Yue Hu, Jian Chen, Zhigang Wang, Ki Yong Lee, Matthew F. Bundy, Anthony P. Hamins, Marco G. Fernandez
A series of experiments was conducted to investigate the pre-combustion and combustion properties of corn oil heated in pans from 10 cm to 26 cm diameter by a residential electric- coil element cooktop. For comparison, torch-ignited gasoline, heptane and corn oil experiments were also conducted in the same configuration except without the heating element energized. This second configuration represents common pool fires with heat feedback to the fuel coming only from the fire above the burning pool. Heating the oil on a typical electric cooktop leads to gradual release of an aerosol following by auto-ignition. Continued heating of the oil on the cooktop leads to enhanced vaporization of the oil and rapidly growing fires with relatively large peak heat release rates. The heated-burning corn oil can boil-over, a phenomenon in which the oil bulk density decreases until it flows over the pan sides. For a given pan volume and heating rate, the occurrence of boil-over depends on the initial fuel volume. A suite of measurements are reported including the time to auto-ignition, heat release rate, mass evaporation and burning rates, radiative emission to the surroundings, radiative fraction, combustion efficiency, flame height, soot and CO yields, and the specific extinction area. The heat release rate increased with initial fuel mass for the auto-ignited corn oil fires. In the 26 cm diameter pan, the peak flame height and heat release rate were 1.4 m and 110 kW, respectively. Fires of this size pose a significant hazard and can ignite nearby flammable materials including cellulosic cabinetry, which is often located above a residential cooktop.