scholarly journals A Study on Fire Spread and Evacuation Risk of Conduit Combustion in Ceiling Hiding Place

2020 ◽  
Vol 34 (1) ◽  
pp. 55-65
Author(s):  
Kwang-Muk Park ◽  
Jae-Kam Jeon ◽  
Sun-Bae Bang
Keyword(s):  
Risk Analysis ◽  
Fire Spread ◽  
Heat Emission ◽  
Measured Data ◽  
Total Heat ◽  
Synthetic Resin ◽  
Hiding Place ◽  
Evacuation Risk ◽  
Combustion Tests ◽  
Fire Spreading

In this study, the ISO 5660 and ISO 5659 combustion tests were conducted with synthetic resin conduits (CD, VE) and metal conduit (ST) used for wiring work in electrical facilities, which can be installed in ceiling concealed places. Then, fire spreading and evacuation risks were analyzed based on the measured data. In the ISO 5660 test, CD of 120.5 MJ/㎡, VE of 81.9 MJ/㎡, and ST of 4.9 MJ/㎡ were measured. In the ISO 5659 test, the CD 1320, VE 731, and ST 102 were measured, and then the maximum smoke densities were measured for CD 605 s, VE 740 s, and ST 1,200 s. In terms of fire spreading and evacuation risk, the CD conduit, VE conduit, and ST conduit were in order. In the fire spreading risk analysis, total heat emission was calculated as 4,820 MJ/㎡, 4,267 MJ/㎡, and 196 MJ/㎡ for CD, VE, and ST, respectively. Evacuation risk analysis shows at transmittance of 89%, CD is 127 s, VE is 35 s, and ST is 969 s. At transmittance of 79%, representing almost invisible concentration, CD is 157 s and VE is 50 s. The CD and VE conduits had a high fire spreading and evacuation risks, while the ST conduit had little effect on fire spreading and evacuation risk.

Fire spreading experiments on heterogeneous fuel beds. Applications of percolation theory

2000 ◽  
Vol 30 (8) ◽  
pp. 1318-1328 ◽  
Author(s):  
Jean Nahmias ◽  
Hervé Téphany ◽  
José Duarte ◽  
Sophie Letaconnoux
Keyword(s):  
Experimental Work ◽  
Percolation Theory ◽  
Dynamic Behaviour ◽  
Fire Spread ◽  
Directed Percolation ◽  
Final State ◽  
Critical Thresholds ◽  
Scale Models ◽  
Different Types ◽  
Fire Spreading

In the experimental work presented here, fire spread was studied through various laboratory and full-scale models containing different types of combustible and noncombustible materials. We have examined the dynamic behaviour of the flame front and the final state (after extinction) on randomly created heterogeneous zones, both with and without wind. The principal conclusion is that critical thresholds exist, for the ratio between combustible and noncombustible parts, at the transition between nonpropagation and propagation of the fire. This result is common to all types of spreading (with or without wind). The values of the critical thresholds in the nonwind-driven experiments are those of the percolation theory. The critical exponent, obtained for wind-driven experiments, is in accordance with current values suggested by the directed percolation approach.

scholarly journals A Comparative Analytical Study of Some External Finishing (Cladding) Material in Terms of Their Ability to Spread Fire in Multi-story Building Facades in Iraq

2020 ◽  
Vol 10 (5) ◽  
pp. 647-654
Author(s):  
Ahmed A. Alfakhry
Keyword(s):  
Computer Modeling ◽  
Analytical Study ◽  
Raw Materials ◽  
Fire Spread ◽  
Building Facades ◽  
The Difference ◽  
Fire Spreading ◽  
Story Building ◽  
Cladding Material ◽  
Main Factor

The traditional building in Iraq characterised by the using of a certain number of finishing's in external façades like cement plastering, limestone and perforated yellow brick because the raw materials of manufacturing are available locally. Fire spread through the facades is widely recognized as one of the fastest pathways of fire spreading in the buildings, so the appropriate choose of highly performance finishing material against fire will be potentially the main factor in controlling the fire and suppressed it. This study uses computer modeling and fire simulation technology of Pyrosim, FDS and smoke view to compare the difference between the performance of some traditional finishing materials like cement plastering, limestone and perforated yellow brick with the ACPs and their speed to transfer fire from floor to floor if used in multi storey buildings. The study highlighted that traditional finishing materials are more efficient than modern cladding materials and that the performance of ACP-PE is the worst among the materials examined by this study. Moreover, the cement plastering is the worst among the traditional local finishing materials.

Preliminary Study of Fire Spread in Cities and Forests, Using PMMA Specimen as a Fuel in CFD Simulations

2009 ◽  
Author(s):  
Koyu Satoh ◽  
Naian Liu ◽  
Qiong Liu ◽  
K. T. Yang
Keyword(s):  
Laboratory Experiment ◽  
Forest Fires ◽  
Three Dimensional ◽  
Fire Spread ◽  
Weather Data ◽  
Strong Wind ◽  
Cfd Simulations ◽  
Worst Case ◽  
Fire Propagation ◽  
Fire Spreading

It is important to examine the behavior of forest fires and city fires to mitigate the property damages and victims by fires. There have been many previous studies on forest fires where the fire spreading patterns were investigated, utilizing artificial satellite pictures of forest fires, together with the use of corresponding weather data and GIS data. On the other hand, large area city fires are very scarce in the world, particularly in modern cities where high-rise concrete buildings are constructed with sufficient open spaces. Thus, the examples of city fires to be referred are few and detailed investigations of city fires are limited. However, there have still been existing old cities where traditional houses built with flammable material such as wood, maybe historically important, only separated with very small open spacing. Fires may freely spread in those cities, once a big earthquake happens there and then water supply for the fire brigade is damaged in the worst case along with the effect of strong wind. There are some fundamental differences between the forest fires and city fires, as the fuel may distribute either continuously or discretely. For instance, in forest fires, the dead fallen leaves, dry grasses and trees are distributed continuously on the ground, while the wooden houses in cities are discretely distributed with some separation of open spacing, such as roads and gardens. Therefore, the wooden houses neighboring the burning houses with some separation are heated by radiation and flames to elevate the temperatures, thus causing the ignition, and finally reaching a large city fire. The authors have studied the forest fire spread and are planning to start a laboratory experiment of city fire spreading. In the preliminary investigation, a numerical study is made to correlate with the laboratory experiment of city fire propagation, utilizing the three-dimensional CFD simulations. Based on the detailed experimental analysis, the authors are attempting to modify the three dimensional CFD code to predict the forest fires and city fires more precisely, taking into account the thermal heating and ignition processes. In this study, some fundamental information on the city fire propagation has been obtained, particularly to know the safe open spacing distances between the houses in the cities and also the wind speed.

Experimental Study on Feasibility of New Scaffold Construction Scheme in Preventing Fire Spread

2013 ◽  
Vol 357-360 ◽  
pp. 415-420
Author(s):  
Yun Yang ◽  
Jun Jie He ◽  
Jun Tao Yang
Keyword(s):  
Experimental Study ◽  
Fire Risk ◽  
Fire Spread ◽  
Construction Scheme ◽  
New Type ◽  
Fire Spreading ◽  
Layer Steel ◽  
Fire Experiments

Aiming at the problem of fire risk of the traditional scaffold construction scheme, a new type of scaffold construction scheme was proposed. In the vertical layout of scaffold board, this scheme alternately arranged to take the "two layers of bamboo fence one layer steel fence". In order to verify the feasibility of the prevention of the spread of fire about the new scaffold construction scheme, three groups of fire experiments were designed. By the analysis of experimental phenomena and data results, it is concluded that the steel fence boards used as isolation layers in the new scaffold construction scheme can effectively mitigate the risk of fire spreading upward or downward along the burning scaffold.

scholarly journals Heat Emission from a Burning Cigarette

2001 ◽  
Vol 19 (5) ◽  
pp. 245-249
Author(s):  
K Miura ◽  
A Nagao ◽  
K Ueyama
Keyword(s):  
Heat Transfer ◽  
Heat Emission ◽  
Total Heat ◽  
Radiation Heat ◽  
Combustion Heat ◽  
Burn Rate ◽  
The Relationship

AbstractWe investigated the relationship between the smoldering burn rate and the heat transfer from a burning cigarette by measuring the heat emitted by radiation and convection, separately. The net heat generated and the net heat emitted by a burning cigarette did not vary with a change of the cigarette smoldering burn rate. The total heat emitted from a statically burning cigarette was about 50% of the total combustion heat. About 50% of the heat emitted was released as radiation heat. The smoldering burn rate did not affect the total amount of heat emitted nor the ratio of radiated heat to convected heat.

scholarly journals INVESTIGATION OF DESIGN PARAMETERS FACADE FIRE-FIGHTING EAVES FOR PREVENT THE SPREAD OF FIRES ON FACADE STRUCTURES OF HIGH-RISE BUILDINGS

Fire Safety ◽  
2021 ◽  
Vol 37 ◽  
pp. 16-23
Author(s):  
Ya. Ballo ◽  
R. Yakovchuk ◽  
V. Nizhnyk ◽  
O. Sizikov ◽  
A. Kuzyk
Keyword(s):  
Reference Conditions ◽  
Numerical Algorithms ◽  
Equation System ◽  
Fire Spread ◽  
Fire Fighting ◽  
Design Parameters ◽  
Fire Dynamics ◽  
High Rise ◽  
Building Facades ◽  
Fire Spreading

Purpose. The research based on FDS modeling aims to identify design parameters influence of the façade firefighting eaves at fire compartment border on the prevention of fire spreading in high-rise buildings.Methods. To calculate the temperature in high-rise building model Pyrosim computer system is used which serves as the user's shell application Fire Dynamics Simulator (FDS). This FDS system uses numerical algorithms to solve the complete Navier-Stokes differential equation system to determine the temperature and other hazardous factors during a fire.Results. This article deals with the results of using the FDS modeling to substantiate fire-fighting eaves design parameters, which are extended beyond the facade and are located at fire compartment border along the perimeter of high-rise buildings with a conventional height of more than 73.5 m. A comparative analysis of eaves' design parameters and their effect on the temperature distribution along the building facade during a possible fire was conducted. Comparative dependences of tempera-ture distribution on building facades were constructed, as well as their heating areas were determined.Scientific novelty. According to national and foreign regulations requirement analytical research and information sources on the of high-rise buildings design, fire safety requirements to the high-rise public buildings facades with a conventional height of more than 73.5 m were scientifically substantiated in terms of the requirements formation for limiting the fire spreading, smoke and building facades exterior constructions heating.Practical value. Obtained data was analyzed as a result of FDS modeling under the same reference conditions to provide a conclusion on facade fire-fighting eaves design parameters effectiveness at fire compartment border and further improvement ways of their construction and fire spread prevention in high-rise buildings.

Physical modelling of forest fire spreading through heterogeneous fuel beds

2011 ◽  
Vol 20 (5) ◽  
pp. 625 ◽  
Author(s):  
Albert Simeoni ◽  
Pierre Salinesi ◽  
Frédéric Morandini
Keyword(s):  
Field Experiments ◽  
Heterogeneous Medium ◽  
Reaction Diffusion ◽  
Physical Modelling ◽  
Fire Spread ◽  
Physical Models ◽  
Fire Intensity ◽  
Fire Behaviour ◽  
Fire Front ◽  
Fire Spreading

Vegetation cover is a heterogeneous medium composed of different kinds of fuels and non-combustible parts. Some properties of real fires arise from this heterogeneity. Creating heterogeneous fuel areas may be useful both in land management and in firefighting by reducing fire intensity and fire rate of spread. The spreading of a fire through a heterogeneous medium was studied with a two-dimensional reaction–diffusion physical model of fire spread. Randomly distributed combustible and non-combustible square elements constituted the heterogeneous fuel. Two main characteristics of the fire were directly computed by the model: the size of the zone influenced by the heat transferred from the fire front and the ignition condition of vegetation. The model was able to provide rate of fire spread, temperature distribution and energy transfers. The influence on the fire properties of the ratio between the amount of combustible elements and the total amount of elements was studied. The results provided the same critical fire behaviour as described in both percolation theory and laboratory experiments but the results were quantitatively different because the neighbourhood computed by the model varied in time and space with the geometry of the fire front. The simulations also qualitatively reproduced fire behaviour for heterogeneous fuel layers as observed in field experiments. This study shows that physical models can be used to study fire spreading through heterogeneous fuels, and some potential applications are proposed about the use of heterogeneity as a complementary tool for fuel management and firefighting.

Numerical and Experimental Study of Merging Fires in Square Arrays

2007 ◽  
Author(s):  
Kohyu Satoh ◽  
Liu Naian ◽  
Liu Qiong ◽  
K. T. Yang
Keyword(s):  
Heat Release ◽  
Heat Release Rate ◽  
Release Rate ◽  
Forest Fires ◽  
Large Scale ◽  
Gas Flow ◽  
Fire Spread ◽  
Total Heat ◽  
Total Heat Release ◽  
Convective Gas Flow

In large-scale forest fires and city fires, merging fires and fire whirls have often been observed, which cause substantial casualties and property damages. It is important to know particularly where and under what conditions of weather such merging fires and fire whirls appear in cities or forests. However, there have been no adequate answers, since the detailed physical characteristics about them are not fully clarified yet, although previous studies have examined the phenomena of merging flames. Therefore, we have carried out preliminary studies and found that the merged tall fires can enhance the fire spread, and developed a method to analyze burn-out data of fire arrays. If sufficient knowledge can be obtained by relevant experiments and numerical computations, it may be possible to mitigate the damages due to merged fires and fire whirls. The objective of this study is to investigate the merging conditions of fires in square arrays in laboratory experiments and also by CFD numerical simulations, varying the size of square array, inter-fire distance and heat release rate, to judge ‘unmerged’ or ‘merged’ conditions in the fire array. It has been found that the fire merging is dependent on the inter-fire distance in the array and also on the total heat release rate of all fires surrounding the center region of the array. Also found that the experimental and simulated results on the merged and unmerged cases in the fire array, as affected by the total heat release rate and the inter-fire distance, which control the convective gas flow into the array, behave very similarly. Therefore, it can be concluded that the fire merging in array fires are highly based on the convection in the flow field due to fires and can be predicted by simple CFD simulations.

scholarly journals Estimation of microbiological contamination of maize seeds using isothermal calorimetry

2020 ◽  
Vol 142 (2) ◽  
pp. 749-754
Author(s):  
Andrzej Skoczowski ◽  
Sebastian W. Przemieniecki ◽  
Jakub Oliwa ◽  
Monika Kula-Maximenko ◽  
Magdalena Rys ◽  
...  
Keyword(s):  
Heat Flow ◽  
Isothermal Calorimetry ◽  
Heat Emission ◽  
Total Heat ◽  
Raw Material ◽  
Microbiological Contamination ◽  
Maize Seeds ◽  
Number Of Microorganisms ◽  
Bacteria And Fungi ◽  
Isothermal Calorimeter

Abstract The storage of maize seed intended for industrial purposes in foil silo bags is associated with microbiological contamination of the material by bacteria and fungi. This results in the loss of a part of the raw material or its deterioration and causes financial losses. In this paper, the relationship between the number of microorganisms colonizing maize seeds as well as changes in heat flow has been proved. For this purpose, the heat flow and total metabolic heat emission values (total heat) were analyzed. Calorimetric measurements of seed samples were made using the TAM III isothermal calorimeter. The seed samples with the same heat flow curves shape were homogenized, and microbial DNA was isolated from them. The quantitative real-time polymerase chain reaction (qPCR) was performed for detecting the main group of microorganisms colonizing maize seeds. It has been shown that in the case of seeds less affected by Bacillus and fungi (including yeast), the heat flow (in the range of 0–360 min) has a falling shape, while for more infected it grows almost linearly. The more infected maize seeds also show significantly higher values of total heat emission. The described research can be used to quickly assess the degree of seed contamination.

Experimental analysis of fire spread across a two-dimensional ridge under wind conditions

2015 ◽  
Vol 24 (7) ◽  
pp. 1008 ◽  
Author(s):  
J. R. Raposo ◽  
S. Cabiddu ◽  
D. X. Viegas ◽  
M. Salis ◽  
J. Sharples
Keyword(s):  
Flow Velocity ◽  
Forest Fires ◽  
Experimental Analysis ◽  
Dynamic Effect ◽  
Fire Spread ◽  
Laboratory Scale ◽  
Lateral Spread ◽  
Two Dimensional ◽  
Vortex Strength ◽  
Fire Spreading

Results from a laboratory-scale investigation of a fire spreading on the windward face of a triangular-section hill of variable shape with wind perpendicular to the ridgeline are reported. They confirm previous observations that the fire enlarges its lateral spread after reaching the ridgeline, entering the leeward face with a much wider front. Reference fire spread velocities were measured and analysed, putting in evidence the importance of the dynamic effect due to flow velocity and its associated horizontal-axis separation vortex strength without dependence on hill geometry. Similar parameters estimated from three forest fires compared favourably with the laboratory-scale measurements.

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