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19 July 2024, Volume 43 Issue 7 Previous Issue   

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Numerical simulation study on hydrogen explosion characteristics in open spaces Guan Wenling1, Li Mofan1, Dong Chengjie1, Ren Changxing2,3,4 2024, 43 (7):  0-951.  Abstract ( 28 )   In order to study the hazards of open hydrogen explosion, a three-dimensional numerical model of open hydrogen-air explosion was established based on Fluent fluid dynamics calculation software. On this basis, cubic premixed hydrogen-air explosion with side lengths of 0.5, 1.0, 2.0 m and 3.0 m was simulated and analyzed, and the numerical simulation results were compared with the explosion intensity grades of TNO multi-energy method and BST method. The results show that the flame propagation distance is about 2 times of the initial hydrogen radius. The dimensionless distance of the location of the maximum explosion pressure is approximately linear with the initial radius of the gas cloud. The choice of explosion intensity grade of TNO multi-energy method and BST method should increase with the increase of initial size of gas cloud. Related Articles | Metrics

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Measurement and simulation research on smoke control in the underground single crossover distribution section of rail transit Liu Kai1,2 2024, 43 (7):  0-970.  Abstract ( 21 )   In order to clarify the smoke control effects of different smoke exhaust design schemes in the single crossover distribution section, a single crossover distribution section of a certain subway line was selected. Through on-site measurement and smoke flow numerical simulation analysis, the factors affecting the overall smoke exhaust capacity and airflow organization distribution of the tunnel section were obtained. The results show that under the single crossover form, the smoke exhaust capacity of the tunnel ventilation system mainly depends on the TVF fan. In the case of no jet fan and only relying on the TVF fan, adopting a 2-supply 2-row mode can meet the requirements of the cross-sectional wind speed in the fire section, and there is no phenomenon of smoke flow crossing the crossover line; The number of TVF units activated significantly increases the wind speed in the fire zone, but using the 4-to-4 exhaust mode will cause smoke to pass through the station. Related Articles | Metrics

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Development and application of high power density portable submersible electric pump emergency drainage rescue vehicle Qiu Hiudong1, Chen Xiaoqing2, Wang Haifeng3, Long Yun4 2024, 43 (7):  0-981.  Abstract ( 26 )   With the frequent occurrence of urban waterlogging and the increasing severity of flood disasters in China, the importance of emergency drainage and rescue equipment is becoming increasingly prominent. To meet this demand, the development of emergency rescue vehicles and high-power density submersible pumps are summarized, and a new type of high-flow submersible electric pump is developed, which is driven by a permanent magnet synchronous motor, features high power density, large displacement, and lightweight portability. In order to improve the comprehensive performance of the submersible pump, a combination of numerical simulation and experimental verification methods is employed, to investigate the internal flow characteristics of the submersible pump. With the SST k-ω turbulence model as the calculation model, various flow rates (0.6Q, 0.8Q, 0.9Q, 1.0Q, 1.1Q, and 1.2Q) are selected; Representative velocity distribution maps are selected to compare and analyze the internal flow structures and their variations under different flow rates;The pressure load curves of the impeller blades and guide vanes are extracted. The application of the high-power density portable submersible pump in this emergency drainage and rescue vehicle has broad prospects and aligns with the development trend of the emergency drainage industry. The research in this study contributes to improving the hydraulic performance of submersible pumps, thereby enhancing urban disaster prevention and mitigation capabilities. Related Articles | Metrics

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Research on the design parameters of mobile high-pressure water mist fire extinguishing device in cultural relic buildings Zhang Zilong1, Liu Fang1, Li Hongwen2, Qian Yufeng2 2024, 43 (7):  0-996.  Abstract ( 19 )   In order to investigate the design parameters of a mobile high-pressure water mist fire extinguishing device in cultural heritage buildings, a 6A wood pile fire test platform was set up to study the suitable jet flow rate and distance for this device to handle large-scale fires under different jet distances and modes. The Fire Dynamics Simulator (FDS) was used to simulate a historical building in Beijing as a model, validating and supplementing the design parameters of the mobile high-pressure water mist fire extinguishing device from aspects such as jet intensity, jet distance, jet timing, and atomization particle size. The results show that the jet intensity can be set at 4.4~6.6 L/（min.m2）; the jet distance can be set to 5 m. A close jet strategy is used whenever possible; the fire extinguishing timing should be as early as possible, at least within 300 s after the fire starts; the choice of atomized particle size needs to be weighed on a case-by-case basis. Related Articles | Metrics

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Analysis of influencing factors of the landing points selection for forest fire rescue Pan Weijun1, Huang Yuanjing1, Yang Zhaoxi2, Li Binxi2 2024, 43 (7):  0-1027.  Abstract ( 19 )   In order to improve the efficiency of forest fire general aviation emergency rescue, an improved DEMATEL-ISM method was proposed to analyze the influencing factors of the selection of take-off and landing points. Firstly, based on grounded theory, a system of influencing factors for the selection of take-off and landing points for general aviation emergency rescue in forest fires is established. Then, fuzzy set theory is introduced to eliminate the subjectivity of expert rating in DEMATEL-ISM method. Based on the analysis of the causal attribute and the degree of influence among the influencing factors in the selection of forest fire take-off and landing points, five important factors, two fundamental factors,3 direct factors, and 10 indirect factors were determined, and relevant suggestions for the selection of take-off and landing points were put forward. The study results can speed up the decision speed of the selection of take-off and landing points for forest fires, and provide theoretical basis and scientific reference for improving the efficiency of forest fire general aviation emergency rescue. Related Articles | Metrics

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Analysis of electric vehicle fire accidents and exploration of fire protection measures Wan Shaojie 2024, 43 (7):  0-1042.  Abstract ( 17 )   By conducting a statistical analysis of fire incidents involving electric vehicles, this article elucidates the mechanisms behind those occurrences, and proposes preventive and control measures over production, sales, usage, maintenance, and recycling of electric vehicles five aspects based on the three major factors that cause EV fires-internal battery short-circuiting, external battery short-circuiting, and overcharging or over-discharging of the battery, alongside the characteristics of those incidents such as rapid spread, high risk, difficulty in extinguishing, and susceptibility to reignition,aiming to offer insights for firefighting and rescue operations involving electric vehicles. Related Articles | Metrics

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Thermal runaway analysis and liquid nitrogen suppression effects in lithium iron phosphate batteries for energy storage applications Shi Bobo1, Wang Yuheng1, Wang Zhi1, Li Zhihua2 2024, 43 (7):  907-912.  Abstract ( 74 )   Lithium-ion batteries are susceptible to thermal runaway when exposed to external environmental influences during operation. This phenomenon, inherently unpredictable, can lead to severe and challenging-to-mitigate consequences, particularly as the State of Charge (SOC) markedly influences the onset and severity of thermal runaway. In this context, our investigation delves into the thermal runaway behaviors of lithium-ion batteries across a spectrum of SOC conditions, employing liquid nitrogen injection for cooling within a controlled environment. Moreover, this research extends to evaluating the impact of thermal insulation on battery enclosures, aiming to assess its contribution to enhancing the efficacy of liquid nitrogen cooling and the overall suppression capabilities against thermal runaway. The study elucidates a direct correlation between increased SOC and the magnitude of fire incidents, mass loss, and carbon monoxide generation during thermal runaway incidents. It was observed that the critical temperature threshold for initiating thermal runaway decreases with an elevation in SOC, whereas the peak temperature experienced during thermal runaway escalates. The duration to reach thermal runaway, time to peak temperature, and the differential in characteristic timescales exhibit a proportional relationship with SOC. Implementing thermal insulation treatments on battery enclosures demonstrated a notable extension in the cooling effects of liquid nitrogen, maintaining a prolonged cooling action on batteries undergoing thermal runaway. This significantly enhanced cooling duration effectively contributes to strategies aimed at delaying or even preventing thermal runaway, offering a viable approach to mitigating the risks associated with lithium-ion battery operations. Related Articles | Metrics

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Experimental study on the influence of ground effect on the merging characteristics of dual flame sources in road tunnels Peng Wei1,2, Zhang Wei2, Xie Qi2, Zhang Shaojie2 2024, 43 (7):  913-918.  Abstract ( 35 )   In order to investigate the influence of the ground effect on the flame merging characteristics of dual ignition sources when a double fire occurs in a naturally ventilated tunnel, a series of experiments were carried out using a 1:10 small-size tunnel model. The focus was to investigate the effect of fire source spacing on the flame merging probability and the height of the flame merging point when the surface of the dual fire sources is flush with the tunnel floor. The results show that: fire smoke flows out of the openings at both ends of the tunnel, and the wind speed generated by the fresh air supplemented from both ends of the tunnel causes the flames to still tilt towards each other when the fire sources are more widely spaced, and the flame tilting angle is about 10° when the spacing is sufficiently large. A dimensionless quantity is introduced to represent the law that the flame merging probability varies with the change of fire source spacing and heat release rate. In addition, the experimental data in this paper are also compared with the previous work, and it is found that the ground effect contributes greatly to the flame merging behavior of dual fire sources in a longitudinal tunnel arrangement. The relationship equation between the ratio of the height of the flame merging point to the tunnel height and the modified dimensionless heat release rate is also given. Related Articles | Metrics

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A review on the complexity mechanism of road transport accidents of hazardous chemicals Luo Cheng1, Han Dong2, Jiang Zao1, Li Cong1, Sun Jian1, Lu Yani3 2024, 43 (7):  919-931.  Abstract ( 46 )   To explore the research status of the complexity mechanism of hazardous chemical road transportation accidents, a new literature classification method based on accident risk characteristics is proposed. This method comprehensively evaluates existing literature from four aspects: complexity and complex system characteristics, accident causation theory, accident risk evolution process, and accident risk coupling consequences. The analysis show that in the past two decades, research related has developed rapidly, with the most mature research on accident causation theory. The evolution of accident risk and the coupling of accident risk are gradually becoming the focus of scholars' attention; Most research focused on the macro level, with relatively little research on the micro level. A complete theory hasn't been formed on how risks and energy are transmitted and transformed at different levels, nor has the process and laws of the interaction and evolution of internal risk factors within the system been revealed; Based on new classification methods, it has been found that most studies use single objective solving or multi-objective optimization models, which fail to fully consider the dynamic risk characteristics and time-varying effects of transportation processes. Accident uncertainty analysis based on accident consequences and environmental pollution risks may be a future hotspot. Related Articles | Metrics

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Research on three-dimensional deformation monitoring of steel portal frames under fire based on ground-based interferometric radar Zhang Hao1,2, Wen Jinglin1, Yang Xiaolin1, Ma Haitao1, Wang Yiran3 2024, 43 (7):  932-936.  Abstract ( 37 )   The collapse of building fires poses a serious threat to the safety of personnel. Research has shown that ground interference radar can be used for micro deformation monitoring and early warning of portal steel frames under fires. However, due to the fact that radar can only obtain deformation in the direction of the target line of sight, it is difficult to meet the multi-dimensional data requirements of early warning models. Therefore, it is urgent to study the three-dimensional deformation monitoring of building structural targets. On the basis of discussing the microwave signal model of the system, this article proposes a radar equivalent phase center estimation method based on distributed target imaging information, which achieves iterative optimization of the target's three-dimensional transformation matrix. Then, a scaled double span steel frame fire test is carried out to obtain the three-dimensional deformation component of the structural target under local coordinate system, and the monitoring results are compared with those of traditional wire displacement meters. The experimental results show that the combination monitoring of multiple ground-based interferometric radars can effectively obtain the three-dimensional deformation components of structural targets in real fire scenarios. The monitoring results conform to the deformation laws of existing portal steel frame structures under fire, and can provide effective data support for building collapse warning under fire. Related Articles | Metrics

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Thermal runaway multi-data fusion detection of lithium battery based on Transformer neural network Ding Mutao, Guo shiwei, Shan zhilin, Zhang Qixing 2024, 43 (7):  937-945.  Abstract ( 51 )   In order to meet the demand for efficient and accurate detection of lithium ion battery thermal runaway, this study designed a lithium battery thermal runaway experimental platform. STM32F103ZET6 single chip microcomputer was used to connect four sensors such as carbon monoxide, carbon dioxide, hydrogen and NTC to collect characteristic parameters in real time. At the same time, PyroSim is used to simulate the experimental environment and generate high-quality simulation data to supplement the experimental data. Based on the pytorch platform, we designed a Transformer neural network that can output the normal, early warning and thermal runaway states of lithium batteries. By using experimental data and simulation data for training, we successfully achieved fusion detection of thermal runaway data of lithium batteries, and verified the effectiveness of the algorithm. Related Articles | Metrics

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Experimental analysis and research on the combustion supporting characteristics of sodium chlorite Shi Yunxian 2024, 43 (7):  952-958.  Abstract ( 32 )   In order to study fire prevention measures for sodium chlorite, firstly, the combustion-supporting characteristics of sodium chlorite under different ignition sources and humidity conditions were studied through simulation experiments. Secondly, ion chromatography is employed to measure the content of ClO_2^ in the combustion residues, thereby quantitatively analyzing the combustion-supporting effect of sodium chlorite. Finally, fire prevention design strategies for sodium chlorite are formulated based on the investigations above. The results show that when a cigarette butt is used as an ignition source, sodium chlorite can cause most of combustible materials to burn, with the greatest pronounced effect observed on sulfur-containing substances and potassium sorbate. When mechanical sparks are used as ignition sources, sodium chlorite can promote the combustion of sulfur-containing substances, preservatives as well as porous combustibles, but it is difficult to promote the combustion of fabrics with dense structure. When an incandescent light is used as an ignition source, sodium chlorite can only facilitate the combustion of a few strong reducing agents. However, when an electric heater is used as an ignition source, sodium chlorite fails to cause the combustion of any of the experimental samples. In addition, when a drop of water is used as an ignition source, sodium chlorite can cause the combustion of sulfur-containing organic compounds or reductive sulfur-containing substance. Samples mixed with sulfur and sodium sulfide can even undergo deflagration under humidity conditions ranging from 33.1% to 97.6%. This paper can provide some reference for fire prevention requirements in production, storage and transportation of sodium chlorite. Related Articles | Metrics

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Experimental study on fire spread between timber structure buildings Peng Lei1, Qiu Peifang2,3,4,Ou Jiajia5 2024, 43 (7):  959-966.  Abstract ( 34 )   A timber frame structure was set up to conduct fire test studies on the factors affecting the fire spread between timber structure buildings. The study considered variables such as fire load density, size of exterior wall openings, combustibility of exterior wall materials, and horizontal spacing between two buildings. The results indicate that increasing the opening area of the external wall would significantly enhance the radiative heat flux on the target wall under identical fire load densities. Similarly, increasing the fire load density in the burning room would also amplify the radiative heat flux on the target wall under consistent opening conditions. Once ignition occurred in the exterior wall of the burning room, the target wall would be exposed to the combined radiation from the room opening and the external flame in the exterior wall, and this would potentially escalate fire spreading risks for the target wall. In the tested fire scenarios with a 6 m fire spacing, the radiative heat flux values on the target wall remain below 10 kW/m2, which did not pose a risk for fire spread between buildings due to radiation. These research results provide supportive data for quantitatively analyzing various factors' influence on building-to-building fire spread and aid in determining appropriate fire spacing between builds. Related Articles | Metrics

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Full-scale experimental study on the burning and spreading characteristics of baggage fire in high-speed railway waiting hall Ou Chen1,2, Xiao Niqi1,2, Zhang Ning1,2, Zhao Jiaming1,2 2024, 43 (7):  971-975.  Abstract ( 39 )   In order to provide a reference for the fire safety design of the waiting hall of high-speed railway, a full-scale burning test for baggage fire was carried out in the partial area of a waiting hall with 5 MW calorimeter. Typical baggage combustible materials such as 50 cm×30 cm×20 cm hand luggages, woven bags and backpack (books, notebooks, pen cases, pens and power banks) were used to form baggage stacks. The variation trend of characteristic parameters such as heat release rate, temperature and radiant heat flow were monitored and recorded. Results show that the burning of the full-scale baggage fire presents obvious stage characteristics. The temperature rise and heat release rate increase the fastest in the development stage, and the variation trend of heat release rate in the growth stage of baggage fire is in good agreement with the t2 fast fire. The maximum heat release rate of baggage fire reaches 1 004 kW and the maximum temperature is close to 640 oC. In current full-scale baggage stack fire, the combustibles 1 m away from the burning baggage stack were not ignited, but softened and melted. To some extent, an interval distance of 1 m can effectively avoid the continuous spread of open flames in luggage stacks. The 9 m isolation belt can effectively play the role of fire and heat insulation, and the temperature rise and radiant heat flow at the location 9 m away from burning luggage stack are not obvious. Related Articles | Metrics

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Experimental study on the attitude of the helicopter fire fighting bucket Xie Jiayu1, Zhu Yanan2,3,4, Ruan Tao2,3,4, Liang Runjie2,3,4, Li Jinpeng2,3,4 2024, 43 (7):  982-989.  Abstract ( 44 )   To quantitatively study the influence of the posture of the helicopter fire bucket on the accuracy of watering and the stability of the helicopter during the firefighting process, a helicopter fire bucket posture experimental platform was constructed to design and carry out scaled size tests of the fire bucket. Conduct helicopter fire bucket swing tests considering four factors: incoming flow velocity, mass, rope length, and installation of tail fins. Use a data acquisition system with attitude sensors and tension sensors as the core to collect the attitude angle of the fire bucket and the vertical force of the rope during the experiment. The results show that the range of attitude angle changes is 7.85°, 20.40°, and 34.84° when the inflow velocity is 8, 16, and 24 m/s. The difference between the maximum vertical force on the rope and its own gravity is 0.18, 1.13, and 2.29 N; When the mass is 301, 271, and 241 g, the range of attitude angle changes is 17.45°, 20.40°, and 38.27°. The difference between the maximum vertical force on the rope and its own gravity is 0.95, 1.13, and 1.17 N; When the length of the rope is 100, 150, and 200 mm, the range of attitude angle changes is 22.41°, 20.40° and 19.61°. The difference between the maximum vertical force of the rope and its own gravity is 1.93, 1.79, and 1.56 N; Orthogonal experimental analysis shows that the degree of influence for different working conditions in descending order is inflow velocity>rope length>mass, with inflow velocity having a significant impact on the experimental results (P<0.01); The attitude angle variation range of helicopter fire buckets with or without tail fins is 15.78° and 55.76°, and the difference between the maximum vertical force on the rope and its own gravity is 0.64 N and 1.06 N. In summary, reducing the inflow velocity, increasing the mass of the fire bucket, increasing the length of the rope, and installing tail fins can effectively reduce the amplitude of the posture change of the fire bucket and improve the uniformity of vertical force, thereby optimizing the sprinkler accuracy and helicopter stability. Related Articles | Metrics

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Research on fire extinguishing efficiency of a fire extinguishing device for electric vehicles Xia Xinsheng 2024, 43 (7):  997-1000.  Abstract ( 30 )   In order to study the rapid extinguishing of electric vehicle fires, the author designed an electric vehicle fire extinguishing device based on practical work experience. The performance of the extinguishing device was tested by different water pressures of the fire truck. Select electric vehicles for combustion tests and observe the effectiveness of the firefighting device in extinguishing electric vehicles. The results show that the electric vehicle fire extinguishing device has significantly better water flow rate and impact force than the multifunctional water gun under the conditions of 0.5 MPa and 0.7 MPa water output from the fire truck. In the actual combustion test, the firefighting device effectively cools down and controls the fire of the burning vehicle. Related Articles | Metrics

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Numerical simulation of flow and transport phenomena for airborne fire extinguishing agents at high altitude Yang Qi1, Wang Xinyu1, Liu Jingjing1, Fan Huailiang2 2024, 43 (7):  1001-1006.  Abstract ( 49 )   In order to investigate the influence of high altitude environment on the dynamics of extinguishing agent flow and transport in aircraft cargo hold fire extinguishing system, this paper adopts Fluent software to numerically model and simulate the dynamics of extinguishing agent flow and transport in the pipeline network of a small Halon 1301 airborne fire extinguishing system device, and obtains the dynamics of transport and release in the pipeline network of Halon 1301 at altitude of 10 000 m and 13 000 m. The transport and release dynamics of Halon 1301 extinguishing agent in the pipe network at high altitude were calculated, and compared and analyzed with three characteristic variables, namely, pressure, phase volume fraction and phase change mass transfer rate during the transport and release process of extinguishing agent at the altitude of sea level. The results show that the transportation and release of extinguishing agents at high altitude follow the “three-phase” process, but the high altitude environment is not favorable to the flow and transportation of extinguishing agents. The results of this study can provide a theoretical basis for optimizing the flow and transport capacity of airborne fire extinguishing systems in high-altitude environments. Related Articles | Metrics

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Study on the flame retardant properties of Chinese fir impregnation and surface coating Yang Zelin, Xu Yanying, Wang Zhi 2024, 43 (7):  1007-1011.  Abstract ( 39 )   Chinese fir is the main tree species for artificial afforestation in southern forest areas of China. It is mostly used in indoor furniture and houses. It has the characteristics of wide use and fast growth. However, Chinese fir has low fire resistance and is prone to fire in high temperature or thermal radiation environment. In order to reduce the risk of fire, this paper proposes a flame retardant process to prepare flame retardant Chinese fir. Chinese fir is immersed in ammonium polyphosphate-borax composite impregnating solution, and melamine is coated on the surface to achieve flame retardant effect. The drug absorption rate, weight gain rate, combustion performance, pyrolysis and ignition characteristics of modified Chinese fir were studied by cone calorimeter, thermogravimetric analyzer and ignition experiment, and the flame retardant mechanism was explored. Compared with logs, flame retardant Chinese fir can effectively reduce the heat release rate and total heat release of Chinese fir during combustion, which plays an important role in delaying its combustion behavior in fire. The total smoke release, CO and CO2 production rate, and the smoke suppression performance was improved. At 800 ℃, the residual carbon rate of flame retardant Chinese fir increased by 160% after pyrolysis, and the thermal stability was improved. The methane torch quickly ignited the logs and burned violently. After 90 s of combustion, the surface lost its overall structure, while the flame retardant Chinese fir did not ignite within 90 s. Related Articles | Metrics

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Analysis of herbaceous fuel load and its influencing factors in typical forest stands of Dalou mountain Liu Xun1,2, Gu Linjing1,2, Zhang Yunlin1,2, Peng Xujian3 2024, 43 (7):  1012-1015.  Abstract ( 31 )   Taking the herbs of six typical forest stands in Dalou mountain as the research object, the differences and correlations in herbaceous load under the same and different forest types were analyzed, and stepwise regression analysis was performed with the forest characteristic factors to obtain a herbaceous load prediction model. The results showed that: the maximum herbaceous load in the broad-leaved mixed forest was 0.759 t/hm2, while the minimum was in the Cunninghamia lanceolata forest, which was only 0.058 t/hm2; The herbaceous load of Pinus massoniana forest is mainly related to the average thickness, while the herbaceous load of broad-leaved mixed forests is mainly influenced by the average coverage and stand density; The goodness of fit of the understory model of Pinus massoniana under the same forest type is 0.885, indicating a good fitting effect. The average thickness, canopy closure, and average ground diameter significantly negatively affect the herbaceous load; The goodness of fit of the model under the broad-leaved mixed forest is 0.973, indicating a good fitting effect. The average thickness significantly positively affects the herbaceous load. This study is of great significance for the study of herbaceous load and scientific forest fire management in Dalou mountain. Related Articles | Metrics

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Kinetics of pyrolysis of Larch humus by multi-peak fitting model decomposition of parallel reactions Chi Hongying, Xin Ying, Huang Tianqi, Zhang Min 2024, 43 (7):  1016-1021.  Abstract ( 30 )   Humus is the main object of forest underground fire shaded combustion, and analyzing its pyrolysis characteristics and calculating kinetic parameters are of great theoretical significance for predicting and extinguishing underground fires. In this study, humus from larch woodland was taken as the object of study, and pyrolysis experiments were carried out under three kinds of heating rates using a thermogravimetric analyzer, and a multi-peak fitting model was proposed for the calculation of kinetic parameters of the experimental data. The model was based on the weight loss rate and acceleration rate curves to obtain the characteristic points, and the fitted peaks were calculated at the characteristic points, and four fitted peaks were obtained for each curve, which were utilized to calculate the kinetic parameters. The results showed that: the activation energy of the fitted peak Ⅰ was low, corresponding to the first peak of the DTG curve; the activation energies of the fitted peaks Ⅱ and Ⅲ were in the middle level, corresponding to the first shoulder and the second peak of the DTG curve; the activation energy of the fitted peak Ⅳ was the highest, corresponding to the last shoulder of the DTG curve. The results of the model's parameter calculations coincide with the kinetic parameter intervals calculated by the Gorbatchev integration method. The residual and goodness-of-fit tests were performed on the model, and the P<0.000 1, root mean square error RMSE<0.005, and goodness-of-fit R2≥0.99 of the fit test (F-test) were obtained. The test results indicated that the multi-peak fitting model can effectively decompose the sub-reactions of humus pyrolysis and calculate the kinetic parameter values, which has certain theoretical significance and practical guidance value. Related Articles | Metrics

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Analysis and research on loss standards for fire classification Jia Hongchen1,2,3, Wang Qiang4, Xu Kaiwen5, Zhang Yan1,2,3, He Yuansheng1,2,3 2024, 43 (7):  1028-1031.  Abstract ( 28 )   In order to analyze and study the reasonable range of loss standards for current fire level classification, based on the development level when the standards were revised in 2007, comparative analysis was conducted by directly using changes in gross domestic product and per capita disposable income of residents, changes in inflation based on CPI, and historical fire data; In addition, the concept of “upper limit of household losses” is introduced, and the severity of losses is measured by calculating the equivalent of “upper limit of household losses” for fire losses, thereby analyzing the adjustment range of current loss standards. By comparing various calculation methods, the boundary values for the classification of fire damage levels were controlled at 29 million to 33 million yuan, 99.58 million to 150 million yuan, and 298 million to 330 million yuan. Therefore, considering the characteristics of fire losses, combined with the analysis and calculation results and the newly revised level standards for maritime traffic accidents, it is recommended to adjust the loss standards for major, major, and particularly major fire accidents to 30 million yuan, 100 million yuan, and 300 million yuan, respectively. Related Articles | Metrics

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Research on fire water supply capacity of municipal pipeline network based on hydraulic model of water supply network Nie Jun1, Pang Yuwen2, Zhao Jiaxiao3 2024, 43 (7):  1032- 1036.  Abstract ( 32 )   In order to improve the level of urban fire safety and the efficiency and quality of fire rescue, based on the hydraulic model of water supply network, this paper studies the fire water supply capacity of municipal pipe network, uses algorithms to analyze and calculate the maximum fire water supply capacity of municipal pipe network that meets the demand of fire water intake under emergency conditions, and obtains the actual water supply capacity of municipal water supply facilities under disaster conditions. Fill the vacuum between the management department of urban fire water supply facilities and the actual fire application unit, solve the problem of "information fault" between various information and "information island" between application systems, give full play to the efficiency of urban fire water supply facilities, and ensure fire safety. Related Articles | Metrics

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Investigation of fire accident caused by high voltage power supply side faults using multiple data Liang Guofu1,2,3, Wang Xin1,2,3, Chang Ying4 2024, 43 (7):  1043- 1046.  Abstract ( 34 )   This article focuses on a large-scale factory fire accident that occurred during typhoon weather. In the early investigation process, the site of the fire was uncertain, the ignition source was unknown, physical evidence could not be extracted, and the cause of the fire could not be determined. By retrieving multi-dimensional electronic data related to the fire site and the cause, such as video data, network data, electricity meter data, and high-voltage recording data, combined with the mechanism and triggering factors of the formation of high-voltage power supply fault traces, comprehensively analyzed and identified the cause of the fire. The investigation can provide reference for the investigation of related types of fire accidents. Related Articles | Metrics

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Research on fire hazards and fire causes investigation technology of hydrogen energy assisted bicycles Meng Jiayi1, Meng Qinggeng2 2024, 43 (7):  1047-1050.  Abstract ( 30 )   Bicycles powered by hydrogen energy have a certain risk of fire to a certain extent. Based on the multiple fire accidents of a certain brand of hydrogen powered bicycles in a certain area of Shanghai, this study investigates the fire hazards and causes of hydrogen powered bicycles, identifies the reasons behind the fire accidents, proposes fire prevention measures, and summarizes the key points of investigation and inquiry for such fire accidents. Related Articles | Metrics