受限空间火灾环境固体可燃物热释放速率模拟研究

对PMMA和松本两种典型的固体可燃物，采用基于耗氧原理的燃烧热释放速率测量方法，利用锥型量热计系统，在不同外加辐射热作用下测量了热释放率。分析PMMA与松木燃烧过程的异同及外加辐射热对固体可燃物热释放速率的影响。     

细水雾熄灭K类火灾的全尺寸模拟实验

利用ISO 9705全尺寸多功能热释放速率测试仪在开放空间研究了细水雾作用下K类火灾的发展过程,实验中对细水雾作用下食用油火的温度、热释放速率及烟气的主要特性参数变化规律进行了测量与研究,分析了预燃时间对灭火有效性的影响,系统地阐述了细水雾作用下K类火灾关键特性参数的变化规律．实验发现,细水雾可以有效地抑制K类火灾的发展,在其作用下火焰温度及热释放速率快速降低,并可以有效地冲刷烟气,降低一氧化碳及二氧化碳的浓度,提高氧气的浓度及火场能见度．同时利用稳定火源热释放速率模型计算了K类火灾发展阶段的热释放速率,与实验测量结果比较发现,模型可准确地预测K类火灾发展阶段的热释放速率的变化规律．     

细水雾作用下火灾烟气典型特性参数的变化规律

利用ISO 9705全尺寸多功能热释放速率测试仪研究细水雾作用下火灾烟气的消光系数、质量密度及辐射热通量等特性参数的变化规律,通过改变细水雾工作压力、喷头种类和喷头数量等参数研究雾滴粒径、喷雾强度等对烟气特性参数的影响规律.确定了受限空间通风助燃和熄灭火焰的临界速率.实验发现,火源热释放速率是影响烟气特性参数变化规律的主要内在因素.研究结果为细水雾技术用于火灾烟气抑制提供了科学的参考依据.     

细水雾对油池火热释放速率影响的初步研究

热释放速率是反映火场规模与发展的最重要的基础参数，利用ISO9705实验台进行细水雾灭火有效性的影响因素及相关机理研究，不仅能营造出一个真实的室内火灾环境，而且能够得到火场的热释放速率。对汽油池火的初步实验表明：热释放速率曲线能直接反映出细水雾对火源的作用；细水雾作用下燃烧总的热释放量减少很大；开启水雾的时间不同，细水雾对热释放速率峰值的削减程度不同。     

细水雾释放策略对大容量三元锂离子电池热失控火灾抑制效果的实验研究

动力电池中,大容量三元锂离子电池产量大、热失控危险性高,使用细水雾抑制其热失控火灾的研究受到广泛关注。本文以150 Ah大容量三元锂离子电池为研究对象,使用10 MPa细水雾分别采取连续释放策略和脉冲释放策略进行热失控火灾抑制实验,对比分析不同释放时间、脉冲周期、占空系数等参数对热失控行为、温度及产热速率等实验结果的影响,结果表明：相比普通容量的锂离子电池,大容量三元锂离子电池的热失控过程会反复发生多次更为剧烈的燃烧行为,温升速率增幅明显,但细水雾对其仍有较好的火灾抑制效果,且释放时间越长,灭火效果与冷却效果越好,但连续释放策略仍存在复燃现象,且随着释放时间的增加,冷却效率的增幅逐渐趋缓。针对大容量三元锂离子电池,脉冲释放策略的热失控火灾抑制能力优于连续释放策略,其能够快速扑灭明火且不发生复燃,有效降低了产热速率和电池表面最高温度。在本文条件下,耗水量为10 L、周期为10 s的脉冲细水雾,在占空系数为0.3时存在冷却效果的实验最优值,此时的脉冲释放与相同耗水量下的连续释放相比,产热速率下降了28%,电池表面最高温度下降了176℃。本文可为大容量三元动力电池系统的灭火设施设计提供参考。     

外部热辐射对材料燃烧性能影响的实验研究

采用基于耗氧量原理的锥形量热计对木材、PVC以及聚氨酯泡沫塑料在不同热辐射条件下的热释放速率、平均释热速率、点燃时间、CO／C02生成率和烟气的减光性等燃烧特性进行了研究。实验结果表明，不同材料表现出不同的点燃性、热释放速率及烟气生成特征，并进行了初步的理论探讨。     

细水雾作用下原木楞堆燃烧特性的实验研究

在大尺寸实验室内,就细水雾抑制受限空间楞堆燃烧的有效性及影响因素进行实验研究。对楞堆火的初步实验表明:在细水雾的作用下楞堆火温度和热释放速率快速降低,且雾通量大的细水雾灭楞堆火更迅速,前期楞堆火更易被扑灭;细水雾汽化程度越高,在楞堆火上方漂浮、滞留时间越长,隔氧气作用就越明显,而雾通量太大则影响细水雾汽化效果。     

废菌棒燃烧特性研究

本文利用热重分析仪对废菌棒的燃烧特性进行了相关研究,分析了废菌棒的热解过程、升温速率对热解过程的影响、挥发分热力特性和氮释放特性,得出了废菌棒热解表观活化能,并研究了典型煤种掺混废菌棒后的着火特性。     

典型壁面装饰材料的热释放速率模型

根据顺流火蔓延理论推导了适用于ISO 9705墙角火实验的壁面材料火蔓延的热释放速率数学模型,考虑到材料厚度对热释放速率的影响,在模型推导过程中引入了一个与材料厚度相关的参数α,同时在小尺寸实验得到的材料火灾特性数据基础上,利用发展出来的热释放速率模型,对4种不同厚度胶合板的全尺寸热释放速率进行预测,并将预测结果与全尺寸实验结果进行比较.结果表明,本文建立的数学模型能够较好地预测较厚材料的热释放速率变化趋势.     

超细水雾抑制受限空间木材燃烧的实验研究

基于木材是火灾中常见的可燃物之一,通过搭建超细水雾抑制受限空间木材燃烧的小尺寸实验平台,研究了超细水雾抑制受限空间木材燃烧的有效性及影响因素.施加超细水雾后,木材的热释放速率和O2的下降速率增大,CO2的生成量增大到固定值时逐渐趋于平稳,这表明超细水雾可以有效降低木材的热释放速率,抑制木材的燃烧.超细水雾抑制木材燃烧的效果依赖于雾通量、预燃时间、施加时间等因素.雾通量充足时预燃时间越长,火焰越容易熄灭;雾通量不足时,超细水雾无法抑制木材的燃烧;预燃时间一定时,雾通量越大,超细水雾抑制木材火焰的效果越好;雾通量和预燃时间一定时,施加超细水雾的时间越长,木材表面越不易有阴燃现象,抑制木材火焰的效果越好.     

Experimental study on the interaction of fine water spray with liquid pool fires

InhoductionThe use of Ane water spray tO suPPress andextingush fires is one POtential candidate for halonrePlat. APPlications CUrrently indsde thesuPPression of dust exPlosion, solid and liquld fuelcOmbushon wdri cotheed sPaces, and fire withineleCtrical panels and so on. Fine wate sPray may Providemor effeehve fire sUPPrssion than new gaseousflooding agats in aPPlications such as deeP-seated thes,Where the coollng caPwi and penethaon of watedropets reach the base of fires. Another …     

Experimental and numerical study of the effects of nanoparticles on pyrolysis of a polyamide 6 (PA6) nanocomposite in the cone calorimeter

A large number of studies using the cone calorimeter showed that nanoparticles used even in small quantities (e.g. 3 wt.%) improve fire retardancy by reducing significantly the heat release rate/mass loss rate. The improved fire retardancy by nanocomposites has been attributed usually to the formation of a surface layer as a result of accumulation of nanoparticles on top of the virgin polymer because this surface layer not only acts as mass and thermal barriers to the polymer underneath but primarily increases surface radiation losses as the surface temperature increases. Various theories have been proposed for qualitatively explaining the mechanism of nanoparticles action, including mainly (a) gasification of polymer and precipitation of nanoparticles, (b) migration of nanoparticles towards the surface and (c) nanoconfinement. However, quantitative investigation on the effects of nanoparticles on pyrolysis has never been undertaken. In this work, square samples of a polyamide 6 (PA6) nanocomposite were tested in the cone calorimeter under different heat fluxes. By combining the experimental mass loss data and numerical calculations, a novel approach is developed to quantify the effects of nanoparticles and subsequently to predict pyrolysis of the PA6 nanocomposite at different heat fluxes and thicknesses, in good agreement with the experimental data.     

Study of the combustion efficiency of polymers using a pyrolysis–combustion flow calorimeter

The combustion efficiency of various polymeric materials was studied using a pyrolysis–combustion flow calorimeter (PCFC). Decreasing the combustion temperature in a PCFC leads to partial combustion and lower heat release rates. Combustion efficiency versus combustion temperature was modeled using a phenomenological equation and model parameters were related to the chemical structures of eight pure polymers. The flame inhibition effect was evaluated for two classical approaches in flame retardancy by plotting the combustion efficiency versus the combustion temperature. In the first one (the reactive approach), polystyrenes with different chemical groups substituted on the aromatic ring were studied. In the second one (the additive approach), three well-known flame retardants were incorporated into an ABS matrix: ammonium polyphosphate, tetrabromobisphenol A (TBBA), and a TBBA/antimony trioxide system. Results confirm the flame inhibition effect of halogenated compounds in both approaches. Finally, a correlation between peaks of heat release rate (pHRR) in a cone calorimeter and in a PCFC was attempted. Predicting pHRR in a cone calorimeter using a PCFC appears possible when no barrier effect is expected, if PCFC tests are carried out at a precise combustion temperature, for which the combustion efficiencies in both tests are the same.     

Fuel Load and Peak Heat Release Rate Correlations in Post-Flashover Room Fires

Flashover might occur rapidly as a consequence of non-accidental building fires. Response of the stored combustible items (being ignited and burned) should be studied carefully in such developed fires, which are ventilation-controlled. Air supply rate and heat fluxes acting at the materials would affect burning of the combustibles. A wide range of peak heat release rates with different fire durations results under different heat fluxes. The amount of combustibles denoted by fire or fuel load commonly adopted to quantify fire risks is no longer the key point in generating the heat release rate. A room with a large fire load may not give high heat release rates if the air supply is inadequate, or if the radiant heat flux is low. In this article, correlation of the peak heat release rate in burning the material under flashover with the fire load of the combustibles with adequate ventilation will be investigated. Data compiled from full-scale burning tests on well-developed room fires with steady burning are used to deduce a linear correlation between the possible peak heat release rate and the fire load density under adequate ventilation conditions.     

Optimization of pyrolysis properties using TGA and cone calorimeter test

The present paper describes an optimization work to obtain the properties related to a pyrolysis process in the solid material such as density, specific heat, conductivity of virgin and char, heat of pyrolysis and kinetic parameters used for deciding pyrolysis rate. A repulsive particle swarm optimization algorithm is used to obtain the pyrolysis-related properties. In the previous study all properties obtained only using a cone calorimeter but in this paper both the cone calorimeter and thermo gravimetric analysis (TGA) are used for precisely optimizing the pyrolysis properties. In the TGA test a very small mass is heated up and conduction and heat capacity in the specimen is negligible so kinetic parameters can first be optimized. Other pyrolysis-related properties such as virgin/char specific heat and conductivity and char density are also optimized in the cone calorimeter test with the already decided parameters in the TGA test.     

管道内甲烷火焰穿越水雾区的传播特性

利用自行设计的火焰传播实验系统研究了甲烷火焰穿越水雾区的传播现象；运用数字摄像、光电测速和温度测量等技术研究了不同水雾条件下的甲烷火焰传播速度、火焰阵面轨迹及火焰结构特性。结果发现：水雾与甲烷火焰作用后，火焰颜色明显变红。水雾量较小时，甲烷火焰会被加速；水雾量增大到一定值后，甲烷火焰会在水雾区某一位置滞留一段时间，随后火焰再加速传播或熄灭(对应更高的水雾量)。分析认为这种现象的出现与水雾在甲烷火焰区的吸热、蒸发膨胀和化学阻化等物理化学综合效应有关。     

喷水排烟作用下孤岛火灾行为及烟气运动实验

针对大空间内孤岛火灾安全集中讨论的焦点问题,通过全尺寸实验的方法研究了喷水排烟作用下大空间内孤岛火灾行为及烟气运动过程.分别设置不同火源功率、有无排烟喷水、不同排烟量、不同喷头类型及工作压力等条件而开展了全尺寸的对比性实验,并理论分析了排烟和喷水存在情况下的室内火灾动力学平衡的变化.结果表明:无排烟喷水时孤岛火灾增长迅速,在1.3 MW时可达到轰燃温度;不同喷头类型时孤岛内火灾行为特征及灭火规律表现不同;高速水雾喷头喷射会扩展羽流区半径及加强烟气分界面热分层失稳;喷头类型是灭火关键因素,增加喷头工作压力和排烟量可以降低室内温度,但效果不明显;规范设计孤岛排烟量(20 ACH)和喷水条件(标准喷头、0.05 MPa)存在一定的不足.全尺寸实验验证了排烟喷水作用可以有效地控制孤岛火灾对大空间影响.     

大空间内火灾烟气充填研究

分析了烟气在大空间建筑内的充填情况,得到了不同火源下的烟气填充计算模型,并在大空间实验厅内进行了全尺寸油池火对比试验,试验结果表明,烟气在火空间内的温度并不高,但烟气层下降速度很快,计算结果和试验结果对比表明,在大空间内仍可利用火灾区域模拟方法计算烟气的运动。对于池火,其计算模型的选择应根据火源的大小来确定。