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.

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.

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.

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.

Diagnosis and Extinguishment of Camel Rabies

The diagnosis process and extinguishment measures of a case of camel rabies was introduced from the aspects of medical history, clinical examination, emergency and extinguishment measures, in order to provide some references for clinical veterinarians.

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.

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.

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.

Study on fire extinguishing performance of ultrafine water mist in a cup burner

Two simplified models for predicting minimum extinguishing concentration(MEC) of ultrafine water mist(UFM)(<10 m) were developed based on limiting oxygen concentration(LOC) and combustion limit temperature(CLT),respectively.Experiment was conducted using a modified cup burner which can reduce the surface adsorption of UFM.Two typical liquid fuels,n-heptane and ethanol,were used in the experiment.Tests using the same scenario were repeated 20 times or 10 times according to the variance of extinguishing time.The average and the standard deviations of extinguishing time were used to evaluate the fire extinguishing performance of UFM.Experimental results agree well with the model based on LOC,and disagree with the model based on CLT.The disagreements were explained by analyzing flow behavior of UFM.It was concluded that the primary mechanism of fire extinguishment with UFM was oxygen dilution.

Calculation of fire extinguishment time with water mist in an enclosed room

The fire extinguishment time is a major factor to evaluate the efficiency of fire extinguishment with water mist. In this paper the fire extinguishment time with water mist in an enclosed room is calculated. Before adding water mist, the chemical kinetics plays the role in combustion, where a dimensionless math model is established by us-ing the Semenov theory. After adding water mist, the diffusion plays the role instead. Then another math model containing water mist and dominated by oxygen concentration is established. The fire temperature is integrated from Tm to extinguishment temperature TB and the extinguishment time can be obtained. The calculated values are compared with the experimental data under different conditions. The results show that this model can predict the fire extinguishment time accurately. Besides, this model also can be used to determine the critical water mist flux and evaluate which fire extinguishment mechanisms dominate the extinguishment.

Modification of ADP extinguishing powder by siliconization in spray drying

Superfine spherical fire-extinguishing powder, ammonium dihydrogen phosphate （ADP, NH4 H2 PO4）, was prepared by spray drying and modified in situ with methyl hydrogen silicone oil （MHSO） emulsion and the fluorinated surfactant FK-510. The influences of the MHSO mass ratio on the hydrophobicity, sur- face composition, surface morphology, dispersion and particle-size distribution of the NH4H2PO4 were studied, and the influence of the drying air temperature on the decomposition of the NH4H2PO4 was also researched. The results indicate that the MHSO and FK-510 congregate on the particle surfaces and then form a hydrophobic shell. This shell improves the particle hydrophobicity and leads to a fine dispersion of the particles. During the process of preparing the precursor solution, 3 wt% （based on the weight of NH4H2 PO4 ） was chosen as the optimum value of the MHSO mass ratio. During the spray drying, a low abso- lute humidity of the air should be maintained, and it is very important to keep the exit-air temperature below 100℃ to avoid decomposition.

Experimental study on fire extinguishing with a newly prepared multi-component compressed air foam

A multi-component compressed air foam system (MCAFS) was developed with newly prepared multi-component foaming agents. Extinguishing of wood crib and oil pool fires was performed under different conditions, such as foam concentration, mixing chamber forepart structure and working pressure. It was found that the foam concentration had sufficient effects on fire extinguishing efficiency, and an optimized concentration value exists. For instance, for diesel oil pool fires, this value is about 2.2% while it is about 4.0% for wood crib fires. The results also show that the system with a coaxial mixing chamber has greater efficiency than a T-shape. The effects of working pressure on fire extin- guishing are evident in experiments, i.e., the higher the working pressure is, the more readily the fire is extinguished.

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。

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。