A refined methodology to determine the spatial and temporal variation in the emissivity of diffusion flames

Flame emissivity is an important parameter in the study of pool fires. A refined methodology is developed to determine the spatial and temporal variation in the flame emissivity of pool fires. Limitations of earlier methodologies include an assumption of axisymmetrical flame and the obtained data being spatially and temporally averaged. Experiments are performed with diesel and gasoline as the fuel for pool diameters of 0.3 m-1.0 m. Flame emissivity is obtained based on the calculation of flame transmissivity using an infrared camera with reference to electrically heated thin metal strips. Average emissivity is determined for the multi-averaged image of 80 instantaneous images. Complete spatial emissivity and temperature distribution are obtained. Vertical centerline emissivity matches reasonably well with the average emissivity reported in the literature.