Influence of fire source locations on the actuation of wet-type sprinklers in an office fire

An experiment is conducted on a full-scale model office and an actual sprinkler system to explore the influence of fire source locations on sprinkler actuation. The office space is a brick structure that measures 5.7 m in interior length, 4.7 m in width and 2.4 m in ceiling height, and equipped with a sprinkler system. The investigated fire source (100 kW LPG burner) locations include the room center, wall centers, room corner, and other locations at different distances from sprinklers. The results show that actuation of the sprinklers is affected by the fire source locations and the heat conduction properties of the glass temperature-sensing bulb. Average actuation time of all the tests is 102 s, around 40 s faster than if the fire source is located in the room center. For fire sources in corners, sprinklers are quickly activated at the experimental time 75 s, showing concentrated hot gas flow.     

Measuring modified glass bulb sprinkler thermal response in plunge and compartment fire experiments

Automatic fire sprinklers use a heat sensitive element such as a glass bulb or fusible link to respond to the heat from a fire. The response of commercial fire sprinkler glass bulbs has been extensively characterised in convection-dominated dry gas flows but in real fires there may be more factors that influence the heat transfer to the bulbs such as radiation from the fire or cooling from adjacent sprinkler sprays. The time of activation is the only indication of the thermal response of typical commercial fire sprinklers using glass bulbs to a fire, but direct temperature measurement using a modified proxy may provide a better understanding of how sprinklers respond in a complex environment. Modified glass bulbs have been created that allow a thermocouple to be inserted in the bulb for direct temperature measurement. In this paper, the thermal response of sprinklers with these modified bulbs has been observed in hot-air wind tunnel plunge experiments and full scale room fire experiments. At the time of activation the measured temperature of the modified sprinklers was found to be higher than the nominal activation temperature specification for the unmodified sprinklers. For the compartment fires, a thermal response model generally predicted longer sprinkler activation times based on ceiling jet temperature and velocity measurements than was observed experimentally.     

Influence of fire ignition locations on the actuation of smoke detectors and wet-type sprinklers in a furnished office

Experiments were conducted in a full-scale model office equipped with movable and fixed fire loads to explore the influence of ignition source (movable fire load(s)) conditions on smoke detector and sprinkler actuation. The interior plan dimension is 5.7 m × 4.7 m and the net ceiling height is 3.3 m. Both northeast and southeast wings have a 2.1 m × 0.9 m single door to be opened. Seven fire scenarios (seven different ignited fire load configurations) under natural ventilation were investigated experimentally. The results show that the amount of fire load at the initial stage in a room fire does not markedly affect smoke generation and does not significantly impact the actuation time of the smoke detectors. When the fire source is located near a corner, the plume corner effect greatly increases; smoke detectors and sprinklers can activate quickly and effectively actuate the fire suppression. When the fire source is located in the room's center, given the uncertainty regarding smoke detector and sprinkler actuation, it may not be possible to control the fire spread.     

Probabilistic simulation of fire endurance of a wooden beam

This paper presents a probabilistic simulation approach to assessment of the fire endurance of a wooden load-bearing beam in a fire. The approach introduces several novel modelling techniques developed by VTT, such as the probabilistic fire simulator which is an interface enabling to run fire simulation models in the Monte Carlo mode and the time-dependent event-tree method which enables to take into account the active fire safety measures such as detectors, first-aid fire fighting, sprinklers and fire brigade intervention. Also the simulation of the response to heat and the mechanical performance of the structure are carried out using the Monte Carlo technique. The charring rate of the wooden beam is calculated by a new model that includes explicitly the principal sources of uncertainties and variabilites. The results show explicitly the effectiveness of different fire safety measures in reducing the risk of structural failure.     

A numerical simulation method for analyzing the thermal improvement effect of super-hydrophilic photocatalyst-coated building surfaces with water film on the urban/built environment

As an application of the super-hydrophilicity of a photocatalyst (TiO₂) coating, buildings are cooled by sprinkling water on their external surfaces coated with TiO₂. This is a new cooling technology that was recently developed in Japan. In order to make better use of this cooling system, quantitative prediction and evaluation of the cooling effect on the urban/built environment is required during design. In an attempt to provide a computer-aided simulation tool for supporting the above-mentioned design, we introduce a thermal simulation tool that was developed previously by the authors’ group. The goal of the present study is to develop a numerical model by which to predict the temperature of a TiO₂-coated surface with a water film and integrate the calculation algorithm into the simulation tool. The availability of the proposed model was discussed in the present paper. Various urban districts in downtown Tokyo were selected for a discussion of the availability of the simulation tool in which the proposed model is integrated. Simulations were performed to quantify the thermal improvement effect of the cooling system in terms of surface temperature reduction, mean radiative temperature (MRT), heat island potential (HIP), indoor air temperature, and cooling load reduction.     

Experimental investigation and numerical simulation of a furnished office fire

Experiments were conducted in a full-scale model room equipped with both movable and fixed fire loads to explore fire growth and spread via heat release rates, indoor air temperature and species concentration. The room space is a brick structure that measures 5.7 m in interior length, 4.7 m in width and 2.4 m in ceiling height. The northeast and southeast corners each feature a 2.1 m × 0.9 m open doorway. Numerical simulations with parameter adaptation were carried out using FDS software to predict the fire features and were compared with the experimental results. In this study, the material properties and oxygen limit settings in the FDS software were tested to explore their influence on the tendency of heat release rate and on the total amount of heat release. The results show that the heat release rate from the FDS simulations is comparable to the full-scale experiment results during the fire growth period. Temperature profile near ceiling can be modeled well. In the full-involvement burning and decaying periods, the qualitative trends were identical, although the simulated value differed greatly from the experimental result.     

Analyzing the impact of in-rack sprinklers in a warehouse fire: A demonstration of the role optimization has in mitigating damage

This study presents a tool that illustrates the potential and role that optimization can have in fire protection design and performance. Specifically, the tool uses validated engineering correlations to simulate a warehouse fire, and evaluates whether it is controlled by modeling the placement and number of sprinklers – both in-rack and ceiling. Using initial model inputs that include storage configuration, commodity type, water supply, and sprinkler type, we allow a fire to ignite and simulate its growth behavior and corresponding effects on a nearby target array. For any initial set of input parameters, our tool demonstrates the minimum number and location of available in-rack sprinklers to control the flame spread. With reasonable run times, our work yields new insights into the design of sprinkler systems and, more broadly, the usefulness of optimization in fire protection design.     

The fire situation and progress in fire safety science and technology in China

Since the 1950s, the direct property damage due to fire has increased with the development of industrialization and urbanization in China. The number of fire casualties has come down significantly since the 1980s while fire incidents with high casualties has occurred occasionally. Research on fire safety science and technology and its application have advanced, encouraged by Government at all levels, the Fire Service Department of the Ministry of Public Security and all of society. In recent years, the fire situation in China has become relatively stable and an effective strength in fire research has been established, comprising the four Fire Research Institutes of the Ministry of Public Security, the State Key Laboratory of Fire Science, fire enterprises and other fire research institutes. Since the 1990s, research has been carried out on fire detection and alarm, fire suppression techniques, structural fire-resistance, fire prevention techniques, fire modeling, performance-based fire protection design, urban fire protection planning, fire-fighting and rescue, fire protection standardization, fire dynamics and the fundamentals of fire protection. In the next 5 years, research will be focused on the theory of fire dynamics; evaluation techniques for fire risk and fire and rescue services of urban areas; new techniques of fire suppression systems and equipment and their engineering application; modernization of fire department apparatus and equipment; techniques for evaluation and design of structural fire resistance; human behavior in fire; development of a fire database; fire protection engineering economics; and performance-based fire protection design.     

试析火灾痕迹在火灾事故调查中的应用

在进行火灾事故调查时,火灾痕迹是重要线索,火灾痕迹为调查人员提供了客观事实,帮助调查人员了解火灾事故起因.文章运用调查法、文献法等对火灾痕迹类型进行分析,并就火灾痕迹在火灾事故调查中的应用做具体探究,希望能为相关实践工作提供些许理论参考.     

浅析建筑室外消防用水保证措施

根据相关规范要求,本文从消防水源的确定、取水口（井）的设置方式、室外加压消火栓的设置方式和室外消火栓设置问题等出发,着重分析了建筑室外消防用水保证措施应注意的问题。     

Effect of temperature on thermal properties of spray applied fire resistive materials

Thermal properties of fire insulation namely thermal conductivity, specific heat, thermal strain and mass loss play a critical role in determining the effectiveness of these materials to improve fire resistance of steel structural members. These properties vary with temperature and are predominantly governed by moisture content and chemical constituents. This paper presents the effect of temperature on thermal properties of different types of spray applied fire resistive materials (SFRM). High temperature property tests were carried out on three types of commercially available SFRM to measure thermal conductivity, specific heat, mass loss and thermal strain in the range of 20–1000 °C. Data from these tests show that temperature has significant influence on thermal conductivity, thermal expansion and mass loss of fire insulation. The measured test data are utilized to develop thermal property relationships for fire insulation in terms of temperature. The proposed relations can be used as input data in thermo-mechanical analysis for evaluating fire resistance of steel structures.     

Using passive cooling strategies to improve thermal performance and reduce energy consumption of residential buildings in U.A.E. buildings

Passive design responds to local climate and site conditions in order to maximise the comfort and health of building users while minimising energy use. The key to designing a passive building is to take best advantage of the local climate. Passive cooling refers to any technologies or design features adopted to reduce the temperature of buildings without the need for power consumption. Consequently, the aim of this study is to test the usefulness of applying selected passive cooling strategies to improve thermal performance and to reduce energy consumption of residential buildings in hot arid climate settings, namely Dubai, United Arab Emirates. One case building was selected and eight passive cooling strategies were applied. Energy simulation software – namely IES – was used to assess the performance of the building. Solar shading performance was also assessed using Sun Cast Analysis, as a part of the IES software. Energy reduction was achieved due to both the harnessing of natural ventilation and the minimising of heat gain in line with applying good shading devices alongside the use of double glazing. Additionally, green roofing proved its potential by acting as an effective roof insulation. The study revealed several significant findings including that the total annual energy consumption of a residential building in Dubai may be reduced by up to 23.6% when a building uses passive cooling strategies.     

The strategies of fire prevention on residential fire in Taipei

Records from Taipei City Fire Department show that age and gender of the victims, housing type, the location of the fire, source of ignition, hour range and residential fire deaths are all related to how and why residential fires occurred in Taipei City. With aids of the prevention strategy on residential fire which includes safety precaution, arson prevention and reinforcement of rescue training and the employment of fire rescue decision-making system, we are able to build hierarchy of prevention strategy to reduce the probability of residential fires and injury and deaths.     

Field study on indoor thermal environment in an atrium in tropical climates

Solar penetration through the transparent envelope can severely deteriorate indoor thermal environment inside an atrium building particularly in tropical climates. This paper reports the application of two low-cost measures, namely high level internal solar blinds and water spray, to minimise overheating problems on the three levels inside the atrium of a guesthouse in Southern China, where summer is hot and humid. The blinds reduce direct solar penetration at the top of the atrium whilst the evaporative spray system cools down the glazed surfaces of the atrium envelope. A site test was undertaken over 10 consecutive days covering both overcast days and clear days in July 2004. Measurement of indoor thermal environmental parameters was conducted on three levels in the atrium and the recorded data represent the internal conditions: with and without internal blinds protection from solar, and with and without water spray. This study has shown that on hot and clear summer days, with water spray and without blinds the average air temperature difference from 1200 to 1800 h between both first floor and second floor, and second floor and external were 5.7 and 1.7 K, respectively; whilst with blinds and without water spray the average air temperature differences were 8.7 and 4.8 K, respectively.     

A small-world network model for the simulation of fire spread onboard naval vessels

This work is devoted to the development of a small-world network model to predict real-time fire spread onboard naval vessels. This model takes into account short-range and long-range connections between neighboring and remote network compartments. Fire ignition and flashover, as well as fire transmissions through the walls and ventilation ducts are simulated using time-dependent normal probability density functions. Mean durations of fire transmission through the walls and ducts are determined by a three-zone model and a one-dimensional CFD code, respectively. Specific experiments are conducted in a steel room, representative of a naval vessel compartment, in order to validate the zone model. Then a proof of concept is developed by applying the network model to a full-scale vessel mockup composed of 113 compartments on 7 decks. A statistical study is conducted to produce fire risk maps, classifying the vessel compartments according to their propensity to burn.     

Numerical simulation of the interaction between two fire fronts in grassland and shrubland

The objective of this paper was to evaluate the potential for fully physical fire models to simulate the interactions between two converging fire fronts (a head fire and a back fire), in conditions similar to those encountered during suppression fire operations. The simulations were carried out using two fully physical models: FIRESTAR, in two dimensions, and Wildland Fire Dynamics Simulator, in three dimensions. Each modelling approach numerically solves a set of balance equations (mass, momentum, energy, etc.) governing the behaviour of the coupled system formed by the vegetation and the surrounding atmosphere. Two fuel profiles were tested: homogeneous grassland similar to landscapes in Australia and a shrubland representative of Mediterranean landscape (garrigue). Results from the two-dimensional and three-dimensional simulations were used to investigate how the two fire fronts interact together and mutually modify, or not, their own behaviour before merging. The results of these simulations showed that the merging of two fire fronts can result in a quick increase in fire-line intensity or in flame height. We concluded that physics-based simulations do reproduce reasonable and expected head- and back-fire interactions, but more work is needed to further understand the accuracy of such predictions.     

Numerical simulation of bolted steel connections in fire using explicit dynamic analysis

Behaviour of steel connections in fire is a multi-dimensional problem involving parameters such as temperature, tying forces and large deformations. Investigation of this behaviour will remain one of the main subjects for fire engineering research in the coming years. Finite element simulation plays an important role in the study of connections because fire tests are expensive to perform. Unlike normal structural analyses, finite element simulation of bolted steel connections is a challenging task, as large numbers of contacts exist in the model. This leads to convergence difficulties in static solvers. This paper explores the use of an explicit dynamic solver to analyse bolted steel connections. By comparing the results with those from static analysis and tests, it is shown that the explicit dynamic solver, with proper control, gives satisfactory predictions of the responses of steel connections up to post-failure deformations.     

Experimental study of water hammer-induced forces and deformations in dry pipe fire protection systems

When designing a fire protection system, every effort should be taken to ensure its maximum operational safety. Therefore, correct identification of the dynamic load affecting the system during water hammer occurrence is essential to increase the operational reliability of such fire protection systems on their design stage. A test stand with a simple deluge system was designed for the experiments. The layout consisted of a distribution duct and one straight branch line (including three different diameter values) equipped with three fire nozzles. However, the main objective of this study is not to study the water hammer itself but, rather, to study the forces and displacements induced by the water hammer. The measurement results will be used to calibrate a mathematical model created using MATLAB software. The verified model will in turn enable numerical determination of the dynamic force values for larger systems. Furthermore, these force values will allow for pinpointing the critical sections, for which it is necessary to prevent displacements or transfer the acting forces to the building structure.