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PhD thesis on fires in cavities, February 28

2020-02-07

On February 28th at 09.15, Karlis Livkiss will defend his PhD-thesis "Fires in Narrow Construction Cavities - Fire Dynamics and Material Fire Performance". The faculty opponent is prof. Thomas Rogaume, Université de Poitiers, France.

The act will take place in lecture hall V:B (at John Ericssons väg 1 in Lund) and will start with a 30 minutes presentation followed by a short break before the defence starts. The entire dissertation normally takes 2-3 hours. The entire session will be performed in English.

After the seminar, lunch will be served and if you want to participate, please send an e-mail to johanna.kruse@risk.lth.se no later than February 14th. No notification is needed to only attend the defence act.

The thesis (excluding papers) can be found here.

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.