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Fires in Narrow Construction Cavities : Fire Dynamics and Material Fire Performance

Livkiss, Karlis LU (2020)
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... (More)
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. (Less)
Please use this url to cite or link to this publication:
author
supervisor
opponent
  • Prof. Roguame, Thomas, Pprime Institute University of Poitiers, France.
organization
publishing date
type
Thesis
publication status
published
subject
keywords
Fire, Ventilated façade, flame height, Stone wool, expanded polystyrene, Fire Dynamics Simulator (FDS)
pages
133 pages
publisher
Division of Fire Safety Engineering, Lund University
defense location
Lecture hall V:B, building V, John Ericssons väg 1, Faculty of Engineering LTH, Lund University, Lund.
defense date
2020-02-28 09:15:00
ISBN
978-91-7895-395-0
978-91-7895-394-3
language
English
LU publication?
yes
id
b1267d63-308e-4369-8081-ec39b3fcbcfd
date added to LUP
2020-01-29 17:42:16
date last changed
2020-06-22 14:15:45
@phdthesis{b1267d63-308e-4369-8081-ec39b3fcbcfd,
  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.<br/>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.}},
  author       = {{Livkiss, Karlis}},
  isbn         = {{978-91-7895-395-0}},
  keywords     = {{Fire; Ventilated façade; flame height; Stone wool; expanded polystyrene; Fire Dynamics Simulator (FDS)}},
  language     = {{eng}},
  month        = {{02}},
  publisher    = {{Division of Fire Safety Engineering, Lund University}},
  school       = {{Lund University}},
  title        = {{Fires in Narrow Construction Cavities : Fire Dynamics and Material Fire Performance}},
  url          = {{https://lup.lub.lu.se/search/files/75629766/Thesis_Karlis_Livkiss.pdf}},
  year         = {{2020}},
}