The Use of Positive Pressure Ventilation Fans During Firefighting Operations in Underground Stations: An Experimental Study

Positive pressure ventilation (PPV) fans are widely used by the fire service during firefighting operations in buildings. Fans are positioned to create a flow through the enclosure. This flow can remove the smoke after the fire or affect the direction of the smoke to support firefighting operations. In subway stations, it is less common to use PPV fans. Here, 106 full-scale tests with up to four fans have been performed in a training building that represents a subway station. The fans were used as extraction fans. The generated flow through the subway station has been measured. The critical velocity for a hypothetical tunnel (W × H: 3.17 × 4.15 m) attached to the subway station has been calculated as 2.37 m/s. Reaching the critical velocity has been used as criterion for ‘success’. All combinations with four fans exceed this velocity, supporting the idea that the fans could be used to facilitate a firefighting operation. The location of the fans was varied. Combinations with three fans on the platform and one at the top of the staircase performed better than combinations with two fans on the platform, one on the landing and one at the top of the staircase. There is an optimum value for the distance between the fans on the platform and the first step of the staircase. This value depends on the angle of inclination of the fans. The fans were not capable of creating a flow that exceeded the critical velocity in the station itself (L × W × H: 60 × 7.15 × 4.53 m). However, a velocity of 2.40 m/s corresponds to a flow rate that will limit the backlayering distance in the station to 15 m. This was only achieved by tests with four fans (three on the platform and one at the top of the staircase).     

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.     

Fire Safety Measures in Historic Buildings for University Use

The paper summarises the results of an investigation intended to develop guidelines for implementing fire safety measures in historic buildings converted to university use, and which can be utilised in making design decisions and assessing project feasibility. In particular, the paper focuses on the relationships between a building's historical type, the applicable regulatory and performance requirements, and the design solutions that can be adopted in a given situation. The examples of such solutions provided in the paper, which regard functional requirements as well as those for fire safety, accessibility and utilities systems, are drawn from an analysis of recent case studies of historic building conversion to university use, evaluating the design approaches which were adopted and possible alternatives. In addition, the paper presents a series of parametric appraisals of the typical costs incurred in construction and utilities installation, together with a discussion of the development and application of a risk analysis method which can be used to evaluate the overall performance of specific design solutions or construction situations.     

高层建筑正压送风条件下楼梯间内压力分布规律的实验研究

建筑物疏散楼梯间内最常采用的防烟方法是机械加压送风。为了有效防止烟气侵入,楼梯间的正压必须维持在一定的范围之内,因此对机械加压送风条件下楼梯间内压力分布规律的研究尤为重要。本文采用大尺寸实验的方法,研究了不同送风量、不同开门工况下高层建筑楼梯间内的压力分布规律。研究发现,当所有楼层楼梯间和前室的门全部关闭时,各楼层压力呈现不均匀分布现象,距风机最近端楼层压力最低,而距风机最远端楼层压力最高;当楼梯间内出现开门楼层时,开门瞬间压力迅速衰减,直至接近为零。     

Effects of Leakage in Simulations of Positive Pressure Ventilation

The fire service uses a number of tactics to reduce hazards for fire-fighters and civilians within a structure on fire. One offensive fire-fighting tactic that has potential for rapidly improving or degrading conditions within the structure is ventilating the structure. Positive pressure ventilation is a tactic in which a fan is used to push hot products of combustion out of a burning structure. While a recent body of work has been produced on the effects of positive pressure ventilation in a number of fire systems, there is still widespread uncertainty on how the tactic affects the fire environment. Computational tools will play an important role in exploring the impact of positive pressure ventilation in various fire scenarios. In many simulations of structure fires, the impact of leakage on the evolution of the fire is not addressed. We find in this study that ad hoc models of leakage have significant impact on the evolution of the fire. Several ad hoc leakage models are proposed and these are studied in terms of their impact of the fire. We show that one particular leakage geometry is able to best model leakage effects in a series of fire simulations that are compared to experiments. Simple, first-order analysis is used to understand how these leakage flows affect the predictions.     

贵州地区居住建筑通风冷却技术的模拟研究

以贵阳地区为例,采用Fluent软件对贵州省居住建筑外掠墙体通风冷却措施进行数值模拟,通过计算得出不同送风温度和送风速度下满足有效通风所需要的时间,从而分析外掠墙体通风措施的有效性及其节能效果。结果表明:相同冷却效果下,与使用空调所产生的能耗相比,贵阳地区采取该措施的节能率高达67.9%。     

无创双水平气道正压通气治疗重症支气管哮喘的研究

目的探讨无创双水平正压通气（NIPPV）对重症支气管哮喘患者的治疗价值。方法将40例重症支气管哮喘患者按随机数字表法分成2组。对照组（n=20）予以氧疗、常规药物治疗;试验组（n=20）在氧疗、常规药物治疗的基础上予以NIPPV支持,应用美国STAR330型无创呼吸机,经面罩或鼻罩无创通气,采用S/T（自主呼吸/时间切换）,压力支持（PSV）＋呼吸末正压（PEEP）。比较2组治疗前和治疗后1、3h,第4天的血气分析指标（pH、PaCO2、PaO2、SaO2）的变化,治疗前后的最高峰流速（PEF）的改变及2组住院时间。结果治疗后,试验组血气分析指标以及PEF值的改善均较对照组明显（P〈0.05）;试验组住院时间较对照组明显缩短（P〈0.05）。结论对重症支气管哮喘患者早期应用NIPPV是有效的,但还需要大样本及更多的观察指标来监测患者的病情变化;对无创通气1～3h后病情无好转并呈进行性加重的患者应尽早改用有创机械通气,以免耽误治疗时机。     

大型公共建筑消防安全技术研究

大型公共建筑物功能繁多、人流量大、火灾负荷大等情况,都对其消防安全技术提出了严峻考验。文章阐述了大型公共建筑消防安全设计的重要性、消防特点和关键环节,分析了公共建筑消防安全技术存在的主要问题,并提出了相应的解决对策。     

大型公共建筑消防安全技术研究

大型公共建筑物功能繁多、人流量大、火灾负荷大等情况,都对其消防安全技术提出了严峻考验。文章阐述了大型公共建筑消防安全设计的重要性、消防特点和关键环节,分析了公共建筑消防安全技术存在的主要问题,并提出了相应的解决对策。     

塔式高层建筑楼梯间设计探讨

分析了剪刀式楼梯间的特点 ,以及在塔式高层建筑设计中的应用 ,结合《规范》,提出塔式高层建筑中的住宅 ,宾馆 ,写字楼在采用剪刀式楼梯间时应有所区别 .     

建筑物火灾室温预测网络模型的算例验证与实验

论述了室温网络模型及其隐式差分方程,对烟流性状预测软件中的室温预测部分进行了算例验证与实验研究,结果表明：算例计算结果与日本同类软件的计算结果基本相同,软件的计算结果与实验结果吻合得很好,完全符合火灾时室温的发展与变化规律。     

古建筑消防保护技术探讨

中华民族有着辉煌灿烂的建筑文化遗产,但是保存至今的大量古代宫殿、坛庙等建筑文物存在很大的火灾隐患.为了对现存古建筑有针对性地、合理地进行消防保护,分析了古建筑火灾特征和火灾危险性以及现存古建筑的建筑特征,对现有古建筑消防保护措施的利弊进行了比较,在此基础上提出了古建筑性能化消防保护的构想和思路,并对古建筑性能化防火技术的可行性和适用性作了进一步的探讨.从而提出对现存古建筑进行消防保护时,可以采取现有保护措施与性能化保护技术相结合的方法,以达到更好的保护效果.     

对工程中火灾应急照明设计的探讨

从应急照明的现状及存在主要问题出发,介绍了应急照明的主要内容,重点阐述应急照明的系统设计,并对应急照明导线的选择及敷设、灯具布置及其控制进行了分析,设计中应结合实际选择合理的设计方案,以保证应急时系统可靠运行。     

严寒地区住宅建筑冬季通风研究

针对严寒地区节能住宅建筑冬季卫生通风不足的问题，本文应用Fluent软件对安装通风装置的示范住宅建筑的室外风场、室内气流组织及温度分布进行模拟研究并实测室内空气温度场。在严寒地区，为保证适当的卫生通风和气流组织，应加强热压的作用，而尽量避免风压的不利影响。对严寒地区典型的建筑住区不同尺度的外部风环境模拟分析结果表明：除建筑住区的迎风面建筑外，整个建筑住区及建筑子区内风场分布较为均匀，符合严寒地区冬季避免冷风侵入耗热量的建筑节能设计。为避免迎风面建筑较高层住宅的背风向房间出现进风口变为排风口的现象，需加强屋顶排风风口处的引风作用；示范性通风建筑室内的进风角度及安装位置、建筑构件、家具的材料以及家具摆放位置等是影响室内热舒适性和室内气流组织的主要原因。     

玻化微珠整体式保温隔热建筑结构耐火性研究

介绍了玻化微珠整体式保温隔热建筑的概念,根据火灾时室内的温度一时间关系和钢筋混凝土结构的热传导方程,借助有限元分析软件ANSYS,对火灾作用下钢筋混凝土楼板截面温度场进行了计算,获得楼板截面温度场分布规律,证明了玻化微珠整体式保温隔热建筑具有良好的耐火性能.     

Mechanical Ventilation in Office Buildings and the Sick Building Syndrome. An Experimental and Epidemiological Study

The effects of mechanical ventilation on the sick building syndrome (SBS) were studied in an office building with 2150 employees, where the mechanical ventilation and indoor air quality were commonly blamed for causing symptoms typical of the SBS (nasal, eye, and mucous membrane symptoms, lethargy, skin symptoms and headache). The mechanical ventilation rates in the building were high (mean 26 l/s/person). To test the hypothesis that mechanical ventilation causes the SBS, a controlled experimental study was carried out by shutting off the ventilation in one part of the building and reducing the ventilation rate by 75% and 60% in two areas while leaving one part unaltered as a control. The experimental reduction of the ventilation rate did not alleviate the symptoms. On the contrary, the reduction of the ventilation rate caused a slight but statistically significant relative increase in symptoms (p < 0.05). In the cross-sectional analysis of the baseline data the SBS symptoms did not associate significantly with the ventilation rate (range 7–70 l/s/person). In the linear regression model, a positive correlation was found between temperatures above 22°C and the occurrence of symptoms (p < 0.05). Subjects exposed to environmental tobacco smoke had more symptoms than those not exposed (p < 0.01). Women reported more symptoms than men (p < 0.001). In addition, any prior history of allergic diseases (p < 0.001) and a negative attitude towards the social atmosphere at work (p < 0.001) were significant determinants of the SBS.     

商业建筑的防火设计研究

商业建筑通常位于闹市区,不仅人流量大,而且人群集中,需要保证建筑物有足够的耐火能力。商业建筑通过防火墙、防火间隔墙、防火门窗、防火卷帘、防烟分区、防火间距、安全疏散通道出口等的合理设计,可以有效降低火灾事故的发生。本文将在对商业建筑防火设计要求分析的基础上,从多个角度探讨防火设计的具体方法。     

探究民用建筑消防设计

本文以消防自动报警系统设计、消防给排水设计、消防联动系统设计、消防设备过负荷保护为重点,探究民用建筑消防设计。实践证明,保障民用建筑消防设计质量,在提高建筑应用安全性,保障人们群众生命财产安全等方面发挥着重要现实意义。     

风口上置置换通风的实验研究

对风口上置置换通风系统进行实验研究,得出此种通风方式下送风口的速度分布,室内的温度分布,O.1m处的风速等实验数据.通过分析实验数据得出,风口上置置换通风在满足室内热舒适性的前提下,能够提高房间的负荷承担能力,与混合通风相比能够得出较高的通风效率;另外,阶梯形的风口较普通的送风口能较少的卷吸上区品质差的空气,能更好地满足上置置换通风的风口特性要求.