Fire Technology

, Volume 44, Issue 2, pp 167–184

An Overview of Design Fires for Building Compartments

Article

DOI: 10.1007/s10694-007-0031-7

Cite this article as:
Bwalya, A. Fire Technol (2008) 44: 167. doi:10.1007/s10694-007-0031-7

Abstract

The worldwide trend of moving towards performance-based codes has brought about a need for computational tools, most of which rely on suitably-defined design fires, to adequately predict the impact of fires on buildings and their occupants. This literature review was carried out to determine the range of methods used to characterize design fires. The methods currently available were found to be largely empirical in nature and unsophisticated. The two main quantities used to describe design fires are the heat release rate (pre-flashover scenario) and temperature-time profiles (post-flashover). The most commonly used pre-flashover design fires are t2 fires, whereas a host of empirical correlations are available for post-flashover design fires.

Keywords

design firesheat release ratet2 firepre-flashoverpost-flashover

Nomenclature

Af

Floor area (m2)

Ao

Area of a ventilation opening (m2)

At

Total internal area of bounding surfaces of an enclosure (m2)

b

A parameter in Equation (7), =\(\sqrt{k\rho c_{\rm p}}\) (W s0.5/m2K)

bref

Reference value of b (W s0.5/m2K)

c

Constant used in Equation (18)

cp

Specific heat capacity (kJ/kg K)

Ho

Height of ventilation opening (m)

Fo

Opening factor (m1/2)

Fref

Reference value of the opening factor (m1/2)

Fv

Ventilation factor (m5/2)

k

Thermal conductivity (kW/m K)

kp

Pyrolysis coefficient (kg/s m5/2)

\(M^{\prime\prime}_{\rm f}\)

Fire load density (kg/m2)

\(\dot{Q}\)

HRR (kW)

\(\dot{Q}_{\rm o}\)

Reference HRR (kW)

Q′′

Total fire load energy density (MJ/m2)

\({\dot{q}}^{\prime\prime}_{i}\)

Incident radiation heat flux (MW/m2)

R

Radial distance (m)

Rp

Rate of pyrolysis

T

Temperature (°C)

To

Reference temperature (°C)

t

Time (s)

tb

Duration of burning (s)

td

Duration of heating phase, given by Equation (11) (h)

to

Time to reach a reference HRR (s)

tmax

Time at which maximum temperature occurs (min)

t*

Fictitious time used in Equation (6) (h)

Greek Letters

α

Growth or decay constant for a t2 fire (W/s)

β

A constant given by Equation (14) (K s−1/6)

δ

Shape constant

ρ

Density (kg/m3)

Subscripts

f

Floor

g

Pertains to hot gas

max

Maximum value

Ambient condition

Abbreviations

HRR

Heat release rate (kW)

Max

Maximum

RHR

HRR (synonymous with HRR) (kW)

Copyright information

© Springer Science+Business Media, LLC 2007

Authors and Affiliations

  1. 1.National Research Council of Canada, Institute for Research in Construction—Fire Research ProgramOttawaCanada