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15 June 2021, Volume 40 Issue 6 Previous Issue    Next Issue

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Research on thermal runaway propagationsuppression tech nology of lithium titanate battery module DONG Hai-bin, YIN Guo-rui, AN Pu-chun, XIAN Xue-lei, YI Cheng-yi 2021, 40 (6):  779-782.  Abstract ( 1890 )   The thermal runaway characteristics of 20 Ah square lithium titanate battery under overcharge condition were studied, and the variation rules and parameters of temperature, voltage, gas composition and content of lithium titanate battery under 100% SOC condition were obtained. Experiments showed that the jet flame of lithium titanate battery is more severe after thermal runaway. In order to restrain the propagation of thermal runaway of lithium titanate battery in modules effectively, a solution of using perfluoroh exanone inhibitor to inert the use space of lithium titanate battery before thermal runaway wasproposed. Through the experiments, it is verified that the early release inhibitor can inhibit the thermal runaway expansion of the battery moduleeffectively, and the key technical parameters such as the release time and inerting concentration of the inhibitor were obtained. Related Articles | Metrics

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Preliminary study on fire risk of echelon use lithium iron phosphate square cell under overcharge ZHUO Ping, GAO Fei, LU Shi-chang, DING Yuan-sheng 2021, 40 (6):  783-786.  Abstract ( 1929 )   In order to master the occurrence and development law of echelon use lithium-ion battery fire, different overcharge methods and overcharge rates were used to charge the lithium iron phosphate square battery(25 Ah, SOH=80% ) in echelon,and the combustion and explosion characteristics of the battery were investigated. The test results show that when the battery safety valve is opened and the overcharge is stopped, the battery may only discharge smoke and there will be no fire. When the battery is overcharged continuously after the safety valve is opened, the echelon use battery may burn and explode with the charging rate is more than 0.5 C. With the increase of overcharge rate, the opening of safety valve and the time to reach peak temperature and voltage will occur ahead of time. Related Articles | Metrics

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Research on the thermal runaway characteristics of lithium titanate batteries under different trigger conditions XING Xue-bin, YUAN De-qiang, WANG Zhan-guo, HUANG Wei-nan, JIAN Bin-bin 2021, 40 (6):  787-792.  Abstract ( 1824 )   Two commercial lithium titanate batteries with different capacities and different packaging forms were taken as the research object, the experimental study of thermal runaway triggering was carried out by means of overcharging, acupuncture and heating. Through summary of the experimental results, it is found that for lithium titanate batteries, under the same current excitation, the heat generation during the overcharge period is more obvious. Piercing direction and battery packaging have greater impact on the triggering of thermal runaway. The time required for an overcharged battery to run away of heating under the same power is much shorter than that of a fully charged battery. Related Articles | Metrics

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Study on the impact of pressure and EC/PC/EMC mass ratio on the electrolyte combustion characteristics ZHENG Kai-hui, WANG Jian, CHEN Qin-pei, MENG Xiao-kai, LIU Chang-cheng, HUANG Que 2021, 40 (6):  793-797.  Abstract ( 1892 )   Investigating the fire hazard of electrolyte would be conducive to the quantitative evaluation of battery safety. In this paper, the impact of ambient pressure and mass ratio of carbonate solvents ethylene carbonate (EC)/propylene carbonate (PC)/ethyl methyl carbonate (EMC) on the parameters associated with combustion characteristics such as flame centerline temperature, mass loss rate, heat release rate for two kinds of electrolyte was studied and analyzed. The experimental results showed that the stable combustion stage of electrolyte was the main part during the whole combustion processing. The flame centerline temperature increased with the decrease of the pressure. The gain of PC content would improve the low- temperature performance of the electrolyte, while which would also lead to an increase in fire risk. Related Articles | Metrics

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Combustion characteristic of 20 species of lianas in Kunming area ZHANG Qiao-rong, TONG Yan-min, RUAN Zhi-chen, LI Guo-hui, WANG An-you, YU Shi-bo, WANG Tian-ping, LUO Shu-lin 2021, 40 (6):  797-800.  Abstract ( 1931 )   There are abundant species of lianas in the forests of Kunming, Yunnan province, China. In order to compare the combustibility differences of common species of lianas in this area, the 20 kinds of common lianas flammability test of fresh leaves sampled from living lianas was made by self- designed burning device based on the their investigation of biological and ecological characteristics, such as aboveground viability, habitat, etc. Meanwhile, leaf relative moisture content, mass per unit area, burning rate and degree of damage were measured and calculated. The result showed that 20 species of lianas were divided into 3 categories according to their different combustibility. The details are as follows: (1) Pomona purpurea, Zehneriamaysorensis, Dioscureamelmanophyma, Dinetusracemosus, D. hemsleyi, D. hemsleyiare flammable lianas. (2) Four species of lianasare combustible, and their combustibility from high to low ranked as follows: Dumasiavillosa>Smilaxferox>F. sarmentosa var. duclouxii>Jasminumofficinale. The last species of liana. (3) Holboellialatifolia, Ficustikoua, Smilaxmicrophylla, Dregeasinensis, Tetrastigmaobtectum, Senecioscandens, Sabiayunnanensis, Periplocaforrestii, Rubiapodanthare nonflammable lianas. The last species, Fallopiamultiflora, is combustible in the sunny habitat, but nonflammable in the shady habitat. The study indicates that combustibility of lianas is not only influenced by biological characteristics and habitat, but also related to leaf relative water content, mass per unit area of a leaf, leaf thickness, etc. It is recommended that F. tikoua could be used as a groundcover plant species to manage forest for fire prevention. Related Articles | Metrics

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Experimental investigation of the minimum ignition energy of HDPE dust cloud ZHENG Qiu-yu, LIU Lin, LIU Tian-qi, LIU Yi, HAN Rui 2021, 40 (6):  801-804.  Abstract ( 1751 )   In order to study the explosion sensitivity parameters of high density polyethylene (HDPE) dust cloud, experimental research on HDPE dust was carried out. The MIE of HDPE dust cloud was tested by the minimum ignition energy test device. Firstly, the effects of three single factors (dust particle size, dust cloud mass concentration and dispersion pressure) on MIE were studied, and then the flame propagation behavior of HDPE dust clouds with different mass concentrations burning in Hartmann tube under certain conditions was analyzed. Finally, orthogonal experiment method was used to analyze the influence of multiple factors on MIE. The experimental results showed that: with the increase of dust particle size from 25 μm to 120 μm, the MIE increases gradually; with the increase of HDPE dust cloud mass concentration, the MIE decreases and then slowly rises. The MIE decreases first and then increases when dispersion pressure increases from 50 kPa to 400 kPa. The greater the mass concentration, the stronger the degree of intense combustion in the Hartmann tube, and the longer the presence time of the explosion. The dust particle size had the most significant influence on MIE. Related Articles | Metrics

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Effect of rubber powder on the fracture properties of C60 HPC after high temperature FAN Qi, DU Hong-xiu, CHENG Cong-hui, SONG Jia-jia 2021, 40 (6):  805-808.  Abstract ( 1653 )   In order to study the effect of rubber powder on the fracture performance of C60 high performance concrete after high temperature, high temperature tests were carried out on C60 HPC with rubber powder content of 5% and 8% to determine the compressive strength and splitting tensile strength, and based on the double- K fracture theory, a three- point bending fracture test was performed on the specimen, the fracture parameters were calculated, and the initiation toughness and instability toughness were plotted against temperature. The results show that as the temperature increases, the compressive strength and splitting tensile strength of C60 HPC show a downward trend, and the addition of rubber powder will reduce the mechanical properties of C60 HPC. The initiation toughness and instability toughness of C60 HPC mixed with rubber powder at 400 ℃ decreased by 8.7% and 12.2%. At 400~600 ℃, the initiation toughness and instability toughness decreased by more than 50%. Analysis and fit curve shows that the thresholds for the initiation toughness and instability toughness loss of C60 HPC blended with rubber powder are 400 °C and 500 °C separately. Related Articles | Metrics

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The influence of ply structure on fire behavior of carbon/epoxy laminate CHEN Wen, XU Yan-ying, LI Jin-du, WANG Zhi, Meng Fan 2021, 40 (6):  809-812.  Abstract ( 1681 )   The cone calorimeter, vertical/horizontal burning test and limiting oxygen index test were used to study the influence of unidirectional and woven fabric ply structures on the fire behavior of carbon/epoxy laminate. The results show that with the increase of heat flux, the ignition time of carbon/epoxy laminates with different ply structures decreased, the mass residual rate reduced, the peak value of heat release rate and smoke production rate, the total heat release and total smoke release increased, and the time to peak decreased. Under the same heat flux, compared with the woven fabric ply structure, the carbon/epoxy laminate of unidirectional ply structure has longer ignition time, higher mass residual rate, heat release rate and smoke production peak value. The time to peak is shorter, the total heat release and total smoke release are lower. Besides, the flame spread speed of the woven fabric ply structure laminate is slow, and the influence of ply structure on the limiting oxygen index is small. Related Articles | Metrics

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Study on fire protection and key parameters of top centralized smoke exhaust shield tunnel structure ZI Yi, LU Zhi-peng, XUE Guang-qiao, GUO Chen-yang, XIE Bao-chao, XU Zhi-sheng 2021, 40 (6):  813-817.  Abstract ( 1728 )   Related Articles | Metrics

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Research on smoke control system of double storage line of an underground railway station RONG Jian-zhong, DENG Bao-shun, QIAO Xiao-bo, LIU Kai, HE Lei, XIE Yuan-yi, HUANG Xiao-lu 2021, 40 (6):  818-821.  Abstract ( 1710 )   In this paper, the cold smoke test was carried out on a subway double storage line in Chengdu. On the basis of the cold smoke test, the effectiveness of SES numerical simulation software was verified. Then, the hybrid numerical simulation of double storage line fire was carried out by using SES and FDS numerical simulation software, and the configuration scheme of smoke control system was obtained, which is at the optimal air supply and smoke exhaust air distribution mode of the double storage line. The research results have important engineering application value for the smoke control design of the complex subway line, especially the double storage line, and also can provide useful reference for the tunnel ventilation system configuration scheme design in the complex subway line. Related Articles | Metrics

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Evolution behaviors and properties of fires in power compartments in underground utility tunnels#br# LIU Hai-feng, LIU Jing-wen, SHEN Xue-liang, SUN Guo-cheng, LU Jian-feng, ZHOU Jian-xin, ZHENG Jing-rong, WANG Yun-long, YOU Fei, YU Yuan, ZHANG Peng 2021, 40 (6):  822-826.  Abstract ( 1712 )   In this paper, the main related research of urban underground utility tunnel and power compartment fires in China from 2017 to 2020 was reviewed, the research focus was summarized, fire evolution rules were discussed, and the future research directions were proposed. Related Articles | Metrics

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Artificial intelligence based facade spilled flame temperature field prediction JIANG Ya-qiang, WANG Zi-long, HUANG Xin-yan 2021, 40 (6):  827-830.  Abstract ( 1741 )   In order to clarify the influence of facade wing walls on spilled flame, an experimental study on the spilled flame under different facade wing wall conditions was conducted and the real- time prediction of the fire temperature field of the facade was predicted. The facade fire prediction database was constructed through facade fire experiments under different wingwall spacing and depth conditions, and applied to the training and validation of convolutional neural network (CNN), so as to establish a real-time prediction model for the flame temperature of spilled flame under different facade wing- wall conditions, and provide support for the design of facade construction forms and facade fire protection. Related Articles | Metrics

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Research on the effect of glass curtain wall breakage on indoor smoke extraction in super high rise buildings GAO Wei, REN Xiao-fei 2021, 40 (6):  831-837.  Abstract ( 1688 )   FDS software was used to analyze the indoor temperature, visibility, CO concentration and smoke spread law of a super-high-rise standard office floor under different smoke extraction modes and ambient wind when glass curtain wall rupture. The results show that: When the mechanical smoke exhaust is closed, the effects of indoor smoke extraction from high to low were broken glass curtain wall under no wind, unbroken glass curtain wall and broken glass curtain wall under wind; When the mechanical smoke extraction works, the effects of indoor smoke extraction from high to low were unbroken glass curtain wall, broken glass curtain wall without wind, and broken glass curtain wall under wind; When the mechanical smoke exhaust is closed, the broken glass curtain wall under no wind can be used as a natural smoke exhaust outlet, which is beneficial to indoor smoke exhaust; When the broken curtain wall is under wind, the environmental wind will restrain the smoke exhaust; When mechanical smoke extraction works, whether there is wind or no wind, the breakage of glass curtain wall will lead to the reduction of mechanical smoke extraction efficiency. Therefore, a safe and reliable mechanical smoke exhaust system should be set up in super high-rise buildings, and glass curtain walls with higher fire resistance should be selected. Related Articles | Metrics

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Experimental study on the influence of baggage weight on evacuation speed ZHANG Bo-si 2021, 40 (6):  837-842.  Abstract ( 1769 )   Taking college students as the examinee, based on the questionnaire survey results, the influence of baggageweight on the evacuation speed of pedestrians was investigated through experiments on people walking with baggage. The results show that: Under the heaviest weight of the backpack, handbag, messenger bag, the average evacuation speed of pedestrians decreases 6.0% , 3.6% and 4.2% compared with the no baggage condition. Based upon data fitting, the average evacuation speed of the pedestrians with backpack and messenger bag decreases linearly with the baggage weight, while the average evacuation speed of pedestrian with handbag decreases with the baggage weight exponentially. As the luggage case weight changes, the decrease trends of evacuation speed are different. Related Articles | Metrics

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Field test of super large water curtain system in exhibition hall CHEN Xu-hua, CHEN Qi-shuo 2021, 40 (6):  843-846.  Abstract ( 1733 )   The exhibition hall of Wuhan International Expo Center has a huge building volume. The fire separation water curtain of 80 m (width)×11 m (height) is used between the exhibition halls, which greatly exceeds the size limited by the current fire code. The effectiveness and reliability of the water curtain system in the exhibition hall can only be verified through field tests, so as to confirm whether the water curtain system can really play the role of fire separation. Through the field fire test, it can be concluded that the water curtain forms a complete and thick "water wall" between the exhibition halls, which effectively prevents the smoke from spreading to the adjacent exhibition halls. Related Articles | Metrics

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Study on fire spread model characteristics and forcasting of parallel double cables JIA Bo-yan, ZHANG Peng, WANG Tao, XU Ya-bing, ZHU Guo-qing, AN Wei-guang, 2021, 40 (6):  847-850.  Abstract ( 1685 )   Cables are widely used in urban buildings and industrial sites. Once the cable is ignited, it will cause serious consequences. The cable is not only one when laying, so this paper takes the parallel double cables in the horizontal direction as the research object. By analyzing the three thermal transfer modes in the combustion process, a mathematical model for predicting the flame spread rate is established. An experimental study on the flame spread of parallel double cables in the horizontal direction is carried out and the influence of cable spacing on flame spread characteristics are analyzed. The flame width and the flame height increased first and then decreased with the increasing of the cable distance, the flame spread rate also increased first and then decreased with the increasing of the cable spacing. The experimental results are in good agreement with the model prediction results. Related Articles | Metrics

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Simulation analysis of thermal radiation consequences of typical leakage fire in oil and hydrogen refueling station LIU Di, DANG Wen-yi, WANG Xi-ge, MAO Zhi-rui, ZHANG Jie-dong, 2021, 40 (6):  851-854.  Abstract ( 1855 )   According to the actual operation status of the oil and hydrogen refueling station, the typical fire accident scenarios are identified. The calculation models of high- pressure hydrogen leakage jet fire and oil leakage pool fire are established to simulate the typical fire hazard characteristics of ground hydrogen facilities and refueling equipment. The results show that the hazard range is large when the hydrogen jet fire occurs with 45 MPa leakage pressure and 10 mm typical leak aperture, and the damage distance to the equipment and personnel is 21 m and 36 m respectively. The impact distance of serious damage to the equipment is 5~8 m，and the impact distance of thermal radiation injury to personnel is 12~19 m when the refueling gun leakage of 40~60 L/min occurs. The research results can provide reference for layout optimization and safety management of oil and hydrogen refueling station. Related Articles | Metrics

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Numerical simulation study on fire development law of outdoor composite soft oil sac WANG Chun-hui, JIANG Xin-sheng, ZHANG Lin, YU Bin-bin, CAI Yun-xiong, WANG Zi-tuo, HE Dong-hai 2021, 40 (6):  855-860.  Abstract ( 1731 )   According to the combustion characteristics of oil fire, FLACS software was used to simulate the combustion process of small scale 0.5 m oil pool fire and the leakage and fire process of large scale field combined soft oil sac. The results show that: the distribution of maximum heat radiation flux of oil pool fire combustion is not strictly symmetrical with the central axis of oil pool. In the process of flowing fire combustion after oil leakage of the outdoor combined oil sac, the maximum radiation intensity received by the whole self- loading pallet is up to 35 kW/m2, and the maximum radiation intensity received by the oil sac is about 18 kW/m2. 20 seconds after the oil fire occurs, the thermal radiation intensity of the oil sac can reach the minimum energy for oil sac melting. Related Articles | Metrics

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The simulation calculation and analysis of the transient internal flow field of fire extinguishing bomb LI Yun-feng , DENG Kang-qing, LU Rui-hua 2021, 40 (6):  860-864.  Abstract ( 1746 )   In order to improve the accuracy of the simulation calculation of fire extinguishing bombs, the main factors that affect the simulation results: the burning rate model of the generator, the simplified model of the inlet condition and the firing judgment condition of the generator, are respectively calculated and analyzed in combination with measured data. Finally, a simulation calculation model for the transient process of fire extinguishing bombs with propellant as the driving source is established, which fits well with the experimental values.The simulation results show that the selection of the burning rate model mainly affects the slope of the pressure-time curve after the ignition pressure peak; the selection of the ignition gas model mainly affects the appearance time and intensity of the ignition pressure peak;the selection of ignition judgment model can make the curve move forward or backward in time as a whole. Related Articles | Metrics

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Simulation study on fire spread of traditional building community in Beijing Nanluoguxiang region XIAO Chun-bei, MA Jun, YANG Chen 2021, 40 (6):  865-869.  Abstract ( 1767 )   According to the multi-agent modeling method, the fire model was constructed, and combined with fire fighting activities, the fire process was simulated intuitively, which reflects the fire spread path and the fire control effect after setting up the micro-fire station.Taking the traditional building community area of Nanluoguxiang in Dongcheng District of Beijing as the research object, applying the simulation software NetLogo to model, four groups of different fire origins were set up for simulation, the fire spread paths under different circumstances were obtained, and the superposition analysis was conducted on the path to find out the region with the highest fire spread risk. Based on this, a quantitative strategy of micro- fire station layout was proposed to improve the fire response measures of traditional building communities. Related Articles | Metrics

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Simulation of emergency evacuation from underground assembly space LAN Zhen, DONG Shao-tang, KABILIJIANG·Wumair, ZHANG Dao-kang, LU Xin-xin 2021, 40 (6):  870-874.  Abstract ( 1726 )   In order to improve emergency evacuation capacity of densely populated underground space, under the background of coupling development of rail transit and underground space, through literature review and case analysis, investigation on evacuation risk identification and safety assessment is carried out. Using Anylogic platform, based on social force model and multi-agent modeling method, simulation and control group experiment are implemented. The experimental results show that the existing evacuation facilities of the station basically meet the 6- minute required evacuation time, where the evacuation starts when population is exceeding 1,800. It also reveals that pedestrian heterogeneity has a negative impact on the formation of evacuation bottleneck, and the zone evacuation strategy helps to alleviate the bottleneck pressure and reduce the risk of congestion as well. Related Articles | Metrics

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Research on fire and evacuation simulation of subway transfer station during peak period WU Jia-meng, ZHU Shun-bing, HAO Xue-tong, HAO Sheng 2021, 40 (6):  875-879.  Abstract ( 1763 )   In order to study the evacuation of people in a subway transfer station fire during peak period, taking JMS subway transfer station as the object, the building information model was established by Revit. Six kinds of fire scenarios were simulated by Pyrosim, and the failure critical values of all passing facilitieswere studied by taking the temperature, CO concentration and smoke visibility as safety indexes. The pedestrian parameters such as age, gender, weight and speed were added. The evacuation time, evacuation flow and evacuation bottleneck were discussed by Pathfinder. The results show that the evacuation fails under scenarios A2 and C2; Pedestrians are more inclined to pass facilities around during the escape process, leading to neglect of the best route; some facilities are idle when the evacuation bottleneck occurs in other passing facilities, which leads to the phenomenon of low utilization rate of facilities and low evacuation efficiency. Finally, optimization suggestions are put forward for the situation. Related Articles | Metrics

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Study on the effect of fire extinguishing system in cable compartment of utility tunnel TIAN Si-nan, LI Yan-feng, XU Chen-liang, YANG Quan, LIU Wen-bo 2021, 40 (6):  880-883.  Abstract ( 1713 )   In order to investigate the characteristics of cable fire and analyze the fire suppression effect of powder extinguishing system and high- pressure water mist system, a series of fullscale experiments and numerical simulations were conducted in the cable compartment of a practical utility tunnel project. A ethanol fire with HRR=0.7 MW was set under the bottom cable rack. The corresponding development of fire and the spread of smoke were observed to analyze the characteristics of cable fire in the cable compartment. By comparing the changes in temperature and smoke under two common-used fire suppression systems, the suppression effect of powder and high-pressure water mist systems were analyzed. Based on the full- scale experiments, the simulation software FDS was adopted to supplement and verify the results. Results indicate that after closing fire door of cable cabin, cable fire could not keep spreading, and the temperature stabilized between 600 ℃ and 700 ℃ . The powder extinguishing system had a quite short effective extinguishing time and a limited cooling effect. When the temperature above the fire source dropped to about 440 ℃ , cables began to reignite. By contrast, the water mist system could suppress fire for a consecutive and longer time and had a markedly positive influence on reducing temperature and suppressing the spread of smoke. Therefore, the water mist system could bring beneficial conditions for firefighters to enter the compartment and rescue. Related Articles | Metrics

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Study on the suppression mechanism of water mist on the deflagration of premixed methane gas in a barrier tube LI Zhuo-ran, XIA Yuan-chen, ZHANG Bin, YU Jia-hang, WANG Bo-qiao, CHEN Li, LIN Ye-jin 2021, 40 (6):  884-887.  Abstract ( 1707 )   In order to reveal the suppression effect of water mist on deflagration and the influence of the release position of water mist on the deflagration process of methane premixed gas, four types of water mist release positions and three particle sizes (8, 45, 80 μm) were designed. Results showed that，when the 8, 45，80 μm water mist was released at position 2, the pressure in the tube decreased by 36.59%, 65.85% and 31.7%, respectively. When position 3 is released, the pressure in the tube decreases by 34.15%, 56%, and 39.02%, respectively. 8 μm water mist has a significant inhibitory effect on the deflagration process, and has little effect on the flame structure and flame surface; 45 μm and 80 μm water mist have a significant impact on the flame structure and flame surface, and the flame surface appears wrinkled and divergently expands forward, and this effect becomes more obvious as the particle size of the water mist increases. The water mist mainly dilutes the premixed gas, reduces the local combustible gas concentration and vaporizes and absorbs heat on the flame. When the water mist is released above the obstacle closest to the ignition point and between two obstacles, the effect of suppressing deflagration in the tube is the most significant. Related Articles | Metrics

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Numerical simulation study of water mist fire extinguishing performance in cable shaft of hydropower station YE Hong, NING Xiao-yao, CHEN Qin-pei, LUO Yu-zhen, XU Zheng, JIN Xiang 2021, 40 (6):  888-891.  Abstract ( 1712 )   The cable shaft of a hydropower station is a vertical high-rise channel, up to 100 meters high, used for laying power supply cables or communication cables for a hydropower station. If it is not well sealed or not sealed, the fire will spread quickly along the cable shaft. Taking the cable shaft of a hydropower station as the research object and using FDS numerical simulation software, this paper studies the influence of four factors, including longitudinal distance of high pressure water mist nozzles, number of simultaneous starting floors, nozzle flow coefficient and spray angle, on the fire- extinguishing effect. The critical values of each factor are established to effectively play the role of fire extinguishing. The results can provide reference for the design of fire extinguishing system of cable shaft of hydropower station. Related Articles | Metrics

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Performance evaluation of earthquake relief equipment based on the utility function LI Chen, , PENG Wei-shi, WANG Nian-sheng, LI Qing 2021, 40 (6):  892-897.  Abstract ( 1671 )   For evaluating the performance of equipment for earthquake relief, and scientific ally planning of the equipment development, construct the index system of the performance evaluation of earthquake relief equipment basing on the goal of “Integration of on-war and off-war, versatile with strong capability, fast respond with high- efficient rescue”, considering the earthquake relief task. Define the index system weight through applying the analytic hierarchy process and using the utility function to combine the quantitative and qualitative index. Results showed that, the performance and evaluation result of rescue equipment system is medium which accords with reality of the army; Although there are many earthquake relief equipment arranged for the rescue unit, many performance like the varieties of detection equipment, the ranging accuracy of search equipment, the weight of shore equipment, the largest removal distance and weight of obstacle removal equipment, and the constant working time of lighting equipment should be improved. The evaluation results accord with the real condition. Related Articles | Metrics

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Fireman's fire protective clothing and inner clothing's warmth retention properties study CAO Hui, XIA Jian-jun 2021, 40 (6):  897-900.  Abstract ( 1875 )   To guarantee northern fireman's better fighting efficiency in cold environment, the fire protective clothing and inner clothing's warmth retention properties were studied in this paper. Firstly, northern fireman's warmth retention requirement was determined based on questionnaire survey and relative standard. Tests show that current clothing test data couldn't meet warmth retention requirement. Secondly, fireman's underwear, fire- retardant sweater, floccules vest and fire protective clothing were improved by introducing polyimide fabric and new structure. Finally, different improved clothing composition was calculated respectively. Optimized compositions were recommended to different areas to guarantee northern fireman's better fighting efficiency. Related Articles | Metrics

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Development and application of software for fire prediction in petrochemical industry based on circular function HU Ren-yuan, LIU Yun, XIA Deng-you, LI Yong 2021, 40 (6):  901-905.  Abstract ( 1675 )   The methods used in the probabilistic deduction of the "scenario- response" emergency handling model have shortcomings such as strong subjectivity and insufficient pertinence. This paper takes petrochemical fire accidents as the object. Firstly, based on the analysis of the characteristic elements of the accident scenario evolution path node (scenario element), it collects more than two hundred petrochemical fire historical cases, uses text mining and transforms them into digital codes, based on database management software SQLift constructs the scenario evolution path database. Then use the loop function in the Java programming language to call the database to solve the problem of determining the path node in the scenario deduction, and further realize the problem of determining the probability value of the deduction based on the frequency idea, and develop the "Petrochemical Fire Accident Scenario Deduction System" mobile APP according to the previous thinking. Finally, a fire accident in a liquefied petroleum gas storage tank area is used as an example to verify the feasibility of the scenario deduction method and deduction software proposed in this paper. Related Articles | Metrics

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Experimental study on the effect of filling pressure on the extinguishing efficiency of modified ammonium sulfatedry-water fire extinguishing agent WANG Yang, ZHU Guo-qing, CHAI Guo-qiang, ZHOU Ying, ZHU Yi-fan 2021, 40 (6):  906-908.  Abstract ( 1696 )   The new- type dry-water fire extinguishing agent has the characteristics of high efficiency, cheap and environmental protection. It combines the advantages of aqueous fire extinguishing agent and dry powder fire extinguishing agent. It will provide more choices for dealing with the new fire scenarios emerging with the development of society. By comparing the particle size distribution and fluidity of modified ammonium sulfatedry- water powder prepared by different solid-liquid ratio, it is found that the dry-water powder prepared with 1∶13 solid-liquid ratio can meet the requirements of fire extinguishing agent well at the speed of 3 000 r/min and stirring time of 6 min. Then, the fire extinguishing experiments under different release pressure conditions were carried out. By comparing the experimental phenomena and experimental data of nine groups of experiments, it is found that the best fire extinguishing efficiency is obtained under the filling pressure of 0.6～0.7 MPa. Related Articles | Metrics

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Experimental study on the influence of marine environment on combustion characteristics of flexible polyurethane foam CHEN-Hu, HUANG Yu-jin, HE Hong-zhou, LIU Zhong-qing, CHEN Yan-gui, ZHUANG Huang-huang, 2021, 40 (6):  909-913.  Abstract ( 1664 )   Made a experimental study of combustion characteristics of flexible polyurethane foam (FPUF) as a common upholstered furniture filler and variation characteristics of asphyxiating gas components in combustion flue gas. Also the effective dose fraction FED model was used to evaluate the smoke toxicity. The results show that the development law of FPUF heat release rate (HRR) curves under the action of droplet deposition with different salt humidity is basically similar in both forced ignition mode and non- forced ignition mode.The ignition time of FPUF lengthens with the increase of fog droplet salinity in the non-forced ignition mode, but it is similar in the forced ignition mode. The variation rules of each flue gas component produced by FPUF combustion in air with different salt humidity are similar. When the equivalence ratio is 0.9 ~ 1.6, the high salt humidity air has a great influence on the formation of each flue gas component. Moreover, the presence of NaCl in the air with high salt humidity will promote the formation of asphyxiating gas components; the increase of salinity in the air with high salt humidity can enhance the toxicity of flue gas produced by FPUF combustion. Related Articles | Metrics

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Study of APP-DAP-CS intumescent flame retardant applied on polyoxymethylene WANG Han, CHAI Ying-li, LIU Yu-ting, LIU Hui-ping 2021, 40 (6):  914-917.  Abstract ( 1711 )   In order to improve the flame retardancy of polyoxymethylene (POM), the flame retardant POM composites were prepared by melt blending ammonium polyphosphate (APP) - diammonium hydrogen phosphate (DAP)-corn starch (CS) with POM. The samples were tested and characterized by limiting oxygen index (LOI), horizontal vertical combustion (UL-94), thermogravimetry differential scanning calorimetry (TG-DSC), scanning electron microscopy (SEM) and cone calorimeter (CONE). The results show that the LOI of flame retardant POM can reach 38 when APP: DAP: CS = 4:3:1, UL-94 grade is V-1.The heat release rate and total heat release are relatively small.The structure of carbon layer is compact and stable, which indicates that APP-DAP-CS intumescent flame retardant system can effectively inhibit the combustion of POM and has a good flame retardant effect. Related Articles | Metrics

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Thermal response behavior of unidirectional carbon fiber/epoxy resin prepreg PAN Yuan-yi, XU Yan-ying, CHEN Song-hua, CHEN Shao-jie, 2021, 40 (6):  918-922.  Abstract ( 1635 )   The different directions of thermal response behavior of unidirectional carbon fiber/epoxy resin prepreg under different high temperature environment were experimentally investigated. The results showed that the thermal response temperature and thermal conductivity of unidirectional carbon fiber/epoxy resin prepreg increased with the increase of thermal response time and then tended to be stable at a temperature lower than 230 ℃. In high temperature environment above 230 ℃, the thermal response temperature peaks, the material is gradually damaged, and the thermal response behavior is complex. In addition, the thermal conductivity of unidirectional carbon fiber/epoxy resin prepreg in the direction of plane and thickness was obtained, and the thermal conductivity in the direction of plane was always greater than that in the direction of thickness. Related Articles | Metrics

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Research of release performance of modified aerosol fire extinguishing agent YUAN Jiang-ying, GE Rui-rong, HUANG Yin-sheng, Mao Li, WANG Zhi-qiang, JIN Wen-bo, MA Jian-xing 2021, 40 (6):  923-925.  Abstract ( 1699 )   In order to effectively reduce the temperature of hot aerosol fire extinguishing agent and optimize the performance of aerosol fire extinguishing agent as much as possible, the influence of 9 kinds of chemical cooling agents on the temperature of aerosol fire extinguishing agent with the content of 3%, 5% , 7% and 9% is focused, and the changes of residue rate, mass burning rate and fire extinguishing time are considered. The release performance of chemical cooling agent modified aerosol fire extinguishing agent was comprehensively studied. The results show that the addition of chemical cooling agent has obvious cooling effect and can effectively shorten the fire extinguishing time, and ammonium oxalate has the best cooling effect. The residue rate will increase with the increase of the content of cooling agent. Basic magnesium carbonate and boric acid can obviously reduce the mass burning rate of fire extinguishing agent, while potassium carbonate and potassium bicarbonate can increase the mass burning rate of fire extinguishing agent. Related Articles | Metrics

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Review of identification methods of ignitable liquids WANG Yi-ming, ZHANG Zhi-wei, JIN Nan-jiang, LI Yang 2021, 40 (6):  926-928.  Abstract ( 1903 )   As a major type of fire that seriously affects the safety of people's life and property, arson fire has attracted the attention of fire investigators. According to data statistics, more than 80% of arson cases are using gasoline, diesel, high concentration of alcohol and other flammable liquids as accelerant, therefore, the inspection and identification of accelerant is a major research point to identify arson fires. In this paper, the methods of testing and identification of fuel additives are systematically summarized, and the detection methods include Raman spectroscopy, thin layer chromatography, Fourier infrared spectroscopy, GC-MS, thermal analysis-mass spectrometry, etc. At the same time, the research status of thermal analysis-mass spectrometry and its application are described in order to provide guidance for fire inspectors' identification and inspection. Related Articles | Metrics

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Raman spectral identification technology of the burned globules DING Shi-yi, YANG Han, WANG Jian 2021, 40 (6):  929-932.  Abstract ( 1703 )   In this paper, Raman spectral is used to test the adherent carbon of the copper conductor burned globules. The spectral characteristics such as peak position, peak shape and peak intensity of the sample spectrum are analyzed. And quantitative analysis of the Raman spectra is also performed after the peakdifferentiating using the five- band differentiating method. The results show that the Raman spectra of the burned globules wire samples with different fire temperatures and time are quite different. The width of the half D1 peak is small and the peak intensity is strong. ID2/IG approaches 0, ID3/IG and ID4/IG is relatively small. The conclusion of the study indicates that the Raman spectrum can effectively identify the burning traces of the globules, and provide guidance for the research of the cause of fire. Related Articles | Metrics

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Microstructure characteristics of overcurrent melt trace of aluminum alloy wire ZHANG Jin-bao, XIANG Yi-kun, ZHOU Guang-ying , LI Yang 2021, 40 (6):  932-935.  Abstract ( 1712 )   In order to determine the location of the arc fault point when the line overcurrent occurs, the overcurrent faults of AA8030 aluminum alloy wire under different overcurrent conditions are simulated, and the microstructure characteristics of the melt marks in different areas of overcurrent of the wire are analyzed by field emission scanning electron microscope. The results show that the micromorphological characteristics of the melting marks at the arc fusion point are honeycomb and snowflake. The signature micro morphology of the fusion mark in the non- arc area is the needle- shaped trace. The characteristic microscopic appearance of the slag area outside the arc melting point is spherical trace. This conclusion can provide reference for investigators to judge the fault point of overcurrent arc. Related Articles | Metrics

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General situation of inspection and identification of combustion promoter at fire site at home and abroad LI Kang-xu, JIN Jing, LI Qiu-fan-zi 2021, 40 (6):  936-940.  Abstract ( 1751 )   In order to visually show the research situation and hot spots of testing and identification of combustion improvers in fire field in China and other countries, in this paper, using the databases of CNKI and WoS, and using the methods of bibliometric analysis, knowledge map analysis, visual analysis, etc., the literature on the inspection and identification of combustion supporting agents in fire scene is statistically analyzed. Through CiteSpace visualization software, this paper comprehensively analyzes the published articles, core authors, research institutions, core journals, research hotspots and other issues in the field of fire accelerant inspection and identification in China and other countries, trying to visually show the general situation of domestic and foreign research, and draw a network map to visually present the above contents. Related Articles | Metrics

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Study on the characteristics of heat trace of hot dip galvanized color coated plate in fire DENG Zhao-yun, JIN Jing , ZHAO Yu-chen 2021, 40 (6):  941-944.  Abstract ( 1714 )   In order to understand the trace characteristics and formation mechanism of the color coated plate after heating in detail, it can provide reliable trace evidence for the fire control personnel to accurately identify the cause and point of fire in the fire scene. In this paper, the characteristics of the heat trace of the color coated plate are described and studied in detail by changing the temperature and holding time. The macroscopic trace of hot-dip galvanized color coated steel plate is mainly reflected in the change process of coating shape and color. The main process is that the coating does not change, the paint layer changes to light yellow, the powder paint layer cracks, the paint layer falls off, and the sample is completely black. It can help the fire investigators to judge the heat trace of the color steel plate more accurately by the change of the sample surface. Related Articles | Metrics

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Investigation and prevention analysis of a warehouse fire accident ZHANG Yan-ni, HUANG Luo-xin, LI Yang, LIU Feng, WEN Xin-yu 2021, 40 (6):  945-949.  Abstract ( 1772 )   In order to identify and divide the responsibility of a fire accident caused by a warehouse jointly managed by multiple companies, video analysis technology was used to build an experimental platform to simulate the fire source and analyze the location of the fire source. The fire prevention scheme of this kind of warehouse was given through modeling analysis. First, the accident is investigated and analyzed to determine the reference line. Next, the fire site is simulated by building an experimental platform to determine the location of the initial fire source. Then, on the basis of determining the location of the fire warehouse, the physical model is established by FDS. Finally, through comparative analysis, the fire prevention measures of this kind of warehouse are obtained. The experimental results show that the distance between the bright area of warehouse C and the accident site is 12.78 m, which is consistent with the data, 12.70 m. Therefore, the initial location of the fire source is the warehouse C. In the fire prevention of this kind of warehouse, attention should be paid to the problems of cargo placement, smoke exhaust and ventilation, and automatic fire extinguishing devices in the warehouse center. Related Articles | Metrics

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Fire investigation integrated platform based on multi system interaction ZHANG Xiang-zhi 2021, 40 (6):  950-954.  Abstract ( 1791 )   The problems of fire investigation module of existing fire supervision system are analyzed. Combining with the usage of fire investigation module of fire supervision system as well as the fire investigation situation and task, the design idea of fire investigation integrated platform based on multi system interaction is put forward. The fire investigation integrated platform design principle and target are summarized. The overall structure, application structure and data structure is introduced. The subsystems are introduced, including case handling system, on site recording system, material evidence system, etc. Related Articles | Metrics