Examination of radiative fraction of small-scale pool fires at reduced pressure environments

Abstract

Determining flame radiative fraction is necessary in the estimation of radiation heat transfer of a fire, while the radiative fraction for a given fuel is usually regarded as constant, even at sub-atmospheric pressures. To ascertain the factors affecting this parameter, a series of small-scale n-heptane pool fires with diameters of 4–10 cm are performed at low pressures by means of an altitude chamber in this work. Based on a point source model, the radiative fractions of tested pool fires are determined, and coupled effects of pressure and pool diameter on this parameter are observed. A dimensional scaling theory is further proposed to interpret these effects, i.e. Xr~P0.3−0.175αD0.15, and the experimental results can be well correlated with this model. The findings will be helpful in evaluating the radiative heat fluxes of pool fires at reduced pressures more accurately, further providing guidance on the detection of incipient fires at sub-atmospheric pressure environments.