Abstract
Fire is a real threat for people and property. However,
if the risks can be identified before the accident, the
consequences can be remarkably limited. The requirement
of fire safety is particularly important in places with
large number of people and limited evacuation
possibilities (e.g., ships and airplanes) and for places
where the consequences of fire may spread wide outside of
the fire location (e.g., nuclear power plants).
The prerequisite for reliable fire safety assessment is
to be able to predict the fire spread instead of
prescribing it. For predicting the fire spread
accurately, the pyrolysis reaction of the solid phase
must be modelled. The pyrolysis is often modelled using
the Arrhenius equation with three unknown parameters per
each reaction. These parameters are not material, but
model specific, and therefore they need to be estimated
from the experimental small-scale data for each sample
and model individually.
The typical fuel materials in applications of fire safety
engineers are not always well-defined or characterised.
For instance, in electrical cables, the polymer blend may
include large quantities of additives that change the
fire performance of the polymer completely. Knowing the
exact chemical compound is not necessary for an accurate
model, but the thermal degradation and the release of
combustible gases should be identified correctly.
The literature study of this dissertation summarises the
most important background information about pyrolysis
modelling and the thermal degradation of the polymers
needed for understanding the methods and results of this
dissertation. The articles cover developing methods for
pyrolysis modelling and testing them for various
materials. The sensitivity of the model for the modelling
choices is also addressed by testing several typical
modeller choices. The heat release of unknown polymer
blend is studied using Microscale Combustion Calorimetry
(MCC), and two methods are developed for effectively
using the MCC results in building an accurate reaction
path. The process of pyrolysis modelling is presented and
discussed. Lastly, the methods of cable modelling are
applied to a large scale simulation of a cable tunnel of
a Finnish nuclear power plant.
The results show that the developed methods are
practical, produce accurate fits for the experimental
results, and can be used with different materials. Using
these methods, the modeller is able to build an accurate
reaction path even if the material is partly
uncharacterised. The methods have already been applied to
simulating real scale fire scenarios, and the validation
work is continuing.
Original language | English |
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Qualification | Doctor Degree |
Awarding Institution |
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Supervisors/Advisors |
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Award date | 15 Nov 2013 |
Place of Publication | Espoo |
Publisher | |
Print ISBNs | 978-951-38-8101-6 |
Electronic ISBNs | 978-951-38-8102-3 |
Publication status | Published - 2013 |
MoE publication type | G5 Doctoral dissertation (article) |
Keywords
- pyrolysis modelling
- simulation
- polymer
- cables
- composites
- probabilistic
- risk assessment (PRA)