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15 July 2021, Volume 40 Issue 7 Previous Issue    Next Issue

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Experimental study on thermal spread of Lithium Titanate battery under different heat dissipation designs YUAN De-qiang, LIU Jin-zhu, ZHANG Wen-zhong, WANG Zhan-guo, HUANG Wei-nan 2021, 40 (7):  955-958.  Abstract ( 1756 )   How to prevent thermal runaway and thermal spread effectively is important in the design of lithium-ion battery modules. In order to explore the control ability of different heat dissipation design on the thermal spread of lithium-ion battery module, taking lithium titanate battery modules as the experimental object, the thermal spread blocking ability of natural convection, surface liquid cooling, and tab forced air cooling were studied. Through comparison, it is found that the key to suppressing thermal spread effectively is to increase the resistance of the spreading path and improve the heat dissipation capacity. The blocking method of surface cooling is more direct, which can block thermal spread, and the effect is far better than that of tab cooling. Related Articles | Metrics

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Study on the characteristics of gas deflagration caused by the thermal runaway of Lithium-ion battery KAN Qiang, CHEN Man, REN Chang-xing 2021, 40 (7):  959-962.  Abstract ( 1790 )   This work experimentally studied the risk of the gas deflagration and the fire caused by the Lithium- ion battery in case that the thermal runaway happens in an energy storage system. Besides, the risk of the electrolyte under high temperature and the thermal runaway properties of the Lithium ion battery are also investigated. The results indicate that the gases caused by the thermal runaway of the lithium- ion battery performs a high deflagration level, and the lower explosive limit is about 6.1% . The maximum explosive pressure reaches to 0.61~0.76 MPa, which can cause severe damage to the building structure. Besides, the minimum ignition energy of the gases caused by the thermal runaway of the Lithium ion battery is only 0.3 mJ. The releasing gases of the electrolyte under 120~130 ℃ have a lower explosive limit of 2.3%, showing a high risk, which can also lead secondary damage to the human. It is shown that the activation temperature of the thermal runaway of the Lithiumion is between 125~150 ℃ . The experimental results can provide guidance for the detection of the flammable gases and the design of the ventilation system in energy storage system. Related Articles | Metrics

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A review of the safety characteristics of lithiumion batteries after impact extrusion#br# HAO Xin, DU Jian-hua, LIANG Hao-bin, YANG Shi-zhi, TU Ran, ZHANG Ren-cheng, 2021, 40 (7):  963-967.  Abstract ( 1755 )   The relevant research on the safety characteristics of lithium- ion batteries after impact extrusion was summarized from both experimental and simulation perspectives at home and abroad in recent years, and the four influencing factors as punch shape, mechanical loading method, mechanical loading position, and SOC state was analyzed. The analysis results showed that the larger the internal short-circuit area of the lithium-ion battery, the more marginal the impact extrusion position and the higher the SOC, the higher the temperature at failure, the faster the voltage drop and the easier the thermal runaway; and the larger the strain of the lithium- ion battery, the smaller the internal resistance. According to the change law of the voltage, temperature, internal resistance and other safety characteristics parameters of lithium battery before thermal runaway by impact extrusion, an early warning identification method of lithium battery safety status is established, which is extremely necessary to prevent thermal runaway safety accidents caused by impact extrusion of new energy vehicles. Related Articles | Metrics

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Study on improvement of heat-resisting capacity of pipe of the transformer fire extinguishing system CHEN Bao-hui, ZHOU Tian-nian, WU Chuan-ping, LIU Yu, FANG Lu-jun 2021, 40 (7):  968-970.  Abstract ( 1723 )   According to the requirement of heat-resisting properties of fire pipe of fire extinguishing system used for protecting transformers, an experimental platform was set up. Burn resistance experiments in 3 min and 6 min of fire pipe and clamp was carried out. The burn resistance of the fire clamp made of EPDM rubber and fluorosilicone rubber was compared. The effect of fire- retardant coating on the burn resistance of fire pipe and clamp of transformers fire extinguishing system was evaluated. A strategy to improve the burn resistance of fire pipe and clamp of transformer fire extinguishing system was put forward. It guided the reliable extinguishment of transformer fires, and provided reference for renovation and construction of transformer fire extinguishing system. Related Articles | Metrics

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Study on the leak and diffusion law of gas in residential buildings WU Xian, YAN Ji-ming, LIANG Guo-fu, LU Zhi-bao, WANG Xin, CHEN Li, CAI Hao, WANG Yue, WANG Yuan-yuan, MAO Yuan-chao 2021, 40 (7):  971-976.  Abstract ( 1739 )   Through constructing a large- size experiment platform for gas explosion, the distribution and diffusion of gas leakage within the residential buildings were stimulated. By collecting data by the mobile and fixed sensors, the changes of gas leakage concentration in different positions over time were collected and the laws of gas leakage diffusion in buildings were summarized. Meanwhile, by building a concentration map, the changes of gas concentration in the kitchen at different moments after gas leakage were presented. Related Articles | Metrics

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Study on optimization of ventilation efficiency about jet fan in curved tunnel CHEN Yan, WANG Tian-xiong, TAO Hao-wen, XU Zhi-sheng 2021, 40 (7):  977-982.  Abstract ( 1699 )   Based on the underground interchange project of Jianning West Road, CFD software was used to simulate the horizontal spacing and arrangement position of the jet fans in the curved tunnel, the deflection angle of the fans, the longitudinal spacing, then the flow field distribution and jet fans booster capacity under different cases were analyzed. The results showed that in a curved tunnel, when the lateral spacing of the jet fan is twice the diameter of the fan, and it is close to the convex surface of the tunnel and deflected by 5° to 10° toward the concave area, the downstream flow field distribution of the fan is relatively uniform, and the tunnel ventilation effect is good. The longitudinal spacing of jet fans should not be greater than 100 m. Related Articles | Metrics

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Pyrolysis characteristics and kinetic analysis of waste bamboo flooring XUE Wei, LI Qi 2021, 40 (7):  983-986.  Abstract ( 1590 )   In order to study the pyrolysis characteristics of waste bamboo flooring, the pyrolysis experiments of waste bamboo flooring particles were carried out by thermogravimetry. The pyrolysis parameters and thermogravimetry curves of waste bamboo flooring particles under different particle sizes, heating rates and atmospheres obtained by using the control variable method. The Coats were Redfern integral method was used for thermokinetic analysis, and the optimal mechanism function was selected. The results show that the pyrolysis of waste bamboo flooring can be divided into four stages, and the temperature range of each stage is about 20～100 ℃ , 100～200 ℃ , 200～384 ℃ and 384～800 ℃ respectively. Through the study of pyrolysis conditions, the particle size can affect the main weight loss stage of pyrolysis, which will delay the occurrence of this stage. The effect of heating rate on pyrolysis is mainly reflected in the third stage. The larger the heating rate is, the more intense the reaction is. Air can promote the pyrolysis, which can make the reaction more sufficient and the weight loss greater. Related Articles | Metrics

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Study on fire behavior of cable cabins in utility tunnel under low oxygen concentration LIU Xin, ZHU Guo-qing, XU Gang, 2021, 40 (7):  987-990.  Abstract ( 1618 )   In order to study the fire behavior of the cable cabins of the utility tunnel under low oxygen concentration, a low oxygen environment was formed by injecting liquid nitrogen. The cables were arranged at locations 0, 30 and 60 cm away from the center to carry out the scaled tube gallery test, and the test was compared with that under normal oxygen concentration.It is found that at low oxygen concentration, the flame area decreases, and the flame bending degree decreases when the fire source is near the side wall. After dimensionless treatment, the longitudinal temperature was fitted, and the empirical formula of longitudinal temperature attenuation at two oxygen concentrations was obtained. The maximum temperature in the transverse direction is near the ceiling position above the flame. The maximum temperature in the low oxygen concentration is lower than that under the normal oxygen concentration. When the fire source is near the side wall, the temperature difference increases due to the influence of the flame temperature. Related Articles | Metrics

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Experimental study on the smoke properties under longitudinal ventilation in a tunnel with vertical shafts ZHU Li-ying, GUO Qing-hua 2021, 40 (7):  990-994.  Abstract ( 1611 )   This paper experimentally studied the influence of the longitudinal ventilation on the smoke exhaust performance of the vertical shaft and the ceiling temperature distribution. HRR and longitudinal ventilation velocity were considered during the fire tests. The results show that ventilation velocity has an impact on HRRs of heptane. For small square pool fires (≤11 cm) , HRRs keep approximately constant regardless of the ventilation velocities while for relatively large square pool fires (≥14 cm), HRRs decrease initially and then keep approximately unchanged with the increase of the ventilation velocities. Besides, when the ventilation velocities in the tunnel are low, the smoke is exhausted from the shaft by adhering the shaft sidewalls, and the smoke temperature on the downstream side of the shaft is low, indicating a good exhaust performance. When the ventilation velocity in the tunnel is high, the boundary separation in the shaft occurs and the smoke temperature downstream the shaft is high, and the smoke moves further, indicating a low smoke exhaust efficiency of the shaft. Therefore, it is suggested that in a naturally ventilated tunnel fire, low velocity can be employed, but the high ventilation velocity should be avoided. Related Articles | Metrics

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Numerical simulation of high temperature mechanical properties of reinforced concrete frame structure under fire LIU Meng, QIU Yuan, LI Meng-jie, WEN Kai 2021, 40 (7):  995-998.  Abstract ( 1672 )   A single layer double span reinforced concrete frame model was established. Based on the thermal performance and high temperature mechanical properties of steel and concrete materials, and using ABAQUS finite element software, the single compartment fire and multi-compartment fire were simulated. The temperature field distribution characteristics and change law of internal force and deformation of beam and column members andwhole structure were studied under different conditions. Results showed that under the two different fire cases of the single span and double span of the fire, the temperature field of the double span beam and side column under fire is the same as that of single span under fire, and the temperature distribution of the central column and the joint core area is different. The temperature of the joint core area is obviously lower than that of the surrounding beam and column. The fire mode and axial compression ratio of frame column plays a significant role in high temperature mechanics response of frame structure. Related Articles | Metrics

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Optimization of indoor evacuation path based on improved ant colony algorithm ZHAO Li-cai, 2021, 40 (7):  999-1003.  Abstract ( 1682 )   Against the defect of using traditional ant colony algorithm to solve the problem of indoor evacuation, such as slow convergence, and local optimum, the dynamic parameters of fire field are introduced into the ant colony algorithm, and the path selection strategy, heuristic function and pheromone updating strategy are improved to find the better evacuation path for the whole evacuation group. The improved ant colony algorithm is used to dynamically plan the evacuation path of indoor personnel, considering the real- time congestion degree of the path, avoiding the bottleneck effect of local route optimization of evacuation personnel. The analysis results are compared with the planning results of basic ant colony algorithm. The research results show that the optimization algorithm shortens the evacuation time and planning path, and improves the evacuation efficiency and search speed. Related Articles | Metrics

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Fire risk analysis and countermeasures of an underground wholesale shopping mall MA Zi-chao, YAN Chao, MA Jun 2021, 40 (7):  1004-1008.  Abstract ( 1764 )   In order to study the fire risk of underground wholesale shopping malls,an underground wholesale shopping mall was selected as the research object. Through the investigation of the field data, three typical fire scenarios were set, including shop fire, stairwell fire and walkway fire. The fire model was established by FDS, and the smoke flow in the underground wholesale mall was analyzed. According to the fire risk standard, the dangerous time in different areas was determined. Based on this,the evacuation simulation was carried out by Pathfinder evacuation software. The results showed that people in the underground wholesale mall can't evacuate safely in case of fire. Combined with the present situation and simulation situation of the mall, the safety hazard is rectified to ensure the safe evacuation of people in case of fire,and the fire prevention and control measures are put forward. Related Articles | Metrics

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Simulation study on fire pressure characteristics of mountain tunnel under chimney effect JIANG Hao-kai, LI Zhi-sheng, CAI Xin, ZHANG Yu-chun, KONG Xiang-sui 2021, 40 (7):  1009-1012.  Abstract ( 1633 )   In order to explore the variation characteristics of fire pressure in the shaft during mountain tunnel fire，numerical simulation method (FDS) is used to research the flow characteristics of smoke when the fire source is near the shaft or away from the shaft，and analyze fire pressure's variation law in the shaft under longitudinal ventilation. The results showed that，due to the influence of flue gas vortex，the fire pressure in the shaft shows a non-monotonic tendency，which is different from the traditional slope tunnel fire. Thus the theoretical model of tunnel fire pressure can't be used to predict the fire pressure in the shaft directly. With the longitudinal wind speed from 0 m/s to 3.5 m/s，the fire pressure in the shaft increases gradually，and the maximum difference is about 40 Pa. When the fire source is near the shaft，the fire pressure in the shaft is higher than that is away from the shaft. When there is without longitudinal wind，the maximum difference is about 25 Pa. Related Articles | Metrics

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Numerical simulation of natural gas leakage and diffusion in residence space under multiple factors ZHU Jing, QI Yuan-lei, XIN Pei-gang, XU Chun-wen, ZHANG Jiao 2021, 40 (7):  1013-1016.  Abstract ( 1661 )   Accidental leakage of natural gas in residential space can cause significant harm to residents. In this paper, CFD simulation is used to analyze the diffusion law, the explosion area and influencing factors of natural gas leakage in typical residential environment and the role of natural ventilation in reducing the risk of explosion is evaluated. In addition, the simulation results are verified by experiments. The simulation results show that flammable clouds accumulate in the upper part of the space and spread to adjacent rooms. Natural ventilation is an effective way to prevent natural gas accumulation and to reduce the risk of leakage. Related Articles | Metrics

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Research on combustion risk analysis of typical floor decoration materials in metro compartment DUAN Jia-hao, YANG Ling, SHI Cong-ling, LI Jian 2021, 40 (7):  1017-1019.  Abstract ( 1649 )   In order to carry out all- round characterization and analysis of the characteristics of typical floor decoration materials in metro compartment, cone calorimeter is used to measure the heat release rate, total heat release, CO and CO2 release rate, and total smoke release rate during the material combustion process. The material is pyrolyzed under programmed temperature control by a thermogravimetry- infrared combined instrument, and the infrared absorption spectra of the material pyrolysis process at different temperatures are obtained. A field emission scanning electron microscope is used to characterize the morphology and structure of the residue after the material is burnt. Experimental results indicate that the material forms a flame-retardant carbon layer structure during the combustion process, which plays a role of heat insulation and oxygen insulation within a certain period of time, and delays the combustion reaction; the material burns completely within 8 minutes. Once a fire occurs, the heat hazard and smoke hazard are greater; The pyrolysis process can be divided into 4 stages; the material starts to decompose at 350 °C and reaches the peak of pyrolysis at 440 °C, producing a large amount of H2O, CH4 and aromatic compounds. Related Articles | Metrics

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Traffic volume forecast and evacuation capacity assessment of subway station in the city rapid developing JIA Tian-yao, CHENG Guang-mou, ZHANG Bo, SUN Chun-guang, XU Xiao-ling 2021, 40 (7):  1020-1023.  Abstract ( 1694 )   A grey prediction GM( 1,1) model is established based on grey system theory, and the traffic volume of a existing subway station in a city which has a fast development and high growth rate of population is predicted. The result shows that, the maximum cross- section traffic volume during peak hours of subway station in the city which has a rapid growth of urban population will reach its long- term design stage forecast peak hour traffic volume ahead of schedule about 14 years, and will exceed 18.58% of its long- term design stage forecast peak hours traffic volume 10 years after it was put into service. Then the evacuation capacity of subway station under different traffic volume intensity is simulated, the result indicates that when the subway traffic volume is bigger than 10.88% of its maximum design traffic volume, the time for all personnel to evacuate to safety zone will exceed 6 minutes, which means the evacuation capacity of the station will no longer meet the requirements of the current specifications. Related Articles | Metrics

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Analysis of influencing factors in emergency decision of leakage accident in sour gas well station LIAO Kai, LIANG Kai-wu, JIANG Feng, WANG Li-jing, CHEN Xing-yu, WANG Wen-he 2021, 40 (7):  1024-1027.  Abstract ( 1653 )   After the leakage accident of a sour gas well station, how to make scientific and effective emergency decision is one of the practical problems faced by the government and enterprises. In this paper, 18 factors affecting the emergency decisionmaking of leakage accidents in sour gas well stations are screened out, and a six- level hierarchical structure is established by Interpretive Structural Modelling (ISM). On this basis, the interrelation among various factors is deeply analyzed, and the factors are classified. Relevant decision-making improvement measures are put forward. The results show that the Interpretive Structural Modelling- Matriced'Impacts Croises- Multiplication Appliance Classement (ISM-MICMAC) reveals the influence of many factors on the emergency decision-making of leakage accident in sour gas well stations, and can provide necessary decision-making support for emergency rescue. Related Articles | Metrics

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Simulation analysis of small hole leakage accident in high consequence area of natural gas pipeline based on system dynamics WU Dong-rong, XU Duo, ZHU Jian-ping, JIANG Yi, YANG Chuan, CHEN Li-qiong 2021, 40 (7):  1028-1033.  Abstract ( 1623 )   Based on the characteristics of natural gas pipeline leakage accident, small hole leakage rate model and accident injury model of natural gas pipeline, a system dynamics model was established according to the actual working conditions and personnel distribution characteristics of specific high consequence area to study the dynamic analysis of accident consequences with the intervention of emergency response time change. Meanwhile, the calculation model of personnel death coefficient was established, and Vensim- PLE software was applied to carry out the simulation analysis for the specific high consequence area, and obtained the leakage rate, leakage volume and its change trend with time under different leakage aperture, as well as the change rule of personnel death toll and comprehensive death toll of different evolution accidents with occurrence time. Through the adjustment of the emergency response time parameters, the shortest emergency time to achieve zero death for the small hole leakage accident in the high consequence area was finally obtained, which provided scientific decision support for the safety management in the high consequence area. Related Articles | Metrics

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Consequence assessment of UHV transformer vapor cloud explosion based on FLACS ZHANG Shao-hua, JIANG Hui-ling, LIU Guo-ping 2021, 40 (7):  1033-1037.  Abstract ( 1737 )   Against the problem of steam cloud explosion accident caused by UHV transformer fire, combined with an UHV transformer deflagration accident, a full-scale UHV transformer model was established using FLACS to simulate two working conditions: the first steam cloud explosion of the transformer and the explosion after the steam cloud fully expanded, and the explosion damage range was decided. It is found that the maximum pressure of the first steam cloud explosion is 7.2 kPa, which is concentrated on the upper part of the oil tank and mainly destroys the upper structure of the oil tank. For the second steam cloud explosion, the maximum pressure is 26.7 kPa, and the pressure is concentrated around the entire transformer, and the transformer is destroyed as a whole. According to the result of explosion simulation, the automatic fire extinguishing system can be reasonably arranged and the damage to the automatic fire extinguishing system can be reduced. Related Articles | Metrics

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Fire resistance improvement measures research for water spray fire protection pipe network of UHV transformers QIU Ning, ZHANG Jia-qing, WANG Hui, GUO Yi, LI Guo-hui, XIE Jia, LIU Rui, 2021, 40 (7):  1038-1042.  Abstract ( 1690 )   The integrity of the stock fixed extinguishing system of the UHV substation is an important prerequisite to realize its extinguishing ability. First, the fire resistance status of fire pipe network of water spray extinguishing system for the UHV sub station is defined by comparing fire resistance test methods of fire pipe specified in existing standards and combining with true fire extinguishing test data of UHV transformer. Secondly, the principle of gas burner is used to design the test ignition source. The temperature of the test ignition source is in good agreement with the temperature measured in the fire extinguishing test of the full- size UHV transformer model. Therefore, using the test ignition source to carry out the fire resistant test can be more in line with the actual possible heating situation. Finally, through the comparative test, some suggestions to improve the fire resistance of water spray fire pipe network are proposed, which can provide reference for the actual engineering reconstruction and construction. Related Articles | Metrics

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Discussion on the applicability of various fire Extinguishing modes in utility tunnel WANG Chen, FANG Zheng, TANG Zhi, 2021, 40 (7):  1042-1045.  Abstract ( 1664 )   The advantages and disadvantages of various automatic fire extinguishing methods, such as water spray, water mist, gas fire extinguishing,aerosol, super fine dry powder system and local application mode, were compared systematically. The application conditions and scope of each system were discussed, and some application cases of fire-extinguishing system used in some utility tunnel projects in China were introduced. At the same time, it is proposed that the general branch or the imperfect pipe tunnel can be constructed step by step according to its economic conditions, and the manual, semi fixed or local fire extinguishing system should be set up first, and then further upgrading should be carried out when the conditions are met. Related Articles | Metrics

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Experimental study on suppression of methane-coal dust compound explosion by ultra-fine water mist CHEN Biao, FENG Xiao, ZHANG Hao-tian, WU Zhong-yi, CHAI Yu-xuan, REN Jing-jie, BI Ming-shu 2021, 40 (7):  1046-1051.  Abstract ( 1703 )   The suppression effect of ultra-fine water mist on methane-coal dust compound explosions was systematically studied in a confined space dust apparatus. Flame propagation velocities, explosion overpressure, pressure rising rate were measured owing to the suppression effect of variously concentrations of ultra-fine water mist. The mechanism of explosion suppression and the behaviors of flame propagation after the addition of ultra- fine water mist were further investigated. Moreover, the critical mist concentration of suppression was decided under different particle sizes and concentrations of coal dust. The results show that the ultra- fine water mist delays the start of the explosion overpressure significantly. Flame experiences four development stages: point flame, partial powerful flame, continuous non- smooth flame and stable layered flame. Therefore, inhibiting the appearance of partial powerful flame is the key reason for suppressing explosion. As the concentration of ultra-fine water mist increases, the secondary accelerating rise of the overpressure disappears gradually, and the correlation between the heat release rate of the explosion and the combustion rate of the flame front is enhanced. The critical mist concentration first increases and then decreases with the increase of coal dust concentration, and decreases with the increase of coal dust particles size. Related Articles | Metrics

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Influence of hydrant arrangement and switching state on flow and pressure drop SHANG Bi-chen, ZHAO Ling-ling, SHU Xue-ming 2021, 40 (7):  1052-1055.  Abstract ( 1690 )   We use the numerical simulation method to study the pressure drop and flow characteristics of outdoor fire hydrant under different outlet switch states, and the flow characteristics of multiple fire hydrants with different spacing in the pipeline are calculated. The results show that the flow rate of about 19% of the fluid at the fire hydrant outlet is much lower than the average flow rate, which cannot be sprayed to the designated firefighting point; opening more than one switch will cause the pressure reduced by 58.3%~85.7%, and flow reduced by 28.3%~62.7%, which will harm the high- rise building firefighting and long distance firefighting; when multiple hydrants are opened, the flow of single fire hydrant is reduced by 13.5%~33.8%, and the total flow is reduced by 14.6%~27.0%; besides, with the increase of fire hydrant spacing from 10 m to 120 m, the flow of fire hydrants in the middle and lower reaches will be gradually reduced. The study can provide guidance for the installation and use of fire hydrants Related Articles | Metrics

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Research status of cryogenic hydrogen release and propagation characteristic of jet fire GONG Liang, JIN Kai-yan, YANG Sheng-nan, ZHANG Yu-chun, YANG Xiao-long, LI Zhi-sheng 2021, 40 (7):  1056-1060.  Abstract ( 1771 )   The application prospect and risk of leakage are elaborated. The research status on gas diffusion characteristic and jet fire ignition and propagation behavior of cryogenic hydrogen release is reported. The methods and conclusions on gas diffusion and jet flame of cryogenic hydrogen release are summarized and analyzed. The methods include experimental investigation and numerical simulation. Most of the researches focus on the gas diffusion characteristic. The conditions and influencing factors of the ignition and propagation behavior of the jet flame are not yet fully understood. In the future, the prediction model of gas diffusion characteristic during cryogenic hydrogen release should be developed, and the mechanism and influencing factors of cryogenic hydrogen ignition and jet flame propagation behavior should be further studied to establish an effective prediction model on gas diffusion characteristic and jet flame propagation behavior of cryogenic hydrogen release. Related Articles | Metrics

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Progress in research and application of phosphorous flame retardants in transparent fire-retardant coatings HU Xiao, YAN Long, HUANG Ao, ZHAO Min, WANG Xue-bao, SUN Jun-li, WANG Ji 2021, 40 (7):  1061-1064.  Abstract ( 1744 )   Wood-based structure has low fire resistance levels and large fire loads. Once a fire occurs, it will cause serious fire accidents. Transparent fire-retardant coatings are widely used to enhance the fire safety of ancient buildings due to their excellent decorative properties and fire resistance properties. Phosphorus-based flame retardants are widely applied as the main component of transparent fire- retardant coatings due to the advantages of environmental friendliness, high efficiency, low toxicity, etc.. This paper summarizes the research progress of phosphorus-based flame retardants in transparent fire-retardant coatings from the aspects of phosphate ester flame retardants, phosphorus-nitrogen flame retardants and composite phosphorus flame retardant. Research pointed out that the development of multifunctional modified phosphorus flame retardants, the realization of three sources in one, organic and inorganic phosphorus flame retardants, and the synergistic flame retardancy of multiple elements are the development trend of transparent fireretardant coatings in the future. Related Articles | Metrics

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Effect of ceramic fillers on properties of ethylene-propylene-diene monomer rubber composites ZHAO Xue-bai, XUE Lei, YANG Jin-jun 2021, 40 (7):  1065-1067.  Abstract ( 1596 )   The ceramifiable EPDM composite was prepared using glass powder, mica powder and montmorillonite as ceramic filler. The effects of ceramic fillers on the structure and properties of composites and their sintered ceramics were investigated by means of limiting oxygen index, vertical combustion, electronic universal testing machine and scanning electron microscope. The results show that the ceramic filler can improve the flame retardant and mechanical properties of the composite to a certain extent. Moreover, the content of the glass powder and sintering temperature can effectively improve the integrity and mechanical properties of the ceramic. Related Articles | Metrics

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Effect of particle size of aluminium hydroxide flame retardant on properties of asphalt HUANG Ya-dong, LIN Cheng-hang, JIANG Hao-jia, WU Ke, ZHU Kai 2021, 40 (7):  1068-1071.  Abstract ( 1677 )   The modified asphalt was prepared by using aluminum hydroxide (ATH) with four particle sizes of 1 μm, 6.5 μm, 25 μm, and 45 μm.The influence of ATH particle size on the flame retardant effect and thermal oxidation decomposition temperature zone of asphalt is studied by limiting oxygen index and thermogravimetric analysis. The penetration and softening point tests are used to study the influence of ATH particle size on the basic performance indexes of asphalt. The results show that when the flame retardant content is 25%, in the range of 1~45 μm, the larger the particle size of ATH, the better the flame retardant effect of the asphalt. Among them, the 45 μmATH modified asphalt has the best flame retardant effect. The oxygen index value of asphalt can be increased to 28.5%; Thermogravimetric analysis results show that both 1 μmATH and 45 μmATH advance the thermal oxidation decomposition temperature zone of each stage of asphalt, and the first weight loss peak rate of 1 μmATH modified asphalt is obviously greater than 45 μmATH modified asphalt. At the same time, the penetration value of asphalt shows a downward trend with the increase of ATH particle size, and there is no obvious law of softening point. Related Articles | Metrics

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The effect of graphene nanoplatelets on thermal stability and combustion properties of epoxy resin LIU Quan-yi, ZHAO Yin-long, GAO Shan-song, ZHI Mao-yong, 2021, 40 (7):  1071-1073.  Abstract ( 1658 )   The effects of the thermal stability and combustion performance of special epoxy resin (AG-80/JD-919) with added graphene nanoplatelets (GNS) was studied. Firstly, GNS was incorporated into the epoxy resin through solution blending method. And then the thermal stability and flame retardant properties of the flame retardant epoxy resin were tested and analyzed by thermogravimetric analyzer (TGA) and cone calorimeter (CCT). The results showed that when the dosage of GNS was 6 wt%, the char residue of epoxy resin increased by 4.6%, and the peak heat release rate (pHRR) and total heat release (THR) decreased by 40.63% and 15.43%, respectively. Therefore, GNS can improve the thermal stability and flame retardant properties of epoxy resin, which is mainly related to the physical barrier effect of GNS in the thermal decomposition process of epoxy resin matrix. Related Articles | Metrics

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Relationship between Eupatoriumadenophorum stem flammability and soil available phosphorus content in central Yunnan LI Guo-hui, WANG Kun-lun, CHEN Hong-gang, MA Rui-jie, JIANG Ting, BAI Lei, LI Shi-you, 2021, 40 (7):  1074-1077.  Abstract ( 1628 )   There are a lot of phosphate resources in central Yunnan, at the same time, it is also the distribution area of Eupatoriumadenophorum and forest fire in Yunnan. It can provide a scientific basis for understanding the fire distribution characteristics in central Yunnan and reasonable choice combustible management and forest fire control methods by studied the relationship between the combustibility of Eupatoriumadenophorumstems and the soil available phosphorus content. And 23 batches of Eupatoriumadenophorumstems, which is from Anning city, Chengjiang county, Dongchuan district and so on, were selected as the research object, and determined the crude fat content, ash content, calorific value of the Eupatoriumadenophorumstems and the available phosphorus content of the root soil of Eupatoriumadenophorum. And calculated the combustibility index of Eupatoriumadenophorumstems by the crude fat content, ash content and calorific value, and analyzed the relationship between soil available phosphorus and crude fat content, ash content, calorific value, combustibility index. The research has shown that the ratios of crude fat content, calorific value and comprehensive index of combustibility positively correlated with soil available phosphorus content were 65.22%, 52.17%, and 56.52%, respectively, and the ratio of ash content negatively correlated with soil available phosphorus content was 60.87%. Andsoil available phosphorus content can increase the crude fat content and calorific value of Eupatoriumadenophorum stem to a certain extent, reduce its ash content, and increase the combustibility to a certain extent. Related Articles | Metrics

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Research on the influence factors of the fire behavior of needle and broad leaves combustible on Miaofeng Mountain CAO Meng, BAI Ye, GUO Zan-quan, LI Shuang, YANG Shao-bin 2021, 40 (7):  1078-1081.  Abstract ( 1585 )   To understand the influence factors of the fire behavior, we studied the fire behavior in Miaofeng Mountain based on the experimental fires. The results showed that: The significant influence of speed of propagation, fire line intensity and flame length was the wind speed and slope(P < 0.05). However, the influence of the fuel depth and the percentage of needles to speed of propagation, flame length and fire line intensity was relatively small, which did not reach a significant level (P >0.05), and the most significant influence was the wind speed in the four influence factors, When the wind speed is 4 m/s, the maximum spread rate, flame length and fire line intensity can reach 2.357 m/min, 67.329 cm and 119.622 kW/m. Related Articles | Metrics

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Flame characteristics of fourmain kinds of surface fuels in main forest types among Kunming City WANG Qiu-hua, ZHANG Wen-wen, MIAO Xiu-li, FANG Xiang-yang, YAN Xiang-xiang, LONG Teng-teng 2021, 40 (7):  1082-1085.  Abstract ( 1668 )   Through field investigation, sampling and measuring of surface fuel characteristics of four main forest types in Kunming, flame experiments were carried out in the laboratory to determine the ignition time, flame holding time, maximum height of flame, maximum temperature, flame colors and thermal radiation. The results shown that：（1）the fuel loads of Pinus armandii forest,Pinusyunnanensis forest, Quercusacutissima forest, and Cupressusfunebris forest are 3.37 kg/m2, 2.35 kg/m2, 2.24 kg/m2, and 1.47 kg/m2, respectively.（2）The colors of the flames are dull red and the ignition time of cypress and Quercusacutissima is 3 s, while that of Pinusyunnanensis and Pinusarmandii is 1 s, which should be easily ignited. The longest flame duration was 6.34 min for Pinusarmandii, 3.89 min for Quercusacutissima, 3.45 min for Pinusyunnanensis and 2.28 min for cypress. The maximum flame height of Quercusacutissima is 90cm, Pinusyunnanensis 70 cm, Pinusarmandii 50 cm and cypress 20 cm. The highest flame temperature of Pinusyunnanensis is 897.5 ℃ , cypress 877.5 ℃ , Quercusacutissima 657.5 ℃ , and Pinusarmandiiis 563.3 ℃ . The maximum flame depth of Quercusacutissima is 105 cm, Pinusyunnanensis 85 cm, Pinusarmandii 63 cm and cypress 35cm. The maximum thermal radiation of Quercusacutissima is 7.31 kW/m2, Pinusyunnanensis 6.92 kW/m2, Pinusarmandii 6.70 kW/m2 and cypress 3.18 kW/m2. The flame characteristics of surface fuel of four main forest types around Kunming are very obvious, which is worthy of further studying.The results of this research are helpful to better grasp the characteristics of surface fuel and heat release law of main forest types around Kunming, and to carry out fire prevention management more scientifically and reasonably. Related Articles | Metrics

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The study of correlation analysis between fire risk and social factors ZHANG Yan, WANG Zhe-liang, ZHANG Xin, WANG Zhan-wei, LI Jin 2021, 40 (7):  1086-1088.  Abstract ( 1636 )   In order to study the influence of social factors on fire risk, grey correlation analysis method was adopted to calculate the correlation between social indexes, such as GDP, population and education level, and fire risk based on the historical fire data. The study shows GDP was positively correlated with the number of fires.The number of fires in provinces was strongly correlated with GDP, nevertheless the number of fires in cities was moderately correlated with GDP. There was a strong correlation between the resident population and the number of fires in each province, but the correlation was weak in less devloped provinces. The education level was negatively correlated with the number of fires when the education level of residents was low. However, the education level was positively correlated with the number of fires when the education level was high. Related Articles | Metrics

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Discussion on the safety of firefighters in inland rapids waters rescue YE Zhi-yong 2021, 40 (7):  1089-1090.  Abstract ( 1715 )   As the "main force" and "national team" of emergency rescue, the fire rescue team undertakes the important responsibility of preventing and resolving major safety risks and dealing with all kinds of disasters and accidents. Among them, water rescue has gradually become one of its important tasks. This paper deeply analyzes the casualties and influencing factors of water rescue disposal in recent five years, combs the domestic and foreign experience and practices, and puts forward specific suggestions from four aspects according to the safety problems of rescue operations, so as to provide reference for rescue theory and practice. Related Articles | Metrics

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Numerical simulation of a death-causing fire accident in excavator parts warehouse CHEN Yi-lin, GAO Dian-ce, LIANG Dong, MO Shan-jun, 2021, 40 (7):  1091-1095.  Abstract ( 1629 )   According to the investigation of a death-causing fire in an excavator parts warehouse, FDS was used to carry out numerical simulation and reconstruction. The burning situation of combustibles in the model was compared with the on-site investigation pictures. The heat release rate, temperature and gas concentration in the model were obtained. Assuming that water sprinkler was used, the data were analyzed and compared. Simulation results showed that the burning situation of combustibles in the model agreed well with the results of the on-site investigation. The temperature and the volume fraction of CO in the toilet where the deceased was located reached dangerous values. As the result, the main causes of death could be the joint action of high temperature burning, smoke poisoning and suffocation. If water sprinkler were used, the temperature and the volume fraction of CO concentration would be effectively reduced. Related Articles | Metrics

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Extended investigation of a major casualties fire HE Run-mei 2021, 40 (7):  1096-1099.  Abstract ( 1691 )   Through the identification and extended investigation of a major casualties fire, this paper summarizes the site characteristics of this kind of fire, discusses the in-depth identification and cause analysis of similar electrical fire, summarizes the extended investigation, and makes suggestions on fire prevention from the perspective of industry supervision and territorial responsibility, which has a strong reference value for the identification and extended investigation of fire causes in other small places. Related Articles | Metrics

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Analysis of primary short circuit at the fire location and is unconcerned with fire cause SHAO Zheng-ya 2021, 40 (7):  1099-1101.  Abstract ( 1680 )   Evidence examination of primary short circuit expert conclusion at the fire location is a main link of fire cause identification. By specific cases, the primary short circuit at the fire location and is unconcerned with fire cause is discussed, including special space location circuit, old circuit and circuit under continuous power supply. The formation mechanism is summarized, to provide reference for fire investigation. Related Articles | Metrics

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Several misconception and countermeasure of a fire investigation DING Ke 2021, 40 (7):  1102-1105.  Abstract ( 1664 )   During the process of fire investigation of large-span steel structure factory, the investigator meets some mistakes when utilizing monitoring video to analyze and judge the mode of fire, in accordance with the position of operating handle of circuit breaker to analyse whether it powers up, using multimeter on and off gear to measure whether internal circuit breaker is turning on, and melted mark of aluminium cable whether electric cable is charged. This essay clarifies the process caused by corresponding error and analyses the reason of error from the angle of investigation and practice and put forward the countermeasure and suggestion of avoiding similar errors in the fire investigation. Related Articles | Metrics

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Discussion on disaster cause and fire fighting safety TAO Peng, WAN Ji-kang 2021, 40 (7):  1106-1108.  Abstract ( 1669 )   How to reduce the casualties of firefighters in the fire fighting and rescue work has become an in- depth research and exploration topic in the new era. Although the firefighting evaluation and summary can effectively avoid and reduce the casualties, compared with the investigation of disaster causes in the fire investigation, the disaster causing factors summarized by firefighting evaluation have obvious limitations. From the perspective of disaster causes investigation, this paper analyzes the operational safety of firefighters, which can provide action guidance for fire fighting and rescue. Related Articles | Metrics