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15 August 2020, Volume 39 Issue 8 Previous Issue    Next Issue

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Effect of outdoor wind speed on temperature stratification and natural smoke extraction HUANG Dong-fang, LI Si-cheng 2020, 39 (8):  1041-1046.  Abstract ( 1783 )   Experiments of 1/3 scale were carried out to investigate the effect of outdoor wind on stratification characteristics and natural smoke exhaust in corridors. Fire power, outdoor wind speed and outside window size were variables and stratification characteristic of fire smoke in the corridor and the effect of natural smoke exhaust was judged. Critical failure wind speed of temperature stratification in the corridor and the critical failure wind speed of natural smoke extraction were found out. The relation between the dimensionless fire power and dimensionless critical failure wind velocity were researched by dimensional analysis and data fitting. It was found that there is a good linear relationship between dimensionless critical failure wind speed of temperature stratification and dimensionless fire power. The critical failure wind speed of temperature stratification increases with the decrease of window size.There is a significant logarithmic function relationship between the dimensionless critical failure wind speed of natural smoke exhaust and the dimensionless power of fire source. When the size of the window is the same, the higher the power of the fire source is, the higher the critical failure wind speed of natural smoke exhaust is. Related Articles | Metrics

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Research on leak detection and location of urban gas pipeline network based on RSSI algorithm WEI Li-ming, GUO Xi 2020, 39 (8):  1046-1049.  Abstract ( 1749 )   Abstract:Aiming at the problem of city gas pipeline leakage, this paper proposes a city gas pipeline network leakage and location technology based on RSSI algorithm. The algorithm analyzes and calculates the strength of the received signal between ZigBee nodes when the pipeline leaks, and finally obtains the location of the leak point. First, the algorithm model is established by using the RSSI signal strength value between the leakage target point and each receiving point, then the distance between the leakage point and each receiving point is obtained through the model, and finally the precise coordinate positioning calculation is obtained by the least square method. Simulation experiment results show that the algorithm proposed in this paper has high positioning accuracy and a wide range of applications. Related Articles | Metrics

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Experimental study on the influences of pedestrians stop on the movement of crowd with groups ZHANG Bo-si, CHEN Wen-yan, MA Xian, LIU Fu-peng, QIU Ping, REN Guo-you 2020, 39 (8):  1050-1053.  Abstract ( 1716 )   The experimental studies on the influences of pedestrians stop on the movement of crowd with groups were conducted in this study. Result showed that the walking speeds of group members and individuals decreased due to the group behavior and the stopped pedestrians. This decrease of walking speed of large group in the crowd is more remarkable. When hindered by the stopped pedestrians, the other pedestrians detoured. The individuals were apt to detour by the side of the stopped pedestrians. The walking behavior of groups when they detoured the stopped pedestrians depended on group size. The large group changed their configuration to gather as much as possible when they stopped,in order to avoid collision with the rear pedestrians. Related Articles | Metrics

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Study on the evolution mechanism of urban gas networks leakage disasters WANG Chun-xue 2020, 39 (8):  1054-1058.  Abstract ( 1734 )   In order to study the evolution mechanism of urban gas networks leakage disasters, a Bayesian network model of leakage disasters evolution was built. Types of disasters and damage targets were analyzed by counting the disasters, and the evolution chain of gas networks leakage disasters was established. Disaster factors during the evolution and their influence were identified,and the key nodes of the chain were analyzed though the evolution network structure. The results show that the gas networks leakage disasters are explosion, fire, suffocation, etc. And the main damage targets are residents' lives, buildings, other city lifelines, etc.The disaster evolution is the result of the effects of disaster environment factors, disaster - causing factors and disaster - affected factors. Leakage, fire disaster, explosion disaster, power supply facilities damage are the key nodes of the evolution chain of the urban gas networks leakage disasters. Related Articles | Metrics

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Pyrolysis characteristics and kinetic analysis of litter in fraxinusmandshurica plantation GAO Fei-fei, XIN Ying 2020, 39 (8):  1059-1061.  Abstract ( 1726 )   The thermogravimetric analysis was used to study the pyrolysis behavior of the litter under the fraxinusmandshurica forest.The effects of different experimental atmospheres, heating rates and particle sizes on the pyrolysis process were analyzed. The Coast- Redfern method was used for kinetic analysis. The results showed that the pyrolysis of the litter under the forest was divided into four stages: water loss, slight weight loss, main weight loss and carbonization. The stability of the samples was: branches>bark>leaves>Prenanthestatarinowii grass. There is one weight loss peak in nitrogen atmosphere, two in air atmosphere, and the weight loss rate is larger in the air atmosphere, and the pyrolysis is more sufficient. As the heating rate increases, the thermal weight loss curve moves to the high temperature side, the weight loss rate increases, and there is a hysteresis effect.The particle size has little effect on this experiment, the weight loss rate of the 60 mesh particle size sample is the largest.The activation energy of the four samples is from branches to bark, leaves and Prenanthestatarinowii grass. Related Articles | Metrics

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Anti-collapse performance evaluation of steel frame beam-column substructures considering damage of beams under blast loadings CHEN Ye, LI Yi, DU Yi-ming, SHI Ke-zhen, LIU Xuan-ya 2020, 39 (8):  1062-1065.  Abstract ( 1702 )   The numerical analysis model that considers the boundary condition of substructure was used, the deformation and damage of steel beam under blast loading were introduced into the anticollapse analysis of substructures, and the pressure- impulse curve plot and expression were established to evaluate the anti- collapse performance of steel frame beam- column substructures subjected to explosion. The parametric analysis was conducted out to investigate the effect of restraint stiffness and spandepth ratio. The results show that the arch action occurs at the first stage, then the flexural action works and the catenary action plays a key role finally. The reduction degree of anti-collapse performance of substructures may exhibit non- monotonic behavior as the intensity of the explosion increases. Except for the hinge joint, horizontalrestraint stiffness has a less effect on the development of the vertical resistance. The overpressure and impulse corresponded to the same index increases with the decrease of the span- depth ratio, but the substructure will trend to the shear deformation mode when the span depth ratio decreases to a low level, leading to the decrease of the ultimate deformation and maximum vertical resistance at the stage of catenary action stage. Related Articles | Metrics

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Optimization of building evacuation path based on improved ACO algorithm LIU Tao, JIA Sui-min 2020, 39 (8):  1066-1071.  Abstract ( 1804 )   Aiming at the problems of complex structures of large public buildings and difficulties in fire evacuation, an improved ant colony algorithm for optimizing evacuation paths was proposed.First,the Dijkstra algorithm is introduced for the basic ant colony algorithm(ACO),and the Dijkstra algorithm is used to calculate the suboptimal path with better globality to further strengthen the ini⁃tial pheromone distribution of the ant colony algorithm. Secondly,the transition probability,update rules,pheromone volatility coefficient, heuristic function, etc. of the ant colony algorithm are improved based on the real-time situation of the fire. Finally,a comparative simulation experiment is carried out on the improved ant colony algorithm. Experimental results show that the algorithm hasstrong global search ability and high search efficiency,can avoid entering the local optimal trap,and effectively improve the efficien⁃cy of fire evacuation path planning. Related Articles | Metrics

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Evacuation design problems and optimization measures for commercial complexes XUE Lian 2020, 39 (8):  1071-1074.  Abstract ( 1791 )   This article conducted an evacuation simulation of a commercial complex. By analyzing the evacuation process of its occupants, it is found that there are“bottlenecks”in the evacuation aisle, obstructions of the non- smooth corners, and clusters of“T"or“Y”shaped confluence.We adopted measures to increase the width of the bottleneck, change the shape of the contour of the aisle, and appropriately expand the width of the junction to form a buffer. The optimization results are good. In addition, the commercial complex had a low utilization rate for safe exits and stairs.The overall adjustment of the evacuation width of each exit will enable the evacuation of all safety exits to be carried out simultaneously to increase the utilization rate of the safety exits; the merging of adjacent stairs with a large difference in evacuation utilization rate will greatly increase the evacuation efficiency of the stairs. Related Articles | Metrics

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Research on emergency evacuation in large supermarket based on family group movement observation WEI Xiao-ge, YAO Hao-wei, LI Long-fei, CHEN Hong-wen, WANG Xin-feng, LI Fang-fang 2020, 39 (8):  1075-1078.  Abstract ( 1729 )   The family group movement is widespread in all kinds ofpublic places, and the emergency evacuation in buildings also includes family groups. The family group is taken as the research ob⁃ject, and the observation research was carried out in a shopping mall to get the movement characteristics. It is found that the speed of the crowd is mostly concentrated in the range of 0.8~1.2 m/s with an average value about 1.0 m/s, and the family group is more inclined to keep in the range of 0.7~1.1 m. The distance between children and adjacent adults is mostly smaller than the average distance between the group members. According to the observed data, Pathfinder software was used to simulate the evacuation in a supermarket. The results showed that the evacuation time of the corrected personnel speed is longer than the simulation result of the software default speed, and the larger the group, the longer theevacuation time of the crowd. By comparing the evacuation processes under scenarios with different exit, it is found that the entrance normally used by supermarkets plays a stronger role in emergency evacuation. Related Articles | Metrics

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Preliminary suggestions of fire safety countermeasures on common shaft pattern of smoke extraction duct and HVAC duct YIN Hang, WANG Jiong, HU Rui 2020, 39 (8):  1079-1081.  Abstract ( 1934 )   With the global trend of centralized and economical utilization of resources, the common shaft pattern of smoke extraction duct and HVAC duct is a kind of space-optimized compact arrangement. But comparing with traditional pattern, the high fire safety hazard will also result in huge potential problem for the property and life safety. In order to balance the relationship between fire safety and resource optimization in points of thermal insulation,smoke control and flame retardant, the related requirements in current fire codes and standards are analyzed based on the summarization of potential fire safety hazard of above- mentioned common shaft pattern. Some suggestions are given on the corresponding fire safety countermeasures. Related Articles | Metrics

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Analysis on fireproof height of a large-scale center of science, technology and culture CHEN Chang-hong 2020, 39 (8):  1082-1084.  Abstract ( 1726 )   Aiming at how to determine the fireproof height of slope construction in a large commercial area,taking the fire proof height of a large-scale center of science, technology and culture as the example, a comprehensive analysis of architectural features, functions, fire rescue and personnel evacuation was carried out with the principle and target from the code. Under the circumstance of ensuring the safety of whole building, the terrace on second floor was designed as for fire truck rescue site and human evacuation exit.The ridge and eaves height of large slope roof were determined reasonably, and the building height was calculated according to the code. The building was identified as multi-storey public buildings,and the classification of buildings is defined. It might provide reference and support for the fire protection design of this kind building. Related Articles | Metrics

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Effect of residence time of refuge floor on evacuation process of super high-rise building FAN Chen, CHEN Tao 2020, 39 (8):  1085-1089.  Abstract ( 1728 )   According to the different age, characteristics and gender requirements of the super high buildings, based on the evacuation experiments of the high- rise buildings in Shanghai center, record the changes of physical, blood pressure and heart rate during the long distance evacuation process, and compare the time of evacuation with the refuge layer to find out what kind of people are suitable to evacuate the floors through the stairs. Whether direct evacuation, or how long to stay in the refuge floor, a series of data analysis results will be of great help to the evacuation of super highrise buildings. Related Articles | Metrics

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Overall safety design method for fire protection of large football stadium ZHANG Zhao 2020, 39 (8):  1090-1092.  Abstract ( 1782 )   In view of the fire protection design problems of large indoor football training hall, such as large building space and large fire compartment, this paper puts forward the idea of overall fire safety design, taking targeted strengthening measures to supplement the safety problems caused by local fire protection design ex⁃ceeding the standard, so as to meet the design requirements of fire safety. Through the actual case, the feasibility of the strategy is verified by using scenario simulation analysis and computer simulation. Related Articles | Metrics

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Research on fire separation of huge underground station hall of intercity railway WEI Wen-bin, ZHAO Huan-huan, ZHAO Li-hong 2020, 39 (8):  1093-1096.  Abstract ( 1740 )   In order to make a reasonable and effective fire separation plan for the 1.2 × 104 m2 station hall fire compartment of an underground transfer station of intercity railway, fire risk of the hall was identified by the method of preliminary hazard analysis. Three different suggestions of using fire shutter, smoke curtain and firebarrier belt were proposed based on fire performance of the station.Advantages and disadvantages were summarized by analyzing compliances, safety evacuation, fire and smoke control of these fire separation schemes qualitatively. FDS and Pathfinder were used to build fire smoke and evacuation models to verify the fire safety of each scheme. The results showed that the three fire separation schemes can all meet the requirements of safe evacuation. Related Articles | Metrics

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Research on visual fire monitoring and early warning of subway construction stage based on BIM 2020, 39 (8):  1097-1100.  Abstract ( 1721 )   In view of the shortcomings of the traditional fire monitoring and early warning mode of subway projects under construction, such as low visualization degree and complicated information management, this paper proposes a visual management mode of fire monitoring and early warning combined with BIM Technology.In this way, BIM model is used as the carrier, and through the use of RevitAPI secondary development technology, the fire monitoring information is classified and integrated according to the function and order, and a "fire alarm platform" with visual early warning, data viewing, information analysis and information sharing function modules is built on Revit platform to further improve the interaction between monitoring information and BIM model, and optimize the fire monitoring early warning function visual management level, improve the safety factor of subway construction. A station of Nanning Metro Line 3 is taken as an example to analyze the practicability of this method. The practice shows that this method can improve the visual management level of fire monitoring and early warning, and has certain practical significance and application value. Related Articles | Metrics

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Development and application of fire risk assessment model for civil buildings under construction XIE Xu-chun 2020, 39 (8):  1100-1103.  Abstract ( 1768 )   In order to objectively evaluate fire risk of civil buildings under construction, this paper developed a practical fire risk assessment model. First, the paper analyzed fire characteristics and disaster factors of civil buildings under construction, and developed a comprehensive fire risk evaluation system for civil buildings under construction. Then, the Analytic Hierarchy Process was applied to determine the weight of each level, the fuzzy comprehensive evaluation method was used to make a comprehensive evaluation, and then the fire risk assessment model for civil buildings under construction at different construction stages has been built. Finally, the model was applied to evaluate the risk of a civil building under construction and to guide the rectification of fire hazard. The fire risk before and after the rectification have been compared. The evaluation results showed that the top risk factor of civil buildings under construction was the management of usage of fire and electricity, which was consistent with the actual situation. Related Articles | Metrics

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FDS-based smoke simulation of underground building fire in Xuzhou subway LI Zhi-ming, ZHOU Ran, ZHOU Xiang, ZHU Guo-qing, 2020, 39 (8):  1104-1110.  Abstract ( 1900 )   Taking the underground building of Block E of Xingshanzi project of Xuzhou subway Line 1 as the background, and considering the building's existing passive and active fire protection facilities, numerical simulation method (FDS) was used to research the reform project. The characteristics of the fire spread, temperature field, gas flow changes during the fire were analyzed in detail. The fire safety of the underground storage warehouse and maintenance warehouse was evaluated. Relevant fire safety management recommendations were made for the underground building based on the simulation results. Related Articles | Metrics

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Research on evaluation of fire rescue station construction based on GIS and ratio of response coverage ZHANG Hui, GUO Chao 2020, 39 (8):  1107-1100.  Abstract ( 1755 )   In order to scientifically determine the layout and number of urban fire rescue stations, an evaluation and calculation model based on GIS and response coverage of fire rescue stations was established. The response coverage of the existing fire rescue stations in the main urban area of Urumqi was evaluated. The basic definition, setting conditions, mathematical description, evaluation methods and judgment criteria of the evaluation calculation model was introduced. The road network map of Urumqi and the distribution map of 21 urban fire rescue stations were vectorized.The response coverage, cross response coverage and average driving time were calculated. The evaluation calculation shows that the response coverage rate of the fire rescue station in the main urban area in the first driving period is 28.14%; the cross response coverage rate is 23.33% ; and the average driving time is 7.7 min. The layout of the existing fire rescue stations in the main urban area of Urumqi is basically reasonable and the number is seriously insufficient. Related Articles | Metrics

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Multi-exit building emergency evacuation model based on the view of most unfavorable point WANG Jian-guo, WANG Jing-wei, YIN-Xiong 2020, 39 (8):  1111-1114.  Abstract ( 1732 )   In order to effectively evaluate the emergency evacuation capacity of multi-exit buildings, the evacuation process is analyzed from the view of the most unfavorable point of each evacuation path. Firstly, established the governing equations of four periods including pre- action time, travel time, delayed time, and walking time, as well as the algorithm for calculating the travel time of people at an unfavorable point, then constructed a mathematical model for group evacuation of a multi- exit building. Taking a subway transfer station in Xi'an as a prototype, the evacuation time is calculated by mathematical model and simulation model respectively.The results show that during the evacuation process, travel time at the most unfavorable point in a evacuation of a certain evacuation structure is not only related to the evacuation capacity of the structure, but also related to other evacuation structure before passing the evacuation structure, and the number of people to be evacuated. The evacuation capacity of the stairs and the speed of people moving on the stairs are positively related to the width of the stairs.It has a negative correlation with the thickness and width of the human body. The calculation time error with the simulation model is only 1.47%. Related Articles | Metrics

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Numerical simulation study on fire of typical UHV converter transformer ZHANG Jia-qing, LI Guo-hui, WANG Ya-long, LI Chang-hai, SHANG Feng-ju, LU Shou-xiang 2020, 39 (8):  1115-1120.  Abstract ( 1821 )   Based on literature review and analysis of accident data,the structural characteristics and accident conditions of UHV converter transformer were elaborated. By means of CFD numerical simulation, according to the oil states, boundary conditions and environmental conditions of typical accident conditions, the occurrence and development process of transformer fire in typical UHV converter station were studied based on 5 scenarios. The combustion form, heat release rate and temperature around fire source of typical transformer fire were analyzed. The influence of the temperature of the outer wall of the valve chamber on the valve chamber were obtained. The characteristics of slow temperature rise and low temperature in the early stage of fire should be considered during the design of the detachable Box- in roof. In order to create favorable conditions for the extinction of the converter fire source,the sealing of the valve hall and the Box- in noise reduction plate should not be damaged at fire, and the lower 3 rows of cooling fans should be closed actively to prevent air from flowing in. The front cooling fan hole of the converter should be completely closed to prevent air from entering when the valve hall plugging is damaged. Related Articles | Metrics

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Numerical simulation on cable fire in T-shaped underground pipe gallery AN Wei-guang, WANG Tao, LIANG Kai, ZHU Guo-qing, 2020, 39 (8):  1120-1123.  Abstract ( 1784 )   This paper focuses on the T- shaped underground pipe gallery. FDS software was used to simulate the spread of cable fire in the pipe gallery under different fire source locations and wind speed conditions. The temperature field of the pipe gallery and the spread behavior of smoke after the fire were analyzed. The fire hazards at different locations in the T-shaped pipe gallery were sorted.When the wind speed inside the pipe corridor is 1.5 m/s and the cable is in a stable burning period, the height of the smoke layer at the intersection is the lowest. The characteristics of smoke at the intersection of T-shaped pipe gallery were obtained. The results of this work can provide some reference for fire safety design of Tshaped underground pipe gallery. Related Articles | Metrics

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Effectiveness evaluation of transformer fire extinguishing system of UHV converter station based on simulation experiments WANG Shou-jiang, CHEN Qin-pei 2020, 39 (8):  1124-1127.  Abstract ( 1962 )   In order to build an effective UHV converter station transformer automatic fire protection system, a comprehensive analysis of the characteristics of this type of transformer fire is carried out, and based on the method of solid fire simulation experiments, the effectiveness of the high- pressure water mist system and the water mist turbofan gun system for fire extinguishing is emphasized. The experimental results show that both systems have efficient fire extinguishing performance, and the lateral sprinkler can effectively improve the fire extinguishing efficiency of the highpressure water mist system；The sequence of fire extinguishing actions of the turbofan gun system should be from top to bottom, and continuous cooling after spraying to prevent reignition . Related Articles | Metrics

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Improved design of transformer fire extinguishing system based on case analysis LI Dian-chen, LIANG Ge 2020, 39 (8):  1127-1129.  Abstract ( 1725 )   Through the investigation of actual fire cases, this paper summarizes the experience and lessons of transformer fire at home and abroad, and analyzes the causes of transformer fire and the weak parts of pressure bearing. The paper points out the design and construction technical defects of transformer fire extinguishing system, and carries out the fire extinguishing test of transformer fire,such as shielding fire, internal and external fire, compound fire,etc., which is compared with the fire extinguishing effect of commonly- used transformer fire extinguishing system. Some suggestions are put forward, such as improving the technical standard of fire protection, perfecting the design, construction, maintenance and strengthening the fire safety management. Related Articles | Metrics

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Spraying characteristics of single nozzle and fire extinguishing test of fixed compressed air foam system ZHAO Sen-lin, XIONG Mu-wen, WEN Pei, WANG Guan-jian, HAN Jiao, SHI Xiang-jian, GAO Xu-hui, LIN Yu 2020, 39 (8):  1130-1134.  Abstract ( 1843 )   A single nozzle spray of compressed air foam and pure water experiments have been conducted with of five typical types of nozzles. The density distribution of the spray medium at the bottom surface and the 25% liquid separation time of the sprayed foam are compared and analyzed. It is found that the structural type and flow parameters of the nozzles will affect the foaming characteristics of the foam. The internal core of the nozzles will reduce the foam stability; the uniformity of the bottom surface of the suspended nozzles is relatively good, while the turbulent nozzle and two types of seven- hole nozzles are relatively uniform, besides, the uniformity of the bottom surface distribution of the suspended nozzle and the gas nozzle under higher pressure and flow conditions is reduced; Meanwhile, nozzles selection of the compressed air foam system can refer to the corresponding nozzle's water spray characteristics. Based on the research, optimal performance nozzle was selected, the fire model was established, and full- scale transformer hot oil fire test of the fixed compressed air foam system was carried out to verify the adaptability of the nozzle and the system. Related Articles | Metrics

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Analysis of improvement strategies for the fire extinguishing systems of UHV transformers CHEN Bao-hui, LI Bo, WU Chuan-ping, LIU Yu, ZHOU Tian-nian 2020, 39 (8):  1134-1137.  Abstract ( 1918 )   The present fixed fire- fighting technologies of the UHV converter station/substation transformers were analyzed. Focused on improvement strategies for the fire extinguishing systems ofUHV transformers including water spray extinguishing system, foam spray extinguishing system and compressed air foam extinguishing system comparisons were made on fire extinguishing efficiency, explosion proof performance, safety and stability. It provided guidance for the fixed fire protection facilities of UHV converter station/substation transformer. Related Articles | Metrics

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Fire accident characteristics and firefighting solutions of large converter transformer CHEN Tao, ZHAO Li-zeng, FU Xue-cheng, ZHANG Jia-qing, WANG Qing, HU Cheng, BAO Zhi-ming, LI Bao-li, LI Guo-hui 2020, 39 (8):  1138-1141.  Abstract ( 1867 )   The problems of existing fire-fighting systems were clarified based on the analysis on the fire causes and high- risk area of large converter transformer, the influencing factors and development process of large transformer explosion and fire, as well as the characteristics of explosion and fire accidents of transformer high voltage (HV) bushing. A new fixed fire extinguishing system was also proposed. The results showed that HV bushing is a high fire risk area of large oil immersed transformer. The tank will explode when the energy of internal fault of transformer reaches a certain value. Whether a fire can be caused after a transformer explosion is closely related to whether the mixed gas leaked to the air reaches the explosion limit and whether there is enough ignition energy. The principle is that fire extinguishing based on fixed fire extinguishing system should be adhered to. It is recommended to use the new compressed air foamsprinkler system without sprinkler head and branch pipe. Related Articles | Metrics

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Design and implementation of combined electrical fire detector based on NB-IoT and MCU JIANG Jian-feng, YANG Liu-fang, CAO Wei-jia, LIAO You-wei 2020, 39 (8):  1142-1144.  Abstract ( 1759 )   In order to prevent electrical fire accidents, a combined electrical fire detector is designed and developed with STM32F103VCT6 as the main controller and NB-IoT as the communication module. The detector collects fault information such as short circuit, open circuit, over-voltage, under voltage, over-current, temperature abnormality and leakage of electric equipment and transmission lines, will immediately send out an audible and visual alarm and display its fault information on the screen, and simultaneously upload the information to the Internet of things platform, push the fault information to the user in time through the computer and mobile phone, and conduct remote supervision on it.The test results show that the electrical fire detector is sensitive,stable and the equipment operates stably. Related Articles | Metrics

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Research on the application of UAV Detection Function in incidents of hazardous chemicals WU Li-zhi, CUI Yan-chen, ZHU Hong-wei, XIA Deng-you 2020, 39 (8):  1145-1148.  Abstract ( 1775 )   In order to improve the detection function of the UAV at disaster site, this paper starts with the analysis of the problems existing in the detection of the drone, uses CFD simulation to observe the wind field condition of the drone hover state, and formulates the installation location of the UAV detection module. Taking ammonia as an example, combined with the basic information of the test site, the numerical simulation scheme of gas diffusion isconstructed. By comparing the data information of static detection instrument and UAV module, the scientific nature of the detection and collection data of the drone is verified, and the detection method of "UAV detection previously , CFD prediction later on" is proposed by comparing the detection data of the unmanned aerial module with the simulation data of the aircraft carrier module. The research provides some theoretical and practical guidance for the scientific detection of UAV at disaster sites. Related Articles | Metrics

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Water supply test and application analysis of ultra-high-pressure fire pump in super high-rise buildings ZHANG Ming-zhen, DUAN Jiang-zhong, KUANG Kai-qian, LU Yi-wen, DANG Jie 2020, 39 (8):  1149-1151.  Abstract ( 1793 )   Fire water supply is the key to firefighting of super highrise buildings. The practical application of an ultra-high-pressure fire pump in a super high- rise building was tested to obtain key technical parameters of pressure and flow. The test results showed that the water supply height is 303 m, the maximum pressure of the water pump is 7.5 MPa, the water supply flow rate is 26.9 L/s, the maximum flow rate is 44.4 L/s. The theoretical water supply height is over 600 m, which meets the actual firefighting needs.The system has the advantages of high pressure, large flow and high reliability. It can respond to the fire water supply problem of super high-rise buildings effectively Related Articles | Metrics

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Research on the effect of heat treatment on thermal runaway characteristics of lithium-ion batteries SUN Jian, HE Yuan-hua, XIE Song 2020, 39 (8):  1153-1155.  Abstract ( 1746 )   In order to explore the effect of external high temperature on the thermal runaway characteristics of lithium-ion batteries with different charged states,18650 lithium- ion batteries with three charged states were heated to 80 ℃ and 100 ℃ respectively. After standing at room temperature for 24 hours, the thermal runaway was made by hot runner heating coil, and the characteristic parameters such as temperature and voltage were analyzed. The results show that at the same heat treatment temperature, the higher the charge state of lithium- ion battery, the more severe the thermal runaway phenomenon, the higher the thermal runaway temperature, the earlier the voltage drop time. In the same charged state, the thermal runaway phenomenon of lithium- ion battery heat- treated to 80 ℃ is more severe, the thermal runaway temperature is higher, but the voltage drop time is later. The experimental results can provide a theoretical basis for the safe transportation, storage and application of lithium-ion batteries. Related Articles | Metrics

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Research on early warning parameters of thermal runaway of lithium ion battery for energy storage power station GUO Dong-liang, LIU Yang, XIAO Peng, SUN Lei, TAO Feng-bo 2020, 39 (8):  1156-1159.  Abstract ( 1905 )   The variation of characteristic parameters such as the voltage, surface temperature, and released gas concentration of lithium iron phosphate batteries for energy storage under over⁃charge condition were discussed. The thermal runaway mechanism, development process and early warning threshold were analyzed. The experimental results showed that overcharging can lead to a series of exothermic chemical reactions inside the battery,which causes increase in temperature and voltage, accompanied by a large amount of combustible gas production.The H2 is the highest in content in the mixed gas and is detected by the gas detector first. The recommended alarm ranges of battery voltage, surface temperature and H2 concentration are 4.8~6.6 V, 60~116 ℃ and 20~50mg/L, respectively. Related Articles | Metrics

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Influence of environment systemon the fire hazard of lithium-ion battery underthermal runaway conditions GUO Jun, HE Yuan-hua, WANG Hai-bin, CHEN Xian-tao 2020, 39 (8):  1160-1164.  Abstract ( 1787 )   Taking the 21700- type ternary lithium- ion battery as research project,under the environment of air,nitrogen and water mist,the surface temperature of lithium- ion battery and the concentration of escaping gas were monitored onine under the condition of thermal runaway to explore heat transfer and thermal runaway fire expansion between lithium- ion batteries.The results showed that different environment systems have significant influence on thermal runaway fire behavior of lithium-ion battery. Thermal runaway of lithium- ion battery can't be controlled effectively when experimental space is filled with the high concentration nitrogen. However,due to the decrease of oxygen concentration, the thermal runaway second burning stage doesn't occur,which can reduce the risk of fire spread and prolong the response time of thermal runaway effectively. The peak volume fraction of CO in the nitrogen environment is 2 049×10- 6,which are 154.6% and 180.0% of that in air and water mist environments. Under the misty environment,the mist converges at the positive electrode,which will easily reduce the working efficiency of safety valve. Once the internal pressure of the lithium-ion battery is too high,the more serious explosion will occur. In the transportation,storage and application of lithium- ion batteries,excessive humidity should be avoided. The occurrence of thermal runaway can be prevented by replacing the environmental atmosphere and improving the heat dissipation capacity contrapuntally,to strengthen the safety protection of lithiumion battery. Related Articles | Metrics

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Study on the characteristics of thermal runaway gas released from lithium-ion batteries in air transport GUO Chao-chao, ZHAO Hui-bing 2020, 39 (8):  1164-1167.  Abstract ( 1719 )   In order to study the risk of thermal runaway of lithium battery in air transportation quantitatively and provide theoretical guidance for its mass transportation,thermal runaway experiments were carried out on lithium batteries under different states of charge and negative pressure to determine the gas release characteristics of lithium battery under different conditions. GC-MS was used to determine the gas composition in different SOC and negative pressure environment, and gas chromatograph was used to determine the content of each component of the gas released from the thermal runaway lithium ion battery under different conditions.The experimental results showed that different charge states have significant effect on the amount of gas released when the lithium battery initially exploded. When the state of charge is 10% or less,the amount of gas released from the lithium battery and the initial explosion temperature are higher. Different SOC has little influence on the composition of the gas, but have great influence on the content of the components. The amount of gas increases with the increase of negative pressure. Related Articles | Metrics

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Fire extinguishing effect of heptafluoropropane on fire of lithium iron phosphate energy storage batteries ZHANG Jian, LI Jian-yong, ZHANG Ming-jie, TIAN Yan-hong, HAN Hui, YANG Kai, CHI Ming-sheng 2020, 39 (8):  1168-1181.  Abstract ( 2198 )   Heptafluoropropane was used as extinguishing agent to research the fire extinguishing effect on fire of lithium iron phosphate energy storage battery under different injection modes. It is found that all modes of injection can extinguish open flames within 8s, but the extinguishing effect is different. When heptafluoropropane is sprayed vertically, it only takes 2 s to extinguish open flames, and the instantaneous cooling rate can reach 43 ℃/s at most. The suppression time of reburning is long, the duration of temperature rising and the duration of smoking are short. The extinguishing agent nozzle should coverup of the batterydirectly to maximize the extinguishing effect of heptafluoropropane of injection mode. Related Articles | Metrics

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Study of the direct fire loss of more than 10 million Yuan fire statistics from 2007 to 2017 SI Ge 2020, 39 (8):  1171-1174.  Abstract ( 1728 )   Using Spearman rank correlation coefficient, the correlation between the fire with direct property loss more than 10 million Yuan by fire authority or fire with property insurance compensation more than 10 million Yuan by insurance company from 2007 to 2017 with GDP and permanent population was analyzed. It is suggested that the statistical system and working mechanism of fire direct property loss should be reformed and improved. Data sharing with relevant departments should be strengthened. Big data and blockchain technology should be applied to provide scientific basis for decision-making of fire control. Related Articles | Metrics

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Thoughts on standardized management of fire safety in industrial units YE Ying 2020, 39 (8):  1174-1177.  Abstract ( 1689 )   In order to promote the standardized management of fire safety in industrial units, this paper analyzes the current situation of the standardized management of fire safety in industrial units in Shanghai. In light of relevant national laws and regulations, Industry Standards and document requirements, in view of the major problems existing in the implementation of standardized management of fire safety by industry units and the major problems existing in the promotion of supervision by fire departments, the improvement countermeasures and suggestions are put forward to promote the standardization management of fire safety in the industry.The fire safety management ability of industrial units can be improved by promoting the construction of fire control system standards, strengthening the supervision of fire control standards,making fire control management standards scientifically and developing fire control standard information system. Related Articles | Metrics

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Exploration on undergraduate education of new-type aviation emergency rescue command talents QI Fang-zhong 2020, 39 (8):  1178-1181.  Abstract ( 1737 )   Based on the task expansion and development trend of the aviation emergency rescue, this paper presented a conception of new- type aviation emergency rescue command talents who integrated abilities of command and management, actual rescue combat and staff assistance, discussed the necessity of the new- type talent education, constructed the ability and quality structure model of the new-type talents, advanced some tactics for talent cultivation in colleges from three aspects of setting up relevant majors, innovating educational methods, and strengthening security, in order to provide countermeasures and suggestions of solving the current shortage problem of the aviation emergency rescue command talents. Related Articles | Metrics

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Fire investigation of ship deflagration caused by spent hydrotreating catalyst LIANG Guo-fu, WANG Xin 2020, 39 (8):  1182-1185.  Abstract ( 1709 )   The fire investigation of a ship container cargo deflagration caused by spent hydrotreating catalysis was analyzed. By video analysis, personnel description, trace of the scene, the container where the deflagration firstly happened was confirmed. By XRD, XRF, the cargo was identified as spent hydrotreating catalyst. By analysis method such as gas chromatography mass spectrometry and microcalorimetry, the reason of the deflagration was determined. Related Articles | Metrics

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Effects of convectional ventilation on determination the fire origin based on fire cases SU Wen-wei, SONG Zhen-fang 2020, 39 (8):  1186-1189.  Abstract ( 1712 )   The basic situation and field investigation process of a fire case were introduced. The typical fire trace characteristics under the condition of convection ventilation were analyzed combined with case study. The preliminary analysis was carried outaccording to the site investigation. The mobile phone video of the first alarm person and on- site personnel was accessed. Combing with the results of inquiry and electrical inspection and residue detection, inviting fire accident investigation experts to assist in the investigation, the seat of fire was determined. The typical interference trace characteristics caused by convection ventilation are summarized combined with the case and fire investigation experience, and methods and countermeasures of fire location identification were discussed from 5 aspects. Related Articles | Metrics