Visible length and thermal radiation of WCO biodiesel and ethanol pool fires

Abstract

Pool fires are the most common form of fire scenarios which can occur with liquid biofuels. The detailed measurement of fire characteristics and safety distances from such fires are therefore essential for ensuring safety of people, infrastructure and environment. In the present work, characteristics such as Mass Burning Rate (MBR), fire length, fire temperature, Surface Emissive Power (SEP) and safety distance of two biofuels i.e. WCO (Waste Cooking Oil) biodiesel and ethanol pool fires are measured for five pool diameters (d = 0.05 m, 0.1 m, 0.2 m, 0.5 m and 1 m). In order to develop a range of uncertainties present data are compared with the earlier published data. The mass burning rate (depending on diameter) of both biofuels are measured to be 1.3–4.6 times smaller than gasoline because of the smaller heat flux back to the liquid pool which was confirmed from their lesser flame temperature. Due to the effect of cross-wind (3–4 m/s) at d = 1 m, smaller increase in burning rate was measured for ethanol than biodiesel which was otherwise higher for all other diameters where experiments were conducted in controlled environment. As a result shorter flames and small flame temperature are measured which led SEP of both biofuels to be comparable with each other and lie in the range of 10–20 kW/m2(d⩽1) m which is considerably less (1.8–3.7 times) than their equivalent gasoline fires. The measured thermal safety distances are also 2–3 times smaller than gasoline. Correlations are developed in terms of the pool diameters as per the standards prescribed by EN1473 and NFPA 49 CFR which can be utilized in land use planning for WCO biodiesel and ethanol storage tanks.