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15 February 2020, Volume 39 Issue 2 Previous Issue    Next Issue

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Fire protection system design for container lithium ion battery energy storage system ZHANG Yang, LV Zhong-bin, YAO Hao-wei, WANG Chao, WANG Chang-jun 2020, 39 (2):  143-146.  Abstract ( 2100 )   In order to improve the overall safety of containerized lithium- ion battery energy storage system, based on system construction and working principle of the containerized lithium-ion energy storage system, the firefighting requirements of the energy storage system were analyzed. The thermal management system of container lithium- ion battery energy storage system was built and simulated. Aiming at the fire extinguishing safety of container lithium- ion battery energy storage system, a new type of fixed-point and positioning coupling fire extinguishing device was proposed.The study can improve the performance of the fire extinguishing device of this kind of energy storage system, promote the construction of three-type two-network of State Grid Corporation. Related Articles | Metrics

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Characteristic parameter analysis of thermal runaway early warning of lithium-ion battery LI Zhao, CHEN Cai-xing, NIU Hui-chang, LI Lei 2020, 39 (2):  146-150.  Abstract ( 1972 )   In order to support the early warning model of thermal runaway(TR) of lithium-ion battery, experiments were carried out focusing on the issues of battery cell TR by unilateral heating, to analyze the variation regularity of characteristic parameters such as battery surface temperature, voltage and gas temperature. The reasonable alarm range of the above parameters is analyzed base on the reduction of false or missing rate. Experimental results indicate that the determination of TR triggered by heating mainly depends on the battery surface temperature rise rate. And the battery voltage drop is inapplicable to TR warning. The reference alarm range of characteristic parameters such as battery surface temperature,surface temperature rise rate, voltage drop rate, gas temperature is 60~90℃,0.4~1℃/s,0.05~0.16V/s,60~90℃, respectively. Related Articles | Metrics

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Research on water curtain smoke blocking technology of urban underground road JIANG Xue-peng , WANG Bao-wei , 2020, 39 (2):  149-154.  Abstract ( 1764 )   In order to quantify the effect of the water curtain, the water curtain system parameters based on the water curtain momentum ratio R and the smoke resistance efficiency η are constructed through theoretical analysis. The FDS was used to simulate the 50 sets of working conditions under different water spray intensity and longitudinal wind speed for5MW,10MW and15MW fire scales. The results show that the larger the momentum ratio is, the lower the smoke resistance efficiency is. Under the three fire sources of 5MW,10MW and15MW, the best effective smoke resistance momentum ratio is 4.35×103,2.44×103,2.10×103, respectively.The effectiveness of the water curtain to prevent smoke is verified from the microscopic (flow field). Under the three fire sources of 5MW,10MW and15MW, the optimal water spray intensity is 2.0L/(m·s)，2.0L/(m·s),2.5L/(m·s) respectively，and the water curtain spray intensity increases, the cooling effect increases, but the tunnel visibility decreases, and the smoke blocking effect is weakened. Related Articles | Metrics

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Experimental study on the combustion characteristic of sodium metal under heat radiation ZHENG Ze-xun , LI Jin-mei , LI Qiang , WANG Yong-gang 2020, 39 (2):  154-158.  Abstract ( 1758 )   Research on the combustion characteristics of sodium metal was conducted on cone calorimeter with various surrounding radiation heat flux from 25kW/m2 to 60kW/m2, and the oxygen content in combustion gas and residual mass were measured. The result showed that: with the surrounding radiation heat flux increasing, there were big differences in the combustion phenomena of sodium metal, and the residual mass decrease, until the complete combustion happened. An ambient radiation heat flux smaller than 30kW/m2 is unable to trigger a flame burning for Sodium metal.When the radiation heat flux is 50~60kW/m2 , the unstable and inadequate open fire happened. When the radiation heat flux is bigger than 60 kW/m2 stable and fully open fire happened. Related Articles | Metrics

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Interference of solvent-type neoprene on gasoline identification XUE Teng, ZHANG Jin-zhuan 2020, 39 (2):  157-161.  Abstract ( 1787 )   Based on gas chromatography-mass spectrometry and pyrolysis gas chromatography-mass spectrometry, the obtained neoprene solvent, colloid and its combustion residue spectrum were compared with the 120# gasoline sample and its combustion residue spectrum. The results showed that the original spectrum of the chloroprene solvent and the 120# gasoline spectrum were similar, but there were still differences. The toluene content in the chloroprene solvent was higher, and the toluene was not contained in the 120# gasoline. The aromatic components of 120# gasoline burning residue and neoprene combustion residue can be detected, and the characteristic components in the traditional fuel gasoline of fused aromatic hydrocarbons will interfere with the identification of traditional fuel gasoline. If 2,6-di-tert-butyl-p-cresol is found in the test sample, 1-tert-butyl-2-methoxy-4-methylbenzene can eliminate the interference of neoprene on gasoline. The experimental results can provide reference for the identification of adhesive fire evidence such as neoprene. Related Articles | Metrics

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Research on thermal runaway characteristics of ternary lithium ion battery in low oxygen environment ZHANG Shao-yu, DONG Hai-bin, XIAN Xue-lei, YI Cheng-yi, LI Yi, LIU Lian-xi, YU Dong-xing, SHENG Yan-feng, MA Jian-qin, ZHAO Qing-song 2020, 39 (2):  161-164.  Abstract ( 1843 )   The thermal runaway characteristics of NCM811ternary soft-packed lithium ion battery in closed space with oxygen concentration of 21% and 10.64% were studied. The experimental results show that when the oxygen concentration is 21%, continuous flame and then mars is sprayed. When the oxygen concentration is down to 10.64% , continuous flame is not formed on mars. The fact that the mars ejected during the thermal runaway of the battery can burn briefly in a low-oxygen environment, but the mars cannot form a continuous flame indicates that the thermal runaway of NCM811ternary lithium ion battery is a process of releasing oxygen, but the oxygen released by the battery is not enough to sustain the continuous combustion of mars. Related Articles | Metrics

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Experimental study on pyrolysis of five broad-leaved wood leaves in northeast GAO Fei-fei, XIN Ying, WANG Xin-ran, LI Jia-xin 2020, 39 (2):  164-167.  Abstract ( 1802 )   Pyrolysis process and dynamic characteristics of5com⁃mon broad-leaf species in Northeast China, such as white birch, ashtree, mongolian oak, abele and salizmatsudana,was studied by thermogravimetric analysis. The heating rates were 10,15,20℃/min and particle sizes were40,60,80mesh. The pyrolysis process of experimental materials was analyzed in a nitrogen atmosphere and the kinetics was studied by Gorbatchev integral method. The experimental results showed that the pyrolysis process of the samples can be divided into4 stages: water loss, slight weightless⁃ness, main weightlessness and carbonation, among which the main weight loss stage had the most weight loss. The order of flammability of the 5samples is as follows: abele > mongolian oak > salizmatsudana > ashtree > white birch, and the order of activation en⁃ergy is as follows: white birch > ashtree > salizmatsudana > mon⁃golian oak > abele. The stronger the flammability, the smaller the activation energy. The higher the heating rate, the higher the initial temperature and termination temperature of pyrolysis reaction,and the fasterthe weight loss rate, the more adequate the pyrolysis reaction. Related Articles | Metrics

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Influence of heat radiation intensity on the combustion characteristics of cotton ZHAO Zhi-xin, CAI Wei, WANG Xin, HU Yuan, ZENG Wen-ru 2020, 39 (2):  167-171.  Abstract ( 1842 )   Thermal radiation ignition experiment of two groups of cotton with mass of 10 and 20g were carried out by cone calorimeter. The heat radiation intensity is 35,30,25,20,15,10,5,4,3 and 2kW/m2 respectively. The heat release rate curve, total heat release curve, combustion residue morphology and residual mass were compared and analyzed. The results showed that when the cotton is burned, there is always smoldering at the same time. The peak of the heat release rate of open flame combustion is higher than the maximum value of the heat release rate of the smoldering under the same conditions, and increases with the increase of the scale. There is no peak in the smoldering heat release rate curve and the heat release lasts longer. The critical igniting heat radiation intensity of cotton sample with size of 100mm×100mm×24mm and mass of10g is2~3kW/m2; and that of cotton sample with size of 100mm×100mm×24mm and mass of20g is4~5kW/m2. As the increase of bulk density and relative humidity of the sample, the critical igniting heat radiation intensity increases Related Articles | Metrics

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Comprehensive analysis of combustion performance and environmental performance of campus furniture panels XU Zhi-hao, HE Li-hui, ZHONG Wen-han, HU Tian-yi, LU Chen-xi 2020, 39 (2):  170-174.  Abstract ( 1831 )   Based on the artificial boards commonly used in campus furniture at present, the combustion performance and environmental protection performance of the boards were tested respectively, and the comprehensive performance evaluation of the boards was obtained through the five key performance indexes of ignition time, peak heat release rate per unit area, total heat release, total smoke production and formaldehyde release. The results show that with the increase of radiant illumination, the flame retardant property of the plate will decrease. The burning time of the impregnated paper was improved, but the heat release rate, total heat release and total smoke production were different. Plywood and impregnated paper veneer plywood have high heat release rate, high smoke yield and poor flame retardant performance. Related Articles | Metrics

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Effect of polypropylene fiber on the performance of concrete after high temperature LIU Xiao-xian, DU Hong-xiu 2020, 39 (2):  173-177.  Abstract ( 1716 )   In order to study the effect of polypropylene fiber on the tensile strength of C80 high performance concrete (HPC) after high temperature, the high temperature test was carried out on C80HPC containing 0, 0.1% and 0.2% polypropylene fiber, and the cracking of concrete was observed and recorded. After the tensile strength test was carried out, the infrared temperature rise of the cross section of the C80 HPC was detected by infrared thermal imager. The relationship between the tensile strength of the HPC, the infrared temperature rise and the temperature of the fire was analyzed. The results show that the incorporation of 0.1% polypropylene fiber in C80 HPC can inhibit the occurrence of bursting; the tensile strength of HPC decreases with the increase of fire temperature, and the incorporation of polypropylene fiber will reduce the tensile strength of HPC. The established regression equation of fire temperature and infrared average temperature rise and tensile strength can be used to identify the fire temperature, residual strength and post-building recovery of HPC after fire. Related Articles | Metrics

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Study on flame propagation law of HMX dust cloud flame SU Zeng-qiang, HU Li-shuang, HU Shuang-qi, YAO Ya-jing, ZHANG Wei, LIU Yang, DUAN Yu-hang 2020, 39 (2):  177-181.  Abstract ( 1759 )   By using the improved visual Hartmann device,the flame propagation law of HMX dust cloud explosion was studied, and the effects of different HMX dust cloud concentration and particle size on the flame propagation velocity and height of dust cloud explosion were observed. The results showed that, concentration of HMX dust changed from 74.1 g/m3 to 185.1 g/m3, the maximum height of flame propagation increased from 29.97 cm to 60.81 cm, and the maximum velocity increased from 58.91 m/s to 175 m/s. The amplitude of flame fluctuation increased with the increase of concentration, and the flame fluctuation appeared obviously earlier. When the particle size of HMX dust increases from 19.02 μm to 53.56 μm, the maximum height of flame propagation decreases from 55.45 cm to 40.02 cm, the maximum flame propagation velocity decreases from 181.93 m/s to 121.28 m/s, the flame fluctuation amplitude decreases obviously, and the flame fluctuation appears delayed.  Related Articles | Metrics

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Study on the characteristics of flammable dust induced by welding flame ZHANG Yan, WANG Song, REN Chang-xing 2020, 39 (2):  180-183.  Abstract ( 1734 )   Through the statistical analysis of several dust explosion accidents, taking open fire as a common ignition source as the research object, test device was developed to study the characteristics of combustible dust induced by open flame represented by welding flame. Experiments were carried out by using corn starch, lycopodium dust and coal powder as test materials to study the characteristics of igniting combustible dust by open fire. The maximum temperature of corn starch and lycopodium dust in the combustion process were 956 ℃and 855 ℃. The mass concentration of dust ignited by open fire in semi-open space is significantly higher than the LEL measured by 20 L spherical device. Open flame is not easy to ignite the dust, such as coal dust, that is insensitive to temperature ignition source. Therefore, when determining the flammability of dust, open flame could be used as a preliminary screening method and 20 L spherical device is the final method to determine the combustibility of dust. Related Articles | Metrics

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Effect of trace Cu2+ on thermal stability of cumene hydrogen peroxide WANG Fei, QIN Zhi-yi, LIU Hui-ping 2020, 39 (2):  183-186.  Abstract ( 1749 )   In order to study the effect of trace copper ions (Cu2+) on the thermal decomposition of cumene hydroperoxide (CHP), adiabatic accelerated calorimetry (ARC) was used to test the adiabatic decomposition of CHP and CHP containing two different concentrations of Cu2+. The effects of different concentrations of Cu2+ on the thermodynamic parameters and decomposition activation energy (Ea) of CHP initial decomposition temperature (To), maximum decomposition temperature (Tf), adiabatic temperature rise (△Tad), maximum temperature rise rate (mm), and the experimental data was corrected using the thermal inertia factor (Φ). The results show that the addition of trace Cu2+ has an effect on the thermodynamic parameters of CHP decomposition, and the effects of different concentrations are different. For example, the corrected initial decomposition temperature (To, s) and Ea of CHP are 111.28 ℃ and 170.93 kJ·mol-1, after adding (1.85×10-3)% or (3.70×10-3)% Cu2+. The corresponding parameters are 104.26 ℃, 164.73 kJ·mol-1 and 98.87 ℃, and 145.63 kJ·mol-1. It is indicated that the presence of trace Cu2+ can reduce the initial decomposition temperature To,s and activation energy Ea of CHP, and the higher the concentration, the more obvious the decrease, thus increasing the thermal decomposition risk of CHP. Related Articles | Metrics

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Study on modification of fire resistance of cement wallboard by nano materials SUN Xiao-jue, XU Rui-yu 2020, 39 (2):  186-190.  Abstract ( 1702 )   In order to improve the fire resistance of cement wallboard structure, nano materials which are micro silicon powder and carbon fiber were used as admixture to study the material modification. Test pieces were prepared with the mass ratio of standard sand and Portland cement of 2∶1. The compressive strength, flexural strength, fire resistance and dry shrinkage were tested and the micro morphology was analyzed. The results showed that micro silicon powder and carbon fiber can not only improve the compressive and flexural strength of cement masonry, but also improve its fire resistance. The cement wallboard with double addition of micro silicon powder and carbon fiber content of 3% and 2% has the best fire resistance, and the mass loss after combustion test is 0.64%, 85% lower than that of the reference group. It is found by micro morphology of cement based modified materials that the filling effect of ultrafine silica powder particles is the main reason for the improvement of material strength performance, and the bonding effect and surface reaction of carbon fiber are the main reasons for the improvement of fire-resistance performance. Related Articles | Metrics

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Propagation of gas explosion wave in typical residential building and design of explosion-proof kitchen ZHOU Qing, QI Lin, DING Jie, SUN Liang 2020, 39 (2):  189-194.  Abstract ( 1799 )   Based on the numerical analysis method, the finite element model of typical residential building was established by LS-DYNA software. The propagation law and overpressure load of gas explosion wave with different volume ratio θ in residential space were studied. The dynamic response and failure mode of masonry structure and reinforced concrete structure kitchen under gas explosion load were analyzed. The explosion-proof kitchen considering explosion-proof requirements was put forward and its explosion-proof effect was verified. The results showed that the peak overpressure does not decrease significantly when gas explosion wave propagates from kitchen to living room. Due to the reflection of the walls on both sides, the peak overpressure will increase significantly when the explosion wave propagates to the end of the corridor. The explosion-proof effect of reinforced concrete structure kitchen is obviously better than that of masonry structure. For kitchen with explosion-proof requirements, reinforced concrete structure should be preferred. The explosion-proof kitchen designed on the basis of reinforced concrete structure kitchen can reduce the damage of gas explosion wave to kitchen structural components and prevent the explosion wave from entering the interior space of the house. Related Articles | Metrics

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Verification of large scale calorimeter with n-heptane pool fire YANG Xiao-han 2020, 39 (2):  194-196.  Abstract ( 1774 )   with regard to large scale calorimeter, the test in the tunnel calorimeter was carried out to correct the fire heat release rate and total heat release amount of n-heptane oil pool. Cold flow field correction was used to understand the stability and uniformity of gas flow in exhaust pipe. The pool fire correction test of n-heptane oil was carried out under different number and arrangement of oil pan. The results showed that: in the cold flow field calibration test, the volume flow rate of gas in the exhaust pipe maintains at 27.9 m3/s constantly. Through the comparison and analysis of the errors between the measured calorific value and the theoretical calorific value, the error between the measured calorific value and the theoretical calorific value is less than 10% in 6 of the 7 tests. Related Articles | Metrics

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Influence of smoke exhaust modes on personnel evacuation in subway station WANG Jian-guo, WANG Jing-wei, SU Jun-kai 2020, 39 (2):  196-200.  Abstract ( 1725 )   In order to study the effects of different smoke exhaust modes on the evacuation in a fire scenario, a double-deck island subway station was taken as example, the fire model was established by FDS, and the distribution of fire smoke temperature, CO concentration and visibility of subway stations under 4 exhaust modes were analyzed. Within the specified evacuation time of 360 s, at the height of the human eye as 1.6 m, the evacuation route under the natural smoke exhaust mode has the area which temperature is greater than 60 ℃, CO volume fraction is greater than (250×)10-6, and visibility is less than 10 m. Under the evacuation mode of the smoke exhaust, there is an area with visibility less than 10 m in the evacuation route. The mode of smoke exhaust in the public area of the station, and mixed smoke exhaust of station public area and station tunnel, the fire smoke temperature, CO concentration and visibility in the evacuation route area are lower than the evacuation index. Related Articles | Metrics

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Influence of urban underground space connection project on evacuation LIANG Jing 2020, 39 (2):  200-204.  Abstract ( 1701 )   The underground space of a large CBD connects 7 independent areas through 11 connecting channels. Pathfinder was used to analyze the effect of considering the available passageway as the indoor relative safety emergency exit on the evacuation efficiency quantitatively by 11 scenarios. The evacuation time after increasing the connecting ports and the evacuation flow of each connecting port in typical areas were analyzed. The results showed that people near the company channel can make full use of it for evacuation, and the increase of the path can optimize the evacuation, its conducive to improving evacuation efficiency. Related Articles | Metrics

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Research on dynamic fire scale and personnel evacuation of urban road tunnel WANG Ming-nian, HU Xiao-yue, YU Li, GUO Xiao-han, TIAN Yuan, 2020, 39 (2):  203-208.  Abstract ( 1726 )    In order to determine the dynamic fire scale and personnel evacuation scheme of urban road tunnel under fire spreading, the vehicle ignition time is calculated based on critical radiant heat flux theory.In addition, a full scale model built by FDS is applied to determine the dynamic fire scale under obstruction and to compare the distribution laws of temperature and visibility under two cases, namely, opening both two side cross passages at the same time and opening only one side cross passage. Furthermore, the evacuation time under two cases are compared through Pathfinder. Results show that, initial ignition needs 250 s, and the secondary ignition needs 615 s and 650 s, respectively. The maximal heat release rate of the fire reaches up to 39.1 MW, and a total of 11 vehicles were involved in the combustion. The laws of temperature and visibility distribution are basically the same under two cases but the evacuation time of opening both two side cross passages is only 390 s, which reduces by 320 s compared with the latter. It is suggested that in case of fire in four-hole road tunnel, the cross passages on both sides should be opened at the same time. It is suggested to take timely fire protection measures within 10 min to prevent the secondary ignition of the vehicles. Related Articles | Metrics

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Performance-based design of smoke exhaust in  long and narrow underground space XIANG Jian-yu, MAO Jin-feng, YU Nan-tian 2020, 39 (2):  208-213.  Abstract ( 1742 )   Based on the structural characteristics of a long and narrow underground project, the communication work area of the project is simulated by FDS software. Through the means of performance-based design, setting fire scene and personnel density reasonably, the smoke exhaust effect of two-way corridor and one-way corridor under different mechanical air supplement conditions is studied, and the performance-based evaluation of personnel safety evacuation is carried out. The results show that when mechanical exhaust is adopted for the project model, the mechanical air supplement ratio should not be too large, and the mechanical air supplement volume should be 50% ~ 75% of the exhaust volume. Related Articles | Metrics

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Smoke control of side platform and the same concourse of metro transfer station ZHOU Feng 2020, 39 (2):  213-217.  Abstract ( 1806 )    In order to improve the overall fire safety of the station as the starting point, in view of the situation that the side platform and the common station hall of the large-scale subway transfer station are on the same floor, the corresponding fire separation measures are proposed on the basis of the specification requirements, and the possible problems of the smoke control mode of the side platform are analyzed. Finally, combined with specific engineering cases and FDS simulation study, the corresponding design suggestions are put forward in order to provide experience for similar projects. Related Articles | Metrics

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Structure fire resistance and fire protection design analysis of a drum-type high-rise hotel ZHENG Jin, HUANG Gang 2020, 39 (2):  217-220.  Abstract ( 1749 )   Taking a drum-type high-rise building as an example,aiming at its unique shape, novel appearance and distinctive national characteristics, taking the difficulties existing in structural fire resistance and fire protection design as the breakthrough point, on the premise of ensuring the structural fire resistance and building fire safety of the building, according to the relevant national codes and standards, based on the concept of structural reliability and intelligent fire protection, the structural fire-resistant materials, safe evacuation, fire climbing operation site and fire fighting facilities design are discussed. It is proposed that the coupling of fire and wind load should be fully considered in the design of similar drum-type high-rise buildings, and the new technologies of intelligent fire control should be actively applied to improve the structural reliability and fire safety. Related Articles | Metrics

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Experimental study on the influence of fire insulation belt on fire spread of external wall BAO Xiao-meng 2020, 39 (2):  219-223.  Abstract ( 1776 )   In order to study the influence of the fire insulation belt on the fire spread of external insulation system in the actual fire environment, starting from the practical application, the facade of a residential quarter is selected. When the B1 and B2 class insulation materials are used for the external insulation system of the building, the fire development process and the vertical center line temperature of the fire insulation belt on the entire actual external insulation materials under three different ignition positions are experimentally studied. Related Articles | Metrics

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Effectiveness of low-pressure twin-fluid water mist on suppression of thermal runaway of Lithium-ion batteries HE Yuan-hua, GUO Jun, WANG Hai-bin, SHEN Jun-jie 2020, 39 (2):  223-228.  Abstract ( 1834 )   Using the self-designed experimental platform, simulating the external overheating scene of lithium battery with heating rod, the surface temperature and CO volume fraction of thermal runway of 18650 Lithium battery were compared under 95, 80 and 60 kPa respectively. The inhibitory effect of low-pressure twin-fluid water mist on the thermal runaway of Lithium batteries was researched. The results showed that low-pressure twin-fluid water mist can produce smaller droplet at low atomization pressure, which can effectively inhibit thermal runaway and heat propagation of Lithium batteries, and reduce CO production. The fine water mist of 1.2 MPa produces the smallest droplet and the best cooling effect. As the environmental pressure decreases, the effect of the suppression of water mist declines. Inert gas can be considered as atomizing gas to enhance the fire extinguishing effect. Related Articles | Metrics

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Influence of wind speed on fire suppression of water mist in pipe gallery WANG Zhi-yuan, LI Yan-feng, WANG Hong-yi, DUAN MU Xiang-ling 2020, 39 (2):  228-231.  Abstract ( 1732 )   Numerical model of equal proportion comprehensive pipe gallery was established and the fire suppression of the cable cabin fire by water mist under the ventilation speeds of 0, 0.4, 0.8 and 1.2 m/s was simulated by FDS. The influence of wind speed on fire extinguishing and the smoke spread under the combined action of longitudinal ventilation and water mist were researched. The results showed that with the increase of longitudinal ventilation wind speed, although the oxygen content in the tunnel increases, the temperature at and above the fire source drops, which greatly reduces the vertical development trend of the fire source. The effectiveness of the high pressure water mist fire extinguishing system is proved by the results. When the water mist system is used in the urban comprehensive pipe gallery, it is more advantageous to apply the ventilation airflow with the wind speed no higher than 1.2 m/s to extinguish the fire by water mist. Related Articles | Metrics

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Research of dry powder extinguishing device applied in low-temperature wind turbine PENG Yan-hua 2020, 39 (2):  232-236.  Abstract ( 1686 )   In order to evaluate the wind turbine fire fighting capacity of the dry powder extinguishing device in extreme low temperature environment，2 m3 small space and 56 m3  large space fire extinguishing test device was established. In the -30 ℃ low temperature environment, the fire extinguishing test was carried out by means of the dry powder extinguishing device. The start-up performance, injection performance and fire extinguishing performance of the fire extinguisher was tested. The test results show that dry powder extinguishing device can start normally discharge under low temperature conditions. The fire extinguishing performance of super fine powder was not affected by low temperature. The super fine powder can put out class A and class B combustibles of the wind turbine. Low temperature has a significant effect on the diffusion characteristics of dry powder. If the fire fighting design uses the total flooding extinguishing way, the simulation fire suppression test should be carried out to verify the effectiveness. Related Articles | Metrics

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Experimental study on smoke characteristics of  reduced scale test fires LI Li-ming, SONG Li-wei, WANG Li 2020, 39 (2):  235-239.  Abstract ( 1785 )   The experiments of smoke characteristics of the reduced scale test fires were carried out based on the 4 standard test fires. The change rule of smoke characteristics of test fire in the process of gradual reduction of its scale was studied and the change of the obscuration coefficient of fire smoke with time was analyzed. Alarm response characteristics of rack fire detector, inspiratory smoke fire detector and point smoke fire detector to test fire of various scales was analyzed too. Suggestions for fire test with reduced scale suitable for detection and evaluation of high sensitive fire detectors were given. Related Articles | Metrics

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Research on monitoring and fire extinguishing technology for wildfires near transmission line based on UAV ZHOU Te-jun, LI Bo, TAN Yan-jun, WU Chuang-ping, WU Wei, PAN Bi-cheng 2020, 39 (2):  239-243.  Abstract ( 1797 )   Using UAV carrying 3D laser, the transmission line, tower and undergrowth vegetables were identified, to assess the wildfire risk. Use UAV carrying YCbCr color and space detection and analysis modular to identify the wildfire. The fire extinguishing method such as the UAV ballistic launch, throwing fire extinguishing ball and small flow anti-evaporation jet for the initial wildfire were proposed to put out the fire quickly. Related Articles | Metrics

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Gas detection and identification method based on viscosity characteristic YANG Song-cheng, BAO Yu-peng, ZHAO Lan-ming, 2020, 39 (2):  243-247.  Abstract ( 1723 )   A gas component detection method based on differential pressure principle was proposed. By measuring the differential pressure signal response of the gas to be measured after passing through the special viscosity sensor, the gas viscosity data can be obtained through conversion. The gas composition can be obtained by inversion according to the quantitative relationship based on Poiseuille's law and the viscosity theory of mixed gas. The experimental results proved the feasibility of gas recognition using viscosity in theory and practice. Verification tests based on flowrate reference value and linear equation slope were carried out. Results showed that both two methods are effective ways to accurately identify the 4 unknown gas samples. Related Articles | Metrics

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Recognition and extraction of flames based on visible light images GE Jun, WANG Li, LI Wei, ZHANG Bo 2020, 39 (2):  247-251.  Abstract ( 1791 )   The basic characteristics of flames were analyzed, and several representative flame characteristics were selected as criteria to identify and extract flame areas in the fire field image. Based on the luminance characteristics of flame, the suspended flame area was divided by region growing method. According to the corresponding relation of RGB and HIS color model, and by separating the R, G, B component of flame pixels, the color distribution rules of flame were verified. The interfere of regular light source was excluded by roundness criterion. Related Articles | Metrics

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Solubility measurement and simulated calculation of Nitrogen in HFC-227ea XIAN Xue-lei, ZHANG Jun-na, ZHAO Qing-song, LIU Lian-xi, DONG Hai-bin, SHENG Yan-feng, MA Jian-qin 2020, 39 (2):  250-253.  Abstract ( 1861 )   In order to study the solubility of nitrogen in HFC-227ea, the solubility at different temperatures and pressures was measured by pressure-volume-temperature(PVT) apparatus. Then systematically discussed the effects of temperature and pressure on the solubility and Henry coefficient. Finally, based on the experimental data, the solubility model of nitrogen in HFC-227ea was established. The research shows that increasing temperature is benefit for N2 dissolution and the N2 solubility will increase with the pressure reducing in HFC-227ea. The fitting effect of nitrogen dissolution model in sevofluoropropane is better, and the maximum deviation is less than 3%. Related Articles | Metrics

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Study on acute toxicity of water based extinguishing agent and materials CHEN Pei-yao, SUN He, FENG Meng, JIANG Ling-zhi 2020, 39 (2):  253-256.  Abstract ( 1754 )   As a reference for product development and ecological risk assessment, acute toxicity(LC50) of raw materials and final products in water based extinguishing agents on zebre fish was studied using standard test method. Results showed that acute toxicity of extinguishing agent had no necessary correlation with freezing point but increased with fire-fighting level. Multiple hydrocarbon surfactants and fluorinate surfactants have high toxicity,sodium dodecyl sulfate and cocoamidopropyl Betaine even belong to highly toxic compounds according to toxicity criteria against fish. Considering acute toxicity,these highly toxic materials should not be used or should be little used in water based extinguishing agents while developing environment friendly products. Related Articles | Metrics

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Discussion on safety management of "one mechanism and two regulations" for fire fighting and emergency rescue YANG Guo-hong 2020, 39 (2):  256-259.  Abstract ( 1872 )   Based on the analysis of the safety status quo of fire fighting and emergency rescue operations, the types and characteristics of the disaster are studied, and combined with the operation command process, the countermeasures of the safety control mechanism of the fire fighting and rescue site, the safety operation regulations of firefighters and the safety operation regulations of the emergency rescue team are put forward. The purpose is to control the safety of fire fighting and emergency rescue operations, improve the effectiveness of on-site safety management and control,and the ability of emergency avoidance and rescue, and minimize the casualties of firefighters. Related Articles | Metrics

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Research on the formulation method of practical and digital emergency plan of fire and rescue WU Jin-jin, HUANG Dong-fang, ZHANG Qian, DENG Bo-yu, SHU Xue-ming, 2020, 39 (2):  259-263.  Abstract ( 1762 )   The requirement analysis of practical and digital emergency plan of fire and rescue were conducted in points of presentation form, required information and required function. The overall framework of the practical and digital emergency plan of fire and rescue is introduced from the sensing layer, the transport layer, the platform layer and the application layer. The functions and generation methods of the plan are analyzed and explored from the intelligent fire alarm setting, the information support during firefighting stage, the auxiliary decision-making during the disposal stage, and the trace-based evaluation stage. The plan provides information support and decision-making support for fire fighters, and plays an important role in the daily drills, and practical fire-fighting. Related Articles | Metrics

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Study on the safety of internal attack in building fire fighting CAO Wen-pu, WANG Wei, SHANG Kao-ding 2020, 39 (2):  263-267.  Abstract ( 1839 )   Internal attack is the most effective way to put out building fires and save people's lives. This paper makes a statistical analysis of the casualties of firefighters in 2007-2016, and sorts out the risk factors of internal attack. On this basis, from two aspects of internal attack tactical safety awareness and internal attack technical safety measures, this paper deeply analyzes a series of internal attack safety problems such as the timing of internal attack, the establishment of internal attack command system, the danger signs and emergency measures. The research results can provide positive reference for firefighters' internal attack action safety. Related Articles | Metrics

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Risk evaluation of fire and explosion  accidents in oil tank zone ZHAO Jun-ru, XU Duo, TIAN Jun-dong, DAI Guang 2020, 39 (2):  267-270.  Abstract ( 1780 )   In order to research on the quantitative risk evaluation methods of the fire and explosion accidents in oil tank zone from a view of multi-factor coupling, firstly, the researchers recognize the risk elements of fire and explosion accidents in oil storage tank area from four aspects, i.e., people, machines, environment and management and research on the coupling effect between different risk elements through constructing the cause-result models of the risk elements in fire and explosion accidents in oil storage tank area based on system dynamics; secondly, the researchers do risk evaluation research of oil storage tank area through constructing interaction matrix, and obtain the risk weight and risk assessment grade of fire and explosion accidents in oil storage tank area from a coupling perspective; finally, apply this risk evaluation model in the real case of an oil storage tank area in Huizhou.The results show that the oil storage tank area is in middle risk level with serious status, and the main elements that affect the safety of the oil storage tank area include the risks of personnel violation operations, equipment failures, the lack in the enforcement level in safety management and personnel safety awareness. Related Articles | Metrics

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Fire risk alarming index of industrial buildings outside of winter Olympic venues REN Chang-xing, LI Jin, ZHANG Wang, LI Guo-hui, MU Yang-yang, ZHANG Yan 2020, 39 (2):  270-275.  Abstract ( 1737 )   In order to prevent fire accidents of industrial buildings outside of winter Olympic venues, the multiple factors and comprehensive risk assessment index system was studied by identifying fire risk factors of key place and facilities. The risk points of the key place and facilities were analyzed and classified, by statistical analysis of typical accident cases and potential fire identifications on sites, including ammonia-related refrigeration sites, power plants and supply chain financing. On account of risk theory with inherent fire risk, risk mitigation measures and real fire risk, the multiple factors and comprehensive risk assessment index system was presented, including sensitivity of winter Olympic games, regional characteristics, buildings properties, firefighting facilities condition, fire safety management and external rescue force. And the important degree of risk indexes was divided by risk ranking method. Some time-varying risk factors were dynamically collected and quantified, and this fire risk index system can identify and analyze multi-source risk with time-varying characteristics, and therefore improve the level of fire risk warning for industrial buildings outside of winter Olympic venues. Related Articles | Metrics

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Study on economic-population-fire systems based on coupling analysis SUN Peng-zhe, PANG Ji-hua MA Sheng-yun, YAN Zu-wei 2020, 39 (2):  275-278.  Abstract ( 1698 )   Based on the relevant data of China's economy, population and fire in China Statistical Yearbook and China Fire Yearbook from 2002 to 2016, the entropy weighting method was used to calculate the weights and comprehensive scores of China's economy-population-fire system. A model for coupling degree of coordination analysis was constructed to analyze if the economic population fire system is developing coordinately. The empirical analysis of the degree of coupling coordination shows that: China's economy population fire system is basically stable between mild deregulation and moderate declination, and the overall degree of coupling coordination has been increasing, but it has been in misaligned status. The relevant suggestions were proposed. Related Articles | Metrics

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Series fault arc detection based on 1D-CNN ZHOU Xin-cheng, WU Zi-ran, WU Gui-chu 2020, 39 (2):  278-282.  Abstract ( 1716 )   In order to improve the reliability of series fault-arc detection, an experimental platform is built according to the standard, and a real-time data acquisition device is made to collect both faulty and non-faulty current data generated by 4 types of linear or non-linear loads, including incandescent lamps, fluorescent lamps, air compressors and blowers. A one-dimensional convolutional neural network (1D-CNN) is proposed to inspect current signals in the circuit and determine whether fault arcs occur. Testing results show that the average detection accuracy of the model for all kinds of loads reaches 100%, and the loss is below 0.0007. We also transplant the model into an embedded system, and the accuracy reaches 96.25%. It is proven that the designed convolutional neural network structure can successfully detect series fault arcs and reduce the risk of fire. Related Articles | Metrics

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Research progress on paint thinner testing and identification ZHANG Jing-shun, ZHANG Guan-nan, ZHANG Yuan, ZHU Jun, WANG Wen, JIANG Hong, LIU Zhan-fang 2020, 39 (2):  282-285.  Abstract ( 1737 )   The basic knowledge of diluent and the standards, methods and instruments for diluent testing at home and abroad were summarized. The interference of fire site matrix, extraction and preservation of test materials on diluent identification was introduced. It is suggested that the method of chemometrics can be used to identify diluents. Twenty-three kinds of diluents were tested, and the difficulties of diluent test were analyzed. The prospect of diluent testing and identification was put forward. Related Articles | Metrics

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Investigation of a fire accident in a rubber factory's rubber powder workshop WANG Fu-wei 2020, 39 (2):  284-287.  Abstract ( 1804 )   A fire accident in a rubber factory rubber powder workshop was investigated. By fire scene investigation, survey visit and material evidence identification, the ignition time, ignition location and ignition point was identified, and the fire cause was analyzed. The current situation of fire safety management in the workshop was reported. In order to effectively prevent the occurrence of fire accidents in enterprises, some prevention measures against such fires were proposed. Related Articles | Metrics

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Investigation and analysis of a fire accident causing death in a high-rise residential building LI Hui 2020, 39 (2):  287-290.  Abstract ( 1753 )   In order to analyze the root causes of the high-rise residential building fire causing death, and effectively prevent the occurrence of fire and reduce the casualties caused by the fire, the author investigated a fire accident in a typical high-rise residential building. The paper introduces the identification process of the fire time, the fire position and the cause of the fire, puts forward the experience of the fire investigation, analyzes the causes of the frequent disasters of small fire in high-rise residential building causing death and the importance of the complete evidence chain in the investigation of fire accident, and finally, from the three aspects of fire promotion, the unit subject responsibility, the management responsibility of the industry, the suggestions of preventing this kind of fire were put forward. Related Articles | Metrics

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Investigation of a communication base  station battery fire HE Hua-jun, LIAO Ding-gen, GAO Huai-zheng 2020, 39 (2):  290-293.  Abstract ( 1940 )   Fire accident of a communication base station in Lanxi, Jinhua was introduced. The investigation team conducted the site investigation, material evidence identification, enquiry survey, and inquired the base station equipment operation background data such as electric current, voltage, personnel entry alarm, power failure alarm and smoke detector. The fire accident was analyzed and identified, and experience of such kinds of fire accidents were summarized.  Related Articles | Metrics