 2020, which occurred on flat terrain, as the research object. By altering the number of fire points and the rate of spread adjustment factor, the accuracy of fire spread simulation results using the FARSITE system was analyzed. The results showed that with the increase of the adjustment factor, the prediction accuracy first increases and then decreases. When the adjustment factor is 1, the intersection area under single ignition source conditions accounts for 5% of the actual burned area. Using four initial fire points and changing their positions, the intersection area proportions increased by 10% and 18%, respectively. When the optimal adjustment factor is reached, the fire spread simulation accuracy is the highest, and the intersection area proportion in the single fire source simulation increases to 72% with an accuracy of 0.70. Reasonably setting the locations and number of fire points could improve the accuracy of fire spread prediction, and reduce the impact of extreme fire behaviors or inaccuracies in model data on prediction results, but may also lead to overprediction of the burned area.

Compared to flaming combustion, smoldering has a lower reaction temperature and slower spread rate, and can persist under extreme conditions such as oxygen-limited environments, high moisture content, and deep underground. Therefore, the detection and extinguishing of smoldering wildland fires face greater challenges. This paper provides an overview of the past research on smoldering suppression at the laboratory scale from the perspectives of three basic mechanisms: quenching, smothering, and burnout. The feasibilities and possibilities of controlling smoldering fires through artificial rainfall, underground water injection, and the construction of firebreaks are summarized. Furthermore, the technologies and strategies for prevention, monitoring, and suppression in current wildland smoldering fire management practices are overviewed, providing insights for future theoretical research on smoldering fires and the development of new technologies based on artificial intelligence and digital twins.

This paper aims to study on the Pinus armandii forest after nurturing in the Yunnan Forest Nature Center through a combination of field surveys, indoor measurements, and simulated combustion tests, to analyze the impact of pruning and thinning measures on the combustibility of the surface combustible fuels such as moisture, ash, crude fat, burning point, and calorific etc. The results showed that after nurturing, the height below the branches of the Pinus armandii forest increased to 6.3~8.5 m, the forest contains 1 900~2 700 trees per hectare, the moisture was below 15%, the ash contents were 2.94%~5.58%, the crude fat contents were 7.94%~8.09%, the ignition point was around 270 ℃, and the calorific value was 20 020~21 084 kJ/kg. In indoor simulated combustion, the ignition speed of combustible fuels did not exceed 2 s, the flame temperature was 462.0~475.8 ℃, and the flame radiation was between 6~7 kW/m2. The moisture of the surface combustible fuels decreased after nurturing, which was beneficial for seedling growth. And the height below the branches in the forest increased while the height of the surface flame was 0.45~0.51 m. Accordingly, after nurturing, the surface combustible fuels in the Pinus armandii forest features low moisture and load, moderate ash and crude fat content, high burning point and calorific. At the same time, the nurture measures can prevent surface fires from developing into canopy fires and effectively reduce the risk of forest fires. The results are conducive to the adoption of more reasonable measures by the local area, thus achieving scientific fire management.

This work introduced the fire risk, the characteristics of fire and explosion accidents and the key points of fire truck selection in hazardous chemical enterprises such as petrochemical enterprises, coal chemical enterprises, fine chemical enterprises, oil (storage) depot, petroleum and natural gas enterprises, and summarized the relevant laws and regulations, departmental rules and documents, national codes for the construction of full-time fire brigades (stations) in hazardous chemical enterprises in China. From the aspects of law, regulation and standard system, employment mode, occupational treatment, equipment and skill training, the problems existing in the construction of full-time fire brigades (stations) in hazardous enterprises in China were analyzed. Focusing on the goals of improving the system of regulations and standards, establishing evaluation methods and mechanisms, innovating employment modes, improving comprehensive support capabilities, optimizing equipment allocation, and strengthening vocational skills training, we put forward suggestions on the construction of full-time fire brigades (stations) in hazardous enterprises in China.

Based on the case of a 100 000 m³ light oil storage tank external floating roof sinking in a chemical storage enterprise in Gulei Economic Development Zone, Zhangzhou City, Fujian Province, this article provides a detailed review of the emergency accident and fire emergency response process of the fully sunk tank. Utilizing the advantages of carbon dioxide in fire extinguishing, the article introduces the process of using carbon dioxide injection for inerting emergency response, analyzes the main risks, challenges, and considerations faced in the disposal of such accidents, and provides work inspiration and measures suggestions for the disposal of similar accidents.

The wooden arch covered bridge is a bridge style that originated in the Northern Song Dynasty. Due to the particularity of its structure, in the years of exposure to the sun and rain, the wood is corroded, carbonized and loosened, and the fire risk is constantly increasing. Through on-site inspection and evidence collection, video image analysis and simulation restoration experiments of a wooden arch covered bridge fire, this paper analyzes the entire process of the wooden arch covered bridge from smoldering to ignition and disaster, finds out the cause of the fire accident, and puts forward corresponding preventive countermeasures and suggestions, providing reference for the investigation and determination of fire accidents in cultural relics and ancient buildings.

This study investigated a typical benzene tank explosion incident in a benzene tank caused by stray welding currents. Through on-site inspection, video surveillance, interviews, potential ignition source exclusion, and simulated on-site tests, it was determined that the fire was caused by stray welding currents. The fire risk from stray welding currents is often overlooked due to its concealed pathways and the specialized knowledge required for its recognition. Analyzing the mechanism of stray current generation in welding shows that the existence of multiple current paths is a necessary condition for the generation of stray currents, and the fundamental reasons for the stray currents exceeding the safety values are the aging of welding machine components, poor contact of current paths, improper positioning of welding clamps, and welding cable specifications and parameters not meeting the requirements, resulting in excessive normal path resistance. A fault tree for the benzene tank explosion caused by stray welding currents was established, analyzing the influencing factors of the explosion from three aspects: reaching the explosive limit concentration of mixed gases, stray welding currents exceeding safety values, and electrode discharge or overheating of the medium. Specific measures to prevent similar fires are then proposed to provide references for the safety management of welding.