| 1. |
- Andres, Blanca, et al.
(författare)
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Response of stone wool–insulated building barriers under severe heating exposures
- 2018
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Ingår i: Journal of Fire Sciences. - : SAGE Publications. - 0734-9041 .- 1530-8049. ; 36:4, s. 315-341
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Tidskriftsartikel (refereegranskat)abstract
- This article presents the experimental results of stone wool–layered sandwich constructions, with either steel or gypsum claddings, tested under four different heating exposures: 7 kW/m2 incident radiant heat flux exposure, 60 kW/m2 incident radiant heat flux exposure, parametric time–temperature curve exposure and ISO 834 standard time–temperature exposure. The test apparatus used were a movable radiant panel system, a mid-scale furnace (1.5 m3) and a large-scale furnace (15 m3). The results show that reduced-scale tests are capable of reproducing the heat transferred through the construction at large scale provided there is limited mechanical degradation. The results indicate that the availability of oxygen is fundamental to the fire behaviour of the sandwich composites tested. Reactions occurring in stone wool micro-scale testing, such as oxidative combustion of the binder or crystallisation of the fibres, have a limited effect on the temperature increase when wool is protected from air entrainment.
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| 2. |
- Flecknoe-Brown, Konrad Wilkens, et al.
(författare)
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Experimental and numerical investigation on fire behaviour of foam/fabric composites
- 2017
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Ingår i: 15th International Conference and Exhibition on Fire and Materials 2017. - 9781510846746 ; 1, s. 240-253
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Konferensbidrag (refereegranskat)abstract
- Upholstered furniture is a major contributor to the fuel load in a fire compartment. Modelling the fire behaviour of upholstered furniture would support performance based fire safety engineering, by allowing the specification of realistic fire scenarios. Modelling upholstered furniture composites in cone calorimeter test conditions is undertaken to validate fundamental assumptions about the fire behaviour of these combinations, without including complexities of a real sized system (e.g. constructional details of mattresses or sofas). Kinetic parameters were taken from micro combustion calorimeter tests and thermal properties were taken from literature and optimised using individual material cone calorimeter tests. A novel methodology of sample preparation was proposed for the cone calorimeter tests in an attempt to increase the one dimensionality of heat transfer. Modelling showed mixed results when compared with experiments. The results also indicated the models incapacity to capture material-material interactions, such as melting of polyester on the top of flexible polyurethane slab or shielding created by cotton residue to protect flexible polyurethane slab from heat exposure.
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| 3. |
- Livkiss, Karlis, et al.
(författare)
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Characterization of stone wool properties for fire safety engineering calculations
- 2018
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Ingår i: Journal of Fire Sciences. - : SAGE Publications. - 0734-9041 .- 1530-8049. ; 36:3, s. 202-223
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Tidskriftsartikel (refereegranskat)abstract
- Prediction of the insulating capability of building products in fire conditions would support the product development process. Stone wool insulation is a widely used material in fire barrier constructions. Due to the combustion of its organic content, the temperature inside stone wool can rise above the temperature of the exposed boundary. This temperature rise is difficult to predict. An extensive test program was performed to obtain the thermal and reaction kinetic properties of stone wool. The test methods included modified slug calorimeter, thermogravimetric analysis, differential scanning calorimetry, micro-scale combustion calorimetry and bomb calorimetry. The thermal conductivity in elevated temperatures was similar for all the investigated products. Two positive mass loss rate and heat release rate peaks were observed in temperatures between 20°C and 700°C. Reaction kinetic parameters were obtained and used in a finite difference model predicting the temperature increase in stone wool upon linear heating.
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| 4. |
- Livkiss, Karlis
(författare)
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Fires in Narrow Construction Cavities : Fire Dynamics and Material Fire Performance
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- There have recently been devastating fire incidents related to fire spread over ventilated façades. These incidents indicate gaps in our understanding of the fire behaviour of façades. This thesis takes a bottom-up approach to investigating fire behaviour in materials and elements associated with narrow cavities in modern constructions. Ventilated façade is a construction used as an example in this thesis, in which an air gap is introduced between the thermal insulation and the external cladding.Experimental and numerical studies were conducted of flame heights and heat fluxes to the surfaces inside cavities. An experimental programme comprising more than 75 individual tests was done with cavity widths between 2 cm and 10 cm, as well as four different heat release rates from the burner. The study showed increasing flame heights and heat flux as the cavity width is reduced. In this experimental study, the flame height increased up to 2.2 times compared to those near one wall. FDS version 6.7.0 software was then used to assess its capability to replicate the experimental results. One of the identified limitations of FDS was the required small mesh cell size. Furthermore, the thermal response of stone wool and expanded polystyrene when exposed to fire conditions was studied. Four types of stone wool with densities of 37 to 154 kg/m3 were investigated experimentally and numerically. Thermogravimetric analysis and micro combustion calorimetry were used to characterize the thermal decomposition of the stone wool’s organic content. A numerical heat conduction model was developed and showed capability of reproducing the temperatures inside stone wool with relatively low density. Suggestions are provided for improving the model’s performance for high density wools.
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| 5. |
- Livkiss, Karlis, et al.
(författare)
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Flame Heights and Heat Transfer in Façade System Ventilation Cavities
- 2018
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Ingår i: Fire Technology. - : Springer Science and Business Media LLC. - 0015-2684 .- 1572-8099. ; 54:3, s. 689-713
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Tidskriftsartikel (refereegranskat)abstract
- The design of buildings using multilayer constructions poses a challenge for fire safety and needs to be understood. Narrow air gaps and cavities are common in many constructions, e.g. ventilated façade systems. In these construction systems flames can enter the cavities and fire can spread on the interior surfaces of the cavities. An experimental program was performed to investigate the influence of the cavity width on the flame heights, the fire driven upward flow and the incident heat fluxes to the inner surfaces of the cavity. The experimental setup consisted of two parallel facing non-combustible plates (0.8 × 1.8 m) and a propane gas burner placed at one of the inner surfaces. The cavity width between the plates ranged from 0.02 m to 0.1 m and the burner heat release rate was varied from 16.5 kW to 40.4 kW per m of the burner length. At least three repeated tests were performed for each scenario. In addition, tests with a single plate were performed. The flame heights did not significantly change for Q′/W < 300 kW/m2 (where Q′ is the heat release rate per unit length of the burner and W is the cavity width). For higher Q′/W ratios flame extensions up to 2.2 times were observed. When the distance between the plates was reduced or the heat release rate was increased, the incident heat fluxes to the inner surface increased along the entire height of the test setup. The results can be used for analysing methodologies for predicting heat transfer and fire spread in narrow air cavities.
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| 6. |
- Livkiss, Karlis, et al.
(författare)
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Numerical study of a fire-driven flow in a narrow cavity
- 2019
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Ingår i: Fire Safety Journal. - : Elsevier BV. - 0379-7112. ; 108
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Tidskriftsartikel (refereegranskat)abstract
- Air cavities and gaps between material layers are common in construction systems, e.g. ventilated façades. Air cavity may provide a pathway for smoke and flame spread in case of fire. Performing physical testing to investigate different systems and fire scenarios is resource demanding. Fire Dynamics Simulator (FDS version 6.7.0) was used to simulate fire driven flow between two parallel vertical walls. Flame heights, thermal impact to the interior wall surface and upward flow velocities were predicted with FDS and compared with experimental results. The fire source was a propane burner with 8 × 391 mm2 gas outlet area. Heat release rates were 6.6 kW and 12.4 kW and the distance between the parallel walls was 40 mm. Two different convective heat transfer coefficient sub grid scale models available in FDS were investigated. In this study the cavity width to mesh cell size ratio was equal or above 10, resulting in good predictions of flame heights, upward flow velocities and wall temperatures. 2 mm grid resulted in 25% lower HRR in locations near the burner gas inlet, compared to 4 mm grid, indicating the importance of well resolved gas outlet boundary.
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| 7. |
- Van Hees, Patrick, et al.
(författare)
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Analysis of fire barriers with respect to fires with combustible gases and liquids
- 2017
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Ingår i: 15th International Conference and Exhibition on Fire and Materials 2017. - 9781510846746 ; 1, s. 146-157
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Konferensbidrag (refereegranskat)abstract
- Fires including flammable gases and/or liquids differ from typical residential fires where the fuel is mainly composed of solid combustibles. The traditional ISO 834 curve was established to represent the timetemperature curve for a fully developed fire. However for combustible gases the type of thermal exposure might be substantially different and therefore other curves have been developed such as the hydrocarbon curve (HCC) and the jetfire exposure. Knowledge on how test results from traditional ISO 834 fire test can be used to estimate the behaviour under HCC or jetfire conditions is limited. The Swedish Contingency Agency MSB initiated research on this topic to find correlation or guidance rules. For this reason, both literature studies, statistical studies, calculation and fire tests were performed. Fire tests were performed at different scales and levels, and this paper focuses mainly on a real scale fire test conducted in a 2-container set-up where one of the containers doors was replaced by a typical fire barrier. It was observed that the exposure in a real fire is different with respect to pressure, temperature levels and temperature distributions. While the real fire test had a long period of lower room temperatures before it fully developed, the unequal temperature distribution as well as the radiative heat transfer from the pool fire resulted in a fire resistance, which was close to the rating of the wall according to ISO 834. Taking into account the results of the other fire test as well as calculations, it could be concluded that heat exposure from hydrocarbon fires will lead to a substantial decrease of fire rating. On top of this it was observed that certain materials do not resist sufficiently to, for example a jet fire exposure. Hence it is important to perform a full risk analysis when choosing an appropriate fire barrier for fires, which can include combustible gases and liquids.
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