Understanding the combustion behavior of electric bicycle batteries and unveiling its relationship with fire extinguishing

In this study,a detailed analysis of the combustion behaviors of the lithium iron phosphate(LFP)and lithium manganese oxide(LMO)batteries used in electric bicycles was conducted.This research included quantitative measurements of the combustion duration,flame height,combustion temperature,heat release rate,and total heat release.The results indicated that LMO batteries exhibited higher combustion temperatures of 600–700°C,flame heights of 70–75 cm,a significantly higher heat release rate of40.1 k W(12 Ah),and a total heat release of 1.04 MJ(12 Ah)compared to LFP batteries with the same capacity.Based on these experimental results,a normalized total heat release(NORTHR)parameter was proposed,demonstrating good universality for batteries with different capacities.Utilizing this parameter,quantitative calculations and optimization of the extinguishing agent dosage were conducted for fires involving these two types of batteries,and the method was validated by extinguishing fires for these two types of battery packs with water-based extinguishing fluids.

Enhancing Fire Safety in Commercial Vehicles: Assessing the Efficacy and Advantages of Exploding Fire Extinguishing Balls

Fire incidents in commercial vehicles pose significant risks to passengers, drivers, and cargo. Traditional fire extinguishing systems, while effective, may have limitations in terms of response time, coverage, and human intervention [1]. This study investigates the efficacy of a novel fire suppression technology—the Exploding Fire Extinguishing Ball (EFEB) —as an alternative and complementary fire safety solution for commercial vehicles. The research employs a multidisciplinary approach, encompassing engineering, materials science, fire safety, and human factors analysis. A systematic literature review establishes a comprehensive understanding of existing fire suppression technologies, including EFEBs. Subsequently, this study analyzes the unique features of EFEBs, such as automatic activation, as well as manual activation upon exposure to fire, and their potential to provide rapid, localized, and autonomous fire suppression. The study presents original experimental investigations to assess the performance and effectiveness of EFEBs in various fire scenarios representative of commercial vehicles. Experiments include controlled fires in confined spaces and dynamic simulations to emulate real-world fire incidents. Data on activation times, extinguishing capability, and coverage area are collected and analyzed to compare the efficacy of EFEBs with traditional fire extinguishing methods. Furthermore, this research shows the practical aspects of implementing EFEBs in commercial vehicles. A feasibility study examines the integration challenges, cost-benefit analysis, and potential regulatory implications. The study also addresses the impact of EFEBs on vehicle weight, stability, and overall safety. Human factors and user acceptance are crucial elements in adopting new safety technologies. Therefore, this research utilizes an experimental design to assess the performance and effectiveness of EFEBs in various fire scenarios representative of commercial vehicles. This dissertation presents original controlled experiments to emulate real-world fire incidents, including controlled fires in confined spaces and dynamic simulations. The experimental approach ensures rigorous evaluation and objective insights into EFEBs’ potential as an autonomous fire suppression system for commercial vehicles. This includes the perspectives of drivers, passengers, fleet operators, insurance agencies, and regulatory bodies. Factors influencing trust, perceived safety, and willingness to adopt EFEBs are analyzed to provide insights into the successful integration of this technology. The findings of this research will contribute to the knowledge of fire safety technology and expand the understanding of the applicability of EFEBs in commercial vehicles.

Research Progress of Polymer Fire Extinguishing Gel and Its Application in Forest Fire Prevention

The paper summarizes the structure and water-absorbing mechanism,classification,and preparation method of polymer fire extinguishing gel,and prospects for its application in aerial firefighting,forest ground fire extinguishing,opening of firebreaks,and mitigating human casualties in forest fire extinguishing.

Research on the Control Cover against Solenopsis invicta and Rapid Extinguishment of Its Epidemic

Based on the biological characteristics of Solenopsis invicta and the structural characteristics of its ant nest,a fast and efficient closed treatment device was developed.Compared with the simple chemical treatment commonly used at present,the developed treatment device(the ant nest control cover)is a fast and efficient method to exterminate S.invicta in 7 d,featured by short course,quick results and good effect.

Characteristics of seal shell body's rubber ring with bionic dimpled surfaces of aerodynamic extinguishing cannon

To solve the problem of sealing between the barrel and the rubber ring of shell body during an launching process of aerodynamic extinguishing cannon, a rubber sealing model with bionic dimpled characteristics was established based on the theory of bionic dimpled drag reduction and the principle of rubber sealing. In condition that the bionic dimpled characteristic diameters were 1, 2, 3, 4, and 5 mm, respectively, by numerical simulation, the influence of the installing compression of the rubber sealing ring on its surface stress and deformation was analyzed, and sealing performance of the rubber ring with different diameters of bionic dimpled was studied. The results show that the deformation of rubber ring appears prominent nonlinear characteristics when compression is increased from 1.5 mm to 2.5 ram. When the compression is 2.5 mm, the equivalent compression stress on the sealing areas of both sides of the rubber seal is greater than the working pressure of aerodynamic extinguishing cannon, which could meet the sealing requirement and would not cause leakage. So the rubber sealing ring with bionic dimpled surface possesses a good sealing characteristic and has no negative effect on the sealing of shell body; When the compression is 2.5 mm, the larger equivalent stress on the edge of sealing ring and the more even stress distribution in the high pressure area are generated due to the smaller compressive stress on the bionic dimple areas, which lays a foundation for the drag reduction characteristics of the shell body＇s rubber ring with bionic dimpled surface.

Theory and Practice of Controlling and Extinguishing Pine Wilt Disease

[Objective] This study was aimed to review the controlling experience of pine wilt disease in the past 25 years, explore the theories and methods of controlling pine wilt disease, and improve the scientific level of controlling techniques and the protection capacity of healthy pine trees. [Method] Eleven items of effects were used to refine the theory of clearing dead pine trees affected by pine wilt disease, namely, ＂1 priority＂, ＂2 objections＂, ＂3 principles＂, ＂4 measures＂, and ＂5 manage- ments＂. On the basis of comprehensive control and complete removal of the infect- ed pine trees, a variety of comprehensive and efficient controlling methods were developed to carry out targeted chemical ecology trapping, bionic pesticide killing and releasing natural enemies of Sclerodermus guani, Dastarcus helophoroides. High ef- ficient emamectin benzoate immune injection was developed to inject the healthy pine trees for prevention, so as to extinguish the pine wilt disease. [Result] The pine wilt disease dropped from the peak of 3.5 million dead trees with an infecting area of 28 273 hectares in 1999 to 0.068 million with an area of 4 333 hectares in 2012 gradually, reducing by 98.06% in number and 84.84% in area, respectively. On the basis of removal, Dastarcus helophoroides was also released, which could make the number of dead pines decrease more significantly than the control, and af- ter releasing for 5 consecutive years, the dead pine trees dropped to 0.511 plant/hm2 in 2012, with a mortality rate of 0.022 7%, which achieved the control effect, reaching extremely significant level. ＂Forest land removal＋infected trees isolation＋natural enemy release＂ could extinguish the pine wilt disease. The test of isolating 24 heaps of infected pine trees showed that there were 9 heaps of pine trees extinguished the pine wilt disease, which controlled the occurrence of pine wilt disease for 100%, accounting for 37.5% of the total, in which the number of those isolated using iron netting and nylon net were 4 for each, accounting for 88.9%, and there was one heap using polypropylene net, accounting for 11.1%. The invention of em- amectin benzoate immune injection laid the foundation for extinguishing pine wilt disease. The follow checking of the effects of emamectin benzoate immune injection on pine wilt disease found that the number of dead trees caused by pine wilt dis- ease decreased significantly after injecting, and became very small in October of the next year, and the disease was completely extinguished in the third year. [Conclusionl Pine wilt disease could be controlled and extinguished with positive control by using ＂comprehensive cleaning＋industrialized removal＂, ＂comprehensive cleaning＋ natural enemy release＂, ＂comprehensive cleaning＋infected trees isolation＋natural ene- my release＂ and ＂comprehensive cleaning＋emamectin benzoate immune＂.

Hysteresis characteristics of the initiating and extinguishing boundaries in a nanosecond pulsed DBD

The dielectric barrier discharge(DBD)is presently used in many fields,in eluding plasma medicine,surface modification,and ozone synthesis;the influe nee of airflow on the DBD is a widely investigated topic.In this work,a hysteresis characteristic on the initiating and extinguishing boundaries is observed in a nanosecond pulsed DBD,which is sensitive to the variation in the airflow velocities and pulse repetition frequencies(PRFs).It is found that,at a certain airflow velocity,the initiating PRF is higher than the extinguishing PRF.This differenee between the initiating PRF and the extinguishing PRF leads to a hysteresis phenomenon on the initiating and extinguishing boun daries.When the airflow velocity is in creased,both the initiating and extinguishing PRFs are increased and the differenee between the initiating PRF and the extinguishing PRF also increased.The hysteresis width between the initiating and extinguishing boundaries is enhanced.To explain these results,the physical processes involved with the seed particles and the mechanisms of forming discharge channels are discussed.

“Relay-mode”promoting permeation of water-based fire extinguishing agent in granular materials porous media stacks

Water-based fire extinguishing agent is the main means to deal with smoldering fires.However,due to the hydrophobic properties of the particle surface,the porous medium channel provide resistance and slow down the extinguishing agent flow during the downward permeation process.To promote the liquid permeation process in such porous media,this work studied liquid imbibition process and analyzed the oscillating and attenuating process of liquid level in capillary channel by theoretical,experimental,and numerical methods.An empirical mathematical equation was proposed to describe the oscillating process,and the effects of the capillary diameter and contact angle parameters on the transportation process were analyzed.Based on this,the“relay-mode”was proposed to promote the liquid transportation forward.Finally,the transient simulation results of liquid permeation in coal stacks showed when the liquid flowed through the channel with changed diameter from large to small ones,the transportation distance was several times longer than that through the unidiameter ones.The trend of liquid“relay-mode”in capillaries can be used to promote the permeation in granular materials porous media stacks.The relevant results also provide new thoughts to develop the water-based fire extinguishing agents and then improve the firefighting efficiency of deep-seated fire in porous media stacks.

Nonlinearity of initiating and extinguishing boundaries of DBDs with airflows

Various applications of volume dielectric barrier discharges(DBDs)with airflows have attracted significant attention such as in the fields of plasma medicine,surface modification,ozone synthesis,etc.In this work,the nonlinearity characteristics of DBDs in initiating and extinguishing boundaries with airflows are experimentally investigated.It is found that the difference between initiating pulse repetition frequencies(PRFs)and extinguishing PRFs is affected by the addition of airflows.A hysteresis region is produced between these two PRFs.A topological rule of Thom's classification theorem is proposed to investigate the hysteresis phenomenon of discharges with airflows.It is concluded that the discharge state is dependent on the operation route.The discharge state would transit from initiating to extinguishing,or in the opposite direction,while passing along a specific operation route.Based on the topological method,two nonlinear laws of discharge structure transition under the typical operation routes are predicted and verified in the discharge experiments.

Protective effect of compressing arc extinguishing lightning protection device on superimposed lightning strikes

Traditional lightning protection measures can not solve the problem of superimposed lightning strikes.This paper presents a compressing arc extinguishing lightning protection device,which can solve the problem of superimposed lightning strikes.This device can extinguish the power frequency continuous current arc quickly in 1-2 ms.It is far less than the response time of relay protection,which can avoid lightning trips and improve the reliability of power supply.The computer simulation and engineering practice show that the compressing arc extinguishing device has good protection effect on superimposed lightning strikes.

Study on Test Methods for Flow Ability of Superfine Powder Extinguishing Agent

According to the physical and chemical characteristics of superfine powder extinguishing agent,three test methods are selected to measure the flow ability.By studying and comparing various test methods,apparatus and conditions,the optimum method and conditions to test flow property of superfine powder extinguishing agent are confirmed.

FIRE-EXTINGUISHING MECHANISM AND ENERGY PROCEDURE BY HIGH VELOCITY AIRFLOW

Based on the testing restult of character of forest fire, with the aid mold of flameextinguishing and mathematical method, the combustion of the forest fuels and the energy transtfer under the convention condition were studied and the mechanism and interrelated elements of flameextinguishing with high velocity airflow were given. The energy formulae is given:Nz =Ka0 L0 (15)GH/102η through combustion calculation and test revision This formula was checked through simulated testing for extinguishing low, medial and high intensity fires with high velocity airflow.

基于杯式燃烧器测试系统的灭火性能评价研究进展

杯式燃烧器试验是消防领域用于测定气体灭火剂最小灭火浓度的经典方法。自哈龙灭火剂被淘汰以来,哈龙替代物经历了不同相态的发展,促使杯式燃烧器测试系统进行相应的改进,同时基于杯式燃烧器测试系统的灭火性能评价研究也在不断拓展。综述了国内外杯式燃烧器测试系统的使用和改进研究,重点介绍了适用于气相、液相、固相和复合相灭火剂的杯式燃烧器测试系统和测试方法,分别对气相、液相、含添加剂细水雾、干粉、复合灭火剂的灭火效率进行了总结和分析,综述了各相态灭火剂灭火性能评价研究。未来,杯式燃烧器测试系统仍将不断被改善,在灭火剂筛选和灭火性能评价等方面将发挥更重要的作用。

泡沫灭火综合教学实验平台的设计与实践

根据消防工程专业课程实践教学中的灭火实验需求,设计和搭建了泡沫灭火综合教学实验平台,该实验平台由发泡实验平台、析液实验平台、蔓延实验平台、灭火实验平台和抗烧实验平台构成,能够实现泡沫灭火剂的稳定性、蔓延性能、灭火效能和抗烧性能的测试,满足泡沫灭火实验教学要求。通过实验操作与结果分析将理论与实践紧密联系,有助于巩固学生理论知识和增强学生学习兴趣,为培养具有工程实践和科研创新能力的高素质和高质量消防人才发挥积极作用。

自走引流式森林风力灭火机设计与试验

为提高森林火灾初期灭火的效率,设计一种应用于森林火灾初期快速灭火的新型自走引流式森林风力灭火机。首先对灭火机的整体结构、工作原理进行阐述,对风筒等关键部件进行设计计算。其次利用UG对灭火机的结构进行设计,用ANSYS静力学、模态分析模块对整机机架进行仿真分析,验证整机机架设计的合理性与工作特性。最后对样机进行试制,与我国常见的6MF-32便携式灭火机作对比试验,自走引流式森林风力灭火机距可燃物5 m,手持式6MF-32灭火机距可燃物2.5 m。试验结果表明,在7次对比试验中,当可燃物量大于2.5 kg时,6MF-32便携式灭火机出现灭火后复燃现象;当可燃物的质量达到3.5 kg时,风力灭火机会出现灭火后复燃现象。试验中,自走引流式森林风力灭火机的灭火时间比6MF-32便携式灭火机短,因此可以看出自走引流式森林风力灭火机在灭火距离、效率上的优越性。

基于发电机定子接地燃弧电阻变化特征的主动降压熄弧机理与抑制方法

定子接地燃弧故障是制约大型发电机安全可靠运行的技术瓶颈。为解决定子绕组接地电弧引发的绝缘击穿与铁心损伤问题,该文提出基于发电机定子接地燃弧电阻变化特征的柔性接地主动降压熄弧方法。该文建立了定子接地燃弧电阻与弧道电压的解析关系,揭示了定子接地故障点电压降低过程中,接地燃弧电阻增大的变化规律;明确了将接地故障点电压抑制在电弧重燃电压以下时,可实现定子绕组击穿间隙回归正常绝缘状态的抑制方法。根据大型发电机定子柔性接地方式降压熄弧策略,在接地故障燃弧阶段,中性点电压源输出故障点工频与3次谐波反向电势,主动降低故障点电压,将故障点电压降低至燃弧电压以下,使定子接地电弧熄灭。利用注入信号感知定子接地燃弧状态,实时监测定子阻尼率矢量角变化趋势,判定降压消弧过程中接地燃弧故障是否消除。所提方法无需将故障点电压降低至零,可有效降低非故障相电压抬升,降低定子非故障相绕组槽内击穿风险。在PSCAD/EMTDC仿真环境模拟定子接地故障燃弧工况,对所提方法进行试验验证。试验结果表明,基于定子接地燃弧电阻变化特征的柔性接地消弧方法可主动降低定子接地故障点电压,助增故障点间隙绝缘电阻回归,抑制接地电弧重燃,降低定子非故障相绝缘击穿风险,实现定子接地燃弧故障的可靠消弧。

基于可控串联电抗的新能源送出线路故障性质识别方法

针对不带并联电抗器的新能源送出线,能否正确区分故障性质是确保新能源系统安全可靠运行的重中之重。为降低新能源送出线故障对电力设备和系统的冲击,提高重合闸成功率,减少新能源发电系统脱网的发生,提出基于可控串联电抗限流信息的新能源送出线路故障性质识别方法。在送出线路上设计串联可控限流电抗器,在线路故障相跳闸时基于等值阻抗的预判投入可控电抗,在串联电抗限流特性下分析瞬时性故障和永久性故障时的线路电流差异,建立电流突变量比较判据,并能够确定故障电弧熄灭时刻,进而构建新能源场站送出线路基于故障性质识别的自适应重合闸策略。仿真结果表明,所提方法能快速、可靠地识别结果,应用在新能源场站送出线路工程上能有效提高线路的重合率。

定量核磁共振波谱法快速测定灭火剂材料中全氟辛烷磺酰基化合物

泡沫灭火剂中全氟辛烷磺酰基化合物(PFOS)的使用受到严格管控.针对灭火剂中PFOS快速测定的需求,建立了基于19F的定量核磁共振波谱(qNMR)检测方法.方法以全氟丁基磺酸钾为标准物质,通过计算全氟丁基磺酸钾的-CF3在化学位移δ-78.94处19F特征峰和PFOS的-CF2在化学位移δ-117.12处19F特征峰的积分面积比值,进而实现PFOS定量分析.经测试,全氟丁基磺酸钾百分含量与定量峰面积线性相关系数为0.9955,检出限为0.024%,定量限为0.080%.8种灭火剂产品的定性测定结果与实际标注情况相吻合,其中4种泡沫灭火剂产品中PFOS含量在0.106%~1.339%之间.研究结果表明,方法受基质干扰小、检测速度快、灵敏度高,可为泡沫灭火剂中PFOS的管控提供可靠的检测方法与数据支撑.

南京定淮门长江隧道新增自动灭火系统设计探讨

南京定淮门长江隧道为国内已通车的最长水下双管双层盾构隧道,鉴于定淮门长江隧道内现状无自动灭火系统,从隧道运营安全及防灾救援的角度考虑,拟在隧道内增设自动灭火系统。通过对国内水下隧道自动灭火系统设计的研究现状进行分析后,对隧道新增泡沫/水喷雾系统设计的重难点进行了分析,详细介绍了其针对性的设计解决方案及系统中的重要设备设施,包括:隧道专用泡沫喷头的选型、隧道泡沫/水喷雾系统分区设计、新增消防泵房及消防水池选址、消防管道设置、水力计算、系统控制要求及运行控制系统的设计等,总结了设计中的创新点并进行了展望。

疏水改性纳米氧化镁对短氟碳链泡沫性能影响

为了解决短氟碳链泡沫稳定性差的缺点,采用硬脂酸对氧化镁纳米颗粒(MNPs)疏水改性得到不同水接触角的G-MNPs,研究疏水改性MNPs对短氟碳链泡沫性能和灭火性能的影响。采用硬脂酸对MNPs分别改性60min、90min、120min和150min,测试了G-MNPs表面形态、粒径分布、疏水性、热稳定性以及溶液分散度,研究了疏水改性对泡沫稳定性、发泡能力、泡沫粗化、灭火性能和抗烧性能等的影响。结果表明,硬脂酸疏水改性时间为120min时,改性MNPs水接触角最大,达到138.4°;G-MNPs表面形貌粗糙度增加,颗粒粒径增大,高温下热稳定性良好;疏水改性对泡沫溶液表面张力和黏度几乎没有影响;疏水角为90.0°时,G-MNPs泡沫溶液发泡性能、稳定性能、灭火性能、抗烧性能达到最佳。