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  • 1.
    Andersson, Petra
    et al.
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Byström, Alexandra
    Luleå University of Technology, Sweden.
    Fjellgaard Mikalsen, Ragni
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge.
    Försth, Michael
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Van Hees, Patrick
    Lund University, Sweden.
    Kovacs, Peter
    RISE - Research Institutes of Sweden, Samhällsbyggnad, Energi och cirkulär ekonomi.
    Runefors, Marcus
    Lund University, Sweden.
    Innovativa elsystem i byggnader: konsekvenser för brandsäkerhet2019Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Det sker en snabb teknikutveckling i den elektriska miljön i byggnader, framförallt i våra bostäder. Ett exempel är lokal produktion av el, där solcellsinstallationer blir alltmer populära. Sådan elproduktion medför även förändringar i övriga delar av byggnaders elektriska infrastruktur, såsom DC-nät och i vissa fall energilagring i batterisystem. Utvecklingen sker till stor del som ett svar på behovet av mer hållbara lösningar, ur ett växthuseffektperspektiv, för vår elförsörjning, och förstärks bland annat av statligt stöd och ökad tillgänglighet på marknaden.Ny elektrisk teknologi kan leda till ökad brandrisk och denna förstudie har haft som mål att undersöka denna problematik. Metoden har varit workshops med intressenter och experter inom området, intervjuer, samt litteraturstudier.Av de studerade områdena förefaller solcellsanläggningar skapa störst utmaningar i framtiden om inget görs. Detta beror dels på bristfälligt regelverk men även på att dessa system är distribuerade i byggnaderna med flera delar som kan orsaka brand och att delar är exponerade för utomhusklimat vilket får stora konsekvenser vad gäller uppkomst av fel.Brandsäkerheten i samhället har sett ur ett långt tidsperspektiv väsentligt förbättrats. Detta har huvudsakligen drivits fram med hjälp av ett förbättrat regelverk, som ofta inkluderat förbättrade provnings- och kvalificeringsmetoder. En generell observation i detta projekt är att regelverket inte hinner utvecklas i samma takt som tekniken. Detta är en ofta återkommande utmaning inom brandsäkerhet, men gäller speciellt för de teknikområden som behandlas i denna rapport där utvecklingen går mycket snabbt, och de ingående komponenterna nästan uteslutande har stor inneboende brandpotential. Rapporten konstaterar att för att skapa ett relevant regelverk behövs tillämpad forskning, så kallad prenormativ forskning, inom prioriterade områden för att besvara de frågor som ställs vid formulerandet av nya regler och standarder. Exempel på områden som bör prioriteras är 1) komplettering av det än så länge magra statistiska underlaget för bränder i solcellsinstallationer med olycksutredningar, och studier av redan befintliga olycksutredningar, 2) studier av branddynamiken i solcellsinstallationer, såväl byggnadsapplicerade som integrerade, och såväl tak- som fasadmonterade sådana, 3) studier av ljusbågars uppkomst och hur dessa kan undvikas, alternativt hur det kan undvikas att de ger upphov till bränder, 4) skapa underlag för säker installation av batterilager, samt 5) kvalitetssäkring av så kallade second-life batterier, dvs. begagnade batterier, som används i batterilager.

  • 2.
    Eidissen Jensen, Ulla
    et al.
    NTNU Norwegian University of Science and Technology, Norway.
    Fjellgaard Mikalsen, Ragni
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge. Western Norway University of Applied Sciences, Norway .
    Steen-Hansen, Anne
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge.
    The effect of fire retardants on smouldering fires in loose fill wood fibre building insulation2017Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Building insulation products produced from renewable biomass is becoming increasingly common in buildings due to environmental lifecycle requirements. Biomass insulation products are combustible and can contribute to fires through flaming and smouldering combustion. Incidents have been reported where insufficient spacing between combustible insulation and heat-producing electrical appliances has led to smouldering and subsequent development of flaming fires. Insulation materials often contain fire retardants, though their performance with regard to smouldering fire is not well understood. [1, 2] This study investigates the temperature exposure needed to initiate self-sustaining smouldering fires in loose fill wood fibre building insulation, focusing on the effect of fire retardant content and fibre size. The study is a part of the EMRIS (Emerging Risks from Smoldering Fires) project. The test set-up is shown in Fig 1a [3]. The tested material was 100 grams, 34 kg/m3 spruce wood fibre loose-fill insulation with 4 and 9 % added ammonium polyphosphate fire retardant. Tests with short, fine fibres (Fig 1b) were compared to testst with long, thin fibres. The sample was heated from below until a given temperature was obtained 20 mm above the heater. Temperature and mass loss measurements as well as visual observations of the residue after test (Fig 1c) were used to characterize the onset of self-sustained smouldering. An iterative process was used, with 5 to 8 tests per product. It was found that a high level (9 %) of fire retardant gave an onset of smoldering at lower temperatures (225 °C) compared to a low level (4 %) of fire retardant (290 °C). The lower onset temperature indicates that the insulation with the highest fire retardant content is more prone to smouldering, which is contradictory to the expected performance of the fire retardant. For the same fire retardant content, the onset of self-sustained smouldering combustion was obtained at lower temperatures in insulation materials with smaller fiber sizes than in insulation with larger fiber size (225 vs 280 °C). This study is indicative, the absolute temperatures relate to the given test set-up. Further studies should include a range of fire retardant types and content, to obtain knowledge on their effect on smouldering fires.

  • 3.
    Eidissen Jensen, Ulla
    et al.
    NTNU Norwegian University of Science and Technology, Norway.
    Steen-Hansen, Anne
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Fire Research AS, Norge. Stord/Haugesund University College, Norway.
    Fjellgaard Mikalsen, Ragni
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Fire Research AS, Norge.
    Development of smouldering combustion in loose-fill wood fibre building insulation2016Ingår i: Book of Abstracts Nordic Fire & Safety Days 2016, 2016, s. 7-7Konferensbidrag (Övrigt vetenskapligt)
  • 4.
    Fjellgaard Mikalsen, Ragni
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge. Western Norway University of Applied Sciences, Norway; Otto von Guericke University Magdeburg, Germany.
    Fighting flameless fires: Initiating and extinguishing self-sustainedsmoldering fires in wood pellets2018Doktorsavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    Smoldering fires represent domestic, environmental and industrial hazards. This flameless form of combustion is more easily initiated than flaming, and is also more persistent and difficult to extinguish. The growing demand for non-fossil fuels has increased the use of solid biofuels such as biomass. This represents a safety challenge, as biomass self-ignition can cause smoldering fires, flaming fires or explosions.

    Smoldering and extinguishment in granular biomass was studied experimentally. The set-up consisted of a cylindrical fuel container of steel with thermally insulated side walls. The container was closed at the bottom, open at the top and heated from below by a hot surface. Two types of wood pellets were used as fuel, with 0.75-1.5 kg samples.

    Logistic regression was used to determine the transition region between non-smoldering and self-sustained smoldering experiments, and to determine the influence of parameters. Duration of external heating was most important for initiation of smoldering. Sample height was also significant, while the type of wood pellet was near-significant and fuel container height was not.

    The susceptibility of smoldering to changes in air supply was studied. With a small gap at the bottom of the fuel bed, the increased air flow in the same direction as the initial smoldering front (forward air flow) caused a significantly more intense combustion compared to the normal set-up with opposed air flow.

    Heat extraction from the combustion was studied using a water-cooled copper pipe. Challenges with direct fuel-water contact (fuel swelling, water channeling and runoff) were thus avoided. Smoldering was extinguished in 7 of 15 cases where heat extraction was in the same range as the heat production from combustion. This is the first experimental proof-of-concept of cooling as an extinguishment method for smoldering fires.

    Marginal differences in heating and cooling separated smoldering from extinguished cases; the fuel bed was at a heating-cooling balance point. Lower cooling levels did not lead to extinguishment, but cooling caused more predictable smoldering, possibly delaying the most intense combustion. Also observed at the balance point were pulsating temperatures; a form of long-lived (hours), macroscopic synchronization not previously observed in smoldering fires.

    For practical applications, cooling could be feasible for prevention of temperature escalation from self-heating in industrial storage units. This study provides a first step towards improved fuel storage safety for biomass. 

  • 5.
    Fjellgaard Mikalsen, Ragni
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge.
    Studie av synlighet til høytmonterte markeringsskilt i brannrøyk2015Rapport (Refereegranskat)
  • 6.
    Fjellgaard Mikalsen, Ragni
    et al.
    RISE Research Institutes of Sweden, Säkerhet och transport, Brandteknik.
    Durgun, Özum
    RISE Research Institutes of Sweden, Samhällsbyggnad, Systemomställning och tjänsteinnovation.
    Williams Portal, Natalie
    RISE Research Institutes of Sweden, Material och produktion, Tillämpad mekanik.
    Orosz, Katalin
    RISE Research Institutes of Sweden, Material och produktion, Tillämpad mekanik.
    Honfi, Daniel
    RISE Research Institutes of Sweden, Samhällsbyggnad, Bygg och fastighet.
    Reitan, Nina Kristine
    RISE Research Institutes of Sweden, Säkerhet och transport, Brandteknik.
    Efficient emergency responses to vehicle collision, earthquake, snowfall, and flooding on highways and bridges: A review2020Ingår i: Journal of Emergency Management, ISSN 1543-5865, Vol. 18, nr 1, s. 51-72Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This review article analyzes factors affecting emergency response to hazardous events on highways and their bridges, with focus on man-made and natural scenarios: heavy vehicle collision with a bridge, earthquake, heavy snowfall, and flooding. For each disaster scenario, selected historical events were compiled to determine influential factors and success criteria for efficient emergency response, both related to organizational and technical measures. This study constituted a part of a resilience management process, recently developed and demonstrated within the European Union (EU)-funded H2020 project IMPROVER and can be a useful approach in aiding operators of transportation infrastructure to improve their resilience to emergency incidents.

  • 7.
    Fjellgaard Mikalsen, Ragni
    et al.
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge.
    Glansberg, Karin
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge.
    Daaland Wormdahl, Espen
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge.
    Stolen, Reidar
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge.
    Jet fires and cryogenic spills: How to document extreme industrial incidents2019Ingår i: Sixth Magdeburg Fire and Explosion Days (MBE2019) conference proceedings, , 2019Konferensbidrag (Refereegranskat)
    Abstract [en]

    In industrial plants, such as oil platforms, refineries or onboard vessels carrying fuel, a rupture event of a pipeline could have dramatic consequences, as was demonstrated both in the Piper Alpha and Deepwater Horizon accidents. If surfaces are exposed to extreme conditions, both extreme cold (cryogenic spills) and extreme heat (jet fires), this can affect exposed surfaces, and can cause a domino effect of severe events.

  • 8.
    Fjellgaard Mikalsen, Ragni
    et al.
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge.
    Glansberg, Karin
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge.
    Storesund, Karolina
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge.
    Ranneklev, Sissel
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge.
    Branner i avfallsanlegg2019Rapport (Övrigt vetenskapligt)
    Abstract [en]

    Waste facilities represent a vital function in society, but fires occur regularly. The aim of this study is to provide a knowledge base on risks associated with fires in waste facilities, and to identify measures that can prevent fire and limit the extent of fire damage and environmental impact.

    Information was obtained through meetings with the waste industry, two inspections at waste facilities, a survey, a literature review and a review of the events registered in the fire and rescue services' reporting solution BRIS, as well as communication with other stakeholders. The project included land-based waste management; facilities for the reception and storage of waste (N=661), reception and storage of hazardous waste (N=250), and treatment facilities for hazardous waste (N=38). Waste treatment plants (such as biogas- or incinerator plants) as well as landfills are not included.

    High-risk waste types have been found to be general, residual waste, batteries (especially batteries not correctly sorted), electrical and electronic (EE) waste, as well as paper, paperboard and cardboard. General, residual waste stands out as an important focus area for reducing the overall fire risk at Norwegian waste facilities, both based on reported frequency of fire ignition and potential consequences with regard to equipment, downtime, environment and health. Waste categorized as "Hazardous Waste" does

    not stand out, and is not ranked in the highest risk category in this study, since many preventive and damage reducing measures have been implemented, and appear to work. Chapter 9 provides details on rating of fire risk.

    In the period January 2016 - May 2019, 141 fires were reported in waste facilities in Norway in BRIS. The total number of fires (including small, medium and large fires) is unknown, but is believed to be far higher. Common sources of ignition have been found to be composting (self-ignition), thermal runaway in batteries, heat friction by grinding, human activity and unknown cause.

    Regularly occurring fires outdoors, increased use of indoor storage and new types of waste such as lithium batteries lead to a risk that is difficult to manage, which can be a challenge with regard to insurance of waste facilities. Increased use of indoor storage is motivated by consideration for the environment and neighbours, but it may conflict with fire safety, especially because it restricts the access for the fire fighters and because of possible high heat stress on the load-bearing structure of the building housing the waste.

    Any major fire, regardless of the type of waste burned, could potentially lead to the release of pollutants into the air, water or soil. All smoke from fires can be harmful to humans and exposure to it must be taken seriously. There is a need for more knowledge and expertise in assessing emissions and environmental consequences in connection with firefighting. The use of extinguishing foam can reduce the consumption of extinguishing water, but the foam itself can contribute to contamination if discharged into water. A more detailed list of chemical content in the foam product data sheet is needed in order to be able to assess environmental concerns during use.

    2

    © RISE Research Institutes of Sweden

    Measures have been proposed for the design of more firesafe facilities, for waste management and for limiting the environmental impact during and after a fire. Key measures that should be prioritized are detection and monitoring, limiting the amounts of waste, tidiness, sufficient training, reception control, available and properly dimensioned fire extinguishing equipment, as well as solutions to collect extinguishing water in order to prevent the release of environmental toxins. It has not been possible to verify the effect of individual measures based on available data and statistics. The industry’s own overall assessment has been found to be consistent with experience-based observations found in other studies, and this has been found to be the best available information on effective measures. The responsibility for most of the measures lies with the owner of the facility or the business, and the focus should be on the use of documented technical solutions and the assessment of whether measures are appropriate and practicable at each facility. A fire risk assessment, locally adapted to the respective facility is important, as there are large variations in the types of waste handled, the size and the design of facilities, as well as other local conditions that differ between waste facilities in Norway. The fire service should strive to achieve a close dialogue and cooperation with the waste facilities. The authorities should facilitate better knowledge transfer and learning after fires, between different fire departments. The authorities should also, in collaboration with the industry, develop a national attitude campaign to avoid faulty battery sorting.

    Further work should study extinguishing techniques and extinguishing tactics that can limit the amount of water needed and that can be used during large-scale fires. Various detection and extinguishing solutions for use at waste facilities should be surveyed, assessed with regards to suitability and documented in cases where documentation is lacking. This should be made available on an openly accessible platform. There is also a need for further studies on the chemical composition of smoke from different types of waste fires, as well as studies on the extent and spread of fire smoke and environmental impacts from fires on water recipients.

    Increased fire safety at waste facilities could facilitate a better dialogue between industry and insurance providers by reducing potential financial losses. Good handling of fire risk in waste facilities will not only affect the plants themselves, but will also limit potential societal costs and consequences for health and the environment.

  • 9.
    Fjellgaard Mikalsen, Ragni
    et al.
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge. Western Norway University of Applied Sciences, Norway; Otto von Guericke University Magdeburg, Germany.
    Hagen, Bjarne C.
    Western Norway University of Applied Sciences, Norway.
    Frette, Vidar
    Western Norway University of Applied Sciences, Norway.
    Synchronized smoldering combustion2018Ingår i: Europhysics letters, ISSN 0295-5075, E-ISSN 1286-4854, Vol. 121, nr 5, s. 50002-p1-50002-p2Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Synchronized, pulsating temperatures are observed experimentally in smoldering fires.The entire sample volume (1.8 l) participates in the pulsations (pulse period 2–4 h). The synchronylasts up to 25 h and is followed by a spontaneous transition to either disordered combustion orself-extinguishment. The synchronization is obtained when the fuel bed is cooled to the brink ofextinguishment. Calculations for adiabatic conditions, including heat generation from combustion(nonlinear in temperature) and heat storage in sample (linear in temperature), predict divergingsample temperature. Experimentally, heat losses to surroundings (linear in temperature) preventtemperatures to increase without bounds and lead to pulsations.

  • 10.
    Fjellgaard Mikalsen, Ragni
    et al.
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge. Western Norway University of Applied Sciences, Norway.
    Hagen, Bjarne Christian
    Western Norway University of Applied Sciences, Norway.
    Emerging Risks from Smoldering Fires: Results from the EMRIS project2018Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    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.

  • 11.
    Fjellgaard Mikalsen, Ragni
    et al.
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge. Western Norway University of Applied Sciences, Norway.
    Hagen, Bjarne Christian
    Western Norway University of Applied Sciences, Norway.
    Steen-Hansen, Anne
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge.
    Frette, Vidar
    Western Norway University of Applied Sciences, Norway.
    Extinguishing smoldering fires in wood pellets through cooling2017Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    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.

  • 12.
    Fjellgaard Mikalsen, Ragni
    et al.
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge. Western Norway University of Applied Sciences, Norway.
    Hagen, Bjarne Christian
    Western Norway University of Applied Sciences, Norway.
    Steen-Hansen, Anne
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge.
    Frette, Vidar
    Western Norway University of Applied Sciences, Norway.
    Smoldering combustion- from pulsations to extinguishment2017Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    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.

  • 13.
    Fjellgaard Mikalsen, Ragni
    et al.
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge. Western Norway University of Applied Science, Norway; Otto von Guericke University Magdeburg, Germany.
    Hagen, Bjarne Christian
    Western Norway University of Applied Science, Norway.
    Steen-Hansen, Anne
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge.
    Krause, Ulrich
    Otto von Guericke University Magdeburg, Germany.
    Frette, Vidar
    Western Norway University of Applied Science, Norway.
    Extinguishing Smoldering Fires in Wood Pellets with Water Cooling: An Experimental Study2019Ingår i: Fire technology, ISSN 0015-2684, E-ISSN 1572-8099, Vol. 25, nr 1, s. 257-284Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    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.

  • 14.
    Fjellgaard Mikalsen, Ragni
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Fire Research AS, Norge.
    Haraldseid, Ingunn
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Fire Research AS, Norge.
    Villacorta, Edmundo
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Fire Research AS, Norge.
    Hagen, Bjarne C.
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Fire Research AS, Norge.
    Steen-Hansen, Anne
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Fire Research AS, Norge.
    Frette, Vidar
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Fire Research AS, Norge.
    Emerging Risks from Smoldering Fires2015Konferensbidrag (Övrigt vetenskapligt)
  • 15.
    Fjellgaard Mikalsen, Ragni
    et al.
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge.
    Sæter Bøe, Andreas
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge.
    Glansberg, Karin
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge.
    Sesseng, Christian
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge.
    Storesund, Karolina
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge.
    Stolen, Reidar
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge.
    Brandt, Are W.
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge.
    Energieffektive bygg og brannsikkerhet2019Rapport (Övrigt vetenskapligt)
  • 16.
    Rebaque, Virginia
    et al.
    NTNU Norwegian University of Science and Technology, Norway.
    Ertesvåg, Ivar
    NTNU Norwegian University of Science and Technology, Norway.
    Fjellgaard Mikalsen, Ragni
    RISE Research Institutes of Sweden, Säkerhet och transport, Brandteknik. Western Norway University of Applied Sciences, Norwaay; Otto von Guericke University Magdeburg, Germany.
    Steen-Hansen, Anne
    RISE Research Institutes of Sweden, Säkerhet och transport, Brandteknik.
    Experimental study of smouldering in wood pellets with and without air draft2020Ingår i: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 264, artikel-id 116806Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Dry wood pellets (diameter 8 mm) of mixed Norwegian spruce and pine were tested in samples of 1.25 kg (1.7 l) in configurations with and without air draft from below. The pellets were placed in a vertical 15 cm diameter cylinder on top of a hot plate. Air draft inlet, when allowed, came through narrow openings in the cylinder bottom periphery. The bulk void of 36% formed channels for gas flows within the pellets bed. Initially, the samples were heated externally from below for 6 h. Time series of distributed temperatures were recorded, together with values of the mass. Smouldering with air draft was observed with two distinct behaviours: Type 1, where the sample after the period of external heating cooled down for several hours, and then increased in temperature to intense smouldering, and Type 2, where the sample went into intense smouldering before the end of external heating. Without draft airflow from below, the sample cooled down after external heating, before developing into intense smouldering about 20 h later. In all cases, the intense period lasted for 2 h. Typical temperatures were in the range 300–450 °C, while higher temperatures occurred in the intense period. Draft flow caused fast oxidation spreading, while slow without draft. Indications of oxidation spreading as a distriäbuted reaction were seen. Circulating air motions in the irregular void between individual pellets is discussed as an explanation for the behaviour. Uneven access to oxygen, with possibilities of locally excess air, can explain the peak temperatures observed. © 2019 The Author(s)

  • 17.
    Reitan, Nina Kristine
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Fire Research AS, Norge.
    Fjellgaard Mikalsen, Ragni
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Fire Research AS, Norge.
    Sikker brensellagring i Norge2015Ingår i: Brandposten, nr 52, s. 24-25Artikel i tidskrift (Övrigt vetenskapligt)
  • 18.
    Reitan, Nina Kristine
    et al.
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge.
    Friquin, Kathinka
    SINTEF, Norway.
    Fjellgaard Mikalsen, Ragni
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge.
    Brannsikkerhet ved bruk av krysslaminert massivtre i bygninger – en litteraturstudie2019Rapport (Övrigt vetenskapligt)
    Abstract [en]

    © RISE Research Institutes of SwedenAbstractFire safety in cross laminated timber buildings; a reviewKey words: Cross laminated timber; CLT; fire safety; exposed CLT; auto-extinction; charring; delamination; detailingThis literature study presents recent research on fire safety in cross laminated timber (CLT) buildings. Results from large fire experiments and other studies in the period 2010 - 2018 are summarized, with focus on the following research questions:• How do constructions consisting of protected or exposed CLT contribute to the fire development in a room?• How can contribution to the fire development from detailing of CLT be avoided?There is an increasing desire to use wooden structures in tall buildings, as a substitute for more traditional construction materials. However, the use of combustible construc-tions in buildings in Norwegian Fire Class 3 (usually five floors or more) is not pre-accepted in the guideline to Regulations on technical requirements for construction works (TEK17), and fire safety must therefore be documented by analysis in such structures. When designing tall and complex timber buildings, it must be taken into account that a fire involving a timber construction may have more severe consequences than in buildings with constructions of steel or concrete, if the fire design of the construction and detail solutions is insufficient. Several studies show that fire exposed CLT, or CLT with insufficient protection, can cause a fire to develop faster, be more intense and last longer than a fire where the only fuel is the furniture and fixtures in the fire room. It is shown that the amount of fire exposed timber in a room may have impact on the extent and duration of a fire, but the knowledge has not yet been sufficient enough to be used in fire modeling, design and analysis.Research on charring rates, delamination and auto-extinction, all of which are factors that can have major impact on fire development and the fire resistance of the construction, takes place in Europe, Australia and North America. Although extensive research has been carried out, it is based on few large fire experiments, and the literature is still pointing to several knowledge gaps. However, the research projects have increased the knowledge of fire in timber buildings, and have contributed to the design of detail solutions, guidelines and development of models for function-based design. Revision of EN 1995-1-2 is under preparation and expected to apply from 2022. A knowledge base for the audit can be found in the network COST Action FP1404 Fire Safety Use of Bio-Based Building Products (COST FP1404) Working Group 2 (WG2). They have published several guidelines relevant for the fire design of CLT, including e.g. calculation methods for the prediction of charring rates and depths, determination of reduced CLT cross-section, design of CLT detailing and a suggested test method for evaluating adhesive performance.Based on the literature review, the following conclusions and recommendations are given for CLT constructions:• The design phase must sufficiently consider protection of the construction and con-tribution of the construction to the fire energy, and to a greater extent include the assessment of detailing and ventilation conditions. It should be considered whether analytic fire engineering design also should be required for buildings in the Norwegian Fire Classes 1 and 2 where more than one CLT wall is exposed.• By protecting all CLT surfaces of the structure with cladding, the construction may retain the stability and the load bearing capacity during the required time of fire resistance.• In buildings with only one exposed CLT wall in each fire cell, it may also be appropriate to use solutions that satisfy the pre-accepted performances, but one must consider whether a somewhat longer and more intense heat radiation and flame exposure on the facade outside window openings will require measures beyond the pre-accepted performances given in the guideline to TEK17.• Rooms where two or more CLT walls in addition to the ceiling are exposed, are configurations that should be avoided.• The risk of delamination can be reduced by using heat-resistant glue.• There is generally a need for relevant documentation for fire-resistant solutions for joints between CLT walls and floors and service penetrations in CLT constructions.• Test methods for testing of joints and penetrations in CLT constructions should be standardized. For example, there exists no standardized test for corner joints. Tests of penetration seals for CLT constructions are scarce, although they can be tested according to EN 1366-3. However, CLT is not a standard supporting construction according to EN 1366-3, and this must be taken into consideration when the test results are evaluated. Joints in glulam constructions should also be tested because they are often used in conjunction with CLT elements.

  • 19.
    Sesseng, Christian
    et al.
    RISE Research Institutes of Sweden, Säkerhet och transport, Brandteknik.
    Reitan, Nina Kristine
    RISE Research Institutes of Sweden, Säkerhet och transport, Brandteknik.
    Storesund, Karolina
    RISE Research Institutes of Sweden, Säkerhet och transport, Brandteknik.
    Fjellgaard Mikalsen, Ragni
    RISE Research Institutes of Sweden, Säkerhet och transport, Brandteknik. Otto von Guericke University Magdeburg, Germany; Western Norway University of Applied Sciences, Norway.
    Hagen, Bjarne
    Western Norway University of Applied Sciences, Norway.
    Effect of particle granularity on smoldering fire in wood chips made from wood waste: An experimental study2020Ingår i: Fire and Materials, ISSN 0308-0501, E-ISSN 1099-1018Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    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.

  • 20.
    Steen-Hansen, Anne
    et al.
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge.
    Bøe, Andreas G.
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge.
    Hox, Kristian
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge.
    Fjellgaard Mikalsen, Ragni
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge.
    Stensaas, Jan P.
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge.
    Storesund, Karolina
    Hva kan vi lære av brannen i Lærdal i januar 2014?: Vurdering av brannspredningen2014Rapport (Refereegranskat)
  • 21.
    Steen-Hansen, Anne
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Fire Research AS, Norge.
    Bøe, Andreas Gagnat
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Fire Research AS, Norge.
    Hox, Kristian
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Fire Research AS, Norge.
    Fjellgaard Mikalsen, Ragni
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Fire Research AS, Norge.
    Stensaas, Jan P.
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Fire Research AS, Norge.
    Storesund, Karolina
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Fire Research AS, Norge.
    Evaluation of Fire Spread in the large Lærdal Fire, January 20142015Ingår i: Conference proceedings from Fire and Materials 2015, 2015Konferensbidrag (Övrigt vetenskapligt)
  • 22.
    Steen-Hansen, Anne
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Fire Research.
    Fjellgaard Mikalsen, Ragni
    Hansen, Per Arne
    Wighus, Ragnar
    Hva tåler en brannvegg?2015Ingår i: Brandposten, nr 52, s. 34-35Artikel i tidskrift (Övrigt vetenskapligt)
  • 23.
    Steen-Hansen, Anne
    et al.
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge.
    Fjellgaard Mikalsen, Ragni
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge. Stord/Haugesund University College, Norway.
    Jensen, Ulla Eidissen
    NTNU Norwegian University of Science and Technology, Norway.
    Smouldering Combustion inLoose-Fill Wood Fibre Thermal Insulation: An Experimental Study2018Ingår i: Fire technology, ISSN 0015-2684, E-ISSN 1572-8099, Vol. 54, nr 6, s. 1585-1608Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A bench-scale experimental setup has been used to study the conditions necessary

    for smouldering ignition in four types of loose-fill wood fibre thermal insulation, and

    to study the development of the smouldering process. The products varied with regard to

    wood species, grain size and fire retardant chemical additives. The test material was

    placed in an insulated open top container and heated from below. Temperatures within

    the sample and mass loss were measured during the tests. Both the fibre size and the level

    of added fire retardant seem to influence the smouldering ignition. Two different types of

    smouldering were identified in this study. Materials undergoing smouldering Type 1

    obtained maximum temperatures in the range 380C to 440C and a total mass loss of

    40 wt% to 50 wt%. Materials undergoing smouldering Type 2 obtained maximum temperatures

    in the range 660C to 700C and a total mass loss of 80 wt% to 90 wt%. This

    implies that Type 2 smouldering involves secondary char oxidation, which represents a

    risk for transition to flaming combustion and thereby a considerable fire hazard. This has

    been an exploratory project and the results must therefore be considered as indicative.

    The findings may, however, have implications for fire safety in the practical use of loosefill

    wood fibre insulation in buildings, and further experimental studies should be performed

    with this in mind to obtain more knowledge about the topic.

  • 24.
    Steen-Hansen, Anne
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Fire Research AS, Norge.
    Storesund, Karolina
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Fire Research AS, Norge.
    Fjellgaard Mikalsen, Ragni
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Fire Research AS, Norge.
    Stensaas, Jan P.
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Fire Research AS, Norge.
    Bøe, Andreas Gagnat
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Fire Research AS, Norge.
    Hox, Kristian
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Fire Research AS, Norge.
    The Large Fire in Lærdal, January 2014. How did the Fire Spread and what Restricted the Fire Damage?2015Ingår i: Natural Disasters and Societal Safety / [ed] R.H. Gabrielsen & S. Lacasse, Oslo: Novus Forlag, 2015, s. 99-112Kapitel i bok, del av antologi (Övrigt vetenskapligt)
  • 25.
    Stolen, Reidar
    et al.
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge.
    Fjellgaard Mikalsen, Ragni
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge.
    Heat flux in jet fires: New method for measuring the heat flux levels of jet fires2018Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Jet fires are ignited leakages of pressurized liquid or gaseous fuel. In jet fire testing for the offshore industry, heat flux is the defining factor for the accidental loads. NORSOK S001 [1] defines two different heat flux levels of 250 kW/m2 and 350 kW/m2 depending on the leak rate of hydrocarbons. These heat flux levels are used in risk analysis and define what type of fire load bearing structures and critical equipment need to be able to resist in a given area. Examples of such ratings can be “250 kW/m2 jet fire for 60 minutes”, “350 kW/m2 jet fire for 15 minutes” or any other combination based on calculations in the risk assessment. Combined with critical temperatures this defines the performance criteria for the passive fire protection. Each configuration of the passive fire protection needs to be tested and verified. Manufacturers of passive fire protection request fire tests to document their performance against jet fires with these various heat flux levels. The challenge is that the standard for testing passive fire protection against jet fires [2] does not define any heat flux level or any method to define or measure it. We have developed a method for defining and measuring the heat flux levels in jet fires. This method can be used when faced with the challenge of testing passive fire protection against specific levels of heat flux. The method includes a custom test rig that allows jet fire testing with different heat flux levels. A large number of tests have been performed to verify the reproducibility and repeatability of the method. Heat flux is defined as the flow of energy through a surface. The heat flux from a fire to an engulfed surface of an object is dependent on both the engulfing flame and the properties of the surface. The properties of the surface may change during the exposure to the flame as it heats up and changes its surface properties. At some point the object inside the flame will reach a thermal equilibrium with the flame where the net flow of energy into the object is balanced by the energy emitted from the object. The heat flux for an object can be calculated as incident heat flux, emitted heat flux or net heat flux. A definition of heat flux needs to include parameters of the receiving object. These variations give a lot of degrees of freedom when calculating heat flux in a fire. Special water cooled gauges are designed to measure heat flux to a cooled surface, but these have proved to be very unreliable when placed inside a large fire. A more robust and easily defined method is to measure the equilibrium temperature inside an object placed inside the flame. This is the principle used in plate thermocouples used in fire resistance furnace testing [3]. In our experience, these plate thermocouples are often damaged during high heat flux jet fire tests. This raises questions to how long into the tests such measurements are reliable. Several other types of objects have been tested and the most convenient and reliable type was found to be simply a small 8 mm steel tube that is sealed in the end and has a thermocouple inside. One key difference between this small tube thermocouple and the plate thermocouple is that the plate thermocouple is directional and the tube is omnidirectional. Current works and tests will optimize the measuring objects in order to get the most relevant equilibrium temperature while still maintaining the robustness of the sensor during the test. The suggested heat flux calculation is to follow the Stefan-Boltzmann relation of temperature and heat flux. For a black body this gives 350 kW/m2 for 1303 °C and 250 kW/m2 for 1176 °C. A lower emissivity may be defined for the surface of the sensing object giving higher temperatures for the same flux levels. This method gives a simple, robust and reproducible correlation between heat flux levels and temperatures that can be measured during jet fire tests. The method does not differ between the varying convective and radiative heat transfer in the flame, but it is a representative measurement for the temperature that an object would reach when placed inside the flame.

  • 26.
    Stolen, Reidar
    et al.
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge.
    Fjellgaard Mikalsen, Ragni
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge.
    Glansberg, Karin
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge.
    Daaland Wormdahl, Espen
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge.
    Heat flux in jet fires : Unified method for measuring the heat flux levels of jet fires2018Ingår i: Nordic Fire and Safety Days (NFSD2018) Conference proceedings (with peer-review),, 2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    Passive fire protection materials are used to protect critical structures against the heat from fires. In process plants with pressurized combustible substances there may be a risk of jet fires. Through risk analysis the severity of these jet fires is determined and these result in fire resistance requirements with different heat flux levels for different segments. The relevant test standard for fire resistance against jet fires does not include any measurements or definitions of the heat flux in the test flame which the tested object is exposed to. This paper presents methods for reaching different heat flux levels and how to measure them in a jet fire with limited deviations from the established jet fire test standard.

  • 27.
    Stolen, Reidar
    et al.
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge.
    Fjellgaard Mikalsen, Ragni
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge.
    Stensaas, Reidar
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge.
    Solcelleteknologi og brannsikkerhet2018Rapport (Övrigt vetenskapligt)
    Abstract [no]

    Bruken av solcelleteknologi er i stor vekst i Norge. I denne studien er branntekniske utfordringer ved bruk av solcelleteknologi undersøkt, med hensyn på brannstart, brannspredning og brannslokking. Studien danner et kunnskapsgrunnlag for å ivareta brannsikkerheten under montering, drift og under slokkeinnsats, samt for å utforme et enhetlig og tydelig regelverk. Resultatene fra studien viser:

    Brannstart: Solcelleinstallasjoner inneholder mange koblingspunkt, som kan være potensielle tennkilder, og en liten mengde brennbare materialer. Dermed er det som trengs til stede for å starte en brann. Det er viktig at alle kontaktpunkter i solcelleinstallasjonen er robuste og tåler den påkjenningen de blir utsatt for gjennom sin levetid uten at det oppstår dårlig kontakt som kan føre til brann.

    Brannspredning: For utenpåmonterte solcellemoduler er det ofte en åpen luftspalte mellom modul og bygning. Dersom det er en brann i denne luftspalten, vil varmen kunne bli akkumulert, noe som kan føre til raskere og større brannspredning enn om bygningsoverflaten ikke hadde vært tildekket. I fullskalaforsøk med solcellemoduler montert på tak spredte brannen seg under hele arealet som var dekket av moduler, men stoppet da den nærmet seg kanten av dette arealet. Dette illustrerer viktigheten av at områder med solceller utenpå en bygning blir seksjonert for å unngå brannspredning. Eventuelt kan det benyttes mindre brennbare materialer på taket under solcellemodulene for å motvirke den økte varmepåkjenningen som solcellemodulene gir. Luftspalten mellom modul og bygning kan potensielt også gi endringer i luftstrømningen langs bygget, som igjen kan påvirke brannspredningen.

    Brannslokking: Brannvesenet har behov for informasjon om det er solcelleinstallasjon i bygget og hvilke deler av det elektriske anlegget som kan være spenningssatt. Under slokkeinnsats må brannvesenet ta hensyn til berøringsfare, og fare for at det kan oppstå lysbuer og andre feil som kan føre til nye antennelsespunkt. Ferskvann kan brukes som slokkemiddel, dette må spyles fra minimum 1 meters avstand med spredt stråle og minimum 5 meters avstand med samlet stråle. Solcellemoduler kan komplisere brannslokking ved at de danner en fysisk barriere mellom brannvesenet og brannen, samt fordi det må tas hensyn til plassering av spenningssatte komponenter. Når disse punktene er tatt høyde for, bør ikke utenpåmonterte solcelleinstallasjoner være et problem.

    Videre arbeid: For utenpåmonterte solcelleinstallasjoner, er det lite forskning på vertikal montering (på fasader), og hvordan en eventuell endret branndynamikk kan påvirke brannspredning og slokking. Videre er det i dag økende bruk av bygningsintegrerte solcelleinstallasjoner, noe som gir mange mulige nye utfordringer for brannsikkerheten og for regelverk, ettersom solcellen da er en del av bygningskroppen, samtidig som den er en elektrisk komponent. Tysk statistikk tyder på at brannrisiko for slike installasjoner kan være større enn for utenpåmonterte solcelleinstallasjoner, og dette vil det derfor være viktig å undersøke nærmere.

  • 28.
    Storesund, Karolina
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge.
    Ishol, Herbjörg M.
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge.
    Rømning i brann: funksjonen til ulike visuelle ledesystemer2014Rapport (Refereegranskat)
  • 29.
    Storesund, Karolina
    et al.
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge.
    Fjellgaard Mikalsen, Ragni
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge.
    Evaluating particle and gas transmission through firefighters’ clothing2019Ingår i: Interflam 2019: Conference Proceedings, 2019Konferensbidrag (Refereegranskat)
    Abstract [en]

    The goal of this project has been to establish new knowledge and methods for testing the penetration of hazardous soot and smoke particles into fire clothing. The aim has been to provide the basis for the development of new fire-fighter clothing with better protection against particle penetration. In cooperation with fire services, authorities and protection clothing producers, needs, requirements and recommendations have been investigated. For the documentation and relevant classification of protective clothing, test set-ups in small and larger scale have been developed. The aim has been to be able to achieve representative and repeatable fire- and smoke exposure for accurate measurement of the particle penetration into clothing and trough clothing layers for screening materials and design solutions. With regard to the performance of the clothing, the small-scale tests give indications of the textiles’ ability to block gases and particles from penetrating into the clothing. The large-scale tests give indications to how the design of the clothing as a whole is able to prevent intrusion of gases and particles.

  • 30.
    Valdés, Virginia
    et al.
    NTNU Norwegian University of Science and Technology, Norway.
    Fjellgaard Mikalsen, Ragni
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge. Stord/Haugesund University College, Norway.
    Steen-Hansen, Anne
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge.
    Smouldering fires in wood pellets: the effect of varying the airflow2017Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Smouldering is a flameless form of combustion, deriving its heat from heterogeneous reactions occurring on the surface of the fuel when heated in an oxidizer environment. Smouldering is of interest both as a fundamental combustion problem and as a practical fire hazard, for instance in industrial storage units [1]. Many materials can sustain a smouldering reaction, among them wood pellets, which are becoming more widely used as an alternative to oil -fired central heating in residential and industrial buildings. Smouldering fires are difficult to detect, becoming a hazard that must not be underestimated [2]. The influence of varying the airflow, using two different configurations of smouldering combustion was studied: reverse and forward propagation. These are defined according to the direction in which the smouldering reaction front propagates relative to the oxidizer flow. In reverse smouldering, the reaction front propagates in the opposite direction to the oxidizer flow. In forward smouldering the front propagates in the same direction as the oxidizer flow: convective transport is in the direction of the original fuel ahead, preheating it before the smoulder zone is reached.

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