| 1. |
- Fjellgaard Mikalsen, Ragni, et al.
(författare)
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Emerging Risks from Smoldering Fires : Results from the EMRIS project
- 2018
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Smoldering fires represent a severe, but often overlooked danger to society. Smoldering causes major economic losses for industrial facilities with production, transport and storage of biomass and biofuels worldwide. The smoke from post-flaming residual burning on the forest floor and in peatlands represents a major contributor to greenhouse gas emissions. [1]To prevent initiation of smoldering, and facilitate safe, efficient and complete extinguishment, a better fundamental understanding of smoldering is key. This is the aim of the research project EMRIS (Emerging Risks from Smoldering Fires). The consortium consists of 6 research institutes and universities in 5 countries, coordinated by Western Norway University of Applied Sciences in Haugesund, Norway. EMRIS started in 2015 and is now in its final stage. We will here present some points of interest from the project.Materials in the study include wood pellets, other biopellets, cotton, waste (wood chips), coal, wood fiber insulation and various pyrolysis products. Both experimental and modeling work has been done.Experimental work in small-scale has studied the sensitivity of smoldering ignition to a range of parameters [2], the impact of changes in air flow on the combustion [3], the effect of fire retardant content and fiber size [4], the transition from smoldering to flaming fire [5,6], early detection of smoldering [7]and heat extraction from the fuel bed with successfulextinguishment [8,9]. In medium scale experiments, initiationand propagation of reaction fronts have been studied [10]. TheEMRIS team also studies how particulate matter fromsmoldering fires can affect large scale phenomena, such ascloud formations, climate and public health.A cellular automaton model has been found to give a realistic representation of smoldering spread [11]. The method is based on a network of cells that mimic processes taking place in the material, which is easier to program and requires less computing power than traditional tools.The EMRIS project therefore represents progress within many different aspects of fire safety science. A continuation of the project is very much of interest, we welcome interested parties to discuss with us.
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| 2. |
- Fjellgaard Mikalsen, Ragni, et al.
(författare)
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Extinguishing smoldering fires in wood pellets through cooling
- 2017
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Extinguishing smoldering fires is a severe challenge for fire brigades, and has proven to be difficult even on the lab scale. In this study, the influence of a closed water cooling loop located within the fuel bed was investigated experimentally. Increasing the cooling led to a system less prone to intense combustion at an early stage, and eventually to complete extinguishment of self-sustained smoldering fires. Extinguishment was obtained in half of the cases with maximum cooling. Extinguishment occurred soon after smoldering had been established, giving a significant reduction in fuel consumption compared to the self-sustained smoldering fires that continued to complete burn-out.
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| 3. |
- Fjellgaard Mikalsen, Ragni, et al.
(författare)
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Extinguishing Smoldering Fires in Wood Pellets with Water Cooling : An Experimental Study
- 2019
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Ingår i: Fire technology. - : Springer Science and Business Media LLC. - 0015-2684 .- 1572-8099. ; 25:1, s. 257-284
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Tidskriftsartikel (refereegranskat)abstract
- Smoldering fires in stored or transported solid biofuels are very difficult to extinguish. The current study has explored heat extraction from the combustion zone as a method for extinguishing such flameless fires. Heat extraction from the sample was made feasible using water flowing through a metal pipe located inside the sample. The fuel container was a steel cylinder with insulated side walls, open at the top and heated from below. Wood pellets (1.25 kg, 1.8 l) was used as fuel. Results from small-scale experiments provide proof-of-concept of cooling as a new extinguishing method for smoldering fires. During self-sustained smoldering with heat production in the range 0 W to 60 W, the heat loss to the cooling unit was in the range 5 W to 20 W. There were only marginal differences between non-extinguished and extinguished cases. Up-scaling is discussed, cooling could be feasible for preventing smoldering fires in silos.
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| 4. |
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| 5. |
- Fjellgaard Mikalsen, Ragni, et al.
(författare)
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Smoldering combustion- from pulsations to extinguishment
- 2017
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Smoldering is known as a slow, but unpredictable form of combustion. In this study we have looked at how smoldering is affected by water cooling of the fuel bed without direct contact between fuel and water flow. The study is a part of the EMRIS project, and its findings have possible implications for preventing and suppressing fires in industrial storage units.
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| 6. |
- Karyaparambil, Dheeraj Dilip, et al.
(författare)
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Flame heights and charring on a particle board – An experimental study
- 2022
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Ingår i: Fire Safety Journal. - : Elsevier BV. - 0379-7112. ; 134
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Tidskriftsartikel (refereegranskat)abstract
- Vertically oriented particle-board samples were exposed to external venting flames to study the fire spread and charring behaviour along a timber façade. Variation in flame height and the height, volume, area, density, and depth of the char layer were studied to determine the impact of heat-release rate and experiment duration. There was a peak flame height after which the flame returned to steady height approximately equal to the value before the ignition of the particle board and flame heights with inert panels. Flames did not spread to the top of the panel with increased experiment duration. Char height and area were found to increase with heat-release rate but were not affected significantly by experiment duration. Char depth and volume increased with both experiment duration and heat-release rates. Char density decreased with increased experiment duration and heat-release rate.
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| 7. |
- Sesseng, Christian, et al.
(författare)
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Effect of particle granularity on smoldering fire in wood chips made from wood waste : An experimental study
- 2020
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Ingår i: Fire and Materials. - : John Wiley and Sons Ltd. - 0308-0501 .- 1099-1018. ; 44:4, s. 540-556
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Tidskriftsartikel (refereegranskat)abstract
- Fires in wood waste storages cause financial losses, are difficult to extinguish, and emit large amounts of fire effluents. The mechanisms related to fires in wood chip piles are not well elucidated. To find suitable preventive measures for handling such fires in wood waste, a better understanding of the physical properties of wood waste is needed. The present study investigates how granularity affects mechanisms of smoldering fire and transition to flaming in wood chip piles. Eighteen experiments with samples inside a top-ventilated, vertical cylinder were conducted. Heating from underneath the cylinder induced auto-ignition and smoldering fire, and temperatures and mass loss of the sample were measured. The results showed that granularity significantly affects the smoldering fire dynamics. Material containing larger wood chips (length 4-100 mm) demonstrated more irregular temperature development, higher temperatures, faster combustion, and higher mass losses than material of smaller wood chips (length <4 mm). The larger wood chips also underwent transition to flaming fires. Flaming fires were not observed for small wood chips, which instead demonstrated prolonged and steady smoldering propagation. The differences are assumed to be partly due to the different bulk densities of the samples of large and small wood chips affecting the ventilation conditions. Increased knowledge about these combustion processes and transition to flaming is vital to develop risk-reducing measures when storing wood chips made from wood waste in piles.
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