Measurement of geometric and radiative properties of heptane pool fires

Abstract

The objective of the present work is to characterize heptane pool fires for pool diameters ranging from 0.1 m to 1.0 m, in a quiescent environment. Characterization of pool fires is done by determining various parameters such as the mass burning rate, puffing frequency, flame height, optical thickness, spatial distribution of emissivity and temperature, irradiance and fire safety distance. Measurement of the instantaneous mass burning rate indicates the presence of two steady states: an initial steady state and a bulk boiling steady state. The mass burning rate is found to decrease with increase in the free board height. Flame height is determined based on the definition of intermittency. Puffing frequency is obtained from the visible images by tracking the vortical structures in flames. The obtained results for the flame height and puffing frequency match well with the correlations presented in the literature.Flame emissivity is determined from the mass burning rate as well as a refined technique that determines the transmissivity of the electrically heated strips placed behind the flame. Radiative properties such as temperature distribution and irradiance at a distance are calculated from the thermal images. The irradiance at a distance obtained using the infrared camera is compared with Schimdt-Boelter gauge. The effect of fire size on the optical thickness, radiative fraction and fire safety distance has been examined.