障碍物遮挡条件下细水雾与油池火相互作用的实验研究

障碍物影响下细水雾灭火有效性的研究具有重要的意义。研究了障碍物与火焰的相对位置、细水雾工作压力、喷头距离火焰垂直距离及水平距离等因素对灭火有效性的影响,以及细水雾作用下火灾烟气中一氧化碳、二氧化碳及氧气浓度的变化规律等。结果表明:高压细水雾可以有效扑救部分有障碍物遮挡的油池火,同时喷头距离火焰的水平距离和垂直距离也显著影响着细水雾的灭火速度;高压细水雾在灭火过程中火场的氧气浓度明显升高,二氧化碳和一氧化碳浓度明显降低;细水雾工作压力较低时,一氧化碳浓度反而有所增加。     

标准受限空间内细水雾熄灭煤油火的实验和数值模拟

在3.0m×3.0m×2.8m标准受限空间内,采用煤油模拟池火,火灾功率设定为195kW,进行了一系列细水雾灭火试验。对灭火时间做了详细记录,并实验研究了灭火时间的重现性及其相关因素。采用M-9000燃烧分析仪对细水雾施加前后火灾烟气(如氧气、二氧化碳、一氧化碳、一氧化氮、二氧化氮、二氧化硫)的浓度进行了在线测量。其结果表明:细水雾灭火系统熄灭煤油火的时间均在20s以内,灭火时间重现性保持在91.9%以内;施加细水雾后,氧气浓度降低,一氧化碳浓度升高,燃烧更加不完全。采用FDS模拟了细水雾熄灭煤油火,预测的温度场和灭火时间与实验结果吻合较好。     

受限空间细水雾熄灭油池火机理探讨

细水雾熄灭油池火机理一般为气体冷却、表面冷却、稀释氧气及衰减辐射,但在一些受限空间内细水雾熄灭油池火的机理是其中一种或者几种的组合。在受限空间内,细水雾扑灭火灾的影响因素还包括开口面积、开口处空间内和空间外的温度差及可燃物的燃烧强度。通过对受限空间细水雾灭火机理的探讨研究,分析了在特定条件下细水雾灭火的影响因素,推出了在受限空间内细水雾灭火时间的大致规律。     

细水雾特性参数对锂离子电池组灭火效果的影响

为了研究不同特性参数细水雾抑制锂电池组火灾的效果,利用计算流体动力学模型和火灾动力学模拟程序对不同特性参数细水雾灭火效果进行了分析.采用锥形量热仪在50 kW/m2辐射热条件下和100％荷电状态下对锂离子电池进行燃烧试验,获取其热释放速率曲线,热释放速率峰值为9.23 kW.在试验获得参数的基础上以6个18650型锂电池建立火灾模型,利用火灾场模拟软件FDS对不同雾滴直径、雾动量和喷雾强度的细水雾的灭火过程进行数值模拟.定量分析熄灭锂离子电池火的细水雾相对适宜的条件范围,研究细水雾的特性参数对锂离子电池组灭火效果的影响.结果表明:在细水雾雾滴动能不变的情况下,随细水雾雾滴粒径增大,灭火时间先波动后增大,在细水雾粒径为50～100μm的工况下系统抑制锂离子电池火效果最佳,灭火时间最短,耗水量最少;水雾动量变化在一定区间内增加对锂电池灭火有增强效果,当雾滴速度足以穿越火焰时,增加水雾动量对灭火效果影响不大;在规定范围内喷雾强度越大,细水雾能够气化的数量越多,吸收的热量也越多,越有利于灭锂离子电池火灾.     

不同直径食用油池火燃烧特性对比试验研究

为探究食用油火灾的预防、探测及灭火技术,开展不同直径食用油池火燃烧试验,测量食用油油层温度、火焰及火羽流温度、质量损失速率、以及火焰高度等参数,分析食用油池火的燃烧特性,包括其被加热-自燃-燃烧的引燃过程和油层温度、火焰及火羽流温度、质量损失速率的变化规律;分析食用油池火燃烧速率随油池直径变化的规律,并结合理论公式计算不同油池直径对应的热释放速率。结果表明:食用油池火最大燃烧速率约为2. 3 mm/min;油池直径分别为25、40、55、70和85 cm的食用油池火对应的热释放速率分别为20、60、190、375和551 k W。     

细水雾灭火技术的研究

细水雾灭火技术主要通过汽化隔氧、冷却燃料和氧化剂以及吸收部分热辐射等效应与火相互作用,降低燃烧化学反应速率和火焰传播速率,达到控制和扑灭火灾的目的,不会产生“二次性环境污染”,可以达到火灾防治洁净化目标。为此,对细水雾抑制火灾的过程和机理进行了实验研究和数值模拟,以促进细水雾灭火技术的发展     

基于灰色关联分析的变压器油池火灭火有效性评估

为对比不同灭火系统扑灭变压器油池火灾有效性,提升变压器油池火灭火效能,从效能评估工具、灭火临界参数、行业法规中提取并确定变压器油池火灭火有效性评估指标集,包括3个观测变量,6个具体指标。采用Otsu’s算法处理火灾图像确定火焰面积,通过层次分析法确定各观测变量和具体指标权重,应用灰色关联法构建变压器油池灭火有效性评估模型。以水喷雾、细水雾、泡沫-水喷雾以及泡沫-细水雾扑灭变压器油池火为例,分别计算4种不同灭火系统下的灭火有效性。研究结果表明：灭火方案有效性为泡沫细水雾(1.000)>纯水细水雾(0.653)>泡沫水喷雾(0.447)>纯水水喷雾(0.333)。该评估模型可以将消防监测终端采集的消防大数据与人工智能技术有效结合,有助于提升变压器消防安全管理智能化水平。     

高高原机场油池火燃烧特性研究

为研究高高原机场特定环境中正庚烷油池火燃烧特性,考虑火灾受空气氧分压等因素影响,在康定高高原机场实验室利用ISO9705燃烧系统开展等效火灾油池的燃烧试验,重点分析热释放速率、燃烧速率、温度场分布和火焰辐射热通量等特性参数的变化规律。结果表明:燃烧速率方面,油池尺寸和单位面积燃烧速率近似呈线性变化;火场温度方面,受大气压力和空气密度影响,油池轴线最高温度较常压低,温升与经典羽流温升理论存在偏差;热辐射通量方面,通过曲线拟合方法得到油池尺寸与热辐射通量的关系式。     

细水雾灭油池火时各种影响因素的相对重要度分析

采用实验的方法并与理论分析相结合，对细水雾在扑灭B类火时，占主导地位的灭火机理进行了研究。实验中发现，当液体燃料的闪点相差较大时，其灭火机理往往不尽相同。并且当细水雾的雾特性相差较大时，在灭火中起主导作用的灭火机理常常也各有不同。因而那种单纯以雾滴的粒径分布作为细水雾扑灭燃料闪点较高的油池火时，雾滴的动量分布对细水雾的灭火有效性影响更大。为此，本文还建立了一个简单的模型，试图得到在这种火灾场景下，对细水雾灭火的临界动量要求。     

自然通风房间内细水雾与油池火作用的数值模拟

采用大涡模拟、混合物分数燃烧模型和欧拉-拉格朗日粒子运动描述法,对自然通风房间内细水雾与油池火焰作用过程进行数值模拟;探讨细水雾在火羽流的不同区域内的灭火机理;分析雾滴直径在自然通风条件下对细水雾灭火效果的影响。模拟结果表明:细水雾冷却热烟气层分为温度迅速降低和缓慢下降两个阶段;在间歇火焰区和浮力羽流区以及热烟气层主要发挥细水雾的蒸发冷却作用,在恒定火焰区则是蒸发冷却和隔氧窒息共同作用;着火区域封闭性较差时,直径较小的水雾系统的灭火效果较低。     

超细水雾抑制煤燃烧的模拟实验研究

为了研究超细水雾对煤燃烧的抑制效果,基于小尺寸空间抑制燃烧实验平台,研究了超细水雾对煤燃烧的抑制效果,计算在超细水雾作用下实验空间内部氧气、二氧化碳、一氧化碳体积分数的变化情况以及燃烧空间内不同部位的温度变化情况,并且与煤自由燃烧的情况做对比。研究表明超细水雾对煤燃烧的火灾发展过程有很好的抑制作用。研究结论对超细水雾应用于熄灭矿井煤炭火灾具有一定的指导意义     

Experimental study on fire suppression performance of the high pressure water mist in the engine room of an offshore platform

The total flooding application water mist system is a new type of environmentally-friendly fixed extinguishing system. The optimizing design can improve its fire extinguishing performance. At present, the water mist fire extinguishing system in the engine room of the offshore deepwater semi-submersible support platform has not attracted sufficient attention. In this paper, the water mist in the engine room of a deepwater semi-submersible support platform was studied. It contains the effect of water mist on the heat absorption and oxygen insulation of diesel pool fires. The applicable parameters of the water mist fire extinguishing system were also determined. Moreover, based on the shielding of the fire source in the engine room and the different requirements for water mist extinguishing parameters, a hierarchical multi-parameter combined high-pressure water mist fire extinguishing system was proposed. In the full-scale experimental engine room model, according to the fire extinguishing experiments for diesel pool fires with different areas, this kind of hierarchical multi-parameter water mist system is very effective on shielded and non-shielded fires. In addition, it is still effective even in a non-closed environment coupled with smoke exhausting.     

A study of the probability distribution of pool fire extinguishing times using water mist

Water mist, a replacement for Halon gaseous agents in fire fighting, has been studied for decades. However, the fire-extinguishing reliability of water mist is debated. For example, there are significant differences in extinguishing times between tests conducted under the same conditions, and water mists have difficulty extinguishing small fires. To date, no study of the probability distribution of extinguishing times has been reported. In this study a statistical analysis of the extinguishing time distribution of pool fires extinguished using water mist is presented. The fire sources were circular/square stainless steel pans with gasoline, diesel, ethanol or daqing RP-3 as fuel. Two types of extinguishing scenarios were observed. In one situation, the fire was extinguished via a blow off process, when the flames had not yet been suppressed. Flame cooling is the primary fire extinguishing mechanism; the mass loss rate and combustion heat of the fuel are two key factors. In the other situation, the fire was initially suppressed and subsequently extinguished after a long suppression stage. Surface cooling is the primary fire extinguishing mechanism; the flash point of the fuel is the key factor.     

Characteristics of large cooking oil pool fires and their extinguishment by water mist

Large cooking oil pool fires, occurring in industrial oil cookers, present a severe hazard to food processing plants due to their size and the large amount of hot oil involved. This paper reports a series of full-scale fire experiments conducted in a large industrial oil cooker mock-up. The characteristics of large cooking oil pool fires and the effect of oil depth and hood position in the oil cooker on fire growth were studied. The use of water mist for extinguishing large oil pool fires and their extinguishing performance under different discharge pressure and with different types of water mist systems were investigated. Experimental results showed that the cooking oil underwent a substantial expansion in volume during heating. The fires developed quickly once the oil auto-ignited. The fire growth rate was affected by the oil depth in the pan and the hood position in the oil cooker. The water mist fire suppression systems effectively extinguished large cooking oil fires and prevented them from re-igniting. Their extinguishing performance was determined by the type of water mist system, discharge pressure and hood position in the oil cooker.     

CO_2分析在含化学添加剂的细水雾灭火研究中的应用探讨

通过实验和计算证明CO2浓度分析是评价含添加剂细水雾灭火有效性的简单而有效方法。采用燃烧分析仪测定细水雾灭火实验过程中的CO2浓度,比较含不同添加剂细水雾和纯水细水雾在同一实验控制条件下的CO2浓度变化规律,利用CO2浓度变化规律判断含添加剂细水雾灭火的效率。根据上述规律,可从两方面比较细水雾的灭火效率:一是CO2的最高浓度。CO2达到的最大浓度小,则燃烧过程中的热释速率小或灭火时间短,说明细水雾抑制燃烧的效果较好。二是施加细水雾后CO2浓度变化率。CO2浓度变化率小,燃烧过程中的热释速率就小,说明细水雾抑制燃烧的效果较好。     

受限空间内细水雾与火相互作用的实验研究

细水雾灭火系统作为卤代烷系列灭火剂的替代产品之一，以其高效无毒、经济实用的优点，近年来在国际上研究得非常活跃。本文在受限空间内利用先进的材料热释放速率测量仪研究了细水雾与火的相互作用过程，并得到了以下结论：细水雾通过汽化吸热冷却燃料及氧化剂、体积膨胀隔氧以及吸收热辐射降低对燃料的热回馈等效应与火相互作用，达到控制和扑灭火灾的目的，在受限空间内汽化隔氧效应起着重要作用。     

不同喷射方式细水雾灭火效果的试验

细水雾的喷射方式对其灭火效果存在一定的影响。利用时间继电器控制细水雾灭火系统的启停,开展了连续式和脉冲式两种喷射方式的细水雾对开门与关门两种通风条件下不同燃料油池火分别进行抑制的试验研究。结果表明:在试验条件下,对于开门状态下连续式细水雾难以扑灭的汽油池火,脉冲式细水雾能显著提高灭火效果;对于连续式细水雾容易扑灭的柴油池火及关门状态下的汽油池火,脉冲式细水雾不能提高灭火效果,且灭火时间和用水量均有所增加;对于细水雾难以扑灭的酒精池火,连续式细水雾和脉冲式细水雾均未有效扑灭火焰。     

受限空间脉冲细水雾灭火数值模拟

为研究脉冲细水雾灭火效果和灭火机理,采用FDS软件对连续和脉冲细水雾熄灭受限空间油盘火进行了数值模拟。通过模拟和理论分析确定了脉冲细水雾周期为8 s开启、8 s暂停,并设置了冷却和窒息两种灭火条件,对两种细水雾熄灭不同尺寸的柴油池火进行了研究。结果表明:连续细水雾无法熄灭直径15 cm和20 cm的小尺寸油盘火,对直径25 cm中尺寸油盘火的灭火机理为冷却,对直径为30cm和35 cm大尺寸油盘火的灭火机理为窒息;脉冲细水雾能够熄灭不同尺寸的油盘火,且灭火效率高,火焰熄灭均发生在喷头暂停喷水期间,灭火机理为水雾蒸发稀释氧气而窒息。     

An experimental study on the burning rate of a continuously released n-heptane spill fire on an open water surface

Spill fires are common during oil product storage and transportation after a loss of containment. Since the burning fuel is moving and the fuel depth is quite shallow, the burning rate in a spill fire is different from that of a pool fire with a static burning zone. Unlike pool fires, which have been studied for decades and have well-established correlations for burning rate, research on spill fires is inadequate. In this paper, continuously released n-heptane spill fire experiments were conducted on open water surfaces with varying fuel discharge rates. The pool diameters were measured, and the spill fire burning rates were estimated based on a dynamic balance between fuel supply and combustion. The burning rates in n-heptane pool fires from the literature were reviewed and compared with the estimated burning rates in spill fires of the same dimension. The spill fire burning rate was found to be close to that in a pool fire during the initial burning phase but lower than that in a bulk burning pool fire and that in a “fuel-level-controlled” pool fire. The distinction between the burning rates of spill fires and pool fires is explained by the heat balance analysis of the fuel layer. A model for the spill fire burning rate was proposed accordingly. The results calculated with the presented model are closer to the measured data than those calculated with pool fire models.     

超细水雾抑制酒精火有效性实验研究

为了研究超细水雾对酒精火的抑制效果,通过搭建超细水雾抑制受限空间酒清火燃烧的小尺寸实验平台,利用基于质量损失速率的热释放速率计算方法,研究超细水雾与酒精火焰相互作用时,酒精火火焰的变化规律及酒精火的热释放速率,与此同时,采用高速摄像仪对火焰进行拍摄,利用Matlab图像处理程序对采集的火焰图片剖面进行处理.研究发现:施...