Flame regime estimations of gasoline explosion in a tube

Flame regime of gasoline-air mixture explosion is related to chemical reaction, turbulent flow and heat and mass transfer. Experimental data of gas velocity, pressure and flame temperature of gasoline-air mixture explosion in a tube at the equivalence ratio of 0.72, 1.00 and 1.28 were preliminarily acquired. Then, fluctuating velocities, overpressures, and burned and unburned gas temperatures at early stage (50 ms), intermediate stage (150 ms) and last stage (250 ms) in three explosions were determined through the analysis of the experimental data. Finally, the Damköhler number and Reynolds number of the early, intermediate and late stage were calculated respectively, and the flame regimes for each stage were estimated through the Damköhler number vs. Reynolds number diagram. Results show that all the flames at early, intermediate and late stage of the three explosions have the same regime of flamelets-in-eddies. The conclusions can provide some useful references for further study of the flame regime and the numerical analysis model selection of gasoline-air mixture explosion.     

珠三角表层沉积物的有机碳及其与卤系阻燃剂的关系

测定了珠江三角洲130个表层沉积物中总有机碳(TOC)和10类卤系阻燃剂(HFRs)的含量,并探讨了TOC与HFRs之间的关系.结果表明:珠三角表层沉积物TOC范围为0.16％～5.76％,平均值为1.25％,呈现明显的空间变化.在工业化程度较高的东莞和广州,沉积物中HFRs与TOC有显著的相关性,而西江和珠江口沉积物中HFRs与TOC的相关性较差,可能与珠江三角洲水动力过程、电子垃圾拆解活动和HFRs不同的来源有关.     

轰燃后火焰的辐射热通量计算

轰燃后火焰的热辐射危害，是目前确定建筑物间安全距离的主要依据之一。该文提出了轰燃后火焰在室外一定距离处辐射热通量的计算方法；并在喷出火焰不受室外风影响的情况下，利用小规模试验的结果对这一方法进行了验证。     

基于可疑筛查技术研究有机磷阻燃剂V6转化规律

运用Orbitrap高分辨质谱仪,评估了人体肝微粒体(HLM)代谢V6的转化规律.除5种已被报道过的O-脱烷基、氧化性去磷酸化和氧化脱氯产物外,首次发现了6种新型产物.基于其MS/MS质谱图,该6种代谢产物被鉴定为醛基和羧基产物.其中,5种代谢物生成量随孵育时间呈线性增加趋势,具有累积性.此外,推导的代谢途径表明,脱烷基化和羟基化代谢物进一步转化为次级代谢物,即醛和羧基代谢物.     

A review of polybrominated diphenyl ethers and alternative brominated flame retardants in wildlife from China: Levels, trends, and bioaccumulation characteristics

Accelerated industrialization and urbanization, and unregulated disposal of waste of electric and electronic equipment (e-waste) in China have caused environmental pollution of brominated flame retardants (BFRs). This review summarized the levels, trends, and bioaccumulation characteristics of polybrominated diphenyl ethers (PBDEs) and other potential alternative BFRs including hexabromocyclododecanes (HBCDs), 1,2-bis(2,4,6-dibromophenoxy) ethane (BTBPE) and decabromodiphenylethane (DBDPE) in wildlife from China. PBDE levels in wildlife from China were generally higher than those from other parts in Asia, and were comparable to those from Europe but were lower than those from North America. However, wildlife from the e-waste recycling sites in South China and East China contained much higher PBDEs compared to other reports around the world, suggesting the heavy contamination of PBDEs in these regions. The alternative BFRs were also detected in wildlife, revealing that the animals are exposed to these chemicals, in addition to PBDEs. Temporal trends indicated by levels in marine mammals from South China suggested that PBDE levels increased from the beginning of 1990s to 2000s, but decreased from the middle of 2000s, followed by relatively steady levels. In contrast, HBCDs were found to be continuously increasing from 1997 to 2007, indicating the increasing usage of HBCDs in China in recent years. Compared to PBDE profiles found in other parts, aquatic species and birds from China contained relatively higher contributions of BDE-28 and 209, respectively, suggesting the possible different usage pattern of PBDEs. Future works including keeping monitoring at a reasonable scale and frequency to make sure levels near urban centers indicative of population do not increase are needed. Additionally, focus effort on e-waste recycling regions to look for impacts and to determine if regulation/controls are resulting in lower environmental contamination, and incorporation of sentinel species in monitoring efforts are recommended.     

木材在不同放置角度下火蔓延特性的实验研究

选用厚度为2 mm与3 mm的木材,研究了可碳化固体可燃物在静止氛围中不同角度下的火蔓延特性.研究表明,在不同角度范围内火蔓延经历着熄灭、稳定燃烧、加速燃烧以及快速燃烧等变化过程.对两种厚度的木材火蔓延行为对比分析发现,在自然对流条件下,两种厚度木材的火蔓延极限角度分别为-5°,5°.另外,研究了试样上下表面火焰参数与火蔓延速度之间的关系.在10°＜α＜60°范围内,火蔓延速度计算值与实验值能较好拟合.     

低压下聚乙烯绝缘层导线火蔓延熔融滴落实验分析

低压导线火蔓延的研究对于飞机和航天器的防火安全具有重要意义。针对镍铬合金线芯、聚乙烯(PE)绝缘层导线火蔓延过程中的熔融滴落现象,在低压舱内开展了不同气压、不同氧气浓度的大量实验研究,获得了导线熔融滴落频率、质量和火蔓延速度,以及不同氧浓度熔融滴落的上下限。结果表明:(1)在熔融滴落过程中,由于滴落会产生向上的动量,从而使火焰在滴落后发生突然的"跳动"现象,火焰高度先增加后降低;(2)滴落上限和滴落下限随着氧浓度的增加而降低,并且可以划分为3个不同的区域:火蔓延仅存区;滴落和火蔓延共存区;无滴落无火蔓延区。滴落上限和滴落下限下降曲线在50%氧浓度、5kPa压力发生会合,此后只有火蔓延而不存在滴落现象。(3)当压力降低时,由于线芯温度增加,线芯传导热量增加,导致绝缘层熔融速率加快,从而使得滴落频率增加,同时液滴的表面张力随着压力的降低而增加,使得低压下液滴的质量变大。     

管道截面对氢气/空气预混爆炸影响的实验研究

为研究管道截面对氢气/空气预混火焰形状与传播速度的影响,选用三个长度都为1m而截面尺寸不同的方形管道进行实验。实验结果表明,在截面为80mm×80mm的管道中,四种氢气浓度下预混火焰都发展形成了郁金香火焰。火焰传播速度呈现上升,下降,再上升的波动。在截面为100mm×100mm和150mm×150mm的管道中,只有在氢气浓度20%下形成郁金香火焰,并且传播速度也出现上述的波动。而在氢气浓度25%,30%,40%下,预混火焰都呈指尖形传至管口,未出现郁金香火焰,传播速度都是不断上升。三个管道对比中,截面为100mm×100mm的管道内火焰平均传播速度最快,且压力波第一峰值最大。     

油品运输罐车呼吸阀阻火器设计与应用

针对油品运输罐车呼吸阀难以防火、防爆的安全隐患 ,设计安装油品运输罐车呼吸阀阻火器 ,提高了油品罐车的防火、防爆性能     

载铁改性沸石粉体抑制甲烷/空气扩散火焰试验研究

为发展洁净高效新型粉体灭火介质,以沸石粉体为基体,采用盐酸活化和氯化铁溶液浸泡方法制备载铁改性沸石粉体灭火剂。采用X-射线衍射仪(XRD)、扫描电镜(SEM)和X-射线荧光光谱仪(XRF)等仪器对该粉体灭火剂的结构和形貌进行表征。通过小尺度的杯式燃烧器试验研究载铁沸石粉体对甲烷/空气扩散火焰的灭火效果,并和未改性沸石粉体进行对比。试验结果表明,载铁改性沸石粉体灭火剂的灭火效能明显高于未改性沸石粉体。改性沸石灭火效能提高,主要是由于所负载的铁离子在火焰中转化为活性铁原子,参与清除火焰自由基的催化反应。