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  • 1.
    Byström, Alexandra
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Compartment Fire Temperature Calculations and Measurements2017Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This thesis is devoted to heat transfer and fire dynamics in enclosures. It consists of a main part which summarizes and discusses the theory of heat transfer, conservation of energy, fire dynamics and specific fire scenarios that have been studied. In the second part of this thesis, the reader will find an Appendix containing seven scientific publications in this field.

    In particular, one- and two-zone compartment fire models have been studied. A new way of calculating fire temperatures of pre- and post-flashover compartment fires is presented. Three levels of solution techniques are presented including closed form analytical expressions, spread-sheet calculations and solutions involving general finite element temperature calculations. Validations with experiments have shown good accuracy of the calculation models and that the thermal properties of the surrounding structures have a great impact on the fire temperature development. In addition, the importance of the choice of measurement techniques in fire engineering has been studied. Based on the conclusions from these studies, the best techniques have been used in further experimental studies of different fire scenarios.

  • 2.
    Byström, Alexandra
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Fire temperature development in enclosures: Some theoretical and experimental studies2013Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This thesis is devoted to problems connected to heat transfer and fire dynamics in enclosures. The thesis consists of a main part which summarizes and discusses the theory of heat transfer, conservation of energy and fire dynamics. Based on these theories, some cases of different fire scenarios have been analyzed. In the end of this thesis, the reader will find Paper I-IV containing four articles on the subject.The main focus of this thesis is fire temperature development in enclosures. For that reason, firstly, some experimental studies have been done using different thermo devices for measuring temperature. Based on the experience from these studies, temperatures measured with a Plate Thermometer have been used to predict and describe in a quantitative way the thermal exposure of structures. For more accurate prediction of this thermal exposure, PT and thin thermocouples measurements have been combined.This thesis summarizes the experimental data from two different setups. One was conducted in a large enclosure 20 m by 20 m and 20 m high. This experiment scenario can be characterized as localized fire. Another experiment was conducted in a compartment in full scale with a limited fire source, without reaching flashover. This second experiment did not reach flashover and can be categorized as a two-zone compartment fire. Moreover, the thesis contains a new way of analyzing a one-zone fire model intended for the analysis of fully developed ventilation controlled compartment fires.Temperature data from the localized fire experiment were collected with different designs of Plate Thermometers (PT), small thermocouples (Ø=0.25 mm) and thermocouples fixed to a steel column. Measured data were compared with calculated data applying the concept of adiabatic surface temperature. Temperatures thus obtained by finite element calculations using the softwarecode TASEF were in the good agreement with measured steel temperatures. The full scale compartment fire was conducted in a two-story concrete building. During the experiment, data were collected with PTs and thin thermocouples at different locations inside the compartment.In the new way of analyzing post-flashover compartments fires the effects of different parameters on the fire temperature development has been analyzed. The new method of analyzing the heat and mass balances of a compartment fire has made it possible to develop simple analytical as well as numerical mathematical solutions.

  • 3.
    Byström, Alexandra
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Cheng, Xudong
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Wickström, Ulf
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Veljkovic, Milan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Full-scale experimental and numerical studies on compartment fire under low ambient temperature2012Inngår i: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 51, s. 255-262Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A fire experiment with wood crib was conducted in a concrete building under low ambient temperature of −10 °C to explore fire development and temperature distribution. The concrete building consists of a two-storey compartment with the size of 9.0 m by 5.0 m by 4.8 m high and a four-storey stairwell with the size of 5.0 m by 2.4 m by 10.0 m high. The fuel mass loss rate and temperatures at different positions were measured. Two fire cases, with different assumed ambient temperatures of −10 °C and 20 °C respectively, were then simulated by using FDS software to investigate the effect of ambient temperature and compare with the experimental results. The numerical results show that the calculated heat release rate is in reasonably good agreement with the measured full-scale result before water suppression. The calculated temperatures in the hot combustion gas layer at different positions agree also very well with the measured values. However, the measured fresh air temperature at the floor level near the fire source is higher than the calculated value. This discrepancy may partly depend on measuring errors as analyzed in the paper.

  • 4.
    Byström, Alexandra
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Cheng, Xudong
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Wickström, Ulf
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Veljkovic, Milan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Measurement and calculation of adiabatic surface temperature in a full-scale compartment fire experiment2013Inngår i: Journal of fire sciences, ISSN 0734-9041, E-ISSN 1530-8049, Vol. 31, nr 1, s. 35-50Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Adiabatic surface temperature is an efficient way of expressing thermal exposure. It can be used for bridging the gap between fire models and temperature models, as well as between fire testing and temperature models. In this study, a full-scale compartment fire experiment with wood crib fuel was carried out in a concrete building. Temperatures were measured with plate thermometers and ordinary thermocouples. Five plate thermometers and five thermocouples with a diameter of 0.25 mm were installed at different positions. These two different temperature devices recorded different temperatures, especially near the floor surface. The adiabatic surface temperature was derived by a heat balance analysis from the plate thermometer measurements. The thermal inertia of the plate thermometer was taken into account to correct the measured results. In addition, the fire experiment scenario was also simulated with fire dynamics simulator. The fire source was specified as a given heat release rate, which was calculated from the measured mass loss rate of the wood fuel. The adiabatic surface temperatures at these measuring positions were simulated by the fire dynamics simulator model and compared with the experimental adiabatic surface temperatures. The comparative results showed that fire dynamics simulator predicted the adiabatic surface temperature accurately during the steady-state period.

  • 5.
    Byström, Alexandra
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Lind, Oskar
    Luleå tekniska universitet.
    Palmklint, Erika
    Luleå tekniska universitet.
    Jönsson, Petter
    Luleå tekniska universitet.
    Wickström, Ulf
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Analysis of a new plate thermometer: the copper disc plate thermometer2015Inngår i: Proceedings of the International Fire Safety Symposium 2015: Coimbra, Portugal, 20th-22nd April 2015 / [ed] João Paulo C Rodrigues, International Fire Safety Symposium , 2015, s. 453-460Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Two temperatures govern heat transfer to a surface of a solid body. One is the gas temperature which can be measured with thermocouples (TC) and the other the black body radiation temperature. The latter can also be expressed as the incident radiant heat flux. It is difficult to measure as radiometers cannot be used under hot fire conditions. Indirectly the radiation temperature can be obtained by measuring the Adiabatic Surface Temperature (AST) with plate thermometers (PT) for example as defined in the fire resistance furnace standards EN 1363-1 and ISO-834-1 combined with measurements of gas temperature with thin TC. In the test reported here a smaller gauge is used to measure adiabatic surface temperature at surfaces. It has been named copper disc Plate Thermometer (cdPT). Then a thin copper disc with an attached TC is mounted flush at the surface to obtain the AST in e.g. cone calorimeters according to ISO 5660. A main advantage of the cdPT is that it can record the AST before as well after a material has ignited. It can thereby be used to indicate ignition as well as continue recording the thermal exposure thereafter when ignition occurs the cdPT reacts immediately by displaying a quick temperature rise.

  • 6.
    Byström, Alexandra
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Sjöström, Johan
    SP Technical Research Institute of Sweden, Borås.
    Wickström, Ulf
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Lange, David
    SP Technical Research Institute of Sweden, Borås.
    Veljkovic, Milan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Large scale test on a steel column exposed to localized fire2014Inngår i: Journal of Structural Fire Engineering, ISSN 2040-2317, E-ISSN 2040-2325, Vol. 5, nr 2, s. 147-160Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A localized fire is a fire which in a compartment is unlikely to reach flash-over and uniform temperature distribution. Designing for localized fires is generally more difficult than for flash-over compartment fires because of the complexity of the problem. There is also a lack of experimental data. We report here on a full scale test series on a steel column exposed to localized fires. The setup is a 6 meters tall hollow circular column, ϕ = 200 mm with a steel thickness of 10 mm. The unloaded column was hanging centrally above different pool fires. Temperatures of gas and steel were measured by thermocouples, and adiabatic surface temperatures at the steel surface were measured by plate thermometers of various designs. The results are compared with estimates based on Eurocode 1991-1-2 which in all cases studied overestimate the thermal impact for this setup. The input from plate thermometers was used to compute the steel temperatures using finite element methods. Excellent agreement was found if the radiation exchange within the column due to asymmetry of the exposure was taken into account.

  • 7.
    Byström, Alexandra
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Sjöström, Johan
    Technical Research Institute of Sweden, SP.
    Wickström, Ulf
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Veljkovic, Milan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    A steel column exposed to localized fire2012Inngår i: Nordic Steel Construction Conference 2012: September 5-7, 2012 Oslo, Norway : Proceedings, Norwegian Steel Association , 2012, s. 401-410Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper we report on a series of experiments which were conducted in the large fire hall of SP’sThe unprotected steel column with Ø=200 mm and thikness 10 mm was placed with its base in a pan with the fuel and exposed to fires of various liquid fuels and magnitudes. Temperatures were recorded in the gas phase and in the steel. In the gas phase temperatures were measured with traditional thermocouples and Plate Thermometers (PTs). It was observed that measured temperatures were much lower than the correspond temperatures calculated based on the formulas presented in Eurocode 1991-1-2. For a better estimation of the steel temperatures the emissivity of the flame should be taken into account.

  • 8.
    Byström, Alexandra
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Sjöström, Johan
    Technical Research Institute of Sweden, SP.
    Wickström, Ulf
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Veljkovic, Milan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Large scale test to explore thermal exposure of column exposed to localized fire2012Inngår i: Proceedings of the 7th International Conference on Structures in Fire / [ed] Mario Fontana; Andrea Frangi; Markus Knobloch, Zurich: ETH Zurich, Institute of Structural Engineering , 2012, s. 185-194Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A localized fire is a fire in a compartment which is unlikely to reach flash-over or a uniform temperature distribution. Designing for localized fires are generally more difficult than for a typical room fire both because of the complexity of the problem as well as the lack of experimental data. We reports on a full scale test on a steel column exposed to a localized fire. The setup is a 6 meters hollow circular column, Ø=200 mm with a steel thickness of 10 mm. The unloaded column was hanging centrally above different pool fires. We report temperatures of gas and steel as well as those measured by plate thermometer of the somewhat asymmetric fires. The results are compared with estimates based on Eurocode 1991-1-2 which in all cases studied overestimates the thermal impact for this setup.

  • 9.
    Byström, Alexandra
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Wickström, Ulf
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Influence of surrounding boundaries on fire compartment temperature2015Inngår i: International Conference ‘’Applications of Structural Fire Engineering" / [ed] Wald F.,Bjegovic D.,Horova K.,Burgess I.,Jelcic Rukavina M., Prague: Czech Technical University , 2015Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper shows and demonstrates how an analysis of the energy and mass balance of a fully developed (ventilation controlled) compartment fire can be used as a basis for simple and accurate predictions of fire temperatures. The model has been applied on compartments of light weight concrete structures. A finite element FE analysis has been used to solve the heat transfer equation. Effects of moisture were considered for material properties of the surrounding structure. The results were validated with experiments. The model then accurately predicted the fire temperatures and among other things it showed the influence of moisture in the surrounding structure on the fire temperature. Parametric temperature curves according to EN 1991-1-2, 2002 were shown to overestimate the fire temperature.

  • 10.
    Byström, Alexandra
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Wickström, Ulf
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Pre-flashover compartment fire temperature: a new calculation model validated with experimentsInngår i: Fire safety journal, ISSN 0379-7112, E-ISSN 1873-7226Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A new two-zone model for computing temperature of pre-flashover compartment fires is introduced. This model predicts upper layer fire temperatures in compartments with semi-infinitely thick boundaries as well as with boundaries of insulated or non-insulated steel sheets. The mass flows of air and fire gases are assumed controlled by the plume entrainment depending on a prescribed heat release rate and plume height. The combustion is limited by the rate at which gaseous fuel (pyrolysis gases) is released. The model is based on the assumption that the heat release rate is equal to the heat lost by convection of air and radiation out through the opening(s) and by losses to the surrounding structures.

    For a constant heat release rate, this model yields the maximum upper layer temperature a fire would reach when lasting for a very long time as well as the fire temperature as a function of time depending on the inertia, on the design of the surrounding structure and on the ventilation conditions of the compartment.

    This model is validated by comparisons with very accurately defined and controlled experiments.

  • 11.
    Byström, Alexandra
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Wickström, Ulf
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Temperature of post-flashover compartment fires: calculations and validation2018Inngår i: Fire and Materials, ISSN 0308-0501, E-ISSN 1099-1018, Vol. 42, nr 3, s. 255-265Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper describes and validates by comparisons with tests a one-zone model for computing temperature of fully developed compartment fires. The model is based on an analysis of the energy and mass balance assuming combustion being limited by the availability of oxygen, i.e. ventilation controlled fire. It is demonstrated that the model can be used to predict fire temperatures in compartments with semi-infinitely thick boundaries as well as with boundaries of insulated and uninsulated steel sheets where the entire heat capacity of the surrounding structure is assumed to be concentrated to the steel core. That is so called lumped heat capacity is assumed.

    When developing the fire model a maximum fire temperature was defined depending on combustion efficiency and opening heights only. This temperature was then used as a thermal boundary condition to calculate the temperature of the surrounding structure. The fire temperature was then derived to be a weighted average between the maximum fire temperature and the current calculated surrounding structure surface temperature.

    A general finite element solid temperature calculation code (TASEF) was used to calculate the temperature in the boundary structure. With this code it is possible to analyze surrounding structures of various kinds comprising materials with properties varying with temperature as well as assemblies of various materials.

    The experiments referred to were accurately defined and surveyed. In all the tests a propane diffusion burner was used as the only fire source. Temperatures were measured with thermocouples and plate thermometers at several positions [1].

  • 12.
    Byström, Alexandra
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Wickström, Ulf
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Sjöström, Johan
    SP Technical Research Institute of Sweden, Sverige.
    Anderson, Johan
    Sverige.
    Project: Validation of a one-zone room fire model with well-defined experiments2016Annet (Annet (populærvitenskap, debatt, mm))
  • 13.
    Byström, Alexandra
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Wickström, Ulf
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Veljkovic, Milan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Use of plate thermometers for better estimate of fire development2011Inngår i: Performance, Protection and Strengthening of Structures under Extreme Loading / [ed] Ezio Cadoni; Marco di Prisco, Trans Tech Publications Inc., 2011, s. 362-367Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The concept of Adiabatic Surface Temperature (AST) opens possibilities to calculate heat transfer to a solid surface based on one temperature instead of two as is needed when heat transfer by both radiation and convection must be considered. The Adiabatic Surface Temperature is defined as the temperature of a surface which cannot absorb or lose heat to the environment, i.e. a perfect insulator. Accordingly, the AST is a weighted mean temperature of the radiation temperature and the gas temperature depending on the heat transfer coefficients. A determining factor for introducing the concept of AST is that it can be measured with a cheap and robust method called the plate thermometer (PT), even under harsh fire conditions. Alternative methods for measuring thermal exposure under similar conditions involve water cooled heat flux meters that are in most realistic situations difficult to use and very costly and impractical.This paper presents examples concerning how the concept of AST can be used in practice both in reaction-to-fire tests and in large scale scenarios where structures are exposed to high and inhomogeneous temperature conditions.

  • 14.
    Cheng, Xudong
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Byström, Alexandra
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Wickström, Ulf
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Veljkovic, Milan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Thermal analysis of a pool fire test in a steel container2012Inngår i: Journal of fire sciences, ISSN 0734-9041, E-ISSN 1530-8049, Vol. 30, nr 2, s. 170-184Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A pool fire test was conducted in an uninsulated steel container under low ambient temperature condition, at −20°C. The heat balance of the enclosure fire was analyzed. The size of the container was 12 m × 2.4 m and 2.4 m high, and it was made of 3-mm-thick steel. During the fire test, the fuel mass loss rate was recorded and the temperatures at different positions were measured with high-temperature thermocouples and plate thermometers. The fire scenario was simulated by using fire dynamics simulator software, and the simulated and measured results were compared. The coarse high-temperature thermocouple responded slower, and therefore, temperature measured by the high-temperature thermocouple was corrected to eliminate the effect of the thermal inertia. Furthermore, a simple two-zone model was proposed for estimating gas temperature in the enclosure of the highly conductive steel walls assuming a constant combustion rate. The convective and radiative heat transfer resistances at the inside and outside surfaces of the enclosure were analyzed.

  • 15.
    Cheng, Xudong
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Veljkovic, Milan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Byström, Alexandra
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Iqbal, Naveed
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Sandström, Joakim
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Wickström, Ulf
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Prediction of temperature variation in an experimental building2011Inngår i: Proceedings of International Conference Applications of Structural Fire Engineering: Prague, 29 April 2011, 2011, s. 387-392Konferansepaper (Fagfellevurdert)
  • 16.
    Sjöström, Johan
    et al.
    SP Technical Research Institute of Sweden, Borås, SP Sveriges Tekniska Forskningsinstitut, Brandteknik.
    Wickström, Ulf
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Byström, Alexandra
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Validation data for room fire models: Experimantal background2016Rapport (Annet vitenskapelig)
    Abstract [en]

    A series of room fire tests for enclosures with different wall materials have been conducted for the purpose of supplying validation data for enclosure fire models. The wall materials are varied between light weight concrete, mineral wool insulation, bare 3 mm steel, and finally insulated steel. All tests used a propane gas burner with a well-defined mass flux as a fire source. Temperatures of thermocouples and plate thermometers were measured as well as oxygen concentrations in the opening. For some tests the heat release rate (by oxygen consumption calorimetry) as well as O2, CO2 and CO concentrations were measured in addition.This report describes the instrumentation, fire scenarios, enclosure materials, and results from all the tests. All results are readily available as spreadsheet data for downloading. The report also contains short description showing the influence of different factors such as wall materials, heat release rates and burner placements.

  • 17.
    Wickström, Ulf
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Byström, Alexandra
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Compartment fire temperature: a new simple calculation method2015Inngår i: IAFSS - The International Association for Fire Safety Science: proceedings, ISSN 1817-4299, Vol. 11, s. 289-301Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper a new simple calculation method for compartment temperatures is derived. The method is applicable to post-flashover ventilation controlled fires. A parameter termed the ultimate compartment fire temperature is defined as the temperature obtained when thermal equilibrium is reached and thick compartment boundaries cannot absorb any more heat from the fire gases. This temperature depends only on the product of the heat of combustion and the combustion efficiency over the specific heat capacity of air. It is, however, independent of the air mass flow rate, and of the fire compartment geometry and the thermal properties of the compartment boundary materials. These parameters on the other hand govern the rate at which the fire temperature is increasing towards the ultimate temperature. It is shown how the fire temperature development as a function of time in some idealized cases may be calculated by a simple analytical closed form formula.The fire temperature developments of two types of compartment boundaries are presented, semi-infinitely thick and thin structures. It is also shown that for the semi-infinite case, the solution resembles the standard ISO 834/EN 1363-1 curve and the parametric fire curves according to Eurocode 1, EN 1991-1-2.

  • 18.
    Wickström, Ulf
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Byström, Alexandra
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Sjöström, Johan
    SP Sveriges Tekniska Forskningsinstitut, Brandteknik.
    Temperature measurements and modelling of flashed over compartment fires2016Inngår i: Proceedings of 14th International Conference and Exhibition on Fire Science and Engineering, 2016, Vol. 2, s. 949-960, artikkel-id 12Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper describes and validates by comparisons with test results a one-zone model for computing temperatures of compartment fires where flashover is reached. The model is based on an analysis of the energy and mass balance of a fully developed (ventilation controlled) compartment fire. It is demonstrated in this paper that the model can be used to predict fire temperatures in compartments with semi-infinite boundaries as well as with boundaries of insulated or uninsulated steel sheets where so called lumped heat capacity can be assumed. Comparisons are made with a series of experiments in compartments of light weight concrete, and insulated and non-insulated single sheet steel structures. A general finite element code has been used to calculate the temperature in the surrounding structures. The in this manner calculated surface temperatures yield the fire temperature as a function of time. By using a numerical tool like a finite element code it is possible to analyse fire compartment surrounding structures of various kinds and combinations of materials.Two new characteristic compartment fire temperatures have been introduced in this paper. They are the ultimate compartment fire temperature, which is the temperature reached when heat losses to surrounding structures as well radiation out through openings can be neglected, and the maximum compartment fire temperature, which is the temperature when only the losses to surrounding structures are neglected.The experiments referred to were accurately defined and surveyed. In all the tests a propane gas burner was used as the only fire source. Temperatures were measured with thermocouples and plate thermometers at several positions, and oxygen concentrations were measured in the fire compartment only opening. In some tests the heat release rate as well as the CO2 and CO concentrations were measured as well (Sjöström, et al., 2016).

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