| 1. |
- Andersson, Petra, et al.
(författare)
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Experience a tunnel fire - live
- 2007
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Ingår i: BrandPosten. ; :36, s. 27-
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 2. |
- Andersson, Petra, et al.
(författare)
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Upplev brand i tunnlar live
- 2007
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Ingår i: BrandPosten. ; :36, s. 28-
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 3. |
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| 4. |
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| 5. |
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| 6. |
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| 7. |
- Arvidson, Magnus, et al.
(författare)
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Measurement of the efficiency of a water spray system against diesel oil pool and spray fires
- 2005
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Rapport (refereegranskat)abstract
- Simple and robust test methodologies that make it possible to measure and quantify the effectiveness of water spray or water mist systems intended for ‘large’ shipboard machinery spaces were investigated. Heat Release Rate calorimetry is usually the best method to measure the effectiveness of a water spray or mist system, although not all fire laboratories have access to such equipment. Therefore, there is a need to explore if other traditional measurement techniques can be used. Such methods include thermocouples, heat flux gages and Plate Thermometers. An additional method, the Pipe Thermometer, has been developed and investigated within the project. It consists of an insulated thin-walled stainless steel tube having an outer diameter of 103 mm with numerous thermocouples welded on the outside surface. The study, which was applied here on a water spray system, shows that the Pipe Thermometer is a possible method to use for evaluation of the efficiency of such system. It is definitely a better method than using heat flux meters or Plate Thermometer which were located at a distance from the fire source. The best correspondence between the measured data below the water spray system and the measured heat release rate was found between the measured gas temperature data and the measured convective heat release data. Consequently, there is no clear advantage of using the Pipe Thermometer (as mounted here) instead of traditional thermocouples at similar locations.
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| 8. |
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| 9. |
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| 10. |
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| 11. |
- Bjelland, Henrik, et al.
(författare)
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Tunnel fire safety management and systems thinking : Adapting engineering practice through regulations and education
- 2024
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Ingår i: Fire safety journal. - : Elsevier BV. - 0379-7112 .- 1873-7226. ; 146
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Tidskriftsartikel (refereegranskat)abstract
- Society is changing ever faster, and tunnels are complex systems where performance is affected by many different stakeholders. These conditions suggest that safety management needs to be proactive and based on a systems perspective that acknowledges socio-technical theories. Although systems thinking principles are foundational in overarching European regulations and goals, system principles generally don’t affect tunnel fire safety design principles or engineering practice. In the countries investigated in this study, tunnel fire safety management (TFSM) builds on experience-based and risk management-based principles that are optimized independently system by system. This is usually done with limited consideration of how these systems are interconnected and affect the overall tunnel system. The purpose of this paper is to investigate how systems thinking could support existing engineering practice. The work presented in this article is the outcome of a collaboration between fire safety researchers and practitioners from five countries and three continents. Through three workshops, current TFSM principles have been compiled and discussed. It is suggested that tunnel safety regulations be redesigned to strengthen the ability of engineers to work in design teams using systems thinking principles.
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| 12. |
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| 13. |
- Carvel, R., et al.
(författare)
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Fires in vehicle tunnels
- 2016
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Ingår i: SFPE Handbook of Fire Protection Engineering, Fifth Edition. - New York, NY : Springer. - 9781493925650 ; , s. 3303-3325
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Tunnel fire safety is a complex problem with no clear solution as yet. Current knowledge of vehicle fire behaviour in tunnels has been established on the basis of a relatively small selection of experimental fire tests, each of which is described. The characteristics of vehicle fires in tunnels are highlighted and issues to be considered when defining ‘design fire for tunnels are discussed. The mechanisms of fire spread in the tunnel environment are presented. The most common fire protection measures used in tunnels are ventilation systems, passive thermal barriers and, increasingly, water spray systems. Each of these three system types are discussed. © Society of Fire Protection Engineers 2016. All rights reserved.
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| 14. |
- Claesson, Alexander, et al.
(författare)
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Laboratory fire experiments with a 1/3 train carriage mockup
- 2012
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- A total of six fire tests were conducted in a mock-up of a subway carriage that is about 1/3 of a full wagon length. They were carried out under a large scale calorimeter in a laboratory environment. The aim of the tests was to investigate the initial fire growth in a corner scenario using different types of ignition sources that could lead to a flashover situation. The ignition sources used were either a wood crib placed on a corner seat or one liter of petrol poured on the corner seat and the neighboring floor together with a backpack. The amount of luggage and wood cribs in the neighborhood of the ignition source was continuously increased in order to identify the limits for flashover in the test-setup. The tests showed that the combustible boards on parts of the walls had a significant effect on the fire spread. In the cases where the initial fire did not exceed a range of 400 – 600 kW no flashover was observed. If the initial fire grew up to 700 – 900 kW a flashover was observed. The maximum heat release rate during a short flashover period for this test set-up was about 3.5 MW. The time to reach flashover was highly dependent on the ignition type, wood cribs or backpack and petrol.
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| 15. |
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| 16. |
- Fan, Chuan Gang, et al.
(författare)
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Effect of tunnel cross section on gas temperatures and heat fluxes in case of large heat release rate
- 2016
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Ingår i: Applied Thermal Engineering. - : Elsevier. - 1359-4311 .- 1873-5606. ; 93, s. 405-415
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Tidskriftsartikel (refereegranskat)abstract
- Tests with liquid and solid fuels in model tunnels (1:20) were performed and analysed in order to study the effect of tunnel cross section (width and height) together with ventilation velocity on ceiling gas temperatures and heat fluxes. The model tunnel was 10m long with varying width (0.3m, 0.45m and 0.6m) and height (0.25m and 0.4m). Test results show that the maximum temperature under the ceiling is a weak function of heat release rate (HRR) and ventilation velocity for cases with HRR more than 100MW at full scale. It clearly varies with the tunnel height and is a weak function of the tunnel width. With a lower tunnel height, the ceiling is closer to the base of continuous flame zone and the temperatures become higher. Overall, the gas temperature beneath the ceiling decreases with the increasing tunnel dimensions, and increases with the increasing longitudinal ventilation velocity. The HRR is also an important factor that influences the decay rate of excess gas temperature, and a dimensionless HRR integrating HRR and other two key parameters, tunnel cross-sectional area and distance between fuel centre and tunnel ceiling, was introduced to account for the effect. An equation for the decay rate of excess gas temperature, considering both the tunnel dimensions and HRR, was developed. Moreover, a larger tunnel cross-sectional area will lead to a smaller heat flux.
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| 17. |
- Fan, Chuan Gang, et al.
(författare)
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Experimental study of sidewall effect on flame characteristics of heptane pool fires with different aspect ratios and orientations in a channel
- 2017
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Ingår i: Proceedings of the Combustion Institute. - : Elsevier BV. - 1540-7489 .- 1873-2704. ; 36:2, s. 3121-3129
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Tidskriftsartikel (refereegranskat)abstract
- A series of small scale tests was conducted to investigate the influence of sidewall on flame characteristics of heptane pool fires in a channel, considering pool shape (aspect ratio: 1, 2, 4 and 8) and pool orientation relative to sidewall. Distance between fire and sidewall was changed systematically. Both transverse flame development (along the direction of channel width) and longitudinal flame development (along the direction of channel length) were recorded by digital video. Results show that for a fixed fire location, the heat release rate increases with the increasing pool aspect ratio (namely a larger pool perimeter), which indicates more air entrainment and more intense combustion. In wall fire cases, when the long pool rim is perpendicular with channel sidewall, the flame can obtain more air entrainment with a weaker boundary restriction from the sidewall, compared to the case with the long pool rim being parallel with sidewall. Comparison of some previously established correlations based on various experimental conditions with our test results is made. Due to the fact without considering sidewall effect and fuel shape on the air entrainment of fire plume, the classic correlations need to be further improved. Therefore, an integral flame length model considering both sidewall effect and fuel shape is developed, which correlates well with all the data from cases with various pool positions, orientations and aspect ratios. © 2016 The Combustion Institute. Published by Elsevier Inc.
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| 18. |
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| 19. |
- Fridolf, Karl, et al.
(författare)
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Full Scale Tunnel Evacuation Experiment to Determine Appropriate Emergency Exit Portal Designs in Road Tunnels
- 2016
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Ingår i: Proceedings from the Seventh International Symposium on Tunnel Safety and Security. - 9789188349118 ; , s. 441-452
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In this paper, the execution and results of an evacuation experiment that was conducted in a road tunnel in Stockholm in 2014 is presented. The primary objective of the experiment was to evaluate the effectiveness of different emergency exit portal designs, and other technical installations/aids in the tunnel, during a fire evacuation in smoke. Based on the results, it is concluded that the emergency exit portal design, which was developed and evaluated prior to the experiment, seems appropriate for the intended use. However, in order to increase the portal may be complemented with information signs on the wall opposite to the exit, way-finding signs including distances to the closest emergency exits on both tunnel walls, and a loudspeaker installation that can inform evacuating people about the location of the available exits.
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| 20. |
- Fridolf, Karl, et al.
(författare)
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Taking advantage of theories and models on human behaviour in the fire safety design of underground transportation systems
- 2012
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Ingår i: [Host publication title missing]. - 0284-5172. - 9789187017261 ; , s. 619-626
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Konferensbidrag (refereegranskat)abstract
- Fire accidents in underground transportation systems, e.g., tunnels and underground stations, can cause many fatalities. It is therefore important in fire safety design to give adequate consideration to all aspects related to evacuation. The paper provides a review of two previously reported fire accidents based on a theoretical framework, namely four accepted human behaviour theories. These theories provide qualitative guidance on human behaviour in the event of fire in underground transportation systems, and it is therefore argued that they need to be considered in the fire safety design of these facilities.
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| 21. |
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| 22. |
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| 23. |
- Gehandler, Jonatan, et al.
(författare)
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Performance-based design of road tunnel fire safety : Proposal of new Swedish framework
- 2014
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Ingår i: Case Studies in Fire Safety. - : Elsevier Ltd. - 2214-398X. ; 1:1, s. 18-28
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Tidskriftsartikel (refereegranskat)abstract
- This paper contains a proposal of new Swedish framework for performance-based design of road tunnel fire safety derived from Swedish and European regulation. The overall purpose of the guideline is to protect life, health, property, environment, and key societal functions from fire. The guideline is structured into five key groups of requirements: #1 Proper management and organisation, #2 to limit the generation and spread of fire and smoke, #3 to provide means for safe self-evacuation, #4 to provide means and safety for the rescue service, and #5 to ensure load-bearing capacity of the construction. Each group contains a hybrid of prescriptive requirements, performance-based requirements, and acceptable solutions. Prescriptive requirements must be fulfilled, however, it is the choice of the design team to either adopt the proposed acceptable solutions, or to design alternative solutions by verifying that performance-based requirements are satisfied. For verification of performance-based requirements through risk analysis the operational, epistemic, and aleatory uncertainties are considerable. Therefore, a scenario-based risk analysis with several specified input variables and methods is recommended for verification of #3 and #5. Indispensable complements are scenario exercises, emergency exercises and similar methods that validate the design and highlight organisational aspects. The proposed design guide has been developed by the authors together with the advisory group established for the work.
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| 24. |
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| 25. |
- Gehandler, Jonatan, et al.
(författare)
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Principer och strategier för ventilation vid brand i undermarksanläggningar
- 2018
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The report describes different underground systems including mines and tunnels during construction (tunneling). The key factors that affect fire development in underground systems are described. Proposal and recommendations for ventilation strategies in case of fire are given. The report covers both fuel- and ventilation-controlled fires. In general, a minimal ventilation limits the fire growth and may even inert the fire through ascended smoke. A minimal ventilation also contributes to improved conditions for a first fire extinguishing attempt and evacuation.
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| 26. |
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| 27. |
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| 28. |
- Guo, Qinghua, et al.
(författare)
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Numerical study on thermally driven smoke flow characteristics in long tunnels under natural ventilation
- 2023
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Ingår i: International journal of thermal sciences. - : Elsevier Masson s.r.l.. - 1290-0729 .- 1778-4166. ; 192
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Tidskriftsartikel (refereegranskat)abstract
- The paper focuses on the flow structures and mass flow rates of thermally driven smoke flows induced by fires in long transportation tunnels under natural ventilation. The important influencing factors including heat release rate (HRR), tunnel width and height, are taken into consideration. The mechanism of the smoke flow movement is explored. The results show that for a fire in a long naturally ventilated transportation tunnel, there exists a critical point which is dependent on HRR and tunnel geometry. This critical point is defined as the location where the smoke layer thickness and the outgoing mass flow rate increase towards it and decrease after it. Further, it is found that the critical point moves farther away from the fire source in a wider or higher tunnel, while it lies closer to the fire source for a higher HRR. A correlation is proposed to estimate the location of the critical point. The outgoing mass flow rates along the tunnel are calculated using the two-layer flow model and well-mixed flow model of thermally driven flows, and the results indicate that these models produce satisfactory predictions of the mass flow rates if the vertical temperature profile is known. © 2023 The Authors
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| 29. |
- Guo, Qinghua, et al.
(författare)
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Study on spilled liquid from a continuous leakage in sloped tunnels
- 2022
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Ingår i: Tunnelling and Underground Space Technology. - : Elsevier Ltd. - 0886-7798 .- 1878-4364. ; 120
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Tidskriftsartikel (refereegranskat)abstract
- The study focuses on the behaviors of spilled liquid from a continuously leaked tank in sloped tunnels. Spillage width and area, which impact the potential heat release rates in case of fire, are investigated under different tunnel slopes and leakage flow rates by numerical simulations using interFoam based on the VOF method in the OpenFOAM toolbox following the validation. The simulation results show that the spillage width initially decreases rapidly and then slowly as the tunnel slope increases. Other parameters, including road surface roughness, physical properties of liquid and leakage source height, are also considered. Empirical models for predicting the spillage width and area are established considering both tunnel slope and leakage flow rate. The results may provide guidance for tunnel safety design and drainage system design affiliated with a tank leakage inside a tunnel. © 2021 The Author(s)
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| 30. |
- Guo, Qinghua, et al.
(författare)
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Theoretical and numerical study on mass flow rates of smoke exhausted from short vertical shafts in naturally ventilated urban road tunnel fires
- 2021
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Ingår i: Tunnelling and Underground Space Technology. - : Elsevier Ltd. - 0886-7798 .- 1878-4364.
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Tidskriftsartikel (refereegranskat)abstract
- The study focuses on the mass flow rate of the buoyancy-driven gases exhausted from the shaft in naturally ventilated urban road tunnel fires. Theoretical analyses and numerical simulations are performed. The model to predict the mass flow rate of the incoming smoke exhausted by the nearest shaft is developed by considering that the smoke is exhausted along the four sides of the shaft separately. Based on the heat balance between the incoming smoke exhausted and the total gas flow exhausted, the model to estimate the total mass flow rate exhausted from the shaft (both smoke and entrained air) is also established. Meanwhile, a series of numerical simulation in a naturally ventilated tunnel considering the heat release rate (HRR), the shaft height, shaft length and width, shaft location was carried out. The simulation results show that the shaft height has a limited contribution to the mass flow rate of the incoming smoke exhausted while a larger shaft cross-sectional area shows a favorable performance in exhausting the smoke. Further, the air entrainment into the shaft increases with both the shaft height and shaft cross-sectional area. Comparisons of the mass flow rates of the incoming smoke and the total mass flow rates exhausted between simple calculations and simulations are made, showing that the simple models perform well. Further, it is found that there exist two regimes for the total mass flow rate corresponding to different smoke modes in the shaft (complete plug-holing, plug-holing and without plug-holing), which is caused by the different driven forces in the shaft. The outcomes of this work could provide some guidance for the design of vertical shaft and smoke control in naturally ventilated tunnel in urban area.
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| 31. |
- Guo, Qinghua, et al.
(författare)
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Theoretical studies on buoyancy-driven ceiling jets of tunnel fires with natural ventilation
- 2020
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Ingår i: Fire safety journal. - : Elsevier Ltd. - 0379-7112 .- 1873-7226. ; 119
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Tidskriftsartikel (refereegranskat)abstract
- The paper presents a theoretical study on the ceiling jets induced by small fires in tunnels. The ceiling jet thickness, temperature rise and velocity are analyzed theoretically with Non-Boussinesq approximation. The study focuses on the radial and one-dimensional ceiling jets. Numerical solutions in the radial region and one-dimensional shooting region are obtained and new analytical solutions in the critical flow region are achieved. Analytical solutions indicate that the ceiling jet thickness increases with distance away from the fire source, which largely differs from the existing models implying that the ceiling jet thickness in the one-dimensional critical flow remains constant. Additionally, impacts of the air entrainment, friction and heat transfer on the ceiling jet are analyzed. It is found that in the radial and one-dimensional shooting flow regions, the air entrainment has a much more significant effect than the friction and heat transfer. However, in the one-dimensional critical flow region, the impact of air entrainment seems to be negligible and the flow is dominated by the friction and heat transfer. Further, validation of the present theory is made by comparing with previous theories, semi-empirical models, and experiments. The results show that the present theory provides a good prediction of the ceiling jet properties with natural ventilation for a small fire. © 2020 The Authors
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| 32. |
- Hansen, Rickard, 1968-, et al.
(författare)
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An Engineering tool to calculate heat release rates of multiple objects in underground structures
- 2011
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Ingår i: Fire safety journal. - : Elsevier BV. - 0379-7112 .- 1873-7226. ; 46:4, s. 194-203
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Tidskriftsartikel (refereegranskat)abstract
- Simple theoretical calculations of the overall heat release rate (HRR) of multiple objects have been carried out. The results were compared to fire experiments in a model tunnel using wood cribs placed at equal distance from each other. Three different methods are presented which are based on physical relations for fire spread between the wood cribs. The first method uses a critical heat flux as ignition criteria while the other two methods use an ignition temperature. The method using the critical heat flux as ignition criteria shows very good agreement with the corresponding experimental results used. The two methods using the ignition temperature as ignition criteria did not agree well with the corresponding experimental results. The prerequisites, that the methods should be kept relatively simple to be of practical use and that the burning objects should not necessarily have to be of uniform composition, were fulfilled.
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| 33. |
- Hansen, Rickard, 1968-
(författare)
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Design fires in underground hard rock mines
- 2011
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- During several decades considerable research activities have been conducted with respect to fires in coal mines, but the research activities with respect to hard rock mines have been limited. As the hard rock mines are getting more complex the need for deeper understanding of fires in underground hard rock mines are getting more in demand. The more urgent demands are the need for more specific heat release rate curves as design fires, applicable fire experiments and any method that would allow for the calculation of the total heat release rate curve of an object. This thesis presents a number of examples on design fire curves applicable to underground hard rock mines; it also presents the results of model scale fire experiments and methods for calculating the total heat release rate of several objects at uniform as well as non-uniform conditions. Tests were carried out in a model scale tunnel using wooden pallets as fire load. The parameters tested were the distance between piles of pallets and longitudinal ventilation rate. It was found that an increasing ventilation rate also increases the peak heat release rate. When studying the curves of heat release rates it was found that when the distance between the ignited pile and the second pile increased to a certain level the delayed ignition of the second pile will result in that the peak heat release rate of the adjacent piles will not occur simultaneously. The ignition data indicated that the ignition time of adjacent piles decreased as the longitudinal ventilation increased. A method using a critical heat flux as ignition criterion exhibited very good agreement with the corresponding experiments for both uniform as well as non-uniform conditions. The methods using the ignition temperature as ignition criterion did not agree very well with any of the corresponding experiments.
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| 34. |
- Hansen, Rickard, et al.
(författare)
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Full-scale fire experiments with mining vehicles in an underground mine
- 2013
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This report comprises two full scale fire experiments in a mine drift in Sala, Sweden,involving a loader and a drilling rig respectively.It was found in the experiment involving the loader that the front part of the vehiclenever ignited. The maximum measured heat fluxes at the front tyres were found tonever exceed the critical heat flux of natural rubber and thus ignition never occurred.Furthermore, the maximum temperature recorded at the hydraulic hoses in the waistwas 381 K, thus the low temperatures did not allow for further fire spread. The maximumheat release rate from the experiment was 15.9 MW and it was attained approximately 11 minutes after ignition. The resulting heat release rate curve of the wheel loaderfire displays a fire that is dominated by initially the sudden increase when primarily the first tyre is engulfed by flames and then by the slowly declining heat release ratesof the large tyres of the vehicle. Still, the stop of fire spread from the waist and forward clearly shortened the duration of the fire considerably.It was found in the experiment with the drilling rig that the entire vehicle had participated in the fire and the combustible material had been consumed – except for the hydraulic hoses approximately two meters in front of the cab and forward, some amount of hydraulic oil and most of the low voltage cable on the cable reel. The maximum heatrelease rate from the experiment was 29.4 MW and it was attained after 21 minutes. The resulting heat release rate curve of the drilling rig displays a fire with high heat release rates and relatively short lived.
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| 35. |
- Hansen, Rickard, et al.
(författare)
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Heat release rate measurements of burning mining vehicles in an underground mine
- 2013
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Ingår i: Fire safety journal. - : Elsevier BV. - 0379-7112 .- 1873-7226. ; 61, s. 12-25
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Tidskriftsartikel (refereegranskat)abstract
- Heat release rates from two full-scale fire experiments with mining vehicles in an underground mine are presented. The mining vehicles involved were a wheel loader and a drilling rig typical for mining operations. The calculated peak heat release rate of the loader was 15.9 MW and occurred after approximately 11 min from ignition. The calculated peak heat release rate of the drilling rig was 29.4 MW and occurred after approximately 21 min from ignition. The heat release rate was calculated from measured data of gas concentrations of oxygen, carbon monoxide and carbon dioxide, measured gas velocity and measured gas temperatures. The fuel load of the wheel loader consisted mainly of the tyres, the hydraulic oil and the diesel fuel. The fuel load of the drilling rig consisted mainly of the hydraulic oil and the hydraulic hoses. The calculated heat release rate curves were controlled by comparing the summed up energy contents of the participating components with the integrated heat release rate curves. © 2013 Elsevier Ltd.
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| 36. |
- Hansen, Rickard, 1968-, et al.
(författare)
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Heat release rates of multiple objects at varying distances
- 2012
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Ingår i: Fire safety journal. - : Elsevier BV. - 0379-7112 .- 1873-7226. ; 52:Aug, s. 1-10
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Tidskriftsartikel (refereegranskat)abstract
- This paper describes simple theoretical calculations of the overall heat release rate (HRR) of multiple objects at both constant and varying distances that have been carried out. The results were compared to both fire experiments in a longitudinal ventilated model tunnel (scale 1:15) using piles of wooden pallets placed at varying distance from each other and with model scale fire experiments (scale 1:4) conducted with piles of wooden pallets in the open. Two different methods are presented which are based on physical relations for fire spread between the piles of wooden pallets. The first method uses a critical heat flux as ignition criteria while the other method uses an ignition temperature. The method using the critical heat flux as ignition criteria shows very good agreement with the corresponding experimental results used. The method using the ignition temperature as ignition criteria did not agree well with the corresponding experimental results. The prerequisite that the burning objects should not necessarily have to be positioned at equal distances was fulfilled. The results can be used to estimate the heat release rate in full scale tunnel experiments where wooden pallets have been used as fuel.
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| 37. |
- Hansen, Rickard, et al.
(författare)
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Model scale fire experiments in a model tunnel with wooden pallets at varying distances
- 2010
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This report is part of the research project “Concept for fire and smoke spread prevention in mines”, conducted by a research group at Mälardalen University. The project is aimed at improving fire safety in mines in order to obtain a safer working environment for the people working for the mining companies in Sweden or for visitors in mines open to the public. This report comprises a number of model scale fire experiments conducted in a model tunnel at SP facilities in Borås, Sweden. The main purposes of the report are: - Obtain data which can validate models to calculate the total heat release rate of multiple objects - To investigate the influence on the heat release rate curve that a varying distance between the fuel objects will have. - To investigate the influence on the heat release rate, fire growth rate and time to ignition for adjacent fuel objects. The effects of ventilation are taken into account in the model.. The work in this report started with describing the theoretical basis of scaling theory and the determination of heat release rate at fire experiments, continuing with describing the experimental setup with the fuel load and instrumentation used. After that the experimental procedure and the experimental results were described and analysed. The results from the experiments were thereafter discussed and finally conclusions were drawn. The findings and conclusions of the study were as following: It was found that an increasing ventilation rate slightly increases the maximum heat release rate, which is in accordance with earlier research. The ventilation rate will have an influence on the fire growth rate. In the tests with the highest ventilation rate, a slower fire growth rate was displayed compared to the other two cases. This could possibly be explained by the fact that the height of the pile of wooden pallets (205 mm) was practically equal to the short side of the pile (200 mm) and the fire was started on the long side, thus as the longitudinal ventilation is increased less fuel area is exposed to the tilted flames resulting in that less parts take place in the combustion during the growth phase and thus the fire growth rate decreases. When studying the graphs of the various heat release rates it was found that when the distance between pile #1 and pile #2 increased to a certain level the ignition of pile #2 will be delayed resulting in that not all piles are burned with their maximum heat release rate at the same time. The delay in ignition of adjacent pallet can be distinguished by a “hump” before the peak value in the heat release rate curves. In cases with short distances between the piles the ignition of 3 adjacent piles took place almost simultaneously and resulting in a total heat release curve where the pallet piles burn at their maximum at nearly the same time, i.e. the effects of the delay of ignition is not really showing up in the time to reach maximum heat release rate. It was also found that the peak value of the heat release rate decreases as the distances between the piles are increased – from ~500 kW down to ~450 kW – as the curve is stretched out in time. The ignition data indicated that the time to ignition of adjacent piles would decrease as the longitudinal ventilation was increased. Further validation work should take place with respect to validating the experimental data with output data from theoretical models. Further studies and experiments should take place that vary additional parameters besides the distance between the individual fuel objects. This in order to make further comparisons with calculation models to predict the total heat release rates of complex objects, such as for example a vehicle.
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| 38. |
- Hansen, Rickard, 1968-
(författare)
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Study of heat release rates of mining vehicles in underground hard rock mines
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A unique study on fire safety in hard rock underground mines with focus on heat release rates of mining vehicles is presented. A literature inventory was conducted with respect to fires in underground hard rock mines, which revealed that the most common fire cause in underground mines was flammable liquid sprayed onto hot surface and the most common fire object was a vehicle. A major concern was the lack of documented fire experiments in mining vehicles and heat release rate curves. It also revealed the limited research carried out on fire safety and fire development on vehicles found in hard rock underground mines.In order to fill the gap of knowledge lack on heat release rates, fire experiments were carried out on wood cribs and wooden pallets in a model-scale tunnel with longitudinal ventilation where the distance between the fuel items were kept constant as well as varied. Different ignition criteria were applied in the ensuing calculations. It was found that the critical heat flux criterion generally showed very good agreement with the corresponding results of performed fire experiments but tended to have too short ignition times when the distance between the fuel items was increased. The ignition temperature criterion generally performed poorly compared with the measured results, but it was found that the accuracy improved considerably as the distance between the fuel items and the amount of energy accumulated on the fuel surface was increased.As a final approach, two full-scale fire experiments were carried out in an operative underground mine using a wheel loader and a drilling rig respectively. The resulting heat release rates of the experiments were compared with calculated overall heat release rates applying the different ignition criteria. It was found that the critical heat flux criterion resulted in ignition times very close to the observed ignition times. The ignition temperature criterion resulted in surface temperatures that never achieved the corresponding ignition temperatures. Some difficulties were experienced when calculating the heat release rate curve of the wheel loader, as it was difficult to accurately predict the mechanical failure of a significant part initiating the highly significant fire in the hydraulic oil. Additional heat terms were added to the heat balance, where the added flame radiation term was found to have a large impact on the output results while the heat loss terms were found to have very little effect.
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| 39. |
- He, Kun, et al.
(författare)
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Experimental study on flame characteristics of double fires in a naturally ventilated tunnel : Flame merging, flame tilt angle and flame height
- 2021
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Ingår i: Tunnelling and Underground Space Technology. - : Elsevier Ltd. - 0886-7798 .- 1878-4364. ; 114
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Tidskriftsartikel (refereegranskat)abstract
- A series of fire tests was carried out to investigate the diffusion flame characteristics of double fires generated from separated burners in a naturally ventilated tunnel, considering different heat release rates and fire separation distances. The results show that the flame tilt angle, as well as the horizontal projected flame length, first increases with fire separation distance and then remains constant, but the vertical flame length first decreases and then remains constant, which is different from two fires in free spaces where flames do not tilt when the separation distance is relatively long. This difference is caused by the non-dimensional fire induced air flow velocity in the tunnel, which is mainly related to the tunnel cross-section dimensions and burner radius. Three regions can be identified, i.e. flame vertical merging, plume vertical merging and non-merging with flame tilted. The critical flame merging separation distance, estimated by the flame merging probability, is greater than that of two fires in an open environment due to the fire-induced air flows. The merging flame height is lower than that of a single fire with a same heat release rate. A correlation was proposed to estimate flame height of two fires in a tunnel by the modified non-dimensional heat release rate using an air entrainment perimeter as the characteristic length. This work enhances the understanding of diffusion flame behaviors of double fires in naturally ventilated tunnels.
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| 40. |
- He, Kun, et al.
(författare)
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Experimental study on the maximum ceiling gas temperature driven by double fires in a tunnel with natural ventilation
- 2024
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Ingår i: Tunnelling and Underground Space Technology. - : Elsevier Ltd. - 0886-7798 .- 1878-4364. ; 144
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Tidskriftsartikel (refereegranskat)abstract
- The maximum gas temperature below the ceiling is an important parameter for tunnel safety. The present study analyzed the characteristics of the maximum excess ceiling gas temperature driven by double fire sources in a naturally ventilated tunnel. A series of small-scale tunnel fire experiments were carried out with different fire separation distances and heat release rates. Theoretical analysis based on the equivalent virtual origin was also performed. The results showed that there exists only one peak gas temperature when the two fire plumes are merged before reaching the ceiling, while two peak gas temperatures can be observed when the two fire plumes are completely separated. The maximum excess gas temperature below the tunnel ceiling gradually decreases with an increasing fire separation distance in the plume merging region (S < Scp). When the fire separation distance increases further (S > Scp), the effect of the fire separation distance on the maximum gas temperature below the ceiling is very limited. Furthermore, a model using an equivalent fire source was proposed to predict the maximum excess gas temperature below the ceiling, considering different plume merging states. The present study contributes to the understanding of the maximum excess gas temperature characteristics of the smoke flow driven by double fires with an equal heat release rate in naturally ventilated tunnels.
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| 41. |
- He, Kun, et al.
(författare)
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Fire spread among multiple vehicles in tunnels using longitudinal ventilation
- 2023
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Ingår i: Tunnelling and Underground Space Technology. - : Elsevier. - 0886-7798 .- 1878-4364. ; 133
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Tidskriftsartikel (refereegranskat)abstract
- The characteristics of fire spread among multiple vehicles in tunnels using longitudinal ventilation were investigated by analyzing the experimental data from a series of fire tests in a 1:15 scale tunnel. Further, a simple theoretical model for gas temperature in a tunnel with multiple fire sources was proposed and used in analysis of the experimental data. The results showed that, for objects (wood piles) placed at a same separating distance downstream of the fire, the fire spread occurred faster and faster along the tunnel. Validation of the simplified temperature model for multiple fire sources was made against both model and full-scale tunnel fire tests. The model was further used to predict the critical conditions for fire spread to the second and third objects. Comparisons with the test data showed that average excess temperature of 465 K (or an equivalent incident heat flux of 18.7 kW/m2) could be used as the criterion for fire spread, and this was verified further by other model-scale tests and full-scale tests. The results showed that the critical fire spread distance monotonously increases with the heat release rate, and decreases with the tunnel perimeter. For multiple fire sources with equivalent heat release rates, as the separation distance between the first two fire sources increases, the critical fire spread distance from the second fire source to the third fire source decreases, but the total fire spread distance from the first fire source to the third one increases. If the total heat release rate at the site of a downstream fire source is greater than that at the former fire source, the critical fire spread distance becomes longer.
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| 42. |
- Husted, Bjarne Paulsen, et al.
(författare)
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Verification, validation and evaluation of FireFOAM as a tool for performance based design
- 2018
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The open source CFD code FireFOAM has been verified and validated against analytical solution and real fire tests. The verification showed that FireFOAM solves the three modes of heat transfer appropriately. The validation against real fire tests yielded reasonable results. FireFOAM has not been validated for a large set of real fires, which is the case for FDS. Therefore, it is the responsibility of the user to perform the validation, before using the code.One of the advantages of FireFOAM compared to the Fire Dynamic Simulator is that FireFOAM can use unstructured grid.FireFOAM is parallelised and scales reasonable well, but is in general considerably slower in computation speed than the Fire Dynamic Simulator. Further, the software is poorly documented and has a steep learning curve. At present it is more a tool for researchers than for fire consultants.
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| 43. |
- Ingason, Haukur, et al.
(författare)
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3 MW from a single tyre
- 2008
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Ingår i: BrandPosten. ; :39, s. 6-
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 44. |
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| 45. |
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| 46. |
- Ingason, Haukur, et al.
(författare)
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A New Methodology of Design Fires for Train Carriages Based on Exponential Curve Method
- 2016
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Ingår i: Fire technology. - : Springer Science and Business Media LLC. - 0015-2684 .- 1572-8099. ; 52:5, s. 1449-1464
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Tidskriftsartikel (refereegranskat)abstract
- Design fires have great influences on the fire safety concepts and safety measures, and are the basis for any assessment and calculation in tunnel fire safety design. A new methodology of design fires for individual train carriages is proposed based on the exponential design fire curve method and state-of-the-art fire research. The three key parameters required for construction of a design fire are the maximum heat release rate, time to maximum heat release rate, and energy content. An overview of the full scale train carriage fire tests is given and the results show that the maximum heat release rate is in a range of 7 MW to 77 MW and the time to reach the maximum heat release rate varies from 7 min to 118 min. The method could be employed to one single train carriage or several carriages, and alternatively one carriage could be divided into several individual sections. To illustrate the use of the methodology, several engineering applications are presented, including design fires for a metro train carriage with a maximum heat release rate of 77 MW, a double-deck railway train carriage with a maximum heat release rate of 60 MW and a tram carriage with a maximum heat release rate of 28 MW. The main objective is to provide practicing engineers with a flexible and reliable methodology to make design fires for individual train carriages in performance-based tunnel fire safety design.
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| 47. |
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| 48. |
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| 49. |
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