Research on the effect of the component proportion in the new water mist additive on firefighting performance

Water mist technology provides efficient firefighting performance while there is still room for improvement. So varieties of additives have been studied in recent years both at home and abroad. The self-made additives are used to compare the firefighting performance of diesel and heptane fire in open space. By adjusting the concentration of substance in the additives and conducting the experiment under the pressure of 0.3 MPa,0.5 MPa and 0.7 MPa,extinguish time and temperature are measured in the experiment. Through the experiments using different fuels,it can be found when the fuel is heptane that has a lower ignition point and a higher evaporation rate, the water mist additive can still significantly improve the firefighting performance. According to the data based on different concentrations of fluorinated surfactants,we find that fluorinated surfactants are the main substance to improve the performances by changing physical property of water mist. Optimal proportion of the additives for firefighting performance is found by experiment results.

Analysis of Water Mist Suppression with Foam Additive in Wind Generator

The study adopted a 20-foot long container to simulate the situation inside a turbine cabin. Water mist sprays were installed internally and used to perform fire extinguishing tests. Under these different scenarios, several operating factors were adjusted with the results of each adjustment subsequently measured. The operating factors studied included： operating pressures, foam concentrations, cabin opening issues, and obstacles. Each of the factors was compared with the others so as to find out which combinations would be most suitable for a water mist spray system installed inside a wind turbine cabin. The presence of obstructions hinders the direct impact of the mist spray on the fire source and in average an additional 2 to 3 minutes is required to put out the fire. This study found that the effect of the foam-water ratio is linear. Regardless of the scenario, the optimum mixture ratio is 3%. The line graph shows that the most unsuitable aqueous film-forming mixture ratio is 6%. This experiment found that the main fire extinguishing mechanism of water mist spray is the cooling of a large area via water droplets. This system is very effective in bringing down the temperature. The addition of foam in water mist spray, however, impaired the effectiveness of the cooling effect although the fire control mechanism via emulsification markedly reduced the time required to put out the fire. The increase in foam magnification will considerably enhance the fire extinguishing efficiency.

The principle analysis of methane explosion suppressed by water column curtain in coal mining

The principles of fine water mist explosion-extinguishing system was introduced. The defects of current systems were analyzed. The concept of a new water column cur-tain and the explosion-extinguishing mechanism were given. Using water column curtain to suppress methane explosion in experiment pipes was conducted. The photos were written with schlieren photograph system. The results of experiment show that the effect is perfect.

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.

气凝胶灭火剂抑制锂离子储能电池热失控特性研究

通过对比试验探究了气凝胶灭火剂对锂离子储能电池热失控的抑制效果。研究满荷电状态下的100 Ah磷酸铁锂储能电池热失控演变过程特征参数,识别出3个灾害演变特征拐点作为灭火剂施加的指导节点。在相同节点分别施加灭火参数一致的气凝胶灭火剂与细水雾开展灭火对比测试。结果表明:触发明火前施加灭火剂均可有效阻断电池内部放热副反应,两者表现出相似的冷却效能;电池起火后,气凝胶灭火剂展现出更为出色的明火抑制效果,其接触电池表面形成的致密泡沫可有效阻隔氧气,实现快速灭火;对于已经触发热失控的情形,气凝胶灭火剂凭借预热覆盖效果,显著缩短电池射流火持续时间,可大幅降低电池火灾危害。

城市地下综合管廊电缆火灾低压细水雾灭火效能研究

为了研究城市地下综合管廊电缆火灾低压细水雾灭火的有效性、明确影响低压细水雾灭火效能的关键因素,搭建了缩尺寸综合管廊低压细水雾灭火试验平台并开展了灭火试验。试验结果表明,低压细水雾能够快速有效地扑灭综合管廊电缆火灾,灭火时间最快为7 s,在启动灭火系统后50 s即可将管廊内部最高温度从650℃降至40℃。压力与喷头流量系数的改变对低压细水雾灭火效能影响较大,灭火时间分别最多缩短75.0%和66.7%,平均降温速率最高为8.2℃/s和7.43℃/s;喷头间距的改变对灭火效能影响相对较小,灭火时间最多缩短47.3%,平均降温速率最高为6.1℃/s。

含添加剂水雾抑灭单基药火焰的小尺度实验研究

为探究含不同性质添加剂的水雾对单基火药燃烧抑灭性能的影响,在自主搭建的火药燃烧及灭火平台上开展纯水雾与含Na_(2)SO_(3)、FeCl_(2)、K_(2)CO_(3)、KHCO_(3)添加剂的水雾对单基火药燃烧抑灭性能的对比实验,研究灭火过程中温度、辐射热流、火焰形态等的变化。结果表明:含还原性(Na_(2)SO_(3)、FeCl_(2))和非还原性(K_(2)CO_(3)、KHCO_(3))添加剂的水雾抑灭性能明显优于纯水雾,灭火时间更短。含非还原性添加剂的水雾在低浓度下抑灭效果较差,当添加质量分数提升至3%以上时,抑灭效果显著提升;含还原性添加剂水雾对单基药的抑灭性能在各添加剂浓度下均优于含非还原性添加剂的水雾,且随着添加剂浓度的增大,抑灭性能表现出饱和性。

文物建筑内移动式高压细水雾灭火装置设计参数研究

为了研究移动式高压细水雾灭火装置在文物建筑内的设计参数,搭建了6A木垛火试验台,研究在不同喷射距离和模式下,该装置应对大规模火灾时适合的喷射流量与距离,并采用FDS,以北京某古建筑为模型进行模拟,从喷射强度、喷射距离、喷射时机、雾化粒径等方面验证并补充移动式高压细水雾灭火装置的设计参数。结果显示,喷射强度可设定为4.4~6.6 L/(min.m^(2));喷射距离可设定为5 m,尽可能采用近距离喷射策略;灭火时机应尽早,至少在起火后300 s内;雾化粒径的选择需根据具体情况权衡考虑。

超声波细水雾灭火技术试验研究

利用超声波技术产生的细水雾可作为一种灭火剂,通过冷却、窒息等作用实施灭火。搭建试验平台,分析超声波雾化装置产生细水雾的特性,并设计灭火试验,研究局部应用和全淹没两种形式的灭火有效性和影响因素。结果表明:利用超声波雾化技术产生细水雾并确保足够雾化量和适宜的喷射方向,实施局部应用灭火是可行的;采用全淹没灭火时,灭火效果取决于场所通风情况和空间大小,在相对封闭空间内灭火效果较好。

气体灭火系统和细水雾灭火系统在医院建筑中的应用及对比分析

介绍了气体灭火系统和细水雾灭火系统的灭火原理;以重庆某大型综合医院为例,对医疗设备、电气机房等进行消防灭火设计和对比分析,研究气体灭火系统和细水雾灭火系统的适用性及经济性;通过对比分析,对两种系统的选用提出相关建议。

电缆竖井细水雾灭火系统数值模拟研究

利用数值模拟技术研究了电缆竖井不同高度和通风条件对细水雾灭火效果的影响,按典型高低压电缆井断面情况,基于火灾动力学软件,模拟了细水雾灭火系统在电缆竖井中不同通风条件下的控火和灭火效果,同时对细水雾灭火系统在电缆竖井中的形式、喷头布置方式等进行说明,得到在限定条件下的火灾规律性结果和相应的应用边界条件等结论,为电缆竖井防火实验研究和工程设计提供参考。

某客滚船低压水雾灭火系统设计

本文以某客滚船为例,介绍低压水雾灭火系统的组成及保护分类、系统水量估算方法、系统满足客船安全返港要求的布置特点以及设计过程碰到的有关问题。

Experimental study on the interaction of fine water mist with solid pool fires

This paper describes experimental study of the interaction of fine water mists with solid pool fires. Fine water mist was generated by a single pressure nozzle and solid pool fires were produced from solid red pine or polymethyl methacrylate(PMMA). The LDV/APV system was em-ployed to determine the water mist characteristics. The water mist droplet sizes and velocities from the nozzle were measured under varying conditions and at different locations. The effects of solid type, water flow rate, and nozzle distance from the sample surface on extinguishments time were examined. At a given water flow rate, the extinguishment time is much longer for PMMA fires than for solid pine fires. The extinguishment time was found to decrease with increasing water flow rate. At very low water flow, the extinguishment time decreases when the nozzle is positioned further from the sample surface. On the contrary, at high water flow, the extinguishment time appears to be independent of the distance between the nozzle and the sample surface. The experimental re-sults show that flame extinguishments is due primarily to fuel surface cooling and wetting.

Fire Extinct Experiments with Water Mist by Adding Additives

The effects of fire extinguishment with water mist by adding different additives were studied.Tens of chemical substances (including alkali metal salt,dilution agent and surface active agent) were selected as additives due to their different extinct mechanisms.At first the performance of fire extinguishment with single additive was studied,then the effects of the same kinds of chemical substances under the same mass fraction were compared to study their influences on the fire extinguishment factors,including extinct time,fire temperature and oxygen concentration from which the fire extinct mechanism with additives could be concluded.Based on this the experiments were conducted to study the cooperate effect of the complexity of different additives.It indicated the relations between different firefighting mechanisms and different additives were competitive.From a large number of experiments the extinct mechanism with water mist by adding additives was concluded and an optimal compounding additive was selected.

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.

船舶典型舱室内细水雾灭火降温性能仿真研究

细水雾灭火系统在船舶消防领域得到广泛应用,但是针对船舶舱室细水雾灭火性能的研究相对有限。为探究细水雾对船舶火灾灭火的有效性,采用FDS软件,针对细水雾在两类典型的船舶舱室(大空间的储存舱室和小空间的起居舱室)发生火灾后的灭火效果进行了仿真模拟研究。分析了粒径、雾化角度和流量系数对灭火降温性能的影响。仿真结果表明,大空间的储存舱室内细水雾灭火性能不佳,不能进行灭火降温;小空间的起居舱室内细水雾灭火降温性能相对良好。揭示了细水雾在起居舱室内的灭火性能随粒径减小而增强、随雾化角度减小而增强、随流量系数增大而增强的演化特性。

穿斗式民居建筑高压细水雾系统控火效果研究

高压细水雾良好的冷却降温效果,对建筑初期火灾具有较好的抑制作用,可有效解决木结构建筑防火间距不足的问题,阻止建筑间火灾蔓延的发展。为探究高压细水雾雾化锥角、水压强度、喷雾速度及粒径大小等因素对木结构建筑火灾控火效果的影响,选取典型穿斗式民居建筑为研究对象,采用FDS建立火灾模型,分析上述各因素对细水雾抑制木结构建筑火灾效果的影响。结果表明:上述影响因素均对高压细水雾的控火效果具有较大影响,雾化锥角为120°、喷雾压力为10.00MPa、喷雾速度为10 m/s、粒径大小为300μm时的灭火效果最佳,可以产生最高的渗透能力,7.3 s即可完成灭火。

储能电站磷酸铁锂电池模组灭火参数的仿真优化

为研究储能场景下磷酸铁锂电池组热失控火灾的最佳灭火方式,通过火灾动力学模拟软件建立储能电池模组等尺寸模型;对模型开展不同热失控位置、细水雾流量、雾滴直径和细水雾喷头布置位置的仿真实验.仿真结果表明:细水雾流量和雾滴直径对灭火效果有很大影响,适当增大细水雾流量、减小雾滴直径可以明显提升灭火效果;综合灭火系统设计安全性及制造成本,确定最佳灭火参数组合为细水雾流量2.0 L·min^(-1)、雾滴直径200μm、细水雾喷头布置位置为电池箱顶部中央.

高压细水雾灭火系统抑制古建筑轰燃的试验研究

为探明高压细水雾对古建筑火灾轰燃的抑制效果,通过Pyrosim软件模拟与搭建试验平台的方式进行试验,测定了火灾联动报警下细水雾的自启动时间,以及不同喷雾强度下古建筑火灾烟气层温度、火场热释放速率,并结合综合轰燃预测法分析了开启细水雾时古建筑内轰燃发生状况。结果表明,当火灾发生后103 s时开启细水雾,喷雾强度1.3 L/(min.m2)的高压细水雾能抑制古建筑火灾轰燃,喷雾强度2.0 L/(min.m2)的高压细水雾能熄灭古建筑火灾;试验证明了高压细水雾能够有效地抑制古建筑火灾轰燃,为高压细水雾灭火系统应用于古建筑消防设计提供参考。

抽水蓄能电站油浸式主变压器灭火系统分析对比研究

通过对比水喷雾灭火、细水喷雾灭火、气体灭火、泡沫水喷雾灭火以及排油注氮灭火方式在抽水蓄能电站油浸式主变压器灭火时的使用规范以及异同点,同时对比分析不同灭火方式的优缺点,从消防系统响应时间、储存运输的安全性、事故后清理效率、使用成本以及应对主变复燃情况下的二次处理等多维度进行分析,结合抽水蓄能电站主变布置的实际情况,给出抽水蓄能电站优选的消防灭火系统方案。