Article

SFPE handbook of fire protection engineering

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Abstract

Sumario: Hydraulics -- Introduction to mechanics of fluids -- Conduction of heat in solids -- Convection heat transfer -- Radiation heat transfer -- Fire plumes -- Natural convection wall flows -- Vent flows -- Ceiling jet flows -- Thermochemistry -- Chemical equilibrium -- Thermal decomposition of polymers -- Generation of heat and chemical compounds in fires -- Toxicity assessment of combustion products -- Movement of people -- Behavioral response to fire and smoke -- Flammability limits of premixed and diffusion flames -- Flame height -- Air entrainment into buoyant jet flames and pool fires -- Ignition of liquid fuels -- Flaming ignition of solid fuels -- Self-heating and spontaneous combustion -- Smoldering combustion -- Surface flame spread -- Smoke production and properties -- Properties of building materials -- Structural mechanics -- Burning rates -- Estimating temperatures in compartment fires -- Smoke and heat venting -- Fire hazard calculations for large open hydrocarbon fires -- Explosion protection -- Emergency movement -- Compartment fire-generated environment and smoke filling -- Design of detection systems -- Automatic sprinkler systems calculations -- Foam system calculations -- Fire temperature-time relations -- Analytical methids for determining fire resistance of steel members -- Analytical methods for determining fire resistance of concrete members -- Analytical methods for determining fire resistance of timber members -- Smoke control -- Applications of fire risk analysis -- Probability concepts -- Statistics -- Extreme value theory -- Reliability -- Probability models in fire protection engineering -- Engineering economics -- Utility theory -- Value of human life -- Computer simulation for fire protection engineering -- Fire risk assessment schedules

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... The combustion parameters of n-butane and the properties of liquid n-butane that were used in the study are summarized in table 1. The values presented here are as obtained from the SFPE handbook (DiNenno, 2008) and other associated literature. The parameters that were varied in the study include: (1) Upon varying the aforementioned parameters, all other settings such as Q"=3565 kW/m 2 , H=10 m, dv50=500 μm, ew=1 (m 2 s/kg), vwind=0 m/s were strictly maintained constant. ...
... Ideally, we can say that decreasing the mesh cell extent by an element of two can decrease the discretisation miscalculation by an element of four. However, it can raise the computational interval by an element of sixteen(DiNenno, 2008;Harada et al., 2016;Project Manager H Salley RP Kassawara, 2007). In the grid sensitivity study done by us, the D * /dx values fluctuated between four to sixteen (4 for Coarse mesh and 16 for refined mesh). ...
... In the grid sensitivity study done by us, the D * /dx values fluctuated between four to sixteen (4 for Coarse mesh and 16 for refined mesh). These standards were utilized for sufficiently resolving the plume dynamics alongside other mathematical attributes of the models also(DiNenno, 2008;Harada et al., 2016;Project Manager H Salley RP Kassawara, 2007). ...
Article
Accidental fires result in extensive loss of property, damage to the environment and a large number of fatalities every year. When fuel collects in the form of a pool and burns, it is termed a pool fire. Pool fires may burn in isolation – Non-interacting or as Single Pool Fires (SPFs) – or flames from multiple pool fires may interact with each other and burn in what is termed as Multiple Pool Fires (MPFs). Even as single pool fires (SPFs) are difficult to control, interacting flames due to multiple pool fires (MPFs) are even more difficult to extinguish. Compared to SPF, MPFs tend to have much higher flames and are reported to have extraordinary thermal intensity. Accidental pool fires in warehouses, commercial and residential buildings may interact, giving rise to interacting pool fires (MPFs). The commonly used technique to suppress fires in enclosures such as warehouse, commercial or residential buildings is to use sprinklers. Hence, this study reports the numerical simulations performed to analyse the effectiveness of water-mist sprinklers in extinguishing MPFs. The related CFD coding and simulations were performed using Fire Dynamics Simulator (FDS), FDS tools like Pyrosim (pre-processor) and Smokeview (post-processor) packages. The effect of the ratio of the separation distance between the pools (S) to the diameter (D) on the overall fire suppression efficiency of the water-mist sprinkler as a function of the water mist flow rate, the height of the ceiling, and sprinkler particle size are vigorously analysed in this work. The analysis presented in this article will mainly help to resolve problems associated with the effectiveness of mist-sprinkler in warehouse fires regarding process safety viewpoint.
... Li-ion batteries can release toxic substances, among those are carbon monoxide (CO), carbon dioxdide (CO 2 ) and other trace species. These gases can be fatal if inhaled in large quantities, primarily a concern to spacecraft crew as these may be asphyxiant or can cause anoxia [2]. During a thermal runaway event, Li-ion batteries can release the fluorine content of the electrolyte and other materials in the battery, such as the polyvinylidene fluoride (PVdF) binder and phosphoryl fluoride (POF3) from the electrodes. ...
... In addition, other gases may form such as hydrogen fluoride (HF), and hydrogen cyanide (HCN) [2]. The total amount of these toxic gases vary considerably depending on manufacturers, state of charge, battery type and chemistry. ...
... The second outburst had a diameter of 0.7 m. The outburst are described in Dinenno et al., as a thermal or "fireball" [2,10], which occur from a sudden release of a finite volume of gaseous fuel that is ignited. Flame width for the Surface Pro is not shown in the paper. ...
Conference Paper
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An accidental fire involving the Lithium-Ion (Li-ion) battery in a laptop computer is one of the most likely fire scenarios on-board a spacecraft. These fires can occur from a defect in the battery that worsens with time, overcharging the battery and leading to failure or accidental damage caused by thermal runaway. While this is a relatively likely fire scenario, very little is known about the how a laptop computer fire would impact a sealed spacecraft. The heat release would likely cause a pressure rise, possibly exceeding the pressure limit of the vehicle and causing a relief valve to open. The combustion products from the fire could pose a short-term and long-term health hazard to the crew and the fire itself could cause injury to the crew and damage to the spacecraft. Despite the hazard posed by a laptop fire, there is little quantitative data on the fire size, heat release and toxic product formation. This paper presents the results of initial attempts to quantify the fire resulting from a failed laptop battery tested at the NASA White Sands Test Facility (WSTF). The fire size and characteristics such as maximum heat release rate, total heat release, maximum temperatures and fire duration are determined. Using existing models and correlations for fires, the measured fire characteristics are extrapolated to laptop fires on a vehicle the approximate size of the Orion spacecraft.
... Dimension of pedestrian facilities is relevant in respect of comfort and safety in buildings with a large number of occupants (or people). Concerning comfort as well as safety several planning guidelines and text books are available [1,2,3,4,5,6,7,8]. In all these books or guidelines one basic characteristic to describe the dynamics of pedestrians is the relation between density and flow or density and speed, which following the terminology of vehicular traffic is also named the fundamental diagram. ...
... For different facilities like stairs and corridors the shape of the diagrams differ, but in general it is assumed that the fundamental diagrams for the same type of facilities but different widths merge into one diagram for the specific flow J s = J w . [1], PM: Planning for foot traffic flow in buildings [6] and WM the guideline 'Transporttechnik der Fussgänger' [4]. Figure 1 shows various fundamental diagrams used in planing guidelines [6,4,5]. ...
Preprint
The relation between speed and density is connected with every self-organization phenomenon of pedestrian dynamics and offers the opportunity to analyze them quantitatively. But even for the simplest systems, like pedestrian streams in corridors, this fundamental relation isn't completely understood. Specifications of this characteristic in guidelines and text books differ considerably reflecting the contradictory database and the controversial discussion documented in the literature. In this contribution it is studied whether cultural influences and length of the corridor can be the causes for these deviations. To reduce as much as possible unintentioned effects, a system is chosen with reduced degrees of freedom and thus the most simple system, namely the movement of pedestrians along a line under closed boundary conditions. It is found that the speed of Indian test persons is less dependent on density than the speed of German test persons. Surprisingly the more unordered behaviour of the Indians is more effective than the ordered behaviour of the Germans. Without any statistical measure one cannot conclude about whether there are differences or not. By hypothesis test it is found quantitatively that these differences exist, suggesting cultural differences in the fundamental diagram of pedestrians.
... A total of five fuel types, which include ethanol, kerosene, polystyrene foams, polyurethane foams and wood, were used, and the location of fire sources were divided into 12 compartments, as indicated by the numbers in circles, as shown in Figure 3. The values presented in the Society of Fire Protection Engineers (SFPE) handbook [17] were used as the material properties of fuels, as shown in Table 1. The combustibles were assumed to be chairs, tables, and sofas, which are mainly placed on the floor in the multiplex building, and the heat release rate (HRR) of each combustible was set by referring to the DB provided by the National Center for Forensic Science (NCFS) [18]. ...
... In the fire simulation conducted in this study, the burning area was set as 1 m × 1 m, and the fire growth rate was assumed to be of a medium level with reference to the Structural Design for Fire Safety [20]. In general, factors that directly influence the safety of the occupants in the event of a fire include toxic gases, heat, and visibility [17], and the National Fire Protection Association (NFPA) presents tenability criteria, as shown in Table 2. In this study, a simulation was conducted on fire scenarios for a total of 60 cases, as shown in Table 3, and the temperature, visibility, and concentrations of oxygen (O2), carbon dioxide (CO2), and carbon monoxide (CO) at the fire compartment and nonfire compartment were measured for each scenario with the use of measurement devices placed in a total of 27 locations at intervals of 1 m, as shown in Figure 5. ...
Article
Full-text available
When fire occurs in a large multiplex building, the direction of smoke and flames is often similar to that of the evacuation of building occupants. This causes evacuation bottlenecks in a specific compartment, especially when the occupant density is very high, which unfortunately often leads to many fatalities and injuries. Thus, the development of an egress model that can ensure the safe evacuation of occupants is required to minimize the number of casualties. In this study, the correlations between fire temperature with visibility and toxic gas concentration were investigated through a fire simulation on a multiplex building, from which databases for training of artificial neural networks (ANN) were created. Based on this, an ANN model that can predict the available safe egress time was developed, and it estimated the available safe egress time (ASET) very accurately. In addition, an egress model that can guide rapid and safe evacuation routes for occupants was proposed, and the rationality of the proposed model was verified in detail through an application example. The proposed model provided the optimal evacuation route with the longest margin of safety in consideration of both ASET and the movement time of occupants under fire.
... Empirical and experimental correlations have been deduced in the literature to estimate the height of turbulent flame in an open pool; Thomas [9] established set of equations to determine flame height disregarding and considering wind effect, he validated the equations experimentally using wooden strips as fuel, the paper generalized the equations for different types of fuel sources, however, researches proved that these equations are underestimating flame height for different types of fuels [3]. Heskestad [10] compared the different equations suggested by [8] and [9], and other different correlations against experimental work and deduced that the equation suggested by [11] is the most accurate to represent hydrocarbon fuel burnt in an open pool turbulent flame. Therefore, the equation developed by [11] is adopted in this paper. ...
... While tanks dimensions and distances between centers are clarifies in Tables I and II respectively. The fuel stored is Gasoline fuel, Gasoline fuel properties are summarized in table III, [3] and [10]. The atmospheric conditions are assumed to be the standard conditions; T a = 25[C], and RH = 50% which are representative to the average climate conditions at the tanks location. ...
... CO and smoke production result from incomplete combustion. The quantity of gas produced tends to vary over the course of a fire, with the CO yield usually increasing in the later stages of the combustion process when the material is extensively carbonized [111,116]. A linear correlation exists between the CO level and the heat release rate which suggests that health hazards associated with CO can be minimized by designing materials with low heat release properties [111]. ...
... The temperature during smoldering is typically 600-1100 K, while for gas phase, the flame temperature is within the range of 1200-1700 K. During the smoldering process, sufficient heat is produced to induce the formation of char [157], and the heat of combustion, around 16 kJ ·g −1 [158], is very low compared with PP at 43 kJ·g −1 [116]. The acetylation of cellulose, where hydroxyl groups are replaced by acetyl groups, creates cellulose acetate which has hydrophilicity and was shown to have higher thermal stability [159][160][161]. ...
Thesis
The urgency to develop and commercialize multi-component materials containing bio-based material is growing. Such materials can reduce the widespread dependence on petroleum and at the same time can reduce pollution while contributing to the economy. The demand for polymeric materials in applications such as automotive components, building materials, and the aerospace industry is increasing; however, one of the main drawbacks to use polymeric materials is their limited fire resistance. The objective of this work was to develop polypropylene plasticized cellulose acetate materials and to explore the use of magnesium hydroxide to enhance the flame retardant properties of these materials. Specifically, the thermal stability, flammability, crystallization, and mechanical properties were investigated. Material fabrication was accomplished using a two-step extrusion process. In the first step, cellulose acetate was plasticized with 30% triethyl citrate. The effects and viability of triethyl citrate as a plasticizer for the cellulose acetate were investigated by using differential scanning calorimetry, X-ray diffraction, and thermogravimetric analysis. Based on differential scanning calorimetry, the glass transition and the melting temperature were lowered by 39 °C and 77 °C, respectively. The effects of triethyl citrate on the degree of crystallinity of cellulose acetate was examined by X-ray diffraction. The degree of crystallinity of plasticized cellulose acetate was lower than that of cellulose acetate. According to thermogravimetric analysis, triethyl citrate lowered the thermal stability of the cellulose acetate by shifting the onset temperature of degradation and the temperature of maximum weight loss to lower temperature. According to the aforementioned analysis, cellulose acetate and cellulose acetate plasticized with triethyl citrate is applicable to be blended with polypropylene. Formulation of the polypropylene materials was investigated according to the thermal analysis by the thermogravimetric analysis. Choosing the level of each component in the fabrication was developed sequentially, polypropylene-grafted-maleic anhydride, plasticized cellulose acetate, and magnesium hydroxide. Different levels of polypropylene-grafted- maleic anhydride (1, 2, 3 wt.%), plasticized cellulose acetate (20, 30, and 40 wt.%), and magnesium hydroxide (10, 20, 30 wt.%) were used in order to choose the optimum level of each component. Based on the thermal analysis and activation energy estimation, the highest level of each component was chosen to fabricate the multi-component material. The results of scanning electron microscopy imaging showed that plasticized cellulose acetate had better compatibility with polypropylene matrix. The addition of plasticized cellulose acetate was affected negatively by the addition of magnesium hydroxide. Elemental mapping was carried out by energy dispersive X-ray spectroscopy attached to the scanning electron microscope. The results show good dispersion of plasticized cellulose acetate and magnesium hydroxide. After choosing the level of each component, which was 3 wt.% , 40 wt.% and 30 wt.% for polypropylene-grafted-maleic-anhydride, plasticized cellulose acetate, and magnesium hydroxide, respectively, the extruded materials were produced and cut into pellets. Injection molding and hot press compression molding were used to prepare the samples for characterization. Various characterization techniques were used to evaluate the inclusion of plasticized cellulose acetate and magnesium hydroxide in the polypropylene matrix. Thermal stability and kinetic studies were investigated by using thermogravimetric analysis (TGA) under non-isothermal conditions. The thermal stability of the polypropylene materials was evaluated through their TGA and DTGA curves at four heating rates (5, 10, 20, and 30 °C/min ). The results revealed that polypropylene materials with presence of plasticized cellulose acetate and magnesium hydroxide had good thermal stability where the thermal decomposition took place over a wide range of temperature and the maximum weight loss temperature was shifted to higher temperature. The Kissinger, Kissinger-Akhira-Sunose (KAS), and numerical integration methods were employed to estimate the activation energy. The activation energy of polypropylene materials with presence of plasticized cellulose acetate and magnesium hydroxide was higher than those of other polypropylene materials. Flammability and combustion behavior were examined through vertical burning, oxygen index, cone calorimeter and adiabatic bomb calorimeter tests. The results show that polypropylene with plasticized cellulose acetate and magnesium hydroxide ranked as V-0 according to the vertical burning test. The limiting oxygen index of polypropylene containing plasticized cellulose acetate and magnesium hydroxide was higher than that of polypropylene by 29%. According to the cone calorimeter test, the peak heat release rate and total heat release when the plasticized cellulose acetate and magnesium hydroxide were present in the polypropylene matrix were lower than that of polypropylene by 80% and 30%, respectively. The carbon monoxide and carbon dioxide yields revealed that polypropylene materials with plasticized cellulose acetate and magnesium hydroxide were significantly lower than that of polypropylene. The effective heat of combustion, estimated from the cone calorimeter and the heat of combustion from adiabatic bomb calorimeter, confirmed that the polypropylene material with plasticized cellulose acetate and magnesium hydroxide was less exothermic due to the reduction in the estimated heat of combustion. According to the stoichiometry of the carbon in the fuel and combustion products, the polypropylene material with higher yield of residue in the form of soot and char showed better flame retardancy than material with lower yield of residue. The results showed that polypropylene containing plasticized cellulose acetate and magnesium hydroxide had a higher yield of residue. Non-isothermal crystallization and nucleation morphology of the polypropylene materials was investigated by differential scanning calorimetry (DSC) and polarized optical microscopy. DSC thermograms showed that the crystallization temperature of polypropylene materials shifted to lower temperature with presence of polypropylene-grafted-maleic anhydride, plasticized cellulose acetate, and magnesium hydroxide. Development of the relative crystallinity was determined at four cooling rates. Avrami model was employed to analyze the data obtained from the DSC. Polarized optical microscopy was used to show the nucleation and crystal growth of the pure polypropylene and polypropylene plasticized cellulose acetate materials. Nucleation activity was estimated for the polypropylene materials. The results demonstrated that polypropylene-grafted-maleic anhydride, plasticized cellulose acetate, and magnesium hydroxide modified the nucleation and the crystal growth of the polypropylene materials. The mechanical properties of the polypropylene materials showed a marginal reduction in tensile strength and the elongation at break due to the inclusion of the plasticized cellulose acetate and magnesium hydroxide. The reduction was 13% and 30% due to the addition of plasticized cellulose acetate and magnesium hydroxide, respectively. However, the addition of plasticized cellulose acetate and magnesium hydroxide increased the Young’s modulus of the polypropylene materials. According to the impact test, there was a reduction in the impact strength of the polypropylene materials due to the addition of plasticized cellulose acetate and magnesium hydroxide. The impact strength reduced by 35% and 80% due to the addition of plasticized cellulose acetate and magnesium hydroxide, respectively. Differential scanning calorimetry and X-ray diffraction were used to study the effect of plasticized cellulose acetate and magnesium hydroxide on the degree of crystallinity and the crystal forms of the polypropylene materials. The addition of plasticized cellulose acetate reduced the degree of crystallinity of the polypropylene. On the other hand, plasticized cellulose acetate induced the ß crystal form, positively influencing the thermal and mechanical properties. The addition of cellulose acetate and magnesium hydroxide increased the degree of crystallinity. The most significant finding to emerge from this study is the feasibility of obtaining materials from polypropylene, plasticized cellulose acetate and magnesium hydroxide. The results of this study indicate that the materials have improved thermal stability and flame retardancy with the combination of plasticized cellulose acetate and magnesium hydroxide. Furthermore, the level of magnesium hydroxide could be reduced and reasonable flame retardancy maintained compared to the level reported in the literature. The inclusion of the plasticized cellulose acetate and magnesium hydroxide affected some mechanical properties of the material. Polypropylene material containing plasticized cellulose acetate and magnesium hydroxide would be suitable for interior automotive components and other non-structural building materials such as electrical power insulation.
... In this context knowledge about pedestrian dynamics is important and allows e.g. the design and optimization of facilities with respect to safety, level of service and economy. A basic practical application is the capacity estimation which allows the dimensioning or evaluation of facilities [3,4,6,25,30]. For this purpose one is interested in the number of pedestrians, ∆N , which is able to pass the facility in a certain time interval, ∆t. ...
Preprint
Full-text available
Capacity estimation is an important tool for the design and dimensioning of pedestrian facilities. The literature contains different procedures and specifications which show considerable differences with respect to the estimated flow values. Moreover do new experimental data indicate a stepwise growing of the capacity with the width and thus challenge the validity of the specific flow concept. To resolve these differences we have studied experimentally the unidirectional pedestrian flow through bottlenecks under laboratory conditions. The time development of quantities like individual velocities, density and individual time gaps in bottlenecks of different width is presented. The data show a linear growth of the flow with the width. The comparison of the results with experimental data of other authors indicates that the basic assumption of the capacity estimation for bottlenecks has to be revised. In contradiction with most planning guidelines our main result is, that a jam occurs even if the incoming flow does not overstep the capacity defined by the maximum of the flow according to the fundamental diagram.
... Dinenno [18] obtained reliable experimental data by conducting multiple evacuation drills in multistory buildings. They introduced the concept of "effective width" for stairs in their empirical formula for evacuation time. ...
Article
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This research establishes an emergency evacuation time model specifically designed for subway stations with complex structures. The model takes into account multiple factors, including passenger flow rate, subway facility parameters, and crowd density, to accurately assess evacuation times. It considers the impact of horizontal walking distance, flow rate, subway train size, and stair parameters on the overall evacuation process. By identifying bottleneck points such as gates, car doors, and stairs, the model facilitates the evaluation of evacuation capacity and the formulation of effective evacuation plans, particularly in multiline subway transfer stations. The good consistency is achieved between the calculated evacuation time and simulated results using the Pathfinder software (with the relative error of 5.4%). To address urban traffic congestion and enhance subway station safety, the study recommends implemented measures for emergency diversion and passenger flow control. Additionally, the research presents characteristic mathematical models for various evacuation routes by considering the structural and temporal characteristics of metro systems. These models provide valuable guidance for conducting large-scale passenger evacuation simulations in complex environments. Future research can further enhance the model by incorporating psychological factors, evacuation signage, and strategies for vulnerable populations. Overall, this study contributes to a better understanding of evacuation dynamics and provides practical insights to improve safety and efficiency in subway systems.
... The thermal properties extracted from the literature and product data sheets were used for the material properties of the numerical model. The following tables indicate the required thermal properties of the two materials [15][16][17]. The following measurements were made of how the conductivity of aluminium changed with temperature. ...
Conference Paper
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The façade can be defined as the skin of the building, which serves as a barrier against the outside environment. Poor façade performance may result in catastrophic fire spread, building damages, and fatalities during a fire. Façade material, design and layout of the building, and external factors like wind can contribute to the fire spread in high-rise building façades. Conducting large-scale testing to investigate various facade fire scenarios might not be possible due to practical limitations and expensive and time-consuming procedures. To overcome these limitations, using numerical simulation has gained prominence in studying facade fires. Numerical modelling of facade fires can be accomplished using the combined capabilities of Fire Dynamic Simulator (FDS) and PyroSim software which simulates the fire as Computational Fluid Dynamics (CFD) models. In this study, the primary consideration is given to examining the effect of wind on fire propagation along the façade of a high-rise building in Sri Lanka during windy conditions. The reference building (Height: 127 m with 41 floors), having a combustible façade made of Aluminium composite panels and located in Colombo District in Sri Lanka, is modelled using PyroSim software. The fire spread along the façade, the effect of the U-shape geometry of the building, and the influence of wind speed and wind direction (parallel-0 0 , perpendicular-90 0 , angled to the façade surface-45 0) toward the rapid spread of fire are examined using temperature recordings of thermocouples. The results are compared to a reference case of no wind. Results comparison of the validated models has shown a significant impact from the U-shape façade geometry, wind speed, and wind direction for the fire growth and extinguishing along the façade. The findings guide for reducing the rapid spread of devastating façade fires in high-rise buildings during windy conditions.
... From the fire anatomy, the flow field of most of the compartmental fires can be divided into several regions [24], i.e., fire plume region, flow entrainment region, and recirculating region. When studying the fire-induced flow field in more detail, the flow regions are not limited to these three areas. ...
Article
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The flow field driven by a compartment fire usually contains several flow zones with different physical structures. As each type of turbulence model has its own predominant application area, it is logical to apply two or more simple turbulence models to the same fire-induced flow field at different locations according to their predominant features to yield a comparatively simple, accurate, and stable zonal turbulence model. A zonal turbulence model, which is a hybrid of the standard k-ε model and its modification, is developed in this paper. The model is tested and compared with the experimental data. A promising improvement is observed when comparing it with the base turbulence model, i.e., the standard k-ε model, especially in the recirculating region near the corners of the compartment. This approach in having different zones in the plume region will be useful for handling more scenarios at the initial stage of fire hazard assessments.
... The studies on interference between evacuees (people) are usually in terms of clarifying the relationship between walking speed and human density (in the present paper, "human density" refers to the research of pedestrian facilities and buildings, whereas "evacuee density" refers to motorbike lane evacuation) [25,26]. Pauls (1987) studied building evacuation and pointed out that if the human density is less than 0.50-0.54 ...
Article
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In countries with a high motorbike utilization rate, road tunnels can feature motorbike lanes, bringing an additional risk to evacuation from tunnels during a fire or emergency. To better understand the walking speed in motorbike lanes to enhance risk assessment in tunnels, in the present study, we conducted evacuation experiments to investigate the influence of motorbike and evacuee density on the walking speed of motorbike users. According to the experimental results, the walking speed was slightly reduced even when the evacuee density was relatively lower (around 0.1 person/m²). To further analyze the influence of motorbikes in the lane, the walking speed decreased significantly with the increase in motorbike density. The decrease in walking speed presented an exponential relationship with evacuee and motorbike density. Considering this exponential relationship, nonlinear regression was applied to estimate the parameters of the walking speed model. The proposed model consisting of the evacuee density, motorbike density, and free walking speed as variables can serve as an approach to describe the walking speed of motorbike lane evacuation in tunnels.
... A general discussion on the method for measuring smoke from burning materials, specific extinction coefficient of flame generated smoke, and studies the human behavior and tenability in fire smoke is available in the SFPE fire protection handbook (Dinenno, 2008). The implementation steps of a scenario with its FDS modeling is described in details as follow. ...
Article
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High-rise buildings, with high number of population, have always been among the concerns discussed in urban crisis management. One of the crucial aspects of high-rise buildings is having a proper and timely action plan for evacuation in the case of emergencies such as fires. The spread and progression of fire smoke in high-rise buildings are affected by the architectural design of the building, and having a three-dimensional (3D) model of high-rise buildings can play key role in damage reduction in such cases. This paper, first presents a method for 3D smoke emission based on utilizing 2D cadastral data to generate a 3D model of the buildings. Then, in step of smoke fire emission simulation, the influence of different smoke movement paths such as the entrance/exit doors, windows, smoke barrier, stairs, and elevators, are examined in different scenarios. Next, the emergency evacuation of occupancies with different behavioral and physical characteristics is simulated. The results indicate that 2D cadastral data of apartments can be employed as a suitable source to create 3D models of high-rise buildings, and allows to examine the emergency evacuation of residents by including the smoke simulation spread in the building.
... A grid sensitivity study based on DiNenno et al.'s approach [58] was conducted by simulating one of the cases with three scales of mesh sizes, namely coarse (352,000 cells), moderate (1,645,077 cells) and fine (2,841,600 cells). The grid sizes were determined considering characteristic diameter (D*): ...
Article
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In this article, a collective database from validated numerical simulation has been established to study the suppression effects of water-based suppression systems under a single-compartment fire scenario at various suppression configurations and fire locations. Five fuel locations along the axis between the centre and corner of the room were configurated to dynamically analyse how the horizontal distance between the nozzle and fuel pan affects the heat release rate (HRR), temperature cooling phenomena at different heights and also the velocity profile. Throughout the fuel pan relocations, the water-mist system has achieved an average suppression time of 25 s for all the locations, it was found that the water mist system can effectively control the fire under 200 °C that is distanced over 2 m spanwise displacement from the nozzle against the fire, while the sprinkler has exhibited an excellent fuel surface cooling effect due to large momentum and heat capacity within the coverage area with an average suppression time of 50 s. The results of this study have further explored the spray coverage and droplet penetrability of different suppression systems at different locations corresponding to the fire source, and the quantitative assessment of fuel locations could also contribute to the future development of performance-based fire safety designs.
... 43 During thermal degradation, the amorphous region of the polymer is attacked preferentially, so we expected to observe an increase in the crystallinity of the polymer as well as the density for the more degraded nurdles (orange and gray). 72,73 This was not apparent from our bulk density measurements ( Figure 4A). However, the degradation may have only been superficial (changing the surface of the polymer and not the bulk of the polymer) and therefore may not have been substantial enough to affect the bulk density of the degraded nurdles. ...
Article
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In late May 2021, the M/V X-Press Pearl container ship caught fire while anchored 18 km off the coast of Colombo, Sri Lanka and spilled upward of 70 billion pieces of plastic or "nurdles" (∼1680 tons), littering the country's coastline. Exposure to combustion, heat, chemicals, and petroleum products led to an apparent continuum of changes from no obvious effects to pieces consistent with previous reports of melted and burned plastic (pyroplastic) found on beaches. At the middle of this continuum, nurdles were discolored but appeared to retain their prefire morphology, resembling nurdles that had been weathered in the environment. We performed a detailed investigation of the physical and surface properties of discolored nurdles collected on a beach 5 days after the ship caught fire and within 24 h of their arrival onshore. The color was the most striking trait of the plastic: white for nurdles with minimal alteration from the accident, orange for nurdles containing antioxidant degradation products formed by exposure to heat, and gray for partially combusted nurdles. Our color analyses indicate that this fraction of the plastic released from the ship was not a continuum but instead diverged into distinct groups. Fire left the gray nurdles scorched, with entrained particles and pools of melted plastic, and covered in soot, representing partial pyroplastics, a new subtype of pyroplastic. Cross sections showed that the heat-and fire-induced changes were superficial, leaving the surfaces more hydrophilic but the interior relatively untouched. These results provide timely and actionable information to responders to reevaluate cleanup end points, monitor the recurrence of these spilled nurdles, gauge short-and long-term effects of the spilled nurdles to the local ecosystem, and manage the recovery of the spill. These findings underscore partially combusted plastic (pyroplastic) as a type of plastic pollution that has yet to be fully explored despite the frequency at which plastic is burned globally.
... t evac represents the time required for the actual movement of the pedestrian. t marg represents the time for the building to reach its fire-resistance limitation minus RSET [33]. Only when the ASET is greater than RSET can the safety of pedestrians be guaranteed. ...
Article
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Cruise ships are large and complex, and it is difficult to manually make a plan to evacuate people to safe areas in a short time. Evacuation time and personnel safety are both important for emergency evacuation. This paper proposes an evacuation strategy that considers the path capacity and risk level to guide evacuees in fire; it not only ensures the safety of people on dangerous paths but also reduces road congestion to shorten evacuation time. High crowd density means slow moving speed, an exponential function including straight path and stairs speed characteristics is proposed to illustrate the relationship between crowd density and moving speed. Path capacity constraints are used to avoid the congestion caused by the evacuees in a panic. In order to evacuate the evacuees in the risk areas as soon as possible, this paper divides the path into three risk levels according to carbon monoxide concentration, visibility, and temperature along the paths. The people on the higher-risk paths are given higher priority to enter evacuation paths than those on lower risk. The priority strategy evacuates the people on risk paths to safe areas in less time. This paper models the evacuation network topology of a cruise ship and simulates the evacuation process of some situations that have different numbers of evacuees and path capacity constraints. The evacuation strategies and simulation results are guidelines for the crews to guide the people to evacuate to safe areas when there is a fire accident on the cruise ship.
... However, power cables with flammable insulation have been considered to be non-negligible potential fire sources. Fires related to electrical cables have occurred occasionally, resulting in a large number of casualties, major property losses and a serious negative social impact [1]. Therefore, the combustion characteristics of cable materials have been regarded as hot issues. ...
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Cross-linked polyethylene (XLPE) carries a high fire risk. In this paper, a cone calorimeter is used to carry out radiation ignition experiments, and the heat release rate (HRR), mass loss rate (MLR) and other combustion parameters of XLPE cables under three kinds of radiation intensity are measured. By comparing the ignition time and HRR of samples under different conditions, the following conclusions are drawn: (1) The ignition time of XLPE cables decreases significantly with the increase in external thermal radiation intensity. The critical ignition heat flux (CHF) is about 16.24 kW/m². (2) The HRR curve of XLPE is consistent with the characteristics of hot, thick material. The HRR rises rapidly to the first peak after ignition and then rapidly decreases. Then, it slowly rises to the second peak. Finally, it slowly decays until the combustion stops. (3) The first peak values of HRR of XLPE under different radiation intensities are almost the same. The time for the second peak of HRR is shorter, and the value is larger with the increase in external thermal radiation intensity. (4) The cable ignition model is established, which can simulate the cable ignition time well under different radiant heat flow conditions. (5) Based on the mathematical model, the ignition time trend with the thickness of sheath layer and conductive core layer as variables is deduced.
... When the passenger density reaches a certain value, the interference between passengers increases, and the speed of passengers decreases. Previous studies defined the relationship between speed and density as a linear relationship (Navin and Wheeler 1969;Fruin 1970;Older 1967;Lam et al. 1995;Tanaboriboon et al. 1986)that is, the passenger speed decreases monotonically with the increase of density-but further research found that there is a more complex nonlinear downward trend between the two parameters (Tregenza 1976;DiNenno 2008;Rastogi and Chandra 2013). The relationship between passenger speed and passenger density is shown in Fig. 2. ...
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... However, numerous companies have more efficient internal practices and procedures in addition to regulatory guidelines (Persson and Lönnermark 2004;Alimohammadi et al. 2015b;Wells 1997). Adequately designed and efficient installed fire protection systems significantly reduce the risk of asset losses and could mitigate unpleasant events (DiNenno 2008;Mansour 2012). ...
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... Firefighting foam is required for both primary and supplementary purposes, such as the real-time production of foam solution for application on flammable liquid surface using foam pourers for the extinguishment of tank fire and the real-time production of foam solution for application on flammable liquid spills using por-table hose lines for the extinguishment of bund fire, respectively [39]. In addition to fire extinguishment, foam solution can be applied on small oil spills for vapor suppression. ...
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Petroleum facilities containing welded steel bulk flammable liquid product storage tanks possess sundry fire hazards inherent to the facility. These installations urgently require indigenous efficient firefighting systems. So, the efficient design of firewater and firefighting foam system is dynamic in controlling fire-related emergencies. The paper deals with the in-depth conceptualization of the design and analysis of firefighting systems for a typical petroleum handling, processing and storage facility in compliance with international standards. The study is aimed to formulate the elementary technique for designing an optimized firefighting system. The proposed objective was achieved by considering an ideal tank farm site that is most commonly located in a range of terminal stations, pumping stations, petroleum refineries, well sites, etc. Sufficient illumination was enumerated on the standardized classification of the liquid fuel product with respect their flammability range. Special guidelines regarding firefighting system design basis were defined and an optimized firefighting and foam system design was developed. Moreover, sufficient limitations that must be considered during the firefighting of huge tank fires are discussed. This comprehensive numerical design philosophy offers a simple and wide-ranging guide to industrial practitioners by formulating the principles for industrial firefighting system design.
... According to the characteristic length analysis suggested by DiNenno et al. [52], the meshing criteria for the simulation can be determined in the equation below, where D * is the characteristic length, considering the heat release rate Q, density ∞ , specific heat c p and the ambient temperature T ∞ of the air. ...
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Indoor evacuation efficiency heavily relies on the connectivity status of navigation networks. During disastrous situations, the spreading of hazards (e.g., fires, plumes) significantly influences indoor navigation networks’ status. Nevertheless, current research concentrates on utilizing classical statistical methods to analyze this status and lacks the flexibility to evaluate the increasingly disastrous scope’s influence. We propose an evaluation method combining 3D spatial geometric distance and topology for emergency evacuations to address this issue. Within this method, we offer a set of indices to describe the nodes’ status and the entire network under emergencies. These indices can help emergency responders quickly identify vulnerable nodes and areas in the network, facilitating the generation of evacuation plans and improving evacuation efficiency. We apply this method to analyze the fire evacuation efficiency and resilience of two experiment buildings’ indoor networks. Experimental results show a strong influence on the network’s spatial connectivity on the evacuation efficiency under disaster situations.
... and The fire event starts with the following settings: the fire source is on every node in the navigation network in each simulation, and the zero-moment for the fire emergency is under phase 2. In this phase, the accessibility of the neighboring nodes within a specific scope of the fire source is disabled. We set this scope with parameters defined in the SFPE handbook under the normal fire spreading conditions: the fire affected areas grow with a speed of 0.0015 m/s for 280 seconds and with a developing rate of 0.30 m/s for 140 seconds [46]. Exit nodes for the MLC building are node 1111, node 111122, node 111164, node 111155 and node 111158. ...
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Indoor evacuation efficiency relies on the robust connectivity status of navigation networks. In real situations, the original network status and disaster development codetermine this status. Nevertheless, current research concentrates on utilizing classical statistical methods to analyze the connectivity of navigation networks and lacks the flexibility to evaluate the spatial influence introduced by disasters. To address this issue, we devise a solution that can merge an indoor navigation graph with the 3D spatial distribution and analyze its connectivity status. Additionally, the proposed method can also be used to design strategies for recovering fragmented networks. Experimental results show the positive influence of spatial connectivity features on key evacuation network elements, such as shortening evacuation distance and fast-identifying safe evacuation area and provides the application pattern of this spatial feature to improve evacuation efficiency. In general, we can apply this method to the analysis of fire evacuation efficiency and resilience for 3D indoor navigation networks.
... Indeed, early modelling and experimental investigations have revealed the importance of the skin biothermics that should account for sudation and organism thermoregulation [1]. On the other hand, recent firefighter clothing technologies have evidenced the multilayered configuration of the textile, which have to be separated by several air-gaps to enhance the thermal resistance [2]. A concise analysis on the characterization of multilayer fabrics has highlighted the contribution of convective, radiative and conductive thermal exchanges within the clothingbody assembly [3]. ...
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In the present work, an unsteady analysis is carried out for the thermal characterisation of a firefighter protective clothing. Coupled radiative and conduction heat transfers are considered inside the clothing with a focus on the thermal level on the first skin layer. The protective garment is modelled as a 1D solid medium, featuring three layers of tissues, separated by several air-gaps. A parametric analysis is performed in the aim to predict the effect of conductive and radiative tissue's properties fluctuation on the first skin's layer temperature. The thermal balance equations are written in a finite element (FE) formulation and solved using the COMSOL Multiphysics® software. Predictions were provided for the temperature and heat flux distributions in the fabric, skin, and air-gap as a function of time, as well as the time to receive skin burn injuries. The results obtained were compared with stationary 2-D calculations, and faced to unsteady simulations, based on the finite volume method. A 50% relative reduction in the absorptivity of the skin (in the case of wearing a fine knitted fabric) makes it possible to reduce the surface temperature of the skin to a tolerable value.
... Aqueous film-forming foam (AFFF) can rapidly spread on the surface of flammable liquids and form a dense and stable foam layer that acts a physical barrier against the heat and mass transfer, thus exhibiting excellent cooling and covering isolation effects in hydrocarbon fire especially in oil pool fire [1,2]. Lee et al. [3] found that AFFF acquires the optimum fire-extinguishing effect in oil pool fire at a gas-liquid ratio of 1:7, and the incorporation of surfactant in the foam liquid is beneficial to improve the fire-extinguishing performance of the foam. ...
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A laboratory fire-extinguishing system was applied to investigate the effect of gas-liquid ratio on the fire-extinguishing performance of aqueous film-forming foam (AFFF) in diesel pool fire, and the proposed fire-extinguishing mechanism of AFFF is carefully analyzed. The results show that the AFFF foam possesses the shortest extinguishing time of 42s and lowest foam liquid consumption of 210 g at a gas-liquid ratio of 16, exhibiting the best fire-extinguishing performance. Chemical analysis of AFFF indicates that a proper gas-liquid ratio is beneficial to enhance the expansion ratio and drainage rate of AFFF that affect the cooling and covering effects of foam, thus achieving the optimum fire-extinguishing efficiency. Infrared thermal imaging analysis indicates that the main fire-extinguishing mechanism of AFFF is mainly ascribed to the superior cooling, covering and suffocating effects of foam against the transfer of heat and oxygen, thus effectively preventing the underlying fuel from further combustion.
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This study focuses on XLPE-insulated cables used in nuclear power plants. A cone calorimeter was employed to measure the combustion characteristics of the cables, and Pearson correlation analysis was innovatively introduced to evaluate the relationships among the combustion characteristic parameters. The results indicate that both thermal and non-thermal risks associated with the cables increase with rising external heat flux. The Time to Ignition (TTI) at a radiant heat flux of 25 kW m−2 is approximately five times greater than that at 50 kW m−2, and about ten times greater than that at 75 kW m−2. The TTI of the cables exhibits a linear correlation with their refractory properties. A strong positive linear relationship is observed between the peak of Heat Release Rate (HRR) and radiant heat flux, as well as between the mean of HRR and Mass Loss Rate (MLR). Both MLR and HRR demonstrate higher peaks and shorter times to peak under elevated heat flux conditions. Additionally, the sheath's physical properties significantly influence the cable's combustion characteristics; specifically, HRR decreases as the number of conductors in the cable increases and as the cable diameter expands. XLPE, when used as an insulating layer, provides superior flame retardancy compared to its use as a sheath.
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In South Korea, the need to link fire and evacuation simulations to compare the available safety egress time (ASET) and required safety egress time (RSET) in real time when implementing performance-based design in buildings is increasing. Accordingly, the Consolidated Model of Fire Growth and Smoke Transport (CFAST) has been discussed as an alternative to the fire dynamics simulator, which requires high computational costs, sufficient experience in fire dynamics numerical calculations, and various input parameters and faces limitations in integration with evacuation simulations. A method for establishing a reasonable computational domain to predict the activation times of smoke and heat detectors has been proposed. This study examined the validity of using CFAST to predict factors relevant to the ASET evaluation. The results showed that CFAST, which solved empirical correlations based on heat release rates, predicted high gas temperatures similarly. Moreover, the applicability of the visibility distance calculation method using smoke concentration outputs from CFAST was examined. The results suggest that despite the limitations of the zone model, CFAST can produce reasonable ASET results. These results are expected to enhance the usability of CFAST in terms of understanding general fire engineering technology and simple fire dynamics trends.
Chapter
Heat flux is a major issue that must be considered for evacuation, fire spread and structure protection in tunnel fires. The three heat transfer mechanisms – convective, radiative and conductive heat transfer – are described with a focus on correlations related to tunnel fires. The Reynolds-Colburn analogy is introduced as a basis for the calculation of convective heat transfer. Characteristics of the absorbing, emitting and scattering gases are summarized, together with radiation between multiple surfaces. Analytical solutions for heat conduction into tunnel walls are summarized for different types of simplified boundary conditions. The overall heat transfer from flames and gases to the tunnel structure involves all three heat transfer mechanisms; their correlations are illustrated using an electrical circuit analogue. Simple models for calculating heat flux in small and large tunnel fires are presented with a focus on radiation. Correlations for incident heat flux are proposed and verified for small and large fires in tunnels, taking radiation from both flames and smoke into account. Different radiation models used for jet flames in an open environment are also discussed.
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Walking speed is a significant aspect of evacuation efficiency, and this speed varies during fire emergencies due to individual physical abilities. However, in evacuations, it is not always possible to keep an upright posture, hence atypical postures, such as stoop walking or crawling, may be required for survival. In this study, a novel 3D passive vision-aided inertial system (3D PVINS) for indoor positioning was used to track the movement of 20 volunteers during an evacuation in a low visibility environment. Participants’ walking speeds using trunk flexion, trunk–knee flexion, and upright postures were measured. The investigations were carried out under emergency and non-emergency scenarios in vertical and horizontal directions, respectively. Results show that different moving directions led to a roughly 43.90% speed reduction, while posture accounted for over 17%. Gender, one of the key categories in evacuation models, accounted for less than 10% of the differences in speed. The speeds of participants under emergency scenarios when compared to non-emergency scenarios was also found to increase by 53.92–60% when moving in the horizontal direction, and by about 48.28–50% when moving in the vertical direction and descending downstairs. Our results also support the social force theory of the warming-up period, as well as the effect of panic on the facilitating occupants’ moving speed.
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In performance-based design for domestic buildings, there is a growing need for real-time comparison between the Available Safe Egress Time and Required Safe Egress Time through the integration of fire and evacuation simulations. Therefore, the utilization of the Consolidated Model of Fire and Smoke Transport (CFAST) has been discussed as an alternative to the Fire Dynamics Simulator (FDS), which has high computational costs; requires sufficient experience in the numerical calculation of fire dynamics, along with various input parameters; and has limitations in coupling with evacuation simulations. In this study, the prediction performance of CFAST for the activation times of smoke and heat detectors was evaluated. Specifically, it is essential to configure the mass movement between adjacent computational regions for smoke concentration. For achieving adequate predictive performance, the temperature should be determined according to the ceiling jet velocity generated by the fire source. Therefore, a method for setting a computational domain that can produce reasonable prediction results while considering the characteristics of CFAST for different types of smoke and heat detectors is proposed.
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The spontaneous combustion of hay when stacked after baling is an issue frequently encountered by farmers in Australia and elsewhere. While there is a basic understanding of why this occurs the interactions of the many factors involved mean that there is still no consistent methodology for its prevention. Recent technological advances in sensors and communications allow for the continual collection of quantitative data from hay bales or stacks for managers to utilize in their decision-making processes with regards to minimizing the risks of spontaneous combustion. This review discusses both the factors involved in the spontaneous combustion of haystacks and the types of sensors available for the monitoring of these factors. This includes advancements in sensor technologies and their practical applications in monitoring hay bale conditions.
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This study aimed to calculate the habitable time using a fire and evacuation simulation program for an in-operation nursing hospital, compare and analyze it with the required evacuation time, and suggest a plan to enhance evacuation safety. The habitable time was calculated through fire simulations by assuming that a fire was caused by the careless handling of heating appliances in a doctor’s office. The evacuation time required for the occupants of the nursing hospital, including those who could not evacuate themselves, was compared and analyzed with the habitable time through the evacuation simulation. In the simulation, nursing hospitals of two stories or higher were not mandated to install ramps or elevators, per the current standards. The evacuation time of the nursing hospital subjected to this experiment exceeded the habitable time; hence, evacuation safety was not ensured. Through evacuation time analysis, we sequentially compared and analyzed the cases where those who were unable to evacuate on their own would evacuate using only the ramp, or only the elevator, or both, the ramp and the elevator. Additionally, the cases in which additional evacuation spaces were installed were also analyzed for the three situations. The evacuation simulation results demonstrated that the evacuation time significantly increased in other instances compared with the cases where ramps, elevators, and evacuation spaces were all installed. The results indicate that all nursing hospitals that are two stories or higher should be required to install all ramps, elevators, and evacuation spaces by amending related laws.
Chapter
The three examples of applications of the fire hazards analysis considered are intended to represent realistic situations in which the ideas presented in this guide can be used. The examples and the results presented are hypothetical, are illustrative, and do not necessarily correlate precisely. The goal of this section is to demonstrate the process and the interrelation of various aspects of the analysis.
Chapter
The second task in the room of origin fire hazards analysis is to obtain the input data necessary to conduct the evaluation. Two basic types of data are required for a fire hazards analysis:
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Featured Application This study provides confidence in the application of the zone model to describe fire growth and smoke transport in compartments where complex and multiple fuels are involved. Abstract This paper presents the development and validation of a two-zone model to predict fire development in a compartment. The model includes the effects of the ceiling jet on the convective heat transfer to enclosure walls and, unlike existing models, a new concept of surrogate fuel molecule (SFM) to model multi-fuel combustion, and a momentum equation to accurately track the displacement of the smoke layer interface over time. The paper presents a series of full-scale fire experiments conducted in the IUSTI fire laboratory, involving different combinations of solid and liquid fuels, and varying the compartment confinement level. The model results are compared to the experimental data. It was found that for all fire scenarios, the experimental trends are well reproduced by the model. The SFM concept predicts oxygen and carbon dioxide concentrations in the extracted smoke to within a few percent of the measurements, which is a good agreement considering the sensitivity of the model to chemical formulas and combustion properties of fuels. Comparison with other measurements, namely average gas and wall temperatures, is also good. For the large fires reported in this study, the impact of the ceiling jet leads to a slight underestimation of wall temperatures, while the model gives conservative estimates for small fires.
Chapter
Zur Beurteilung des Brandverhaltens von Baustoffen und Bauteilen werden Materialdaten der verschiedensten Art verwendet. Auch für Ingenieurmethoden im Brandschutz sind eine Reihe an Materialdaten erforderlich. Im vorliegenden Beitrag werden vor allem Materialkennwerte behandelt, welche für die praktische Anwendung von Rechenverfahren besonders wichtig sind.
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Understanding and characterisation of the pyrolysis and burning behaviour of flame retardant (FR) polymers are essential towards optimising the end-product in terms of flammability, charring, toxicity and smoke reduction. This study proposes a modelling framework to study the combustion behaviour, pyrolysis kinetics and FR mechanisms of FR treated polymer composites. This numerical framework has utilised reactive molecular dynamics (MD-ReaxFF) simulations to characterise the pyrolysis kinetics, char formation and residues fragments of High-density polyethylene (HDPE) and Ammonium polyphosphate filled HDPE (HDPE/APP) composites. Through MD characterisation of the polymer breaking process, thermal degradation behaviours are described by reactions rates in Arrhenius form and subsequently imported into the computational fluid dynamics (CFD) models. The modelling framework has well-predicted the heat release rate (HRR) profiles, ignition time and combustion duration of the HDPE and HDPE/APP composites, where average relative errors less than 15% were achieved compared to thermogravimetric analysis (TGA) and cone calorimeter tests. The proposed numerical framework demonstrated the capability to capture the burning behaviour and flammability of FR treated polymer composites and identify the pyrolysis kinetics and FR mechanisms offered by the APP additives, such as dehydration and char formation.
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Owing to the increased depletion risk and cost of phosphate mines, the demand for low phosphorus or ecological phosphorus flame inhibitor is increasing. This study reports an experimental exploration of the combustion inhibition efficiency of bio-based transition metal complex materials containing iron and phosphorus, namely, iron @ phosphorus complex (Fe-PMC). The aim is to develop a new type of flame inhibitor with an iron-phosphorus interaction effect to replace pure phosphorus extinguishing agents. The synthesis of Fe-PMC was characterized by Fourier-transform infrared spectroscopy, X-Ray diffraction, X-ray photoelectron spectroscopy and Scanning electron microscope. The Fe-PMC (ⅰ) is the mesh porous structure connected by the accumulation of small particles, (ⅱ) is an amorphous structure with many binding sites exposed and excellent interface compatibility, (ⅲ) contains no chloride ions. Suppression tests and thermogravimetric measurements indicate that (ⅰ) Fe-PMC has a higher combustion inhibition ability than MIL-53 containing only iron, especially at low concentrations, (ⅱ) Fe-PMC reduces the laminar flame velocity of cellulose, (ⅲ) Fe-PMC greatly reduces flame temperature. The activation energy (E), pre-exponential factor (A) and char yield (Y) of cellulose pyrolysis were determined by kinetic analysis. It concluded that MIL-53 and Fe-PMC produce combustion inhibition mainly in the solid phase. These findings will contribute to the development of a flame inhibitor with low or no phosphorus and better performance.
Conference Paper
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Smoke propagation in tunnel fires was and still is in the focus of intense research. The main aim of such investigations is the critical velocity required to avoid backlayering or the definition of the length of a backlayer. This paper compares results from in-situ measurements, from 3D CFD simulations, and from the application of literature-based simple equations. Since smoke propagation is strongly influenced by numerous parameters such as heat release rate, supply air velocity, temperature and humidity, the fire source itself, etc., boundary conditions have to be defined clearly when comparing results from the different types of investigations. A special focus in this paper is the behavior of the backlayering in small and mid-size pool-fires under varying conditions. The starting point was well documented full-scale fire tests performed in the Koralmtunnel in winter 2017/2018. 3D CFD models were applied, allowing for a detailed analysis of smoke propagation and a comparison with full scale fire tests. Finally, the results concerning backlayering length were compared to results achieved by application of well-known equations from literature. SYMBOLS backlayering length [m] dimensionless backlayering length * heat release rate [kW] ̇ dimensionless heat release rate * supply air velocity [m/s] dimensionless supply air velocity * tunnel height [m] tunnel cross section area [m²] supply air temperature [K] 0 gravity acceleration [m/s²] supply air density [k/m³] 0 specific heat-air [kJ/kgK]
Chapter
Describes the fire experiments that were used to provide the data that was compared against DETACT-QS predictions. The geometry, heat detector characterizations, and heat release rate data needed for DETACT-QS input are provided. Information that helps to characterize the experimental conditions beyond the input data needed for DETACT-QS is also given to provide as complete a description of the experimental scenario as possible. Uncertainties and assumptions from the measurements in the experiments are also discussed.
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The safety process and effectiveness of in situ burning (ISB) method dealing with spilling liquids depend on flame morphology, mass burning rate and flame radiation. In this work, eight rectangular pools with a fixed area of 400 cm² but different aspect ratios (length–width ratio, n = 1, 2, 4, 6, 8, 10, 12, and 16, respectively) are used. As the aspect ratio increases from n = 1 to n = 16, the flame height decreases from 105.6 to 72.9 cm, whereas the incident heat flux increases from 0.283 to 0.562 kW/m². The mass burning rate decreases initially at n ≤ 6 and increases afterwards at n > 6. The traditional flame radiation model overestimates experimental measurement because the radiation model assumes that the flame surface is rectangular, but the actual flame shape shows a trapezoidal surface due to air entrainment. The mathematical linear interpolation method is proposed to make an improvement of rectangular radiation model. The new‐proposed flame radiation model is validated by experimental measurements with the relative error < 5%. The current work provides a good method to evaluate the magnitude of loss prevention of oil leakage.
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Significance A topic of special interest in crowd dynamics that can lead to better infrastructure management is the study of people under high competitiveness. Persons fleeing from real danger is one instance of this scenario, but of course it is difficult to analyze it experimentally. This is why people running with bulls at the San Fermín Festival provides an exceptional annual event where real data of pedestrian dynamics under extreme conditions can be collected. This kind of data is scarce and therefore highly valuable.
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The widely used alkyd resin suffers not only the flammability but also the autoignition of resin waste. Its autoignition should result from the air-drying exothermic effect due to autoxidation and conversion of double bond. However, the air-drying exothermic effect is seldom studied. In this study, five soybean oil-based alkyd resins were synthesized. The content of double bond measured by the titration method increased linearly with increasing the molar fraction of maleic anhydride. After air-drying, the infrared spectroscopy absorption peak for the double bond disappeared. Considering that the curing originated from the conversion of chemical bonds, the exothermic effect was theoretically analyzed to be 1163–1455 kJ mol−1 double bond based on the air-drying mechanisms and the differences among chemical bond energies. According to thermodynamics principles, the air-drying exothermic effect was also derived from the measured heat of combustion. When the content of double bond increased from 2.19 mol kg−1 resin to 2.56 mol kg−1 resin, the exothermic effect linearly increased from 1352 kJ mol−1 double bond or 2.96 kJ g−1 resin to 2508 kJ mol−1 double bond or 6.42 kJ g−1 resin. The steady and unsteady autoignition theoretical analyses implied that due to the air-drying exothermic effect the alkyd resin waste with a certain thickness would catch fire within one working day.
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Background Storage tanks in oil and gas processing facilities contain large volumes of flammable compounds. Once the fuel-air mixture is ignited, it may break out into a large fire or explosion. The growing interest in monitoring air quality and assessing health risks makes the evaluation of the consequences of a fire an important issue. Atmospheric dispersion models, which allow for simulation of the spatial distribution of pollutants, represent an increasingly widespread tool for this type of evaluations. Objectives The present study discusses the set up and results of a modeling study relevant to a hypothesized fire in an oil refinery. Methods After choosing the most suitable dispersion models, i.e. the Lagrangian model SPRAY and the puff model CALPUFF, estimation of the required input data is discussed, focusing on the source variables, which represent the most uncertain input data. The results of the simulations were compared to regulatory limits to effectively evaluate the environmental consequences. Finally, a sensitivity analysis was employed to identify the most influential variables. Results The simulation results revealed that ground concentration values were far below the cited long-term limits. However, the most interesting outcome is that depending on the dispersion model and the source type modeled, different results may be obtained. In addition, the sensitivity study indicates that the source area is the most critical variable, since it determines a significantly different behavior depending on the modeled source types, producing, in some cases, variability in the pollutant ground concentrations on selected receptors up to +/− 60%. Conclusions Depending on the selected model and the algorithms available to describe the physics of emission, the results showed a different sensitivity to the input variables. Although this can be explained from a mathematical point of view, the problem remains of choosing case by case the option that best approximates the real behavior of the incidental source under investigation. Competing Interests The authors declare no competing financial interests.
Conference Paper
div class="section abstract"> In order to further understand the sequence of events leading to stochastic preignition in a spark-ignition engine, a methodology previously developed by the authors was used to evaluate the propensity of a wide range of fuels to establishing propagating flames under conditions representative of those at which stochastic preignition (SPI) occurs. The fuel matrix included single component hydrocarbons, binary mixtures, and real fuel blends. The propensity of each fuel to establish a flame was correlated to multiple fuel properties and shown to exhibit consistent blending behaviors. No single parameter strongly predicted a fuel’s propensity to establish a flame, while multiple reactivity-based parameters exhibited moderate correlation. A two-stage model of the flame establishment process was developed to interpret and explain these results. In short, the fuel-air mixture must locally reach a chemical run-away ignition temperature and then the fuel-air mixture outside of this zone must sustain a propagating flame. This model explains why various fuel properties affect the overall flame establishment propensity of a given fuel. The data of this study, and the understanding it has generated, helps elucidate the role of fuels on the flame establishment process under elevated pressure and temperature conditions, and ultimately aids in the understanding of the stochastic preignition problem. </div
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