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This work revisits the principle characteristics of two unique regimes of behaviour of fully-developed compartment fires first identified during the immense body of research that came to define the compartment fire framework. Expe...
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This work revisits the principle characteristics of two unique regimes of behaviour of fully-developed compartment fires first identified during the immense body of research that came to define the compartment fire framework. Experimentation and computational modelling are used to explore, compare and contrast the characteristics of these two Regimes and identify the transition or break point between the two. Their relevance to the design of contemporary infrastructure and need for a greater understanding of both Regimes in this context is discussed. (C) 2015 Elsevier Ltd. All rights reserved.
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A fire resistance design has been applied for the safety of the structure in preparation for the fire that occurred in the building. However, there might be a limit to considering the various fire elements in the design. Particula...
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A fire resistance design has been applied for the safety of the structure in preparation for the fire that occurred in the building. However, there might be a limit to considering the various fire elements in the design. Particularly, for a natural fire curve, it is difficult to evaluate the structure's fire resistance performance through a full-scale fire test. Thus, the standard fire curve, developed based on time-temperature, has been used instead. In a bid to evaluate the fire resistance performance using the natural fire curve, the procedure proposing that the natural fire curve was first developed depending on the fire load and opening area through the fire test in the compartment, which is then equivalently substituted into the standard fire curve with the same fire load value, was proposed in this study. Heat transfer analysis was performed to verify whether the equivalent-substituted fire curve causes the same temperature gain as the natural fire curve. By comparing the two values, a significantly similar value was found around 20℃.
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In this paper we perform predictive simulations of liquid pool fires in mechanically ventilated compartments. We show that steady state burning rates are accurately predicted using a detailed model for the liquid phase heat transf...
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In this paper we perform predictive simulations of liquid pool fires in mechanically ventilated compartments. We show that steady state burning rates are accurately predicted using a detailed model for the liquid phase heat transfer. The effect of lowered oxygen vitiation on the burning rate of pool fires is correctly captured. Simulations were done using the Fire Dynamics Simulator and the experiments considered were conducted in the OECD PRISME project. The main difference between the present study and previous simulation studies is the use of a detailed liquid evaporation model and the direct calculation of the vitiation and thermal environment interactions through the CFD solver.
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An important cause of fire departure in industrial facilities is due to electrical origin and particularly to electrical cabinets. The investigation of such fires has been scarce up to now and has been investigated exclusively in ...
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An important cause of fire departure in industrial facilities is due to electrical origin and particularly to electrical cabinets. The investigation of such fires has been scarce up to now and has been investigated exclusively in the nuclear industry. The Institut de Radioprotection et de Surete Nucleaire (IRSN) conducted a large number of experiments involving electrical cabinets burning either under a calorimetric hood or inside a mechanically ventilated compartment to investigate this topic. Calori-metric hood experiments demonstrated that the most important parameter is the size of the vents of the cabinet and that the time to flashover depends on many factors and seems somewhat random with regard to the observable parameters. The influence of the compartment on the fire behavior depends on the temperature of the surrounding atmosphere of the cabinet and on the oxygen content in the compartment at the level of the inlet vent of the cabinet. The compartment strongly impacts the pyrolysis of the combustible, affecting the fire duration, but has a weak effect on the Heat Release Rate (HRR). Experiments were usually remarkably reproducible, opening the way to a phenomenolo-gical description of this type of fire. A semi-empirical model based on the coupled solution of ventilation limit and excess pyrolysate could then be developed. This model was introduced in a zone code, and an ad-hoc modeling of the fire extinction based on a critical surfacic mass loss rate is proposed. The major features of the compartment fire experiments such as characteristic HRR and fire duration could then be reproduced with acceptable error. The development of such a semi-empirical model is a common practice in fire safety engineering concerned with complex combustibles.
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Developments in the understanding of fire behaviour for large open-plan spaces typical of tall buildings have been greatly outpaced by the rate at which these buildings are being constructed and their characteristics changed. Nume...
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Developments in the understanding of fire behaviour for large open-plan spaces typical of tall buildings have been greatly outpaced by the rate at which these buildings are being constructed and their characteristics changed. Numerous high-profile fire-induced failures have highlighted the inadequacy of existing tools and standards for fire engineering when applied to highly-optimised modern tall buildings. With the continued increase in height and complexity of tall buildings, the risk to the occupants from fire-induced structural collapse increases, thus understanding the performance of complex structural systems under fire exposure is imperative. Therefore, an accurate representation of the design fire for open-plan compartments is required for the purposes of design. This will allow for knowledge-driven, quantifiable factors of safety to be used in the design of highly optimised modern tall buildings. In this paper, we review the state-of-the-art experimental research on large open-plan compartment fires from the past three decades. We have assimilated results collected from 37 large-scale compartment fire experiments of the open-plan type conducted from 1993 to 2019, covering a range of compartment and fuel characteristics. Spatial and temporal distributions of the heat fluxes imposed on compartment ceilings are estimated from the data. The complexity of the compartment fire dynamics is highlighted by the large differences in the data collected, which currently complicates the development of engineering tools based on physical models. Despite the large variability, this analysis shows that the orders of magnitude of the thermal exposure are defined by the ratio of flame spread and burnout front velocities (V_S/ V_(BO)), which enables the grouping of open-plan compartment fires into three distinct modes of fire spread. Each mode is found to exhibit a characteristic order of magnitude and temporal distribution of thermal exposure. The results show that the magnitude of the thermal exposure for each mode are not consistent with existing performance-based design models, nevertheless, our analysis offers a new pathway for defining thermal exposure from realistic fire scenarios in large open-plan compartments.
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We analysed the hydrogen generation during the smouldering of polymeric materials, which are typically used in the household, in the Smoke Density Chamber coupled to a new developed hydrogen sensor to detect early stages of fires....
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We analysed the hydrogen generation during the smouldering of polymeric materials, which are typically used in the household, in the Smoke Density Chamber coupled to a new developed hydrogen sensor to detect early stages of fires. The results of hydrogen generation were compared with the emission of carbon monoxide and smoke during the fire scenarios. Additionally, the results were compared with parameters used in traditional commercial detection systems. In this scenario, the hydrogen sensor showed encouraging results for the detection of fires in earlier phase compared to traditional detectors. Furthermore, we tested the new developed hydrogen sensor in a real room with different fire scenarios. We have also investigated interferences, e.g. steam and cigarette smoke. The hydrogen sensor could detect hydrogen generation in the earliest stage of fire, even before CO and smoke were developed in detectable amounts. Therefore, the hydrogen sensor can be applied for early fire detection in case of pyrolysis. The sensors are quite good for detecting pyrolysis gases. But when it comes to a fast ignition other techniques are more suitable for it. The sensors are best for combination with other techniques, such as smoke detectors.
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An experimental study was conducted to investigate the thermal, chemical, and flow environments of heptane fires in an ISO 9705 room. Fuel flow rates and vent size were manipulated to create overventilated fire (OVF) and undervent...
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An experimental study was conducted to investigate the thermal, chemical, and flow environments of heptane fires in an ISO 9705 room. Fuel flow rates and vent size were manipulated to create overventilated fire (OVF) and underventilated fire (UVF) conditions. Numerical simulations were also performed, for the same conditions, with the Fire Dynamics Simulator (FDS) developed at the National Institute of Standards and Technology. Both OVF and UVF conditions were characterized with temperature distributions, and combustion product formation measured locally in the upper layer, as well as combustion efficiency and global equivalence ratio. It was shown that the numerical results agree quantitatively with measurements in both OVF and UVF. The internal flow pattern rotated in the opposite direction for the UVF relative to the OVF so that a portion of products recirculated to the inside of compartment. This flow pattern may affect changes in the complex processes of CO and soot formation inside the compartment due to an increase in the residence time of high-temperature products. The 3D flow structures including O_2 and CO distribution were visualized inside the underventilated compartment fire using FDS. It was observed that the two gas sample locations in the upper layer of the room were insufficient to completely characterize the internal structure of the compartment fire.
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Purpose - In the frame of the European RFCS TRAFIR project, three large compartment fire tests involving steel structure were conducted by Ulster University, aiming at understanding in which conditions a travelling fire develops, ...
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Purpose - In the frame of the European RFCS TRAFIR project, three large compartment fire tests involving steel structure were conducted by Ulster University, aiming at understanding in which conditions a travelling fire develops, as well as how it behaves and impacts the surrounding structure. Design/methodology/approach - During the experimental programme, the path and geometry of the travelling fire was studied and temperatures, heat fluxes and spread rates were measured. Influence of the travelling fire on the structural elements was also monitored during the travelling fire tests. Findings - This paper provides details related to the influence of travelling fires on a central structural steel column. Originality/value - The experimental data are presented in terms of the gas temperatures recorded in the test compartment near the column, as well as the temperatures recorded in the steel column at different levels. Because of the large data, only fire test one results are discussed in this paper.
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Our understanding of fire behaviour and heating conditions for load-bearing structural elements was developed from an immense body of research in small under-ventilated compartment fires. Within the context of contemporary archite...
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Our understanding of fire behaviour and heating conditions for load-bearing structural elements was developed from an immense body of research in small under-ventilated compartment fires. Within the context of contemporary architecture, large open-plan compartments are commonplace, yet understanding of the first principles that define fire behaviour in such enclosures remains limited. Past experiments have revealed that fires in open-plan compartments exhibit three distinct fire spread modes: a fully-developed fire, a growing fire, and a travelling fire. This paper studies the thermal characteristics arising from these fire spread modes and the effects of the ventilation imposed. An experimental analysis of the energy distribution and spatial heating is conducted on a series of large-scale compartment fire tests, with the fire spread mode and ventilation conditions systematically varied. Each fire spread mode is shown to induce significant and characteristic spatial heat distributions. Moreover, the analysis of the ventilation modes shows equivalent thermal loads imposed on the structure in cases where the opening areas are large, and plume flows are dominant despite lower gas temperatures and irradiation. Thus, fires in open-plan compartments pose unique and possibly more severe thermal loading to structural systems, a characteristic not captured by current design fire methodologies.
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The objective of this work is to show how a sensitivity study based on a fractional factorial design can be helpful to quantify the impact of parameter variations on model predictions. These parameters have been carefully chosen d...
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The objective of this work is to show how a sensitivity study based on a fractional factorial design can be helpful to quantify the impact of parameter variations on model predictions. These parameters have been carefully chosen due to their high variability in fire modeling and the analysis is conducted by simulating a compartment fire with a CFD model. Through a rigorous approach, it is demonstrated that this fractional design composed of eight simulations gives the same information as a standard full design of 64 runs. Physically, it is found that some turbulence and combustion parameters are significant for most the responses.
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