Experimental Study of Fire Ventilation During Fire Fighting Operations

Fire ventilation measures taken by fire & rescue services, including positive pressure ventilation, were investigated. Fifteen tests were performed in a three-room apartment, with an attached staircase, on the first floor of a training facility. The fire source was a 0.5 m diameter pool of heptane. The temperature and pressure in the apartment, the weight of the fire source, and the flow through openings were recorded continuously. The tests showed that the rate of burning was increased by positive pressure ventilation. Also, positive pressure ventilation increases the temperature in rooms on the leeward side of the fire and reduces temperatures in rooms on the windward side of the fire. Safety and working conditions for fire fighters are improved by positive pressure ventilation, but it jeopardises the lives of anyone that might be trapped. The importance of command and control during fire fighting operations is prominent.     

火灾时隧道内温度场的模拟研究

根据传热学理论 ,建立隧道火灾后温度场计算公式 ,对隧道火灾后温度场随时间和空间的变化规律进行了研究 ,并研究了其影响因素     

Experimental Study of the Fire Behaviour on Flat Roof Constructions with Multiple Photovoltaic (PV) Panels

Fire experiments were conducted on four mock-up roof constructions with an array of six photovoltaic (PV) panels to study the fire dynamics and flame spread behaviour, so as to better characterise the fire risks of such a system. As it is customary to retrofit PV panels to existing warehouse roofs, where expanded polystyrene (EPS) and polyvinylchloride-based roofing membrane B_ROOF(t2) is a typical roofing, the experiments were carried out on such installations, but with a mitigation solution on top; 30 mm mineral wool or 40 mm polyisocyanurate (PIR). All mock-ups were 6.0 m long, whereas the width was 2.4 m (Experiments 1 and 2) and 4.8 m (Experiments 3 and 4), respectively. A wood crib was placed under the PV panels and it ignited the roofing membrane after 7 min to 8 min, which in all four experiments resulted in fire spread under all the six PV panels covering an area of 5.1 m?×?2.0 m. However, no self-sustained fire was observed beyond the area below the PV array. Within the first hour, the maximum temperatures were measured to respectively 175 °C and 243 °C underneath the two mitigation solutions of PIR insulation and mineral wool, which is more than 100 °C below the piloted ignition temperature for the EPS insulation. However, the EPS was ignited in both experiments with the PIR insulation due to thermal degradation of the protective material after approximately 1 h. These experiments confirm that a small initial fire underneath a PV installation can transform into a hazardous scenario due to the changed fire dynamics associated with adding the PV panels to the existing roof.     

钢结构节点火灾下的升温试验研究与理论分析

主要研究钢结构节点在火灾下的升温情况及有限元温度分析,利用自行设计和制作的试验炉,对钢结构节点的升温过程进行了试验研究,得出了火灾下钢结构的升温曲线,给出了计算节点升温的经验公式,并对火灾下的钢结构节点的温度进行了理论分析,理论分析结果和试验结果比较吻合.说明了理论分析的可行性和可靠性,进而论述了火灾下钢结构升温的一般规律,为节点的抗火设计和防火涂料的设计提供理论依据.     

Experimental Study on Fire Plume Characteristics in a Subway Carriage with Doors

Fire Technology - The widespread use of subway system provides convenience for the fast transportation in the cities, but the subway fire accident has the risk of causing serious consequence....     

Experimental Study of the Fire Dynamics in a Semi-enclosure Formed by Photovoltaic (PV) Installations on Flat Roof Constructions

Fire Technology - Flame spread experiments upon a BROOF(t4) compliant flat roof mock-up located below a vertical barrier were carried out for variations in gap height, inclination, subjacent...     

室内火灾烟气流动随机性研究述评

评述了目前国内外室内火灾烟气流动随机性研究的现状、室内空间火灾烟气流动随机性的基本原因、影响烟气流动随机性的因素以及这些因素的影响机理等.     

秦岭特长公路隧道火灾温度场分布试验研究

特长公路隧道火灾 ,扑救困难 ,易造成严重损失 ,是影响隧道安全运营的一个关键因素。借助火灾模型试验 ,以火灾规模和通风风速作为两个主要的影响因素 ,研究了火灾时隧道内温度场的纵向及横向分布规律 ,以及火灾时温度场的扩散范围。并根据试验成果对秦岭隧道结构的防火措施、设备的布置方案、火灾时通风风速的设定以及行车距离的限制等给出了合理的建议     

燃气热风发生器热风温度控制性能实验研究

针对热风发生器热风温度控制精度不足的问题,介绍了一种新型的全预混燃烧系统的热风发生器。通过实验研究了PID控制模式下热风温度的控制性能,并与传统的ON-OFF控制模式进行了对比研究,得出PID控制模式下温控精度达到±2℃,而ON-OFF模式下的温度波动范围为±20℃。结果表明PID控制模式应用到全预混燃烧系统的热风发生...     

火灾下钢-混组合楼板截面温度场的试验研究

对标准火灾升温条件下采用YX76-344-688型钢承板的组合楼板截面温度场的分布规律进行了试验研究,并提出了对截面温度场进行计算模拟的改进的有限差分方法。研究结果表明,混凝土内的水分对低温区混凝土的升温过程产生很大影响,而改进后的有限差分计算方法可以合理地考虑水分的影响,很好地模拟组合楼板截面在低温区和高温区的温度场分布。最后,提出了在不同升温方式下截面温度场的实用分析方法,可供工程防火设计时使用。     

Effects of PPV Attack on Thermal Conditions in a Compartment Downstream of a Fire

There have been relatively few technical studies conducted on the effects of PPV on compartments downstream of the fire. Live fire tests in an acquired house were conducted in order to study the effect of PPV attack on the thermal environment downwind of the fire. Temperature measurements were made using 40 thermocouples located in a fire room, hallway, and downstream room referred to as “the victim room”. Video camera and infrared camera images were taken in several locations to visually record the progress of the fire and firefighting. A total of eleven cases are reported in this study. These cases correspond to three different fan configurations: no fan, a 45.7 cm (18″) diameter fan with a volumetric output of 3.06 m³/s (6,500 CFM), and a 61 cm (24″) diameter fan with a volumetric output of 4.31 m³/s (9,130 CFM). Two venting strategies were used: venting the fire room and venting the victim room. Fluctuations in environmental factors such as wind and the inherent statistical variation common in fire testing made it difficult to draw many absolute conclusions. In general, however, we found that cases with fire room venting and fan application had somewhat higher fire room or hallway temperatures when compared to cases without fan application. We also found that cases with victim room venting and fan application resulted in higher gas temperatures in the victim room at the higher elevations than both fire room vented cases and cases without fan application.     

风井出口废气扩散的模拟及控制研究

为了解自风井出口排放出的污染物的浓度分布以及对其周围空气形成的污染范围,采用三维数值模拟的方法,对风井出口废气的对流扩散特征进行了模拟和分析,揭示了在不同外界风速和风向的条件下,出口处废气的扩散特征.计算结果表明,外界风速越高,废气扩散得越快;但因浓度衰减得也越快,故其能对大气形成污染的扩散范围加大到一定程度时又有减小的趋势;出口污染物会对距风井近距离范围内的大气产生一定程度的污染,可适当加高风井高度以使周围建筑物及人员免受污染物的危害.     

分户水平双管供热系统分室温控时的水力工况研究

本文分析了适用于分户热计量的分户水平双管同程式供热系统分室温控时的水力工况变化规律.应用基尔霍夫第一和第二定律建立了系统水力工况模型,考虑双管系统的重力循环作用力,联立多方程得出了用户调节室温时系统水力的变化规律.研究结果表明:对于分户水平双管同程式系统,非调房间受调低室温房间的影响而关小温控阀,且距离调节用户越远所受影响越小;对某立管上的用户调低室温,其立管上的定压差调节阀将关小以维持系统水力平衡.     

Experimental Study on Seismic Behavior of Roof Joint

International Journal of Steel Structures - Experimental study was conducted to investigate the seismic behavior of roof joint. Eight full-scale specimens were tested considering the effects of...