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Compartment Fire Temperature Calculations and Measurements
Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.ORCID iD: 0000-0002-3112-0270
2017 (English)Doctoral thesis, comprehensive summary (Other academic)Alternative title
Mätning och beräkning av temperatur i brandceller (Swedish)
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.

Abstract [sv]

Denna avhandling behandlar problem kopplade till värmeöverföring och branddynamik i slutna utrymmen med tonvikt på värmeöverföring mellan gaser och utsatta konstruktioner. Avhandlingen består av en huvuddel och ett appendix innehållande sju vetenskapliga artiklar. I huvuddelen sammanfattas och diskuteras grundläggande teorier och principer inom värmeöverföring och branddynamik samt studier av ett antal specialfall av brandscenarion som baseras på dessa teorier. I de avslutande bilagorna (Artiklar A1-A3 och Artiklar B1-B2) finns sju vetenskapliga artiklar som grundligare beskriver de ovan nämnda specialfallen.

Huvudfokus i avhandlingen ligger på temperaturutveckling vid brand i slutna utrymmen. I avhandlingen studeras i synnerhet en- och två-zonsmodeller för brand i slutna utrymmen, och en ny metod för att beräkna brandgastemperaturer före och efter övertändning i rumsbränder är framtagen. Validering av dessa modeller med experiment visar att deras noggrannhet är bra. Modellerna visar också att de termiska egenskaperna hos de omgivande ytorna har stor inverkan på brandtemperatursutvecklingen. I tillägg studeras i denna avhandling betydelsen av val av mätmetoder i brandtekniska tillämpningar. På grundval av slutsatserna från dessa studier har de främsta mätteknikerna använts i ytterligare experimentella studier av olika brandscenarier.

Place, publisher, year, edition, pages
Luleå University of Technology, 2017.
Series
Doctoral thesis / Luleå University of Technology 1 jan 1997 → …, ISSN 1402-1544
Keyword [en]
compartment fire temperature, heat transfer, FEM, calculation of temperature, temperature measurement, fire scenario, validation, flashover
National Category
Other Engineering and Technologies
Research subject
Steel Structures
Identifiers
URN: urn:nbn:se:ltu:diva-59927ISBN: 978-91-7583-812-0 (print)ISBN: 978-91-7583-813-7 (electronic)OAI: oai:DiVA.org:ltu-59927DiVA: diva2:1072078
Public defence
2017-03-20, F1031, Luleå tekniska universitet, Luleå, 13:00 (English)
Opponent
Supervisors
Available from: 2017-02-09 Created: 2016-10-24 Last updated: 2017-12-01Bibliographically approved
List of papers
1. Measurement and calculation of adiabatic surface temperature in a full-scale compartment fire experiment
Open this publication in new window or tab >>Measurement and calculation of adiabatic surface temperature in a full-scale compartment fire experiment
2013 (English)In: Journal of fire sciences, ISSN 0734-9041, E-ISSN 1530-8049, Vol. 31, no 1, 35-50 p.Article in journal (Refereed) Published
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.

National Category
Building Technologies
Research subject
Steel Structures
Identifiers
urn:nbn:se:ltu:diva-2964 (URN)10.1177/0734904112453012 (DOI)0b5dd423-4815-465d-87f8-b364cf859354 (Local ID)0b5dd423-4815-465d-87f8-b364cf859354 (Archive number)0b5dd423-4815-465d-87f8-b364cf859354 (OAI)
Note
Validerad; 2013; 20120806 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2017-12-01Bibliographically approved
2. Large scale test on a steel column exposed to localized fire
Open this publication in new window or tab >>Large scale test on a steel column exposed to localized fire
Show others...
2014 (English)In: Journal of Structural Fire Engineering, ISSN 2040-2317, E-ISSN 2040-2325, Vol. 5, no 2, 147-160 p.Article in journal (Refereed) Published
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.

National Category
Building Technologies
Research subject
Steel Structures
Identifiers
urn:nbn:se:ltu:diva-8321 (URN)10.1260/2040-2317.5.2.147 (DOI)6d3e8b15-8bf6-439d-b07f-5514f185b1b5 (Local ID)6d3e8b15-8bf6-439d-b07f-5514f185b1b5 (Archive number)6d3e8b15-8bf6-439d-b07f-5514f185b1b5 (OAI)
Note
Validerad; 2014; 20140812 (alebys)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2017-12-01Bibliographically approved
3. Use of plate thermometers for better estimate of fire development
Open this publication in new window or tab >>Use of plate thermometers for better estimate of fire development
2011 (English)In: Performance, Protection and Strengthening of Structures under Extreme Loading / [ed] Ezio Cadoni; Marco di Prisco, Trans Tech Publications Inc., 2011, 362-367 p.Conference paper, Published paper (Refereed)
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.

Place, publisher, year, edition, pages
Trans Tech Publications Inc., 2011
Series
Applied Mechanics and Materials, ISSN 1660-9336 ; 82
National Category
Building Technologies
Research subject
Steel Structures
Identifiers
urn:nbn:se:ltu:diva-32397 (URN)6e5975df-fcd3-49ac-8045-ab4475e14c38 (Local ID)6e5975df-fcd3-49ac-8045-ab4475e14c38 (Archive number)6e5975df-fcd3-49ac-8045-ab4475e14c38 (OAI)
Conference
International Workshop on Performance, Protection and Strengthening of Structures under Extreme Loading : 30/08/2011 - 01/09/2011
Note
Validerad; 2011; 20111024 (ysko)Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2017-12-01Bibliographically approved
4. Thermal analysis of a pool fire test in a steel container
Open this publication in new window or tab >>Thermal analysis of a pool fire test in a steel container
2012 (English)In: Journal of fire sciences, ISSN 0734-9041, E-ISSN 1530-8049, Vol. 30, no 2, 170-184 p.Article in journal (Refereed) Published
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.

National Category
Building Technologies
Research subject
Steel Structures
Identifiers
urn:nbn:se:ltu:diva-14089 (URN)10.1177/0734904111432834 (DOI)d686907f-bca8-424d-8e24-3d0bc8068bcf (Local ID)d686907f-bca8-424d-8e24-3d0bc8068bcf (Archive number)d686907f-bca8-424d-8e24-3d0bc8068bcf (OAI)
Note
Validerad; 2012; 20120123 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2017-12-01Bibliographically approved
5. Compartment fire temperature: a new simple calculation method
Open this publication in new window or tab >>Compartment fire temperature: a new simple calculation method
2015 (English)In: IAFSS - The International Association for Fire Safety Science: proceedings, ISSN 1817-4299, Vol. 11, 289-301 p.Article in journal (Refereed) Published
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.

National Category
Building Technologies
Research subject
Steel Structures
Identifiers
urn:nbn:se:ltu:diva-39172 (URN)10.3801/IAFSS.FSS.11-289 (DOI)dcfce1ae-ddea-484d-b48b-7de38c5a3f51 (Local ID)dcfce1ae-ddea-484d-b48b-7de38c5a3f51 (Archive number)dcfce1ae-ddea-484d-b48b-7de38c5a3f51 (OAI)
Conference
International Symposium on Fire Safety Science : 10/02/2014 - 14/02/2014
Note
Godkänd; 2015; 20140812 (alebys); Konferensartikel i tidskriftAvailable from: 2016-10-03 Created: 2016-10-03 Last updated: 2017-12-01Bibliographically approved
6. Temperature of post-flashover compartment fires: calculations and validation
Open this publication in new window or tab >>Temperature of post-flashover compartment fires: calculations and validation
2017 (English)In: Fire and Materials, ISSN 0308-0501, E-ISSN 1099-1018Article in journal (Refereed) Epub ahead of print
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].

Place, publisher, year, edition, pages
John Wiley & Sons, 2017
National Category
Other Engineering and Technologies not elsewhere specified Building Technologies
Research subject
Steel Structures
Identifiers
urn:nbn:se:ltu:diva-59976 (URN)10.1002/fam.2488 (DOI)
Available from: 2016-10-26 Created: 2016-10-26 Last updated: 2017-12-19
7. Pre-flashover compartment fire temperature: a new calculation model validated with experiments
Open this publication in new window or tab >>Pre-flashover compartment fire temperature: a new calculation model validated with experiments
(English)In: Fire safety journal, ISSN 0379-7112, E-ISSN 1873-7226Article in journal (Refereed) Submitted
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.

Keyword
two-zone fire model, flashover, compartment fire temperature, model validation
National Category
Other Engineering and Technologies
Identifiers
urn:nbn:se:ltu:diva-62019 (URN)
Available from: 2017-02-15 Created: 2017-02-15 Last updated: 2017-12-01

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