Unsteady burning of thin-layer pool fires

Abstract

The burning behavior of circular, thin-layer n-heptane pool fires having a diameter of 0.2 m and initial fuel thicknesses of 6.5 mm and 13 mm were experimentally studied. Fire parameters and temperature distribution in fuel were recorded during the experiments. Results show that flame height and burning rate exhibited different stages for fires with different thickness of fuel layer, while flame temperature was independent of the fuel layer and was almost constant. The fuel surface temperature increased to its boiling point, with the temperature of fuel below the surface starting to rise shortly after ignition. A boiling zone was formed that increased with time for the thicker fuel layer. A theoretical analysis based on a heat-transfer model is proposed to explain the differences in heat transfer between the liquid and environment during the different burning phases. Reasons for the increase of burning rate are introduced.