Thermal radiation model for the buoyancy-controlled diffusion plumes from rectangular fire sources

Abstract

This study investigated the thermal radiation from a rectangular fire source with different aspect ratios. Fire experiments with burners of the same surface area but different aspect ratios were conducted. The flame was split into several sub-flames as the aspect ratio of burner increased. Compared with the axis-symmetric fire source, the flame split in the rectangular fire source led to a change in the thermal radiation mechanism. Thus, a multi-cuboid flame model was developed to estimate the radiant heat flux from a rectangular fire source. The number of sub-cuboid flames considered in the proposed model depended on the aspect ratio of the rectangular fire source. Compared with experimental results and data available in the literature, the standard error of estimation by the developed model was 0.505, indicating that the proposed model outperformed the cuboid flame and point source models found in the literature. This developed model has better prediction for the thermal radiation from rectangular fire source with large aspect ratio. Based on sensitivity analysis of model parameter, the ratio of the aspect ratio of the burner to the number of sub-cuboid flames could be considered as a constant. Thus, this proposed model can be applied to risk assessment of rectangular fire.