Design and Optimization of New Smoke Exhaust Pipe for Mining Trucks

In order to improve the maintenance efficiency,extend the use time,ensure that the exhaust emission meets the standard,forthe 830E truck heating bucket exhaust pipe design defects,the current single smoke exhaust system is transformed into atime period,convertible smoke exhaust system.After the transformation,it can not only realize the side row to prevent direct corrosion of the box bucket in summer,but also realize the heating of the box bucket at low temperature in winter to prevent snow and ice and frozen blocks from sticking to the box bucket and the materials transported.After the transformation can save a lot of manpower,material resources,financial resources,improve the service life.

Study of the Influence of the Distance between Smoke Outlets and Fire Source on Smoke Flow Characteristics in Tunnel Fires

This paper explores the smoke flow characteristics in tunnel fires,giving a particular emphasis on the effects of different distances between the smoke outlets and the fire source.It examines the smoke behavior under different conditions,including variations in heat release rates,exhaust volumetric flow rates,spacing between smoke outlets,and the longitudinal fire source positions.Results indicate that altering the fire source positions and the smoke outlets in the tunnel leads to variations in the properties of smoke flow both the fire source upstream and downstream;the distance between fire source and smoke outlet increases gradually,airflow rate decreases initially and eventually reaches a stable state.Similarly,smoke mass flow rate exhibits an increasing trend that eventually reaches a stable state.Moreover,the heat exchange between the tunnel walls and hot smoke increases as the smoke outlet moves further away from the fire source.This interaction leads to a reduction in the heat exhaust coefficient and a decrease in the distance the smoke spreads.This study investigates the impact of altering the relative longitudinal fire source positions and smoke outlet on smoke flow characteristics by numerical simulation.A theoretical analytical method is used to give a predictive model for the heat exhaust coefficient and the smoke spreading distance.This research can support the theory and technical process of tunnel smoke exhaust prevention and control.

Study on the Influence of Setting Parameters of Tunnel Centralized Smoke Extraction System on Fire Smoke Flow and Temperature Decay

The centralized smoke exhaust system of shield tunnel is an important determinant for tunnel fire safety,and the use of different design parameters of the tunnel smoke exhaust system will affect the smoke exhaust effect in the tunnel,and the influence of different design parameters on the smoke exhaust effect and temperature attenuation of the tunnel can help engineers in designing a more effective centralized smoke exhaust system for the tunnel.In this paper,the Fire Dynamic Simulator(FDS)is utilized to examine smoke exhaust vent settings for a centralized exhaust system in shield tunnel with both flat and sloped conditions,including slopes of+4.5%and−4.5%,under a 30MWfire power with a 150m^(3)/s smoke exhaust rate.The results suggest that maintaining a vent spacing of 60m and a vent size of 4.0 m×1.5 m is a reasonable configuration for centralized smoke exhaust systems in both flat and slope shield tunnels.This choice helpsminimize construction costs and prevent excessive smoke accumulation.It also promotes favorable conditions for maintaining temperature distribution at 2-m height,visibility,smoke spread distance,and temperature below the ceiling,all below the threshold values,while ensuring high smoke extraction efficiency.However,in the slope section,the chimney effect can disrupt exhaust efficiency,visibility,ceiling temperature,and temperature distribution at a height of 2 m.Employing different opening methods,such as having 2 vents up and 4 vents down in a+4.5%slope and 4 vents up and 2 vents down in a−4.5%slope,can help mitigate these effects.Furthermore,the temperature decay formula for shield tunnels follows a bi-exponential decay pattern,and different design parameters of centralized smoke exhaust systems have minimal effects on temperature decay in shield tunnels.

Design of Mechanical Smoke Exhaust System in Large Space of Convention Center

The volumetric flow rate of smoke generated from the fire in large space often reaches to hundreds of thousands CMH because of extended floor height and as it’s more difficult to isolate the smoke to the limited area, comparing to normal-scale building, design and operation of effective smoke control system for large space is more than important. In this study, with the analysis model for such a large space as exhibition hall or conference room in conventional center, design of mechanical smoke exhaust system was conducted based on currently-available design standard which was then followed by numerical analysis of the design using 3D numerical analysis method. For conference room at 2.0 MW heat release rate, 99,173 CMH flow rate is required, if smoke layer is maintained at 60% of the floor height and for exhibition hall at 8.8 MW with 80% of floor height, flow rate required is 219,802 CMH, which are incorporated into the design. In view of 3D numerical analysis, accuracy of the design according to algebraic expression is sufficient.

Study of Numerical Analysis on Smoke Exhaust Performance of Portable Smoke Exhaust Fan

In houses and general buildings of environment where smoke control equipment is not installed, or its operation is difficult, there is a need to develop and utilize a portable smoke exhaust fan that can perform emergency ventilation in case of fire suppression and rescue operations. As a part of the development process for portable smoke exhaust fans, a numerical analysis model of the portable smoke exhaust fan was derived from the building in which a fire occurred, and an analysis on the smoke and toxic gas exhaust effects was performed in this study. The numerical analysis results showed that under a condition where the height of an opening is less than 1.0 m after fire source disappears in a situation where the smoke exhaust fan does not operate, smoke does not come out well, and thus the density of smoke within the target area does not drop significantly. On the other hand, if the smoke exhaust fan operates after the fire source disappears, smoke is directly exhausted to the outside due to the operation of the smoke exhaust fan, and the smoke density within the space drops sharply in all opening height conditions, thereby getting close to zero.

Jingchu Brand Energy-saving Oil and Smoke Exhauster

The Beijing Jingchu Industry General Co. is a famous enterprise producing kitchen utensils and household electrical appliances. The Jingchu brand energysaving oil and smoke exhauster produced by the company is made of imported materials with overseas advanced technology for production and measurement. All indexes have reached the domestic advanced level. The exhauster is equipped with

隧道火灾相向射流排烟系统烟气质量流率比例系数

为探究隧道相向射流排烟系统中火灾发生时烟气的流动特性,通过FDS数值模拟研究隧道内不同上、下游风速工况下的上、下游烟气质量流率变化。基于等效风速、理论分析和数值模拟结果得到上、下游风速与烟气质量流率比例系数的关系式。结果表明:当等效风速小于临界风速时,上、下游烟气质量流率比值和烟气质量流率比例系数随等效风速增加而减小,并且等效风速与上、下游烟气质量流率比值存在线性关系;当等效风速大于临界风速时,上、下游烟气质量流率比值和烟气质量流率比例系数为0。

排烟口朝向与挡烟垂壁对地铁站台排烟效果的影响

为提高地铁站台的排烟效果,采用数值模拟方法,对地铁站不同排烟口朝向的机械排烟系统排烟效果进行分析,并进一步对比挡烟垂壁高度对排烟效果影响。研究结果表明:排烟口朝向不是影响烟气控制效果的主要因素,顶面排烟的排烟效果最佳,其总排热量是底面排烟的1.32倍,总排烟量是底面排烟的1.19倍;并通过分析3种排烟系统吸入烟气的方式和温度解释排烟效果产生差异的原因;增设挡烟垂壁可起到良好的控烟效果,当挡烟垂壁下沿高度分别降低至3.5,3.0,2.5 m时,顶面排烟,侧面排烟和底面排烟能够将烟气控制在起火防烟分区;挡烟垂壁与机械排烟系统具有协同作用,设置挡烟垂壁可以有效改善排烟效果,因此建议采用排烟管道顶面开口的排烟方式,并可通过设置一定高度的挡烟垂壁提高现有排烟系统的排烟效果。研究结果可为地铁站台排烟系统设计提供参考与借鉴。

某核电厂电气仪控房间火灾排烟温度分析

对某核电厂电气厂房的2个电气仪控房间进行了火灾排烟温度模拟分析。模拟计算了排烟系统不同时刻启动时,这2个防火空间室内空气温度的变化情况。结果表明:排烟系统启动后房间空气温度迅速降低,然后逐渐升高,最后随着火灾热释放速率的降低而逐渐降低;对于手动启动的排烟系统,需及时启动才能有效排除火灾中的烟气;需合理设置排烟防火阀,以保护排烟风机等。

烟草烟雾与机动车尾气暴露建立的大鼠慢性阻塞性肺疾病模型比较

目的对比烟草烟雾(CS)暴露和机动车尾气(MVE)暴露两种方法构建的大鼠慢性阻塞性肺疾病(COPD)模型的模拟程度。方法将24只雄性SD大鼠按随机数字表分为对照组、CS组与MVE组,每组8只。CS组与MVE组大鼠分别采用CS或MVE暴露建立COPD模型。建模结束后,检测各组大鼠的肺功能;收集大鼠支气管肺泡灌洗液(BALF),检测其中炎性细胞数、炎性因子白细胞介素(IL)-6和肿瘤坏死因子(TNF)-α及黏蛋白5AC(MUC5AC)含量;HE染色观察肺组织和气道病理变化;PAS染色检测气道杯状细胞增生情况。结果与对照组比较,CS组和MVE组大鼠的肺功能参数吸气阻力(RI)、肺总量(TLC)、肺静态顺应性(Cchord)均明显增高(P<0.05),而呼气流速参数FEV50/FVC明显降低(P<0.05);与MVE组相比,CS组大鼠的RI、TLC、Cchord均明显增高(P<0.05),FEV50/FVC降低(P<0.05)。肺组织HE染色结果显示,CS组和MVE组大鼠平均肺泡截距(MLI)均高于对照组(P<0.05),CS组MLI高于MVE组(P<0.05)。CS组和MVE组大鼠BALF中白细胞、中性粒细胞、巨噬细胞和淋巴细胞数,以及IL-6、TNF-α含量均高于对照组(P<0.05);且CS组中炎性细胞数、IL-6及TNF-α含量均高于MVE组(P<0.05)。肺组织PAS染色结果显示,CS组和MVE组大鼠大气道杯状细胞较对照组均明显增多(P<0.05),且CS组杯状细胞数高于MVE组(P<0.05);CS组和MVE组BALF中MUC5AC含量均高于对照组(P<0.05),且CS组大鼠BALF中MUC5AC含量高于MVE组(P<0.05)。结论应用CS或MVE暴露均可建立大鼠COPD模型,但CS暴露比MVE暴露能更好地模拟COPD急性加重期特征。

隧道单侧集中排烟模式下烟气蔓延距离研究

为研究隧道火灾单侧集中排烟模式的烟气流动特性,采用缩尺寸模型试验研究了隧道温度分布和烟气蔓延距离。定量分析不同火源热释放速率及排烟量作用下单侧集中排烟模式隧道纵向温度的变化规律,并通过温度场判断不同火灾工况下的烟气蔓延距离,探究火源热释放速率、排烟量与烟气蔓延距离的数学模型。结果表明:在隧道单侧集中排烟模式下,温度场呈非对称分布,排烟风机侧烟气蔓延距离大于封闭侧;火源上、下游的烟气蔓延距离随火源热释放速率的增大而增大,随排烟量的增大而减小;通过理论分析,得到单侧集中排烟模式下火源上、下游烟气蔓延距离的预测模型。

基于区段的地下空间环路通风排烟设计方法

为实现多匝道、多地块、内部空间复杂的地下空间环路烟气控制,提出一种区段式排烟方法:将地下空间环路与地块通过防火门分隔,形成独立的构筑物,结合隧道结构,确定风机房位置,划分区段,使烟气在一定区域内排出。以滨江地下环路为例,在隧道主线上均匀布置6个排烟风机房,并以此为节点,将隧道划分为8个区段。当火灾发生时,开启所在区段两端的风机进行排烟。由于各区段不设置固定分隔,整个风道是贯通的,因而各个风机房里的风机可互相作为备用排烟风机,以降低成本。采用数值模拟软件建立模型,对排烟口开启数量和间距进行模拟,确定排烟量为90 m^(3)/s、排烟口间距为30 m、开启8个排烟口的排烟方案。从人员疏散环境以及排烟效率对典型区段进行分析,结果表明:烟气控制在一定的范围内,人员疏散环境安全,排烟效率达到90%,证明方案合理可行。

直立式机械排烟临界排烟口高度

为改善地铁站台的排烟效果,提出了一种在排烟管道顶部上接风管的新型直立式机械排烟。通过数值模拟分析地铁站台火灾时采用直立式机械排烟的效果。结果表明:采用上接风管的直立式排烟相比于排烟管道顶面排烟具有明显优势,其排热量可增加14.51%;直立式排烟存在一个临界排烟口高度,当排烟口高度较低时无法排出顶棚下方的高温烟气,而当排烟口高度超过该临界高度后,受到顶棚的限制其排烟效果反而会下降;临界排烟口高度与排烟风速无关,但受排烟口边长的影响,且在临界高度时排烟口与顶棚间的距离近似等于排烟口边长的一半。

公铁合建双层盾构隧道设计关键技术

为解决公铁合建双层盾构隧道面临的总体布置、结构设计、汽车与地铁车辆联合振动以及通风排烟等技术难题,以武汉长江公铁隧道和济南黄河济泺路隧道工程实践为基础,采用方案综合比选、2.5维数值计算等方法,对公铁合建双层盾构隧道设计关键技术进行系统研究。结果表明:1)通过对隧道平面、纵断面和横断面的合理优化布置,并在废水泵房段、疏散楼梯段采取特殊布置方案,可减少公铁合建盾构隧道地下空间占用,并提高断面利用率,减小盾构隧道外径;2)采用半预制半现浇的管片+非封闭内衬结构型式,能充分发挥内部结构与管片衬砌的联合承载作用,显著减小河床冲淤作用;3)汽车与地铁联合振动作用对隧道影响较小,隧道基底饱和粉细砂地层不会发生液化;4)地铁隧道采用分段纵向烟道,可解决地铁长大区间无风井条件下的排烟难题,同时提高疏散便捷性,并大幅降低建设难度;5)公铁合建隧道在运营管理上不可避免地会出现交叉和影响,建议在管理界面划分和投资分劈上提前研究,便于决策。

环境压力对隧道竖井排烟影响的数值模拟研究

通过FDS数值模拟,研究环境压力对隧道火灾的烟气蔓延规律、烟气分层特性和竖井排烟效果的影响。研究表明:低压环境下隧道顶棚的烟气具有更高的温度,火源-竖井和竖井下游区域顶棚温度的纵向衰减曲线均符合指数分布,温度衰减系数随着环境压力的增加而减小;火源-竖井区域的烟气运动由热浮力主导,层化曲线变化趋势不明显,竖井下游区域层化曲线受环境压力的影响较大,随着环境压力的降低,层化曲线出现顺时针旋转的趋势,层化强度降低,烟气层稳定性下降;低压环境中竖井的排烟效果要优于常压状态下的竖井,且竖井底部产生吸穿现象的临界高度也有所增加。因此,与一般海拔地区相比,海拔较高地区的隧道发生火灾时,较高竖井的排烟效果更好,吸穿临界高度更高,对下游烟气层稳定性的影响更小,更利于疏散排烟。

侧部双点排烟模式排热效率研究

为探究隧道火灾侧部排烟口排热效率的表达公式,采用理论分析推导出排热效率与火灾热释放速率、排烟风速、排烟口距地面高度、排烟口间距4个影响参数的量纲一关系式,通过FDS数值模拟研究不同因素影响下的烟流特征并对数据进行拟合,确定了排热效率与这4个影响参数的关系。结果表明,在侧部双点排烟模式下,排热效率随火灾热释放速率增大呈-0.33次方减小关系,与排烟口排烟风速呈0.23次方增长关系,与排烟口距地面高度呈1.25次方增长关系,与排烟口间距呈-0.57次方减小关系,最终通过线性拟合建立了考虑吸穿影响的侧部双点排烟模式下排烟口处排热效率的模型。研究结果可为隧道侧部排烟系统的设计提供参考。

高海拔铁路隧道紧急救援站排烟结构尺寸参数及排烟效果

为明确高海拔铁路隧道紧急救援站排烟结构合理的尺寸参数,以某高海拔铁路特长隧道为工程依托,数值模拟并分析救援站联络排烟道数量、直径以及平行排烟道尺寸对排烟效率、站内温度和能见度的影响。结果表明:总体上距火源越近,排烟效率、拱顶及疏散站台温度越高,且火源前端能见度显著高于后端,但不同排烟结构参数下的具体分布规律差异显著;随着联络排烟道数量增加,救援站排烟效率略有增加,救援站后端拱顶温度显著降低,部分联络排烟道会出现烟气倒流,救援站疏散站台特征高度能见度低于10 m的范围显著增加;随着联络排烟道直径增加,救援站排烟效率及救援站两端拱顶温度均降低,救援站能见度显著下降;平行排烟道尺寸对救援站排烟效率及站内温度分布影响较小,但随着尺寸增加,救援站疏散站台特征高度能见度低于10 m的范围呈“先增后减”的变化趋势,紧急救援站内联络排烟道数量设置不宜过多,推荐联络排烟道直径为3 m,平行排烟道断面宽度为5 m。

地下立交互通匝道集中排烟效果研究

针对两端连接主隧道的互通匝道火灾烟气控制问题,依托南京建宁西路曲线A匝道工程,借助数值模拟软件FDS,研究HRR为30 MW下纵向诱导风速、排烟口尺寸及火源位置对顶部集中排烟效果的影响。结果表明:火源位于匝道中部,诱导风速为1.0 m/s时恰好保证烟气不发生“跨区蔓延”,诱导风速为1.5 m/s、排烟量为150 m^(3)/s时,控烟效果更好;匝道内烟气蔓延范围随排烟口尺寸增大而减小,当排烟口长宽比为4、面积为6 m^(2)时,匝道内烟气控制效果较好,系统整体排烟效率大于98%;排烟口长宽比不变时,拱顶最高温度随排烟口面积增大而降低;排烟口面积不变时,拱顶最高温度随排烟口长宽比增大而升高。火源位于匝道上游或下游时,排烟风量至少需增大至210 m^(3)/s,诱导风速需作针对性优化。

轨道交通地下单渡线配线区间烟控实测及模拟研究

为了明确单渡线配线区间不同排烟设计方案的烟气控制效果,选取某地铁线路的单渡线配线区间,通过现场实测和烟流数值模拟分析,得到影响隧道区间整体排烟能力和气流组织分配的因素。结果表明:单渡线形式下,隧道通风系统的排烟能力主要取决于TVF风机,在无射流风机且仅靠TVF风机的情况下,采用2送2排模式,能满足火灾区段断面风速的要求,且均未发生烟流通过渡线串线的现象;TVF开启台数对起火区间的风速提升显著,但采用4送4排模式会导致烟气过站。

特长跨海公路隧道联络烟道间距优化设置研究——以青岛第二海底隧道为例

青岛第二海底隧道通过在隧道的南北线排烟道上纵向间隔设置联络烟道,将南北线烟道联通。由于目前尚无公路隧道设置联络烟道的案例可供参照,为研究联络烟道对公路隧道防排烟效果的影响,亟需明确在不同联络烟道间距下隧道内火灾温度场、烟气蔓延情况、系统阻力等的分布规律,确定最优联络烟道间距。在现有评价指标烟气蔓延长度l_(60)、排烟效率η的基础上提出阻力削减率ξ,构建基于性能化的联络烟道间距优化评估模型;在调研全国各种隧道横通道间距设置配合形式后,采用Fluent软件模拟不同联络烟道间距下的烟流特性及数据。结果表明:1)联络烟道能有效降低排烟系统的阻力;2)随着联络烟道间距的缩短,烟气蔓延长度l_(60)由260 m缩小至180 m,排烟效率η由93.39%提升至97.80%,阻力削减率ξ由15.42%减小至2.20%;3)联络烟道间距为750 m和1500 m混合的设置方式能起到较好的排烟效果,此时继续缩短联络烟道间距对系统排烟能力提升有限。