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Nitrogen as an environmentally friendly suppression agent for aircraft cargo fire safety 氮作为一种环保型灭火剂,对飞机货机的消防安全起着重要作用
IF 1.9 4区 工程技术 Q2 Engineering Pub Date : 2021-08-03 DOI: 10.1177/07349041211034456
M. Diakostefanis, S. Sampath, A. Dinesh, Rainer Beuermann, A. Malkogianni
Fire suppression systems in cargo compartments are a certification requirement for commercial aircraft safety. Halon production was banned and usage ends in 2040 according to Montreal Protocol for environmental reasons. This necessitates an alternative environmentally friendly agent. Quantitative analysis of nitrogen as agent established suitability of the suppression system. The Minimum Performance Standards specifies the qualification procedure of an agent through four scenarios – bulk load; containerised load; surface burning; and aerosol can explosion. Empirical sources from Airbus, independent computational fluid dynamics studies and small-scale cup-burner tests indicate suitability of nitrogen specific to aircraft cargo fire suppression. The nitrogen delivery system and the experimental apparatus are presented. Extensive commissioning tests verified instrumentation reliability. All the four scenarios were conducted at Cranfield University, in a replica of a wide-body aircraft cargo compartment. In a reduced oxygen environment (11%) obtained with nitrogen discharge, the aerosol can explosion tests were performed without any evidence of explosion or pressure increase beyond the expected baseline value. The surface burning scenario was completed successfully and passed the Minimum Performance Standard criteria. The maximum average temperature was found to be 220°C (limit – 293°C). All the scenarios passed the Minimum Performance Standard criteria for indicating successful prevention of Class B fire re-ignition. Similarly, the containerised and bulk-load scenarios obtained results that passed the Minimum Performance Standard criteria for successfully maintaining continued fire suppression for a specified period of time. The maximum average temperature in containerised-load fire scenario was found to be 210°C (limit – 343°C) and in bulk-load scenario was 255°C (limit – 377°C). Additional qualification criteria and system design are presented in this article according to the Minimum Performance Standard format. This work can be extended to introduce standard testing for safety critical systems, such as engine bay and lithium-ion fires.
货舱中的灭火系统是商用飞机安全的认证要求。根据《蒙特利尔议定书》,由于环境原因,哈龙的生产被禁止,使用将于2040年结束。这就需要另一种环保剂。氮作为药剂的定量分析确定了抑制系统的适用性。《最低性能标准》规定了代理商在四种情况下的资格鉴定程序——散装;集装箱装载;表面燃烧;气溶胶会爆炸。来自空中客车公司的经验来源、独立的计算流体动力学研究和小型杯形燃烧器测试表明,特定于飞机货物灭火的氮气适用性。介绍了氮气输送系统和实验装置。广泛的调试测试验证了仪器的可靠性。所有四个场景都是在克兰菲尔德大学的一个宽体飞机货舱的复制品中进行的。在氮气排放获得的低氧环境(11%)中,在没有任何爆炸或压力增加超过预期基线值的证据的情况下进行了气溶胶罐爆炸试验。表面燃烧方案已成功完成,并通过了最低性能标准标准。发现最高平均温度为220°C(极限-293°C)。所有场景都通过了最低性能标准,表明成功预防了B类火灾的再次点燃。同样,集装箱化和散装场景获得的结果通过了在指定时间内成功维持持续灭火的最低性能标准。集装箱装载火灾场景中的最高平均温度为210°C(极限343°C),散装装载场景中的最大平均温度为255°C(限制377°C。根据最低性能标准的格式,本文提出了额外的资格标准和系统设计。这项工作可以扩展到引入安全关键系统的标准测试,如发动机舱和锂离子火灾。
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引用次数: 1
A review on fire suppression by fire sprinklers 洒水车灭火技术研究进展
IF 1.9 4区 工程技术 Q2 Engineering Pub Date : 2021-07-24 DOI: 10.1177/07349041211013698
Shehu A Abdulrahman, K. Chetehouna, A. Cablé, Ø. Skreiberg, M. Kadoche
Water spray remains the most effective, environment-friendly and economical way of fighting accidental or unwanted fires, and this is largely due to its thermal characteristics. The mechanism of fire suppression by sprinkler water sprays is influenced by numerous factors, which have been the focus of years’-long and on-going research studies to improve its extinguishing performances. A comprehensive review study was carried out in this study to assess the level of technological know-how and current state of research in the field. A total of 2473 published articles spanning 50 years (i.e. 1970–2020) were systematically collected and analysed, whereby more than 100 relevant articles were selected and integrated in the discussion. In particular, the review focuses on research relating to the interactions of sprinkler sprays with flame, fire plume and hot surfaces, aiming to provide a better understanding of the phenomena involved in fire suppression.
喷水仍然是最有效、最环保、最经济的方式来扑灭意外或不必要的火灾,这主要是由于它的热特性。喷水灭火的灭火机理受多种因素的影响,为提高其灭火性能,多年来一直是人们研究的重点。在这项研究中进行了一项全面的审查研究,以评估该领域的技术知识水平和研究现状。系统地收集和分析了50年(即1970-2020年)共2473篇已发表的文章,从中选择了100多篇相关文章并整合到讨论中。该综述特别关注与喷雾器喷雾剂与火焰、火羽和热表面相互作用有关的研究,旨在更好地理解灭火过程中涉及的现象。
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引用次数: 6
Experimental study on the flame extension and risk analysis of a diffusion impinging flame in confined compartment 密闭空间内扩散冲击火焰扩展试验研究及危险性分析
IF 1.9 4区 工程技术 Q2 Engineering Pub Date : 2021-07-01 DOI: 10.1177/07349041211015766
Aijuan Wang, B. Manescau, K. Chetehouna, S. Rudz, L. Lamoot
In this work, an experimental investigation on a diffusion impinging flame in a confined compartment was performed. The objective was to study the influence of confinement on the behavior of a flame impinging the ceiling and to deduce the auto-ignition risk of the smoke produced in the confined compartment. For this, configurations with five confinement levels were constructed by the condition of windows and/or door in the compartment and the variation of the heat release rates was made between 0.5 and 18.6 kW. To evaluate the flame morphology and flame extension length, an image processing method based on the direct linear transformation algorithm and the fire segmentation algorithm was adopted. From the experimental data, it was shown that the heat release rate of 4.6 kW presents a critical value for the flame extension in confined configurations, which corresponds to the equivalence ratio of the enclosure greater than 1, highlighting an under-ventilated environment. In addition, an auto-ignition risk analysis of smoke with unburnt gas in the compartment was carried out. The concentration and temperature of these gases were compared to the lower flammability limits and the auto-ignition temperature. It was observed that there was auto-ignition risk of the smoke under the ceiling, especially in the confined compartment of equivalence ratio greater than 1. Under these conditions, it is possible to have a fire spread to another compartment.
在这项工作中,对有限空间中的扩散撞击火焰进行了实验研究。目的是研究限制对火焰撞击天花板行为的影响,并推断限制室内产生的烟雾的自燃风险。为此,根据隔间内窗户和/或门的条件,构建了具有五个限制水平的配置,热释放率的变化在0.5到18.6之间 为了评估火焰形态和火焰延伸长度,采用了基于直接线性变换算法和火焰分割算法的图像处理方法。从实验数据来看,4.6 kW是受限配置中火焰扩展的临界值,对应于大于1的外壳当量比,突出了通风不足的环境。此外,还对车厢内有未燃烧气体的烟雾进行了自燃风险分析。将这些气体的浓度和温度与可燃性下限和自燃温度进行比较。据观察,天花板下的烟雾存在自燃风险,尤其是在当量比大于1的密闭隔间中。在这种情况下,火灾有可能蔓延到另一个隔间。
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引用次数: 3
Household cooking oil use and its bearing on fire safety 家用食用油的使用及其与消防安全的关系
IF 1.9 4区 工程技术 Q2 Engineering Pub Date : 2021-05-10 DOI: 10.1177/07349041211012994
M. Spearpoint, C. Hopkin
Cooking oil fires present a reasonable worst-case hazard when considering thermal radiation to occupants close to a kitchen hob/cooktop. Shallow or deep frying, the activity frequency and the oil volume may contribute to the risk. A review of cooking oil use is presented via consumer purchasing habits, studies on the health effects of cooking with oil and statistics related to the disposal of cooking oil waste. An online survey provides further data on current cooking practices. Olive oil, vegetable oil or pure sunflower appear to be the most common types. Results suggest that cooking on a hob occurs 4 times per month for deep frying and 17 times per month for shallow frying. A design value of 250 mL is advocated for all frying activities with a frequency of 11 times per month. Design volumes of 2.5 L and 150 mL are proposed for deep and shallow frying, respectively.
当考虑到厨房灶台/炉灶面附近的居住者受到热辐射时,食用油火灾在最坏的情况下会造成合理的危险。浅炸或油炸、活动频率和油量可能会增加风险。通过消费者的购买习惯、对用油烹饪对健康影响的研究以及与食用油废物处理相关的统计数据,对食用油的使用进行了综述。一项在线调查提供了有关当前烹饪实践的进一步数据。橄榄油、植物油或纯向日葵似乎是最常见的类型。结果表明,油炸每月在滚刀上烹饪4次,浅炸每月烹饪17次。设计值250 提倡对所有油炸活动使用mL,频率为每月11次。2.5的设计体积 L和150 mL分别用于油炸和浅油炸。
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引用次数: 4
Numerical assessment for aircraft cargo compartment fire suppression system safety 飞机货舱灭火系统安全性的数值评估
IF 1.9 4区 工程技术 Q2 Engineering Pub Date : 2021-04-27 DOI: 10.1177/07349041211003208
Yifang Xiong, M. Diakostefanis, A. Dinesh, S. Sampath, T. Nikolaidis
Fire on board an aircraft cargo compartment can lead to catastrophic consequences. Therefore, fire safety is one of the most important considerations during aircraft design and certification. Conventionally, Halon-based agents were used for fire suppression in such cases. However, an international agreement under the Montreal Protocol of 1994 banned further production of Halon and several other halocarbons considered harmful to the environment. There is therefore a requirement for new suppression agents, along with suitable system design and certification. This article aims to describe the creation of a mechanism to validate a preliminary design for fire suppression systems using Computational Fluid Dynamics and provide further guidance for fire suppression experiments in aircraft cargo compartments. Investigations were performed for the surface burning fire, one of the fire testing scenarios specified in the Minimum Performance Standard, using the numerical code Fire Dynamics Simulator. This study investigated the use and performance of nitrogen, a potential replacement for Halon 1301, as an environmentally friendly agent for cargo fire suppression. Benchmark fires using the pyrolysis model and fire design model were built for the surface-burning fire scenario. Compared with experiment results, the two Computational Fluid Dynamics models captured the suppression process with high accuracy and displayed similar temperature and gas concentration profiles. Fire consequences in response to system uncertainties were studied using fire curves with various fire growth rates. The results suggested that using nitrogen as a fire suppression agent could achieve a lower post-suppression temperature compared to a Halon 1301-based system. It can therefore be considered as a potential candidate for aircraft cargo fire suppression. Such work will feed directly into system safety assessments during the early design stages, where analyses must precede testing. Future work proposed for the application of this model can be extended to other fire scenarios such as buildings, shipping, and surface transport vehicles.
飞机货舱发生火灾可能导致灾难性后果。因此,消防安全是飞机设计和认证过程中最重要的考虑因素之一。在这种情况下,通常使用基于哈龙的灭火剂进行灭火。然而,1994年《蒙特利尔议定书》下的一项国际协议禁止进一步生产哈龙和其他几种被认为对环境有害的卤代烃。因此,需要新的抑制剂以及合适的系统设计和认证。本文旨在描述使用计算流体动力学验证灭火系统初步设计的机制的创建,并为飞机货舱中的灭火实验提供进一步的指导。使用数字代码“火灾动力学模拟器”对地表燃烧火灾进行了调查,这是《最低性能标准》中规定的火灾测试场景之一。这项研究调查了氮的使用和性能,氮是哈龙1301的潜在替代品,是一种环保的货物灭火剂。针对地面燃烧火灾场景,使用热解模型和火灾设计模型建立了基准火灾。与实验结果相比,两个计算流体动力学模型高精度地捕捉到了抑制过程,并显示出相似的温度和气体浓度分布。利用不同火灾增长率的火灾曲线研究了系统不确定性对火灾后果的影响。结果表明,与基于Halon 1301的系统相比,使用氮气作为灭火剂可以实现更低的灭火后温度。因此,它可以被视为飞机货物灭火的潜在候选者。此类工作将直接纳入早期设计阶段的系统安全评估,在早期设计阶段,必须在测试之前进行分析。为应用该模型而提出的未来工作可以扩展到其他火灾场景,如建筑、航运和地面运输车辆。
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引用次数: 2
Towards real-time fire data synthesis using numerical simulations 利用数值模拟实现实时火灾数据合成
IF 1.9 4区 工程技术 Q2 Engineering Pub Date : 2021-04-16 DOI: 10.1177/0734904121993449
W. Jahn, Frane Sazunic, C. Sing-Long
Synthesising data from fire scenarios using fire simulations requires iterative running of these simulations. For real-time synthesising, faster-than-real-time simulations are thus necessary. In this article, different model types are assessed according to their complexity to determine the trade-off between the accuracy of the output and the required computing time. A threshold grid size for real-time computational fluid dynamic simulations is identified, and the implications of simplifying existing field fire models by turning off sub-models are assessed. In addition, a temperature correction for two zone models based on the conservation of energy of the hot layer is introduced, to account for spatial variations of temperature in the near field of the fire. The main conclusions are that real-time fire simulations with spatial resolution are possible and that it is not necessary to solve all fine-scale physics to reproduce temperature measurements accurately. There remains, however, a gap in performance between computational fluid dynamic models and zone models that must be explored to achieve faster-than-real-time fire simulations.
使用火灾模拟综合火灾场景的数据需要迭代运行这些模拟。因此,对于实时合成,需要比实时模拟更快的速度。在本文中,根据不同的模型类型的复杂性对其进行评估,以确定输出的准确性和所需计算时间之间的权衡。确定了实时计算流体动力学模拟的阈值网格大小,并评估了通过关闭子模型来简化现有现场火灾模型的意义。此外,还引入了基于热层能量守恒的两个区域模型的温度校正,以考虑火灾近场温度的空间变化。主要结论是,具有空间分辨率的实时火灾模拟是可能的,并且不需要解决所有精细尺度的物理问题来准确再现温度测量结果。然而,计算流体动力学模型和区域模型之间的性能仍然存在差距,必须对其进行探索,以实现比实时火灾模拟更快的速度。
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引用次数: 0
Brominated flame-retardant composition in firefighter bunker gear and its thermal performance analysis 消防员方舱装备中溴化阻燃剂的组成及其热性能分析
IF 1.9 4区 工程技术 Q2 Engineering Pub Date : 2021-04-15 DOI: 10.1177/07349041211001296
Vincent N Mokoana, J. Asante, J. Okonkwo
Firefighting bunker gear is manufactured from flame-retardant materials, which resist ignition and delay flame spread. However, concerns have been emerging on the potential harmful effects of some flame retardants (FRs) commonly used in flame-retarding materials, particularly the brominated flame retardants. This study investigated the presence of flame retardants in bunker gear, particularly polybrominated diphenyl ethers and their congeners in the garments, and evaluated their impact on thermal performance. X-ray fluorescence spectroscopy was used to ascertain the presence of bromine as a possible indicator for brominated flame retardants. X-ray fluorescence results indicated the presence of Br in all samples, ranging from 444 to 20,367 µg/g. Further analysis via gas chromatography–mass spectrometry was done on samples. Brominated flame retardants, particularly polybrominated diphenyl ethers and hexabromocyclododecane, were detected in all samples with concentrations ranging from 261.61 to 1001.77 µg/g and 0.01 to 0.07 µg/g, respectively. The cone calorimeter was used, with 50 and 75 kW/m2 heat fluxes, to investigate the impact of the brominated flame-retardant concentrations, if any, on thermal performance. New bunker garments, particularly those with lower Br and brominated flame-retardant concentrations, were observed to have higher thermal performance.
消防舱齿轮采用阻燃材料制造,具有抗着火、延缓火焰蔓延的作用。然而,阻燃材料中常用的一些阻燃剂,特别是溴化阻燃剂的潜在有害影响已引起人们的关注。本研究调查了燃料箱装备中阻燃剂的存在,特别是多溴联苯醚及其在服装中的同系物,并评估了它们对热性能的影响。用x射线荧光光谱法确定溴的存在,作为溴化阻燃剂的可能指示剂。x射线荧光结果表明,所有样品中都存在Br,范围为444至20,367µg/g。通过气相色谱-质谱法对样品进行进一步分析。在所有样品中检测到溴化阻燃剂,特别是多溴联苯醚和六溴环十二烷,浓度分别为261.61至1001.77µg/g和0.01至0.07µg/g。使用热流为50和75 kW/m2的锥形量热计来研究溴化阻燃剂浓度(如果有的话)对热性能的影响。新的防弹衣,特别是那些含有较低Br和溴化阻燃剂浓度的防弹衣,被观察到具有更高的热性能。
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引用次数: 3
Development of a pyrolysis model for oriented strand board. Part I: Kinetics and thermodynamics of the thermal decomposition 定向刨花板热解模型的建立。第一部分:热分解的动力学和热力学
IF 1.9 4区 工程技术 Q2 Engineering Pub Date : 2021-03-01 DOI: 10.1177/0734904120982887
Junhui Gong, Hong Zhu, Hongen Zhou, S. Stoliarov
Oriented strand board is a widely used construction material responsible for a substantial portion of the fire load of many buildings. To accurately model the response of oriented strand board to fire, thermogravimetric analysis, differential scanning calorimetry, and microscale combustion calorimetry tests were carried out to construct a thermal decomposition model using a numerical solver, ThermaKin, and a hill climbing optimization algorithm. The model included a single-step water vaporization reaction and four consecutive reactions representing thermal decomposition of organic constituents of oriented strand board. The experiments and modeling revealed that the first two of the four reactions are endothermic, while the last two are exothermic. The net heat of decomposition was found to be near zero. The heat capacities of condensed-phase species and heats of combustion of evolved gases were also determined. The heats of combustion were found to vary over the course of decomposition—the trend captured by the model. Development of a complete pyrolysis model for this material will be a subject of Part II of this work.
定向刨花板是一种广泛使用的建筑材料,承担了许多建筑物的很大一部分火灾负荷。为了准确地模拟定向刨花板对火灾的响应,采用热重分析、差示扫描量热法和微尺度燃烧量热法测试,利用数值求解器ThermaKin和爬坡优化算法构建了定向刨花板的热分解模型。该模型包括一个单步水蒸发反应和四个连续反应,代表定向刨花板有机成分的热分解。实验和模拟结果表明,前两个反应为吸热反应,后两个反应为放热反应。发现净分解热接近于零。测定了凝析相物质的热容和放出气体的燃烧热。燃烧热在分解过程中发生变化,这是模型捕捉到的趋势。该材料的完整热解模型的开发将是本工作第二部分的主题。
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引用次数: 10
An analysis of the WTC fires using CIB correlations and simple modeling 利用CIB相关性和简单建模分析WTC火灾
IF 1.9 4区 工程技术 Q2 Engineering Pub Date : 2021-02-20 DOI: 10.1177/0734904121989670
J. Quintiere
CIB correlations for compartment burning rates and average gas temperatures are examined for accuracy, utility, and generality. The results are applied to modeling the fire on 9/11 in WTC 1. Specific information is used from the NIST investigation. It is demonstrated that simple heat transfer modeling can predict the truss steel rod temperatures for the E119 tests of WTC done by NIST. The CIB temperature correlation and steel truss modeling are used to predict burning conditions for the WTC 1 96th floor fire and compared to the NIST results. Here a consideration of fuel loads from 20 to 40 kg/m2 was considered compared to just 20 used by NIST. The results suggest that the fully insulated truss bar temperatures would achieve higher values for higher fuel loads. A critical steel truss temperature of 650°C could support failure of the trusses as a theory for the collapse of the towers.
对隔间燃烧速率和平均气体温度的CIB相关性进行了准确性、实用性和通用性检验。将计算结果应用于WTC1的9/11火灾模型。具体信息来自NIST调查。研究表明,简单的传热模型可以预测NIST进行的WTC E119试验的特拉斯钢杆温度。CIB温度相关性和特拉斯钢模型用于预测WTC 1 96层火灾的燃烧条件,并与NIST的结果进行了比较。此处考虑20至40的燃料负荷 kg/m2,而NIST仅使用20。结果表明,完全绝缘的特拉斯杆的温度在较高的燃料负荷下会达到更高的值。临界温度为650°C的特拉斯钢可以支持桁架的破坏,作为塔架倒塌的理论。
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引用次数: 0
The character of residential cooktop fires 住宅炉灶面火灾的特点
IF 1.9 4区 工程技术 Q2 Engineering Pub Date : 2021-01-08 DOI: 10.1177/0734904121990392
Yue Hu, Jian Chen, M. Bundy, A. Hamins
A series of experiments was conducted to investigate the global preignition and combustion characteristics of corn oil heated in 9.7 to 26 cm diameter pans by a residential electric-coil element cooktop. For comparison, torch-ignited gasoline, heptane, and corn oil experiments were conducted in the same configuration except without the heating element energized. Heating oil on a typical electric cooktop leads to vaporization and generation of an aerosol cloud followed by autoignition. The evolution of the light-extinction coefficient before autoignition is measured and shown to be related to the pan diameter and initial fuel mass. Continued heating leads to enhanced vaporization of the burning oil and growing fires with the peak heat release rate, radiative heat flux, radiative fraction, and peak flame height larger than the gasoline fires regardless of pan diameter. CO and soot yields, and the CO/CO2 ratio are measured to decrease with pan diameter.
通过一系列实验研究了9.7~26年加热玉米油的全局预燃和燃烧特性 cm直径的锅,由住宅用线圈元件炉灶面提供。为了进行比较,火炬点燃的汽油、庚烷和玉米油实验在相同的配置中进行,不同之处在于加热元件未通电。在典型的电炉上加热油会导致蒸发并产生气溶胶云,然后自燃。测量了自燃前消光系数的演变,并表明其与锅体直径和初始燃料质量有关。持续加热会导致燃烧的油的蒸发增强,并导致火灾加剧,无论锅体直径如何,峰值热释放率、辐射热通量、辐射分数和峰值火焰高度都大于汽油火灾。CO和烟炱产量以及CO/CO2比率被测量为随着盘直径而减小。
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引用次数: 5
期刊
Journal of Fire Sciences
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